SANTIAGO, NUBIA, Lagoven, S.A., Caracas, Venezuela

ABSTRACT: Restudy of the Sedimentary Environment of Los Jabillos Formation of Northeastern Venezuela

From the study of five sections located on the southern flank of the Interior Range, we have determined the sedimentary characteristics of Los Jabillos Formation and propose a model for its deposition. During Oligocene time there were changes in the paleoslope direction of the basin, with a predominance of southwest to northeast. The relative variations of sea level, in this part of the Western Venezuelan basin were controlled by subsidence tectonic, which was of major influence in the sedimentation of Los Jabillos Formation.

During this epoch and under these conditions, the shelf was covered by sediments from Guayana shield. There were deposits in a wave dominated delta, where the stream-mouth bars were continually reworked into a series of superimposed coastal bars. The littoral currents transported these sands sediments parallel to the coast, causing a decrease in thickness of the units both toward the east and the west.

The sandy beds (beach and marine bar), deposits on both sides of stream mouth are preserved in outcrops in Querecual, Oro, and Areo rivers. They are composed of mature quartz sandstone, with good size selection and have, therefore, good permeability. Examples of the marine bar facies have also been studied in wells in the Maturin subbasin where data were obtained from a conventional core.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.