Along-strike Crustal Thickness Variations of the Subducting Caribbean Plate Produces Two Distinctive Styles of Thrusting in the Offshore South Caribbean Deformed Belt, Colombia
Rocio Bernal-Olaya, Javier Sanchez, Paul Mann, Michael Murphy, 2015. "Along-strike Crustal Thickness Variations of the Subducting Caribbean Plate Produces Two Distinctive Styles of Thrusting in the Offshore South Caribbean Deformed Belt, Colombia", Petroleum Geology and Potential of the Colombian Caribbean Margin, Claudio Bartolini, Paul Mann
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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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AAPG Memoir 108 is the first international book published on the petroleum geology and hydrocarbon potential of Colombia’s Caribbean Margin. Tis volume consists of 27 multidisciplinary papers that include a wide range of geological and geophysical topics, such as geochemistry and petroleum systems, earthquake seismology and tomography, seismic stratigraphy and sedimentology, oil and gas exploration plays, carbonate and siliciclastic petrology, basement studies, regional tectonics and structural geology, fold belt structural analyses, potential methods, and studies of deep-sea sedimentation on the Magdalena fan. This highly valuable and innovative piece of information is critical for geoscientists in the petroleum industry, research institutions, and academia. Do not miss the opportunity to learn about the extremely complex but fascinating geology of Colombia's Caribbean Margin and its important hydrocarbon potential.