HR: 1340h
AN: PP33B-1573    [Abstracts]
TI: Sub-Millennial Scale Climatic and Hydrologic Variability in the Gulf of Mexico during the Early Holocene
AU: * LoDico, J M
EM: jlodico@marine.usf.edu
AF: University of South Florida, 140 7th Avenue South, St. Petersburg, FL 33701 United States
AU: Flower, B P
EM: bflower@marine.usf.edu
AF: University of South Florida, 140 7th Avenue South, St. Petersburg, FL 33701 United States
AU: Quinn, T M
EM: quinn@utig.ig.utexas.edu
AF: University of South Florida, 140 7th Avenue South, St. Petersburg, FL 33701 United States
AB: Sediment core MD02-2550 from Orca Basin located in the northern Gulf of Mexico (GOM) provides a high-resolution early Holocene record of climatic and hydrologic changes from ~10.5 to 7 thousand calendar years before present (ka). Paired analyses of Mg/Ca and δ¹⁸O on the planktonic foraminifer Globigerinoides ruber (white variety, 250-355 μm) sampled at ~ 20 year resolution were used to generate proxy records of sea surface temperature (SST) and the δ¹⁸O of seawater in the GOM (δ¹⁸O_GOM). The Mg/Ca-SST record contains an overall ~(~1.5 °C warming trend from 10.5 to 7 ka that appears to track the intensity of the annual insolation cycle and six temperature oscillations (~0.5-2 °C), the frequency of which are consistent with those found in records of solar variability. The δ¹⁸O_GOM record contains five ~0.5 ‰ oscillations from 10.5 to 7 ka that bear some resemblance to regional hydrologic records from Haiti and the Cariaco Basin, plus a ~ -0.8 ‰ excursion that may be associated with the "8.2 ka event" recorded in Greenland air temperatures. The δ¹⁸O_GOM record, if interpreted as a salinity proxy, suggest large salinity fluctuations (> 2 ‰) reflecting changes in evaporation-precipitation (E-P) and Mississippi River input to the GOM. Percent Globigerinoides sacculifer records from three cores in the GOM exhibit remarkably coherent changes, suggesting episodic centennial-scale incursions of Caribbean waters. Spectral analysis of the Mg/Ca-SST and the δ¹⁸O_GOM time series indicate that surface water conditions may be influenced by solar variations because they share significant periods of variability with atmospheric Δ¹⁴C near 700, 200, and 80-70 years. Our results add to the growing body of evidence that the sub-tropics were characterized by significant decadal to centennial-scale climatic and hydrologic variability during the early Holocene.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 4934 Insolation forcing
DE: 4954 Sea surface temperature
DE: 4999 General or miscellaneous
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005