--> Abstract: High-Resolution Sequence Stratigraphic and Chronostratigraphic Investigations of the Lower Shelf and Basinal Lithofacies of the Mississippian Subsystem in the Southern Midcontinent U.S.A, by Willard L. Watney, Evan K. Franseen, John H. Doveton, Thomas L. Thompson, Darwin R. Boardman, Troy Rasbury, David K. Newell, John Victorine, Neil Suneson, and Edith Starbuck; #90078 (2008)

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High-Resolution Sequence Stratigraphic and Chronostratigraphic Investigations of the Lower Shelf and Basinal Lithofacies of the Mississippian Subsystem in the Southern Midcontinent U.S.A

Willard L. Watney1, Evan K. Franseen2, John H. Doveton1, Thomas L. Thompson3, Darwin R. Boardman4, Troy Rasbury5, David K. Newell1, John Victorine1, Neil Suneson6, and Edith Starbuck3
1Kansas Geological Survey, University of Kansas, Lawrence, KS
2KU Department of Geology, Kansas Geological Survey, Lawrence, KS
3Geological Survey Program, Missouri Department of Natural Resources, Rolla, MO
4T. Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK
5Department of Geosciences, SUNY Stony Brook, Stony Brook, NY
6Oklahoma Geological Survey, University of Oklahoma, Norman, OK

Chert-rich Osagean carbonate strata form important reservoirs, especially in shelf/ramp margin locations of the Anadarko and Arkoma Basins. Long standing issues remain regarding the temporal and spatial distribution of lithofacies along the shelf-to-basin transition that could be important to delineating additional gas resources.

Quantifying lithofacies distribution within depositional sequences using wireline logs, core, and surface exposures coupled with chronostratgraphy and organic geochemistry are improving the understanding of controls on deposition along the complex, structurally defined shelf/ramp-to-basin transition. Meter- to decimeter scaled, unconformity bounded, high-frequency depositional sequences form accretionary packages along the shelf margin consisting of thin beds of transgressive encrinitic grainstone/packstone, thin condensed sections consisting of black claystone, nodular chert, or dark micritic limestone, succeeded by sparsely fossiliferous dolosiltstone and argillaceous crinoidal wackestones with isolated chert nodules. Sequences are capped by thick, oil- and gas-bearing biostromal beds of chert with secondary micropores and are commonly brecciated. Initial results indicate distinct chert-dominated sequences can be correlated to carbonate-dominated sequences shelfward and basinward to sequences dominated by dark chert, limestone, and dark, organic-rich shales.

High-frequency, high-magnitude sea-level fluctuations, and syndepositional tectonism were major controls on sequence development and facies distribution. The predominance of sequences composed of siliceous sponge-dominated and heterozoan carbonate facies extending across the entire ramp/shelf suggest paleoceanographic conditions that provided excess nutrients and dissolved silica, likely coming from basinal areas, in this subtropical/tropical setting.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas