A PRELIMINARY PALEOENVIRONMENTAL ANALYSIS OF A PLANT QUARRY IN THE KAIPAROWITS FORMATION OF THE GRAND STAIRCASE ESCALANTE NATIONAL MONUMENT, UTAH

The Kaiparowits Formation, located in south central Utah, is a record of a Late Cretaceous floodplain that drained the highlands of Laramidia into the Western Interior Seaway. The formation is highly fossiliferous and contains fossil plants, invertebrates, fish, amphibians, reptiles, and mammals, many of them new to science. The large-scale interpretation of this formation has been previously described as fluvial and floodplain deposits with various swamp and pond deposits within. This study provides a detailed sedimentological description of a small fossil plant quarry and interprets the depositional environment.

The quarry is located above a conglomeratic sandstone unit that fines upward into a series of alternating fine-grained sandstones and green mudstone layers. The quarry itself is composed mostly of friable green to grey mudstone that is located between two sandstone units. After measuring the stratigraphic section, samples were collected every 10 centimeters and analyzed for mineralogical content and grain size. From this data, we interpret the depositional environment as a crevasse splay.