PETROLOGY OF SANDSTONES FROM THE DRIP TANK MEMBER OF THE STRAIGHT CLIFFS FORMATION AND THE LOWER WAHWEAP FORMATION, CRETACEOUS, SOUTHERN UTAH

Two measured sections were taken and petrographic samples collected through the Drip Tank Member of the Straight Cliffs Formation into the lower part of the Wahweap Formation near the area of the type section of the Drip Tank Member on the Kaiparowits Plateau. Another measured section and additional petrographic samples were taken across potentially the same stratigraphic horizons on the eastern margin of the Paunsaugunt Plateau within Bryce Canyon National Park to assess lithologic correlations between the type section and the Paunsaugunt Plateau. The coarse sandstones of the locally conglomeratic Drip Tank Member contain distinctive metamorphic quartzites, abundant microcline, and large chert clasts. The sandstones in the overlying Wahweap Formation are rich in carbonate clasts and lack the metamorphic quartzite lithics and microcline of the Drip Tank Member. This suggests a shift in source area from the south (metamorphics of the Mongollon Highlands of Arizona?) during deposition of the Drip Tank Member to the west during deposition of the Wahweap Formation which incorporates abundant lithic fragments from the carbonate units exposed in the Sevier orogenic belt.