Type section of the Kiowa formation age and environment(s) of deposition, Southern Kansas

Abstract

The Type Section of the Kiowa crops out in southern Kansas (Kiowa County). Sedimentary, petrographic and paleontological analyses were conducted on outcrops in Kiowa County to determine environment of deposition and age of the formation. There are three main facies in the type Kiowa: a dark shale derived from current transported muds, sandstone from currents, and shell conglomerates that represent disturbed neighborhood assemblages or storm transported assemblages. XRD results show that the dark shale facies is dominated by illite, smectite and kaolinite clays. The sandstone is dominated by quartz, and the shell conglomerates by calcite with a matrix dominated by quartz. Paleontological analyses uncovered 11 different species of mollusks, 3 species of foraminifera and trace fossils of Fodinichina or Domichnia. The environment was determined to be a shallow marine setting near an opening to an estuarial bay or barrier bar in a shallow marine setting based on the presence of certain sedimentary structures, facies and differences of illite concentrations. The age of deposition is Late Albian ~102.5 Ma to ~101Ma based on correlation of similar units in North America and timing of transgressive events via sequence stratigraphy.