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A complete structural model and kinematic history for distributed deformation in the Wharton Basin

A complete structural model and kinematic history for distributed deformation in the Wharton Basin
A complete structural model and kinematic history for distributed deformation in the Wharton Basin
The equatorial eastern Indian Ocean hosts a diffuse plate plate boundary, where widespread deformation accommodates the relative motion between the Indian, Australian and Capricorn sub-plates. We integrate IODP Expedition 362 borehole data, which for the first time provides an accurate, ground-truthed chronostratigraphy of the sedimentary sequence east of the Ninety East Ridge (NER), with 2D seismic reflection profiles and multibeam bathymetry to assess the styles of faulting between the NER and the Sunda subduction zone, timing of activity and comparison with physical and rheological properties. We identify four distinct fault sets east of the NER in the northern Wharton Basin. N-S (350-010°) orientated faults, associated with the N-S fracture zones formed at the now extinct Wharton spreading centre, are still active and have been continuously active since at least 10 Ma. NNE- and WNW-trending fault fabrics develop between the fracture zones. The orientations and likely sense of displacement on these three sets of faults defines a Riedel shear system responding to ~NNE-SSW left-lateral strike-slip activity at depth, demonstrated by the recent 2012 great intraplate earthquakes. We also find evidence of ~NE-SW reverse faults, similar in style to E-W reverse faults observed west of the NER, where reverse faulting is more dominant. We show that the activity of this strike-slip system increased ca. 7-9 Ma, contemporaneous with reverse faulting and intraplate deformation west of the NER.
IODP, Indian Ocean, diffuse plate boundary, intraplate deformation
0012-821X
Stevens, Duncan, Eliott
d8a1aedd-186d-47d5-a849-6c39fc9f0a1d
Mcneill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Delescluse, Matthias
54e1642b-965b-46a4-a87e-10174c21cba9
Chamot-Rooke, Nicolas
4ff9e1d0-d0d6-46c5-9ca9-c7b15377a209
Bull, Jonathan
974037fd-544b-458f-98cc-ce8eca89e3c8
Stevens, Duncan, Eliott
d8a1aedd-186d-47d5-a849-6c39fc9f0a1d
Mcneill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Delescluse, Matthias
54e1642b-965b-46a4-a87e-10174c21cba9
Chamot-Rooke, Nicolas
4ff9e1d0-d0d6-46c5-9ca9-c7b15377a209
Bull, Jonathan
974037fd-544b-458f-98cc-ce8eca89e3c8

Stevens, Duncan, Eliott, Mcneill, Lisa, Henstock, Timothy, Delescluse, Matthias, Chamot-Rooke, Nicolas and Bull, Jonathan (2020) A complete structural model and kinematic history for distributed deformation in the Wharton Basin. Earth and Planetary Science Letters, 538, [116218]. (doi:10.1016/j.epsl.2020.116218).

Record type: Article

Abstract

The equatorial eastern Indian Ocean hosts a diffuse plate plate boundary, where widespread deformation accommodates the relative motion between the Indian, Australian and Capricorn sub-plates. We integrate IODP Expedition 362 borehole data, which for the first time provides an accurate, ground-truthed chronostratigraphy of the sedimentary sequence east of the Ninety East Ridge (NER), with 2D seismic reflection profiles and multibeam bathymetry to assess the styles of faulting between the NER and the Sunda subduction zone, timing of activity and comparison with physical and rheological properties. We identify four distinct fault sets east of the NER in the northern Wharton Basin. N-S (350-010°) orientated faults, associated with the N-S fracture zones formed at the now extinct Wharton spreading centre, are still active and have been continuously active since at least 10 Ma. NNE- and WNW-trending fault fabrics develop between the fracture zones. The orientations and likely sense of displacement on these three sets of faults defines a Riedel shear system responding to ~NNE-SSW left-lateral strike-slip activity at depth, demonstrated by the recent 2012 great intraplate earthquakes. We also find evidence of ~NE-SW reverse faults, similar in style to E-W reverse faults observed west of the NER, where reverse faulting is more dominant. We show that the activity of this strike-slip system increased ca. 7-9 Ma, contemporaneous with reverse faulting and intraplate deformation west of the NER.

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Stevens_el_al-Structure_of_the_Wharton_Basin - Accepted Manuscript
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Accepted/In Press date: 9 March 2020
e-pub ahead of print date: 23 March 2020
Published date: 15 May 2020
Keywords: IODP, Indian Ocean, diffuse plate boundary, intraplate deformation

Identifiers

Local EPrints ID: 438727
URI: http://eprints.soton.ac.uk/id/eprint/438727
ISSN: 0012-821X
PURE UUID: 9757984a-931d-4a15-b7b5-45b46d764825
ORCID for Lisa Mcneill: ORCID iD orcid.org/0000-0002-8689-5882
ORCID for Timothy Henstock: ORCID iD orcid.org/0000-0002-2132-2514

Catalogue record

Date deposited: 23 Mar 2020 17:31
Last modified: 22 Nov 2021 02:46

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Contributors

Author: Lisa Mcneill ORCID iD
Author: Matthias Delescluse
Author: Nicolas Chamot-Rooke
Author: Jonathan Bull

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