HR: 1340h
AN: PP43B-1271    [Abstracts]
TI: Interpreting Oxygen Isotope Ratios in Fossil Wood Cellulose
AU: * Richter, S L
EM: richter2@sas.upenn.edu
AF: University of Pennsylvania, Department of Earth & Environmental Science, 240 S. 33rd St. (254B Hayden Hall), Philadelphia, PA 19104-6316, United States
AU: Johnson, A H
EM: ahj@sas.upenn.edu
AF: University of Pennsylvania, Department of Earth & Environmental Science, 240 S. 33rd St. (254B Hayden Hall), Philadelphia, PA 19104-6316, United States
AU: Dranoff, M M
EM: mdranoff@hotmail.com
AF: University of Pennsylvania, Department of Earth & Environmental Science, 240 S. 33rd St. (254B Hayden Hall), Philadelphia, PA 19104-6316, United States
AU: Omar, G I
EM: gomar@sas.upenn.edu
AF: University of Pennsylvania, Department of Earth & Environmental Science, 240 S. 33rd St. (254B Hayden Hall), Philadelphia, PA 19104-6316, United States
AU: LePage, B A
EM: Ben_LePage@URSCorp.com
AF: URS Corporation, 335 Commerce Drive, Suite 300, Fort Washington, PA 19034-2623, United States
AB: We evaluated the strength of relationships among cellulose δ¹⁸O (δ¹⁸O_cel), relative humidity, precipitation δ¹⁸O (δ¹⁸O_ppt) and mean annual temperature (MAT) at the continental scale, and the range of variability in δ¹⁸O_cel associated with site hydrologic conditions and species differences. Additionally, we measured the δ¹⁸O of 45 million to 250 year-old fossil wood cellulose as a potential source of information about paleo-δ¹⁸O_ppt and paleo-temperatures. We compared the crystalline structure of ancient and modern cellulose using XRD. At the oldest localities, MAT estimates derived from the modern relationship between MAT and δ¹⁸O_cel are lower than estimates derived from other biological proxies. Estimates of Pleistocene and Holocene MAT's are close to modern values at those sites. These results are consistent with other findings that the MAT/δ¹⁸O_ppt relationship across North America was not constant throughout the Cenozoic. Paleo-δ¹⁸O_ppt estimates derived from fossil cellulose and the modern relationship between δ¹⁸O_cel and δ¹⁸O_ppt are within the current annual range of δ¹⁸O_ppt values at all locations. These findings provide some evidence that a δ¹⁸O_ppt signal may be retained in wood cellulose over millions of years, and that latitudinal patterns in δ¹⁸O_ppt may not have changed much during the past 45 million years.
DE: 0434 Data sets
DE: 0452 Instruments and techniques
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0466 Modeling
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting