Paul Mann1, John Weber2, Lesli J. Wood3
(1) Institute for Geophysics, University of Texas at Austin, Austin, TX
(2) Grand Valley State University, Allendale, MI
(3) The University of Texas at Austin, Austin, TX
ABSTRACT: Tectonic Framework for Trinidad and its Eastern Offshore Area
A variety of tectonic models have been proposed for the Trinidad region including an ENE-trending fold-thrust belt formed by convergence between the Lesser Antilles arc and South American continent, 2) an EW strike-slip plate boundary zone which includes ENE transpressional and WNW transtensional faults, and 3) an extensional margin in the eastern offshore region related to either gravitational loading by Orinoco River deltaic sediments and/or tectonic stresses produced by east-west right-lateral shear. In this presentation we summarize both geologic and GPS-based geodetic data at 8 sites in the Trinidad region supporting the interpretation of an EW strike-slip plate boundary zone in the onshore part of Trinidad and use bathymetric, seismic, and well data to extend this strike-slip style into the more complex, eastern offshore area. GPS data indicate that the rate of motion in Trinidad is 18±3 mm/yr in a direction of 085±2 east of north. Geologic studies onshore and in the Gulf of Paria support the idea that fault structures are sensitive to this regional interplate slip direction direction with more northeasterly segments exhibiting transpressional structures and more northwesterly segments exhibting transtensional structures including a pull-apart basin in the Gulf of Paria. A transpressional style of deformation can be traced along the El Pilar and Central Range faults into the eastern offshore area. Darien Ridge forms an abrupt boundary between the transpressional province to the north and down-to-the-northeast normal faults to the south that are driven by gravitation loading and/or tectonic stresses related to strike-slip motion.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado