Brenner 9628128 We propose to collect and interpret the stable isotopic paleoclimatic record of meteoric carbonates from Albian through Turonian strata along the eastern margin of the Western Interior Basin along a paleolatitudinal transect between Kansas and Manitoba (Fig.6). Our research has shown that meteoric phreatic cements along the cratonic margin of the basin yield 18O values that are characteristic of coastal lowland environments, and are therefore more directly applicable to paleoclimatic reconstructions for North America than freshwater carbonates in the western margin facies where they are affected by orographic complications. The results of this work will be used to construct sets of paleogeographic map consisting of 1-2 m.y. time slices that portray paleolatitudinal gradients of meteoric phreatic carbonate 18O values. These values and maps could be used by other researchers to constrain experimental simulations of mid-Cretaceous climate systems using an emerging generation of global generation circulation models (GCMs) that include hydrological tracers. Ongoing biostratigraphic studies are providing a more refined chronostratigraphic framework necessary for the time-slice analysis in the eastern margin area. The most challenging part of the chronostratigraphic correlations occurs within the dominantly nonmarine Albian to mid-Cenomanian portion of the section. Work is underway on this portion of the section using a combination of palynostratigraphy and aspects of sequence stratigraphy modified for use in this setting. Preliminary results are encouraging, with a workable palynostratigraphic framework established for western Iowa and eastern Nebraska. This work is currently being extended into southeast Nebraska. Additional core and outcrop samples from Kansas, Nebraska, and the Manitoba Escarpment will provide biostratigraphic data needed to relate nonmarine sequences to previously delineated marine sequences (e.g., Kauffman et al., 1993). Project objectives are t o investigate mid-Cretaceous paleoclimate and paleogeography during a significant greenhouse period along a north-south paleolatitudinal transect of the eastern margin region of the Western Interior Basin. The project will use an integrated approach combining biostratigraphy, sedimentology, sequence stratigraphy, and stable isotope geochemistry. Stratigraphic analyses and samples will span the outcrop belt that extends from central Kansas to Manitoba and Saskatchewan, Canada (Fig. 6).
