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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Dykes
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
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.
Dykes refer to sheet like intrusions that never erupted. When they are near horizontal they are referred to as sills. Dykes and sills are relevant to diamonds when they consist of kimberlite, and although volumetrically small and likely requiring underground mining, have the advantage that their diamond grade has not been diluted by country rock infilling as happens when a kimberlite erupts and forms a pipe.
Age and geochemical characteristics of a mafic dyke swarm in the Archean vestfold block Antarctica- inferences about Proterozoic dyke emplacement inGondwana
Journal of Petrology, Vol. 27, No. 4, August pp. 853-886
Fahrig, W.F., Christie, K.W., Chown, E.H., Janes, D., Machado, N.
The tectonic significance of some basic dyke swarms in the Canadian Superior province with special reference to The geochemistry and paleomagnetism of th
Canadian Journal of Earth Sciences, Vol. 23, No. 2, February pp. 238-253
The tectonic significance of some basic dike swarms in the Canadian Superior Province with special reference to geochemistry and paleomagnetism of Mistassini swarm
Canadian Journal of Earth Sciences, Vol. 23, pp. 238-53.
Trace element and neodymium isotopic variations in Early Proterozoic dyke swarms emplaced in the vicinity of the Kapuskasing structural zone. enriched mantleAFC.
Canadian Journal of Earth Sciences, Vol. 28, pp. 26-36.
Ontario
Assimilation fractional crystallization, Tectonics, rifting, dike swarms
Intrusion of horizontal dikes -tectonic significance of middle Proterozoic diabase sheets Wide spread in the Upper crust of the southwestern United States
Journal of Geophysical Research, Vol. 96, No. B7, July 10, pp. 12, 461-12, 478
Argon isotope and halogen chemistry of phlogopite from South Africankimberlites: a combined step-heating, laser probe, electron microprobe and TEMstudy
Enriched and depleted components in early Proterozoic mantle: evidence from neodymium and Sr isotopic study of layered intrusions and mafic dykes eastern shield
Eos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.338
Lamproites and diamond potential of the Churchill Province
The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) , Annual Meeting Abstracts approximately 10 lines, Vol. 86, No. 968, March ABSTRACT p. 71.
samarium-neodymium (Sm-Nd) mineral isochron ages of Late Proterozoic dyke swarms in Australia:evidence for two distinctive events of mafic magmatism and crustal extension.
uranium-lead (U-Pb) (U-Pb) ages of Proterozoic dyke swarms, Lac de Gras area, Northwest Territories: evidence for progressive break up of an Archean supercontinent.
Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.
Paleomagnetism, U Pb geochronology and geochemistry of Lac Esprit and other dyke swarms, James Bay area, Quebec: implications for Paleoproterozoic deformation
Canadian Journal of Earth Sciences, Vol. 44, 5, pp. 643-664.
Youbi, N., Kouyate, D., Soderlund, U., Ernst, R.E., Soulaimani, A., Hafid, A., Ikenne, M., El Bahat, A., Betrand, H., Chaham, K.R., Ben Abbou, M., Mortaji, A., El Ghorfi, M., Zouhair, M., El Janati, M.
The 1750 Ma magmatic event of the West African Craton ( Anti-Atlas) Morocco.
Abstract: Field setting, petrography, geochemistry and available radiometric ages of Proterozoic mafic dykes from the northern Bastar craton have helped to identify four sets of mafic dykes; two Paleoproterozoic [viz. NW-SE North Bastar dykes (NBD) and ENE-WSW Dongargarh-Chhura dykes (DCD)] and two Mesoproterozoic [viz. 1.42 Ga ENE-WSW Bandalimal dykes (BDD) and 1.44 Ga N-S Lakhna dykes (LKD)]. Their petrographic and geochemical characteristics are very distinct and suggest their derivation from different mantle melts. Chemistry of all the four sets suggests different petrogenetic histories and samples of each distinct set are co-genetic nature. The NBD, the DCD and the BDD samples are sub-alkaline tholeiitic in nature, whereas the LKD samples show alkaline nature. Very distinct REE patterns are observed for all the four sets again suggesting their different petrogenetic histories. Geochemical comparison between the studied samples and mafic dyke samples of southern and central parts of the Bastar craton suggests very different picture for the northern Bastar craton. Only one set of northern Bastar dykes, i.e. the NBD, matches with BD1 dykes; no other dyke sets match with any of the dyke swarms identified in southern and central Bastar craton. Geochemically it is not straightforward to confirm crustal contamination, however, on the other hand, possibility of crustal contamination cannot be ruled out completely. A petrogenetic model based on trace element data suggests that all the four sets are derived from different mantle melts. The NBD and the DCD are probably generated within spinel stability field, whereas the BDD and the LKD may be derived from melts generated within garnet stability field. Available geological and geochemical data support the emplacement of studied dykes in a stable continental rift tectonic setting, however earlier intrusions have chemistry similar to N-MORB. The available geological, geochemical and geochronological data on the four indentified sets of mafic dykes from the northern Bastar craton indicate their relation to the assembly and break-up of Columbia supercontinent.
Geochemistry, Geophysics, Geosystems: G3, Vol. 16, in press available
Africa, East Africa
Dyke swarms
Abstract: The role of dike intrusion in driving continental breakup is fundamental to our understanding of plate tectonics. Buck (2004) showed that the breakup of thick continental lithosphere requires more than far-field tectonic forces, illustrating the important role of dike opening in driving extension during the earliest stages of rifting. Upper crustal diking in rift environments is often depicted to occur through long (up to 80 km), sub-parallel swarms intruding along the full length of rift basins. These assertions are supported by recent dike-driven rifting events in Iceland and Ethiopia (Wright et al., 2012), and inform numerical modelling studies addressing the mechanical effects of dike intrusion to rift processes (e.g., Buck et al., 2005).
Our current view of dike networks, however, may be biased to evolved (>20 Ma), oceanic (e.g., Krafla) or nascent (e.g., Dabbahu-Manda-Hararo) spreading centers. This is largely because magmatic rifting occurs in these regions with a high enough frequency that it can be persistently captured using modern-day monitoring techniques (e.g., InSAR and seismicity). Dike networks throughout other sectors of the East African Rift may instead exhibit greater complexity, particularly in early-stage rifts (<10 Ma) undergoing infrequent diking episodes (Calais et al., 2008). By unravelling the contributions of dikes in these basins we can further refine our understanding of the role of magmatism during continental rift initiation.
Current geophysical techniques (e.g., seismic reflection) lack the capacity to resolve thin, sub-vertical structures in the sub-surface, and thus reconstructing the geometries of cooled, upper crustal dike swarms poses a significant challenge. Recent structural and volcanological studies in both active and eroded monogenetic volcanic fields have illustrated the utility of volcanic vent alignments and cone morphometrics for inferring the distributions and orientations of upper crustal dikes (Kiyosugi et al., 2012; Le Corvec et al., 2013; Keir et al., 2015). The East African Rift exhibits numerous monogenetic cone fields that may help us understand the distribution and geometry of shallow dike-feeders emplaced in the last few million years (Korme et al., 1997; Mazzarini et al., 2013). Building on these studies and methods, we performed a comparative analysis of upper crustal diking in various rift basins throughout East Africa, based on the distributions, alignments and morphologies of monogenetic cones (Muirhead et al., 2015).
Abstract: The Mesoproterozoic Gardar Province in South Greenland developed in a continental rift-related environment. Several alkaline intrusions and associated dyke swarms were emplaced in Archaean and Ketilidian basement rocks during two main magmatic periods at 1300-1250 Ma and 1180-1140 Ma. The present investigation focuses on mafic dykes from the early magmatic period (‘Older Gardar’) and the identification of their possible mantle sources. The rocks are typically fine- to coarse-grained dolerites, transitional between tholeiitic and alkaline compositions with a general predominance of Na over K. They crystallized from relatively evolved, mantle-derived melts and commonly show minor degrees of crustal contamination. Selective enrichment of the large ion lithophile elements Cs, Ba and K and the light rare-earth elements when compared to high field-strength elements indicate significant involvement of a sub-continental lithospheric mantle (SCLM) component in the generation of the magmas. This component was affected by fluid-dominated supra-subduction zone metasomatism, possibly related to the Ketilidian orogeny ~500 Ma years prior to the onset of Gardar magmatism. Melt generation in the SCLM is further documented by the inferential presence of amphibole in the source region, negative calculated ?Nd(i) values (?0.47 to ?4.40) and slightly elevated 87Sr/86Sr(i) (0.702987 to 0.706472) ratios when compared to bulk silicate earth as well as relatively flat heavy rare-earth element (HREE) patterns ((Gd/Yb)N = 1.4-1.9) indicating melt generation above the garnet stability field. The dyke rocks investigated show strong geochemical and geochronological similarities to pene-contemporaneous mafic dyke swarms in North America and Central Scandinavia and a petrogenetic link is hypothesized. Considering recent plate reconstructions, it is further suggested that magmatism was formed behind a long-lived orogenic belt in response to back-arc basin formation in the time interval between 1290-1235 Ma.
Abstract: The widespread mafic to intermediate dykes in the northern Sulu orogen provide important constrains on mantle source characteristics and geodynamic setting. Here we present LA-ICPMS zircon U-Pb ages which indicate that the dykes were emplaced during Early Cretaceous (~ 113-108 Ma). The rocks show SiO2 in the range of 46.2 to 59.5 wt.% and alkalic and shoshonitic affinity with high concentrations of MgO (up to 7.6 wt.%), Cr (up to 422 ppm) and Ni (up to 307 ppm). They are enriched in light rare earth elements LREE (La, Ce, Pr, Nd, Sm and Eu) and large ion lithophile elements (LILE, Rb, Sr, Ba, U and Th) and show strong depletion in high field strength elements (HFSE, Nb, Ta, Ti and P). The dykes possess uniformly high (87Sr/86Sr)i (0.70824-0.70983), low ?Nd(t) (? 14.0 to ? 17.4) and (206Pb/204Pb)i (16.66-17.02) and negative ?Hf(t) (? 23.5 to ? 13.7). Our results suggest that the source magma did not undergo any significant crustal contamination during ascent. The systematic variation trends between MgO and major and trace elements suggest fractionation of olivine and clinopyroxene. The highly enriched mantle source for these rocks might have involved melts derived from the subducted lower crust of Yangtze Craton that metasomatized the ancient lithospheric mantle of the North China Craton.
Abstract: The North China Craton is a classic case for the destruction of an ancient craton, in that it records the loss of more than 100 km of ancient refractory lithospheric mantle during the late Mesozoic and early Cenozoic. However, the mechanisms for this lithospheric thinning remain controversial in large part due to the lack of any systematic investigations of the Mesozoic asthenospheric mantle via its derived mafic rocks, which are key to understand the thinning processes. In this paper, we present detailed zircon U-Pb geochronology, elemental geochemistry, and Sr-Nd-Hf isotopic data for lamprophyres and diabase-porphyries of the Jiaodong Peninsula, in the eastern North China Craton in order to place constraints on models for lithospheric thinning. Our results show that the lamprophyres and diabase-porphyries are derived from the convective asthenospheric mantle via different degrees of partial melting, and that this mantle source was previously modified by carbonatitic liquids. Zircon LA-ICP-MS U-Pb dating suggests an emplacement age for these rocks of 123-121 Ma, the earliest evidence for asthenospherically-derived melts in the Jiaodong Peninsula so far. This emplacement age indicates that the thickness of the lithosphere in the Jiaodong Peninsula was relatively thin at that time. Co-occurrence of the asthenospheric and lithospheric mantle-derived mafic rocks as well as high-Mg adakites record a rapid transition from lithospheric to asthenospheric mantle sources, indicating that the lithosphere beneath the Jiaodong Peninsula was rapidly detached just prior to ca. 120 Ma. Lithospheric thinning of the North China Craton may have been initiated from the Jiaodong Peninsula and Bohai Sea and then propagated towards the interior of the craton.
Abstract: We constructed a thermomechanical model to examine the changes in rheology caused by the periodic intrusion of basaltic dykes in a two-layered continental crust. Dyke intrusion can locally change the mineralogical composition of the crust in space and time as a result of temperature-induced metamorphism. In our models we paid particular attention to determine how different mineral assemblages and reaction kinetics during metamorphism impact on the thermomechanical behavior of the crust, in terms of differential stress values. We investigated several lithologies characteristic for intracontinental crust: (1) a quartz-feldspathic crust (QF), (2) a crust with a mineralogical assemblage resembling the average chemical composition occurring in literature (CC), and (3) a micaschist crust (MS). Our model shows that temperature profiles are weakly influenced by metamorphism, with negligible variations in the T-t paths. The results indicate that intrusion-induced changes in the crustal rheology are strongly dependent on mineralogical assemblage variation. The strength of a dyke aureole in the upper crust increases during dyke emplacement, which may cause migration of later dykes and influence the dyke spacing. In contrast, in the lower crust the strength of a dyke aureole decreases during dyke emplacement. Fast kinetics results in a ductile lower crust in proximity of the dykes, whereas slower kinetics leads to the formation of partial melts and subsequent switch from ductile to brittle behavior. Lithology exerts a dominant role on the quantity of melt produced, with higher volume percentages occurring in the MS case study. Produced melts may migrate and support acidic volcanic activity.
Abstract: A hypabyssal kimberlite dike in southwestern Pennsylvania (USA), emplaced through Proterozoic basement and Phanerozic cover, contains a xenocryst and xenolith assemblage typical of material sampled within the subcontinental lithosphere, including xenocrysts of Cr-rich pyrope, magnesiochromite, Cr-rich diopside, and peridotite xenoliths. Temperatures and depths of equilibration of the clinopyroxene (840 ºC and 130 km to 1350 ºC and 170 km) indicate some sampling in the field of diamond stability. Diamonds have not been reported, however, and the chemistry of the garnet (lherzolite, Cr-poor megacryst, and Group II eclogite) and spinel (<56.0 wt.% Cr2O3) are consistent with diamond absence and the off-craton tectonic setting of the kimberlite. An unusual feature of this suite is that, unlike most mantle xenolith/xenocryst spinel, some of those from Masontown have an unusually high silica content (to 0.59 wt.% SiO2). The significance of the high silica content is unclear, but may be related to an ultrahigh-pressure precursor chromite polymorph with a calcium ferrite structure, which can accommodate Si in solid solution.
Abstract: n this study, we identify a giant circumferential mafic dyke swarm associated with the 135-75 Ma High Arctic Large Igneous Province (HALIP). Previously, a HALIP giant radiating mafic dyke swarm, with portions scattered across the Canadian high Arctic islands, northern Greenland, Svalbard and Franz Josef Land, was recognized in a pre-drift plate tectonic reconstruction of the Arctic region. The radiating swarm has been interpreted to focus above a mantle plume responsible for HALIP magmatism. The newly-recognized HALIP giant circumferential swarm has a centre that is near the focus of the HALIP radiating system, and hence, is likely related to the HALIP plume. Elements of the circumferential swarm are located in each of the four regions where the radiating system is found. The circumferential swarm has a quasi-circular or slightly elliptical geometry, an outer diameter of ~1600 km and an arc of ~220°. It is one of the largest giant circumferential dyke swarms recognized on Earth, and could be linked to the outer edge of the flattening plume head. It is also the first such swarm to have been identified by means of a plate tectonic reconstruction. Although giant circumferential dyke swarms appear to be relatively rare on Earth, possible analogues are common on Venus and are also found on Mars. On Venus giant circular or elliptical tectono-magmatic features, termed coronae, are characterized by an annulus of graben or fissures and prominent topography. Some coronae include a radiating graben-fissure system. Both radiating and circumferential graben may be underlain by dykes. If so, coronae could be analogues for terrestrial giant circumferential dyke swarms such as observed in the case of the HALIP.
Srivastava: Dyke Swarms of the World: a Modern Perspective, Springer, researchgate 56p. Pdf
India
dykes
Abstract: We present dyke swarm maps generated using Google Earth™ images, ArcGIS™, field data, and available geochronological ages of Neoarchean-Mesoproterozoic (ranging in age from ~2.80 to ~1.10 Ga) mafic dyke swarms and associated magmatic units of the different Archean cratons of the Indian shield which represent the plumbing system of Large Igneous Provinces (LIPs). The spatial and temporal distributions together with the trends of the dyke swarms provide important informations about geodynamics. Twenty four dyke swarms (17 have been precisely dated), mostly mafic in nature, have been mapped from the different cratons and named/re-named to best reflect their location, trend, distribution and distinction from other swarms. We have identified 14 distinct magmatic events during the Neoarchean-Mesoproterozoic in the Indian shield. These intraplate magmatic events (many of LIP scale) of the Indian shield and their matches with coeval LIPs on other crustal blocks suggest connections of the Indian shield within known supercontinents, such as Kenorland/Superia (~2.75-2.07 Ga), Columbia/Nuna (1.90-1.38 Ga), and Rodinia (1.20-0.72 Ga). However, further detailed U-Pb geochronology and associated paleomagnetism are required to come to any definite constraints on the position of the Indian cratons within these supercontinents.
Abstract: The subparallel maflc dykes of the Aorida-Durazno-S.José region (SW Uruguay) trend N60-80W and vary in thickness from 0.6 to 50 m. They are part of the mafic dyke swarms intrudlng granitic-gnelssic basement that were mappecl by BOSSI et ai. (1989), In an ares approximately 200 km In length and 100 km in bresdth. Plagioclass, augite, subcalclc augite (plgeonite) and opaques are the maln components of the dykes. Orthopyroxene and oIlvine are very rare. Blotite and homblende are secondary minerais. Quartz-feldspar Intergrowths occur In the coarser gralnecl dykes. The characterlstlc textures are subophitic and intersertal.
Dyke Swarms of the World: a modern perspective. Ed. Srivastava Springer, 49p. Pdf
Mantle
dyke swarms
Abstract: Giant circumferential dyke swarms have a primary geometry that is quasi-circular or quasi-elliptical. Examples and possible examples described previously or identified in this study have outer diameters that range from ~450 to ~2500 km. There has been little study of these features. Here, we present a global catalogue of giant circumferential dyke swarms and discuss their characteristics. All of the identified giant circumferential swarms are of mafic composition. Many, but not all, are associated with a roughly coeval giant radiating dyke swarm whose focus is at or near the centre of the circumferential system. As giant radiating swarms are usually interpreted to focus above mantle plume centres and form a key component of the plumbing system of large igneous provinces (LIPs), it is likely that giant circumferential swarms linked to radiating systems are also plume and LIP related. The largest giant circumferential swarms have diameters comparable to the diameters postulated for the flattened heads of plumes that have risen from the core-mantle boundary, suggesting that they may be associated with the outer edge of a flattening or flattened mantle plume head. Smaller giant circumferential swarms could be linked with small plumes from the mid-mantle or with the edge of a magmatic underplate above a plume head. Giant circumferential dyke swarms on Earth may be analogues of coronae on Venus and similar features on Mars. Coronae are large tectono-magmatic features that typically consist of a quasi-circular or quasi-elliptical graben-fissure system and associated topography (central uplift or depression, and circular rim or moat). In some instances, they are linked to a giant radiating graben-fissure system and LIP-scale volcanism. Both radiating and circumferential graben on Venus and Mars have been interpreted to be underlain by dykes.
Abstract: Based on investigation of Proterozoic mafic dike swarms of the Siberian Craton, we inferred how the geochemical and isotopic characteristics of dike swarms of dolerites of Large Igneous Provinces depend on their distance from the mantle plume head. It has been found that the dolerite parent melts near the mantle plume head correspond to OIB compositions. At significant distances from the plume, the initial melts of dolerites are generated in the subcontinental lithospheric mantle, which provides a wide range of their compositions differing from typical OIB and do not indicate directly the genetic relationship of these mafic rocks with the mantle plume.