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The importance of the transport system in shaping the growth and form of kimberlite volcanoes

McClintock, Murray; Ross, Pierre-Simon; White, James D. L. (2009). The importance of the transport system in shaping the growth and form of kimberlite volcanoes Lithos , vol. 112 , nº S 1. p. 465-472. DOI: 10.1016/j.lithos.2009.04.014.

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Résumé

Understanding the range of transport styles recorded by kimberlite deposits is key to describing the type and style of eruptions. Building a clear picture of the processes that shape deposits is essential for selecting exploration targets and evaluating the grade and value of diamond-bearing kimberlites. Variations in grade reflect differences in the diamond content of different magma parcels erupted during the lifetime of the kimberlite volcano, sorting during transport of eruption products, or re-working of diamonds during crater growth, cone collapse and erosion. The form of the kimberlite volcano is largely determined when the magma arrives near the surface. If magma comes into contact with external water, transport will be driven by a combination of magmatic gases + steam. From a diamond exploration perspective, the resulting deep diatremes make the most attractive targets because they survive erosion and form large geophysical anomalies. If water is too abundant, a tuff cone or tuff ring with no diatreme or a shallow one will form. On the other hand, if external water is very limited or if the conduit is rapidly sealed by chilled melt, the transport system will be driven by magmatic gases alone. The result will then be a spatter cone or cinder cone underlain by a dike, possibly with a related lava flow, but with no diatreme.

Type de document:
Mots-clés libres: kimberlites; diamètres; diamants; processus de transport; tri; phréeatomagmatisme
Centre: Centre Eau Terre Environnement
Date de dépôt: 16 janv. 2014 15:16
Dernière modification: 11 janv. 2017 20:53
URI: http://espace.inrs.ca/id/eprint/1895

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