EVAPORITE KARST IN THE GREATER PERMIAN BASIN OF TEXAS, NEW MEXICO, OKLAHOMA, KANSAS, AND COLORADO: AN OVERVIEW AND AN UPDATE ON USGS NATIONAL KARST MAPPING

The Greater Permian evaporite basin, a composite of the Anadarko, Dalhart, Delaware, Denver, Midland, Palo Duro, and Salina Basins; underlies an area of about 176,000 mi² (454,000 km²) in Texas, New Mexico, Oklahoma, Kansas, and Colorado. Evaporite rich formations within the basin typically occur at depths of 30-1300 ft (10-400 m). This area is an important domain for exploration and development of energy and other natural resources. Knowledge of the extent of both surface and subsurface evaporite rocks is critical to mitigating collapse hazards for a myriad of human activities including siting of hydrocarbon exploration and distribution equipment, the location of wind turbine tower sites, pipelines, and transportation corridors. Evaporite mineral-bearing rocks with potential for karst development in the Permian basin include, in Texas: the Blaine, Briggs, Castile, Gatuna, Malone, Quartermaster, Rustler, and Salado Formations; the Dewey Lake Redbeds; and the Clear Fork and Whitehorse Groups. In New Mexico: the Castile, Grayburg, Queen, Salado, Seven Rivers, Yates, Tansill, and Yesa Formations, and the Artesia, Chinle, and San Raphael Groups. In Oklahoma: the Blaine, Cloud Chief, Marlow, and Rush Springs Formations; Dog Creek and Flowerpot Shales; and, El Reno and Whitehorse Groups. In Colorado: the Lykins, Morrison, and Ralston Creek Formations. In Kansas: the Big Basin Formation, and Nippewalla and Sumner Groups.

The USGS produced a report and digital database on the nationwide extent of rocks at the earth’s surface with potential for development of karst features (USGS Open-File Report 2014-1156). This report is based on analysis and compilation of state geologic map data at various resolutions. The database contains information on lithostratigraphic unit names, gross lithology, age, wet vs dry climate setting, ecoregion, and links to online source data. The report also includes a rough delineation of areas potentially underlain by evaporite rocks and the principal evaporite basins. Since publication, the data behind the 2014 report has been modified, largely in response to suggestions by state geological survey experts, and it has also been supplemented with information on the occurrence of caves by lithostratigraphic unit.