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Early (pre-8 Ma) fault activity and temporal strain accumulation in the central Indian Ocean

Early (pre-8 Ma) fault activity and temporal strain accumulation in the central Indian Ocean
Early (pre-8 Ma) fault activity and temporal strain accumulation in the central Indian Ocean
The diffuse deformation zone in the central Indian Ocean is the classical example of distributed deformation of the oceanic lithosphere with shortening between the Indian and Capricorn plates manifest as reverse faulting (5–10 km spaced faults) and long-wavelength (100–300 km) folding. The onset of this deformation is commonly regarded as a key far-field indicator for the start of major uplift of the Himalayas and Tibet, some 4000 km further to the north, due to increased deviatoric stresses within the wider India-Asia area. There has been disagreement concerning the likely timing for the onset of deformation between plate motion inversions and seismic reflection-based studies. In the present study, fault displacement data from seismic reflection profiles within the central Indian Ocean demonstrate that compressional activity started much earlier, at around 15.4–13.9 Ma. We reconstruct that 12% of the total reverse fault population had been activated, and 14% of the total strain accumulated, prior to a sharp increase in the deformation rate at 8.0–7.5 Ma. There is no evidence for any regional unconformity before 8.0–7.5 Ma, early shortening was accommodated by activity on single isolated fault blocks. Total strain estimates derived are more variable and complex than those predicted from plate inversion and do not show simple west to east increase.
tectonics, diffuse plate boundary, faulting, Indian Ocean, Himalaya
0091-7613
227-230
Krishna, K.S.
fa339710-534a-4d69-9392-d83eddea9a76
Bull, J.M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Scrutton, R.A.
95eded4e-f5ed-4ecc-8cd7-ecd916dc10a6
Krishna, K.S.
fa339710-534a-4d69-9392-d83eddea9a76
Bull, J.M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Scrutton, R.A.
95eded4e-f5ed-4ecc-8cd7-ecd916dc10a6

Krishna, K.S., Bull, J.M. and Scrutton, R.A. (2009) Early (pre-8 Ma) fault activity and temporal strain accumulation in the central Indian Ocean. Geology, 37 (3), 227-230. (doi:10.1130/G25265A.1).

Record type: Article

Abstract

The diffuse deformation zone in the central Indian Ocean is the classical example of distributed deformation of the oceanic lithosphere with shortening between the Indian and Capricorn plates manifest as reverse faulting (5–10 km spaced faults) and long-wavelength (100–300 km) folding. The onset of this deformation is commonly regarded as a key far-field indicator for the start of major uplift of the Himalayas and Tibet, some 4000 km further to the north, due to increased deviatoric stresses within the wider India-Asia area. There has been disagreement concerning the likely timing for the onset of deformation between plate motion inversions and seismic reflection-based studies. In the present study, fault displacement data from seismic reflection profiles within the central Indian Ocean demonstrate that compressional activity started much earlier, at around 15.4–13.9 Ma. We reconstruct that 12% of the total reverse fault population had been activated, and 14% of the total strain accumulated, prior to a sharp increase in the deformation rate at 8.0–7.5 Ma. There is no evidence for any regional unconformity before 8.0–7.5 Ma, early shortening was accommodated by activity on single isolated fault blocks. Total strain estimates derived are more variable and complex than those predicted from plate inversion and do not show simple west to east increase.

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More information

Published date: April 2009
Keywords: tectonics, diffuse plate boundary, faulting, Indian Ocean, Himalaya

Identifiers

Local EPrints ID: 65656
URI: http://eprints.soton.ac.uk/id/eprint/65656
ISSN: 0091-7613
PURE UUID: 8dc09e33-ae52-4dc8-b928-f381d8da71bf
ORCID for J.M. Bull: ORCID iD orcid.org/0000-0003-3373-5807

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Date deposited: 04 Mar 2009
Last modified: 14 Mar 2024 02:36

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Contributors

Author: K.S. Krishna
Author: J.M. Bull ORCID iD
Author: R.A. Scrutton

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