Monagas Foreland Thrust Belt, EasternVenezuela
The Monagas Foreland Thrust Belt, located in the Eastern Venezuelan Basin (EVB), isthe result of a Neogene compression related to the oblique collision between Caribbeanand South-American plates.
Structural Interpretation
Three main tectonic provinces define the Monagas foreland thrust belt: The Interior Ranges -“Serrania del Interior,” the Pirital block, and the Monagas foothills. The integration of subsurface, seismic-structural interpretation, and surface structural profiles enabled the description and characterization of the structural styles for each of these three main tectonic provinces. Three main thrust systems were interpreted to have been emplaced at different periods. The youngest thrusts (highlighted in red color) generated smaller short-wavelength anticlines. The oldest thrust systems (assigned in blue and green colors) generated wider structures reactivating and deforming previous thrusts.
Geodynamic setting of Eastern Venezuela Basin (EVB).
Present day plate structure of the Caribbean region. Subduction type B to the east between Atlantic and Caribbean-South American plates. At the north, subduction type B of the Caribbean Plate. In the south, Subduction type A of the South American plate. (Modified from Jacome 2001, after DeMets et al. 1994, Kellogg, et al. 1995, Mascle and Letouze, 1990, and Audemard and Lugo, 1996.) Topographic and bathymetric map are from The National Geophysical Data Base, 1988.
Three-dimensional correlation of regional seismic profiles tied to surface features shows that not only three different thrust systems can be identified in cross sections, but also two different families of thrusts can be correlated in a map view. These two different sets of thrusts are bounded by their respective lateral ramps. The systems are named here as the First Pirital thrust system to the west, and the Second Pirital thrust system to the east. The southeastern end of the very well known “Urica fault zone” has been interpreted as the western lateral ramps of the First Pirital system. The subsurface interpretation of a new system of lateral ramps (Fig. 16) to the east of Urica and to the south of the also known “San Francisco fault” was the principal criteria to divide the Pirital system into two separate families of thrusts. As a result, it is proposed here that the Pirital block should be divided into two different blocks: the Manresa block and the Pirital-Cerro Corazon block.