Geological Studies in Eastern Venezuela and Trinidad: From Cretaceous Passive Margin to Neogene Transpressional Thrust Belt

ALGAR, S. T., J. E. ERIKSON, and J. L. PINDELL, Dartmouth College, Hanover, NH

Sedimentological and structural analyses of Trinidad's Northern and Central ranges and Venezuela's Serrania del Interior have led to new interpretations of northeastern South America's tectonic evolution within the Southern Caribbean Plate Boundary Zone. Medial(?) Jurassic through early Cenozoic passive margin sediments make up the majority of these areas and were deposited somewhat to the WNW (between 80 and 130 km for Northern Range of Trinidad) of their present positions prior to structural shortening. Neogene southeastward displacement of Jurassic-Cretaceous passive slope and rise sediments (Northern Range) drove propogation of thrusts southward into the Serrania and Central ranges. Displacements were driven by migration of the Caribbean Plate relative to South America. Thus, the errania and Central ranges are the western hemisphere's only exposed Mesozoic-Cenozoic passive Atlantic margin stratigraphic section. As such, they provide a Cretaceous-Paleogene record of passive margin sedimentation at a thermally subsiding margin where the complicating effects of tectonism are absent. This makes these sections especially suited for studies of eustatic sea level behavior. Preliminary assessments

are shown which suggest that sea level changes for Cretaceous to Paleogene time are not as pronounced as the frequent large and rapid sea level falls and rises that are promoted by some.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)