NEOTECTONIC KINEMATICS (GPS) VS. GEOLOGIC KINEMATICS OF THE CENTRAL RANGE FAULT SYSTEM, SOUTH AMERICAN-CARIBBEAN PLATE BOUNDARY, TRINIDAD

The Central Range fault system of Trinidad is part of an active zone of deformation within the South American-Caribbean plate boundary. This dextral fault system strikes SW-NE across central Trinidad, and accommodates a portion of the total movement along the transpressional plate boundary. It is uncertain whether most of the deformation recorded in the Central Range is due to recent dextral movement or from a Miocene contraction. Recent studies using GPS show total relative plate motion of ~20 mm/yr. The Central Range fault accounts for ~12 mm/yr of the total ~20 mm/yr between the South American-Caribbean plates. The GPS data also yields a current angle of oblique convergence of ~20°. Comparison of GPS data to geologic data gives some insight into the consistency of plate motion along the Central Range fault system through time.

Geologic data characterizes the kinematics of the tectonic-scale deformation occurring over long-term time scales. A fold analysis using shortening values, limb dips, and hinge orientation based on cross sections along the Central Range constrain the angle of oblique convergence over a longer time frame. Paleomagnetic data from the Tamana Formation documents the rotational component of deformation along this fault zone since the Miocene time. The angle of convergence from the fold analysis, combined with paleomagnetic data, make it possible to estimate the total amount of displacement across the Central Range. Determination of the total displacement along the Central Range fault may give some indication as to whether modern plate motion rates determined by GPS could have accommodated the total movement since the Miocene time, or whether rates of plate motion have varied along the South American-Caribbean plate boundary through time.