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SDLRC - Plate Tectonics


The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Plate Tectonics
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Keyword Index
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Media/Corporate References by Name for all years
A B C D-Diam Diamonds Diamr+ E F G H I J K L M N O P Q R S T U V W X Y Z
Each article reference in the SDLRC is tagged with one or more key words assigned by Pat Sheahan to highlight the main topics of the article. In an effort to make it easier for users to track down articles related to a specific topic, KRO has extracted these key words and developed a list of major key words presented in this Key Word Index to which individual key words used in the article reference have been assigned. In most of the individual Key Word Reports the references are in crhonological order, though in some such as Deposits the order is first by key word and then chronological. Only articles classified as "technical" (mainly scientific journal articles) and "media" (independent media articles) are included in the Key Word Index. References that were added in the most recent monthly update are highlighted in yellow.

Plate Tectonics is the most important scientific theory to emerge in the field of geology which is apparent in the detailed Wikipedia discussion. The theory has its roots in the observation of Alfred Wegener in 1912 that the continents appear to fit together, leading to the notion of "continental drift". But what puzzled everybody was what mechanism drove the movements of this earthly jigsaw puzzle. The emergence of geophysical surveys after World War II helped illuminate the seafloor so that the lithosphere came to be understood as a mobile assembly of "plates". But geophysics also illuminated the earth's innards, which led to the theory of plate tectonics in the mid sixties, namely that the semi-solid mantle between the liquid outer core and the solid crust sustains convection cells which drive the lateral movement of the lithospheric plates, causing magmatic upwellings at seafloor spreading centers as well as within the subduction zones where denser oceanic plates slid under lighter continental crust, and orogenies where crustal plates collide with each other to drive mountain building uplift as well as metamorphism. Articles tagged as "plate tectonics" tend to be of a scientific nature and deal with the movement of plates and the mechanisms driving this movement. The topic is relevant to diamonds because diamonds are formed in the mantle, but it is the nature of the crust and the phenomenon of discrete magmatism which results in diamond being available for discovery at the earth's surface where pressure and temperature conditions are such that it is impossible for diamonds to form. Diamonds are relevant to plate tectonics because they are "messages in a bottle" from inside the earth whose commercial value enables scientific research into the nature and history of the earth.

Plate Tectonics
Posted/
Published
AuthorTitleSourceRegionKeywords
DS1910-0538
1917
Singleton, E.Precious GemsThe Mentor., SERIAL No. 124, Vol. 4, No. 24, FEBRUARY 12P.GlobalDiamonds Notable, Plates
DS1970-1001
1974
Vartianen, H., Woolley, A.R.The Age of the Sokli Carbonatite FIn land and Some Relationships of the North Atlantic Alkaline Igneous Province.Bulletin. COMM. GEOL. FINLANDE., Vol. 46, PP. 81-91.GlobalCarbonatite, Alnoite, Plate Tectonics
DS1975-0784
1978
Koljonen, T., Rosenberg, R.Rare Earth Elements in Carbonatites and Related Rocks As Indications of Their Plate Tectonic Origin.Unknown., GlobalRare Earth Elements (ree), Carbonatite, Plate Tectonics
DS1984-0475
1984
Malkov, B.A., Milanovskiy, Y.Y., Kropotkin, P.N., Pushcharovski.Archean Diamond Bearing Mantle and Kimberlite Volcanism in The Expanding Earth Theory.Izd. Nauka, Moscow., PP. 56061.RussiaIgneous Rocks, Kimberlite, Genesis, Plate Tectonics
DS1987-0526
1987
Nixon, P.H.Mantle xenolithsJohn Wiley, 850pGlobalState of the Art, Regional geology, Craton, plate, processe, Mantle magma, Metasomatism
DS1988-0438
1988
Manspeizer, W.Continental break up and origin of the Atlantic ocean and passivemarginsElsevier, Dev. in Geotectonics No. 22, 998p. $ 294.75 United StatesAfrica, North AmericaPlate tectonics, Outline of book
DS1989-0376
1989
Dunbar, J.A., Sawyer, D.S.How preexisting weaknesses control the style of continental breakupJournal of Geophysical Research, Vol. 94, No. B6, June 10, pp. 7278-7292GlobalTectonics, Plate tectonics
DS1989-1297
1989
Rogers, J.J.W., Rosendahl, B.R.Perceptions and issues in continental riftingJournal of African Earth Sciences, Vol. 8, No. 2/3-4, pp. 137-42.East Africa, TanzaniaTectonics - rifting, plate
DS1989-1301
1989
Rogers, R.D.Use of observational patterns in geologyGeology, Vol. 17, No. 2, February pp. 131-134GlobalDatabase interpretive, Plate tectonics
DS1989-1314
1989
Ruff, L.J., Kanamori, H.Introduction to subduction zonesPageophy., (Pure and Applied Geophysics), Vol. 129, No. 1-2, pp. 1-5. Database # 17555BasinSubduction zone, Plate tectonics
DS1989-1489
1989
TectonophysicsPaleozoic plate tectonics with emphasis on the European Caledonian and variscan beltsTectonophysics, Vol. 169, No. 4, pp. 221-350Europe, Finland, Norway, Scotland, ScandinaviaPlate tectonics, Caledonides, Tectonics
DS1990-0187
1990
Beloussov, V., Bevis, M.G., Crook, K.A.W., et al.Critical aspects of the plate tectonic theory- Vol. I. criticism on the plate tectonic theory. Vol. II Alternative theoriesAugustithis Publishing, (Greece), Vol. I. 435p. $ 50.00 Vol. II 444p. $ 50.00GlobalPlate tectonics, Theories
DS1990-0705
1990
Hoffman, P.F.Archaean continental plates: old and young mantle rootsNature, Vol. 347, No. 6288, September 6, p. 19GlobalMantle, Plates
DS1990-0966
1990
Macdonald, K.C., Fox, P.J.The mid-ocean ridgeOcean Resources NL., Trans Hex International Ltd., Vol. 262, No. 6, June pp. 72-95Ocean RidgeTectonics, Plate tectonics
DS1990-1052
1990
Minster, J-B.Plate tectonics: new plates, rates and datesNature, Vol. 346, No. 6281, July 19, p. 218GlobalPlate tectonics, Geochronology
DS1990-1068
1990
Morris, J.D., Leeman, W.P., Tera, F.The subducted component in island arc lavas: constraints from Berylium isotopes and Boron-Berylium systematicsNature, Vol. 344, No. 6261, March 1, pp. 31-36GlobalPlate tectonics, Island arcs -Beryllium /boron
DS1990-1308
1990
Scheibner, E.The tectonics of New South Wales in the second decade of application of the plate tectonics paradigM.Journal of Proceedings of the Royal Soc. New South Wales, Vol. 122, pp. 35-74AustraliaTectonics, Plate tectonics
DS1990-1373
1990
Sleep, N.H.A reprieve for ocean crustNature, Vol. 347, No. October 11, pp. 518-519GlobalOphiolite, Plate tectonics, mantle
DS1990-1408
1990
Srivastava, S.P., Schouten, H., Roest, W.R., et al.Iberian plate kinetics: a jumping plate boundary between Eurasia andAfricaNature, Vol. 344, No. 6268, April 19, pp. 756-759NewfoundlandPlate tectonics, Iberian plate
DS1990-1438
1990
Sychanthavong, S.P.H.Crustal evolution and orogenyA.a. Balkema, 339p. approx. $ 40.00Africa, CaliforniaTable of contents, Crustal evolution, plate tectonics
DS1990-1443
1990
Tao WeipingNon-metallic mineral deposits of Chin a and plate tectonicsChina Earth Sciences, Vol. 1, No. 2, pp. 110-122ChinaPlate tectonics, Non-diamonds
DS1990-1495
1990
Van Den Beukel, P.J.Thermal and mechanical modelling of convergent plate marginsGeol. Ultraiectina, University of Utrech, Institute of Earth Sciences, The, No. 62, 126pGlobalOphiolites, Plate Tectonics, Table of contents only
DS1990-1550
1990
Weijermars, R.New fit GondwanaJournal of African Earth Sciences, Vol. 11, No. 3/4, pp. 421-436GondwanaTectonics, plate tectonics, Structure
DS1990-1568
1990
Wilson, D.S.Kinematics of overlapping rift propagation with cyclic rift failureEarth and Planetary Science Letters, Vol. 96, pp. 384-392GlobalPlate tectonics, Rifting
DS1991-0027
1991
Apperson, K.D.Stress fields of the overriding plate at convergent margins and beneath active volcanic arcs.Science, Vol. 254, Nov. 1, pp. 670-8.GlobalTectonics, plate tectonics, seismic, Asthenosphere, subduction
DS1991-0108
1991
Besse, J., Corutillot, V.Revised and synthetic apparent polar wander paths of the African North American and Indian plates, and true polar wander path since 200MaJournal of Geophysical Research, Vol. 96, No. B3, March 10, pp. 4029-4050South Africa, United States, IndiaPaleomagnetism, Plate tectonics
DS1991-0155
1991
Bott, M.H.P.Sublithospheric loading and plate boundary forcesPhil. Transactions Royal Society of London, Vol. 337, No. 1645, October 15, pp. 83-94GlobalMantle, Plate tectonics
DS1991-0450
1991
EpisodesAntarctica and North America kinship postulatedEpisodes, Vol. 14, No. 2, June pp. 149-150GlobalPaleogeography, Plate tectonics
DS1991-0525
1991
Galer, S.J.G.Inter relationships between continental freeboard, tectonics and mantletemperatureEarth and Planetary Science Letters, Vol. 105, pp. 214-228GlobalSea-level, Archean tectonics
DS1991-0741
1991
Howell, B.F. Jr.How misconceptions on heat flow may have delayed discovery of platetectonicsEarth Sciences History, Vol. 10, No. 1, pp. 44-50GlobalHistory, Plate tectonics
DS1991-0814
1991
Jurdy, D.M., Stefanik, M.The forces driving the plates: constraints from kinematics and stressobservationsPhil. Transactions Royal Society of London, Vol. 337, No. 1645, October 15, pp. 127-140GlobalMantle, Plate tectonics
DS1991-1420
1991
Richardson, R.M., Reding, L.M.North American plate dynamics #1Journal of Geophysical Research, Vol. 96, No. B7, July 10, pp. 12, 201-12, 224North AmericaTectonics, Plate
DS1991-1421
1991
Richardson, R.M., Reding, L.M.North American plate dynamics #2Journal of Geophysical Research, Vol. Paper # 91JB00958United States, CanadaTectonics, Plates, Paper
DS1992-0188
1992
Burchfiel, B.C.The Cordilleran Orogen: conterminous U.SGeology of North America DNAG volume, No. G-3, 700pCordilleraBook -table of contents, Plate tectonics, paleogeography, orogen, metamorphism
DS1992-0322
1992
Daala Salda, L., Cingolani, C., Varela, R.Early Paleozoic orogenic belt of the Andes in southwestern South America:results of Laurentia-Gondwana collision?Geology, Vol. 20, No. 7, July pp. 617-620South AmericaTectonics, Plate tectonics
DS1992-0328
1992
Dalziel, I.W.D.Late Gondwanide tectonic rotations within GondwanalandTectonics, Vol. 11, No. 3, June pp. 603-607Plate tectonics
DS1992-0329
1992
Dalziel, I.W.D.Pre-Mesozoic plate tectonics: new geologic ideas await paleomagnetictestingEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 93PangeaPaleomagnetics, Plate tectonics
DS1992-0330
1992
Dalziel, I.W.D.On the origin of LaurentiaGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A115South AmericaPlate tectonics, Terranes
DS1992-0340
1992
Davies, G.F.On the emergence of plate tectonicsGeology, Vol. 20, No. 11, November pp. 963-966GlobalPlate tectonics, Oceanic lithosphere
DS1992-0368
1992
Dobretsov, N.L.Analysis of the geology of USSR in terms of plate tectonicsRussian Geology and Geophysics, Vol. 33, No. 6, pp. 125-RussiaTectonics, Plate tectonics
DS1992-0504
1992
Gaal, G.Global Proterozoic tectonic cycles and Early Proterozoic metallogeny #1South African Journal of Geology, Vol. 95, No. 3-4, pp. 80-87PangeaPlate tectonics, Metallogeny, Supercontinent
DS1992-0566
1992
Giggenbach, W.F.Isotopic shifts in waters from geothermal and volcanic systems along convergent plate boundaries and their originEarth and Planetary Science Letters, Vol. 113, No. 4, November pp. 495-510GlobalGeothermal systems, Plate tectonics
DS1992-0734
1992
Hudnut, K.W.Geodesy tracks plate motionNature, Vol. 355, No. 6362, Feb. 20th. pp. 681-682CaliforniaPlate tectonics, Geodesy
DS1992-1023
1992
McCaffrey, R.Oblique plate convergence, slip vectors, and forearc deformationJournal of Geophysical Research, Vol. 97, No. B6, June 10, pp. 8905-8916GlobalSubduction, Plate tectonics
DS1992-1138
1992
Oliver, J.The spots and stains of plate tectonicsEarth Science Reviews, Vol. 32, pp. 77-106MantlePlate tectonics, Mantle hotspots
DS1992-1229
1992
Precambrian Research, Special IssuePrecambrian metallogeny related to plate tectonicsPrecambrian Research, Special Issue, Vol. 58, 450pGlobalMetallogeny, Plate tectonics, areas of interest
DS1992-1518
1992
Tao, W.C., O'Connell, R.J.Ablative subduction: a two sided alternative to the conventional subductionmodelJournal of Geophysical Research, Vol. 97, No. B6, June 10, pp. 8877-8904GlobalSubduction, Plate tectonics
DS1993-0456
1993
Fowler, A.C.Boundary layer theory and subductionJournal of Geophysical Research, Vol. 98, No. B 12, December 10, pp. 21, 997- 22, 005.MantleMantle convection, Plate tectonics
DS1993-1335
1993
Royden, L.H.Evolution of retreating subduction boundaries formed during continentalcollisionTectonics, Vol. 12, No. 3, June pp. 629-638Africa, South AfricaTectonics, Plate tectonics, Orogeny
DS1993-1426
1993
Sengor, A.M., Natalin, B.A., Burtman, V.S.Evolution of the Altaid tectonic collage and Paleozoic crustal growth inEurasiaNature, Vol. 364, July 22, pp. 299-306AsiaAngaran Craton, Plate tectonics
DS1993-1581
1993
TectonophysicsGeodynamics of rifting Volume III: thematic discussionsTectonophysics, Vol. 215, No. 1-2, pp. 1-230pGlobalBook -table of contents, Plate tectonics, rifting, rift systems
DS1993-1743
1993
Windley, B.F.Uniformitarianism today: plate tectonics is the key to the pastJournal of the Geological Society of London, Vol. 150, pp. 7-19OntarioPlate tectonics, Craton, suture zones
DS1994-0051
1994
Anderson, D.L.Superplumes or supercontinents?Geology, Vol. 22, No. 1, January pp. 39-42MantleSupercontinents, Plate tectonics, Hot spots
DS1994-0997
1994
Lay, T.The fate of descending slabsAnnual Review of Earth and Planet. Sciences, Vol. 22, pp. 33-62.MantleSubduction, Tectonics, plates
DS1994-1523
1994
Sandiford, M., Coblenz, D.Plate scale potential energy distributions and the fragmentation of ageingplates.Earth Planetary Science Letters, Vol. 126, No. 1-3, August pp. 143-160.MantleTectonics, Plate tectonics
DS1994-1526
1994
Santa Rosa, A.N.C., Rosa, J.W.C.Group velocity of fundamental mode Rayleigh waves recorded Belem- dat a set for Nazca plate motions.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 142-144.BrazilGeophysics -Rayleigh, Plate tectonics
DS1994-1698
1994
Stock, J.M., Lee, J.Do microplates in subduction zones leave a geological record?Tectonics, Vol. 13, No. 6, Dec. pp. 1472-1487MantleSubduction, Plate tectonics
DS1995-0039
1995
Anderson, D.L.Lithosphere, asthenosphere and perisphereReviews of Geophysics, Vol. 33, No. 1, Feb. pp. 125-MantlePlate tectonics, Concepts -lithosphere, asthenosphere, perisphere
DS1995-0499
1995
EOSAnchor like force proposed for subduction zonesEos, Vol. 76, No. 49, Dec. 5, p. 497-8.MantleSubduction, Plate tectonics
DS1995-0655
1995
Gordon, R.G.Plate motions, crustal and lithospheric mobility and paleomagnetism:prospective viewpoint.Journal of Geophysical Research, Vol. 100, No. B12, Dec. 10, pp. 24, 367-392.Mantle, crustPlate boundaries, interiors, Paleomagnetism -review
DS1995-0734
1995
Hamilton, W.B.Subduction systems and magmatismvolcanism with extensions at plate Boundaries, Geological Society of London Special Paper 81, pp. 3-28.MantlePlate tectonics, Subduction
DS1995-1102
1995
Lithgow-Bertelloni, C., Richards, M.A.Cenozoic plate driving forcesGeophysical Research. Letters, Vol. 22, No. 11, June 1, pp. 1317-20.MantlePlate tectonics, Subduction, slabs
DS1995-1103
1995
Livelybrooks, D., Banks, R.J.Boundary between paleoplates investigated with several techniquesEos, Vol. 76, No. 31, August 1, pp. 305, 309.MantlePlates, Subduction
DS1995-1757
1995
Simkin, T., et al.The dynamic planet: world map of volcanoes, earthquakes, impact craters and plate tectonicsUnited States Geological Survey (USGS) Map, !: 30, 000, 000 $ 4.25GlobalMap, Volcanoes, craters, plate tectonics
DS1996-0156
1996
Borukaev, Ch.B.Late Archean plate tectonicsRussian Geology and Geophysics, Vol. 37, No. 1, pp. 29-36RussiaPlate tectonics, Archean
DS1996-0197
1996
Burke, K.The African plate. Alex du Toit Memorial LectureSouth African Journal of Geology, Vol. 99, No. 4, pp. 339-409AfricaReview - tectonics, TectonisM.
DS1996-0475
1996
Fryer, P.Evolution of Mariana convergent plate margin systemsReviews of Geophysics, Vol. 34, No. 1, Feb. pp 89-125GlobalPlate tectonics, Subduction
DS1996-0543
1996
Goodwin, A.M.Principles of Precambrian geologyAcademic Press, 400pGlobal, CanadaBook -ad, Precambrian geoloy, plate tectonics, geodynamics
DS1996-0613
1996
Hauri, E.Migration of magma from convecting magmaCarnegie Institute Yearbook 94, (1994-1995), pp. 116-128MantlePlate Tectonics, Mantle Plumes
DS1996-0660
1996
Idnurum, M.Prolonged Rodinian link bewteen North America and AustraliaGeological Society of Australia 13th. Convention held Feb., No. 41, abstracts p.211.AustraliaPlate tectonics, Gondwanaland, Rodinia
DS1996-0834
1996
Lennykh, V.I., Valizer, P.M., Beane, R., et al.Petrotectonic evolution of the Maksyutov Complex, southern Urals, Russia:implications for metamorphismInternational Geology Review, Vol. 37, pp. 584-600.Russia, UralsPlate tectonics, Metamorphism -ultra high pressure
DS1996-0843
1996
Li, Z.X.Role of the major east Asian cratonic blocks in the assembly and breakup of supercontinent Rodinia.Geological Society of Australia 13th. Convention held Feb., No. 41, abstracts p.249.AustraliaPlate tectonics, Gondwanaland, Rodinia
DS1996-1202
1996
Rogers, J.J.W.A history of the continents in the past three billion yearsJournal of Geology, Vol. 104, No. 1, pp. 91-108MantlePlate tectonics, Gondwanaland, Pangea
DS1996-1561
1996
Worku, H., Schandelmeier, H.Tectonic evolution of the Neoproterozoic Adola belt of southern Ethiopia:evidence for a Wilson Cycle processPrecambrian Research, Vol. 77, No. 3-4, April pp. 179-210GlobalTectonics, Plate collision, Adola Belt
DS1997-0135
1997
Brune, J.N., Ellis, M.A.Structural features in a brittle ductile wax model of continentalextensionNature, Vol. 387, May 1, pp. 67-69MantleStructure, plate tectonics, Rifting
DS1997-0166
1997
Carlowicz, M.Was Cambrian explosion the result of wandering continents?Eos, Vol. 78, No. 36, Sept. 9, pp. 381, 382MantlePlate tectonics, Cambrian Explosion
DS1997-0500
1997
Helmstaedt, H.H., Gurney, J.J.Geodynamic controls of kimberlites - what are the roles of hotspot and plate tectonics?Russian Geology and Geophysics, Vol. 38, No. 2, pp. 492-508.MantleHotspots, Plate tectonics
DS1997-0893
1997
Pavoni, N.Geotectonic bipolarity - evidence of bicellular convection in the Earth'smantleSouth African Journal of Geology, Vol. 100, 4, Dec. pp. 291-299MantlePlate tectonics, Lithosphere
DS1997-1016
1997
Segall, P., Davis, J.L.GPS applications for geodynamics and earthquake studiesAnnual Review of Earth and Planetary Sciences, Vol. 25, pp. 301-336GlobalGlobal Positioning System, geodesy, coseismic, Tectonics, plate boundaries, glacial isostatic
DS1997-1116
1997
Storey, B.C., Kyle, P.R.An active mantle mechanism for Gondwana breakupSouth African Journal of Geology, Vol. 100, 4, Dec. pp. 283-290GlobalPlate tectonics, Mantle plumes, megaplume
DS1997-1117
1997
Storey, B.C., Kyle, P.R.An active mantle mechanism for Gondwana breakupSouth African Journal of Geology, Vol. 100, 4, Dec. pp. 283-290.GlobalPlate tectonics, Mantle plumes, megaplume
DS1997-1303
1997
Zonenshain, L.P., Kuzmin, M.I., Page, B.M.Paleogeodynamics.. The plate tectonic evolution of the earthAmerican Geophysical Union (AGU) Geodynamic Series, Special Paper, 218p. approx. $ 45.00MantleLithosphere, Plates, boundaries, Hot spots, Paleomagnetism
DS1998-0021
1998
Allbarede, F.Reconciling mantle rare gas geochemistry with tomographic evidence of whole mantle convection.Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 34-5.MantleGeophysics - seismic, Plate tectonics
DS1998-0440
1998
Foster, D.A., Ehlers, K.40Ar 39Ar thermochronology of the southern Gawler Craton - implications for East Gondwana and Rondinia.Journal of Geophysical Research, Vol. 103, No. 5, May 10, pp. 10177-94.AustraliaMesoproterozoic, Neoproterozoic, Geochronology, Gondwana
DS1998-0880
1998
Lithgow-Bertelloni, C., Richards, M.A.The dynamics of Cenozoic and Mesozoic plate motionsReviews of Geophysics, Vol. 36, No. 1, Feb. pp. 27-78.GlobalSubduction zones, geodynamics, Plate tectonics
DS1998-1484
1998
Trompert, R., Hansen, U.Mantle convection simulations with rheologies that generate plate likebehaviour.Nature, Vol. 395, No. 6703, Oct. 15, pp. 686-688.MantleSubduction, Plate
DS1998-1576
1998
White, D., Helmstaedt, H., Harrap, R., Thurston, P.The origin of our continent: LITHOPROBE seismic investigations in The western Superior TransectThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 90, No. 1017, Feb. pp. 78-82OntarioLithoprobe, Plate tectonics
DS1998-1649
1998
Zonenshain, L.P., et al.Paleogeodynamics... the plate tectonic evolution of the earthAmerican Geophysical Union (AGU) Special Publication, 218p.p. $ 45.00MantleTable of contents, Plates, boundari8es, hot spots, paleomagnetics
DS1999-0225
1999
Frei, R., Blenkinsop, T.G., Schonberg, R.Geochronology of the late Archean Razi and Chilimanzi suites of granites in Zimbabwe - tectonicsSouth African Journal of Geology, Vol. 102, No. 1, Jan. pp. 55-64.ZimbabweCraton, Limpopo Belt, Archean tectonics
DS1999-0270
1999
Grover, J.C.Earth Universe Cosmos: an inquest into our creeds (book by S.Warren Carey)Journal of Proceedings of the Royal Society. New South Wales., Vol. 132, pp. 118-22.GlobalBook review, Uniformitarianism, plate tectonics, BIF.
DS2000-0200
2000
Dalziel, I.W.D., Lawver, L.A., Murphy, J.B.Plumes, orogenesis, and supercontinental fragmentationEarth and Planetary Science Letters, Vol. 178, No. 1-2, May 15, pp. 1-12.MantleMantle plumes, Genesis - Tectonics, plate
DS2000-0810
2000
Regenauer-Lieb, K., Yuen, D.A.Fast mechanisms for the formation of new plate boundariesTectonophysics, Vol.322, No.1-2, July10, pp.53-68.MantleTectonics, Plates
DS2001-0542
2001
Jolivet, L., Nataf, H.C.Geodynamics and rheology of the lithosphere along the DSS profile SVEKA in the central Scandinavian Shield.Balkema Publishing, 236p. approx. $ 90.00GlobalBook - ad, Tectonics, plate boundaries
DS2001-0546
2001
Jones, A.G., Ferguson, I.J., Chave, Evans, McNeiceElectric lithosphere of the Slave CratonGeology, Vol. 29, No. 5, May, pp. 423-6.Northwest TerritoriesGeophysics - magnetotelluric, electromagnetic, Plate tectonics, kimberlite pipes
DS2001-0582
2001
Keith, M.Evidence for a plate tectonic debateEarth Science Reviews, Vol. 55, No. 4, pp. 235-336.MantlePlate tectonics, Review
DS2002-0037
2002
Anderson, D.L.How many plates?Geology, Vol.30,5,May,pp. 411-4., Vol.30,5,May,pp. 411-4.GlobalTectonics, geodynamics, plates, list, area, Pattern, statistics
DS2002-0038
2002
Anderson, D.L.How many plates?Geology, Vol.30,5,May,pp. 411-4., Vol.30,5,May,pp. 411-4.GlobalTectonics, geodynamics, plates, list, area, Pattern, statistics
DS2002-0840
2002
Khain, V.E., Ryabukhin, A.G.Russian geology and the plate tectonics revolution. p. 192 mentions kimberlite brieflyGeological Society of London, Special Publication, 192, pp. 185-198.RussiaPlate tectonics - history
DS2002-0925
2002
Le Grand, H.E.Plate tectonics, terranes and continental geologyGeological Society of London, Special Publication, 192, pp. 199-214.GlobalPlate tectonics - history
DS2002-1162
2002
Nutman, A.P., Friend, C.R.L., Bennett, V.C.Evidence for 3650-3600 Ma assembly of the northern end of the Itsaq Gneiss Complex: implication for...Tectonics, Vol.21,1,Feb.pp.4-1,4-17.GreenlandArchean tectonics, Geochronology
DS2002-1191
2002
Oreskes, N.Plate tectonics: an insider's history of the modern theory of the EarthWestview Press, 496p. $ 35.00GlobalBook, Plate tectonics
DS2002-1332
2002
Ribeiro, A.Soft plate and impact tectonicsSpringer, www.springer-ny.com/newspreviews, 260p.$70.GlobalBook - ad, Plate tectonics
DS2002-1333
2002
Ribeiro, A.Soft plate and impact tectonicsSpringer-ny.com, 260p.approx.$70.GlobalBook - ad, Plate tectonics, global, Wilson Cycle, geodynamics
DS2002-1564
2002
Stuwe, K.Introduction to the geodynamics of the lithosphere: quantitative description of geological problems.Springer, 450p.GlobalBook - geodynamics, model, plate tectonics, mathematica
DS2003-1245
2003
Sears, J.W., Price, R.A.Tightening the Siberian connection to western LaurentiaGeological Society of America Bulletin, Vol. 115, 8, August pp. 943-53.Russia, Australia, CanadaCordillera, Rodinia, plate reconstruction, Proterozoic
DS200412-0045
2004
Appleyard, C.M., Viljoen, K.S., Dobbe, R.A study of eclogitic diamonds and their inclusions from the Finsch kimberlite pipe, South Africa.Lithos, Vol. 77, 1-4, Sept. pp. 317-332.Africa, South AfricaProterozoic, dodecahedra, deformation, type IaAB, plate
DS200412-0996
2002
Khain, V.E., Ryabukhin, A.G.Russian geology and the plate tectonics revolution. p. 192 mentions kimberlite briefly.Geological Society of London, Special Publication, 192, pp. 185-198.RussiaPlate tectonics - history
DS200412-1091
2002
Le Grand, H.E.Plate tectonics, terranes and continental geology.Geological Society of London, Special Publication, 192, pp. 199-214.GlobalPlate tectonics - history
DS200412-1358
2004
Moore, J.M., Moore, A.E.The roles of primary kimberlitic and secondary Dwyka glacial sources in the development of alluvial and marine diamond depositsJournal of African Earth Sciences, Vol. 38, 1-2, Jan. pp. 115-134.Africa, South AfricaPaleo drainage, alluvials, Koa River, Bushmanland Plate
DS200412-1780
2003
Sears, J.W., Price, R.A.Tightening the Siberian connection to western Laurentia.Geological Society of America Bulletin, Vol. 115, 8, August pp. 943-53.Russia, Australia, CanadaCordillera, Rodinia, plate reconstruction, Proterozoic
DS200412-1946
2002
Stuwe, K.Introduction to the geodynamics of the lithosphere: quantitative description of geological problems.Springer, 450p.GlobalBook - geodynamics, model, plate tectonics, mathematica
DS200412-2232
2004
Ziegler, P.A., Cloetingh, S.Dynamic processes controlling evolution of rifted basins.Earth Science Reviews, Vol. 64, pp. 1-50.GlobalMagmatism, Tectonics, plate, rheology, geothermometry
DS200512-0182
2005
Condie, K.C.TTGs and adakites: are they both slab melts?Lithos, Vol. 80, 1-4, March pp. 33-44.MantleArchean tectonics, arc systems, mantle plume events
DS200512-0198
2005
Cruciani, C., Carminati, E., Doglioni, C.Slab dip vs lithosphere age: no direct function.Earth and Planetary Science Letters, In press,Mantle, South AmericaSubduction zones, geochronology, plate tectonics
DS200512-0299
2005
Foulger, G.R., Natland, J.H., Anderson, D.L.A source for Icelandic magmas in remelted Iapetus crust.Journal of Volcanology and Geothermal Research, Vol. 141, 1-2, March 1, pp.23-44.Europe, IcelandRecycled, subduction, tectonics, plates, gechemistry
DS200512-0358
2005
Govers, R., Wortel, M.J.R.Lithosphere tearing at STEP faults: response to edges of subduction zones.Earth and Planetary Science Letters, Vol. 236, pp. 505-523.Pacific IslandsGeodynamics, plate tectonics - not specific to diamonds
DS200512-0457
2005
Hyndman, R.D.Subduction zone backarcs, mobile belts and orogenic heat.GSA Today, Vol. 15, 2, pp. 4-10.MantleContinental tectonics
DS200512-1004
2005
Sleep, N.H.Evolution of the continental lithosphere.Annual Review of Earth and Planetary Sciences, Vol. 33, May pp. 369-393.MantleReview - tectonics
DS200612-0032
2006
Arcay, D., Doin, M-P., Tric, E., Bousquet, R.D.Overriding plate thinning in subduction zones: localized convection induced by slab dehydration.Geochemistry, Geophysics, Geosystems: G3, Vol. 7, Q02007MantleGeothermometry, hydrated slab-derived water fluxes
DS200612-0292
2006
Crowley, P.Charting Earth's activities: MAP - review of Simkin et al. This dynamic planet USGS I Map I-2800.Science, Vol. 313. p. 1241.Plate boundaries
DS200612-0408
2006
Fouch, M.J., Rondenay, S.Seismic anisotropy beneath stable continental interiors.Physics of the Earth and Planetary Interiors, In press - availableMantleGeophysics - seismics, plate tectonics
DS200612-0472
2006
Glukhovsky, M.Z.Giant swarms of Precambrian mafic dikes and potential diamond resources of ancient platforms.Geotectonics, Vol. 40, 1, Jan. pp. 11-24.Russia, CanadaDike swarms - mantle plumes, UHP, plate tectonics
DS200612-1088
2005
Pik, R., Marty, B., Hilton, D.R.How many mantle plumes in Africa? The geochemical point of view.Chemical Geology, Vol. 226, 3-4, pp. 100-114.AfricaAfrican plate, Hoggar, Tibesti, Darfur, Ethiopia, Kenya
DS200612-1114
2006
Pysklywee, R.N.Surface erosion control on the evolution of the deep lithosphere.Geology, Vol.34, 4, April pp. 225-228.MantlePlate collision, subduction, modeling
DS200612-1455
2006
Usui, T., Kobayashi, K., Nakamura, E., Helmstaedt, H.Trace element fractionation in deep subduction zones inferred from a lawsonite eclogite xenolith from the Colorado Plateau.Chemical Geology, in press available,United States, Colorado PlateauEclogite, subduction, Farallon plate, coesite
DS200612-1560
2006
Xu, Z., Wang, Q., Ji, S., Chen, J., Zeng, Yang, Chen, Liang, WenkPetrofabrics and seismic properties of garnet peridotite from the UHP Sulu terrane: implications for olivine deformation mechanism in subducting slab.Tectonophysics, Vol. 421, 1-2, pp. 111-127.MantleSubduction - cold, dry continental slab
DS200812-0024
2008
Alvey, A., Gaina, C.,Kusznir, N.J., Torsvik, T.H.Integrated crustal thickness mapping and plate reconstructions for the high Arctic.Earth and Planetary Science Letters, In press availableCanada, Arctic, GreenlandTectonics, plate, lithosphere
DS200812-0149
2008
Brun, J-P., Facccena, C.Exhumation of high pressure rocks driven by slab rollback.Earth and Planetary Science Letters, Vol. 272, 1-2, July 30, pp. 1-7.MantleHP - slab
DS200812-1004
2007
Santosh, M., Omari, S.CO2 flushing: a plate tectonic perspective.Gondwana Research, Vol. 13, 1, pp. 45-85.MantlePlate Tectonics
DS200812-1014
2008
Schellart, W.P., Stegman, D.R., Freeman, J.Global trench migration velocities and slab migration induced upper mantle volume fluxes: constraints to find an Earth reference frame based on minimizing viscous dissipation.Earth Science Reviews, Vol. 88, 1-2, May pp. 118-144.MantlePlate tectonics - subduction, convection, hotspot
DS200812-1059
2008
Shirey, S.B., Kamber, B.S., Whitehouse, M.J., Mueller, P.A., Basu, A.R.A review of isoptopic and trace element evidence for mantle and crustal processes in the Hadean and Archean: implications for the onset of plate tectonic subductionGeological Society of America Special Paper, 440, pp. 1-30.MantlePlate Tectonics
DS200912-0069
2008
Bradley, D.C.Passive margins through Earth history. CratonsEarth Science Reviews, Vol. 91, 1-4, Dec. pp. 1-26.Mantle, RussiaTectonics, plate velocity, collision, supercontinents
DS201112-0434
2011
Hirschmann, M.M.Deep Earth volatile cycles: from ancient to modern.Goldschmidt Conference 2011, abstract p.1028.MantleReservoirs of H and C, plate tectonics
DS201112-0952
2011
Shirey, S.B., Richardson, S.H.Start of the Wilson Cycle at 3 Ga shown by diamonds from subcontinental mantle.Science, Vol. 333, July 21, pp. 434-436.MantleSubduction, plate tectonics, mineral inclusions
DS201212-0173
2012
Duretz, T., Gerya, T.V., Kaus, B.J.P., Andersen, T.B.Thermomechanical modeling of slab eduction.Journal of Geophysical Research, Vol. 117, B08411 17p.MantlePlate tectonics - subduction
DS201212-0508
2012
Nair, R.R., Singh, Y., Trivedi, D., Kandpal, S.Ch.Anisotropy in the flexural response of the Indian shield.Tectonophysics, Vol. 532-535, pp. 193-204.IndiaPlate thickness
DS201212-0705
2012
Stixrude, L., Lithgow-Bertelloni, C.Geophysics of chemical heterogeneity in the mantle.Annual Review of Earth and Planetary Sciences, Vol. 40, pp. 569-595.MantlePlate tectonics, transition zone
DS201212-0747
2012
Van Hunen, J., Moyen, J-F.Archean subduction: fact or fiction?Annual Review of Earth and Planetary Sciences, Vol. 40, pp. 195-219.MantlePlate tectonics, geodynamics
DS201212-0781
2012
Williams, S.E., Muller, R.D., Landgrade, T.C.W., Whittaker, J.M.An open source software environment for visualizing and refining plate tectonic reconstructions using high resolution geological and geophysical dat a sets.Geology Today, Vol. 22, no. 4/5, pp. -9.TechnologyGplates
DS201312-0066
2013
Bedard, J.H.How many arcs can dance on the head of a plume? A comment on: a critical assessment of Neoarchean 'plume only' geodynamics: evdience from the Superior province, by D. Wyman and his reply as well.Precambrian Research, Vol. 229, pp. 189-202.MantlePlate Tectonics
DS201312-0468
2013
Kerr, R.A.The deep Earth machine is coming together.Science, Vol. 340, 6128, April 5, pp. 22-24.MantlePlate Tectonics
DS201412-0107
2014
Cawood, P.Studies show movements of continents speeding up after slow 'middle age'. Condie agrees - both presented at Gold schmidt 2014.eurekalert.org/pub, June 13, abstractsGondwana, RodiniaPlate Tectonics
DS201412-0108
2014
Cawood, P., Hawkesworth, C.J., Dhuime, B.The orgin of the continental crust and its impact on the Earth system.Goldschmidt Conference 2014, abstractGondwana, RodiniaPlate Tectonics
DS201412-0141
2014
Condie, K.C., Pisarevsky, S.A., Korenaga, J.Is there a secular change in supercontinent assemblies?Goldschmidt Conference 2014, abstractGondwanaPlate Tectonics
DS201412-0226
2014
Evans, R.Making the earth move.Nature, Vol. 509, pp. 40-41.MantlePlate Tectonics
DS201412-0462
2014
Kirby, J.F.Estimation of the effective elastic thickness of the lithosphere using inverse spectral methods: the state of the art.Tectonophysics, Vol. 631, pp. 87-116.MantlePlate tectonics, gravity
DS201505-0239
2015
Zahirovic, S., Muller, R.D., Seton, M., Flament, N.Tectonic speed limits from plate kinematic reconstructions.Earth and Planetary Science Letters, Vol. 418, pp. 40-52.GlobalPlate Tectonics
DS201508-0363
2015
Lee, C-T.A., McKenzie, N.R.Geochemistry: rise of the continents.Nature Geoscience, Vol. 8, pp. 506-507.MantlePlate Tectonics
DS201509-0390
2015
Cooper, C.M.Puzzling the pieces - supercontinent at depth.Geology, Vol. 43, 9, pp. 847-848.GlobalPlate reconstructions

Abstract: Alfred Wegener famously argued that the seemingly puzzle piece–like fit of the Atlantic coastlines was not a mere coincidence, but rather one line of evidence proving that the continents were once arranged as a single, coherent supercontinent (Wegener, 1912,1920). This puzzle piece observation eventually launched a revolution that changed our understanding of the Earth from its deep interior to evolutionary processes. Often, however, we think of the supercontinent puzzle in a two-dimensional sense, neglecting to include or consider how variations of the thickness of the puzzle pieces might also be at play. How do the puzzle pieces fit together at depth, and is there more to learn by including lithospheric thickness in our plate reconstructions? Would thinking three-dimensionally in our plate reconstructions help resolve some of the outstanding questions about supercontinents, continental deformation, and the lithosphere in general? This is the motivation of new research by McKenzie et al. (2015, p. 783 in this issue of Geology).
DS201601-0039
2015
Puchtel, I.S.When was the Earth's conveyor belt set in motion?American Mineralogist, Vol. 100, pp. 2369-2370.MantlePlate Tectonics

Abstract: The start of plate tectonics on Earth is one of the most controversial issues in modern geology, with proposed timings covering almost the entire history of our planet. On page 2387 of this issue (vol. 100, 2015), Blichert-Toft and co-authors report Sm-Nd and Lu-Hf isotopic and lithophile trace element data for early Archean komatiites from the Barberton Greenstone Belt (GB) in South Africa, and argue for the onset of plate tectonics on Earth as early as 3.5 Ga. The studied komatiites show a large decoupling of the two isotopic systems and lithophile trace element signatures that are most consistent with deep-water, pelagic sediments being present in the lower-mantle source of these lavas. Their conclusions have far-reaching implications for advancing our understanding of how the Earth system operated in the distant geological past.
DS201602-0235
2015
Schiffer, C., Stephenson, R.A., Petersen, K.D., Nielsen, S.B., Jacobsen, B.H., Balling, N., Macdonald, D.I.M.A sub crustal piercing point for North Atlantic reconstructions and tectonic implications.Geology, Vol. 43, 12, pp. 1087-1090.Europe, GreenlandPlate Tectonics

Abstract: Plate tectonic reconstructions are usually constrained by the correlation of lineaments of surface geology and crustal structures. This procedure is, however, largely dependent on and complicated by assumptions on crustal structure and thinning and the identification of the continent-ocean transition. We identify two geophysically and geometrically similar upper mantle structures in the North Atlantic and suggest that these represent remnants of the same Caledonian collision event. The identification of this structural lineament provides a sub-crustal piercing point and hence a novel opportunity to tie plate tectonic reconstructions. Further, this structure coincides with the location of some major tectonic events of the North Atlantic post-orogenic evolution such as the occurrence of the Iceland Melt Anomaly and the separation of the Jan Mayen microcontinent. We suggest that this inherited orogenic structure played a major role in the control of North Atlantic tectonic processes.
DS201609-1717
2016
Fischer, R., Gerya, T.Regimes of subduction and lithospheric dynamics in the Precambrian: 3D thermomechanical modelling.Gondwana Research, Vol. 37, pp. 53-70.MantlePlate Tectonics

Abstract: Comparing the early Earth to the present day, geological-geochemical evidence points towards higher mantle potential temperature and a different type of tectonics. In order to investigate possible changes in Precambrian tectonic styles, we conduct 3D high-resolution petrological-thermomechanical numerical modelling experiments for oceanic plate subduction under an active continental margin at a wide range of mantle potential temperature TP (? TP = 0 ? 250 K, compared to present day conditions). At present day mantle temperatures (? TP = 0 K), results of numerical experiments correspond to modern-style subduction, whereas at higher temperature conditions important systematic changes in the styles of both lithospheric deformation and mantle convection occur. For ? TP = 50 ? 100 K a regime of dripping subduction emerges which is still very similar to present day subduction but is characterised by frequent dripping from the slab tip and a loss of coherence of the slab, which suggests a close relationship between dripping subduction and episodic subduction. At further increasing ? TP = 150 ? 200 K dripping subduction is observed together with unstable dripping lithosphere, which corresponds to a transitional regime. For ? TP = 250 K, presumably equivalent to early Archean, the dominating tectonic style is characterised by small-scale mantle convection, unstable dripping lithosphere, thick basaltic crust and small plates. Even though the initial setup is still defined by present day subduction, this final regime shows many characteristics of plume-lid tectonics. Transition between the two end-members, plume-lid tectonics and plate tectonics, happens gradually and at intermediate temperatures elements of both tectonic regimes are present. We conclude, therefore, that most likely no abrupt geodynamic regime transition point can be specified in the Earth's history and its global geodynamic regime gradually evolved over time from plume-lid tectonics into modern style plate tectonics.
DS201701-0007
2017
Cooper, C.M., Miller, M.S., Moresi, L.The structural evolution of the deep continental lithosphere.Tectonophysics, Vol. 695, pp. 100-121.GlobalCraton, plate tectonics

Abstract: Continental lithosphere houses the oldest and thickest regions of the Earth's surface. Locked within this deep and ancient rock record lies invaluable information about the dynamics that has shaped and continue to shape the planet. Much of that history has been dominated by the forces of plate tectonics which has repeatedly assembled super continents together and torn them apart - the Wilson Cycle. While the younger regions of continental lithosphere have been subject to deformation driven by plate tectonics, it is less clear whether the ancient, stable cores formed and evolved from similar processes. New insight into continental formation and evolution has come from remarkable views of deeper lithospheric structure using enhanced seismic imaging techniques and the increase in large volumes of broadband data. Some of the most compelling observations are that the continental lithosphere has a broad range in thicknesses (< 100 to > 300 km), has complex internal structure, and that the thickest portion appears to be riddled with seismic discontinuities at depths between ~ 80 and ~ 130 km. These internal structural features have been interpreted as remnants of lithospheric formation during Earth's early history. If they are remnants, then we can attempt to investigate the structure present in the deep lithosphere to piece together information about early Earth dynamics much as is done closer to the surface. This would help delineate between the differing models describing the dynamics of craton formation, particularly whether they formed in the era of modern plate tectonics, a transitional mobile-lid tectonic regime, or are the last fragments of an early, stagnant-lid planet. Our review paper (re)introduces readers to the conceptual definitions of the lithosphere and the complex nature of the upper boundary layer, then moves on to discuss techniques and recent seismological observations of the continental lithosphere. We then review geodynamic models and hypotheses for the formation of the continental lithosphere through time and implications for the formation and preservation of deep structure. These are contrasted with the dynamical picture of modern day continental growth during lateral accretion of juvenile crust with reference to examples from the Australian Tasmanides and the Alaskan accretionary margin.
DS201707-1341
2017
Kornprobst, J.The forgotten fit of the circum-Atlantic continents.Comptes Rendus Geoscience, Vol. 349, pp. 42-48.Technologyplate tectonics

Abstract: Boris Choubert was a strong supporter of Wegener's continental drift theory. In 1935, he published a very accurate fit of the circum-Atlantic continents, which was based on continental edges instead of coastlines; in the same paper, he interpreted the Palaeozoic belts as the result of horizontal movements of the Precambrian blocks; so, he greatly expanded the role of continental drift through time. This original and very prophetic work was almost completely ignored by his contemporaries. Thirty years later (1965), Bullard, Everett and Smith published in turn a similar but more sophisticated fit; they did not acknowledge Choubert's initial work. Bullard's fit was met with immediate and tremendous success. The present paper analyses the reasons why Boris Choubert was frustrated of his pioneering role. This lack of recognition is related to: (1) a great evolution in the geological concepts between 1935 and 1965, and (2) a poor choice of Choubert, regarding the title of his 1935 article.
DS201707-1382
2017
Warren, C.When ancient continents collide.Nature Geoscience, Vol. 10, 4, pp. 245-246.Mantleplate tectonics

Abstract: The geological record preserves scant evidence for early plate tectonics. Analysis of eclogites - metamorphic rocks formed in subduction zones - in the Trans-Hudson mountain belt suggests modern-style subduction may have operated 1,800 million years ago.
DS201709-2032
2017
Meredith, A.S., Collins, A.S., Williams, S.E., Pisarevsky, S., Foden, J.D., Archibald, D.B., Blades, M.L., Alessio, B.L., Armistead, S., Plavsa, D., Clark, C., Muller, R.D.A full plate global reconstruction of the Neoproterozoic.Gondwana Research, Vol. 50, pp. 84-134.Globalneoproterozoic

Abstract: Neoproterozoic tectonic geography was dominated by the formation of the supercontinent Rodinia, its break-up and the subsequent amalgamation of Gondwana. The Neoproterozoic was a tumultuous time of Earth history, with large climatic variations, the emergence of complex life and a series of continent-building orogenies of a scale not repeated until the Cenozoic. Here we synthesise available geological and palaeomagnetic data and build the first full-plate, topological model of the Neoproterozoic that maps the evolution of the tectonic plate configurations during this time. Topological models trace evolving plate boundaries and facilitate the evaluation of “plate tectonic rules” such as subduction zone migration through time when building plate models. There is a rich history of subduction zone proxies preserved in the Neoproterozoic geological record, providing good evidence for the existence of continent-margin and intra-oceanic subduction zones through time. These are preserved either as volcanic arc protoliths accreted in continent-continent, or continent-arc collisions, or as the detritus of these volcanic arcs preserved in successor basins. Despite this, we find that the model presented here still predicts less subduction (ca. 90%) than on the modern earth, suggesting that we have produced a conservative model and are likely underestimating the amount of subduction, either due to a simplification of tectonically complex areas, or because of the absence of preservation in the geological record (e.g. ocean-ocean convergence). Furthermore, the reconstruction of plate boundary geometries provides constraints for global-scale earth system parameters, such as the role of volcanism or ridge production on the planet's icehouse climatic excursion during the Cryogenian. Besides modelling plate boundaries, our model presents some notable departures from previous Rodinia models. We omit India and South China from Rodinia completely, due to long-lived subduction preserved on margins of India and conflicting palaeomagnetic data for the Cryogenian, such that these two cratons act as ‘lonely wanderers’ for much of the Neoproterozoic. We also introduce a Tonian-Cryogenian aged rotation of the Congo-São Francisco Craton relative to Rodinia to better fit palaeomagnetic data and account for thick passive margin sediments along its southern margin during the Tonian. The GPlates files of the model are released to the public and it is our expectation that this model can act as a foundation for future model refinements, the testing of alternative models, as well as providing constraints for both geodynamic and palaeoclimate models.
DS201710-2229
2017
Greber, N.Plate tectonics started at least 3.5 billion years ago.Science News, Sept. 21, 1p.Mantletitanium, Plate Tectonics

Abstract: Plate tectonics may have gotten a pretty early start in Earth’s history. Most estimates put the onset of when the large plates that make up the planet’s outer crust began shifting at around 3 billion years ago. But a new study in the Sept. 22 Science that analyzes titanium in continental rocks asserts that plate tectonics began 500 million years earlier. Nicolas Greber, now at the University of Geneva, and colleagues suggest that previous studies got it wrong because researchers relied on chemical analyses of silicon dioxide in shales, sedimentary rocks that bear the detritus of a variety of continental rocks. These rocks’ silicon dioxide composition can give researchers an idea of when continental rocks began to diverge in makeup from oceanic rocks as a result of plate tectonics.But weathering can wreak havoc on the chemical makeup of shales. To get around that problem, Greber’s team turned to a new tool: the ratios of two titanium isotopes, forms of the same element that have different masses. The proportion of titanium isotopes in the rocks is a useful stand-in for the difference in silicon dioxide concentration between continental and oceanic rocks, and isn’t so easily altered by weathering. Those data helped the team estimate that continental rocks — and therefore plate tectonics — were already going strong by 3.5 billion years ago.
DS201710-2243
2017
Magni, V.Plate tectonics: crustal recycling evolution.Nature Geoscience, Vol. 10, 9, pp. 623-624.Mantleslab break-off

Abstract: The processes that form and recycle continental crust have changed through time. Numerical models reveal an evolution from extensive recycling on early Earth as the lower crust peeled away, to limited recycling via slab break-off today.
DS201801-0009
2017
Coltice, N., Larrouturou, G., Debayle, E., Garnero, E.J.Interactions of scales of convection in the Earth's mantle.Tectonophysics, in press available, 9p.Mantleplate tectonics, geophysics - seismics

Abstract: The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
DS201801-0057
2017
Scotese, C.Plate tectonics during last 1.5 billion years: an atlas of ancient oceans and continents.academia.edu blog, #35369866 101p. PdfGlobalplate tectonics - map
DS201802-0221
2018
Bedard, J.Stagnant lids and mantle overturns: implications for Archean tectonics, magmagenesis, crust growth, mantle evolution, and the start of plate tectonics.Geoscience Frontiers, Vol. 9, 1, pp. 19-49.Mantleplate tectonics

Abstract: The lower plate is the dominant agent in modern convergent margins characterized by active subduction, as negatively buoyant oceanic lithosphere sinks into the asthenosphere under its own weight. This is a strong plate-driving force because the slab-pull force is transmitted through the stiff sub-oceanic lithospheric mantle. As geological and geochemical data seem inconsistent with the existence of modern-style ridges and arcs in the Archaean, a periodically-destabilized stagnant-lid crust system is proposed instead. Stagnant-lid intervals may correspond to periods of layered mantle convection where efficient cooling was restricted to the upper mantle, perturbing Earth's heat generation/loss balance, eventually triggering mantle overturns. Archaean basalts were derived from fertile mantle in overturn upwelling zones (OUZOs), which were larger and longer-lived than post-Archaean plumes. Early cratons/continents probably formed above OUZOs as large volumes of basalt and komatiite were delivered for protracted periods, allowing basal crustal cannibalism, garnetiferous crustal restite delamination, and coupled development of continental crust and sub-continental lithospheric mantle. Periodic mixing and rehomogenization during overturns retarded development of isotopically depleted MORB (mid-ocean ridge basalt) mantle. Only after the start of true subduction did sequestration of subducted slabs at the core-mantle boundary lead to the development of the depleted MORB mantle source. During Archaean mantle overturns, pre-existing continents located above OUZOs would be strongly reworked; whereas OUZO-distal continents would drift in response to mantle currents. The leading edge of drifting Archaean continents would be convergent margins characterized by terrane accretion, imbrication, subcretion and anatexis of unsubductable oceanic lithosphere. As Earth cooled and the background oceanic lithosphere became denser and stiffer, there would be an increasing probability that oceanic crustal segments could founder in an organized way, producing a gradual evolution of pre-subduction convergent margins into modern-style active subduction systems around 2.5 Ga. Plate tectonics today is constituted of: (1) a continental drift system that started in the Early Archaean, driven by deep mantle currents pressing against the Archaean-age sub-continental lithospheric mantle keels that underlie Archaean cratons; (2) a subduction-driven system that started near the end of the Archaean.
DS201802-0227
2018
Condie, K.C.A planet in transition: the onset of plate tectonics on Earth between 3 and 2 Ga?Geoscience Frontiers, Vol. 9, 1, pp. 51-60.Mantleplate tectonics

Abstract: Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga. Among the more important of these are the following: (1) increasing proportion of basalts with “arc-like” mantle sources; (2) an increasing abundance of basalts derived from enriched (EM) and depleted (DM) mantle sources; (3) onset of a Great Thermal Divergence in the mantle; (4) a decrease in degree of melting of the mantle; (5) beginning of large lateral plate motions; (6) appearance of eclogite inclusions in diamonds; (7) appearance and rapid increase in frequency of collisional orogens; (8) rapid increase in the production rate of continental crust as recorded by zircon age peaks; (9) appearance of ophiolites in the geologic record, and (10) appearance of global LIP (large igneous province) events some of which correlate with global zircon age peaks. All of these changes may be tied directly or indirectly to cooling of Earth's mantle and corresponding changes in convective style and the strength of the lithosphere, and they may record the gradual onset and propagation of plate tectonics around the planet. To further understand the changes that occurred between 3 and 2 Ga, it is necessary to compare rocks, rock associations, tectonics and geochemistry during and between zircon age peaks. Geochemistry of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution.
DS201802-0258
2018
Piper, J.D.A.Dominant Lid Tectonics behaviour of continental lithosphere in Precambrian times: paleomagnetism confirms prolonged quasi-integrity and absence of supercontinent cycles.Geoscience Frontiers, Vol. 9, 1, pp. 61-89.Mantleplate tectonics

Abstract: Although Plate Tectonics cannot be effectively tested by palaeomagnetism in the Precambrian aeon due to the paucity of high precision poles spanning such a long time period, the possibility of Lid Tectonics is eminently testable because it seeks accordance of the wider dataset over prolonged intervals of time; deficiencies and complexities in the data merely contribute to dispersion. Accordance of palaeomagnetic poles across a quasi-integral continental crust for time periods of up to thousands of millions of years, together with recognition of very long intervals characterised by minimal polar motions (?2.6-2.0, ?1.5-1.25 and ?0.75-0.6 Ga) has been used to demonstrate that Lid Tectonics dominated this aeon. The new PALEOMAGIA database is used to refine a model for the Precambrian lid incorporating a large quasi-integral crescentric core running from South-Central Africa through Laurentia to Siberia with peripheral cratons subject to reorganisation at ?2.1, ?1.6 and ?1.1 Ga. The model explains low levels of tidal friction, reduced heat balance, unique petrologic and isotopic signatures, and the prolonged crustal stability of Earth's “Middle Age”, whilst density concentrations of the palaeomagnetic poles show that the centre of the continental lid was persistently focussed near Earth's rotation axis from ?2.8 to 0.6 Ga. The exception was the ?2.7-2.2 Ga interval defined by ?90° polar movements which translated the periphery of the lid to the rotation pole for this quasi-static period, a time characterised by glaciation and low levels of magmatic activity; the ?2.7 Ga shift correlates with key interval of mid-Archaean crustal growth to some 60-70% of the present volume and REE signatures whilst the ?2.2 Ga shift correlates with the Lomagundi ?13 C and Great Oxygenation events. The palaeomagnetic signature of breakup of the lid at ?0.6 Ga is recorded by the world-wide Ediacaran development of passive margins and associated environmental signatures of new ocean basins. This event defined the end of a dominant Lid Tectonic phase in the history of Earth's continental lithosphere recorded by the quasi-integral Precambrian supercontinent Palaeopangaea and the beginning of the comprehensive Plate Tectonics which has characterised the Phanerozoic aeon. Peripheral modifications to the lid achieved a symmetrical and hemispheric shape in Neoproterozoic times comparable to the familiar short-lived supercontinent (Neo)Pangaea (?350-150 Ma) and this appears to be the sole supercontinent cycle recorded by the palaeomagnetic record. Prolonged integrity of a large continental nucleus accompanied by periodic readjustments of peripheral shields can reconcile divergent tectonic analyses of Precambrian times which on the one hand propose multiple Wilson Cycles to explain some signatures of Plate Tectonics, and alternative interpretations which consider that Plate Tectonics did not commence until the end of the Neoproterozoic.
DS201803-0483
2018
Verard, C.Plate tectonic modelling: review and perspectives.Geological Magazine, in press available GlobalPlate tectonics

Abstract: Since the 1970s, numerous global plate tectonic models have been proposed to reconstruct the Earth's evolution through deep time. The reconstructions have proven immensely useful for the scientific community. However, we are now at a time when plate tectonic models must take a new step forward. There are two types of reconstructions: those using a ‘single control’ approach and those with a ‘dual control’ approach. Models using the ‘single control’ approach compile quantitative and/or semi-quantitative data from the present-day world and transfer them to the chosen time slices back in time. The reconstructions focus therefore on the position of tectonic elements but may ignore (partially or entirely) tectonic plates and in particular closed tectonic plate boundaries. For the readers, continents seem to float on the Earth's surface. Hence, the resulting maps look closer to what Alfred Wegener did in the early twentieth century and confuse many people, particularly the general public. With the ‘dual control’ approach, not only are data from the present-day world transferred back to the chosen time slices, but closed plate tectonic boundaries are defined iteratively from one reconstruction to the next. Thus, reconstructions benefit from the wealth of the plate tectonic theory. They are physically coherent and are suited to the new frontier of global reconstruction: the coupling of plate tectonic models with other global models. A joint effort of the whole community of geosciences will surely be necessary to develop the next generation of plate tectonic models.
DS201804-0677
2018
Caamano-Alegre, M.Drift theory and plate tectonics: a case of embedding in geology.Foundations of Science, Vol. 23, pp. 17-35.Mantleplate tectonics

Abstract: The purpose of this paper is to elucidate the semantic relation between continental drift and plate tectonics. The numerous attempts to account for this case in either Kuhnian or Lakatosian terms have been convincingly dismissed by Rachel Laudan (PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association. Symposia and Invited Papers, 1978), who nevertheless acknowledged that there was not yet a plausible alternative to explain the so called "geological revolution". Several decades later, the epistemological side of this revolution has received much attention (Ruse in The darwinian paradigm, essays on its history, philosophy and religious implications. London, Routledge, 1981/1989; Thagard in Conceptual revolutions. Princeton University Press, Princeton, 1992; Marvin in Metascience 10:208-217, 2001; Oreskes in Plate tectonics: an insiders’ history of the modern theory of the earth. Westview Press, Boulder, 2003), while the semantic relation between drift theory and plate tectonics has remained mainly unexplored. In studying this case under a new light, the notion of embedding, as distinguished from other sorts of intertheoretical relations (Moulines in Cognitio Humana-Dynamik des Wissens und der Werte. XVII, Institut für Philosophie der Universität Leipzig, Leipzig, 1996, Time, chance, and reduction: philosophical aspects of statistical mechanics. Cambridge University Press, Cambridge, 2010, Metatheoria 1(2):11-27, 2011), will have a particular significance. After formally analyzing the relationship between continental drift and plate tectonics, it will become evident that the models of drift theory are part of the models of plate tectonics, thereby fulfilling the conditions for embedding. All theoretical concepts from drift theory are presupposed in some theoretical concepts from plate tectonics, and all empirical concepts of the former are shared by the latter. Furthermore, all the successful paradigmatic applications of continental drift are also successful applications of plate tectonics. As a consequence, under the label "geological revolution", we actually find a salient historical case of cumulative progress across theory change.
DS201804-0708
2018
Kiraly, A., Holt, A.F., Funiciello, F., Faccenna, C., Capitanio, F.A.Modeling slab-slab interactions: dynamics of outward dipping double sided subduction systems.Geochemistry, Geophysics, Geosystems, 22p. PdfMantleplate tectonics

Abstract: Slab?slab interaction is a characteristic feature of tectonically complex areas. Outward dipping double?sided subduction is one of these complex cases, which has several examples on Earth, most notably the Molucca Sea and Adriatic Sea. This study focuses on developing a framework for linking plate kinematics and slab interactions in an outward dipping subduction geometry. We used analog and numerical models to better understand the underlying subduction dynamics. Compared to a single subduction model, double?sided subduction exhibits more time?dependent and vigorous toroidal flow cells that are elongated (i.e., not circular). Because both the Molucca and Adriatic Sea exhibit an asymmetric subduction configuration, we also examine the role that asymmetry plays in the dynamics of outward dipping double?sided subduction. We introduce asymmetry in two ways; with variable initial depths for the two slabs (geometric asymmetry), and with variable buoyancy within the subducting plate (mechanical asymmetry). Relative to the symmetric case, we probe how asymmetry affects the overall slab kinematics, whether asymmetric behavior intensifies or equilibrates as subduction proceeds. While initial geometric asymmetry disappears once the slabs are anchored to the 660 km discontinuity, the mechanical asymmetry can cause more permanent differences between the two subduction zones. In the most extreme case, the partly continental slab stops subducting due to the unequal slab pull force. The results show that the slab?slab interaction is most effective when the two trenches are closer than 10-8 cm in the laboratory, which is 600-480 km when scaled to the Earth.
DS201804-0720
2018
Meinhold, G., Celal Sengor, A.M.A historical account of how continental drift and plate tectonics provided the framework for our current understanding of paleogeography.Geological Magazine, Mar. 19, 26p. PdfMantleplate tectonics

Abstract: Palaeogeography is the cartographic representation of the past distribution of geographic features such as deep oceans, shallow seas, lowlands, rivers, lakes and mountain belts on palinspastically restored plate tectonic base maps. It is closely connected with plate tectonics which grew from an earlier theory of continental drift and is largely responsible for creating and structuring the Earth's lithosphere. Today, palaeogeography is an integral part of the Earth sciences curriculum. Commonly, with some exceptions, only the most recent state of research is presented; the historical aspects of how we actually came to the insights which we take for granted are rarely discussed, if at all. It is remarkable how much was already known about the changing face of the Earth more than three centuries before the theory of plate tectonics, despite the fact that most of our present analytical tools or our models were unavailable then. Here, we aim to present a general conspectus from the dawn of ‘palaeogeography’ in the 16th century onwards. Special emphasis is given to innovative ideas and scientific milestones, supplemented by memorable anecdotes, which helped to advance the theories of continental drift and plate tectonics, and finally led to the establishment of palaeogeography as a recognized discipline of the Earth sciences.
DS201805-0991
2018
Wang, S.Absolute plate motions relative to deep mantle plumes.Earth Planetary Science Letters, Vol. 490, 1, pp. 88-99.Chinaplate tectonics

Abstract: Advances in whole waveform seismic tomography have revealed the presence of broad mantle plumes rooted at the base of the Earth's mantle beneath major hotspots. Hotspot tracks associated with these deep mantle plumes provide ideal constraints for inverting absolute plate motions as well as testing the fixed hotspot hypothesis. In this paper, 27 observed hotspot trends associated with 24 deep mantle plumes are used together with the MORVEL model for relative plate motions to determine an absolute plate motion model, in terms of a maximum likelihood optimization for angular data fitting, combined with an outlier data detection procedure based on statistical tests. The obtained T25M model fits 25 observed trends of globally distributed hotspot tracks to the statistically required level, while the other two hotspot trend data (Comores on Somalia and Iceland on Eurasia) are identified as outliers, which are significantly incompatible with other data. For most hotspots with rate data available, T25M predicts plate velocities significantly lower than the observed rates of hotspot volcanic migration, which cannot be fully explained by biased errors in observed rate data. Instead, the apparent hotspot motions derived by subtracting the observed hotspot migration velocities from the T25M plate velocities exhibit a combined pattern of being opposite to plate velocities and moving towards mid-ocean ridges. The newly estimated net rotation of the lithosphere is statistically compatible with three recent estimates, but differs significantly from 30 of 33 prior estimates.
DS201807-1515
2018
McKenzie, D.A geologist reflects on a long career. Plate tectonics, geotherms, convectionAnnual Review of Earth and Planetary Sciences, Vol. 46, pp. 1-20.Globalplate tectonics

Abstract: Fifty years ago Jason Morgan and I proposed what is now known as the theory of plate tectonics, which brought together the ideas of continental drift and sea floor spreading into what is probably their final form. I was twenty-five and had just finished my PhD. The success of the theory marked the beginning of a change of emphasis in the Earth sciences, which I have spent the rest of my career exploring. Previously geophysicists had principally been concerned with using ideas and techniques from physics to make measurements. But the success of plate tectonics showed that it could also be used to understand and model geological processes. This essay is concerned with a few such efforts in which I have been involved: determining the temperature structure and rheology of the oceanic and continental lithosphere, and with how mantle convection maintains the plate motions and the long-wavelength part of the Earth's gravity field. It is also concerned with how such research is supported.
DS201809-1990
2018
Arndt, N., Roman, A.Numerical modelling reveals weaknesses in the sagduction model for the formation of Archean continental crust: relevance to the onset of plate tectonics.Goldschmidt Conference, 1p. AbstractMantleplate tectonics

Abstract: Recent studies conclude that plate tectonics started 3 b.y. ago in the mid Archean. A transition from a "presubduction" regime to modern plate tectonics is said to be marked by changes in trace-element or isotopic ratios, the appearance of eclogitic inclusions in diamonds, or an apparent change in upper crust composition. Behind these arguments is the notion that subduction was intermittent or impossible early in Earth history when the mantle was hotter. If so, a mechanism other than subduction must have created granitoids of Archean continental crust. In the sagduction model, the base of thick oceanic crust converts to eclogite, founders, and melts to generate granitic magma. Here we evaluate two crucial constraints on the sagduction process: to generate granitic magma requires that water and basalt is taken deep into the mantle; thick oceanic crust is internally differentiated into uppermost layers of hydrated basalt and lower mafic-ultramafic cumulates. Our numerical modelling shows that any deformation within thick, differentiated crust is restricted to the lower cumulates that lack ingredients essential to generate granitic magma. Emplacement of hot intrusions heats the lower crust which was hot and anhydrous. We conclude that the sagduction model is flawed. Recent re-evaluation gives temperatures in ambient Archean upper mantle only moderately higher than in modern mantle, which deflates arguments that subduction was impossible in the Archean. We conclude that Archean continental crust was generated in subduction zones and that plate tectonics started in the early Archean.
DS201809-2090
2018
Smit, K.V., Shirey, S.B.Diamonds help solve the enigma of Earth's deep water.Gems & Gemology, Vol. 54, 2, pp. 220-223.Mantlesubduction, water, plate tectonics

Abstract: Water is carried down into Earth at subduction zones by the process of plate tectonics. Much of the water escapes close behind the subduction zone, promoting melting of the mantle and giving rise to the volcanic chains in the Pacific Ocean basin known as the Ring of Fire, and many other volcanoes elsewhere. But can water be carried even further into the mantle? How would we even know? Why is it important, and what are the effects of such deep water storage? Diamonds can give us the answers to these questions. Recent discoveries of water-containing mineral inclusions and even free water held at high pressures in diamonds tell us that water is carried into Earth’s deep interior—perhaps as deep as 700 km.
DS201811-2580
2018
Hawkesworth, C.J., Brown, M.Earth dynamics and the development of plate tectonics.Philosophical Transactions Royal Society A, Vol. A376: doi://dx.doi.org/10.1098/rsta.2018.0228 5p.Mantleplate tectonics

Abstract: "Why does Earth have plate tectonics?" stands among the top research questions in the Earth Sciences. Plate tectonics developed in the last 4 billion years. This meeting will explore the evidence for the development of plate tectonics, contrast the terrestrial record with those from neighbouring planets, evaluate the conditions required for plate tectonics, and discuss implications for environmental conditions and development of the biosphere.
DS201811-2589
2017
Lenardic, A.The diversity of tectonic modes and thoughts about transitions between them.Philosophical Transactions Royal Society A, Vol. A376: doi://dx.doi.org/10.1098/rsta.2017.0416 23p.Mantleplate tectonics

Abstract: Plate tectonics is a particular mode of tectonic activity that characterizes the present-day Earth. It is directly linked to not only tectonic deformation but also magmatic/volcanic activity and all aspects of the rock cycle. Other terrestrial planets in our Solar System do not operate in a plate tectonic mode but do have volcanic constructs and signs of tectonic deformation. This indicates the existence of tectonic modes different from plate tectonics. This article discusses the defining features of plate tectonics and reviews the range of tectonic modes that have been proposed for terrestrial planets to date. A categorization of tectonic modes relates to the issue of when plate tectonics initiated on Earth as it provides insights into possible pre-plate tectonic behaviour. The final focus of this contribution relates to transitions between tectonic modes. Different transition scenarios are discussed. One follows classic ideas of regime transitions in which boundaries between tectonic modes are determined by the physical and chemical properties of a planet. The other considers the potential that variations in temporal evolution can introduce contingencies that have a significant effect on tectonic transitions. The latter scenario allows for the existence of multiple stable tectonic modes under the same physical/chemical conditions. The different transition potentials imply different interpretations regarding the type of variable that the tectonic mode of a planet represents. Under the classic regime transition view, the tectonic mode of a planet is a state variable (akin to temperature). Under the multiple stable modes view, the tectonic mode of a planet is a process variable. That is, something that flows through the system (akin to heat). The different implications that follow are discussed as they relate to the questions of when did plate tectonics initiate on Earth and why does Earth have plate tectonics.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
DS201811-2604
2018
Richetti, P.C., Schmitt, R.S., Reeves, C.Dividing the South American continent to fit a Gondwana reconstruction: A model based on continental geology.Tectonophysics, Vol. 747-748, pp. 79-98.South Americaplate tectonics

Abstract: The South American continental plate has been affected by intraplate deformation since the start of West Gondwana disruption in the Lower Cretaceous (about 140?Ma). That the present shape of South America is not precisely the same as its shape in reassembled Gondwana partly explains the imperfect fits of the conjugate margins of the South Atlantic proposed since the first reconstruction models of the early 20th century. Several attempts at defining subplates within South America have been published but not all take account of existing knowledge of its continental geology. Here a subdivision into eight rigid subplates is proposed, based primarily on geological and tectonic evidence. Our model is tested against three published models of a multi-subplate Africa, as re-shaped to the pre-breakup outline of that continent, by visual fitting and the use of piercing points. The South America blocks were rotated and the Euler poles calculated interactively in reconstruction software. All three proposed fits had overlapping block margins within South America, indicating post-breakup rifting, except for the Transbrasiliano lineament. This NNE-SSW crustal-scale shear zone was used as a boundary for seven of the eight blocks. It is clearly the main intraplate accommodation zone in South America and an important piercing point in relation to the Kandi lineament in West Africa. The other block boundaries correspond to narrow zones with sedimentary basins and/or dyke swarms that have developed since South Atlantic opening. Each fit required a different configuration of the South America subplates since the pre-rift disposition of the African subplates also differ from each other, contributing to the uncertainty in any detailed reassembly.
DS201812-2801
2017
Dhuime, B., Hawkesworth, C.J., Delavault, H., Cawood, P.A.Rates of generation and destruction of the continental crust: implications for continental growth.Philosphical Transactions of the Royal Society, http://dx.doi.org/ 10.1098/rsta .2017.0403 12p. AvailableMantleplate tectonics

Abstract: Less than 25% of the volume of the juvenile continental crust preserved today is older than 3?Ga, there are no known rocks older than approximately 4?Ga, and yet a number of recent models of continental growth suggest that at least 60-80% of the present volume of the continental crust had been generated by 3?Ga. Such models require that large volumes of pre-3?Ga crust were destroyed and replaced by younger crust since the late Archaean. To address this issue, we evaluate the influence on the rock record of changing the rates of generation and destruction of the continental crust at different times in Earth's history. We adopted a box model approach in a numerical model constrained by the estimated volumes of continental crust at 3?Ga and the present day, and by the distribution of crust formation ages in the present-day crust. The data generated by the model suggest that new continental crust was generated continuously, but with a marked decrease in the net growth rate at approximately 3?Ga resulting in a temporary reduction in the volume of continental crust at that time. Destruction rates increased dramatically around 3 billion years ago, which may be linked to the widespread development of subduction zones. The volume of continental crust may have exceeded its present value by the mid/late Proterozoic. In this model, about 2.6-2.3 times of the present volume of continental crust has been generated since Earth's formation, and approximately 1.6-1.3 times of this volume has been destroyed and recycled back into the mantle.
DS201812-2817
2018
Heron, P.J., Pysklywec, R.N., Stephenson, R.Exploring the theory of plate tectonics: the role of mantle lithosphere structure.http://sp.lyellcollection.org, doi.org/10.1144/ SP470.7Mantleplate tectonics

Abstract: This review of the role of the mantle lithosphere in plate tectonic processes collates a wide range of recent studies from seismology and numerical modelling. A continually growing catalogue of deep geophysical imaging has illuminated the mantle lithosphere and generated new interpretations of how the lithosphere evolves. We review current ideas about the role of continental mantle lithosphere in plate tectonic processes. Evidence seems to be growing that scarring in the continental mantle lithosphere is ubiquitous, which implies a reassessment of the widely held view that it is the inheritance of crustal structure only (rather than the lithosphere as a whole) that is most important in the conventional theory of plate tectonics (e.g. the Wilson cycle). Recent studies have interpreted mantle lithosphere heterogeneities to be pre-existing structures and, as such, linked to the Wilson cycle and inheritance. We consider the current fundamental questions in the role of the mantle lithosphere in causing tectonic deformation, reviewing recent results and highlighting the potential of the deep lithosphere in infiltrating every aspect of plate tectonics processes.
DS201812-2839
2018
Lenardic, A.The diversity of tectonic modes and thoughts about transitions between them.Philosphical Transactions of the Royal Society, Aug. 9, http://dx.doi.org/10.1098/rsta.2017.0416 23p.Mantleplate tectonics
DS201812-2857
2018
Nebel, O., Capitanio, F.A., Moyen, J-F., Weinberg, R.F., Clos, F., Nebel-Jacobsen, Y.J., Cawood, P.A.When crust comes of age: on the chemical evolution of Archaean, felsic continental crust by crustal drip tectonics.Philosphical Transactions of the Royal Society, doi.org/10.1098 / rsta.2018.0103 21p.Mantleplate tectonics

Abstract: The secular evolution of the Earth's crust is marked by a profound change in average crustal chemistry between 3.2 and 2.5?Ga. A key marker for this change is the transition from Archaean sodic granitoid intrusions of the tonalite-trondhjemite-granodiorite (TTG) series to potassic (K) granitic suites, akin (but not identical) to I-type granites that today are associated with subduction zones. It remains poorly constrained as to how and why this change was initiated and if it holds clues about the geodynamic transition from a pre-plate tectonic mode, often referred to as stagnant lid, to mobile plate tectonics. Here, we combine a series of proposed mechanisms for Archaean crustal geodynamics in a single model to explain the observed change in granitoid chemistry. Numeric modelling indicates that upper mantle convection drives crustal flow and subsidence, leading to profound diversity in lithospheric thickness with thin versus thick proto-plates. When convecting asthenospheric mantle interacts with lower lithosphere, scattered crustal drips are created. Under increasing P-T conditions, partial melting of hydrated meta-basalt within these drips produces felsic melts that intrude the overlying crust to form TTG. Dome structures, in which these melts can be preserved, are a positive diapiric expression of these negative drips. Transitional TTG with elevated K mark a second evolutionary stage, and are blends of subsided and remelted older TTG forming K-rich melts and new TTG melts. Ascending TTG-derived melts from asymmetric drips interact with the asthenospheric mantle to form hot, high-Mg sanukitoid. These melts are small in volume, predominantly underplated, and their heat triggered melting of lower crustal successions to form higher-K granites. Importantly, this evolution operates as a disseminated process in space and time over hundreds of millions of years (greater than 200?Ma) in all cratons. This focused ageing of the crust implies that compiled geochemical data can only broadly reflect geodynamic changes on a global or even craton-wide scale. The observed change in crustal chemistry does mark the lead up to but not the initiation of modern-style subduction.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
DS201901-0013
2019
Cawood, P. A., Hawkesworth, C.J.Continental crustal volume, thickness and area, and their geodynamic implications.Gondwana Research, Vol. 66, pp. 116-125.Mantleplate tectonics

Abstract: Models of the volume of continental crust through Earth history vary significantly due to a range of assumptions and data sets; estimates for 3?Ga range from <10% to >120% of present day volume. We argue that continental area and thickness varied independently and increased at different rates and over different periods, in response to different tectonic processes, through Earth history. Crustal area increased steadily on a pre-plate tectonic Earth, prior to ca. 3?Ga. By 3?Ga the area of continental crust appears to have reached a dynamic equilibrium of around 40% of the Earth's surface, and this was maintained in the plate tectonic world throughout the last 3?billion?years. New continental crust was relatively thin and mafic from ca. 4-3?Ga but started to increase substantially with the inferred onset of plate tectonics at ca. 3?Ga, which also led to the sustained development of Earth's bimodal hypsometry. Integration of thickness and area data suggests continental volume increased from 4.5?Ga to 1.8?Ga, and that it remained relatively constant through Earth's middle age (1.8-0.8?Ga). Since the Neoproterozoic, the estimated crustal thickness, and by implication the volume of the continental crust, appears to have decreased by as much as 15%. This decrease indicates that crust was destroyed more rapidly than it was generated. This is perhaps associated with the commencement of cold subduction, represented by low dT/dP metamorphic assemblages, resulting in higher rates of destruction of the continental crust through increased sediment subduction and subduction erosion.
DS201901-0024
2018
Dal Zilio, L., Faccenda, M., Capitanio, F.The role of deep subduction in supercontinent breakup.Tectonophysics, Vol. 746, pp. 312-324.Mantleplate tectonics

Abstract: The breakup of continents and their subsequent drifting plays a crucial role in the Earth's periodic plate aggregation and dispersal cycles. While continental aggregation is considered the result of oceanic closure during subduction, what drives sustained divergence in the following stages remains poorly understood. In this study, thermo-mechanical numerical experiments illustrate the single contribution of subduction and coupled mantle flow to the rifting and drifting of continents. We quantify the drag exerted by subduction-induced mantle flow along the basal surface of continental plates, comparing models of lithospheric slab stagnation above the upper-lower mantle boundary with those where slabs penetrate into the lower mantle. When subduction is upper-mantle confined, divergent basal tractions localise at distances comparable to the effective upper mantle thickness (~ 500 km), causing the opening of a marginal basin. Instead, subduction of lithosphere in the lower mantle reorganises the flow into a much wider cell localising extensional stresses at greater distances from the trench (~ 3000 km). Sub-continental tractions are higher and more sustained over longer time periods in this case, and progressively increase as the slab sinks deeper. Although relatively low, basal-shear stresses when integrated over large plates, generate tension forces that may exceed the strength of the continental lithosphere, eventually leading to breakup and opening of a distal basin. The models illustrate the emergence of a similar mechanism, which results in the formation of back-arc basins above upper-mantle confined subduction, and scales to much larger distances for deeper subduction. Examples include the Atlantic Ocean formation and drifting of the South and North American plates during the Mesozoic-Cenozoic Farallon plate subduction.
DS201901-0070
2018
Rolf, T., Capitanio, F.A., Tackley, P.J.Constraints on mantle viscosity structure from continental drift histories in spherical mantle convection models.Tectonophysics, Vol. 746, pp. 339-351.Mantleplate tectonics

Abstract: Earth's continents drift in response to the force balance between mantle flow and plate tectonics and actively change the plate-mantle coupling. Thus, the patterns of continental drift provide relevant information on the coupled evolution of surface tectonics, mantle structure and dynamics. Here, we investigate rheological controls on such evolutions and use surface tectonic patterns to derive inferences on mantle viscosity structure on Earth. We employ global spherical models of mantle convection featuring self-consistently generated plate tectonics, which are used to compute time-evolving continental configurations for different mantle and lithosphere structures. Our results highlight the importance of the wavelength of mantle flow for continental configuration evolution. Too strong short-wavelength components complicate the aggregation of large continental clusters, while too stable very long wavelength flow tends to enforce compact supercontinent clustering without reasonable dispersal frequencies. Earth-like continental drift with episodic collisions and dispersals thus requires a viscosity structure that supports long-wavelength flow, but also allows for shorter-wavelength contributions. Such a criterion alone is a rather permissive constraint on internal structure, but it can be improved by considering continental-oceanic plate speed ratios and the toroidal-poloidal partitioning of plate motions. The best approximation of Earth's recent tectonic evolution is then achieved with an intermediate lithospheric yield stress and a viscosity structure in which oceanic plates are ? 103 × more viscous than the characteristic upper mantle, which itself is ? 100-200 × less viscous than the lowermost mantle. Such a structure causes continents to move on average ? (2.2 ± 1.0) × slower than oceanic plates, consistent with estimates from present-day and from plate reconstructions. This does not require a low viscosity asthenosphere globally extending below continental roots. However, this plate speed ratio may undergo strong fluctuations on timescales of several 100 Myr that may be linked to periods of enhanced continental collisions and are not yet captured by current tectonic reconstructions.
DS201901-0082
2018
Steinberger, B., Becker, T.W.A comparison of lithospheric thickness models.Tectonophysics, Vol. 746, pp. 325-238.Mantleplate tectonics

Abstract: The outermost layer of the solid Earth consists of relatively rigid plates whose horizontal motions are well described by the rules of plate tectonics. Yet, the thickness of these plates is poorly constrained, with different methods giving widely discrepant results. Here a recently developed procedure to derive lithospheric thickness from seismic tomography with a simple thermal model is discussed. Thickness is calibrated such that the average as a function of seafloor age matches the theoretical curve for half-space cooling. Using several recent tomography models, predicted thickness agrees quite well with what is expected from half-space cooling in many oceanic areas younger than ? 110 Myr. Thickness increases less strongly with age for older oceanic lithosphere, and is quite variable on continents, with thick lithosphere up to ? 250 km inferred for many cratons. Results are highly correlated for recent shear-wave tomography models. Also, comparison to previous approaches based on tomography shows that results remain mostly similar in pattern, although somewhat more variable in the mean value and amount of variation. Global correlations with and between lithosphere thicknesses inferred from receiver functions or heat flow are much lower. However, results inferred from tomography and elastic thickness are correlated highly, giving additional confidence in these patterns of thickness variations, and implying that tomographically inferred thickness may correlate with depth-integrated strength. Thermal scaling from seismic velocities to temperatures yields radial profiles that agree with half-space cooling over large parts of their depth range, in particular for averaged profiles for given lithosphere thickness ranges. However, strong deviations from half-space cooling profiles are found in thick continental lithosphere above depth ? 150 km, most likely due to compositional differences.
DS201902-0269
2019
Domeier, M., Torsvik, T.H.Full plate modelling in pre-Jurassic time.Geological Magazine, Vol. 156, 2, pp. 261-280.Mantleplate tectonics

Abstract: A half-century has passed since the dawning of the plate tectonic revolution, and yet, with rare exception, palaeogeographic models of pre-Jurassic time are still constructed in a way more akin to Wegener's paradigm of continental drift. Historically, this was due to a series of problems - the near-complete absence of in situ oceanic lithosphere older than 200 Ma, a fragmentary history of the latitudinal drift of continents, unconstrained longitudes, unsettled geodynamic concepts and a lack of efficient plate modelling tools - which together precluded the construction of plate tectonic models. But over the course of the last five decades strategies have been developed to overcome these problems, and the first plate model for pre-Jurassic time was presented in 2002. Following on that pioneering work, but with a number of significant improvements (most notably longitude control), we here provide a recipe for the construction of full-plate models (including oceanic lithosphere) for pre-Jurassic time. In brief, our workflow begins with the erection of a traditional (or ‘Wegenerian’) continental rotation model, but then employs basic plate tectonic principles and continental geology to enable reconstruction of former plate boundaries, and thus the resurrection of lost oceanic lithosphere. Full-plate models can yield a range of testable predictions that can be used to critically evaluate them, but also novel information regarding long-term processes that we have few (or no) alternative means of investigating, thus providing exceptionally fertile ground for new exploration and discovery.
DS201902-0299
2019
Meinhold, G., Celal Sengor, A.M.A historical account of how continental drift and plate tectonics provided the framework for our current understanding of palaeogeography.Geological Magazine, Vol. 156, 2, pp. 182-207.Mantleplate tectonics

Abstract: Palaeogeography is the cartographic representation of the past distribution of geographic features such as deep oceans, shallow seas, lowlands, rivers, lakes and mountain belts on palinspastically restored plate tectonic base maps. It is closely connected with plate tectonics which grew from an earlier theory of continental drift and is largely responsible for creating and structuring the Earth's lithosphere. Today, palaeogeography is an integral part of the Earth sciences curriculum. Commonly, with some exceptions, only the most recent state of research is presented; the historical aspects of how we actually came to the insights which we take for granted are rarely discussed, if at all. It is remarkable how much was already known about the changing face of the Earth more than three centuries before the theory of plate tectonics, despite the fact that most of our present analytical tools or our models were unavailable then. Here, we aim to present a general conspectus from the dawn of ‘palaeogeography’ in the 16th century onwards. Special emphasis is given to innovative ideas and scientific milestones, supplemented by memorable anecdotes, which helped to advance the theories of continental drift and plate tectonics, and finally led to the establishment of palaeogeography as a recognized discipline of the Earth sciences.
DS201902-0312
2018
Richards, M.A., Lenardic, A.The Cathles Parameter ( Ct): a geodynamic definition of the asthenosphere and implications for the nature of plate tectonics.Geochemistry, Geophysics, Geosystems, Vol. 19, 12, pp. 4858-4875.Mantleplate tectonics

Abstract: The Earth's global system of tectonic plates move over a thin, weak channel (flow?viscosity zone) in the mantle immediately underlying the plates. This weak channel is commonly referred to as the asthenosphere, and its presence accounts for a number of important Earth observations, including isostasy (e.g., support for the uplift of large mountain ranges), the shape of the Earth's gravity field, the response of the Earth's surface to the removal of large ice sheets (postglacial rebound), and the relationship between plate motions and underlying thermal convection in the mantle. In this paper, we show that these phenomena can be understood in terms of a single unifying parameter consisting of the viscosity contrast between the asthenosphere and the underlying mantle, and the cube of the thickness of the asthenosphere. We propose to call this the "Cathles parameter" in recognition of the author who first recognized its importance in postglacial rebound studies.
DS201902-0331
2019
Verard, C.Plate tectonic modelling: review and perspectives.Geological Magazine, Vol. 156, 2, pp. 208-241.Mantleplate tectonics

Abstract: Since the 1970s, numerous global plate tectonic models have been proposed to reconstruct the Earth's evolution through deep time. The reconstructions have proven immensely useful for the scientific community. However, we are now at a time when plate tectonic models must take a new step forward. There are two types of reconstructions: those using a ‘single control’ approach and those with a ‘dual control’ approach. Models using the ‘single control’ approach compile quantitative and/or semi-quantitative data from the present-day world and transfer them to the chosen time slices back in time. The reconstructions focus therefore on the position of tectonic elements but may ignore (partially or entirely) tectonic plates and in particular closed tectonic plate boundaries. For the readers, continents seem to float on the Earth's surface. Hence, the resulting maps look closer to what Alfred Wegener did in the early twentieth century and confuse many people, particularly the general public. With the ‘dual control’ approach, not only are data from the present-day world transferred back to the chosen time slices, but closed plate tectonic boundaries are defined iteratively from one reconstruction to the next. Thus, reconstructions benefit from the wealth of the plate tectonic theory. They are physically coherent and are suited to the new frontier of global reconstruction: the coupling of plate tectonic models with other global models. A joint effort of the whole community of geosciences will surely be necessary to develop the next generation of plate tectonic models.
DS201904-0743
2019
Hartnady, M.I.H., Kirkland, C.L.A gradual transition to plate tectonics on Earth between 3.2 and 2.7 billion years ago.Terra Nova, Vol. 31, 2, pp. 129-134.Mantleplate tectonics

Abstract: Zircon crystals precipitated from granitoid magmas contain a robust record of the age and chemistry of continental magmatism spanning some 4.375 Ga of Earth history, a record that charts initiation of plate tectonics. However, constraining when exactly plate tectonics began to dominate crustal growth processes is challenging as the geochemical signatures of individual rocks may reflect local subduction processes rather than global plate tectonics. Here we apply counting statistics to a global database of coupled U-Pb and Hf isotope analyses on magmatic zircon grains from continental igneous and sedimentary rocks to quantify changes in the compositions of their source rocks. The analysis reveals a globally significant change in the sources of granitoid magmas between 3.2 and 2.7 Ga. These secular changes in zircon chemistry are driven by a coupling of the deep (depleted mantle) and shallow (crustal) Earth reservoirs, consistent with a geodynamic regime dominated by Wilson cycle style plate tectonics.
DS201904-0745
2019
Honing, D., Tosi, N., Hansen-Goos, H., Spohn, T.Bifurcation in the growth of continental crust. (Water-land ratio)Physics of the Earth and Planetary Interiors, Vol. 287, pp. 37-50.Mantleplate tectonics

Abstract: Is the present-day water-land ratio a necessary outcome of the evolution of plate tectonic planets with a similar age, volume, mass, and total water inventory as the Earth? This would be the case - largely independent of initial conditions - if Earth’s present-day continental volume were at a stable unique equilibrium with strong self-regulating mechanisms of continental growth steering the evolution to this state. In this paper, we question this conjecture. Instead we suggest that positive feedbacks in the plate tectonics model of continental production and erosion may dominate and show that such a model can explain the history of continental growth. We investigate the main mechanisms that contribute to the growth of the volume of the continental crust. In particular, we analyze the effect of the oceanic plate speed, depending on the area and thickness of thermally insulating continents, on production and erosion mechanisms. Effects that cause larger continental production rates for larger values of continental volume are positive feedbacks. In contrast, negative feedbacks act to stabilize the continental volume. They are provided by the increase of the rate of surface erosion, subduction erosion, and crustal delamination with the continental volume. We systematically analyze the strengths of positive and negative feedback contributions to the growth of the continental crust. Although the strengths of some feedbacks depend on poorly known parameters, we conclude that a net predominance of positive feedbacks is plausible. We explore the effect of the combined feedback strength on the feasibility of modeling the observed small positive net continental growth rate over the past 2-3 billion years. We show that a model with dominating positive feedbacks can readily explain this observation in spite of the cooling of the Earth’s mantle acting to reduce the continental production rate. In contrast, explaining this observation using a model with dominating negative feedbacks would require the continental erosion and production rates to both have the same or a sufficiently similar functional dependence on the thermal state of the mantle, which appears unreasonable considering erosion to be largely dominated by the surface relief and weathering. The suggested scenario of dominating positive feedbacks implies that the present volume of the continental crust and its evolution are strongly determined by initial conditions. Therefore, exoplanets with Earth-like masses and total water inventories may substantially differ from the Earth with respect to their relative land/surface ratios and their habitability.
DS201905-1017
2019
Boger, S.D., Maas, R., Pastuhov, M., Macey, P.H., Hirdes, W., Schulte, B., Fanning, C.M., Ferreira, C.A.M., Jenett, T., Dallwig, R.The tectonic domains of southern and western Madagascar.Precambrian Research, Vol. 327, pp. 144-175.Africa, Madagascarplate tectonics

Abstract: Southern and western Madagascar is comprised of five tectonic provinces that, from northeast to southwest, are defined by the: (i) Ikalamavony, (ii) Anosyen, (iii) Androyen, (iv) Graphite and (v) Vohibory Domains. The Ikalamavony, Graphite and Vohibory Domains all have intermediate and felsic igneous protoliths of tonalite-trondhjemite-granodiorite-granite composition, with positive ?Nd, and low Sr and Pb isotopic ratios. All three domains are interpreted to be the products of intra-oceanic island arc magmatism. The protoliths of the Ikalamavony and Graphite Domains formed repectively between c. 1080-980?Ma and 1000-920?Ma, whereas those of the Vohibory Domain are younger and date to between c. 670-630?Ma. Different post-formation geologic histories tie the Vohibory-Graphite and Ikalamavony Domains to opposite sides of the pre-Gondwana Mozambique Ocean. By contrast, the Androyen and Anosyen Domains record long crustal histories. Intermediate to felsic igneous protoliths in the Androyen Domain are of Palaeoproterozoic age (c. 2200-1800?Ma), of tonalite-trondhjemite-granodiorite-granite composition, and show negative ?Nd, moderate to high 87Sr/86Sr and variable Pb isotopic compositions. The felsic igneous protoliths of the Anosyen Domain are of granitic composition and, when compared to felsic gneisses of the Androyen Domain, show consistently lower Sr/Y and markedly higher Sr and Pb isotope ratios. Like the Vohibory and Graphite Domains, the Androyen Domain can be linked to the western side of the Mozambique Ocean, while the Anosyen Domain shares magmatic and detrital zircon commonalities with the Ikalamavony Domain. It is consequently linked to the opposing eastern side of this ocean. The first common event observed in all domains dates to c. 580-520?Ma and marks the closure of the Mozambique Ocean. The trace of this suture lies along the boundary between the Androyen and Anosyen Domains and is defined by the Beraketa high-strain zone.
DS201905-1040
2019
Hartmann, J. Plate tectonics, carbon, and climate.Science, Vol. 364, 6436, pp. 126-127.Mantleplate tectonics

Abstract: Over the past 541 million years (the Phanerozoic eon), Earth's climate has been relatively stable compared to preceding eons. However, there have been periods of longer glaciations, which have been attributed to changes in the balance between CO2 sources and sinks. The major CO2 sources are thought to be mantle degassing at hotspot volcanoes, mid-ocean ridges, and rifts; subduction zone volcanoes; metamorphosis of carbonate rocks into silicate rocks; and oxidative weathering (see the figure) (1). The main CO2 sink is chemical weathering and the subsequent transfer of carbon to the ocean, where carbonate sediments lock up CO2 for long periods of time. During arc-continent collisions, rocks from volcanic arcs are accreted to continents. On page 181 of this issue, Macdonald et al. (2) propose that weathering can rise after the accreted rocks are exposed at Earth's surface. This mechanism may explain the glaciations seen during the Phanerozoic.
DS201906-1312
2019
Lambert, S., Koornneef, J.M., Millet, M-A., Davies, G.R., Cook, M., Lissenberg, C.J.Highly heterogeneous depleted mantle recorded in the lower oceanic crust. ( MAR)Nature Geoscience, https://doi.org/10.1038/s41561-019-0368-9 8p.Mantleplate tectonics

Abstract: The Earth’s mantle is heterogeneous as a result of early planetary differentiation and subsequent crustal recycling during plate tectonics. Radiogenic isotope signatures of mid-ocean ridge basalts have been used for decades to map mantle composition, defining the depleted mantle endmember. These lavas, however, homogenize via magma mixing and may not capture the full chemical variability of their mantle source. Here, we show that the depleted mantle is significantly more heterogeneous than previously inferred from the compositions of lavas at the surface, extending to highly enriched compositions. We perform high-spatial-resolution isotopic analyses on clinopyroxene and plagioclase from lower crustal gabbros drilled on a depleted ridge segment of the northern Mid-Atlantic Ridge. These primitive cumulate minerals record nearly the full heterogeneity observed along the northern Mid-Atlantic Ridge, including hotspots. Our results demonstrate that substantial mantle heterogeneity is concealed in the lower oceanic crust and that melts derived from distinct mantle components can be delivered to the lower crust on a centimetre scale. These findings provide a starting point for re-evaluation of models of plate recycling, mantle convection and melt transport in the mantle and the crust.
DS201906-1316
2019
Liu, C., Runyon, S.E., Knoll, A.H., Hazen, R.M.The same and not the same: ore geology, mineralogy and geochemistry of Rodinia assembly versus other supercontinents.Earth Science Reviews, doi.org/10.1016 /j.earscrev.2019.05.04Mantleplate tectonics

Abstract: It has been long observed that the amalgamation of supercontinents, including Rodinia, is coeval with peaks of UPb ages of global detrital zircons. However, our new compilation of global geochemical, mineralogical, and ore geologic records shows that the assembly of Rodinia stands out from others, in terms of whole-rock trace element geochemistry, as well as records of mineralogy and ore deposits. During the assembly of Rodinia, Nb, Y, and Zr concentrations were enriched in igneous rocks, with prolific formation of zircon and minerals bearing Th, Nb or Y, and formation of NYF-type pegmatites and REE ore deposits. At the same time, many types of ore deposits are relatively poorly represented in Rodinin terranes, including deposits of orogenic gold, porphyry copper, and volcanic hosted massive sulfide deposits, with a corresponding paucity of many minerals (e.g., minerals bearing Au, Sb, Ni) associated with these deposits. We interpret these records as indicating the prevalence of ‘non-arc’ magmatism and a relative lack of subduction-related arc magma preserved in the surviving pieces of the Rodinia supercontinent, distinct from other episodes of supercontinent assembly. We further attribute the prevalence of ‘non-arc’ magmatism to enhanced asthenosphere-lithosphere interactions in the Mesoproterozoic, and speculate that the lack of ‘arc-collisional’ magma may be related to enhanced erosion of Rodinia orogenic belts.
DS201906-1323
2019
Meredith, A.S., Williams, S.E., Brune, S., Collins, A.S., Muller, R.D.Rift and boundary evolution across two supercontinent cycles. Gondwana, RodiniaGlobal and Planetary Change, Vol. 173, pp. 1-14.Globalplate tectonics

Abstract: The extent of continental rifts and subduction zones through deep geological time provides insights into the mechanisms behind supercontinent cycles and the long term evolution of the mantle. However, previous compilations have stopped short of mapping the locations of rifts and subduction zones continuously since the Neoproterozoic and within a self-consistent plate kinematic framework. Using recently published plate models with continuously closing boundaries for the Neoproterozoic and Phanerozoic, we estimate how rift and peri-continental subduction length vary from 1 Ga to present and test hypotheses pertaining to the supercontinent cycle and supercontinent breakup. We extract measures of continental perimeter-to-area ratio as a proxy for the existence of a supercontinent, where during times of supercontinent existence the perimeter-to-area ratio should be low, and during assembly and dispersal it should be high. The amalgamation of Gondwana is clearly represented by changes in the length of peri-continental subduction and the breakup of Rodinia and Pangea by changes in rift lengths. The assembly of Pangea is not clearly defined using plate boundary lengths, likely because its formation resulted from the collision of only two large continents. Instead the assembly of Gondwana (ca. 520 Ma) marks the most prominent change in arc length and perimeter-to-area ratio during the last billion years suggesting that Gondwana during the Early Palaeozoic could explicitly be considered part of a Phanerozoic supercontinent. Consequently, the traditional understanding of the supercontinent cycle, in terms of supercontinent existence for short periods of time before dispersal and re-accretion, may be inadequate to fully describe the cycle. Instead, either a two-stage supercontinent cycle could be a more appropriate concept, or alternatively the time period of 1 to 0 Ga has to be considered as being dominated by supercontinent existence, with brief periods of dispersal and amalgamation.
DS201906-1327
2019
Muller, R.D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, May 5, 36p. Mantleplate tectonics

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic?Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hotspot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 million km2 in the Late Jurassic (~160?155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation it reaches a high of 48 million km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS201906-1328
2019
Murphy, J.B., Quesada, C., Strachan, R.Damian Nance, the supercontinent cycle and much more.GAC/MAC annual Meeting, 1p. Abstract p. 194.Globalplate tectonics

Abstract: Over the past three decades, it has become clear that Pangea was just the most recent of several supercontinents that have amalgamated and dispersed since at least 2.0 Ga. It was fully recognized at the time that the so-called "supercontinent cycle" had a profound effect on Earth Systems, possibly one of the most significant insights since the advent of plate tectonics. In the early 1980's, Damian Nance, along with colleagues Tom Worsley and Judith Moody, were the instigators of this phase of modern thinking and since that time so many international projects and research careers have been spawned by those insights. Although many elegant papers had proposed orogenic episodicity before the acceptance of the plate tectonic paradigm, Damian and colleagues were the first to link such episodicity to a supercontinent cycle. In addition, Damian has made seminal contributions to the understanding of orogenic processes in general, and through his detailed fieldwork, to our foundational knowledge of the geology of the Avalonian belt in Maritime Canada, Paleozoic and Proterozoic complexes in Mexico, recent (Quaternary) tectonics in Greece and even more recent Beam Engine tectonics in Cornwall and the rest of the world. His body of work has had first-order implications for the interpretation of ancient orogens and the processes responsible for them. Most important of all, we have all benefited from the positive impact Damian has had on all our careers and the generosity and collegial approach to research. His influence has extended far beyond his immediate research community as a result of his co-leadership of IGCP projects and his inclusive approach to sharing and developing new avenues in science. He has inspired generations of students and his peers and his legacy is immense.
DS201906-1335
2019
Piccolo, A., Palin, R.M., Kaus, B.J.P., White, R.W.Generation of Earth's early continents from a relatively cool Archean mantle.Geochemistry, Geophysics, Geosystems, Vol. 20, 4, pp. 1679-1697.Mantleplate tectonics

Abstract: It has been believed that early Earth featured higher mantle temperature. The mantle temperature affects the geodynamic processes, and, therefore, the production of the continental crust, which has been a stable environment for the developing of life since Earth's infancy. However, our knowledge of the processes operating during the early Earth is still not definitive. The wide range of the mantle temperature estimation (from 1500 to 1600 °C) hampered our ability to understand early Earth's dynamic and geological data alone cannot provide a definitive answer. Therefore, it is necessary to integrate them with numerical modeling. Our contribution conjugates petrological modeling with thermal?mechanical simulations to unveil the effect of continental crust production. Continental crust's extraction from partially melted hydrated basalts leaves behind dense rocks that sink into the mantle dragging part of surface hydrated rocks. These drips produce a major compositional change of the mantle and promote the production of new basaltic/continental crust. The combination of these processes cools the mantle, suggesting that it could not have been extremely hot for geological timescales. We show that such processes can be active even in a relatively cool mantle (1450-1500 °C), providing new constraints to understand the infancy of our planet.
DS201907-1549
2019
Hoffman, P.F.Big Time. Proterozoic Eon … Annual Reviews of Earth and Planetary Sciences, Vol. 47, pp. 2-19.Globalplate tectonics

Abstract: The Proterozoic Eon was once regarded as the neglected middle half of Earth history. The name refers to early animals, but they did not appear until the eon (2.5-0.54 Ga) was nearly over. Eukaryotic cells and sexual reproduction evolved much earlier in the eon, as did chloroplasts. Molecular dioxygen, the presence of which altered the geochemical behavior of nearly every element essential to life, rose from negligible to near-modern levels, and then plummeted before rising fitfully again. Plate tectonics took on a modern form, and two supercontinents, Nuna and Rodinia, successively congregated and later dispersed. Climate regulatory failures, i.e., Snowball Earth, appear to be a uniquely Proterozoic phenomenon, having occurred twice in rapid succession near the end of the eon (from 717 to 660 Ma and from 650 to 635 Ma) and arguably once near its beginning (ca. 2.43 Ga). Dynamic sea glaciers covered Snowball Earth oceans from pole to pole, and equatorial sublimation drove slow-moving ice sheets on land. Ultimately, the gradual accumulation of CO2 triggered rapid deglaciation and transient greenhouse aftermaths. Physically based and geologically tested, Neoproterozoic Snowball Earth appears to have molecular legacies in ancient bitumens and modern organisms. This is the story of my love affair with an eon that is now a little less neglected.
DS201907-1562
2019
Muller, D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, in press available, 37p.Africa, globalplate tectonics, rotation

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic-Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hot spot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model, net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 × 106 km2 in the Late Jurassic (~160-155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation, it reaches a high of 48 x 106 km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS201907-1577
2019
Sobolev, S.V., Brown, M.Surface erosion events controlled the evolution of plate tectonics on Earth.Nature, Vol. 570, June 6, p. 52-57.Mantleplate tectonics

Abstract: Plate tectonics is among the most important geological processes on Earth, but its emergence and evolution remain unclear. Here we extrapolate models of present-day plate tectonics to the past and propose that since about three billion years ago the rise of continents and the accumulation of sediments at continental edges and in trenches has provided lubrication for the stabilization of subduction and has been crucial in the development of plate tectonics on Earth. We conclude that the two largest surface erosion and subduction lubrication events occurred after the Palaeoproterozoic Huronian global glaciations (2.45 to 2.2 billion years ago), leading to the formation of the Columbia supercontinent, and after the Neoproterozoic ‘snowball’ Earth glaciations (0.75 to 0.63 billion years ago). The snowball Earth event followed the ‘boring billion’—a period of reduced plate tectonic activity about 1.75 to 0.75 billion years ago that was probably caused by a shortfall of sediments in trenches—and it kick-started the modern episode of active plate tectonics.
DS201907-1579
2019
Tetley, M.G., Li, Z-X., Matthews, K.J., Williams, S.E., Muller, R.D.Decoding Earth's plate tectonic history using sparse geochemical data.Geoscience Frontiers, available 12p. PdfMantleplate tectonics

Abstract: Accurately mapping plate boundary types and locations through time is essential for understanding the evolution of the plate-mantle system and the exchange of material between the solid Earth and surface environments. However, the complexity of the Earth system and the cryptic nature of the geological record make it difficult to discriminate tectonic environments through deep time. Here we present a new method for identifying tectonic paleo-environments on Earth through a data mining approach using global geochemical data. We first fingerprint a variety of present-day tectonic environments utilising up to 136 geochemical data attributes in any available combination. A total of 38301 geochemical analyses from basalts aged from 5-0 Ma together with a well-established plate reconstruction model are used to construct a suite of discriminatory models for the first order tectonic environments of subduction and mid-ocean ridge as distinct from intraplate hotspot oceanic environments, identifying 41, 35, and 39 key discriminatory geochemical attributes, respectively. After training and validation, our model is applied to a global geochemical database of 1547 basalt samples of unknown tectonic origin aged between 1000-410 Ma, a relatively ill-constrained period of Earth's evolution following the breakup of the Rodinia supercontinent, producing 56 unique global tectonic environment predictions throughout the Neoproterozoic and Early Paleozoic. Predictions are used to discriminate between three alternative published Rodinia configuration models, identifying the model demonstrating the closest spatio-temporal consistency with the basalt record, and emphasizing the importance of integrating geochemical data into plate reconstructions. Our approach offers an extensible framework for constructing full-plate, deep-time reconstructions capable of assimilating a broad range of geochemical and geological observations, enabling next generation Earth system models.
DS201908-1785
2019
Le Pichon, X.Fifty years of plate tectonics afterthoughts of a witness.Tectonics, doi.org/10.1029 / 2018TC005350 27p. PdfGlobalplate tectonics

Abstract: I suggest that the Earth Sciences in the mid?1950's entered a state of supercooling where the smallest input could lead to the simultaneous crystallization of new ideas. I joined in 1959 the Lamont Geological Observatory, one of the hotbeds where the Plate Tectonic revolution germinated. This paper is not an exhaustive history from an unbiased outside observer. It is a report of one of the participants who interacted with quite a few of the main actors of this revolution and who, fifty years later, revisits these extraordinary times. I emphasize the state of confusion and contradiction but also of extraordinary excitement in which we, earth scientists, lived at this time. I will identify several cases of what I consider to be simultaneous appearances of new ideas and will describe what now appear to be incomprehensible failures to jump on apparently obvious conclusions, based on my own experience.
DS201909-2043
2019
Grocholski, B.Super-old mantle plumes.Science, Vol. 365, 6455, p. 770.Mantleplate tectonics

Abstract: Plate tectonics on Earth are linked to the dynamics of the interior today. However, the interior dynamics in the distant past are a far greater mystery because of the subduction of surface rock. Wang et al. analyzed 3.5-billion-year-old rocks in China and discovered the oldest geochemical evidence of mantle plume magmatism along with high mantle temperatures. The rocks also appear to record chemical heterogeneity and may be evidence of convection in the deep mantle 3.5 billion years ago.
DS201909-2046
2019
Holder, R.M., Viete, D.R., Brown, M., Johnson, T.E.Metamorphism and the evolution of plate tectonics.Nature, doi.org/10.1038/ s41586-019-1462-2 2p.Mantleplate tectonics

Abstract: Earth’s mantle convection, which facilitates planetary heat loss, is manifested at the surface as present-day plate tectonics1. When plate tectonics emerged and how it has evolved through time are two of the most fundamental and challenging questions in Earth science1,2,3,4. Metamorphic rocks—rocks that have experienced solid-state mineral transformations due to changes in pressure (P) and temperature (T)—record periods of burial, heating, exhumation and cooling that reflect the tectonic environments in which they formed5,6. Changes in the global distribution of metamorphic (P, T) conditions in the continental crust through time might therefore reflect the secular evolution of Earth’s tectonic processes. On modern Earth, convergent plate margins are characterized by metamorphic rocks that show a bimodal distribution of apparent thermal gradients (temperature change with depth; parameterized here as metamorphic T/P) in the form of paired metamorphic belts5, which is attributed to metamorphism near (low T/P) and away from (high T/P) subduction zones5,6. Here we show that Earth’s modern plate tectonic regime has developed gradually with secular cooling of the mantle since the Neoarchaean era, 2.5 billion years ago. We evaluate the emergence of bimodal metamorphism (as a proxy for secular change in plate tectonics) using a statistical evaluation of the distributions of metamorphic T/P through time. We find that the distribution of metamorphic T/P has gradually become wider and more distinctly bimodal from the Neoarchaean era to the present day, and the average metamorphic T/P has decreased since the Palaeoproterozoic era. Our results contrast with studies that inferred an abrupt transition in tectonic style in the Neoproterozoic era (about 0.7 billion years ago1,7,8) or that suggested that modern plate tectonics has operated since the Palaeoproterozoic era (about two billion years ago9,10,11,12) at the latest.
DS201909-2058
2019
Lenardic, A., Weller, M., Hoink, T., Seales, J.Toward a boot strap hypothesis of plate tectonics: feedbacks between plates, the asthenosphere, and the wavelength of mantle convection.Physics of the Earth and Planetary Interiors, in press avaialable, 72p. PdfMantleplate tectonics

Abstract: The solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature gradient in the mantle which, together with temperature-dependent viscosity, leads to a viscosity increase from the upper to the lower mantle. This allows mantle flow to channelize in a low viscosity region beneath plates (an asthenosphere forms dynamically). Flow channelization, in turn, stabilizes long wavelength convection. The degree of dynamic viscosity variations from the upper to the lower mantle increases with the wavelength of convection and drops toward zero if the system transitions from plate tectonics to a single plate planet. The plate margin strength needed to initiate that transition increases for long wavelength cells (long wavelength flow allows plate tectonics to exist over a wider range of plate margin strength). The coupled feedbacks allow for a linked causality between plates, the asthenosphere, and the wavelength of mantle flow, with none being more fundamental than the others and the existence of each depending on the others. Under this hypothesis, the asthenosphere is defined by an active process, plate tectonics, which maintains it and is maintained by it and plate tectonics is part of an emergent, self-sustaining flow system that bootstraps itself into existence.
DS201909-2067
2018
O'Neill, C., Turner, S., Rushmer, T.The inception of plate tectonics: a record of failure.Philosphical Transactions A, Vol. 376, 29p. PdfMantleplate tectonics

Abstract: The development of plate tectonics from a pre-plate tectonics regime requires both the initiation of subduction and the development of nascent subduction zones into long-lived contiguous features. Subduction itself has been shown to be sensitive to system parameters such as thermal state and the specific rheology. While generally it has been shown that cold-interior high-Rayleigh-number convection (such as on the Earth today) favours plates and subduction, due to the ability of the interior stresses to couple with the lid, a given system may or may not have plate tectonics depending on its initial conditions. This has led to the idea that there is a strong history dependence to tectonic evolution—and the details of tectonic transitions, including whether they even occur, may depend on the early history of a planet. However, intrinsic convective stresses are not the only dynamic drivers of early planetary evolution. Early planetary geological evolution is dominated by volcanic processes and impacting. These have rarely been considered in thermal evolution models. Recent models exploring the details of plate tectonic initiation have explored the effect of strong thermal plumes or large impacts on surface tectonism, and found that these ‘primary drivers’ can initiate subduction, and, in some cases, over-ride the initial state of the planet. The corollary of this, of course, is that, in the absence of such ongoing drivers, existing or incipient subduction systems under early Earth conditions might fail. The only detailed planetary record we have of this development comes from Earth, and is restricted by the limited geological record of its earliest history. Many recent estimates have suggested an origin of plate tectonics at approximately 3.0?Ga, inferring a monotonically increasing transition from pre-plates, through subduction initiation, to continuous subduction and a modern plate tectonic regime around that time. However, both numerical modelling and the geological record itself suggest a strong nonlinearity in the dynamics of the transition, and it has been noted that the early history of Archaean greenstone belts and trondhjemite-tonalite-granodiorite record many instances of failed subduction. Here, we explore the history of subduction failure on the early Earth, and couple these with insights from numerical models of the geodynamic regime at the time.
DS201909-2091
2018
Stern, R.J.The evolution of plate tectonics.Philosphical Transactions A, Vol. 376, 22p.Mantleplate tectonics

Abstract: To understand how plate tectonics became Earth's dominant mode of convection, we need to address three related problems. (i) What was Earth's tectonic regime before the present episode of plate tectonics began? (ii) Given the preceding tectonic regime, how did plate tectonics become established? (iii) When did the present episode of plate tectonics begin? The tripartite nature of the problem complicates solving it, but, when we have all three answers, the requisite consilience will provide greater confidence than if we only focus on the long-standing question of when did plate tectonics begin? Earth probably experienced episodes of magma ocean, heat-pipe, and increasingly sluggish single lid magmatotectonism. In this effort we should consider all possible scenarios and lines of evidence. As we address these questions, we should acknowledge there were probably multiple episodes of plate tectonic and non-plate tectonic convective styles on Earth. Non-plate tectonic styles were probably dominated by ‘single lid tectonics’ and this evolved as Earth cooled and its lithosphere thickened. Evidence from the rock record indicates that the modern episode of plate tectonics began in Neoproterozoic time. A Neoproterozoic transition from single lid to plate tectonics also explains kimberlite ages, the Neoproterozoic climate crisis and the Neoproterozoic acceleration of evolution.
DS201910-2248
2019
Capitanio, F.A., Nebel, O., Cawood, P.A., Weinberg, R.F., Clos, F.Lithosphere differentiation in the early Earth controls Archean tectonics.Earth and Planetary Science letters, Vol. 525, 115755, 12p.Mantleplate tectonics

Abstract: The processes that operated on the early Earth and the tectonic regimes in which it was shaped are poorly constrained, reflecting the highly fragmentary rock record and uncertainty in geodynamic conditions. Most models of early Earth geodynamics invoke a poorly mobile lid regime, involving little or episodic movement of the lithosphere, above a convecting mantle. However, such a regime does not reconcile with the record of Archean tectonics, which displays contrasting environments associated with either non-plate tectonics or plate tectonics. Here, we propose a regime for the early Earth in which progressive melt extraction at sites of divergence led to the formation of large portions of stiffer lithospheric lid, called proto-plates. These proto-plates enabled stress propagation to be focussed at their margins, which were then the locus for extension as oppose to shortening, under-thrusting and thickening to form adjoining proto-cratons. We test this hypothesis embedding lithospheric stiffening during melt extraction in thermo-mechanical models of mantle convection, under conditions that prevailed in the Archean. We demonstrate the emergence of migrating, rigid proto-plates in which regions of prolonged focused compression coexist with remnants of the stagnant lid, thereby reproducing the widespread dichotomy proposed for the Archean tectonic record. These diverse tectonic modes coexist in a single regime that is viable since the Hadean and lasted until the transition to modern plate tectonics.
DS201910-2265
2019
Holder, R., Viete, D.R., Brown, M., Johnson, T.E.Metamorphism and evolution of plate tectonics.Nature, Vol. 572, 7769, pp. 1-4.Mantleplate tectonics

Abstract: Earth’s mantle convection, which facilitates planetary heat loss, is manifested at the surface as present-day plate tectonics1. When plate tectonics emerged and how it has evolved through time are two of the most fundamental and challenging questions in Earth science1,2,3,4. Metamorphic rocks—rocks that have experienced solid-state mineral transformations due to changes in pressure (P) and temperature (T)—record periods of burial, heating, exhumation and cooling that reflect the tectonic environments in which they formed5,6. Changes in the global distribution of metamorphic (P, T) conditions in the continental crust through time might therefore reflect the secular evolution of Earth’s tectonic processes. On modern Earth, convergent plate margins are characterized by metamorphic rocks that show a bimodal distribution of apparent thermal gradients (temperature change with depth; parameterized here as metamorphic T/P) in the form of paired metamorphic belts5, which is attributed to metamorphism near (low T/P) and away from (high T/P) subduction zones5,6. Here we show that Earth’s modern plate tectonic regime has developed gradually with secular cooling of the mantle since the Neoarchaean era, 2.5 billion years ago. We evaluate the emergence of bimodal metamorphism (as a proxy for secular change in plate tectonics) using a statistical evaluation of the distributions of metamorphic T/P through time. We find that the distribution of metamorphic T/P has gradually become wider and more distinctly bimodal from the Neoarchaean era to the present day, and the average metamorphic T/P has decreased since the Palaeoproterozoic era. Our results contrast with studies that inferred an abrupt transition in tectonic style in the Neoproterozoic era (about 0.7 billion years ago1,7,8) or that suggested that modern plate tectonics has operated since the Palaeoproterozoic era (about two billion years ago9,10,11,12) at the latest.
DS201910-2279
2019
Lenardic, A., Weller, M.B., Seales, J., Hoink, T.Toward a boot strap hypothesis of plate tectonics: feedbacks between plate tectonics, the asthenosphere, and the wavelength of mantle convection.Physics of the Earth and Planetary Interiors, in press available, 57p. PdfMantleplate tectonics

Abstract: The solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature gradient in the mantle which, together with temperature-dependent viscosity, leads to a viscosity increase from the upper to the lower mantle. This allows mantle flow to channelize in a low viscosity region beneath plates (an asthenosphere forms dynamically). Flow channelization, in turn, stabilizes long wavelength convection. The degree of dynamic viscosity variations from the upper to the lower mantle increases with the wavelength of convection and drops toward zero if the system transitions from plate tectonics to a single plate planet. The plate margin strength needed to initiate that transition increases for long wavelength cells (long wavelength flow allows plate tectonics to exist over a wider range of plate margin strength). The coupled feedbacks allow for a linked causality between plates, the asthenosphere, and the wavelength of mantle flow, with none being more fundamental than the others and the existence of each depending on the others. Under this hypothesis, the asthenosphere is defined by an active process, plate tectonics, which maintains it and is maintained by it and plate tectonics is part of an emergent, self-sustaining flow system that bootstraps itself into existence.
DS201911-2510
2019
Beaussier, S.J., Gerya, T.V., Burg, J-P.3D numerical modelling of the Wilson cycle: structural inheritance of alternating subduction polarity.N: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, 439-461.Mantleplate tectonics

Abstract: Alternating subduction polarity along suture zones has been documented in several orogenic systems. Yet the mechanisms leading to this geometric inversion and the subsequent interplay between the contra-dipping slabs have been little studied. To explore such mechanisms, 3D numerical modelling of the Wilson cycle was conducted from continental rifting, breakup and oceanic spreading to convergence and self-consistent subduction initiation. In the resulting models, near-ridge subduction initiating with the formation of contra-dipping slab segments is an intrinsically 3D process controlled by earlier convergence-induced ridge swelling. The width of the slab segments is delimited by transform faults inherited from the rifting and ocean floor spreading stages. The models show that the number of contra-dipping slab segments depends mainly on the size of the oceanic basin, the asymmetry of the ridge and variations in kinematic inversion from divergence to convergence. Convergence velocity has been identified as a second-order parameter. The geometry of the linking zone between contra-dipping slab segments varies between two end-members governed by the lateral coupling between the adjacent slab segments: (1) coupled slabs generate wide, arcuate linking zones holding two-sided subduction; and (2) decoupled slabs generate narrow transform fault zones against which one-sided, contra-dipping slabs abut.
DS201911-2515
2019
Dalziel, I.W.D., Dewey, J.F.The classic Wilson Cycle revisited.IN: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 18-38.Mantleplate tectonics

Abstract: In the first application of the developing plate tectonic theory to the pre-Pangaea world 50 years ago, attempting to explain the origin of the Paleozoic Appalachian-Caledonian orogen, J. Tuzo Wilson asked the question: ‘Did the Atlantic close and then reopen?’. This question formed the basis of the concept of the Wilson cycle: ocean basins opening and closing to form a collisional mountain chain. The accordion-like motion of the continents bordering the Atlantic envisioned by Wilson in the 1960s, with proto-Appalachian Laurentia separating from Europe and Africa during the early Paleozoic in almost exactly the same position that it subsequently returned during the late Paleozoic amalgamation of Pangaea, now seems an unlikely scenario. We integrate the Paleozoic history of the continents bordering the present day basin of the North Atlantic Ocean with that of the southern continents to develop a radically revised picture of the classic Wilson cycle The concept of ocean basins opening and closing is retained, but the process we envisage also involves thousands of kilometres of mainly dextral motion parallel with the margins of the opposing Laurentia and Gondwanaland continents, as well as complex and prolonged tectonic interaction across an often narrow ocean basin, rather than the single collision suggested by Wilson.
DS201911-2527
2019
Gilloly, T., Coltice, N., Wolf, C.An anticipation experiment for plate tectonics. Boundaries.Tectonics, in press availableMantleplate tectonics

Abstract: Although plate tectonics has pushed the frontiers of geosciences in the past 50 years, it has legitimate limitations and among them we focus on both the absence of dynamics in the theory, and the difficulty of reconstructing tectonics when data is sparse. In this manuscript, we propose an anticipation experiment, proposing a singular outlook on plate tectonics in the digital era. We hypothesize that mantle convection models producing self?consistently plate?like behavior will capture the essence of the self?organisation of plate boundaries. Such models exist today in a preliminary fashion and we use them here to build a database of mid?ocean ridge and trench configurations. To extract knowledge from it we develop a machine learning framework based on Generative Adversarial Networks (GANs) that learns the regularities of the self?organisation in order to fill gaps of observations when working on reconstructing a plate configuration. The user provides the distribution of known ridges and trenches, the location of the region where observations lack, and our digital architecture proposes a horizontal divergence map from which missing plate boundaries are extracted. Our framework is able to prolongate and interpolate plate boundaries within an unresolved region, but fails to retrieve a plate boundary that would be completely contained inside of it. The attempt we make is certainly too early because geodynamic models need improvement and a larger amount of geodynamic model outputs, as independent as possible, is required. However, this work suggests applying such an approach to expand the capabilities of plate tectonics is within reach.
DS201911-2531
2019
Hall, R.The subduction initiation stage of the Wilson cycle.N: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 415-437.Mantleplate tectonics

Abstract: In the Wilson cycle, there is a change from an opening to a closing ocean when subduction begins. Subduction initiation is commonly identified as a major problem in plate tectonics and is said to be nowhere observable, yet there are many young subduction zones at the west Pacific margins and in eastern Indonesia. Few studies have considered these examples. Banda subduction developed by the eastwards propagation of the Java trench into an oceanic embayment by tearing along a former ocean-continent boundary. The earlier subducted slab provided the driving force to drag down unsubducted oceanic lithosphere. Although this process may be common, it does not account for young subduction zones near Sulawesi at different stages of development. Subduction began there at the edges of ocean basins, not at former spreading centres or transforms. It initiated at a point where there were major differences in elevation between the ocean floor and the adjacent hot, weak and thickened arc/continental crust. The age of the ocean crust appears to be unimportant. A close relationship with extension is marked by the dramatic elevation of land, the exhumation of deep crust and the spectacular subsidence of basins, raising questions about the time required to move from no subduction to active subduction, and how initiation can be identified in the geological record.
DS201911-2532
2019
Heron, P.J.Mantle plumes and mantle dynamics in the Wilson Cycle.IN: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 87-103.Mantleplate tectonics

Abstract: This review discusses the thermal evolution of the mantle following large-scale tectonic activities such as continental collision and continental rifting. About 300 myr ago, continental material amalgamated through the large-scale subduction of oceanic seafloor, marking the termination of one or more oceanic basins (e.g. Wilson cycles) and the formation of the supercontinent Pangaea. The present day location of the continents is due to the rifting apart of Pangaea, with the dispersal of the supercontinent being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The discussion presented here investigates theories regarding the thermal evolution of the mantle (e.g. mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Rifting, orogenesis and mass eruptions from large igneous provinces change the landscape of the lithosphere, whereas processes related to the initiation and termination of oceanic subduction have a profound impact on deep mantle reservoirs and thermal upwelling through the modification of mantle flow. Upwelling and downwelling in mantle convection are dynamically linked and can influence processes from the crust to the core, placing the Wilson cycle and the evolution of oceans at the forefront of our dynamic Earth.
DS201911-2533
2019
Heron, P.J., Pysklywec, R.N., Stephenson, R.Exploring the theory of plate tectonics: the role of mantle lithosphere.N: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 137-155.Mantleplate tectonics

Abstract: This review of the role of the mantle lithosphere in plate tectonic processes collates a wide range of recent studies from seismology and numerical modelling. A continually growing catalogue of deep geophysical imaging has illuminated the mantle lithosphere and generated new interpretations of how the lithosphere evolves. We review current ideas about the role of continental mantle lithosphere in plate tectonic processes. Evidence seems to be growing that scarring in the continental mantle lithosphere is ubiquitous, which implies a reassessment of the widely held view that it is the inheritance of crustal structure only (rather than the lithosphere as a whole) that is most important in the conventional theory of plate tectonics (e.g. the Wilson cycle). Recent studies have interpreted mantle lithosphere heterogeneities to be pre-existing structures and, as such, linked to the Wilson cycle and inheritance. We consider the current fundamental questions in the role of the mantle lithosphere in causing tectonic deformation, reviewing recent results and highlighting the potential of the deep lithosphere in infiltrating every aspect of plate tectonics processes.
DS201911-2553
2019
Pastor-Galan, D., Nance, R.D., Murphy, J.B., Spencer, C.J.Supercontinents: myths, mysteries, and milestones.IN: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 39-64.Mantleplate tectonics

Abstract: There is an emerging consensus that Earth's landmasses amalgamate quasi-periodically into supercontinents, interpreted to be rigid super-plates essentially lacking tectonically active inner boundaries and showing little internal lithosphere-mantle interactions. The formation and disruption of supercontinents have been linked to changes in sea-level, biogeochemical cycles, global climate change, continental margin sedimentation, large igneous provinces, deep mantle circulation, outer core dynamics and Earth's magnetic field. If these hypotheses are correct, long-term mantle dynamics and much of the geological record, including the distribution of natural resources, may be largely controlled by these cycles. Despite their potential importance, however, many of these proposed links are, to date, permissive rather than proven. Sufficient data are not yet available to verify or fully understand the implications of the supercontinent cycle. Recent advances in many fields of geoscience provide clear directions for investigating the supercontinent cycle hypothesis and its corollaries but they need to be vigorously pursued if these far-reaching ideas are to be substantiated.
DS201911-2557
2019
Roman, A., Arndt, N.Differentiated Archean oceanic crust: its thermal structure, mechanical stability and a test of the sagduction hypothesis.Geochimica et Cosmochimica Acta, in press available. 13p.Mantleplate tectonics

Abstract: Many recent studies conclude that plate tectonics started about 3 billion years ago in the mid Archean. The transition from a pre-subduction regime to modern plate tectonics is reported to be marked by changes in trace element ratios or isotopic compositions that monitor the rate of growth of the continental crust, the appearance of eclogitic inclusions in diamonds, or an apparent change in the composition of the upper crust. Behind most of these arguments is the hypothesis that, early in Earth history when the mantle was hotter, subduction was intermittent or impossible. If so, a mechanism other than subduction must have created the granitoids that dominate Archean continental crust. One alternative, commonly referred to as sagduction, proposes that the base of thick oceanic crust founders and partially melts to generate granitic magma. Here we evaluate the sagduction process, starting by discussing two crucial concepts: (1) thick oceanic crust is internally differentiated, with hydrated basalt being restricted to the uppermost layers, (2) the generation of granitic magma requires that water and basalt is present in the lower part of the crust or is taken deep into the mantle. We present the results of numerical modelling that demonstrates that when intrusion is taken into account, the lower portion of the crust is well above dehydration temperatures and therefore essentially dry. We show that any deformation within thick, differentiated crust is restricted to the lowermost layers of dry, infertile mafic-ultramafic cumulates that lack the ingredients essential for the generation of granitic magma. Given the implausibility of the sagduction process, we suggest that subduction was the main mechanism that generated granitoid magmas, in the Archean as today.
DS201911-2561
2019
Sengor, A.M.C., Lom, N., Sagdic, N.G.Tectonic inheritance in the lithosphere.IN: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 105-136.Mantleplate tectonics
DS201911-2574
2019
Wilson, R.W., Huseman, G.A., Buiter, S.J.H., McCaffrey, K.J.W., Dore, A.G.Fifty years of the Wilson Cycle concept in plate tectonics: an overview.IN: Cycle Concepts in Plate Tectonics, editors Wilson and Houseman , Geological Society of London special publication 470, pp. 1-17. pdfMantleplate tectonics

Abstract: It is now more than 50 years since Tuzo Wilson published his paper asking ‘Did the Atlantic close and then re-open?’. This led to the ‘Wilson Cycle’ concept in which the repeated opening and closing of ocean basins along old orogenic belts is a key process in the assembly and breakup of supercontinents. This implied that the processes of rifting and mountain building somehow pre-conditioned and weakened the lithosphere in these regions, making them susceptible to strain localization during future deformation episodes. Here we provide a retrospective look at the development of the concept, how it has evolved over the past five decades, current thinking and future focus areas. The Wilson Cycle has proved enormously important to the theory and practice of geology and underlies much of what we know about the geological evolution of the Earth and its lithosphere. The concept will no doubt continue to be developed as we gain more understanding of the physical processes that control mantle convection and plate tectonics, and as more data become available from currently less accessible regions.
DS201912-2809
2019
O'Neill, C., Turner, S., Rushmer, T.The inception of plate tectonics: a record of failure.Philosophical Transactions A, Vol. 376, 28p. Pdf Mantleplate tectonics

Abstract: The development of plate tectonics from a pre-plate tectonics regime requires both the initiation of subduction and the development of nascent subduction zones into long-lived contiguous features. Subduction itself has been shown to be sensitive to system parameters such as thermal state and the specific rheology. While generally it has been shown that cold-interior high-Rayleigh-number convection (such as on the Earth today) favours plates and subduction, due to the ability of the interior stresses to couple with the lid, a given system may or may not have plate tectonics depending on its initial conditions. This has led to the idea that there is a strong history dependence to tectonic evolution—and the details of tectonic transitions, including whether they even occur, may depend on the early history of a planet. However, intrinsic convective stresses are not the only dynamic drivers of early planetary evolution. Early planetary geological evolution is dominated by volcanic processes and impacting. These have rarely been considered in thermal evolution models. Recent models exploring the details of plate tectonic initiation have explored the effect of strong thermal plumes or large impacts on surface tectonism, and found that these ‘primary drivers’ can initiate subduction, and, in some cases, over-ride the initial state of the planet. The corollary of this, of course, is that, in the absence of such ongoing drivers, existing or incipient subduction systems under early Earth conditions might fail. The only detailed planetary record we have of this development comes from Earth, and is restricted by the limited geological record of its earliest history. Many recent estimates have suggested an origin of plate tectonics at approximately 3.0?Ga, inferring a monotonically increasing transition from pre-plates, through subduction initiation, to continuous subduction and a modern plate tectonic regime around that time. However, both numerical modelling and the geological record itself suggest a strong nonlinearity in the dynamics of the transition, and it has been noted that the early history of Archaean greenstone belts and trondhjemite-tonalite-granodiorite record many instances of failed subduction. Here, we explore the history of subduction failure on the early Earth, and couple these with insights from numerical models of the geodynamic regime at the time.
DS202001-0029
2019
Mulyukova, E., Bercovici, D.The generation of plate tectonics from grains to global scales: a brief review.Tectonics, doi.org10.1029/ 2018tc005447Mantleplate tectonics

Abstract: The physics of rock deformation in the lithosphere governs the formation of tectonic plates, which are characterized by strong, broad plate interiors, separated by weak, localized plate boundaries. The size of mineral grains in particular controls rock strength and grain reduction can lead to shear localization and weakening in the strong ductile portion of the lithosphere. Grain damage theory describes the competition between grain growth and grain size reduction as a result of deformation, and the effect of grain size evolution on the rheology of lithospheric rocks. The self?weakening feedback predicted by grain damage theory can explain the formation of mylonites, typically found in deep ductile lithospheric shear zones, which are characteristic of localized tectonic plate boundaries. The amplification of damage is most effective when minerallic phases, like olivine and pyroxene, are well mixed on the grain scale. Grain mixing theory predicts two coexisting deformation states of unmixed materials undergoing slow strain rate, and well?mixed materials with large strain rate; this is in agreement with recent laboratory experiments, and is analogous to Earth's plate?like state. A new theory for the role of dislocations in grain size evolution resolves the rapid timescale of dynamic recrystallization. In particular, a toy model for the competition between normal grain growth and dynamic recrystallization predicts oscillations in grain size with periods comparable to earthquake cycles and postseismic recovery, thus connecting plate boundary formation processes to the human timescale.
DS202002-0209
2019
Molnar, P.Lower mantle dynamics perceived with 50 years of hindsight from plate tectonics.Geochemistry, Geophysics, Geosystems, Vol. 20, 12, pp. 5619-5649.( open access)Mantleplate tectonics

Abstract: Fifty years ago, plate tectonics united many aspects of the surface geology of the Earth, but little connection to the lower mantle was seen. Today, most view plate tectonics as the relative movements of cold, top, stiff boundary layers of a convecting system that reaches to the core?mantle boundary and with aspects of the deep structure not foreseen decades ago. Large provinces in the deepest ~1,000 km, in which P and S wave speeds are relatively low, not only seem to be chemically different from the neighboring mantle and from that at shallower depths, but their distribution also correlates with some aspects of the overlying surface geology, including the positions of major plumes rising from deep in the mantle and the positions of continents 100 to 200 Ma. These correlations imply a geodynamic connection between the lower mantle and the crust. Scaling laws derived from experiments in geophysical fluid mechanics suggest that the chemically distinct provinces may be relics from the earliest formation of the earth, but if not, they nevertheless have evolved slowly on the timescales of geologic eras. A concurrent emerging view of the lower mantle, however, also places increased emphasis on a boundary at ~1,000 (±100) km depth, and this boundary might define a barrier to cold sinking slabs of lithosphere. A few isolated plumes of hot material that are also chemically different from most of the mantle penetrate this interface at 1,000 km, but it seems possible that this boundary may separate mantle convection into two separate layers, as was thought 50 years ago in the early plate tectonics era, when the 660?km discontinuity was thought to separate two independently convecting layers. If convection is better described as layered than involving the entire mantle as one layer, the old view of the driving mechanism of plate tectonics—that high lithostatic pressures at ridges push plates apart, cold, dense sinking slabs pull them down and drag over the asthenosphere resists plate motions—seems to be revalidated, and the relative motions of plates do not require a role for the lower mantle.
DS202004-0539
2020
Tetley, M.G., Li, Z-X., Matthews, K.J., Williams, S.E.Decoding Earth's plate tectonic history using sparse geochemical data. RodiniaGeoscience Frontiers, in press available 12p. PdfMantleplate tectonics

Abstract: Accurately mapping plate boundary types and locations through time is essential for understanding the evolution of the plate-mantle system and the exchange of material between the solid Earth and surface environments. However, the complexity of the Earth system and the cryptic nature of the geological record make it difficult to discriminate tectonic environments through deep time. Here we present a new method for identifying tectonic paleo-environments on Earth through a data mining approach using global geochemical data. We first fingerprint a variety of present-day tectonic environments utilising up to 136 geochemical data attributes in any available combination. A total of 38301 geochemical analyses from basalts aged from 5-0 Ma together with a well-established plate reconstruction model are used to construct a suite of discriminatory models for the first order tectonic environments of subduction and mid-ocean ridge as distinct from intraplate hotspot oceanic environments, identifying 41, 35, and 39 key discriminatory geochemical attributes, respectively. After training and validation, our model is applied to a global geochemical database of 1547 basalt samples of unknown tectonic origin aged between 1000-410 Ma, a relatively ill-constrained period of Earth's evolution following the breakup of the Rodinia supercontinent, producing 56 unique global tectonic environment predictions throughout the Neoproterozoic and Early Paleozoic. Predictions are used to discriminate between three alternative published Rodinia configuration models, identifying the model demonstrating the closest spatio-temporal consistency with the basalt record, and emphasizing the importance of integrating geochemical data into plate reconstructions. Our approach offers an extensible framework for constructing full-plate, deep-time reconstructions capable of assimilating a broad range of geochemical and geological observations, enabling next generation Earth system models.
DS202005-0737
2019
Hoffman, P.F.Big Time: Proterozoic Eon.Annual Review of Earth and Planetary Sciences, Vol. 47, pp. 1-17. pdfMantleplate tectonics

Abstract: The Proterozoic Eon was once regarded as the neglected middle half of Earth history. The name refers to early animals, but they did not appear until the eon (2.5-0.54 Ga) was nearly over. Eukaryotic cells and sexual reproduction evolved much earlier in the eon, as did chloroplasts. Molecular dioxygen, the presence of which altered the geochemical behavior of nearly every element essential to life, rose from negligible to near-modern levels, and then plummeted before rising fitfully again. Plate tectonics took on a modern form, and two supercontinents, Nuna and Rodinia, successively congregated and later dispersed. Climate regulatory failures, i.e., Snowball Earth, appear to be a uniquely Proterozoic phenomenon, having occurred twice in rapid succession near the end of the eon (from 717 to 660 Ma and from 650 to 635 Ma) and arguably once near its beginning (ca. 2.43 Ga). Dynamic sea glaciers covered Snowball Earth oceans from pole to pole, and equatorial sublimation drove slow-moving ice sheets on land. Ultimately, the gradual accumulation of CO2 triggered rapid deglaciation and transient greenhouse aftermaths. Physically based and geologically tested, Neoproterozoic Snowball Earth appears to have molecular legacies in ancient bitumens and modern organisms. This is the story of my love affair with an eon that is now a little less neglected.
DS202007-1168
2020
Palin, R.M., Santosh, M., Cao, W., Li, S-S., Hernandez-Uribe, D.Secular change and the onset of plate tectonics on Earth.Earth Science Reviews, in press available 41p. PdfMantleplate tectonics

Abstract: The Earth as a planetary system has experienced significant change since its formation c. 4.54 Gyr ago. Some of these changes have been gradual, such as secular cooling of the mantle, and some have been abrupt, such as the rapid increase in free oxygen in the atmosphere at the Archean-Proterozoic transition. Many of these changes have directly affected tectonic processes on Earth and are manifest by temporal trends within the sedimentary, igneous, and metamorphic rock record. Indeed, the timing of global onset of mobile-lid (subduction-driven) plate tectonics on our planet remains one of the fundamental points of debate within the geosciences today, and constraining the age and cause of this transition has profound implications for understanding our own planet's long-term evolution, and that for other rocky bodies in our solar system. Interpretations based on various sources of evidence have led different authors to propose a very wide range of ages for the onset of subduction-driven tectonics, which span almost all of Earth history from the Hadean to the Neoproterozoic, with this uncertainty stemming from the varying reliability of different proxies. Here, we review evidence for paleo-subduction preserved within the geological record, with a focus on metamorphic rocks and the geodynamic information that can be derived from them. First, we describe the different types of tectonic/geodynamic regimes that may occur on Earth or any other silicate body, and then review different models for the thermal evolution of the Earth and the geodynamic conditions necessary for plate tectonics to stabilize on a rocky planet. The community's current understanding of the petrology and structure of Archean and Proterozoic oceanic and continental crust is then discussed in comparison with modern-day equivalents, including how and why they differ. We then summarize evidence for the operation of subduction through time, including petrological (metamorphic), tectonic, and geochemical/isotopic data, and the results of petrological and geodynamical modeling. The styles of metamorphism in the Archean are then examined and we discuss how the secular distribution of metamorphic rock types can inform the type of geodynamic regime that operated at any point in time. In conclusion, we argue that most independent observations from the geological record and results of lithospheric-scale geodynamic modeling support a global-scale initiation of plate tectonics no later than c. 3 Ga, just preceding the Archean-Proterozoic transition. Evidence for subduction in Early Archean terranes is likely accounted for by localized occurrences of plume-induced subduction initiation, although these did not develop into a stable, globally connected network of plate boundaries until later in Earth history. Finally, we provide a discussion of major unresolved questions related to this review's theme and provide suggested directions for future research.
DS202009-1631
2020
Hyung, E., Jacobsen, S.The 142Nd/144 Nd variations in mantle derived rocks provide constraints on the stirring rate of the mantle from the Hadean to the present.Proceedings of the National Academy of Sciences, Voll. 176, no. 26, 14738-44. pdfMantleplate tectonics

Abstract: Early silicate differentiation events for the terrestrial planets can be traced with the short-lived 146Sm-142Nd system (?100-My half-life). Resulting early Earth-produced 142Nd/144Nd variations are an excellent tracer of the rate of mantle mixing and thus a potential tracer of plate tectonics through time. Evidence for early silicate differentiation in the Hadean (4.6 to 4.0 Ga) has been provided by 142Nd/144Nd measurements of rocks that show both higher and lower (±20 ppm) values than the present-day mantle, demonstrating major silicate Earth differentiation within the first 100 My of solar system formation. We have obtained an external 2? uncertainty at 1.7 ppm for 142Nd/144Nd measurements to constrain its homogeneity/heterogeneity in the mantle for the last 2 Ga. We report that most modern-day mid-ocean ridge basalt and ocean island basalt samples as well as continental crustal rocks going back to 2 Ga are within 1.7 ppm of the average Earth 142Nd/144Nd value. Considering mafic and ultramafic compositions, we use a mantle-mixing model to show that this trend is consistent with a mantle stirring time of about 400 My since the early Hadean. Such a fast mantle stirring rate supports the notion that Earth’s thermal and chemical evolution is likely to have been largely regulated by plate tectonics for most of its history. Some young rocks have 142Nd/144Nd signatures marginally resolved (?3 ppm), suggesting that the entire mantle is not equally well homogenized and that some silicate mantle signatures from an early differentiated mantle (>4.1 Ga ago) are preserved in the modern mantle.
DS202009-1640
2020
Lenardic, A., Seales, J., Weller, M.B.Convective and tectonic plate velocities in a mixed heating mantle.Researchgate, July 29p. Pdf doi:101002 /essoar.10503603.1Mantleplate tectonics

Abstract: Mantle convection and, by association, plate tectonics is driven by the transport of heat from a planetary interior. This heat may come from the internal energy of the mantle or may come from the core beneath and in general there will be contributions from both sources. Past investigations of such mixed-mode heating have revealed unusual behavior that confounds our intuition based on boundary layer theory applied to end-member cases. In particular, the addition of internal heat to a bottom-heated system causes a decrease in convective velocity despite an increase in surface heat flow. We investigate this behavior using a suite of numerical experiments and develop a scaling for velocity in the mixed-heating case. We identify a significant planform transition as internal heating increases from sheet-like to plume-like downwellings that impacts both heat flux and convective velocities. More significantly, we demonstrate that increased internal heating leads not only to a decrease in internal velocities but also a decrease in the velocity of the upper thermal boundary layer (a model analog of the Earth's lithosphere). This behavior is connected to boundary layer interactions and is independent of any particular rheological assumptions. In simulations with a temperature-dependent viscosity and a finite yield stress, increased internal heating does not cause an absolute decrease in surface velocity but does cause a decrease in surface velocity relative to the purely bottom or internally heated cases as well as a transition to rigid-lid behavior at high heating rates. The differences between a mixed system and end-member cases have implications for understanding the connection between plate tectonics and mantle convection and for planetary thermal history modeling.
DS202012-2237
2020
Palin, R.M., Santosh, M.Plate tectonics: what, where, why, and when?Gondwana Research, in proof available, 105p. Pdf 10.1016/j.gr.2020.11.001Globalplate tectonics
DS202012-2255
2020
Windley, B.F., Kusky, T., Polat, A.Onset of plate tectonics by the Eoarchean. ( accretionary and collisional)Precambrian Research, in press available, 43p. PdfMantleplate tectonics

Abstract: One of the most contentious areas of Earth Science today is when, or whether or not modern-style plate tectonics was in operation in the Archean Eon. In this review we present evidence that the onset of plate tectonics was not at 3.2 Ga, as popularly conceived, but was in operation during the Eoarchean by at least ca. 4.0 Ga. Following a review of the main Eoarchean supracrustal belts of the world, constrained by relevant geochemical/isotopic data, we present evidence that suggests that from at least ca. 4.0 Ga Earth produced considerable juvenile mafic crust and consequent island arcs by Accretionary Cycle Plate Tectonics. From ~3.2 Ga there was a gradual transition in geodynamics to more abundant active continental margin magmatism in the form of voluminous TTGs and sanukitoids. From 3.2 Ga to 2.5 Ga juvenile oceanic crust and arcs continued to form, accompanied by more active continental margin magmatism until ~2.7-2.5 Ga, by which time there were sufficient crustal rocks to amalgamate into incipient large continents, the fragmentation of which started the first complete classical Wilson Cycle Plate Tectonics of breaking apart and re-assembling large continental masses. In other words, there were two types of plate tectonics in operation in the early Earth, Accretionary Cycle Plate Tectonics and Wilson Cycle Plate Tectonics, but Wilson Cycle type plate interactions only became more common after contiguous continental landmass became voluminous and extensive enough around 2.7-2.5 Ga. Failure to realize this dual mechanism of continental growth may lead to erroneous ideas such as "plate tectonics started at 3.2 Ga", or "mantle plumes generated early Archean magmatic rocks." We present new geochemical data that together with lithological and structural relationships, negate the various plume-type speculations including stagnant lids, heat pipes, and mushy-lid tectonics. It is interesting to consider that the way Earth’s crust developed in the first Gigayear of the geological record continued later, albeit in more advanced forms, into the Phanerozoic, where we can still recognize Accretionary Cycle Plate Tectonics and orogens still with short boundaries in examples including the Altaids of Central Asia, the Arabian-Nubian Shield, the Japanese Islands, and in incipient form in Indonesia, as well as Wilson Cycle Plate Tectonics that leads inexorably to continental collisions as in the Alpine-Himalayan orogen with its long plate boundaries. We recommend this holistic view of crustal growth and the evolution of continents that leads to a robust, viable, and testable model of Earth evolution.
DS202102-0235
2021
Windley, B.F., Kusky, T., Polat, A.Onset of plate tectonics by the Eoarchean.Precambrian Research, doi.org/1-.1016/ j.precamres.2020 .105980, 43p. PdfMantleplate tectonics

Abstract: One of the most contentious areas of Earth Science today is when, or whether or not modern-style plate tectonics was in operation in the Archean Eon. In this review we present evidence that the onset of plate tectonics was not at 3.2 Ga, as popularly conceived, but was in operation during the Eoarchean by at least ca. 4.0 Ga. Following a review of the main Eoarchean supracrustal belts of the world, constrained by relevant geochemical/isotopic data, we present evidence that suggests that from at least ca. 4.0 Ga Earth produced considerable juvenile mafic crust and consequent island arcs by Accretionary Cycle Plate Tectonics. From ~3.2 Ga there was a gradual transition in geodynamics to more abundant active continental margin magmatism in the form of voluminous TTGs and sanukitoids. From 3.2 Ga to 2.5 Ga juvenile oceanic crust and arcs continued to form, accompanied by more active continental margin magmatism until ~2.7-2.5 Ga, by which time there were sufficient crustal rocks to amalgamate into incipient large continents, the fragmentation of which started the first complete classical Wilson Cycle Plate Tectonics of breaking apart and re-assembling large continental masses. In other words, there were two types of plate tectonics in operation in the early Earth, Accretionary Cycle Plate Tectonics and Wilson Cycle Plate Tectonics, but Wilson Cycle type plate interactions only became more common after contiguous continental landmass became voluminous and extensive enough around 2.7-2.5 Ga. Failure to realize this dual mechanism of continental growth may lead to erroneous ideas such as "plate tectonics started at 3.2 Ga", or "mantle plumes generated early Archean magmatic rocks." We present new geochemical data that together with lithological and structural relationships, negate the various plume-type speculations including stagnant lids, heat pipes, and mushy-lid tectonics. It is interesting to consider that the way Earth’s crust developed in the first Gigayear of the geological record continued later, albeit in more advanced forms, into the Phanerozoic, where we can still recognize Accretionary Cycle Plate Tectonics and orogens still with short boundaries in examples including the Altaids of Central Asia, the Arabian-Nubian Shield, the Japanese Islands, and in incipient form in Indonesia, as well as Wilson Cycle Plate Tectonics that leads inexorably to continental collisions as in the Alpine-Himalayan orogen with its long plate boundaries. We recommend this holistic view of crustal growth and the evolution of continents that leads to a robust, viable, and testable model of Earth evolution.
DS202103-0394
2021
Merdith, A.S., Williams, S.E., Collins, A.S., Tetley, M.G., Mulder, J.A., Blades, M.L., Young, A., Armistead, S.E., Cannon, J., Zahirovic, S., Muller, R.D.Extending full plate tectonic models into deep time: linking the Neoproterozoic and the Phanerozoic.Earth Science Reviews, Vol. 214, 44p. PdfMantleplate tectonics

Abstract: Recent progress in plate tectonic reconstructions has seen models move beyond the classical idea of continental drift by attempting to reconstruct the full evolving configuration of tectonic plates and plate boundaries. A particular problem for the Neoproterozoic and Cambrian is that many existing interpretations of geological and palaeomagnetic data have remained disconnected from younger, better-constrained periods in Earth history. An important test of deep time reconstructions is therefore to demonstrate the continuous kinematic viability of tectonic motions across multiple supercontinent cycles. We present, for the first time, a continuous full-plate model spanning 1 Ga to the present-day, that includes a revised and improved model for the Neoproterozoic-Cambrian (1000-520 Ma) that connects with models of the Phanerozoic, thereby opening up pre-Gondwana times for quantitative analysis and further regional refinements. In this contribution, we first summarise methodological approaches to full-plate modelling and review the existing full-plate models in order to select appropriate models that produce a single continuous model. Our model is presented in a palaeomagnetic reference frame, with a newly-derived apparent polar wander path for Gondwana from 540 to 320 Ma, and a global apparent polar wander path from 320 to 0 Ma. We stress, though while we have used palaeomagnetic data when available, the model is also geologically constrained, based on preserved data from past-plate boundaries. This study is intended as a first step in the direction of a detailed and self-consistent tectonic reconstruction for the last billion years of Earth history, and our model files are released to facilitate community development.
DS202104-0612
2020
Varga, P., Fodor, C.About the energy and age of the plate tectonics.Terra Nova, 10.1111/ter.12518 7p. PdfMantleplate tectonics

Abstract: Recently, a number of research findings have come to light about the age of plate tectonics, and energies are needed to operate it. The aim of present study is to investigate whether the energy of plate tectonics process was different during the Phanerozoic (Pz) and in earlier eons, and if there is such a discrepancy, whether it can be justified by changes in the processes that able to move the plates. The study will track temporal changes in important components of plate tectonics such as length of mid?ocean ridges, subduction zones and relative oceanic crust coverage during Phanerozoic. Next, it will be examined how the knowledge gained in this way can be reconciled with the results of studies of previous eons. It was found that the temporal variation in kinetic energy of axial rotation due to changes in length of day (LOD) can be assumed as a determining energy which acts on the tectonic plates as in the Phanerozoic as earlier in Archean (Arch) and Proterozoic (Ptz).
DS202106-0951
2021
Le Pichon, X., Jellinek, M., Lenardic, A., Sengor, A.M.C., Imren, C.Pangea migration.Tectonics, e2020TC006585 42p. PdfMantleplate tectonics

Abstract: We confirm the proposition of Le Pichon et al. (2019) that Pangea was ringed by a hemispheric subduction girdle from its formation 400 Ma to its dispersal 100 Ma. We quantify the northward migration, that we attribute to True Polar Wander (TPW), of its axis of symmetry, between 400 Ma and 150 Ma, from southern latitudes to the equatorial zone. The spatial stabilizing within the equatorial zone of the axis of symmetry in a fixed position with respect to lower mantle, was marked by alternating CW and CCW oscillations between 250 Ma and 100 Ma that we relate to tectonic events. A subduction girdle is predicted to set up lateral temperature gradients from relatively warm sub-Pangean mantle to cooler sub-oceanic mantle. Over time, this effect acts to destabilize the Pangea landmass and its associated subduction girdle. Quantitatively, a scaling theory for the stability of the subduction girdle against mantle overturn constrains the maximum magnitude of sub-Pangean warming before breakup to be order 100 oC, consistent with constraints on Pacific-Atlantic oceanic crustal thickness differences. Our predictions are in line with recent analyses of Jurassic-Cretaceous climate change and with existing models for potential driving forces for a TPW oscillation of Pangea across the equator. The timing and intensity of predicted sub-Pangean warming potentially contributed to the enigmatically large Siberian Traps and CAMP flood basalts at 250 Ma and 201 Ma, respectively.
DS202108-1304
2021
Peace, A.L.Beyond ' crumple zones': recent advances, application and future directions in deformable plate tectonic modeling.Geological Magazine, doi:10.1017/S0016756821000534 7p.Mantleplate tectonics

Abstract: The recent proliferation of deformable plate tectonic modelling techniques has provided a new direction in the study of plate tectonics with substantial implications for our understanding of plate deformation and past kinematics. Such models account for intraplate deformation, yet are highly variable in their inputs, capabilities and applications. The aim of this commentary is to review recent contributions to this topic, and to consider future directions and major omissions. Through this review it is apparent that the current published deformable models can be subdivided into those that as an input either: (1) solely use plate motions to drive deformation, or (2) require stretching or beta factor. Deformable models are resolving some outstanding issues with plate reconstructions, but major simplifications and modelling assumptions remain. Primarily, obtaining model constraints on the spatio-temporal evolution of deformation is an outstanding problem. Deformable plate models likely work best when the kinematics of smaller plates are included. However, questions remain regarding how to define such blocks, and their kinematic histories, whilst some work suggests that inclusion of such entities is negated through quantitative restorations.
DS202109-1481
2021
Meredith, A.S., Williams, S.E., Collins, A.S., Tetley, M.G., Mulder, J.A., Blades, M.L., Young, A., Armistead, S.E., Cannon, J., Zahirovic, S., Muller, R.D.Extending full plate tectonic models into deep time: linking the Neoproterozoic and the Phanerozoic.Earth Science Reviews , Vol. 214, 103477, 44p. PdfMantleplate tectonics, Rodinia, Gondwana

Abstract: Recent progress in plate tectonic reconstructions has seen models move beyond the classical idea of continental drift by attempting to reconstruct the full evolving configuration of tectonic plates and plate boundaries. A particular problem for the Neoproterozoic and Cambrian is that many existing interpretations of geological and palaeomagnetic data have remained disconnected from younger, better-constrained periods in Earth history. An important test of deep time reconstructions is therefore to demonstrate the continuous kinematic viability of tectonic motions across multiple supercontinent cycles. We present, for the first time, a continuous full-plate model spanning 1 Ga to the present-day, that includes a revised and improved model for the Neoproterozoic-Cambrian (1000-520 Ma) that connects with models of the Phanerozoic, thereby opening up pre-Gondwana times for quantitative analysis and further regional refinements. In this contribution, we first summarise methodological approaches to full-plate modelling and review the existing full-plate models in order to select appropriate models that produce a single continuous model. Our model is presented in a palaeomagnetic reference frame, with a newly-derived apparent polar wander path for Gondwana from 540 to 320 Ma, and a global apparent polar wander path from 320 to 0 Ma. We stress, though while we have used palaeomagnetic data when available, the model is also geologically constrained, based on preserved data from past-plate boundaries. This study is intended as a first step in the direction of a detailed and self-consistent tectonic reconstruction for the last billion years of Earth history, and our model files are released to facilitate community development.
DS202203-0352
2021
Humphreys-Williams, E.R., Zahirovic, S.Carbonatites and global tectonics. 609 Occurrences and 387 known ageElements, Vol. 17, pp. 339-344.Globalplate tectonics

Abstract: Carbonatites have formed for at least the past three billion years. But over the past 700 My the incidence of carbonatites have significantly increased. We compile an updated list of 609 carbonatite occurrences and plot 387 of known age on plate tectonic reconstructions. Plate reconstructions from Devonian to present show that 75% of carbonatites are emplaced within 600 km of craton edges. Carbonatites are also associated with large igneous provinces, orogenies, and rift zones, suggesting that carbonatite magmatism is restricted to discrete geotectonic environments that can overlap in space and time. Temporal constraints indicate carbonatites and related magmas may form an ephemeral but significant flux of carbon between the mantle and atmosphere.
DS202205-0715
2022
Seals, J., Lenardic, A., Garrido, J.Plate tectonics, mixed heating convection and the divergence.Researchgate preprint, 12p. PdfMantleplate tectonics

Abstract: Petrological data indicate that upper mantle and mantle plume temperatures diverged 2.5 billion years ago. This has been interpreted as plate tectonics initiating at 2.5 Ga with Earth operating as a single plate planet before then. We take an Occam’s razor view that the continuous operation of plate tectonics can explain the divergence. We validate this hypothesis by comparing petrological data to results from mixed heating mantle convection models in a plate tectonic mode of mantle cooling. The comparison shows that the data are consistent with plate tectonics operating over geologic history.

 
 

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