HR: 1400h
AN: PP43C-08    [Abstracts]
TI: Late Holocene Droughts Recorded in Speleothems From the Maya Lowlands of the Yucatan Peninsula, Mexico
AU: * Endsley, E A
EM: eendsley@d.umn.edu
AF: Department of Geological Sciences, University of Minnesota Duluth, 229 Heller Hall 1114 Kirby Drive, Duluth, MN 55812, United States
AU: Gallup, C D
EM: cgallup@d.umn.edu
AF: Department of Geological Sciences, University of Minnesota Duluth, 229 Heller Hall 1114 Kirby Drive, Duluth, MN 55812, United States
AU: Hodell, D A
EM: hodell@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall PO Box 112120, Gainesville, FL 32601, United States
AU: Curtis, J H
EM: curtisj@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall PO Box 112120, Gainesville, FL 32601, United States
AU: Brenner, M
EM: brenner@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall PO Box 112120, Gainesville, FL 32601, United States
AU: Gentry, C L
EM: cgentry@geology.ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall PO Box 112120, Gainesville, FL 32601, United States
AU: Edwards, R L
EM: edwar001@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 108 Pillsbury Hall 310 Pillsbury Dr S E, Minneapolis, MN 55455, United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 108 Pillsbury Hall 310 Pillsbury Dr S E, Minneapolis, MN 55455, United States
AB: Evidence for Holocene droughts in Mesoamerica exists from numerous paleolimnological studies. Speleothems from the Yucatan Peninsula can be used to help constrain the timing, intensity, and regional extent of these droughts. Late Holocene wet/dry cycles are inferred from the oxygen isotope record of speleothem calcite and the timing is constrained using U/Th dating. In the lowland neotropics, there is a strong negative correlation between δ18O of precipitation and rainfall amount, i.e. the "amount effect." The δ18O of speleothem calcite can then be used as a proxy for the relative amount of past precipitation in the Maya lowlands. A speleothem from Cueva Tzabnah, near Tecoh, Yucatan, Mexico, has a basal date of 2711 ±329 yr BP and a top date of 548 ±61 yr BP, indicating growth during most of the period of Maya prehistory. The 25cm-long speleothem has an average growth rate of 0.12mm/yr, and contains several visible hiatuses indicating cessation of growth, possibly due to drier climate conditions. Oxygen isotopes were measured at 0.5mm intervals, with an average value of -5.24‰. δ18O values increase near the hiatuses in speleothem growth, interpreted as evidence for the presence of drought conditions. These relative increases in δ18O will be dated using U/Th methods to constrain the timing of the drought events. In the top 3mm, the average δ18O value is 2.49‰ greater than the average speleothem δ18O value, and possibly represents drier conditions beginning in the mid-15th century AD consistent with a nearby lake sediment core record from Aguada X'camaal (Hodell et al., 2005). Well-dated drought events during the late Holocene will provide insight into the role that climate may have played in the cultural evolution of the Maya civilization. References: Hodell, D.A., Brenner, M., Curtis, J.H., Medina-Gonzalez, R., Ildefonso-Chan Can, E., Albornaz-Pat, A., Guilderson, T.P., 2005. Climate change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research 63, 109-121.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1120 Isotopic disequilibrium dating
DE: 1637 Regional climate change
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4958 Speleothems
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly