Description: Robust isotopic reconstructions of climate, elevation, and biology require a reasonable capture of the range of isotopic variability across a paleolandscape. Here, we illustrate how integrating multiple proxies derived from a variety of paleoenvironments aids in this effort. We determined {delta}18O and {delta}13C values from lake and soil carbonates, unionid shells, gar scales, and crocodile teeth from multiple depositional environments (lakes, soils, ponds, streams, and large rivers) spanning a 300 km proximal-to-distal transect within the Late Cretaceous foreland basin of Montana. Two major patterns emerge. First, quiet water environments display higher {delta}18O and lower {delta}13C values than large rivers, which indicates greater input from local precipitation compared to high-altitude runoff, and a relatively larger contribution of degraded vegetative matter to the dissolved inorganic carbon load. Second, proxies with seasonal biases toward late spring and summer growth display lower {delta}18O and {delta}13C values in the basin proximal setting compared to the distal coastal setting, which is linked to the rainout history of vapor masses moving across the foreland basin. Overall these isotopic patterns mirror those in modern catchments, support hypotheses of monsoonal rainfall within the basin, and suggest a hypsometric mean elevation of [~]2.6 km within the Sevier orogenic belt. Furthermore, our results indicate a potential to subdivide freshwater paleoecosystems to refine paleobiologic studies of habitat preference and migration patterns.

Description: Petrographic descriptions and stable oxygen and carbon isotope compositions of microsamples of Campanian-age sediment gravity-flow deposits from Northeast Providence Channel, Bahamas, indicate deep-marine cementation of shallow-marine skeletal grains that were transported to the channel during the Late Cretaceous. Shallow-marine components are represented by mollusks, especially rudists, and shallow-water benthic foraminifers as well as sparse echinoderm and algal grains. The sole evidence of diagenesis in shallow-marine environments consists of micrite envelopes around skeletal grains. Shallow-marine skeletal grains have mean stable isotope values of -3.1 per mil d18O and +2.6 per mil d13C. The d18O values are consistent with precipitation in equilibrium with warm (20°-30°C), shallow-marine water. Deep-marine components are represented by equant calcite spar cements and rip-up clasts of slope sediments. Spar cements, exhibiting hexagonal morphology with scalenohedral terminations, most commonly occur as thin isopachous linings in the abundant porosity. Deep-marine cements have mean stable isotope values of - 1.1 per mil d18O and +2.7 per mil d13C. Deep-marine cements are 18O-enriched relative to shallow-marine skeletal grains, consistent with precipitation in equilibrium with colder (10°-20°C), deep-marine waters. The cement .source during lithification appears to have been dissolution of aragonite and high-magnesium calcite skeletal grains, which made up part of the transported sediment. Interbedded periplatform ooze remains uncemented, or poorly cemented, probably because of lower permeability. Equant spar cements that occur in gravity-flow deposits recovered from Hole 634A have stable isotope compositions similar to spars in Lower and mid-Cretaceous shallow-water limestones exposed on the Bahama Escarpment, to Campanian-Paleocene deep-marine hardgrounds recovered during DSDP Leg 15 in the Caribbean, and to spars in Aptian-Albian talus deposits at the base of the Campeche Escarpment recovered during DSDP Leg 77.