RODRIGUES, J., Universidad Central de Venezuela, Caracas, Venezuela, and Maraven, S.A., E. BUENO, Maraven, S.A., D. Loureiro, Universidad Central de Venezuela, Caracas, Venezuela, and M. OSTOS, Universidad Central de Venezuela, Caracas, Venezuela, and Fairfield Industries de Venezuela

ABSTRACT: Tectonic Significance of the Valera Fault Zone, Northwestern Venezuela

A detailed structural study was performed at the southern end of the north-south to north-northwest Valera fault zone. The area is particularly interesting, since it lies close to the triple point were the Maracaibo and Lara blocks meet the South American plate.

The fault zone is associated with an anticlinorium with the following structural features: (a) conic folds with hinges oriented N26-35E; (b) a main, left-lateral, north-northwest to north-south fault population; (c) a secondary set of dextral west-northwest faults; and (d) two secondary sets of left-lateral northwest and northeast faults. The structural pattern and the dynamic analysis of the faults, which indicates a N 46-50 W shortening, is compatible with the spatial arrangement of structures associated with a north-south to north-northwest sinistral strike-slip fault.

A regional interpretation based on seismic sections tied to wells suggests a continuos and complex structural evolution, including: (a) early Eocene northwesterly trending normal faulting, at the forebulge developed during the emplacement of the Lara nappes; (b) Early Neogene NW reverse faulting and inversion of early normal faults, at the transpressive zone that bounded the Maracaibo and Lara blocks; (c) Late Neogene development of the sinistral Valera fault zone to accommodate the tangential component of the relative movement between the two blocks.

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