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Sethna, B. S.
- Iron-Titanium Oxide Geothermometry for some Deccan Trap Tholeiitic Basalts, India
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Authors
Affiliations
1 Department of Geology, St. Xavier's College, Bombay 400 001, IN
2 Mineralogisch Institut, Albert-Ludwigs Universitat, D-7800 Freiburg i BR, DE
1 Department of Geology, St. Xavier's College, Bombay 400 001, IN
2 Mineralogisch Institut, Albert-Ludwigs Universitat, D-7800 Freiburg i BR, DE
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 29, No 5 (1987), Pagination: 483-488Abstract
The oxygen fugacity and temperature of equilibration of the iron-titanium oxides for thirty samples of basaltic rocks, taken from different parts of the Tholeiitic Flood Basalt Province of Deccan Trap (Tertiary); are given. Temperatures range from 950° to 1200°C and oxygen fugacity from 9 to 12 (as -log10). Picritic basalts from Igatpuri along the Western Ghats, that form compound lava fiows, give lower temperatures of equilibration of the iron-titanium oxides (considered to represent the liquidus of the host rock) as compared to the simple thin lava flows of normal tholeiitic basalt from the eastern parts of the Deccan trap outcrop.- Petrology of Deccan Trap Basalts of the Western Ghats Around Igatpuri and their Petrogenetic Significance
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Authors
S. F. Sethna
1,
B. S. Sethna
1
Affiliations
1 Department of Geology, St. Xavier's College, Bombay 400 001, IN
1 Department of Geology, St. Xavier's College, Bombay 400 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 35, No 6 (1990), Pagination: 631-643Abstract
Major and trace element analyses of sixteen samples of basaltic rocks. representing a vertical section of 1600m (from Bhiwandi to Jgatpuri and beyond into Kalsubai Hill) of the Western Ghats, are presented. The analyses show a very wide variation in Mg number, and indicate very distinct differentiation trends. The MgO contents vary between 4.55% and 12.43% showing a continuous variation from tholeiitic basalts to picrite basalts that are enriched in phenocrystal olivine. It is shown that the MgO-rich picritic basalts have differentiated to form the normal low-MgO basalts. It is also shown that the very high contents of MgO is due to accumulation of phenocrysta] olivine.Keywords
Crustal Contamination, Deccan Traps, Petrocbemistry, Petrography, Picrite, Western Ghats, Maharashtra.- Geology and Petrography of the Intrusives in the Deccan Trap of Central and South-Eastern Saurashtra, India
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Authors
Affiliations
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 57, No 3 (2001), Pagination: 249-256Abstract
Forty-five major dykes intruding the Deccan Trap were studied in the central and south-eastern parts of Saurashtra. There are some distinct structural differences seen between the area north of Amreli and that south of Amreli. The lava flows north of Amreli are practically horizontal, while south of Amreli they seem to be forming a major southerly-plunging antiform. In the area north of Amreli, dolerite dykes are invariably enriched in fresh olivine and are associated with one ankaramite dyke, a hybrid monzodolerite and a stock-like body of essexite (foid monzogabbro). In the area south of Armeli, dolerites are generally olivine free but in a few samples altered olivine is present. These dolerites are associated with rhyolitic dykes, which invariably contain microphenocrysts of quartz and are thus described as quartz porphyries.Keywords
Deccan Trap, Intrusives, Petrography, Structure, Saurashtra.- Petrology and Mineralogy of Ankaramite in the Deccan Volcanic Province of Rajkot District, Saurashtra, Gujarat
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Authors
Affiliations
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 61, No 1 (2003), Pagination: 97-100Abstract
The occurrence of ankaramite in the Deccan Volcanic Province of Saurashtra is reported here. The ankaramite occurs as a small dyke intruding into horizontal basalt flows. Petrographically it is characterised by the presence of large phenocrysts of ctinopyroxene (chromian diopside) and olivine (Fo83) in a groundmass of plagioclase (An60), iron oxides and accessory brown amphibole (kaersutite). Chemically it is characterised by enrichment in high field strength and light rare earth elements as compared to the picritic olivine dolerites of the area. It is concluded that the ankaramite magma represents a primitive sample of High-Ti type of tholeiitic basaltic magma while majority of the olivine dolerites and dolerites found in the area are representative of Low-Ti type of tholeiitic magma.Keywords
Deccan Traps, Ankaramite, Rajkot, Saurashtra, Gujarat.- Monzodolerite Dyke in the Deccan Traps of Saurashtra
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Authors
Affiliations
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN
1 Department of Geology, St. Xavier's College, Mumbai - 400 001, IN