Some consequences of compressional tectonics for extensional models of basin subsidence

Abstract

Changes in intraplate stress levels have important consequences for the stratigraphy of rifted basins and provide a tectonic explanation for the generation of sequence boundaries. Late-stage compressional phases during the post-rift evolution of basins produce unconformities, with offlap phases that increase in magnitude with the age of the rifted basin. Late-stage compression has not only a strong bearing on the generation of unconformities, but also induces significant downbending of the centre of a basin. Ignorance of the vertical motions of the lithosphere induced by late-stage compression during post-rift evolution can, therefore, give rise to substantial errors in the estimates of crustal extension derived from analysis of basement subsidence using stretching models. Consequently, late-stage compression can be of great significance in estimates of depth and timing of the hydrocarbon-window inferred from extensional models of basin subsidence. Quantification of the subsidence induced by post-rift compression has important implications for integrated models of basin subsidence and hydrocarbon generation.