Abstract: Structural Development and Tectonic History of the Venezuelan Andean Ranges and Associated Basins: A Reconnaissance Study Using Thermal History Data

Michael C. Daly, Kerry A. Hegarty, Ian R. Duddy, Paul F. Green

Thermal history data from sixteen AFTA^TM (Apatite Fission Track Analysis) and twelve VR (vitrinite reflectance) samples have been used to constrain the development of the Falcon basin (Venezuela) and its perimeter, a structurally complex area subject to a series of deformational events. Following Jurassic rifting, the Yucatan region migrated northward followed by Late Cretaceous/Paleocene collision with the Caribbean arc resulting in the emplacement southward of a series of flysch thrust sheets. Later compressional deformation commencing in the Miocene and continuing to the present day has resulted in the inversion of the rift basins into a major fold belt.

These results have provided new control on the development of the region, in particular on the temporal relationships between thrusting and basin inversion and on the potential for hydrocarbon occurrences in the region.

AFTA samples from the Paraguana peninsula indicate cooling commenced about 60 to 50 Ma, recording the initial collision of the Caribbean arc with South America. Since that time the Paraguana peninsula has experienced no further significant burial and remained an elevated horst block to the present. Coeval with elevation of Paraguana, the region now represented by the Barbacoas and Barquisimeto Andes, to the south of the Falcon basin, experienced deep burial. This burial occurred in the foredeep basin developed to the south of the colliding arc, and was achieved by both foredeep sedimentation and the emplacement of the Lara and Cotiere nappe complexes. Both Andean areas experienced a more recent episode of uplift and cooling, post-nappe emplacement, commencing some time between 50 and 0 Ma (Middle Eocene to Early Oligocene). This new information has important implications for the involvement of a proto-Andean chain during the Paleocene-Eocene evolution of the Caribbean-Andean orogen.

AFTA^TM is a registered trademark of Geotrack International, Pty., Ltd.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France