AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Linking Landscape and Stratigraphic Studies in Rift Basins: Implications of Source-to-Sink Studies in Exploration of Syn-rift Plays
(1) Department of Earth Science, University of Bergen, Bergen, Norway.
(2) School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom.
There is still a need to fully couple knowledge and research on rift-related drainage catchment evolution with analysis of depositional systems and stratigraphic evolution in hangingwall depocentres. This integrated approach is needed in order to deconvolve signals of climate, tectonics and sea-level change from the preserved stratigraphic record. Furthermore, attempts at source-to-sink analysis tend to focus on catchment-depositional systems pairs across individual fault zones such that knowledge of the controls and feedbacks at the larger half-graben to rift-scale is more poorly constrained. This coupled understanding of erosional areas and sediment supply, sediment routing and depositional systems is not only of academic interest, it is fundamental to constraining the location, geometry and heterogeneity of syn-rift reservoirs and in developing new plays in syn-rift successions.
At the rift-wide scale, major catchments that supply sediment from the rift shoulders have a dominant effect on gross depositional environments and stratigraphic evolution in both rift margin and rift axis locations. The spacing of the outlet of these rift-shoulder catchments along a rift, like many catchments, is controlled by slope length (in this case the rift shoulder), but are also influenced by the pre-existing drainage network, bedrock lithology and the evolving normal fault array. It is these rift-shoulder catchments that act as major sediment sources to the rift axis. At the scale of individual, border fault zone uplift subsidence variations around growing and linking fault segments impacts on catchment growth and the resulting stratigraphy. Despite a clear tectonic drive forcing catchment evolution, sediment supply and stratigraphic architecture, other factors such as bedrock lithology and fault array geometry have a major impact on the volume and routing of sediment to half graben depocentres.