High geothermal gradient metamorphism during thermal subsidence

Abstract

The burial of a basement sequence enriched in heat producing elements during thermal subsidence following rifting produces two concomitant changes in the thermal structure of the crust. Firstly, the burial of the enriched layer produces high geothermal gradients in the overlying sedimentary succession, with the high gradients propagating down into, but not through, the enriched basement sequence. Secondly, the lithospheric thickening that drives thermal subsidence reduces the heat flowing into the deeper crust from the mantle. Because the process of thermal subsidence promotes burial, it naturally increases the depth extent of the high geothermal gradients in the upper crust, potentially ind..