Stresses Associated with Continental Break-Up

Abstract

The structural setting of passive margins indicates major extensional stress during the rifting stage. Local gravitational loading stresses which develop as the lithosphere thins are not large enough to have much influence on the tectonic development. A source of sufficiently large renewable extensional stress to cause lithospheric failure is the hot, low-density upper mantle of the type associated with a plume. Widespread extensional stress may also result from subduction on opposite sides of a large continental plate. These two sources of extensional stress may combine to initiate and cause break-up. The abrupt change to a more subdued stress regime at the onset of seafloor spreading can be explained by abrupt weakening of the lithosphere at the newly forming plate boundary.