HR: 1340h
AN: U13B-1162    [Abstracts]
TI: Episodes of Midwestern USA Stalagmite Deposition Correlated With Major Stage Boundaries of the Marine Oxygen Isotope Record
AU: * Guzzo, B R
EM: brittany-guzzo@uiowa.edu
AF: University of Iowa, Department of Geoscience 121 Trowbridge Hall, Iowa City, IA 52242, United States
AU: Dorale, J A
EM: jeffrey-dorale@uiowa.edu
AF: University of Iowa, Department of Geoscience 121 Trowbridge Hall, Iowa City, IA 52242, United States
AU: Edwards, R L
EM: edwar001@umn.edu
AF: University of Minnesota, Department of Geology & Geophysics 310 Pillsbury Dr SE, Minneapolis, MN 55455, United States
AU: Shen, C
EM: river@ntu.edu.tw
AF: National Taiwan University, Department of Geosciences, Taipei, 106, Taiwan
AU: Wang, X
EM: wang0452@umn.edu
AF: University of Minnesota, Department of Geology & Geophysics 310 Pillsbury Dr SE, Minneapolis, MN 55455, United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: University of Minnesota, Department of Geology & Geophysics 310 Pillsbury Dr SE, Minneapolis, MN 55455, United States
AB: Using precise U/Th dating techniques with a multi-collector inductively coupled plasma mass spectrometer, we have dated the episodic onset and cessation of calcite deposition in a long-lived stalagmite from Crevice Cave, Missouri USA (38o N, 90o W). Stalagmite CC-99-3-E was recovered as 4 broken pieces and totals approximately 87 cm in length. Top and basal dates show that calcite deposition episodically spanned the time window from ~ 400-120 ka. Four prominent hiatuses can be visually recognized as distinct, opaque white or white/red colored layers in the polished sections which stand in contrast to the yellowish translucent calcite. The timing of non- deposition represented by each hiatus was constrained by milling 100-200 mg sub-samples for dating directly above and below each hiatus. Our preliminary results show that each hiatus is centered on a significant glacial or stadial stage of the marine oxygen isotope record, and that the onset of deposition following each hiatus is centered on a stage boundary. Specifically, the four hiatuses represent the following glacial or stadial periods, following the Marine Isotope Stage (MIS) numbering scheme of Bassinot et al. (1994): MIS 6.6-6.2 with the onset of deposition following at ~ 130 ka, MIS 8.4-8.2 with the onset of deposition following at ~ 245 ka, MIS 8.6, with the onset of deposition following at ~ 290 ka, and MIS 10.4-10.2, with the onset of deposition following at ~ 334 ka. In sum, the pattern of calcite deposition and non-deposition at our inland site follows the overall global pattern of climate change (ice volume linked to insolation forcing) with remarkable fidelity and provides further support for the growing utilization of speleothems for understanding past climate change at continental sites around the world. Furthermore, details of the well-dated calcite deposition record hold promise for continued refinements of our understanding of the specific climatic conditions associated with each MIS. For example, with the exception of MIS 8.6, the periods of non-deposition during MIS's 6.6-6.2, 8.4-8.2, and 10.4-10.2 are all periods of higher global ice volume than MIS 4.2. It is interesting then that MIS 8.6 was a time of non-deposition, and that MIS 4.2, based on several other speleothems in our collection, was a time of prolific calcite deposition. Bassinot, F.C. et al., 1994. The astronomical theory of climate and the age of the Brunhes-Matuyama magnetic reversal. Earth and Planetary Science Letters 126, 91-108.
DE: 4914 Continental climate records
DE: 4926 Glacial
DE: 4940 Isotopic stage
DE: 4958 Speleothems
DE: 4960 Stadial
SC: Union [U]
MN: 2007 Fall Meeting