Controles Precuyanos en la estructura de Cuenca Neuquina

Abstract

An integrated map of the Upper Triassic - Lower Jurassic structures (Precuyano) developed in the eastern region of the Neuquén Basin is presented. The principal grabens, half-grabens, faults and transference zones developed south of Río Colorado are mapped based on 2D and 3D seismic information and previous published works. The general direction of Upper Triassic-Lower Jurassic normal faults is NW. However, two distinct populations can be differentiated. The first one (NW) has directions higher than azimuth 130°, and in general, accommodates the major and deepest grabens and half-grabens (e.g. Entre Lomas and Estancia Vieja). The directions of the second population faults (WNW) are lower than azimuth 110° and in general are related to small and shallower troughs (e.g. Loma la Lata, Agua de Cajón, Lindero Atravesado, Bandurria, etc.). The interaction between both fault populations is not easy to see, tough, in some sectors it can be seen that the second (WNW) cuts the first (NW). Distributed over the whole region there are Upper Jurassic - Cretacic normal faults. These faults are nucleated over the oldest precuyano (Tr-J) faults and over the hinges of the half-grabens. In this work, these normal faults are explained as the result of the tension related to the differential subsidence of the grabens and half-graben infill. These J-K normal faults have general NW directions and are developed parallel to the NW precuyano faults population and en echelon over the WNW population.