Preliminary textural and geochemical data on Cretaceous foreland basin lacustrine limestones from the Wyoming-Idaho overthrust belt indicate post-depositional stabilization of diatomaceous magnesian calcite in closed diagenetic systems. Because resulting mixtures of calcite-dolomite-quartz micrite may preserve nearly pristine isotopic and major element signatures, the project involves an expanded stratigraphic and geochemical study in order to: 1) appraise short-term climate change as recorded in microdolomite content and variation across these areally-extensive lakes, 2) evaluate the role of climate change in predicating clastic-carbonate depositional cyclicity during foreland basin sediment accumulation, and 3) determine naturally occurring stable isotope fractionation factors and trace element distribution coefficients for the system calcite-dolomite-quartz. The scope of this research includes secular variations and carbonate diagenesis within depositional systems leading to greater understanding of paleoclimates. It also ties into other research supported under Geologic Record of Global Change."
