Abstract
This paper briefly summarizes two of the important by-products of lithospheric extension during rifting. These are partial melting and the segregation and migration of basaltic melt to crustal levels, and the dynamical consequences of viscous flow in the lower lithosphere and asthenosphere. In both cases, the rift-stage subsidence may be significantly different from that predicted by a simple stretching model and may allow relative uplift of the rift zone, as well as subsidence. The dynamical model also predicts significant uplift of the rift shoulders, doming over the entire rift zone, and asymmetrical continental breakup at rifted continental margins. The relative importance of these predictions depends on the thermal and mechanical properties of the lithosphere. The model predictions help explain some of the discrepancies between the observed behaviour of rifts and results obtained from the simple stretching models.