Boron Isotope Paleoceanography

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9501530 Spivack It has been argued that the boron isotopic composition of foraminifera test are a function of both the isotopic composition of seawater and pH. Initial data indicates that the B isotopic composition of seawater has been nearly constant over the past 20 Myr while fossil foraminifera tests exhibit a decreasing trend between 7.5 and 20 Ma. This data has been used to infer changes in surface ocean pH, approximately constant between 7.5 Ma and the present and with an increasing trend form 20 Ma (pH 7.4 4 + 0.2) to 7.5 Ma. Investigators on this project will: 1. Conduct a systematic intercomparison of the &11B of common planktonic species isolated form recent sediments, 2. systematically examine the foraminifera 11B.