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Sediment Budget Distribution in a Source-to-Sink Transect (Late Campanian Western Interior Basin, SW Wyoming and N Colorado)

Carolina Gomez

University of Texas at Austin, Jackson School of Geosciences, Department of Geological Sciences

Austin, Texas

[email protected]

The problem of how the total sediment budget is differentially stored and by-passed along source-to-sink time slices is currently a research topic of significant interest in the Sedimentary Geology community.

In order to quantify the amounts of sediment differentially sequestered during one complete cycle of relative sea level fall & rise, at both 4th and 3rd order time scales, a working hypothesis will be used. This hypothesis predicts that during early and main stages of relative sea level fall, erosion and sediment bypass occur throughout the upstream part of the system, whereas widespread progradation and deposition occurs from the shoreline out into the basin. During sea level rise, however, almost the opposite happens, i.e., there is transgressive erosion and minimal deposition across the new marine shelf but significant sediment sequestering in the most proximal parts of the system.

Outcrop and subsurface data will be integrated to create a regional 400 km transect running from southwest Wyoming to north-central Colorado. This transect will be used to assess the 2-D sediment partitioning along the regressive and transgressive segments of the system.

In the proximal parts of the system this project will analyze the Campanian Trail and Rusty members of the Ericson Sandstone, in southwest Wyoming. Moving to the southeast, the intermediate (shoreline) reaches will be studied using the coeval Iles Wedge in the Sand Wash Basin. Finally, the distal zone will be monitored in the Muddy Buttes-Hygiene-Carter and Hygiene-Terry Sandstones in the Middle Park and Denver Basins.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid