Geology of the Elephanta Island fault zone, western Indian rifted margin, and its significance for understanding the Panvel flexure
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- 作者：Hrishikesh Samant ; Ashwin Pundalik ; Joseph D’souza…
- 关键词：Flood volcanism ; Deccan traps ; Panvel flexure ; Mumbai ; Elephanta Island ; faulting
- 刊名：Journal of Earth System Science
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：126
- 期：1
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Earth Sciences, general; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics);
- 出版者：Springer India
- ISSN：0973-774X
- 卷排序：126
文摘
The Panvel flexure is a 150-km long tectonic structure, comprising prominently seaward-dipping Deccan flood basalts, on the western Indian rifted margin. Given the active tectonic faulting beneath the Panvel flexure zone inferred from microseismicity, better structural understanding of the region is needed. The geology of Elephanta Island in the Mumbai harbour, famous for the ca. mid-6th century A.D. Hindu rock-cut caves in Deccan basalt (a UNESCO World Heritage site) is poorly known. We describe a previously unreported but well-exposed fault zone on Elephanta Island, consisting of two large faults dipping steeply east–southeast and producing easterly downthrows. Well-developed slickensides and structural measurements indicate oblique slip on both faults. The Elephanta Island fault zone may be the northern extension of the Alibag–Uran fault zone previously described. This and two other known regional faults (Nhava–Sheva and Belpada faults) indicate a progressively eastward step-faulted structure of the Panvel flexure, with the important result that the individual movements were not simply downdip but also oblique-slip and locally even rotational (as at Uran). An interesting problem is the normal faulting, block tectonics and rifting of this region of the crust for which seismological data indicate a normal thickness (up to 41.3 km). A model of asymmetric rifting by simple shear may explain this observation and the consistently landward dips of the rifted margin faults.