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Joint Meeting Pacific Section, AAPG & Cordilleran Section GSA April 29–May 1, 2005, San José, California

Balance and Restoration of Regional Section: Thrust Belts Systems, Eastern Inner Ranges in the Eastern Venezuelan Basin

Pablo E. Ghinaglia
Geophysics, Universidad Central de Venezuela, Edificio de Geolgía, Ciudad Universitaria, Los Chaguaramos, Caracas 1041A Venezuela, [email protected]

The aim of this study is to describe the tectonic evolution in an area located in Eastern Venezuela. The following structures were present: triangular zones in thrust systems faults, systems of inverse faults and reactivation of pre-cretaceous systems faults. Among the most important results is that the produced deformation occurs under a transtensive tectonic regime that responds to simple shear deformation. Using three algorithms according to the mechanisms of restoration of the blocks (datum restoration, flexural slip and trishear zone) there are two values of shortening, one at the beginning of late Miocene, with a value of 3.1 km, affecting sequences between horizons SM2 and SBMI2; the second with a value of 11.5 km for sequences between horizons SK2 and SE4, occuring from the Pliocene to the Recent. Also, the recovered profile can give a value of eroded section of around 5 km. The take-offs are associated at the following stratigraphy levels, one within the Pre-Cetacean sequence, a second during Middle to late Miocene at and the third during late Miocene to recent. The structures are the result of a combination of those involved in deformation and deformation of the sedimentary cover. Finally, it is understood that the present architecture of the Eastern basin of Venezuela is the result of a superposition of events, where the oldest exert their influence on the sequences which overlay them. Pre-foreland sequences have controlled the development of the active margin, thus causing effects of tectonic inversion and inheritance on the most recent sequences.

Posted with permission of The Geological Society of America; abstract also online ( © Copyright 2005 The Geological Society of America (GSA).