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Porphyritic plagioclase–hornblende–pyroxene granulite from charnockitic rocks of Chipurupalli, Visakhapatnam district, Andhra Pradesh, South India

Published online by Cambridge University Press:  05 July 2018

K. S. R. Rao
Affiliation:
Department of Geology, Andhra University, Waltair, India
A. T. Rao
Affiliation:
Department of Geology, Andhra University, Waltair, India
A. Sriramadas
Affiliation:
Department of Geology, Andhra University, Waltair, India

Summary

An unusual occurrence of porphyritic plagioclase-hornblende-pyroxene granulite (porphyritic basic charnockite) has been observed within the ‘Charnockite region’ of the Eastern Ghats of the Precambrian formations of India. From the X-ray and chemical data the phenocrysts are considered to be augite phenocrysts. Based on petrographic and chemical evidence it is inferred that the basic charnockites of Chipurupalli area in Visakhapatnam district are formed from tholeiitic magma as a gabbroic mass under deep seated plutonic conditions. The gabbroic mass has been recrystallized as plagioclase-hornblende-pyroxene granulite due to later metamorphism, leaving most of the phenocrysts unaffected.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1969

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