Animated models of extensional basins and passive margins

Abstract

We present animated models of the development of the San Jorge, North Falkland, and North Sea extensional sedimentary basins and the Orange, Pearl River Mouth, and Vøring passive continental margins. These animations show the link between strain rate and subsidence and track both compaction and thermal development of the sediment pile. Calculations are based on a two-dimensional inverse model for extracting the spatial and temporal variation of strain rate from stratigraphic profiles across extensional terrains. This general algorithm requires no a priori assumptions about the number, duration, and intensity of the rifting episodes. Instead, strain rate is allowed to vary smoothly through space and time until misfit between observed and predicted stratigraphy is minimized. Calculated 2-D and 1-D strain rate histories are corroborated by the number and duration of rifting episodes determined from independent stratigraphical and structural evidence. The evolving temperature structure of the sediment pile is a function both of porosity, which varies through time as compaction occurs, and of heat flow into the base of the basin, which is determined from the strain rate history. We discuss the implications of the calculated strain rate histories for understanding the regional tectonic development of each basin and margin. Copyright 2004 by the American Geophysical Union.