Petrology of offshore basalts of Bombay Harbour area, West Coast of India

Recent marine geological and geophysical surveys indicate that the Deccan Traps extend to the offshore area of Bombay. Cores from bore holes in Deccan Traps collected from Bombay Harbour have been classified as basalts, olivine basalts, spilitic basalts, and dolerites. Plagioclase composition of bas...

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Bibliographic Details
Published in:Indian journal of marine sciences 1988-09, Vol.17 (3), p.208-213
Main Author: KARISIDDAIAH, S. M
Format: Article
Language:English
Subjects:
Crystalline rocks
Earth sciences
Earth, ocean, space
Exact sciences and technology
Igneous and metamorphic rocks petrology, volcanic processes, magmas
Marine
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Summary:Recent marine geological and geophysical surveys indicate that the Deccan Traps extend to the offshore area of Bombay. Cores from bore holes in Deccan Traps collected from Bombay Harbour have been classified as basalts, olivine basalts, spilitic basalts, and dolerites. Plagioclase composition of basalts ranges from An sub(72-60) to An sub(40-45) (while in spilitic basalts it is in the range of 10-32%); augite (2V sub(z) = 30 degree - 50 degree ), fresh and altered olivine with ubiquitous magnetite and devitrified glass are conspicuous. The chemical data indicate that the basalts are tholeiitic. Secondary minerals encountered support the view that the basalts are spilitised. Basalts of this area show affinities to both continental and oceanic types especially in the abundances of TiO sub(2) (1.21-2.51%), and therefore may be of transitional nature.
ISSN:0379-5136
0975-1033