Recent advances in non-marine facies analysis of siliciclastic systems have recognized the deposits of large fluvial systems that exit upland catchment regions into fan-shaped accumulations. Here, Trendellet al. integrate sedimentologic, stratigraphic, paleopedologic, geochronological and petrographic observations to assess the depositional processes and forcing mechanisms of the Chinle Formation at Petrified Forest National Park, USA. Upsection changes in grain size, channel width and depth, mineralogical maturity, and character of paleosols are interpreted to represent deposition in a progradational, large fan. Changing paleosol character is interpreted to reflect progressively more upland deposits resulting from progradation, rather than climate shifts. These results illustrate another large fan system, and show how apparent shifts in climate can result from autogenic processes of fan progradation.
Facies analysis of aprobable large-fluvial-fan depositional system:the Upper Triassic Chinle Formation at Petrified Forest National Park, Arizona,U.S.A. by Aislyn M. Trendell, Stacy C. Atchley, and Lee C. Nordt