Basement control on sand distribution in the Hamaca area of the Orinoco Belt

The interpretation of aeromagnetic and seismic data in the Hamaca area of the Orinoco Belt helped to determine the basement topographic control of the sedimentation in the Hamaca area. The Cretaceous thin wedge preserved in the northwestern part of the area had a very limited effect on the deposition of sediments. Two different basement grains were interpreted from the aeromagnetic data. The contact between these two basement typed precluded the existence of a differential erosional zone along it, which exerted control on the drainage pattern of the tertiary sedimentation. Focally, fault scarps and monaduocks affected sand deposition. Regional mapping of the lower tertiary sands correlates with the basement features. The integrated regional interpretation of geophysical and geological data allowed the delineation of passive and active basement structures and their effect on the tertiary sand-shale distribution.