HR: 0800h
AN: GC51C-1066    [Abstracts]
TI: Lowland Neotropical Climate Change during the Late Deglacial and Early Holocene
AU: * Hillesheim, M B
EM: mbhilles@ufl.edu
AF: University of Florida, Department of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611 United States
AU: Hodell, D A
EM: dhodell@geology.ufl.edu
AF: University of Florida, Department of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611 United States
AU: Anselmetti, F S
EM: flavio.anselmetti@erdw.ethz.ch
AF: Swiss Federal Institute of Technology, ETH, Geological Institute, Zurich, 8092 Switzerland
AU: Ariztegui, D
EM: daniel.ariztegui@terre.unige.ch
AF: University of Geneva, Institut Forel and Department of Geology, Geneva, 1211 Switzerland
AU: Brenner, M
EM: brenner@geology.ufl.edu
AF: University of Florida, Department of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611 United States
AU: Curtis, J H
EM: curtisj@ufl.edu
AF: University of Florida, Department of Geological Sciences 241 Williamson Hall, Gainesville, FL 32611 United States
AU: Leyden, B W
EM: leyden@chuma1.cas.usf.edu
AF: University of South Florida, Department of Geology, Tampa, FL 33620 United States
AB: The transition from arid glacial to moist early Holocene conditions represented a profound change in lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition ($\sim$11,250 to 7,500 cal yr BP) inferred from sediment cores retrieved in Lake Peten-Itza, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by $\sim$11,250 cal yr BP, but sediment properties indicate that lake level was $>$35 m below modern stage. From 11,250 to 10,350 cal yr BP, in the Preboreal period, lithologic changes in sediments from deep-water cores ($>$50 m below modern water level) indicate several wet-dry cycles that correlate with glacial meltwater pulses into the Gulf of Mexico. After 10,350 cal yr BP, multiple sediment proxies suggest a shift to persistent mesic climate during the early Holocene, with the exception of brief (100-300 yrs) returns to drier conditions at 10,200, 9,400, and 8,000 cal yr BP that were associated with cooling in the North Atlantic and Greenland. Comparison of results from Lake Peten-Itza with other records from the circum-Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period was tightly linked to climate change in the high-latitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores-Bermuda high-pressure system. This mechanism operated on millennial-to-submillennial timescales and responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and deep-water production rates.
DE: 1845 Limnology
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1620 Climate dynamics (3309)
DE: 1650 Solar variability
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting