HR: 1340h
AN: PP43B-1270    [Abstracts]
TI: Paleoclimatic impact on vertebrate activities: a speleothem record from Power Mill Creek Cave, Missouri
AU: * Gao, Y
EM: gaoy@etsu.edu
AF: East Tennessee State University, Department of Physics, Astronomy and Geology, Johnson City, TN 37614, United States
AU: Schubert, B W
EM: schubert@etsu.edu
AF: East Tennessee State University, Department of Physics, Astronomy and Geology, Johnson City, TN 37614, United States
AU: Wang, X
EM: wang0452@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, Minneapolis, MN 55455, United States
AU: Rowe, H D
EM: hrowe@email.uky.edu
AF: University of Kentucky, Department of Earth and Environmental Sciences, Lexington, KY 40506, United States
AU: Buckles, J
EM: zjab67@goldmail.etsu.edu
AF: East Tennessee State University, Department of Physics, Astronomy and Geology, Johnson City, TN 37614, United States
AU: Kaufmann, J E
AF: University of Missouri Rolla, Department of Geosciences and Engineering, Rolla, MO 65409,
AB: Two speleothem samples were collected from Power Mill Creek Cave (PMCC), Missouri, for uranium-series dating at the University of Minnesota and stable isotopic analyses at the University of Kentucky. The speleothem samples found in the cave were attached to the bones of an extinct ground sloth (Megalonyx jeffersonii). A femur was propped up on one stalagmite (PMCC1) and cemented to it by subsequent layers of flowstone. The other stalagmite (PMCC2) formed on top of a scapula. The ages of the speleothem samples range between 52,900 and 660 years old. Very few absolute dates on M. jefferesonii are known from the south-central United States and none of these are associated with paleoclimate data. With high-precision U-Th dates and the unique sample, PMCC1, we can narrow the age range of this M. jeffersonii to be between 42,100 ± 400 and 38,500 ± 500 years ago. In addition, we obtained carbon and oxygen isotope data on sample PMCC1 for a time period between 53 to 35 ka and reconstructed the regional climatic and vegetation changes. In general, climatic oscillations and vegetation changes in this region are consistent with the earlier study from speleothem samples of Crevice Cave, Missouri (Dorale et al., 1998). The midcontinental climate cooled and forest replaced grassland between 55 and 41 ka. Then, the temperature suddenly increased at 37 ka. Preliminary analysis of oxygen isotope oscillation shows that this warming around 37 ka was even more dramatic than that reported in the previous investigation at Crevice Cave. Based on these data, the sloth was living in a forested environment associated with a transitional climate. It is likely that these sudden cooling and subsequent warming changes between 42 and 37 ka had an impact on vertebrate communities in this region. Determining the degree of these impacts requires additional comparisons between well dated vertebrates and climatic records.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1105 Quaternary geochronology
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1807 Climate impacts
DE: 3344 Paleoclimatology (0473, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting