Transtensional tectonics induced by oblique reactivation of previous lithospheric anisotropies during the Late Triassic to Early Jurassic rifting in the Neuquen basin: Insights from analog models

The goal of this study was to determine the main factors that controlled the kinematic evolution and the structural architecture developed during the Late Triassic to Early Jurassic rifting that led to the opening of the Neuquen basin in the southwestern sector of Gondwana. We carried out a series of analog models to simulate an extensional system with a bent geometry similar to the northeastern border of the basin. In different experiments, we varied the extension direction between NNE (N10 degrees E) and NE (N45 degrees E) orientations, inducing rift systems with different degrees of obliquity in each sector of the extended area. We compared the kinematic evolution and the final structural architecture observed in the experiments with data from two selected representative areas of the basin: (1) the Atuel depocenter, situated in the northern Andean sector, and (2) the Entre Lomas area, situated in the northeastern Neuquen Embayment. In both cases, the good match between the field and subsurface data and the results of the analog models supports a NNE orientation of the regional extension (N30 degrees E-N20 degrees E) during the synrift stage. Our experimental results suggest that lithospheric weakness zones of NNW to NW trend could have controlled and localized the extension in the Neuquen basin. These previous anisotropies were linked to the sutures and rheological contrasts generated during the collision of terranes against the southwestern margin of Gondwana during the Paleozoic, as well as further modifications of the thermo-mechanical state of the lithosphere during the Late Paleozoic to Early Mesozoic evolution. (C) 2014 Elsevier Ltd. All rights reserved.