HR: 08:45h
AN: PP41E-04    [Abstracts]
TI: Controls on the uptake of magnesium, other trace metals and stable isotopes in foraminiferal calcite from a seasonal sea-ice environment
AU: * Hendry, K
EM: kathh@earth.ox.ac.uk
AF: Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AU: Rickaby, R
EM: rosr@earth.ox.ac.uk
AF: Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AU: Meredith, M
EM: mmm@bas.ac.uk
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: Elderfield, H
EM: he101@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom
AB: The stable isotope and trace metal chemistry of planktonic foraminiferal calcite has become a key geochemical tool for the understanding of past sea surface temperature, salinity and nutrient conditions. However, the use of proxies such as Mg/Ca at high latitudes, in particular the Southern Ocean, is hampered by the lack of preservation, poor sensitivity at low temperatures and other complicating factors such as seasonality in sea-ice cover, salinity, temperature and carbon fluxes. Here, we present a year long monthly time-series study of the foraminifera, Neogloboquadrina pachyderma (sinistral), from sediment traps deployed off the West Antarctic Peninsula in a seasonal sea-ice environment. This species is found in sediment cores from polar regions and is consequently a promising means for understanding past high latitude environmental change. Our data show a clear seasonal signal in the uptake of metals heavier than calcite (e.g. Cd, Ba, Sr). However, the uptake of stable isotopes and lighter metals, including Mg, is more complex and is evidently sensitive to environmental parameters, most likely a combination of ambient temperature, salinity and carbonate ion concentration. We discuss the implications of seasonality, low temperature and sea-ice for the use of pachyderma Mg/Ca, other trace metals and stable isotopes as palaeoproxies.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1065 Major and trace element geochemistry
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 4924 Geochemical tracers
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting