Serpentinization in the trench-outer rise region offshore of Nicaragua: constraints from seismic refraction and wide-angle data.

Ivandic, Monika, Grevemeyer, Ingo, Bialas, Jörg and Petersen, C. Jörg (2010) Serpentinization in the trench-outer rise region offshore of Nicaragua: constraints from seismic refraction and wide-angle data. Open Access Geophysical Journal International, 180 . pp. 1253-1264. DOI 10.1111/j.1365-246X.2009.04474.x.

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Abstract

Recent seismic evidence suggested that most oceanic plate hydration is associated with trench-outer rise faulting prior to subduction. Hydration at trenches may have a significant impact on the subduction zone water cycle. Previous seismic experiments conducted to the northwest of Nicoya Peninsula, Northern Costa Rica, have shown that the subducting Cocos lithosphere is pervasively altered, which was interpreted to be due to both hydration (serpentinization) and fracturing of the crustal and upper-mantle rocks. New seismic wide-angle reflection and refraction data were collected along two profiles, running parallel to the Middle American trench axis offshore of central Nicaragua, revealing lateral changes of the seismic properties of the subducting lithosphere. Seismic structure along both profiles is characterized by low velocities both in the crust and upper mantle. Velocities in the uppermost mantle are found to be in the range 7.3–7.5 km s−1; thus are 8–10 per cent lower than velocities typical for unaltered peridotites and hence confirm the assumption that serpentinization is a common process at the trench-outer rise area offshore of Nicaragua. In addition, a prominent velocity anomaly occurred within the crust beneath two seamounts. Here, velocity reduction may indicate increased porosity and perhaps permeability, supporting the idea that seamounts serve as sites for water percolation and circulation.

Document Type: Article
Keywords: hydrology, mantle processes, earthquake dynamics, seismic tomography, Subduction
Research affiliation: OceanRep > SFB 574 > A5
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1365-246X.2009.04474.x
ISSN: 0956-540X
Projects: Future Ocean, SFB574
Contribution Number:
ProjectNumber
SFB 574177
Expeditions/Models/Experiments:
Date Deposited: 09 Mar 2010 14:41
Last Modified: 13 Jul 2018 11:19
URI: http://oceanrep.geomar.de/id/eprint/3304

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