HR: 1340h
AN: PP43B-1265    [Abstracts]
TI: A Multi-proxy Approach to Using Cave Sediment Carbon Isotopes for Late Holocene Paleoenvironmental Reconstruction in Florida
AU: * Polk, J S
EM: jspolk@mail.usf.edu
AF: University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, United States
AU: van Beynen, P
EM: vanbeyne@cas.usf.edu
AF: University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620, United States
AB: Carbon isotopes from cave sediments collected from Jennings Cave in Marion County, Florida were analyzed using a multi-proxy approach. Fulvic acids (FAs), humic acids (HAs), black carbon, phytoliths, and bulk organic matter were extracted from the sediments for carbon isotope analysis to determine periods of vegetation change caused by climatic influences during the Late Holocene (~\ 2,800 years BP). The carbon isotope record ranges from -35‰ to -14‰, exhibiting variability of ~\ -21‰, within the different proxies, which indicates changes between C3 and C4 vegetation. This likely indicates changes between a sub-tropical forested environment and more arid, grassy plains conditions. These changes in plant assemblages were in response to changes in available water resources, with increased temperatures and evapotranspiration leading to arid conditions and a shift toward less C3 vegetation (increased C4 vegetation) during the MWP. The cave sediment fulvic acid cabon isotopes record agrees well with ä13C values from a speleothem collected nearby that covers the same time period. Prolonged migration of the NAO and ITCZ affects precipitation in Florida and likely caused vegetation changes during these climatic shifts.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1055 Organic and biogenic geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting