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Changes in Trace-Fossil Assemblages and Paleosols in the Upper Triassic Chinle Formation, Stevens Canyon Area, Southeastern Utah: Implications for Interpreting Paleohydrology and Paleoclimate

Sean Fischer
Geology, University of Kansas, Lawrence, KS, USA
[email protected]


Regional models have interpreted increasingly arid conditions during deposition of the Upper Triassic Chinle Formation in the southwest United States. This study will determine whether local changes in the distribution of sedimentary facies, ichnofossils and paleosols of the Chinle Formation with respect to stratigraphic successions in the Stevens Canyon area, southeastern Utah follow this trend. Ichnofossils and paleosols provide detailed information on local hydrology, climate, and depositional setting; however, there are few detailed descriptions of ichnofossils and paleosols in the Chinle Formation. Characterizing the lithostratigraphic associations of ichnofossils and paleosols to establish ichnopedologic facies will aid in interpreting local paleohydrologic and paleoclimatic changes. These changes affected sediment body geometries and local to regional climatic patterns for western Pangea during the Late Triassic. Ichnofossils, paleosols, and sedimentary facies will be described from a measured master stratigraphic section in the Stevens Canyon area and from multiple sections laterally. Field samples and thin-sections will be utilized for fine-scale description of ichnofossils and paleosols. X-ray diffraction will measure bulk chemistry and clay content of rock samples. Ichnopedologic facies will be constructed using associations of sedimentary facies, ichnofossils and paleosols in outcrop. Increased knowledge of ichnofossil and paleosol distribution in the Chinle Formation will help interpret climate variability during time of deposition. Better characterization of sandstone, carbonate, and mudstone bodies and depositional environments will, in turn, facilitate evaluating potential hydrocarbon reservoirs in continental settings.

AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects