THERMOCHRONOLOGIC CONSTRAINTS ON MIOCENE TRANSPRESSIONAL EXHUMATION ALONG THE CENTRAL RANGE FAULT ZONE, TRINIDAD

The Central Range fault zone records transpressional kinematics and accommodates most of the slip between the Caribbean and South American Plates in Trinidad. Global Positioning System data and paleoseismic work suggest this zone is active today and has been active for at least the past several thousand years. The modern fault zone overprints Miocene contraction, therefore the strain recorded in the Central Range fault zone is the sum of both Miocene and more recent events. Thermochronology data from Eocene and Oligocene sandstones in the Central Range were collected to constrain the thermal history associated with exhumation driven by transpression. Previously collected apatite fission-track (AFT) data yielded mixed results. AFT cooling ages range from 30 to 15 Ma, however most sites fail the chi squared tests suggesting multiple age populations may be present. Pooled AFT ages tentatively suggest that rocks presently at the surface were exhumed through part of the apatite fission-track partial annealing zone in response to Miocene contraction. Unfortunately, apatite grains >50 microns in diameter are not present, therefore we were unable to collect apatite (U-Th)/He data. In this contribution we present the results of (U-Th)/He analysis on subhedral, inclusion-free zircons collected from eight samples. These data provide insight into the Miocene tectonic history of the Central Range and constrain the total amount of exhumation due to Miocene to recent deformation.