Geochemistry of Deccan Tholeiite Flows and Dykes of Elephanta Island: Insights into the Stratigraphy and Structure of the Panvel Flexure Zone, Western Indian Rifted Margin
| Autor: | Gopal W. Joshi, Ciro Cucciniello, Hrishikesh Samant, Hetu Sheth, Bibhas Sen, Wencke Wegner, Vanit Patel, Christian Koeberl |
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| Přispěvatelé: | Patel, Vanit, Sheth, Hetu, Cucciniello, Ciro, Joshi, Gopal W., Wegner, Wencke, Samant, Hrishikesh, Sen, Bibha, Koeberl, Christian |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
geochemical stratigraphy
volcanism 010504 meteorology & atmospheric sciences Lava lcsh:QE1-996.5 Geochemistry India Crust 010502 geochemistry & geophysics 01 natural sciences volcanic rifted margin lcsh:Geology Continental margin Stratigraphy tholeiite Lithosphere Flood basalt Deccan Traps General Earth and Planetary Sciences Ankaramite Geology flood basalt 0105 earth and related environmental sciences |
| Zdroj: | Geosciences Volume 10 Issue 4 Geosciences, Vol 10, Iss 4, p 118 (2020) |
| ISSN: | 2076-3263 |
| DOI: | 10.3390/geosciences10040118 |
| Popis: | Elephanta Island near Mumbai is an important area for understanding the stratigraphic and structural framework of the Deccan flood basalt province in the tectonically disturbed Panvel flexure zone on the western Indian rifted margin. Elephanta exposes a west-dipping, 66&ndash 65 Ma sequence of tholeiitic lava flows and dykes. Geochemical correlations with the thick, horizontal, 66&ndash 65 Ma Western Ghats sequence to the east show that lava flows of the Khandala and Ambenali formations are present at Elephanta, with two lava flows probably being locally derived. The Elephanta tholeiites have experienced crystal fractionation and accumulation, particularly of olivine. They have eNd(t) ranging from +5.4 to &minus 7.9 and (87Sr/86Sr)t from 0.70391 to 0.70784, with most tholeiites little contaminated by continental lithosphere, probably lower crust. Field and geochemical data indicate a normal fault along the central part of Elephanta with a 220 m downthrow, consistent with a domino-type block-faulted structure of Elephanta, and the surrounding area as previously known. Seventeen of the 20 analyzed Elephanta intrusions, striking ~N&ndash S, belong to the Coastal dyke swarm of the western Deccan province. Several of these are probable feeders to the Ambenali Formation in the Western Ghats sequence, requiring reconsideration of the current view that the voluminous Wai Subgroup lavas of the Western Ghats were erupted without organized crustal extension. East&ndash west-directed extensional strain was already active at 66&ndash 65 Ma along this future (62.5 Ma) rifted continental margin. A young (~62 Ma) ankaramite dyke on Elephanta Island is a probable feeder to the Powai ankaramite flow in the 62.5 Ma Mumbai sequence 20 km to the northwest. |
| Databáze: | OpenAIRE |
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