Abstract A multiproxy approach for evaluating palaeoclimate parameters in deep-time can result in improvements to inter-related factors affecting palaeohydrology. Here we utilize diverse geochemical tools to improve palaeoclimate estimates for the Cedar Mountain Formation (CMF). Prior research utilized stable carbon and oxygen isotopes to develop chemostratigraphic correlations to the late Aptian–early Albian, hypothesized aridity during a positive carbon isotope excursion (CIE) and estimated p CO 2 through this event. This study refines estimates using petrographical analyses, bulk geochemical proxies for mean annual precipitation (MAP) and clumped isotope palaeothermometry. MAP rates range from 736 to 1042 mm a −1 with a slight decrease during the hypothesized aridity event. We interpret warm-biased temperatures (with an average of 32.9°C) that do not vary significantly through the study section. Carbonate nodules are likely to have precipitated in highly evaporative conditions as indicated by the presence of dolomite. Utilizing a simple Rayleigh fractionation model and two estimates of δ 18 O of water, we suggest that evaporation of 2–57% is necessary to result in an enriched end member δ 18 O w . These data suggest that an increase in aridity is a result of lower MAP rates and greater evaporation during seasonal extremes. Lastly, revised p CO 2 calculations suggest overestimates but indicate a shift towards greater concentrations during the positive CIE.

Abstract The oxygen isotopic composition of turtle phosphate from Early (Aptian–Albian) Cretaceous turtles from several North American palaeolatitudes was measured to estimate the isotopic compositions of groundwater δ 18 O w . In Earth's history, under greenhouse conditions, researchers have recorded an intensification of the hydrological cycle as global heat was distributed from the equator to the poles via latent heat transport. Previous studies, using pedogenic carbonate nodules, show an increased rainout effect, causing intense depletion in δ 18 O w at high latitudes due to this phenomenon. This study shows the utility of another palaeo- δ 18 O w proxy, turtle phosphate oxygen from turtle carapace and plastron. Turtle δ 18 O p was sampled from several Early Cretaceous sites. We find that turtle-derived δ 18 O w values range from −3.1 ± 0.9‰ at a palaeolatitude of 29.5° N to −7.2‰ at 40° N. Turtles at the lowest latitude (Arkansas) plot off the carbonate-derived δ 18 O w gradient; however, turtles at 34° N and 40° N plot within the range of carbonate-derived δ 18 O w . Turtles from Arkansas (29.5° N) were likely to have been influenced by marine water and/or enriched Gulf of Mexico water vapour resulting in a deviation from the expected δ 18 O w gradient. These data are encouraging steps towards using turtles to estimate palaeohydrological dynamics; however, additional analysis of lower- and higher-latitude specimens is necessary to confirm this trend.

Multiple cemented channel-fill deposits from the Late Jurassic and Early Cretaceous, once buried beneath 2400 m of sediment, are now exposed at the surface in arid east-central Utah due to erosion of the less resistant surrounding material. This field guide focuses on examples near the town of Green River where there is public access to several different types of exhumed paleochannels within a small geographic region. We describe the geologic setting of these landforms based on previous work, discuss the relevance to analogous sinuous ridges that are interpreted to be inverted paleochannels on Mars, and present a detailed road log with descriptive stops in Emery County, Utah.

Abstract The Kaiparowits Basin, located mostly within Grand Staircase–Escalante National Monument, preserves an outstanding record of Late Cretaceous sedimentation in a foreland basin setting. Hosted in these rocks is one of the most continuous and complete records of this period’s ecosystems known from any one geographic area in the world. Recent work in the basin has emphasized macrovertebrate remains and documented many new sites of high scientific value. Recent stratigraphic studies have further refined our knowledge of the depositional systems and chronostratigraphic relationships. Provided is an overview of some of these recent advances, along with the necessary background to provide context .

Abstract This guide provides background information and an itinerary for a one-day field trip leaving from Price, Utah, and ending near Moab, Utah. The field-trip route identified leads through central and southeastern Utah and provides opportunities to examine features such as the Laramide tectonics manifested in the San Rafael Swell, sedimentary rocks of the Cretaceous Western Interior Seaway and the sandstone arches, extensional faulting, and salt tectonics in and around Arches National Park.