Tectonic structure of the convergent Pacific margin offshore Costa Rica from multichannel seismic reflection data.

Hinz, K., von Huene, Roland and Ranero, Cesar and PACOMAR Working Group (1996) Tectonic structure of the convergent Pacific margin offshore Costa Rica from multichannel seismic reflection data. Open Access Tectonics, 15 (1). pp. 54-66. DOI 10.1029/95TC02355.

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Abstract

The Middle America Trench between the Cocos Ridge and a well-studied corridor off the Nicoya Peninsula has a more varied morphology and structure than previously reported. The morphological positive features on the lower plate significantly affect the upper plate structure. The Cocos Ridge has uplifted the margin opposite the Osa Peninsula. Northwest of Cocos Ridge, numerous seamounts on the oceanic crust sculptured the margin as they subducted. A seamount and a huge slump in the trench axis that currently block lateral sediment transport affect the sediment currently accreted and subducted. The greater portion of the trench sediment is subducted beneath a lower slope accretionary mass. Beneath the middle and upper slope is a margin wedge consisting of a high-velocity rock with few internal reflections. Its upper surface has a nondirectional random relief commonly 500 m high in the middle slope area. Overlying this surface is a low-velocity cover of slope sediment which shows little transgressive stratigraphy and can be traced landward into an inferred Eocene section beneath the shelf. The shelf basement is composed of Nicoya complex (ophiolite) with the same acoustic velocity, similar structure, and no apparent dividing geologic boundary with the margin wedge. We favor a seaward continuation of the Nicoya complex to the middle slope and emphasize the evidence for a non-steady state Tertiary tectonic history.

Document Type: Article
Keywords: Tectonic structure; Pacific margin, Costa Rica, Cocos Ridge; RV Sonne, SO76; SO81
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/95TC02355
ISSN: 0278-7407
Projects: PACOMAR
Expeditions/Models/Experiments:
Date Deposited: 16 Feb 2016 11:27
Last Modified: 12 May 2017 11:25
URI: http://oceanrep.geomar.de/id/eprint/31363

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