Petrographic Analysis of Campanian Sandstones, Kaiparowits Formation, South-central Utah

Perkes, Tyson L. and William W. Little
Brigham Young University-Idaho, Rexburg, ID

     A Petrographic analysis of fluvially-deposited sandstones from the Kaiparowits Formation of south-central Utah shows an abrupt increase in the relative abundance of feldspar and lithic fragments at approximately 70 meters from its base. This compositional change is likely due to the introduction of new sediment source areas as the Sevier Thrust Belt advanced from the west. The compositional transition appears to also coincide with a change in alluvial architecture associated with rapid basin subsidence in front of the advancing Sevier Thrust Belt. Petrographic data suggest that these sandstones are genetically related to fluvially deposited Upper Cretaceous sandstones of the Mesaverde Group exposed in the Book Cliffs and Price Canyon of eastern Utah, where Lawton (1983, 1986) observed a similar vertical petrofacies change from quartz-rich sandstones in the Bluecastle Tongue of the Castlegate Sandstone to orthoclase- and lithic-rich sandstones in the Farrer Formation. Petrographic data obtained in this study, along with paleodrainage data and the correlation of changes in alluvial architecture within the Kaiparowits Formation and the Mesaverde Group, indicate that the Mesaverde Group is the downstream equivalent of the Kaiparowits Formation.

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah