Extreme mantle uplift and exhumation along a transpressive transform fault

Type Article
Date 2016-08
Language English
Author(s) Maia Marcia1, Sichel Susanna2, Briais Anne3, Brunelli Daniele4, 5, Ligi Marco5, Ferreira Nicolas1, Campos Thomas6, Mougel Berengere1, 7, Brehme Isa2, Hemond Christophe1, Motoki Akihisa8, Moura Denise9, Scalabrin CarlaORCID10, Pessanha Ivo11, Alves Eliane2, Ayres Arthur2, Oliveira Pedro2
Affiliation(s) 1 : Univ Bretagne Occidentale, CNRS, IUEM, Lab Domaines Ocean, Rue Dumont dUrville, F-29280 Plouzane, France.
2 : Univ Fed Fluminense, LAGEMAR, Ave Gal Milton Tavares Souza S-N, BR-24210340 Niteroi, RJ, Brazil.
3 : Univ Toulouse, GET, Ave Edouard Belin, F-31400 Toulouse, France.
4 : Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol, Via Campi 103, I-41125 Modena, Italy.
5 : CNR, Geol Marina, ISMAR, Via Gobetti 101, I-40129 Bologna, Italy.
6 : Univ Fed Rio Grande do Norte, Dept Geol, Cidade Univ Lagoa Nova,CP 1639, BR-59072700 Natal, RN, Brazil.
7 : Inst Phys Globe Paris, 1 Rue Jussieu, F-75005 Paris, France.
8 : Univ Estado Rio de Janeiro, Ctr Tecnol & Ciencias, Inst Geociencias, Rua Sao Francisco, BR-20550013 Rio De Janeiro, Brazil.
9 : Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, BR-05508090 Sao Paulo, Brazil.
10 : IFREMER, Lab Acoust, Technopole Iroise, F-29280 Plouzane, France.
11 : Brazilian Geol Survey, CPRM, Ave Pasteur 404, BR-22290255 Rio De Janeiro, Brazil.
Source Nature Geoscience (1752-0894) (Nature Publishing Group), 2016-08 , Vol. 9 , N. 8 , P. 619-624
DOI 10.1038/NGEO2759
WOS© Times Cited 55
Abstract Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults1, 2, 3, 4, and, along transforms, by transtension due to changes in ridge/transform geometry5, 6. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic7, 8. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10 million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at ~11 million years ago5 initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly9 is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.
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Maia Marcia, Sichel Susanna, Briais Anne, Brunelli Daniele, Ligi Marco, Ferreira Nicolas, Campos Thomas, Mougel Berengere, Brehme Isa, Hemond Christophe, Motoki Akihisa, Moura Denise, Scalabrin Carla, Pessanha Ivo, Alves Eliane, Ayres Arthur, Oliveira Pedro (2016). Extreme mantle uplift and exhumation along a transpressive transform fault. Nature Geoscience, 9(8), 619-624. Publisher's official version : https://doi.org/10.1038/NGEO2759 , Open Access version : https://archimer.ifremer.fr/doc/00345/45603/