HR: 1330h
AN: PP22A-1194    [PDF]
TI: Seasonal Variability in Terrigenous Input to the Cariaco Basin, Venezuela.
AU: * Martinez, N C
EM: nahysa@bu.edu
AF: Boston University, Dept. of Earth Sciences, Boston, MA 02215 United States
AU: Murray, R W
EM: rickm@bu.edu
AF: Boston University, Dept. of Earth Sciences, Boston, MA 02215 United States
AU: Thunell, R C
EM: thunell@sc.edu
AF: University of South Carolina, Dept. of Geological Sciences., Columbia, SC 29208 United States
AU: Peterson, L C
EM: l.peterson@miami.edu
AF: University of Miami, Rosenstiel School of Marine Sciences., Miami, Fl 33149 United States
AU: Muller-Karger, F E
EM: carib@seas.marine.usf.edu
AF: University of South Florida, Institute for Marine Remote Sensing. College of Marine Science., St. Petersburg, Fl 33701 United States
AB: Abstract. Previous studies have interpreted variation in Cariaco Basin sediments as representing paleoclimatic changes related to meridional shifting of the Intertropical Convergence Zone and its effect on the relative amount and composition of the terrigenous and biogenic components deposited there. We report results from major, trace, and rare earth element analysis of sediment trap material gathered as part of the CARIACO Time Series Program from two traps (275 m and 425 m, i.e. immediately above and below the redox interface) over a two-year period (November, 1996, to October, 1998). Our goal is to provide insight into Holocene and older paleoceanographic records (e.g., ODP Site 1002) that record climatic changes in terrigenous provenance. We interpret our results along with the main components of opal, calcium carbonate, TOC, and total terrigenous matter, in the context of instrumental records of precipitation, wind stress, and upwelling. Preliminary results show that the detrital component has its highest concentration (weight percent) during rainy periods (wet season), but the terrigenous flux does not show a clear seasonal pattern. Elemental ratios conventionally used as chemical tracers of terrigenous provenance (e.g., Fe/Al, Ti/Al, K/Al, Cr/Al) indicate seasonality in the source of the material. The changes in provenance are decoupled from the changes in terrigenous flux but can be correlated with terrigenous material concentration and with some instrumental records (e.g., SST). The values of Fe/Al and Ti/Al fluctuate between those of Post Archean average Australian Shale (PAAS) and Upper Continental Crust (UC), trending toward PAAS in rainy seasons and UC in dry periods. The seasonal range of Ti/Al is significantly smaller than the glacial-interglacial changes potentially caused by varying input of Saharan eolian material (Yarincik et al., 2000, Paleocean., 15, 210-228). The identification and quantification of the potential end-member sources and their seasonal variability will be better constrained once new data from local sources are obtained.
DE: 1045 Low-temperature geochemistry
DE: 1050 Marine geochemistry (4835, 4850)
DE: 4835 Inorganic marine chemistry
DE: 4850 Organic marine chemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting