Estimation of Sediment Yield from Ancient River Catchments
The sediment yield of ancient river systems are estimated using multiple regression of topographic and climatic variables derived from paleo-earth system models. Previous workers (ie Hovius, 1999 and Syvitski and Milliman, 2007) have shown that the observed sediment yield in modern rivers can be explained by a combination of topographic, geological, climatic and anthropogenic factors. A similar relationship has been determined for ancient river systems using topography derived from paleogeographic reconstructions and climatic data from paleoclimate simulations.
Regression analysis shows the paleo-sediment yield can be explained by 3 groups of parameters a) topography, b) metrics of drainage basin morphology and c) temperature. The regression relationship was tested against the sediment yield of modern river systems and found to account for 71% of the variation in observed values. Data on lithology and vegetation in the geologic past was not available for entire paleo-drainage basins but may explain some of the remaining uncertainty. The method also predicts the locations river mouths for paleo-earth systems based on hydrological analysis of a paleo-DEM. These estimates are within 75km of time-equivalent deltaic deposits. The resulting sediment yields are also compared with published data on sediment volumes stored in selected basins to better understand where this approach is most appropriate. The method is most suitable for passive margin systems with large drainage basins.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009