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Strike-slip faults mediate the rise of crustal-derived fluids and mud volcanism in the deep sea

2015; Geological Society of America; Volume: 43; Issue: 4 Linguagem: Inglês

10.1130/g36359.1

1943-2682

Christian Hensen, Florian Scholz, Marianne Nuzzo, Vasco Valadares, Eulália Gràcia, Pedro Terrinha, Volker Liebetrau, Norbert E Kaul, Sónia Silva, S. Martínez‐Loriente, Rafael Bartolomé, Elena Piñero, V. Magalhães, Mark Schmidt, Stephan M. Weise, Marina R. Cunha, Ana Hilário, Héctor Perea, Lorenzo Rovelli, Klas S Lackschewitz,

Geological and Geochemical Analysis

We report on newly discovered mud volcanoes located at ~4500 m water depth ~90 km west of the deformation front of the accretionary wedge of the Gulf of Cadiz, and thus outside of their typical geotectonic environment.Seismic data suggest that fluid flow is mediated by a >400-km-long strike-slip fault marking the transcurrent plate boundary between Africa and Eurasia.Geochemical data (Cl, B, Sr, 87 Sr/ 86 Sr, δ 18 O, δD) reveal that fluids originate in oceanic crust older than 140 Ma.On their rise to the surface, these fluids receive strong geochemical signals from recrystallization of Upper Jurassic carbonates and clay-mineral dehydration in younger terrigeneous units.At present, reports of mud volcanoes in similar deep-sea settings are rare, but given that the large area of transform-type plate boundaries has been barely investigated, such pathways of fluid discharge may provide an important, yet unappreciated link between the deeply buried oceanic crust and the deep ocean.