Role of pore pressure generation in sediment transport within half-grabens
Y. You and M. Person
Journal name: Basin Research
Issue: Vol 20, No 3, September 2008 pp. 419 - 429
Info: Article, PDF ( 531.29Kb )
Sediment transport and overpressure generation are coupled primary through the impact of effective stress on subsidence and compaction. Here, we use mathematical modeling to explore the interactions between groundwater flow and diffusion-controlled sediment transport within alluvial basins. Because of lateral variation in permeability, proximal basin facieswill have pore pressure close to hydrostatic levels while distal fine-grained facies can reach near lithostatic levels. Lateral variation in pore pressure leads to differential compaction, which deforms basins in several ways. Differential compaction reduces basin size, bends isochron surfaces across the sand-clay interface, restricts basinward progradation of sand facies, and reduces the amplitude of oscillation in the lateral position of the sand-clay interface especially in the deepest part of the section even when temporal sediment supply are held constant. Overpressure generation was found to be sensitive to change in sediment supply in permeable basins (at least 10-17m2 in our model). We found that during basin evolution, temporal variations in overpressure and sediment supply £uctuations are not necessarily in phase with each other, especially in tight (low permeability) basins (<10-17m2 in our model).