Stuart Hardy¹, Rob L. Gawthorpe²
(1) The University of Manchester, Manchester, United Kingdom
(2) University of Manchester, Manchester, United Kingdom

Abstract: Coupling sediment supply and structural controls on sequence architecture in active tectonic settings

The evolution of stream networks has a profound effect upon sediment supply and distribution in active tectonic settings. However, while there has been much numerical modelling of drainage network and fluvial landform evolution, there has been relatively little integration of landform evolution, structural development and the resultant basin stratigraphy.

This paper uses a lattice model of stream network evolution in active tectonic settings to predict sediment supply over geological time-scales. The model is based upon a critical shear stress for fluvial activity, together with a variety of simple displacement fields for faulting and folding. If the shear stress exceeds a threshold value material is removed in order to decrease the local gradient and set the shear stress at the critical value. Eroded material is "routed" along the drainage network and the sediment supply at the drainage outlet(s) computed. The evolution of the stream networks and sediment supply around evolving structures is examined, as are the temporal evolution of sediment supplies from individual catchments.

We develop the model further by coupling the landscape evolution algorithm described above with a three-dimensional model of coarse-grained clastic deposition. The predicted sediment supplies for the multiple drainage basin outlets are used as inputs to the sedimentation model to examine along-strike variability in delta morphology and stacking architectures. In addition to climatic and tectonic controls, the models demonstrate that the inherent spatial and temporal variability of sediment supply can also lead to major along-strike changes in delta morphology and architecture.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana