HR: 0800h
AN: PP31B-1531    [Abstracts]
TI: Shallow Subsurface Marine Radiocarbon Records from Bahamas Sclerosponge Skeletons
AU: * Rosenheim, B E
EM: brosenheim@whoi.edu
AF: Woods Hole Oceanographic Institution, MS #8, Woods Hole, MA 02543 United States
AU: Swart, P K
EM: pswart@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, MGG University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AB: Initial radiocarbon results from sclerosponges obtained with the intent of understanding their growth rates have been re-interpreted in terms of ²³⁰Th age models constrained with non-radiometric constraints such as the ¹³C Suess effect and increased Pb/Ca during the proliferation of the automobile. The age models are best constrained in from the late 1800's to the late 1900's (time of sampling), however the initial radiocarbon results show interesting structure prior to the 1800's. These results are based on very small carbonate samples, however data from larger samples are currently being analyzed to verify this structure and whether it corresponds with any documented climate phenomena between the 17^th and 19^th centuries. In addition to 18^th century structure in the time series, the Δ¹⁴C values are 25 - 50 permil lighter than previous measurements from corals in the same region. The water mass in which the sclerosponges live (the subtropical underwater) is only 5-10 years removed from surface alteration, thus the difference in Δ¹⁴C is not expected. Therefore, sclerosponges from several different depths are being analyzed to determine if there are depth effects on Δ¹⁴C time series. The results of this study may encourage investigation of Δ¹⁴C time series from potential surface sources of the subtropical underwater, such as the Cape Verde Islands where corals live in the surface ocean along the salinity front marking the boundary of the formation area of Caribbean subtropical underwater. This formation of shallow subsurface water is a significant meridional transport of heat in the N. Atlantic, and while it consists of only a fraction of the heat transported by the Gulf Stream and the thermohaline overturning of the N. Atlantic, connections between the two cells are likely and are being investigated.
DE: 4231 Equatorial oceanography
DE: 4512 Currents
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4918 Cosmogenic isotopes (1150)
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005