VILLAMIL, T., University of Colorado, Boulder, CO, P. RESTREPO, University of Arizona, Tuscon, AZ, R. RATLIFF, S. WU, R. KLIGFIELD, P. GEISER, CogniSeis Development, Boulder, CO
The Bogota fold belt of the Eastern Cordillera, Colombia has long been considered a relatively simple zone of Tertiary-aged folding. To a large degree this picture is due to the presence of a monotonous sequence of turbidites which contains very few distinct formation boundaries useful for delineating the structural geometry. However, new surface mapping together with biostratigraphic and sequence stratigraphic zonation have been used to define a complex thrust system involving southeast vergent imbricate and duplex structures. Biozone and facies boundaries are recognizable throughout the mapped area and provide a high resolution stratigraphic template for structural analysis. The thrustbelt architecture is illustrated by a 17 km long balanced cross section which has been constructed sing kinematic fault bend and fault propagation fold models. The use of balanced section construction techniques has in turn allowed further refinement of the stratigraphic model and facies analysis in the palinspastic restoration. The cross section constrains an overall breakforward sequence of thrust initiation with a lower detachment in shales at the base of the Cretaceous Caqueza Group. There are a minimum of 16 major ramps through the Cretaceous section and an irregularly developed upper detachment near the top of the Caqueza Group. The deformation has resulted in a minimum of 13 km of horizontal shortening in this portion of the Eastern Cordillera.
AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.