Seismic evidence for ductile necking of the mid-lower crust beneath the Columbrets Basin (Western Mediterranean)

Abstract

The Columbrets Basin is the largest Mesozoic rift basin of the Valencia Trough in the Western Mediterranean. The analysis of a seismic- reflection survey makes it possi-ble to reconstruct the tectonic fabric underlying the sedimentary basin, including the structure of the top of the lower crust and the Moho. It is proposed that the ductile deformation of the mid- lower crust was the main mechanism controlling the basin geometry, with the radial flow of mid- lower crust coeval with the reactivation of two large- offset SW-dipping normal faults, inherited from the precursor Permian–Triassic rifting. Mid- lower crustal necking occurred below the major depocenters, immedi-ately before hyperextension. Our results provide new insight into the formation of circular-shaped basins and the evolution of depth-dependent extensional processes during rifting.