9418087 Allmendinger Two fundamentally different tectonic styles are exhibited by fold/thrust belts- those involving basement (thick-skinned) and those involving only cover (thin skinned). Previous work has shown that thick and thin-skinned deformation are both active simultaneously in the Andes at 30oS, and the boundary occurs across a geometric triangle zone between the central precordillera and the eastern precordillera, Sierra Pampeanas. This project will use a unique industry seismic reflection data set and fieldwork to investigate the hypothesis that the dramatic change of structural geometry is controlled by preexisting anisotropies in the crust of western Argentina. Results should help explain the controls on thick or thin deformation styles in fold-thrust belts.
