HR: 1340h
AN: OS33A-0578    [Abstracts]
TI: Holocene and Glacial Variability of the Hydrologic Cycle in the Tropical Atlantic: Evidence from the Cariaco Basin
AU: * Dulski, P
EM: dulski@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Section 3.3, Telegrafenberg, Potsdam, 14473 Germany
AU: Haug, G H
EM: haug@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Section 3.3, Telegrafenberg, Potsdam, 14473 Germany
AU: Peterson, L C
EM: lpeterson@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacher Causeway, Miami, FL 33149 United States
AB: Climate variability in the Central American tropics is largely forced by changes in the intensity of the Hadley circulation and the strength and position of the Intertropical Convergence Zone (ITCZ). The two most direct consequences of seasonal ITCZ motion for Cariaco Basin and its sediments are the pronounced alternation between the upwelling that occurs in the winter-spring and the increased river runoff that takes place in the summer-fall. This seasonal contrast, coupled with the lack of bioturbation during anoxic phases of deposition in the basin, has produced a high deposition rate (ca. 30 to $>$150 cm/kyr). Sediment sequence in most portions consisting of mm-scale, annually-paired plankton-rich biogenic laminae and terrigenous detrital-rich laminae. The built-in seasonal clock that results from ITCZ movement has allowed development of annually-resolved chronologies over intervals where laminae are distinct enough to reliably count yielding nearly unparalleled temporal resolution for a marine sequence. In a series of recent papers, we have utilized measurements of sedimentary Ti and Fe contents as proxies for the total terrigenous fraction of Cariaco Basin sediments. Downcore variations in Ti and Fe have been adopted as indices of past regional hydrologic change, with higher values interpreted to reflect increased rainfall, river discharge, and terrigenous sediment delivery to the basin. Bulk Ti and Fe and other major element patterns in sediment recovered from IMAGES core MD03-2621 and Ocean Drilling Program (ODP) Hole 1002C were measured at a 50 to 500 um spacing, which reflects a temporal spacing of up to 10 measurements per varve, using a new profiling x-ray fluorescence scanner located at GFZ Potsdam. Here, we present a new data set spanning the Holocene and parts of the last glacial period.
DE: 4267 Paleoceanography
DE: 1050 Marine geochemistry (4835, 4850)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting