--> Abstract: Chronostratigraphic Correlation of the Cody and Mesaverde Formations, Eastern Wind River Basin, Wyoming, by L. D. Little; #91017 (1992).

Datapages, Inc.Print this page

ABSTRACT: Chronostratigraphic Correlation of the Cody and Mesaverde Formations, Eastern Wind River Basin, Wyoming

LITTLE, LAIRD D., Conoco Inc., Ponca City, OK

Correlations of marine shelf, shoreline, and nonmarine clastic strata of the Cody and Mesaverde formations have historically been difficult in the Wind River basin due to rapid lateral facies changes and problems with lithostratigraphic nomenclature. Because of these difficulties, there are numerous examples in the literature of different formation and member names applied to the same stratigraphic units.

This study, based on regional correlations of subsurface well logs and surface exposures, attempts to circumvent previous nomenclature problems by constructing a time-stratigraphic framework for the Cody and Mesaverde intervals in the eastern Wind River basin. This approach correlates time-equivalent packages of strata, and is therefore fundamentally different from previously published lithostratigraphic correlations. The section is subdivided by recognizing stratigraphically significant (regional-scale) bounding surfaces, either unconformities or conformities, that everywhere separate younger rocks from older strata. These surfaces serve to subdivide the stratigraphic section into a series of depositional units ranging in scale from the single progradational event, or parasequence, t the clastic wedge, or sequence. Parasequences and sequences accumulated in the area of the Wind River basin during deposition of the Cody and Mesaverde intervals along the western margin of the Cretaceous Interior Seaway in response to fluctuations of relative sea level.

Most of these chronostratigraphic units can be correlated on well logs throughout the eastern Wind River basin. The correlations provide a means of examining paleogeographic variations along depositional strike through recognition of parasequence sets and parasequence stacking patterns.

Conventional formation and member names are reviewed in the context of a chronostratigraphic framework to illustrate a regional correlation scheme for the following units: Cody Shale, Niobrara, Gammon, Shannon, "Sussex," Mesaverde, Fales, Wallace Creek, Parkman, and Teapot. Specific problem intervals addressed are the Cody "stray sands," including the Shannon zone and the Fales Sandstone and Teapot Sandstone members of the Mesaverde. The correlations demonstrate that high-resolution sequence stratigraphic techniques can be successfully applied to the Cody-Mesaverde interval to gain a more accurate understanding about the distribution of its component strata.

 

AAPG Search and Discovery Article #91017©1992 AAPG Rocky Mountain Section Meeting, Casper, Wyoming, September 13-16, 1992 (2009)