Tectonic control of the sedimentary record and stress-induced fluid flow: constraints from basin modelling

Abstract

Abstract Many basins show deviations from the simple subsidence pattern predicted by the stretching model for basin evolution. Incorporating finite strength of the lithosphere during rifting and stresses acting on the lithosphere during the post-rift phase of basin evolution can successfully explain these deviations. Finite strength of the lithosphere during rifting causes flexurally supported rift-shoulders. The erosion of these rift-shoulders induces both additional uplift at the basin margin and sediment loading-induced subsidence in the basin centre, causing tilting of syn-rift sediments. A ‘break-up’ unconformity results from the progressive diminishing of this tilting towards the end of the rifting period, separating the syn- and post-rift sediments. As the amount of erosion is primarily controlled by climatic conditions, basins having the same tectonic history but, for example, located at different lattitudes will not have developed the same pattern of stratigraphic fill. The same effect is expected if another mechanism causes the uplift of the basin margin, as, for example, a change in the level of intraplate stress. Plate reorganizations are the main cause for changes in the level of intraplate stress. We demonstrate that the in-plane stress variations affect the fluid flow regime in rifted basins, with possible implications for the diagenesis of sediments, primary migration of hydrocarbons, faulting and localization of economic resources. Examples include the North Sea and Pannonian Basin. An increase in the level of compressive stress causes flank uplift and basin centre subsidence, inducing a contemporaneous increase of meteroic water influx and compaction-driven fluid overpressures. An increase in the level of tensile inplane stress induces the opposite effects.