Passive and active seismological study of bending-related faulting and mantle serpentinization at the Middle America trench.

Grevemeyer, Ingo, Ranero, César R., Flueh, Ernst R., Klaeschen, Dirk and Bialas, Jörg (2007) Passive and active seismological study of bending-related faulting and mantle serpentinization at the Middle America trench. Earth and Planetary Science Letters, 258 . pp. 528-542. DOI 10.1016/j.epsl.2007.04.013.

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Abstract

Water transported within the subducting oceanic lithosphere into the Earth's interior affects a wealth of subduction zone processes, including intraslab earthquakes and arc magmatism. In recent years growing evidence suggests that much of the hydration of oceanic plates occurs at the trench–ocean slope right before subduction. Here, normal faults are created while the rigid lithosphere bends into the trench. Offshore of Middle America, multi-channel seismic reflection imaging suggests that bending-related faults cut into the uppermost mantle, providing a mechanism for hydration and transformation of mantle peridotites into serpentinites. Seismic wide-angle reflection and refraction data were collected coincident with one of the seismic profiles where the faults have been imaged. Travel time inversion provides evidence that both crustal and uppermost mantle velocities are reduced with respect to the velocity structure found in mature oceanic crust away from deep-sea trenches. If mantle velocity reduction is solely produced by hydration, velocities indicate 10–15% of serpentinization in the uppermost 3 km of the mantle, where seismic data provide enough resolution. A small network of ocean bottom hydrophones, deployed for about a month, detected ∼ 3 local micro earthquakes per day. Earthquake epicentres align with fault scarps at the seafloor and continuous earthquake activity might be an important process to facilitate the percolation of seawater into the upper mantle.

Document Type: Article
Keywords: Subduction, Bending-related normal faulting, Seismic refraction, Earthquakes, Serpentinization, Global water cycle
Research affiliation: OceanRep > SFB 574 > A1
OceanRep > SFB 574 > A5
OceanRep > SFB 574
OceanRep > SFB 574 > A2
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2007.04.013
ISSN: 0012-821X
Projects: SFB574, Future Ocean
Contribution Number:
ProjectNumber
SFB 574112
Expeditions/Models/Experiments:
Date Deposited: 09 Dec 2009 11:02
Last Modified: 30 Jan 2017 12:26
URI: http://oceanrep.geomar.de/id/eprint/2304

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