An Exceptional Tectonic Setting along the Andean Continental Margin

Abstract

Abstract The Late Jurassic–Early Cretaceous Vaca Muerta Formation deposited in the Neuquen Basin has an exceptional development, in the thickness of its sequences and in the volume of its sedimentary record. These marine deposits, which constituted the source rock of conventional oil and gas for more than a century, continue to be an important source of unconventional hydrocarbons as a producer of oil- and gas-shale and have a large potential future. When the exceptional characteristics of the Vaca Muerta Formation are compared to other basins of Late Jurassic to Early Cretaceous age along the same continental margin, they stand out even more. The basin development and preservation parallel to the continental margin are discontinued by important processes of subduction erosion. The analysis of the thickest and widest part of the basin (the Neuquen Embayment) shows that its large development is related to the combination of two rift systems, a north–northwest system truncated by an almost east–west system. These two extensional systems were developed in the hanging-walls of sutures between different crustal terranes that formed the basement of the Neuquen Basin. The paleogeographic development and the structure of these basement terranes are the control that conferred to the Neuquen Basin and its Embayment their unique characteristics.