ABSTRACT

The Upper Ferron Sandstone in southern Castle Valley, Utah, is a river-dominated deltaic complex made up of seaward-stepping, vertically stacked, and landward-stepping cycles. These cycles, which consist of delta plain, delta front, and prodelta/offshore facies associations, are partitioned by flooding surfaces that detailed biostratigraphic analysis indicates lack an open marine signature. They are thought to be abandonment flooding surfaces associated with delta lobe switching. The abundance of distributary channel belts associated with all cycles suggests that riverine processes controlled the evolution of their associated delta fronts and that the entire Upper Ferron is a river-dominated system in which marine processes (predominantly waves and storms) played a subordinate role. Autocyclic processes, channel avulsion and lobe switching, controlled the internal architecture and partitioning of the cycles. The stacking pattern was controlled by allocyclic processes, primarily decreasing sediment supply combined with increasing accommodation. No compelling evidence was found to confirm the presence of incised valleys in the Upper Ferron.