HR: 1330h
AN: PP23B-04    [Abstracts]
TI: Rapid Climatic Change at the End of the Last Glacial as Determined from Palynological Analysis of Sediments from the Cariaco Basin, Venezuela
AU: * Delusina, I
EM: delusina@geology.ucdavis.edu
AF: Dept. of Geology, University of California-Davis, Davis, CA 95616 United States
AU: Peterson, L C
EM: lpeterson@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AU: Spero, H
EM: spero@geology.ucdavis.edu
AF: Dept. of Geology, University of California-Davis, Davis, CA 95616 United States
AB: We report the first palynological study of a deep marine sediment core from the anoxic Cariaco Basin, off the coast of Venezuela. The Cariaco Basin acts as a natural sediment trap for rapidly accumulating sediments of marine and terrestrial origin. This situation creates favorable conditions for studying short-term paleoenvironmental change. Our pollen analyses indicate unique pollen assemblages which mirror the complex altitudinal zonation of coastal vegetation and its dynamics. The pollen analyses encompass the interval from 3 to 9 m in core MD03-2620, spanning the Glacial/Holocene transition and including the Younger Dryas and the beginning of the Preboreal. Our data indicate large changes during the time of Heinrich event 1 (ca 16-14 Kyr BP) with high arboreal/nonarboreal pollen ratios (2/8) and a dominance of wormwood changing to a cereals/sedge community. Another characteristic of this interval is the lowest pollen concentration, indicating the coldest and driest observed conditions. The disappearance of mangrove pollen at the time of the coldest episodes provides additional indirect evidence for the deterioration of climate conditions and for a drop in sea level. Maximum forest vegetation is found from the middle of the Bolling/Allerod and the middle of the Younger Dryas. This is followed by a similar, though less intense, interval of cooling between the Younger Dryas and the Preboreal. Variations in both the diversity of species and the pollen concentration correlate well with changes in sediment color and with the marine oxygen isotope record.
DE: 3022 Marine sediments--processes and transport
DE: 3344 Paleoclimatology
DE: 4243 Marginal and semienclosed seas
DE: 9360 South America
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2005 Joint Assembly