Quaternary tectonics and present stress tensor of the inverted northern Falcon Basin, northwestern Venezuela

The Tertiary Falcon Basin in northwestern Venezuela has a privileged position in the geodynamic puzzle of northwestern South America, occurring in a region where several major plates (Caribbean, South America and Nazca) and minor lithospheric blocks (Maracaibo. Bonaire and Western Colombia) are interacting. A combination of good exposures due to aridity and a near-continuous sedimentary record in a now inverted basin helps to unravel the Neogene and Quaternary geodynamic evolution of this region. A neotectonic and microtectonic investigation of the Plio-Quaternary sedimentary rocks of the northern Falcon Basin reveals that this region is subject to a compressive to transpressive regime at present. This regime is characterized by a NNW-SSE oriented maximum horizontal stress. and a ENE-WSW trending intermediate: (or minimum) horizontal stress. as is confirmed by focal mechanism solutions. This stress field is in agreement both with the NNE-directed extrusion of the Maracaibo and Bonaire blocks in Western Venezuela, where the Falcon Basin is located, and present-day transpression along the Caribbean-South America plate boundary zone. (C) 2001 Elsevier Science Ltd. All rights reserved.