Melt generation at volcanic continental margins: No need for a mantle plume?

Melt generation in a rifting environment is studied using a dynamic 2-D finite element model. The lithosphere is extended to large, realistic thinning factors assuming a mantle temperature of 1333°C. The focussing of deformation results in a distribution of thinning factors along the margin at breakup time consistent with observations. The timing of melt production (late synrift) and the amounts of melt are consistent with observations at volcanic margins. The dynamical processes related to lithospheric rifting enhance the produced melt volumes sufficiently to explain the sometimes enigmatic melt volumes found at volcanic margins.