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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 45 (1995), Pages 267-274

Shelf-Slope Break Sedimentation and Erosion during Deposition of the Claiborne Group in Colorado and Wharton Counties, Texas

Robert A. Hull

ABSTRACT

Geological and geophysical data over a 6,500 square kilometer area across Wharton and Colorado Counties, Texas, are utilized to understand sedimentary processes that occurred along the shelf-slope break of the Eocene Claiborne Group. Sedimentation models based on seismic profile data and well log data are critical to the oil and gas industry.

It can be demonstrated that Claiborne deposition generally took place in middle neritic water depths on the shelf, however, some sediment did bypass the shelf and was deposited in deeper waters downdip. Sands of the Yegua Fm. were transported basinward from the deltaic and fluvial depositional environments in the updip area of Colorado County, bypassing shelf deposition. In general, there was little sedimentation taking place along the shelf except during short periods of transgression. Downdip at the shelf-edge, subsidence rates were higher and sedimentation became more aggradational. Possible drops in sea-level and/or changes in depocenter locations brought about downdip deposition of sediment beyond the shelf edge during most periods of Yegua-age deposition. It appears that even during low accumulation times on the shelf, sediment was being deposited downdip beyond the shelf-edge.

Slumping along the over-steepened shelf margin was common during Claiborne deposition. The style of Claiborne age slumping was controlled by many factors including the placement of the Wilcox shelf. During high sedimentation times, erosion of the shelf margin from slump related carving appears to have taken place.


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