Geophysical evidence for alteration of the crust and mantle of the Nazca Plate during bending at the north Chile trench.

Ranero, César R. and Sallarès, V. (2004) Geophysical evidence for alteration of the crust and mantle of the Nazca Plate during bending at the north Chile trench. Geology, 32 (7). pp. 549-552. DOI 10.1130/G20379.1.

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Abstract

Water transported in subducting oceanic plates plays a key role in a number of phenomena, including intraslab seismicity and arc magmatism. However, the locus of plate hydration and water distribution in crust and mantle of plates entering subduction zones is debated. We present evidence for anomalously low seismic velocities and densities of the crust and upper mantle of the Nazca plate at the north Chile trench. Crustal seismic velocities at the trench are lower than velocities of mature fast-spreading crust and even lower than velocities of highly extended slow-spreading crust. In addition, the Nazca plate at the north Chile trench may contain an ∼20-km-thick upper-mantle layer with ∼17% serpentine, which implies ∼2.5 wt% water. These results document pervasive rock alteration by water percolation linked to bending-related extensional faulting.

Document Type: Article
Keywords: subduction zones, bend faulting, crust hydration, serpentinization
Research affiliation: OceanRep > SFB 574 > A1
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1130/G20379.1
ISSN: 0091-7613
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 57458
Expeditions/Models/Experiments:
Date Deposited: 10 Feb 2010 15:32
Last Modified: 04 Aug 2017 07:09
URI: http://oceanrep.geomar.de/id/eprint/4400

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