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The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea

The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea
The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea
The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, 50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 105–106 yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.
Arabian Sea, backstripping, submarine fan
0025-3235
223-245
Clift, P.D.
0d70e344-e64e-416d-9e88-b7a17e18590e
Gaedicke, C.
a97e1d92-f52a-4b8a-acb0-5f6ec101800d
Edwards, R.A.
e733909a-1bd5-4302-ad8d-61e811b9d8fe
Lee, J.I.
57c8dc5e-5c1e-4623-918c-ede4b58ac0c1
Hildebrand, P.
d03d2bcc-03c3-4cd1-ac14-79e83bea3b8f
Amjad, S.
0862beda-fa25-4287-9e49-c359298744f9
White, R.S.
3919ea9f-a09d-43c2-93fa-c7986055e486
Clift, P.D.
0d70e344-e64e-416d-9e88-b7a17e18590e
Gaedicke, C.
a97e1d92-f52a-4b8a-acb0-5f6ec101800d
Edwards, R.A.
e733909a-1bd5-4302-ad8d-61e811b9d8fe
Lee, J.I.
57c8dc5e-5c1e-4623-918c-ede4b58ac0c1
Hildebrand, P.
d03d2bcc-03c3-4cd1-ac14-79e83bea3b8f
Amjad, S.
0862beda-fa25-4287-9e49-c359298744f9
White, R.S.
3919ea9f-a09d-43c2-93fa-c7986055e486

Clift, P.D., Gaedicke, C., Edwards, R.A., Lee, J.I., Hildebrand, P., Amjad, S. and White, R.S. (2002) The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea. Marine Geophysical Researches, 23 (3), 223-245. (doi:10.1023/A:1023627123093).

Record type: Article

Abstract

The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, 50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 105–106 yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.

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More information

Published date: May 2002
Keywords: Arabian Sea, backstripping, submarine fan

Identifiers

Local EPrints ID: 58880
URI: http://eprints.soton.ac.uk/id/eprint/58880
ISSN: 0025-3235
PURE UUID: 34da4da8-537b-486c-ae76-ce721c881f8b

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Date deposited: 18 Aug 2008
Last modified: 13 Mar 2019 20:31

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Contributors

Author: P.D. Clift
Author: C. Gaedicke
Author: R.A. Edwards
Author: J.I. Lee
Author: P. Hildebrand
Author: S. Amjad
Author: R.S. White

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