Kimberlite Fields and Provinces: Their Tectonic Setting
Kimberlites are products of continental intra-plate magmatism. Occurrences have not been described from oceanic environments or young fold belts. Clifford (1966) initially recognized that areas of kimberlite magmatism are confined to regions of the continental crust that are underlain by old cratons. Commonly these regions consist of a core of very old (>2.4 gigayear) rocks to which have been fused younger (>1.0 Ga) belts of deformed rocks. This process of accretion of mobile belts to the older cores is termed cratonization. The resulting structures subsequently act as rigid blocks with respect to younger tectonic events. Cratons are typically covered with Phanerozoic platform sediments and associated continental volcanics. In response to epeirogenic uplift and downwarping these rocks are faulted and/or deformed into broad basins and swells (syneclises and anteclises). It is within these platform rocks that kimberlite magmatism, especially diatreme formation, finds its greatest expression. Relatively few important kimberlite provinces are known from the exposed cores of cratons, the principal examples being the Colorado—Wyoming (McCallum et al. 1975) and the Tanzanian (Mannard 1962) kimberlite provinces.
KeywordsFault Zone Mantle Plume Alkaline Rock Alkaline Magmatism Platform Rock
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