Accurate Calibration of Multiple Paleoceanographic Proxies in Benthic Foraminifera

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Under this award the PIs will calibrate multiple paleoceanographic geochemical proxies in several species of benthic foraminifera. This work should contribute significantly to the understanding and application of benthic foraminiferal geochemical proxies. Since such measurements form the foundation of many paleoclimatic studies, improved calibrations are essential and will be widely employed. Proxies include estimators for temperature and salinity (Mg/Ca, d18O), nutrient content (Cd/Ca, Zn/Ca, d13C), pH (d11B), and possibly carbonate ion concentration (U/Ca, Li/Ca). A series of multicore tops and seawater samples were collected from 38 locations between Florida and Cuba in 2002, expressly for this purpose. This collection represents a unique calibration opportunity for several reasons: (1) abundant benthic foraminifera, high sedimentation rates, and large volumes of collected sediment allow for multiple measurements of near-modern specimens; (2) the sites span large ranges of the targeted parameters (e.g., 15 C, 1.9 psu, 0.24 pH); and (3) seawater collected from a Niskin bottle mounted on the multicorer provides accurate determinations of in-situ water conditions, namely salinity, d18O, elemental concentrations, and carbonate system parameters (accurate temperatures are available from accompanying CTD casts).