HR: 1400h
AN: PP43C-04    [Abstracts]
TI: Climate Change during the Last Deglaciation in the lowlands of Central America
AU: * Hodell, D A
EM: hodell@ufl.edu
AF: University of Florida, Department of Geological Sciences, PO Box 112120, Gainesville, FL 32611, United States
AU: Brown, E T
EM: etbrown@d.umn.edu
AF: University of Minnesota - Duluth, Large Lakes Observatory, 2205 E. 5th St., Research Laboratory Building 207, Duluth, MN 55812, United States
AU: Anselmetti, F
EM: flavio@erdw.ethz.ch
AF: ETH-Zurich, Geological Institute Universitatrasse 16 , Zurich, CH-8092, Switzerland
AU: Ariztegui, D
EM: daniel.ariztegui@terre.unige.ch
AF: University of Geneva, Dept de Geologie et Paleontologie 13, Rue des Maraīchers, Geneva, CH-1205, Switzerland
AU: Brenner, M
EM: brenner@ufl.edu
AF: University of Florida, Department of Geological Sciences, PO Box 112120, Gainesville, FL 32611, United States
AU: Curtis, J H
EM: curtisj@ufl.edu
AF: University of Florida, Department of Geological Sciences, PO Box 112120, Gainesville, FL 32611, United States
AU: Gilli, A
EM: agilli@ufl.edu
AF: University of Florida, Department of Geological Sciences, PO Box 112120, Gainesville, FL 32611, United States
AU: Grzesik, D
EM: dustin.grzesik@gmail.com
AF: University of Florida, Department of Geological Sciences, PO Box 112120, Gainesville, FL 32611, United States
AU: Mueller, A D
EM: andreas.mueller@erdw.ethz.ch
AF: ETH-Zurich, Geological Institute Universitatrasse 16 , Zurich, CH-8092, Switzerland
AB: In Feb-March 2006, we recovered 1,327 m of sediment core at seven sites in Lake Peten Itza, northern Guatemala. Preliminary post-drilling research has focused on Site PI-6 located in a water depth of 71 m where three holes were drilled to a maximum depth of 75.9 mblf. Using an ITRAX XRF core scanner at the University of Minnesota - Duluth, we measured a suite of elements between Al and Ba (e.g., Al, Si, P, S, K, Ca, Ti, Mn, Fe, Rb, Sr, Ba) at 0.5-cm resolution from 9.85 to 25.92 mcd in the spliced composite section at Site PI-6. This interval spans the period from the Last Glacial Maximum (24 kyrs ) to just above the Pleistocene/Holocene boundary (~8.3 kyrs). The chronology was derived by linear interpolation between 7 well-ordered radiocarbon dates on terrestrial organic matter. Elemental variations largely reflect relative changes in sediment composition between three dominant components: sulfates, carbonates, and silicates. Sediments deposited during the last glacial maximum (LGM) from ~23 to 18 kyrs were marked by high values of detrital elements (K, Rb, Fe, Ti) reflecting clay deposition in deep water under relatively wet climate conditions. This finding contradicts previous results suggesting that the LGM was dry in the Peten lowlands. From ~18 to 14.7 kyrs, sulfur content is high reflecting deposition of gypsum under arid climate. Within this generally dry interval, a period of very rapidly fluctuating gypsum (S) and clay (K, Rb, Fe, Ti) interbeds occurred between 16 and 15.5 kyrs. Coincident with the start of the Bolling-Allerod at 14.5 kyrs, gypsum deposition ceased and detrital elements (K, Rb, Fe, Ti) increased abruptly and remained relatively high between ~14.7 and 12.8 kyrs, indicating wetter conditions. At the start of the Younger Dryas at 12.8 kyrs, detrital elements (K, Rb, Fe, Ti) declined and S increased reflecting gypsum deposition. Relatively dry conditions persisted until ~10.2 kyr when gypsum deposition ceased and mesic conditions prevailed in the early Holocene. This inferred deglacial sequence from Lake Peten Itza in the lowlands of Central America will be compared with records of ITCZ migration inferred from the Caribbean (Cariaco Basin), meltwater input to the Gulf of Mexico, and polar ice cores from Greenland and Antarctica.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4914 Continental climate records
DE: 4926 Glacial
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly