Deepwater fold-and-thrust belt along New Caledonia's western margin: relation to post-obduction vertical motions
Type | Article | ||||||||||||
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Date | 2017-10 | ||||||||||||
Language | English | ||||||||||||
Author(s) | Collot Julien1, Patriat Martin![]() |
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Affiliation(s) | 1 : DIMENC, Serv Geol Nouvelle Caledonie, Noumea, New Caledonia. 2 : IFREMER, Noumea, New Caledonia. 3 : ZoNeCo Res Program, ADECAL Technopole, Noumea, New Caledonia. 4 : Novas Oil & Gas Consulting Ltd, Slough, Berks, England. 5 : CNRS, Geoazur, IRD, UNSA,OCA,UMR 7329, Noumea, New Caledonia. 6 : Univ Orleans, ISTO, Orleans, France. 7 : Univ Nouvelle Caledonie, LIVE, Noumea, New Caledonia. |
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Source | Tectonics (0278-7407) (Amer Geophysical Union), 2017-10 , Vol. 36 , N. 10 , P. 2108-2122 | ||||||||||||
DOI | 10.1002/2017TC004542 | ||||||||||||
WOS© Times Cited | 7 | ||||||||||||
Keyword(s) | deepwater fold-and-thrust belt, obduction, isostasy | ||||||||||||
Abstract | Classically, deepwater fold-and-thrust belts are classified in two main types, depending if they result from near- or far-field stresses and the understanding of their driving and triggering mechanism is poorly known. We present a geophysical dataset off the western margin of New Caledonia (SW Pacific) that reveals deformed structures of a deepwater fold-and-thrust belt that we interpret as a near-field gravity-driven system, which is not located at a rifted passive margin. The main factor triggering deformation is inferred to be oversteepening of the margin slope by post-obduction isostatic rebound. Onshore erosion of abnormally-dense obducted material, combined with sediment loading in the adjacent basin, has induced vertical motions that have caused oversteepening of the margin. Detailed morpho-bathymetric, seismic stratigraphic and structural analysis reveals that the fold-and-thrust belt extends 200 km along the margin, and 50 km into the New Caledonia Trough. Deformation is rooted at depths greater than 5 km beneath the seafloor, affects an area of 3500 km2, and involves a sediment volume of approximately 13 000 km3. This deformed belt is organized into an imbricate fan system of faults, and one out-of-sequence thrust fault affects the seabed. The thrust faults are deeply rooted in the basin along a low-angle floor thrust and connected to New Caledonia Island along a major detachment. This study not only provides a better knowledge of the New Caledonia margin, but also provides new insight into the mechanisms that trigger deepwater fold-and-thrust belts. |
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