An Exceptional Tectonic Setting along the Andean Continental Margin

Abstract

The Late Jurassic?Early Cretaceous Vaca Muerta Formation deposited in the Neuquén Basinhas an exceptional development, in the thickness of its sequences and in the volume ofits sedimentaryrecord. These marine deposits, which constituted the source rock of conventionaloil and gas for more than a century, continue to be an important source of unconventionalhydrocarbons 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 otherbasins of Late Jurassic to Early Cretaceous age along the same continental margin, they standout even more. The basin development and preservation parallel to the continental marginare discontinued by important processes of subduction erosion. The analysis of the thickestand widest part of the basin (the Neuquén Embayment) shows that its large development isrelated to the combination of two rift systems, a north?northwest system truncated by an almosteast?west system. These two extensional systems were developed in the hanging-wallsof sutures between different crustal terranes that formed the basement of the Neuquén Basin.The paleogeographic development and the structure of these basement terranes are the controlthat conferred to the Neuquén Basin and its Embayment their unique characteristics.