173 Geophysics/Tectonophysics/Seismology (Posters)

BLOCK ROTATION IN THE CENTRAL RANGE FAULT SYSTEM, CARIBBEAN-SOUTH AMERICAN PLATE BOUNDARY, TRINIDAD

Paper number: 173-2
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Trinidad, an island off the northeast coast of Venezuela is located on the Caribbean-South American plate boundary. The Central Range fault system is the active dextral fault system in the center of the island which is accommodating most of the Caribbean-South American relative motion. Previous studies using GPS data show the Caribbean plate moves eastward 20 mm/yr with respect to the South American plate. The Central Range fault system is accommodating 12 ± 3 mm/yr of this movement. The folding and faulting in the Central Range can be accounted for by Miocene events and/or recent deformation. Paleomagnetic data is used to constrain the amount of block rotation in the Central Range since the Miocene. An understanding of the total amount of strain may give insight into how much deformation is due to neotectonic activity vs. Miocene contraction.

Paleomagnetic samples were collected from 22 sites across the Central Range from the Tamana and Pointe-a-Pierre formations. Due to poor outcrop most sites were collected in quarries where continuous stratigraphic sections were clearly visible. Five to ten cores were collected at each site and were analyzed using the alternating field demagnetization process. In most samples demagnetization revealed a single magnetization component. The samples have a weak magnetization signal, on the order of 10-4 mA/m. Initial results suggest a significant amount of vertical axis block rotation in the Central Range. Samples were collected to perform a fold test from the Tamana formation, and samples were collected from the Chaudiere formation to perform the conglomerate test. Results of these tests should constrain the age of magnetization.