HR: 09:15h
AN: PP41E-06 INVITED    [Abstracts]
TI: Ostracode Mg/Ca Paleothermometry: Applications and Complications
AU: * Cronin, T M
EM: tcronin@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive, Reston, Va 20192, United States
AU: Dwyer, G S
EM: gsd3@duke.edu
AF: Duke University, Division of Earth and Ocean Sciences Nicholas School of the Environment and Earth Sciences, Durham, NC 27708, United States
AB: Ostracode (bivalved Crustacea) shell Mg/Ca paleothermometry has wide applicability in Cenozoic paleoclimatology over 10¹ to 10⁷ year timescales because they are commonly fossilized, live in freshwater, shallow- and deep-marine habitats, and grow by molting, which minimizes Mg/Ca variability due to ontogenetic variability. Two empirically derived Mg/Ca-temperature calibrations based on core top and culturing include one for the shallow marine, estuarine genus Loxoconcha (5 to 30°C) and another for deep-sea genus Krithe (<1 to 14°C). The former produced a temperature history for Chesapeake Bay for the last millennium, which has been intensively analyzed in the context of the hockey stick temperature curve. The latter produced evidence for decreased deep-sea temperature during glacial intervals and the first Atlantic-wide reconstruction of deep-sea temperature during the warm mid-Pliocene. In addition to temperature, however, factors such as host-water magnesium concentrations, salinity, intra-shell, intra-population, and interspecific variabilility, seasonality, biological factors (shell secretion rate), and post-mortem dissolution can contribute to scatter in calibration datasets and uncertainty in paleotemperature estimates. We will review these processes, present a new 2000 year Chesapeake temperature record, and discuss its relation to twentieth century climate change.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4924 Geochemical tracers
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting