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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Emplacement
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.
Emplacement is a subset of the key word "volcanism" and flags scientific articles dealing with the ascent and eruption of kimberlite pipes, the primary source of bedrock hosted diamonds. These articles tend to focus more on the physical model as to how a kimberlite gets "emplaced" than the classification of the various parts of an emplaced kimberlite.
Greg Stott is recipient of Provincial Geologist's Medal. He has been involved in an interpretation of the Archean & Proterozoic basement rocks James Bay Lowlands
Ontario Ministry of Northern Development and Mines, August 29, Release no. 134, 1p.
In vent column collapse as an alternative model for massive volcaniclastic kimberlite emplacement: an example from the Fox kimberlite, Ekati diamond mine.
Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 90-102. reply in press 17p.
Rapid magma ascent and short eruption durations in the Lake Natron-Engaruka monogenetic volcanic field ( Tanzania): a case study of the olivine melilitic Pello Hill scoria cone.
Journal of Volcanology and Geothermal Research, Vol. 247-248, Dec. 1, pp. 16-25.
GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., Keynote abstract
Technology
Emplacement
Abstract: The study develops a new approach utilizing parameters of trigonal etch pits on diamond crystals to infer the conditions of diamond residence in kimberlite magma. Diamond crystals from dissolution experiments conducted at 1 GPa and 1150-1350 °C in the presence of H2O-rich or CO2-rich fluid were studied with atomic force microscopy (AFM). The AFM data of resorbed diamond surfaces show that much deeper surface relief was produced in CO2 fluid. It also clearly distinguishes the profiles of the trigonal etch pits forming regular flat-bottomed trigons in H2O fluid, and round- or pointed-bottomed trigons in CO2 fluid. The relationship between the diameter and the depth of the trigonal pits is found to be another important indicator of the fluid composition. Dissolution in H2O fluid develops trigons with constant diameter and variable depth where the diameter increases with temperature. Trigons developed in CO2 fluid have a large range of diameters showing a strong positive correlation with the depth. The developed criteria applied to the natural diamond crystals from three Ekati Mine kimberlites indicate significant variation in CO2-H2O ratio and temperature of their magmatic fluid. This conclusion based on diamond resorption agrees with the mineralogy of microphenocrysts and groundmass of the studied kimberlites offering new method to study crystallization conditions of kimberlite magma.
The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 14p.
Mantle
Emplacement
Abstract: Various models of near-surface kimberlite pipe emplacement have been proposed over the years. These include a top-down, phreatomagmatic model, a bottom-up, embryonic pipe model and three top-down explosive dyke models. All of these models consider kimberlites as essentially the same rock type. However. different kimberlites have different pipe shapes and contain different rock types with very specific mineral assemblages and textures and therefore are likely to have been emplaced by different processes. Some authors have considered local geological differences as the principal reason for the contrasting geology but others argue that, while geological differences might contribute locally the petrographic peculiarities of particular kimberlites may be due mainly to inherent compositional differences specifically in the ratios of juvenile CO2 and H20.
Geological Society of London, Special Publication no. 446 on line available
Global
Emplacement models
Abstract: Most kimberlite maar-diatreme volcanoes erupted during the Tertiary or earlier and therefore their tephra rings and, less often, their near-surface diatreme-filling deposits have usually been eliminated by erosion. Poorly eroded Quaternary non-kimberlite maar-diatreme volcanoes, especially those of mafic and ultramafic magma types, have the same diatreme size range (diameter and depth) as kimberlite pipes and show similar internal volcaniclastic diatreme lithofacies. In addition, these young volcanoes often have a more or less preserved tephra ring consisting of hundreds to perhaps a few thousand thin tephra beds. Volcanological analyses of the xenolith-rich primary volcaniclastic deposits both within these diatremes and in the tephra ring beds reflect phases of explosive pipe growth and are of convincingly phreatomagmatic origin. The similarities between non-kimberlite pipes and kimberlite pipes suggest to some researchers that phreatomagmatic processes were also responsible for pipe excavation processes in kimberlite maar-diatreme volcanoes. In contrast, other researchers have suggested that kimberlite maar-diatreme volcanoes were emplaced largely by magmatic processes as a consequence of exsolution and the explosive expansion of juvenile volatiles. We therefore analysed and compared some key geological features of kimberlite and ultrabasic to basic ‘basaltic’ maar-diatreme volcanoes to determine similarities and differences with respect to their emplacement behaviour.
Abstract: This contribution presents an updated descriptive scheme for magmaclasts in kimberlite, resulting from over 40 combined years of mapping, logging, and petrographic studies by the authors of hundreds of kimberlites and related rocks globally. Systematic description of the essential characteristics of magmaclasts enables their identification, classification and interpretation. Magmaclasts are fluidal-shaped bodies of kimberlite magma (now solidified) formed by any process of magma disruption prior to solidification. The key characteristics used to discriminate the two main varieties, melt segregations and melt-bearing pyroclasts, are explained and illustrated, as well as the features of melt-bearing pyroclasts in the two main classes of pyroclastic kimberlite. Accurate classification of magmaclasts in coherent and volcaniclastic kimberlites is fundamental for the development of valid geological models in support of exploration, evaluation and mine planning. Magmaclasts are used to determine parental magma type, the textural-genetic classification of the infills of kimberlite bodies, the presence of different eruptive phases (and mixing between them), and the emplacement history of a kimberlite. They can also provide insight on potential modification of the inherent diamond distribution of a kimberlite.
