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Near N-S paleo-extension in the western Deccan region, India: Does it link strike-slip tectonics with India-Seychelles rifting?

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Title Near N-S paleo-extension in the western Deccan region, India: Does it link strike-slip tectonics with India-Seychelles rifting?
 
Creator MISRA, AA
BHATTACHARYA, G
MUKHERJEE, S
BOSE, N
 
Subject Deccan large igneous province
Strike-slip fault
Brittle shear
Paleostress
India-Seychelles rifting
LARGE IGNEOUS PROVINCE
CRETACEOUS-TERTIARY BOUNDARY
NORTHEASTERN ARABIAN SEA
KOYNA SEISMIC ZONE
MAFIC DIKE SWARM
FLOOD BASALTS
PALEOSTRESS ANALYSIS
CONTINENTAL-MARGIN
SHEAR-ZONE
VOLCANIC PROVINCE
 
Description This is the first detailed report and analyses of deformation from the W part of the Deccan large igneous province (DLIP), Maharashtra, India. This deformation, related to the India-Seychelles rifting during Late Cretaceous-Early Paleocene, was studied, and the paleostress tensors were deduced. Near N-S trending shear zones, lineaments, and faults were already reported without significant detail. An E-W extension was envisaged by the previous workers to explain the India-Seychelles rift at similar to 64 Ma. The direction of extension, however, does not match with their N-S brittle shear zones and also those faults (sub-vertical, similar to NE-SW/similar to NW-SE, and few similar to N-S) we report and emphasize in this work. Slickenside-bearing fault planes, brittle shear zones, and extension fractures in meso-scale enabled us to estimate the paleostress tensors (directions and relative magnitudes). The field study was complemented by remote sensing lineament analyses to map dykes and shear zones. Dykes emplaced along pre-existing similar to N-S to similar to NE-SW/similar to NW-SE shears/fractures. This information was used to derive regional paleostress trends. A similar to NW-SE/NE-SW minimum compressive stress in the oldest Kalsubai Subgroup and a similar to N-S direction for the younger Lonavala, Wai, and Salsette Subgroups were deciphered. Thus, a similar to NW/NE to similar to N-S extension is put forward that refutes the popular view of E-W India-Seychelles extension. Paleostress analyses indicate that this is an oblique rifted margin. Field criteria suggest only similar to NE-SW and similar to NW-SE, with some similar to N-S strike-slip faults/brittle shear zones. We refer this deformation zone as the "Western Deccan Strike-slip Zone" (WDSZ). The observed deformation was matched with offshore tectonics deciphered mainly from faults interpreted on seismic profiles and from magnetic seafloor spreading anomalies. These geophysical findings too indicate oblique rifting in this part of the W Indian passive margin. We argue that the Seychelles microcontinent separated from India only after much of the DLIP erupted. Further studies of magma-rich passive margins with respect to timing and architecture of deformation and emplacement of volcanics are required.
 
Publisher SPRINGER
 
Date 2014-12-28T11:57:31Z
2014-12-28T11:57:31Z
2014
 
Type Article
 
Identifier INTERNATIONAL JOURNAL OF EARTH SCIENCES, 103(6)1645-1680
1437-3254
1437-3262
http://dx.doi.org/10.1007/s00531-014-1021-x
http://dspace.library.iitb.ac.in/jspui/handle/100/16417
 
Language English