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Island arc response to shallow subduction of the Cocos Ridge, Costa Rica

Radim A. Kolarsky, Paul Mann and Walter Montero
Island arc response to shallow subduction of the Cocos Ridge, Costa Rica (in Geologic and tectonic development of the Caribbean Plate boundary in southern Central America, Paul Mann (editor))
Special Paper - Geological Society of America (1995) 295: 235-262

Abstract

Shallow subduction of the Cocos Ridge beneath the Costa Rican island arc results in six major tectonic effects. These effects include a volcanic gap in the Costa Rican volcanic arc chain, a shallowing of the dip of the subducted Cocos plate beneath Costa Rica, forearc indentation of the Pacific margin of Costa Rica, structural inversion of forearc (Terraba) and backarc (Limon) basins, arching of on- and offshore acoustic basement in a direction parallel to plate convergence between Costa Rica and the Cocos plate, and a radial stress pattern around the underthrust area of the Cocos Ridge as inferred from earthquake and geologic indicators. Structures formed in forearc basin sedimentary and volcanic rocks of the Terraba belt above the subducted Cocos Ridge include major reverse faults that consistently place older lithologic units over younger lithologic units. One of these faults, the Ballena-Celmira fault zone, forms a prominent linear contact between Quaternary alluvium of the Pacific coastal plain and the Terraba belt. Bedding plane and fault data in the Terraba belt constrain a maximum shortening direction of N30-34 degrees E for the central and eastern Terraba belt. This direction of maximum shortening corresponds closely to the N35 degrees E direction of maximum shortening of Corrigan et al. (1990) from Plio-Pleistocene rocks of the outer forearc in the Burica/Osa area to the south and southeast of the Terraba belt. Assuming that the predicted plate convergence direction (N32 degrees E) and the direction of maximum shortening in the forearc subparallel, thrusting and tilting in the forearc of westernmost Panama and eastern and central Costa Rica is interpreted as the result of regional northeast-southwest-oriented maximum compressive stresses exerted by post-Miocene shallow subduction of the Cocos Ridge.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 295
Title: Island arc response to shallow subduction of the Cocos Ridge, Costa Rica
Title: Geologic and tectonic development of the Caribbean Plate boundary in southern Central America
Author(s): Kolarsky, Radim A.Mann, PaulMontero, Walter
Author(s): Mann, Pauleditor
Affiliation: University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States
Affiliation: University of Texas at Austin, Institute for Geophysics, Austin, TX, United States
Pages: 235-262
Published: 1995
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 0-8237-2295-0
References: 71
Accession Number: 1995-028243
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. cols., 1 table, geol. sketch maps
N09°43'41" - N13°17'08", W91°23'35" - W86°05'26"
Secondary Affiliation: Universidad de Costa Rica, CRI, Costa Rica
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199510
Program Name: DSDPDeep Sea Drilling Project
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