Subsidence in intracontinental basins due to dynamic topography

The origin of anomalous tectonic subsidence (ATS) of large intracontinental basins long after their most recent phase of extension and last thermal perturbation is the subject of a long standing debate. We show that deep-Earth processes may contribute to the subsidence of these tectonically stable basins by analysing the Tertiary mantle convection-cl riven topography history of a global set of more than 220 intracontinental basins, integrated into a plate kinematic framework. Most basins are affected by increasing negative dynamic topography over the last 70 Myr. due to the motion of many continents away from large mantle upwellings and towards downwellings previously located along the perimeter of the supercontinent Pangaea. During continental dispersal, increasing negative dynamic topography causes dynamic subsidence of the basins, creating additional accommodation space. We utilise a parameter from a global crustal analysis of intraplate basins, termed anomalous tectonic subsidence, to quantify sediment accumulation not related to crustal stretching. We propose that dynamic subsidence due to plate motions relative to the underlying mantle, as well as variations in the large-scale convection patterns can significantly contribute to the creation (and destruction) of accommodation space in intraplate basins. (C) 2008 Elsevier B.V. All rights reserved.