The role of fluids in the evolution of the South Wales coalfield foreland basin

Abstract

The South Wales coalfield developed as a Silesian flexural basin in response to Variscan tectonic loading in the Bristol Channel and SW England. Subsequent northward propagation of thrust deformation into the coal basin is recorded in the later stages of the foreland basin evolution. The temperatures required for the development of the anthracite field, in the NW of the coalfield, are unlikely to have developed by burial within a normal continental geotherm. It is argued that the style of thrust deformation, in which several thrust detachments parallel to coal seams moved simultaneously, producing a progressive easy-slip thrust (PEST) style, probably required fluid over-pressuring in the coal seams for its development