Stretching in continental back-arc basins: Insights from subsidence analysis of the Neuquén Basin, Argentina

Abstract

In the present contribution, we apply forward modelling and subsidence analysis to determine the initial lithospheric structure and the Neuquén Basin central area's stretching factor. The forward models determined that the initial thickness of the crust and the lithosphere would have been around 30 km and 100 km, respectively. Airy and regional isostasy models were considered for the calculation of the tectonic subsidence in outcrops and the subsurface. In both cases, results are very similar due to an elastic thickness of ~3 km for the beginning of the basin, which allows considering the Airy isostasy model as the representative for the analyzed period in the study area. Regarding the stretching factor, the results suggest that the extension varies between 1 and 1.32 for the analyzed area. Although these values seem to be higher than the previous estimations for the Neuquén Basin, they are consistent with those mentioned in the literature for the back-arc basins around the world with similar lithosphere structure and tectonic subsidence values. Furthermore, it should be mentioned that similar tectonic subsidence values could be obtained for the same area considering a lower stretching factor and a westward lithospheric thickening associated with the Neopaleozoic orogeny.