Feldspars and Pryoxenes from the Charnockite Series of Visakhapatnam Area, Andhra Pradesh, India1

M. S. Murty
Geology Department, Sri Venkateswara University, Tirupati, India
1This forms a summary of part of the thesis accepted for the degree of Doctor of Science by the Andhra University, Waltair, in 1961.

Summary: A twin-law study of the plagioclase indicated metamorphic origin of the charnockites and volcanic origin of the basic members of the charnockite series. The original volcanic products have been influenced by the later metamorphism, resulting in the various basic members. The twinning in the plagioclase is considered to be primary. The perthite in the charnockite is of orthoclase variety and indicates a higher temperature of formation than the charnockites of other areas containing microcline. The orthopyroxene in the charnockite series is hypersthene and the clinopyroxene is sahlite. Hypersthene is inferred to have formed at the expense of sahlite, hornblende, biotite, and garnet.

Mineralogical Magazine; June 1965 v. 35; no. 270; p. 393-400; DOI: 10.1180/minmag.1965.035.270.13
© 1965, The Mineralogical Society
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