Paleozoic Stratigraphy and Oil Possibilities of Kaiparowits Region, Utah

Abstract

The Kaiparowits region, as defined in this report, covers more than 8,500 square miles in southern Utah. It is essentially a part of a great platform area between the Paradox basin on the east and the Great basin on the west. The Kaibab and Circle Cliffs upwarps, separated by the Kaiparowits basin, are the major structural elements in the region. Cambrian, Devonian, Mississippian, Pennsylvanian, and Permian sedimentary units are present in the subsurface, of which only the Permian is exposed. The lower Paleozoic strata are characteristic products of marine sedimentation on a broad platform bordering the Cordilleran geosyncline. Epeirogenic movements prior to the deposition of the Devonian, and again before Pennsylvanian beds were laid down, were responsible for regional unconformities in pre-Pennsylvanian rocks. Commencing in the early Pennsylvanian, the Kaiparowits region underwent mild orogenic activity related to the ancestral Rockies. The Kaibab and Circle Cliffs uplifts became positive at this time, profoundly affecting sedimentation in the Pennsylvanian strata in a westwardly direction. Continued uplifting caused complet withdrawal of the seas, and in later Wolfcampian time sand dunes swept across most of the region. In Permian Leonardian time the seas again encroached from the west, effecting the deposition of the Toroweap evaporites in a basin in the vicinity of the present Kaiparowits downwarp. The Toroweap passes into a sandstone facies toward the north and east, and is closely related to the Coconino and White Rim sandstones. Equivalents of the Coconino sandstone are found throughout the region, but they occupy only a small interval in the thick sandstone sequences found in the Permian of east-central Utah. The Kaiparowits region has remarkably few major faults except in the western part. A number of anticlinal features exist that have not been drilled for oil or gas, and stratigraphic conditions are favorable for petroleum production at many localities.