The role of climate in stratigraphic patterns exhibited by late Palaeozoic rocks exposed in Kansas

Late Palaeozoic “cyclothems” of the midcontinental U.S. cannot be represented by a single ideal facies sequence. Rather, they encompass a wide range of cycle types depending on their stratigraphic position. The exposed Late Palaeozoic (Pennsylvanian and Permian) rocks of Kansas, as compiled by Zeller (1968), can be divided into nine major lithofacies. These lithofacies were ordered based on their times of greatest abundance through the section. From oldest to youngest, they attain their peak abundance in the following order: (1) coal; (2) gray mudrocks and sandstones; (3) black mudrocks; (4) limestones; (5) cherty limestones; (6) fossiliferous mudrocks; (7) variegated mudrocks; (8) evaporites; and (9) variegated dolomitic siliciclastics. Climatically, these nine lithofacies suggest a change from generally wetter, at the base, to generally drier, at the top of the section. This climatic trend was probably generated by a complex interaction of factors primarily driven by global tectonics. Climatic changes can be used to explain the five generally recognized types of lithofacies “cyclothems” in Kansas, and thus are a potential explanation for the changing stratigraphic patterns of the entire Late Palaeozoic time interval of Kansas, and perhaps elsewhere.