Subduction erosion and basal friction along the sediment-starved convergent margin off Antofagasta, Chile.

von Huene, Roland and Ranero, Cesar (2003) Subduction erosion and basal friction along the sediment-starved convergent margin off Antofagasta, Chile. Journal of Geophysical Research: Solid Earth, 108 (B2). p. 2079. DOI 10.1029/2001JB001569.

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Abstract

Subduction erosion is commonly associated with strong interplate coupling and a consequent abrasion of the upper plate. Northern Chile is an often cited example of a strongly coupled erosional margin. Its crystalline basement is inferred to form a strong upper plate, the trench axis contains little detectable sediment, and the subducting lower plate has a high‐relief horst‐graben topography. With little water‐rich sediment to reduce interplate friction, the high relief of an igneous ocean crust thrust beneath continental basement should generate high friction interplate abrasion. However, a prestack depth‐migrated seismic record images slope debris that collects in a frontal prism. This debris, including ∼30% pore fluid, fills subducting grabens and is subsequently incorporated into an ∼1.5‐km‐thick interplate reflective layer. The subduction zone thrust passes through the upper part of this layer. Interplate seismicity and taper analyses indicate basal friction at levels that are common in sedimented convergent margins. The continued growth of lower plate grabens after subduction probably accommodates upper plate material, a process that erodes the upper plate. Erosion is aided by weakening of the upper plate rock framework beneath the continental slope. This erosion undermines the upper plate and tips it seaward thereby steepening the continental slope which induces midslope gravity tectonics. Despite sediment starvation, a frontal prism constructed of remolded slope debris elevates pore pressure to reduce interplate friction. Coeval erosion and prism building control the size of the frontal prism. Processes other than high friction abrasion best explain subduction erosion along northern Chile.

Document Type: Article
Keywords: convergent margin, tectonic processes, subduction erosion
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.: 10.1029/2001JB001569
ISSN: 0148-0227
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 57443
Date Deposited: 07 Apr 2010 11:49
Last Modified: 25 Apr 2018 09:54
URI: http://oceanrep.geomar.de/id/eprint/698

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