CONICET | Buscador de Institutos y Recursos Humanos

The analysis of volcano-sedimentary infill in sedimentary basins constitutes a challenge for basin analysis and hydrocarbon exploration worldwide. In order to understand the contribution of volcanism to sedimentary record in such basis we study the Jurassic effusive-explosive volcanic infill of an inverted extensional depocentre at the Neuquén Basin, Argentina. A cause and effect model that evaluates the relationship between volcanism and sedimentation was devised to develop conceptual models for the tectono-stratigraphic evolution of that volcanic rift basin. We show how the variations in the volcanism, coupled with the activity of extensional faults, determined the types of volcanic edifices (i.e., composite volcanoes, graben-calderas, and lava fields). Volcanic edificescontrolled the stacking patterns of the volcanic units as well as of the sedimentary systems. The landform of the volcanic edifices, as well as the styles and scales of the eruptions governed the volcaniclastic input to the basin, setting the main variables of the sedimentary systems, such as provenance, grain size, transport and deposition and geometry. As a result, the contrasting volcaniclastic input, from higher volcaniclastic input to lower volcaniclastic input, associated with different subsidence patterns, determined the high-resolution syn-rift infill patterns of the extensional depocentre. The cause and effect model presented in this study cleared the variables of the volcanic environments which set those that control the sedimentary scenarios. We suggest that adjusting the first order input parameters of the model this could be adapted to other similar rift basin, in order to establish predictive facies models with their stratigraphic controls, and the impact of the volcanism on their stratigraphic records.