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Morphostructure of an incipient subduction zone along a transform plate boundary: Puysegur Ridge and Trench

Morphostructure of an incipient subduction zone along a transform plate boundary: Puysegur Ridge and Trench
Morphostructure of an incipient subduction zone along a transform plate boundary: Puysegur Ridge and Trench
Multibeam bathymetric and geophysical data reveal a major strike-slip fault that extends along the summit of the Puysegur Ridge east of the Puysegur Trench. The northward structural development of this ridge-trench system illustrates the evolution of an incipient subduction zone along a transform plate boundary that has been subjected to increasing transverse shortening during the past 10 m.y. At the southern end of the trench, where subduction has not yet started, the Puysegur Ridge has a narrow (<50 km) steep-sided cross section, and the axial strike-slip fault separates a shallow (125–625 m), flat-topped eastern crest from a deeper (400–1600 m) western crest; these characteristics indicate differential uplift during the initial stage of shortening. On the lower plate an incipient, 5.2-km-deep trench developed in conjunction with normal and reverse faults, suggesting strong interplate coupling across the trench. Northward, the ridge broadens linearly to 80 km wide, its western flank has locally collapsed, and the ridge summit has subsided, possibly by 1.5 km, suggesting that the interplate coupling decreases and that a Benioff zone is being formed. Concomitant to the northward ridge evolution, the trench deepens to 6.2 km and normal fault throws increase along its outer wall, indicating greater flexure of the downgoing plate.
0091-7613
519-522
Collot, J-Y.
feadbc78-87fb-4558-beaf-6805b0e71482
Lamarche, G.
79c06f89-5fdb-40dc-bd37-eb4e69ee8fb0
Wood, R.A.
c135e2f0-fa83-4691-9c34-ac3d5de0c756
Delteil, J.
94a263c6-14df-4bca-aa2a-bcc68714a6fb
Sosson, M.
f19bc545-5f94-42fa-a9d9-be4f5105aa70
Lebrun, J-F.
f4f1c6a6-bc53-42ea-ba43-7b3b9ca16192
Coffin, M.F.
b8285650-5efd-4129-ae91-1cf3f5911e89
Collot, J-Y.
feadbc78-87fb-4558-beaf-6805b0e71482
Lamarche, G.
79c06f89-5fdb-40dc-bd37-eb4e69ee8fb0
Wood, R.A.
c135e2f0-fa83-4691-9c34-ac3d5de0c756
Delteil, J.
94a263c6-14df-4bca-aa2a-bcc68714a6fb
Sosson, M.
f19bc545-5f94-42fa-a9d9-be4f5105aa70
Lebrun, J-F.
f4f1c6a6-bc53-42ea-ba43-7b3b9ca16192
Coffin, M.F.
b8285650-5efd-4129-ae91-1cf3f5911e89

Collot, J-Y., Lamarche, G., Wood, R.A., Delteil, J., Sosson, M., Lebrun, J-F. and Coffin, M.F. (1995) Morphostructure of an incipient subduction zone along a transform plate boundary: Puysegur Ridge and Trench. Geology, 23 (6), 519-522. (doi:10.1130/0091-7613(1995)023<0519:MOAISZ>2.3.CO;2).

Record type: Article

Abstract

Multibeam bathymetric and geophysical data reveal a major strike-slip fault that extends along the summit of the Puysegur Ridge east of the Puysegur Trench. The northward structural development of this ridge-trench system illustrates the evolution of an incipient subduction zone along a transform plate boundary that has been subjected to increasing transverse shortening during the past 10 m.y. At the southern end of the trench, where subduction has not yet started, the Puysegur Ridge has a narrow (<50 km) steep-sided cross section, and the axial strike-slip fault separates a shallow (125–625 m), flat-topped eastern crest from a deeper (400–1600 m) western crest; these characteristics indicate differential uplift during the initial stage of shortening. On the lower plate an incipient, 5.2-km-deep trench developed in conjunction with normal and reverse faults, suggesting strong interplate coupling across the trench. Northward, the ridge broadens linearly to 80 km wide, its western flank has locally collapsed, and the ridge summit has subsided, possibly by 1.5 km, suggesting that the interplate coupling decreases and that a Benioff zone is being formed. Concomitant to the northward ridge evolution, the trench deepens to 6.2 km and normal fault throws increase along its outer wall, indicating greater flexure of the downgoing plate.

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Published date: June 1995

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Local EPrints ID: 52423
URI: http://eprints.soton.ac.uk/id/eprint/52423
ISSN: 0091-7613
PURE UUID: 7b7ee8fd-b824-4463-b207-fa8a01836523

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Date deposited: 26 Jun 2008
Last modified: 15 Mar 2024 10:36

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Contributors

Author: J-Y. Collot
Author: G. Lamarche
Author: R.A. Wood
Author: J. Delteil
Author: M. Sosson
Author: J-F. Lebrun
Author: M.F. Coffin

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