Pre-Des Moines (pre- "Thirteen-Finger" limestone), Des Moines, Missouri, and Douglas sediments were deposited by a transgressive Pennsylvanian sea which originated in the Ouachita geosyncline and invaded the western Mid-Continent through the Ardmore and Anadarko basins. Successively younger Pennsylvanian beds overlapped older from the Anadarko basin onto the Central Kansas uplift, and unconformably onlapped pre-Pennsylvanian Paleozoic rocks. During this transgressive phase the Anadarko basin expanded areally as shown by the shelfward migration of (1) the hinge lines and (2) the shelf-carbonate to basin-shale facies changes. When the Anadarko basin expanded to merge with the McAlester basin on the east, blanket sandstones in the latter moved progressively westward into the Anadarko basin.

During Shawnee, Wabaunsee, Council Grove-Admire, and Chase deposition the sea began to withdraw from the western Mid-Continent and move toward the West Texas region through the Dalhart and Palo Duro basins. The Anadarko basin diminished in areal extent as hinge lines moved basinward, and became an embayment off the thicker deposits on the southwest. Shelf-carbonate to basin-shale facies changes moved progressively basinward, and blanket sandstones became successively smaller in areal extent. Permian red shales and sandstones shed by the Apishapa and Front Range uplifts were deposited in the western Mid-Continent in the wake of the retreating sea.

End_of_Article - Last_Page 130------------