Facies of the Ferron Sandstone, East-Central Utah

Abstract The Upper Cretaceous Ferron Sandstone represents a spectrum of depositional environments and facies spanning offshore marine to alluvial plain. Because they are very well exposed, are readily accessible, and have been extensively studied, these deposits serve as excellent analogs for many oil and gas reservoirs. Sediment was delivered to the Ferron depositional system by eastward- to northward-flowing rivers represented by sandy channelbelts. The rivers were generally meandering, although some were lower-sinuosity streams. Flood basins adjacent to the channelbelts accumulated predominantly muddy sediment, sandy crevasse-splay deposits, and, locally, peat. Peat accumulated in belts that roughly correspond to the lower part of the coastal plain and generally paralleled the shoreline. The geometries of individual, thick bodies of coal vary greatly. The dynamics of peat accumulation was controlled primarily by the rate of relative sea level rise. The balance between sediment supply and wave energy was such that most Ferron shorelines were characterized by wave-dominated, cuspate deltas that graded laterally into strandplains. During the early part of Ferron deposition, however, the supply of sediment was great enough that fluvial processes predominated locally. Lobate deltas with numerous distributaries and interdistributary bays were well represented. Shoreface and delta-front deposits graded seaward into offshore marine mud. Sandy Ferron shoreline strata interfinger extensively with marine shale. Elongated sand bodies or sand plumes accumulated on a shallow-shelf area that lay east and northeast of the Ferron shoreline during early Ferron deposition. Barrier islands developed during transgressions and are preserved, along with the lagoons that lay landward of them, at the “turnaround” points where episodes of transgression ended and shoreface progradation began. Landward pinchouts of the shoreface sandstone bodies are a key element for deciphering the transgressive-regressive history of the Ferron Sandstone. Tidal inlets and associated flood-tidal deltas are present locally in the vicinities of the landward pinchouts.