Dissolution-collapse breccias and paleokarst resulting from dissolution of evaporite rocks, especially sulfates

The lithological trinity of dolostone, limestone, and sulfates (anhydrite and/or gypsum) is subject to rapid dissolution of the sulfates and leads to the development of dissolution-collapse breccias resulting from the withdrawal of the sulfates. The resultant features commonly include spectacular dissolution-collapse breccias. Owing to their mobility and chemical instability evaporite rocks, such as gypsum and anhydrite, are highly soluble and can be dissolved rapidly to form karstic features.When anhydrite and/or gypsum are dissolved the overlying continuous strata of carbonate rocks collapse, generating dissolution-collapse breccia composed of carbonate clasts. Such dissolution-collapse breccias as a result of dissolution of gypsum and/or anhydrite are more common worldwide than the literature suggests.Evaporite karst interferes with human activity, including highways, buildings, canals, and agriculture.A Cretaceous deposit composed of dolostone, limestone, and anhydrite breccia set in a carbonate matrix has been interpreted as the result of asteroid- or comet collision. An origin as evaporite paleokarst could explain the formation of this same breccia.In the Williston Basin of Montana anhydrites form the caps of basin-wide peritidal cycles in successions which brine upward. The supratidal cycle caps are zones of anhydrite leaching and creation of dissolution-collapse breccia.Cambro-Lower Ordovician (Sauk) platform cycles in the Appalachian Basin are composed of peritidal upward-shallowing carbonate facies which show evidence of ultimate emergence. The sulfates in the cycle caps have entirely dissolved out and the paleokarst serves as testament to their former presence.