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Authors
Affiliations
1 Department of Earth Sciences, Indian Institute of Technology, Bombay, Powai, Mumbai - 400076, IN
2 Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, US
3 MR Division, R & C Directorate, ACC Ltd., LBS Marg, Thane - 400 604, IN
4 University Science Instrumentation Centre, University of Roorkee, Roorkee - 247667, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 57, No 1 (2001), Pagination: 31-38
Abstract
Massif type anorthositic rocks in Bolangir area of the Eastern Ghats belt contain garnet porphyroblasts, which are surrounded by reaction coronas. The corona usually comprises a vermicular intergrowth, which in one instance consists of radial orthopyroxene and anorthite-rich plagioclase, and in another of radial chlorite and anorthite-rich plagioclase. Some of the anorthositic rocks are layered with thin discontinuous mafic layers of clinopyroxene and biotite. Notable is the presence of retrograde ferro-anthophyllite in the mafic layers of some of the rocks. Thermobarometric calculations using assemblage in the orthopyroxene corona indicate decompression from minimum peak P-T condition of 8 kbar and 700°C.
Keywords
Anorthosite, Metamorphism, Corona, Decompression, Bolangir, Eastern Ghats.
