ABSTRACT: Sequence Stratigraphy of the Lower Cretaceous Dakota Aquifer Framework, Kansas

COLEMAN, JANET, Amoco Production Co., Tulsa, OK, and SUSAN TURBEK, Kansas Geological Survey, Lawrence, KS

The Lower Cretaceous Dakota aquifer framework of Kansas consists of deposits belonging to three stratigraphic depositional sequences. The Lower Cretaceous section is bounded at its base by a major erosional surface, a Type 1 unconformity or sequence boundary. The Cheyenne Sandstone overlying the unconformity is an incised valley fill deposit. The Kiowa Formation is separated from the underlying Cheyenne by a transgressive surface and is comprised of marine and shoreline sediments of transgressive and highstand systems tracts. Another Type 1 sequence bounding unconformity separates the Kiowa from the overlying Dakota Formation. The basal J sandstone of the Dakota Formation was deposited in an incised valley-fill fluvial complex. In extreme northwestern Kansas, a remnant of the marine d posits of the transgressive systems tract is preserved as the Huntsman Shale. A minor base-level fluctuation followed the incursion of the Huntsman Sea and developed a Type 2 erosional unconformity. The lowermost D sandstone is the coarse basal fluvial deposit of the updip portion of a shelf margin wedge. The deltaic and paralic sections of the D sandstone and the marine Graneros Shale in the transgressive systems tract were deposited along and in a sea that flooded over the coastal plain clay of the upper Dakota that, in turn, overlaid the alluvial plain deposits of the lower Dakota Formation.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)