--> ABSTRACT: Stratigraphic Sequence of a Transgressive Barrier-Bar System, Red Fork Sandstone, Wakita Trend, Grant County, Oklahoma, by Kathleen L. O'Reilly; #91039 (2010)

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Stratigraphic Sequence of a Transgressive Barrier-Bar System, Red Fork Sandstone, Wakita Trend, Grant County, Oklahoma

Kathleen L. O'Reilly

The stratigraphic sequence of the Red Fork sandstone (Boggy Formation, Krebs Group) along the Wakita trend, north-central Oklahoma, is interpreted as a transgressive barrier-bar system. The Red Fork sands were deposited along the northern shelf of the Anadarko basin in an elongate belt about 1-7 km wide. Within the belt, the sandstone forms podlike bodies ranging from 1 to 16 km long.

The Red Fork is positioned in a generally onlapping sequence of strata, from the Inola Limestone Member at the base to the Tiawah ("Pink") Limestone Member at the top. Shales that are interpreted as lagoonal deposits underlie and have a sharp contact with the Red Fork. To the north, the underlying shale is variegated green and red, and contains abundant rootlets and woody detritus; shale to the south is dark-gray and contains abundant brachiopod fragments. Glauconitic siltstone and shale overlie and have a gradational contact with the Red Fork sandstone.

Sedimentation of the Red Fork sand was apparently localized on an east-west-striking hinge formed by increasing dip on the surface of the Inola. Shale overlying the Inola thickens to the south, forming a relatively flat surface upon which Red Fork deposition occurred. No evidence exists of valleys or channels cutting into shale underlying the Red Fork sandstone.

Sedimentary structures in the Red Fork sandstone support interpretation of the stratigraphic sequence as a barrier-bar complex. Sandstone geometry and the nature of the encasing rocks are distinctly characteristic of transgressive barrier-bar systems.

AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.