AVE LALLEMANT, HANS G., VIRGINIA B. SISSON, and JAMES E. WRIGHT, Rice University, Department of Geology and Geophysics, Houston, TX
ABSTRACT: Structure of the Cordillera de la Costa Belt, North-Central Venezuela: Implications for Plate Tectonic Models
Preliminary results of an on-going study of the Cordillera de la Costa belt between Puerto Cabello and Choroni, north-central Venezuela, indicate that the deformational history is far more complicated than expected from simple plate-tectonic models. The Cordillera de la Costa belt consists of oceanic rocks (e.g., serpentinites, amphibilites, with lenses of eclogite and blueschist) intimately intermixed with metamorphosed continental-margin deposits (e.g., mica and graphite schist, quartzite, marble). Locally, large granitic (basement?) complexes of Lower Paleozoic age are included as well. In late Cretaceous time, the entire belt was involved in four synmetamorphic deformations phases (D1a to D1d); the first (D1a) occurred at depths of at 35 to 40 km and the later ones at successively shallower depths. This deformation occurred in a subduction zone, related to right-oblique convergence of the Farallon and Atlantic plates. The most penetrative structures resulted from (all in present coordinates) north-south contraction and east-west dextral simple shear (D1b). During an Early Tertiary(?) event (D2), the belt was emplaced southward onto the South American continental margin. Subsequent deformational structures (D3) resulted in cross folds and faults (with small pull-apart basins) which are consistent with the eastward passage of the Caribbean past the South American plate.
AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.