Abstract The purpose of this field trip is to examine the sedimentology, sedimentary architecture, stacking patterns, and correlation of fluvial, coastal plain, deltaic, and shoreface to shelf deposits in the low accommodation Desert Member to Castlegate Sandstone stratigraphic interval (Campanian), Book Cliffs, eastern Utah. Traditional sequence stratigraphic models of falling stage deposits will be tested against an alternative sequence stratigraphic model that links the nonmarine to shallow-marine facies belts in both time and space. The trip will focus on the exceptional three-dimensional outcrop exposures in the Thompson Pass to Sagers Canyon region. At least eight sequence stratigraphic rock packages are identified and correlated, and these combine to form two progradational parasequence sets. The lower set comprises Desert Member rock packages 1-7, while the upper set comprises the SM/CC-2 rock package and overlying nonmarine strata of the Castlegate Sandstone. Rock package 7 is bounded above and below by coal-bearing, carbonaceous-rich zones. Correlation of the Upper and Lower Coal zones across the Crescent Canyon to Blaze Canyon region establishes a clear chronostratigraphic link between the nonmarine and shallow-marine strata of the Desert-Castlegate interval. The “fusing/welding” of rock packages 7 and SM/CC-2 with underlying cliff-forming sandstones in the South Face-Central to South Face-East region of Horse Heaven further demonstrates the chronostratigraphic link between the nonmarine and shallow marine. The alternative sequence stratigraphic interpretation of the Desert-Castlegate interval connects the nonmarine and shallow-marine facies belts in time and space, through correlation of coals, marine flooding surfaces, multi-storey channel complexes, and falling stage shallow-marine successions. “High-frequency” fluvial incision surfaces (sequence boundaries) merge to form a diachronous, lithostratigraphic contact between the nonmarine and shallow-marine facies belts. These contacts were previously defined as the “Desert SB” and “Castlegate SB” by J.C. Van Wagoner and were linked to longer term sea-level falls. Subsequent analysis of the “Desert SB” has revealed an amalgamation of “high-frequency” sequence boundaries that merge and split in a complex manner. Each “high-frequency” surface represents a shorter term portion of the longer term falling sea-level curve, which is equivalent to a parasequence-scale relative fall in sea level. “High-frequency” sequence boundary development, forced regression, and minor coastal plain aggradation occurs during the falling limb of the shorter term sea-level curve, followed by shallow-marine flooding, valley in-fill, coastal plain aggradation, and regional coal deposition during the rising limb of the shorter term sea-level curve. Individual nonmarine to shallow-marine chrono-slabs stack together. Inter-slab incision is rare in shallow-marine sections and where noted is relatively gentle (<3 m incision). In contrast, inter-slab incision is more significant in coastal plain settings due to reduced accommodation under falling stage conditions. The chrono-slab, parasequence-scale model for falling stage deposits in the Desert-Castlegate interval has four facies belts or zones. These record the transition from (i) nonmarine settings with single storey channels and scattered multistorey channel-fill complexes, to (ii) large-scale, multi-storey channel-fill successions (IVFs), to (iii) interbedded large-scale, multi-storey channel-fill successions (IVFs) and sandstone-rich proximal shallow-marine deposits, to (iv) proximal to distal, shoreface to shelf parasequences. This alternative chrono-slab model is likely applicable to falling stage deposits worldwide, especially those within a foreland basin setting. Ongoing research will extend the chrono-slab correlations outside of the study area and examine the relationship between relative sea-level history and chrono-slab thickness, facies belt length, and number of facies belts per chrono-slab.

Abstract Shelf turbidite bodies have long been recognized in ancient rock successions, but most examples are poorly constrained both by the limited outcrop exposures and by the lack of modern analogues or data. Uncertainties include the mechanism or mechanisms responsible for generating the turbidites, the mode of transport onto and across shelf, the relationship to time-equivalent shoreface deposits, and the resulting three-dimensional sand-body geometry or sedimentary architecture. This study takes advantage of the exceptional outcrop exposures in the Book Cliffs of eastern Utah to answer some fundamental questions regarding the origin and distribution of shelf turbidite bodies. The lower Kenilworth Member (Campanian, Blackhawk Formation) is an extremely well constrained stratigraphic interval and is characterized by turbidite-rich shelf deposits at a number of localities. The outcrop exposure is excellent, with some areas offering unparalleled three-dimensional transects across the shelf, along both depositional dip and depositional strike. A sedimentological analysis of the lower Kenilworth Member shelf deposits in the Price River Canyon to Hatch Mesa area has revealed a mixture of high-energy event beds, including wave-modified turbidites, hummocky cross-stratified sandstones, hyperpycnites, and classical turbidites, that are interbedded with quiet-water mudstones and siltstones. The paucity of wave-generated fair-weather deposits, combined with an abundance of wave-modified event beds, suggests deposition between fair-weather and storm wave base. Fresh-water input is indicated by the presence of carbonaceous matter, and the low-diversity and low-abundance trace-fossil suite in all facies. These shelf turbidite bodies are detached from their time-equivalent Kenilworth parasequence 2 (KPS2) shoreface deposits. The Middle Mountain to Gunnison Butte lenticular body was deposited at least 10 km basinward of the KPS2 shoreline in approximately 25-30 m water depth, and the Hatch Mesa succession was deposited 16 km basinward of the KPS2 shoreface in approximately 35-45 m water depth. Sediments bypassed the shoreface through a network of subaqueous channels which were cut by the turbid underflow of sediment and water generated by storm and/or river flood events. The results of this study indicate that shallow marine facies models should be revised to include isolated or shoreface-detached turbidite complexes in some shelf settings. Preliminary work suggests that the generation and preservation of these isolated sandstone bodies is linked to a short-term period of tectonic uplift and subsidence in the Sevier thrust front, northwest of the Book Cliffs. Further work is required to test the validity of this tectonic hypothesis.

Abstract The 300-km-long Books Cliffs are a world-class field laboratory for studying clastic sedimentology, sedimentary architecture, and sequence stratigraphy, and serve as an outcrop analog for fluvio-deltaic and shoreface-to-shelf hydrocarbon reservoirs worldwide. These famous rocks have been used to develop, test and refine sedimentological and stratigraphic ideas and models over the years, including the principles and concepts of sequence stratigraphy. This field guide focuses on the following themes: (a) sedimentology, sedimentary architecture, and sequence stratigraphy of fluvial, coastal plain, river- and wave-dominated deltas, and shoreface-to-shelf deposits, (b) stacking patterns in high versus low accommodation settings, (c) distribution of reservoir and non-reservoir facies in a predictive sequence stratigraphic framework, (d) relationship between relative sea level, shoreline position, and stratigraphic architecture, and (e) alternative sequence stratigraphic models for the interpretation of channel-shoreface packages. Keywords: accommodation space, Book Cliffs, Cretaceous, deltaic, fluvial, sedimentaryarchitecture, sedimentology, sequence stratigraphy, shelf, shoreface, Western InteriorSeaway

Abstract Marine mudstone-encased, inner shelf sandstone bodies are concentrated in a 70–90-m-thick interval that spans the upper Aberdeen and lower Kenilworth members (Blackhawk Formation, Campanian), Book Cliffs, eastern Utah. These sandstone bodies contain a complex mixture of event beds including wave or storm-modi-fied turbidites, hummocky cross stratified sandstones, hyperpycnites, and/or classical turbidites. The turbiditic channel-fills and lobes were deposited below fair weather wave base and are detached from their time equivalent shoreface deposits. Shallow marine facies models should be revised to include turbiditic-rich channels and lobes in some inner shelf settings. A three-component shoreface-to-shelf model, consisting of delta front deposits, subaqueous channels, and prodelta turbidites, is proposed to explain the depositional setting and environment of the Mancos Shale–encased sandstone bodies. Oceanic- or river-flood induced hyperpycnal flows were responsible for cutting a network of subaqueous channels on the inner shelf and for transporting fine-grained sediments from the shoreface to the inner shelf. Other Mancos Shale–encased isolated sandstone bodies in eastern Utah and western Colorado should be reexamined in the light of the new data and models presented herein.

Abstract Estuarine mudstones occur in the central basin of many wave-dominated valley-fill systems. These mudstones are flanked on the landward side by the sandstones of the bay head delta and on the seaward side by the sandstones of the barrier island, tidal inlet and/or flood-tidal delta (marine sandstones). The longitudinal transition from bay head delta sandstones to central basin mudstones to marine sandstones defines the tripartite facies zonation. Central basin mudstones are observed in the Crystal and Sundance/Edson valley-fill deposits of the Viking Formation in central Alberta. These deposits are underlain by the bioturbated mudstones and siltstones of the regional parasequences (highstand systems tract). The central basin mudstones are distinguished from the regional mudstones by their sedimentology, ichnology and vertical facies succession.