Connections Across the Shelf-Slope Transition, Late Quaternary Rio Grande Deltaic System
Julia S. Wellner, John B. Anderson, Laura A. Banfield, 2013. "Connections Across the Shelf-Slope Transition, Late Quaternary Rio Grande Deltaic System", Shelf Margin Deltas and Linked Down Slope Petroleum Systems–Global Significance and Future Exploration Potential, Harry H. Roberts, Norman C. Rosen, Richard H. Fillon, John B. Anderson
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The Rio Grande Delta, offshore south Texas, has been a prominent feature on the continental shelf throughout the last glacial-eustatic cycle. Eight hundred km of high-resolution seismic data (20 in3 airgun, single-channel) has been collected on the upper slope in order to extend previous interpretations of the shelf deltaic system. In addition, a series of cores collected in the 1960s on the Rio Grande slope have been incorporated into the project. During the last lowstand (~20,000 Ka), a large shelf-margin delta and related slope fan have developed. These lowstand deposits represent a large volume of sediment that formed partially by cannibalizing the highstand shelf deposits. Preliminary interpretation of the data indicates that the shelf-margin delta is a fluvial-dominated system and the slope fan is composed of a number of turbidites, characterized on seismic data by chaotic clinoforms interbedded with pelagic sediments. We believe the turbidites have originated directly at the shelf-margin delta front, and thus the development of the delta and fan are intricately linked. We will use this newly integrated data set to study the connection between the shelf and slope systems and to construct a chronology of the timing of slope fan development.