Foreland basins: lithospheric flexure, plate strength and regional stratigraphy

Abstract

Foreland basin subsidence through time is reproduced in this study, as the flexure of an elastic beam in an inviscid fluid under the vertical stress, caused by discrete-distributed loads. Thus, seismostratigraphic data from the Timor Sea peripheral foreland basin, in northwestern Australia, and the Putumayo retroarc foreland basin in the Colombian Andes, are forward modeled, at chronostratigraphic intervals, to assess the evolving geodynamic conditions of the basins. Results show that the accommodation in foreland basins varies as the depositional basement is vertically adjusted according to the regionally isostatic compensation of the lithosphere. Distributed tectonic (thrust belts) and sedimentary loads that act independently but consecutively during tectono-stratigraphic events, throughout the evolution of foreland basins, control the deflection of the plate that forms the foredeep of these depocenters. Accordingly, the loads limit the amount and distribution of available space for sedimentation. Results also reduce the role of eustasy to only 2 to 6% of the total accommodation, even in marine foreland depocenters. The strength of the plate remains invariable during the evolution of the basin at time scales of 106 to 107 m.y. Asymmetrical flexure, produced by oblique plate convergence, induces diachronuous and local marine cycles at basin scale (100’s of km). Stratigraphic development of non-marine foreland basins is more likely to respond to the evolution of the equilibrium-profile during basin history.