9601975 Ludwig This grant, made through the Academic Research Infrastructure (ARI) Program, provides $200,000 as partial support of the costs of acquiring a state- of-the-art, high abundance sensitivity, thermal ionization mass spectrometer (TIMS) with multiple collectors, to be used for Uranium series and U-Th- Pb geochronology. Specific projects will include the dating of siliceous microfossils, pedogenic silica and carbonate, speleothems, corals and materials from archaeological sites such as tooth enamel using U-series methods for samples in the 20-500 Ka age range and U/Pb techniques for dating of pre-Mesozoic igneous accessory phases. These data should provide new age controls on the late Pleistocene marine stratigraphic record, the timing of pedogenesis and thus climate history of opal-bearing soils, high-resolution records of paleoclimate recorded in spleothem calcites and records of paleosea level based on accurate geochronologies determined from U-series dating of near-surface dwelling corals such as Acropora palmata. The new TIMS will also serve to calibrate Stanford-USGS SHRIMP ion microprobe analyses of individual zircons and will provide independent checks of 40Ar/39Ar dates of volcanic zircons and sanidines obtained using the existing noble gas mass spectrometer at the BGC. Funding of this TIMS will also shared with NSF's Archaeometry Program (SBR-9601068). ***
