Neogene Paleostress And Structural Evolution of Trinidad: Rotation, Strain Partitioning, and Strike-Slip Reactivation of an Obliquely-Colliding Thrust Belt

Author(s): Paul Mann (presenter), J.C. Hippolyte, University of Houston

Kinematic analysis of faults in Trinidad reveals three main stages of the tectonic evolution of the southeastern Caribbean–South American plate boundary. During Stage 1, folding and thrusting occurred and are truncated by a Middle Miocene unconformity. This shortening event has been related by previous workers to the initial, oblique collision of the Great Arc of the Caribbean with the passive margin of South America. We propose that Stage 1 Middle Miocene east-northeast-trending compression documented in this study initially had a more northwest–southeast direction and has been rotated in a clockwise direction during this collision. This tectonic stage resulted in clockwise rotation of structures along the southeastern Caribbean plate margin within a broad, right-lateral, strike-slip zone. During Stage 2 in the late Miocene and middle Pliocene, south-southeast-trending shortening uplifted the Central Range, formed prominent north-dipping thrusts that are bounded by oblique ramps such as the LosBajos right-lateral strike-slip fault, and formed piggy-back basins. This north-northwest–south-southeast trend of compression is compatible with coeval right-lateral shear on the El Pilar fault zone in Trinidad. We interpret this pattern of coeval and strike-slip faults of Stage 2 as the result of strain partitioning. In Stage 3 during the late Pliocene–Quaternary, east-southeast-trending compression reactivated previous thrusts as right-lateral, strike-slip faults, such as the Central Range fault. East-southeast-trending compression deactivated previous, east–west-trending, strike-slip faults such as the eastward extension of the El Pilar fault zone into Trinidad. The polyphase tectonic evolution of Trinidad occurs in the regional context of the eastward motion of the Caribbean plate with propagation of the southern Subduction-Transform Edge Propagator (STEP) fault.

Bio:

Paul Mann, University of Houston

Paul earned a BSc from the Oberlin College and a PhD from the State University of New York at Albany, both degrees in Geology.

He currently is Professor of Geology at the Dept. of Earth and Atmospheric Sciences, University of Houston, where he teaches, researches and supervises grad and undergrad students, and service to the EAS Dept. and other groups. He has also operated an oil industry-funded research group since 2005. Paul is a member of AAPG, GSA, AGU, SEG and HGS.