Divergent (extensional) tectonic regimes

Abstract

The main sources of extensional stress in the lithosphere arise from the density imbalances produced by ocean ridges, continental margins and plateau uplifts, and by the forces arising from subduction (see 2.5). Plateau uplifts are relatively common in the continental crust, and even quite small uplifts of the order of 100 km across and 1 km or so high will produce an appreciable extensional stress (see Bott and Kusznir, 1979) . Extensional tectonic regimes are therefore primarily associated with divergent (i.e. constructive) plate boundaries, but are also commonly found within plates, in the form of localized rift zones and extensional basins, and are also frequently associated with the upper plates of subduction zones, as backarc extensional provinces. Strike-slip regimes typically involve local extensional provinces.