Calibration of Holocene Paleoenvironmental Proxy Records from the Northern Gulf of Mexico

A quantitative understanding of natural and anthropogenic influences on the Earth's climate system is necessary to better anticipate future changes in climate. While paleoclimate reconstructions provide information regarding the timing and magnitude of natural climate variability, the accuracy of these constructions is dependent largely on the reliability of the proxies. In January 2008, a time series sediment trap was deployed in the northern Gulf of Mexico at 27° 31'N and 90° 21'W in 1200 meters water depth to directly measure the flux and shell chemistry (stable isotope, Mg/Ca ratios) of planktonic foraminifera and sediment geochemistry (carbonate, biogenic opal, organic carbon, terrigenous material) for comparison with concurrent hydrographic and climatic observations. The results of this study will provide improved calibration of standard climate proxies leading to enhanced interpretation and correlation between marine and terrestrial paleoclimate records.

Results will be presented from weekly sediment trap samples collected over a 6-month period from January –July 2008. Preliminary results for the first 3 months indicate total sediment mass and planktonic foraminiferal fluxes are highest in January and February with values up to 0.30 grams m^-2 day^-1 and ~145 shells m^-2 day^-1, respectively. During this winter period, the assemblage is dominated by Globorotalia truncatulinoides, which makes up more than 60% of the assemblage, Globigerina calida, and Pulleniatina obliquiloculata. In the spring, total mass fluxes decrease to 0.07 grams m^-2 day^-1 and foraminiferal fluxes to ~30 shells m^-2 day^-1 as sea surface temperature increases. In addition, the spring assemblage is more diverse and composed of Globorotalia crassaformis (20%), Globigerinoides ruber (pink) (18%), Globigerinoides ruber (white), Globigerina rubescens, Globigerinita glutinata, Globigerinoides sacculifer, and Neogloboquadrina dutertrei.