HR: 0800h
AN: PP31B-0422    [Abstracts]
TI: Culture-based Calibration of the Benthic Foraminiferal Mg/Ca Paleothermometer: Initial Results
AU: * Lincoln, S A
EM: slincoln@mit.edu
AF: Dept. of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, United States
AU: Filipsson, H L
EM: Helena_L.Filipsson@geol.lu.se
AF: GeoBiosphere Science Centre, Dept. of Geology, Lund University, Solveg. 12, Lund, RI SE- 223 62, Sweden
AU: Bernhard, J M
EM: jbernhard@whoi.edu
AF: Dept. of Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Mailstop 52, Woods Hole, MA 02543, United States
AU: McCorkle, D C
EM: dmccorkle@whoi.edu
AF: Dept. of Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Mailstop 52, Woods Hole, MA 02543, United States
AU: Shimizu, N
EM: nshimizu@whoi.edu
AF: Dept. of Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Mailstop 52, Woods Hole, MA 02543, United States
AU: Birdwhistell, S P
EM: sbirdwhistell@whoi.edu
AF: Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Mailstop 23, Woods Hole, MA 02543, United States
AB: The magnesium calcium (Mg/Ca) paleothermometer has become a widely used tool for estimating deep water temperatures. To date, calibrations of the proxy have relied on core-top samples; in such studies, water chemistry and biological factors including food supply often co-vary with temperature, making it difficult to isolate the true Mg/Ca / temperature relationship. A multi-temperature culture experiment was conducted at the Woods Hole Oceanographic Institution from December 2006 through May 2007 in order to study the relationship between Mg/Ca and temperature under controlled conditions. Several species of benthic foraminifera were collected from four locations (the Skagerrak and Gullmar Fjord, Sweden; the Bahamas; and the Charleston Bump, United States; 70 to 800 m water depth), and were grown in microcosms under known, constant physical and chemical conditions at 3.5, 7.0, 14.0, and 21 C. Bulimina species ( B. aculeata and B. marginata) were the most successful, reproducing at 7.0 and 14.0 C and adding chambers at all temperatures. These newly added chambers are the focus of our first Mg/Ca analyses. Because cultured benthic foraminifera are typically lightly calcified, sensitive microanalytical techniques with high spatial resolution are required to measure trace element concentrations in single chambers of cultured specimens. We have explored the use of both secondary ion mass spectrometry and laser ablation inductively coupled mass spectrometry for this application, and present preliminary Mg/Ca data from Bulimina species across the experimental temperature range.
DE: 0419 Biomineralization
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3030 Micropaleontology (0459, 4944)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting