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Along-strike Crustal Thickness Variations of the Subducting Caribbean Plate Produces Two Distinctive Styles of Thrusting in the Offshore South Caribbean Deformed Belt, Colombia

By
Rocio Bernal-Olaya
Rocio Bernal-Olaya
Department of Earth and Atmospheric Sciences, University of Houston, 312 Science and Research Bldg. 1, Houston, Texas 77204, U.S.A
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Javier Sanchez
Javier Sanchez
Department of Earth and Atmospheric Sciences, University of Houston, 312 Science and Research Bldg. 1, Houston, Texas 77204, U.S.A
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Paul Mann
Paul Mann
Department of Earth and Atmospheric Sciences, University of Houston, 312 Science and Research Bldg. 1, Houston, Texas 77204, U.S.A
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Michael Murphy
Michael Murphy
Department of Earth and Atmospheric Sciences, University of Houston, 312 Science and Research Bldg. 1, Houston, Texas 77204, U.S.A
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Published:
January 01, 2015

Abstract

The offshore South Caribbean deformed belt (SCDB) is a 100-km-wide (62 mi), late Cenozoic sedimentary accretionary prism formed where the Caribbean plate is obliquely subducted beneath northern South America. Progradation of deltaic deposits of the 1500-km-long (932 mi) Magdalena River over the SCDB and tectonic deformation of the deltaic sedimentary rocks has created one of the youngest (last 10 Ma) and thickest (5–18 km [3–5 mi]) accretionary prisms in the world. We use three types of data (deep-penetration, seismic-reflection profiles, gravity modeling collinear with the seismic lines, and structural restorations) to describe the late Miocene to Recent thrust kinematics of the 10- to 18-km-thick (6.2–11.1 mi) SCDB formed above the subducting Caribbean Oceanic Plateau whose crust varies in thickness from 17 km (10.6 mi) in the southern part of the 180-km-long (111 mi) study area to 8 km (4.9 mi) in the north. In the southern area of thicker subducted plateau crust, the structural style is characterized by Neogene growth strata defining a major thrusted sequence that is backthrust in a landward direction, deformed by reactivation of preexisting faults as out-of-sequence thrust (OOST) faults, common shale diapirism, and active, margin-parallel strike-slip faults that accommodate the oblique-slip component of subduction. In the northern area of thinner oceanic crust (6–8 km [3.7–4.9 mi]), the structural style includes seaward-verging, imbricated thrust fans with less prominent backthrusting and strike-slip faulting, and more prominent shale diapirism. Proposed controls for the observed structural differences between the northern and southern areas include (1) more buoyancy of the subducted plate in the southern area due to its greater crustal thickness, and (2) the presence of more overpressured and ductile deformed shale layers with associated shale diapirs in the north.

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Contents

AAPG Memoir

Petroleum Geology and Potential of the Colombian Caribbean Margin

Claudio Bartolini
Claudio Bartolini
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Paul Mann
Paul Mann
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American Association of Petroleum Geologists
Volume
108
ISBN electronic:
9781629812724
Publication date:
January 01, 2015

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