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Petrological observations on alkali syenites of Kunavaram, A. P., India

Published online by Cambridge University Press:  01 May 2009

Mihir K. Bose ,
S. Chakravarti  and
A. Sarkar
Mihir K. Bose
Affiliation:
Department of Geology, Presidency College, Calcutta 12, India
S. Chakravarti
Affiliation:
Department of Geology, Presidency College, Calcutta 12, India
A. Sarkar
Affiliation:
Department of Geology, Presidency College, Calcutta 12, India
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Summary

The alkali syenite assemblage of Kunavaram, Khammam district, Andhra Pradesh in south-eastern India, comprises perthite syenite and nepheline syenite. The massive perthite syenite (locally grading to alaskite) is fringed on either side by foliated nepheline syenite, the latter developing composite gneisses along the contact zones with the country rocks. The syenites are essentially hypersolvus although the alkali feldspar, the dominant constituent of the rocks, shows varying degrees of unmixing and Al/Si order. The mafic constituents (e.g. sodic pyroxene, amphibole and biotite) are appreciably rich in ferrous iron. Mineralogical and chemical data suggest that the primary crystallization characteristics of the syenites were not totally obliterated during the post-magmatic history of the pluton.

Type
Articles
Information
Geological Magazine , Volume 108 , Issue 4 , July 1971 , pp. 273 - 280
Copyright
Copyright © Cambridge University Press 1971

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