Continuous exhumation of mantle-derived rocks at the Southwest Indian Ridge for 11 million years

Type Article
Date 2013-04
Language English
Author(s) Sauter Daniel1, Cannat Mathilde2, Roumejon Stephane2, Andreani Muriel3, 4, Birot Dominique5, Bronner Adrien1, Brunelli Daniele6, Carlut Julie2, Delacour Adelie6, Guyader VivienORCID5, Macleod Christopher J.8, Manatschal Gianreto1, Mendel Veronique1, Menez Benedicte2, Pasini Valerio2, 6, Ruellan Etienne9, Searle Roger10
Affiliation(s) 1 : Univ Strasbourg, Inst Phys Globe Strasbourg, UMR CNRS 7516, F-67084 Strasbourg, France.
2 : Univ Paris Diderot, Inst Phys Globe Paris, Equipe Geosci Marines, Sorbonne Paris Cite,UMR CNRS 7154, F-75005 Paris, France.
3 : ENS, Lab Sci Terre, F-69622 Villeurbanne, France.
4 : Univ Lyon, F-69622 Villeurbanne, France.
5 : IFREMER, Ctr Brest, Dept Geosci Marines, Lab Geochim Metallogenie, F-29280 Plouzane, France.
6 : Univ Modena & Reggio Emilia, Dipartimento Sci Terra, I-41100 Modena, Italy.
7 : Univ St Etienne, Dept Geol, UMR CNRS 6524, F-42023 St Etienne 2, France.
8 : Cardiff Univ, Sch Earth & Ocean Sci, Cardiff CF10 3YE, S Glam, Wales.
9 : OCA UNS GeoAzur, UMR CNRS 7329, F-06560 Valbonne, France.
10 : Univ Durham, Dept Earth Sci, Durham DH1 3LE, England.
Source Nature Geoscience (1752-0894) (Nature Publishing Group), 2013-04 , Vol. 6 , N. 4 , P. 314-320
DOI 10.1038/NGEO1771
WOS© Times Cited 113
Abstract The global mid-ocean ridge system, where tectonic plates diverge, is traditionally thought of as the largest single volcanic feature on the Earth. Yet, wide expanses of smooth sea floor in the easternmost part of the Southwest Indian Ridge in the Indian Ocean lacks the hummocky morphology that is typical for submarine volcanism. At other slow-spreading ridges, the sea floor can extend by faulting the existing lithosphere, along only one side of the ridge axis. However, the smooth sea floor in the easternmost Southwest Indian Ridge also lacks the corrugated texture created by such faulting. Instead, the sea floor is smooth on both sides of the ridge axis and is thought to be composed of altered mantle-derived rocks. Here we use side-scan sonar to image the sea floor and dredge samples to analyse the composition of two sections of the Southwest Indian Ridge, between 62 degrees 05'E and 64 degrees 40'E, where the sea floor formed over the past 11 million years. We show that the smooth floor is almost entirely composed of seawater-altered mantle-derived rocks that were brought to the surface by large detachment faults on both sides of the ridge axis. Faulting accommodates almost 100% of plate divergence and the detachment faults have repeatedly flipped polarity. We suggest that this tectonic process could also explain the exhumation of mantle-derived rocks at the magma-poor margins of rifted continents.
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Sauter Daniel, Cannat Mathilde, Roumejon Stephane, Andreani Muriel, Birot Dominique, Bronner Adrien, Brunelli Daniele, Carlut Julie, Delacour Adelie, Guyader Vivien, Macleod Christopher J., Manatschal Gianreto, Mendel Veronique, Menez Benedicte, Pasini Valerio, Ruellan Etienne, Searle Roger (2013). Continuous exhumation of mantle-derived rocks at the Southwest Indian Ridge for 11 million years. Nature Geoscience, 6(4), 314-320. Publisher's official version : https://doi.org/10.1038/NGEO1771 , Open Access version : https://archimer.ifremer.fr/doc/00136/24771/