Quantitative subsidence analysis and thermal-mechanical modelling: examples from southern Spain and Libya

The stratigraphic record of sedimentary basins provides key information on vertical motions of the lithosphere and consequently on the tectonic subsidence underlying the formation and evolution of these basins. A procedure commonly called "backstripping' is used to extract the tectonic subsidence information from well data. This technique uses microstratigraphic data on depositional environments expressed in terms of water depth and geologic ages (in million years) to produce burial plots from the stratigraphic record, incorporating porosity changes. Thermomechanical models predict the behaviour of the lithosphere under stress and sediment loading, given a characteristic strength expressed in terms of the flexural rigidity. The model results can be compared with observed tectonic subsidence from backstripping analysis to yield information concerning paleostress patterns shaping the basin. -Author