From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, November 5, 2010
Source-To-Sink Sediment Volumes Within A Tectono-Stratigraphic Model For A Laramide Shelf-To-Deep-Water Basin
Link to streaming video TBA: available 11.05.2010 at 8:55am
Dr. Cristian Carvajal and Ron Steel
Jackson School of Geosciences, University of Texas at Austin
In the Laramide-type Washakie-Great Divide Basin, we illustrate how sediment volume partitioning integrated into basin analysis contributes to understanding the history of uplift, interpreting the stratigraphic drivers, and to producing a source-to-sink characterization. The studied Lewis-Fox Hills (Maastrichtian) source-to-sink system that filled the Laramide basin shows a two-stage evolution. In Stage 1, increasing thrust-driven uplift and crustal loading led to increased subsidence resulting in a shelf-margin that was aggradational with increasing clinothem volumes and widening marine topsets, as the shelf-margin prism prograded into deepening basinal waters. In Stage 2, the shelf-edge trajectory became more progradational with decreasing clinothem volumes, wide coastal-plain topsets and stable to decreasing clinoform heights. This is inferred to have resulted from lower accommodation and increased rates of sediment supply, as well as progradation into low-subsidence distal basin areas; thrust-driven uplift is inferred to have decreased or ceased. Through stages 1 and 2, average sediment supply increased from around 4 to 16 x 106 ton/y (or slightly more) and yield was within 200-2000 ton/ km2/y with the higher end of this range likely achieved during Stage 1. Hinterland maximum relief evolved from lowland (100-500 m), to upland (500-1000 m), and at some point in Stage 1, to mountainous (1000-3000 m) remaining in this category through Stage 2. The studied Laramide source-to-sink system was similar to some modern East Asian river systems, which at present provide some of the largest volumes of sediment to the oceans. The study case illustrates that integration of sediment volume partitioning with dynamic stratigraphic analysis is useful to build improved tectono-stratigraphic models and characterize ancient source-to-sink systems.