Controls on Deposition of the Tordillo Formation in Southern Mendoza (34 degrees-36 degrees S): Implications for the Kimmeridgian Tectonic Setting of the Neuquen Basin

The Tordillo Formation is a continental succession of redbeds deposited in the Neuquen Basin during the Kimmeridgian. Based on sedimentological and structural evidence we document an extensional setting between 34 degrees and 36 degrees S, in the northern part of the basin, which contrasts with a transpressional environment in the Huincul arch region (39 degrees S). The tectonic setting of the Neuquen Basin, during the deposition of the Tordillo Formation, was controlled by the combined stresses generated by the subduction system to the west and the break-up of Pangea to the east. We propose that trench roll-back in the Late Jurassic caused regional extension in the back-arc zone. This stress field was locally modified by the clockwise rotation of South America due to the initial break-up of Pangea that ended with the opening of the South Atlantic Ocean. This rotation produced a transpressive stress field in the southern Neuquen Basin in which the structures generated during the Permian collision of the Patagonia terrane were reactivated as strike-slip and reverse faults leading to variable basin geometries and subsidence patterns recorded by the Tordillo Formation in the north and south.