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Authors
Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 60, No 1 (2002), Pagination: 67-74
Abstract
Presence of several morphologies of quench olivine crystals, which provide important clues on cooling rate(s) of magma, are reported here in a basaltic dyke, from the Precambrian gneissic terrain of Schirmacher Oasis, Queen Maud Land, East Antarctica. The dyke, composed of plagioclase, clinopyroxene, olivine, magnetite and glass, shows intergranular texture. It is alkali basalt in composition with low silica (SiO2 = 46.20-47.20) and negative Nb anomaly. The morphologies of quench olivine crystals suggcst rapid cooling of the basaltic magma approximately at 15-80°C/hour. Further, the delicate nature of these quench olivine crystals, confined mostly to the glassy margins of the dyke, also suggest in situ crystallisation.
Keywords
Basaltic Dyke, Quench Olivine Crystals, Petrography, Geochemistry, Schirmacher Oasis, East Antarctica.
