Kimberlites and Alkalic Ultrabasic Rocks in Cra Tonic Regions
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چکیده
ONE petrological approach to upper mant le studies is to determine which ultramafic rocks represent mantle material. Ultramafic rocks occur in a variety of field and petrographic associations : in recent reviews, Wyllie [1967b, 1968] outlined eleven petrographic associations, some with subdivisions. In this summary, it is convenient to consider these in four larger groups: (1) layered, stratiform, and other intrusions involving gabbro or diabase, together with accumulations or concentrations of mafic minerals; (2) the alkalic rocks, including kimberlites, mica peridotites, members of ring complexes, and ultrabasic Java flows; (3) the several serpentinite-peridotite associations often classified together as alpine-type int rusions; ( 4) serpentinites and peridotites of the oceanic regions. It is generally agreed that the ultramafic rocks of group 1 were formed from mantlederived basaltic magma, and therefore they
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Comments on: ‘Petrogenesis of Proterozoic Lamproites and Kimberlites from the Cuddapah Basin and Dharwar Craton, Southern India’
Kimberlites intrude the late Archaean eastern Dharwar Craton in two spatially separate fields ( 150 km apart, near Mahbubnagar in the north and Anantapur in the south) to the west of the Proterozoic Cuddapah Basin in southern India. Two lamproite bodies intrude the thick Cuddapah Basin sediments near Chelima and Zangamarajupalle, and a third occurs just outside the present NE margin of the basi...
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