(1) Harvard University, Cambridge, MA
Abstract: Mesozoic-Cenozoic Structural Evolution of The Northern Eastern Cordillera Fold Belt, Colombia
The detailed structural analysis of field geologic maps, remote sensing images and a closely spaced grid of industry 2-D seismic reflection data allowed the northern portion of the Eastern Cordillera of Colombia to be divided into seven major structural domains. The interpretation of the stratigraphic and structural relationships between Upper Jurassic syn-rift type deposits and Lower Cretaceous post-rift sedimtary rocks, allowed to interpred these domains as the result of inversion of Jurassic rift basins and half grabens during the Tertiary.
A more detailed geologic analysis on the eastern margin of the northern portion of the Eastern Cordillera of Colombia lend new insight into the extent, style, and sequence of thrusts, and timing of deformation within this fold belt. At least three major deformation events are invoked for the structures along the eastern margin of the northen portion of the Eastern Cordillera. A first event is interpreted to have occurred during the Oligocene, forming a southeast-vergent imbricate fan. This imbricate fan was eroded and covered by middle-late Oligocene deposits forming a major angular unconformity. A subsequent contractile event in Miocene-Pliocene time reactivated pre-existing thrust faults and created new ones that folded those formed during the earlier event. Thrust faults produced in this later shortening event offset the angular unconformity. A more recent tectonic event has folded all the structures from the previous events. The thin-skinned thrust faults of the eastern margin of the Eastern Cordillera can be linked to the inversion of Jurassic-early Cretaceous age extensional faults since the Oligocene, which are still active.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana