HR: 0800h
AN: PP51C-0622    [Abstracts]
TI: Provenance of Pelagic clay in the Eastern Pacific: Dating the downcore Cenozoic dust record.
AU: * Stancin, A M
EM: astancin@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Gleason, J D
EM: jdgleaso@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Rea, D K
EM: davidrea@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Owen, R M
EM: rowen@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Moore, T C
EM: tedmoore@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Blum, J D
EM: jdblum@umich.edu
AF: University of Michigan, Department of Geological Sciences 1100 N. University Ave., Ann Arbor, MI 48105 United States
AU: Hovan, S A
EM: hovan@iup.edu
AF: Indiana University of Pennsylvania, Geoscience Department Walsh Hall, Room 114 302 East Walk, Indiana, PA 15705 United States
AB: Pacific pelagic sediments provide a temporal and spatial context for mapping changing continental sources of eolian dust during the Cenozoic Era. To "fingerprint" sources of terrigenous sediment, we have examined the 0-5Ma record for ODP and piston core sites using Pb, Sr, and Nd isotopes on pelagic and hemipelagic clay extracts. Q-mode factor analysis revealed three factors accounting for 98.4% of the total isotopic variance. Contour plots of factor loadings indicate these three factors represent: 1) the well-known Asian-derived dust province in the central North Pacific; 2) a North American source (easternmost North Pacific); and 3) South American source (south of the Intertropical Convergence Zone). From this analysis, it appears that the late Cenozoic Asian dust source can be quantitatively differentiated downcore from both North American and South American continental sources in the Pacific realm. Extending the downcore record into the mid-Cenozoic has required fish teeth ⁸⁷Sr/⁸⁶Sr isotope dating of pelagic clays. Piston cores raised by the R/V Ewing in 1997 - EW9709 PC-01, PC-02, PC-04, PC-05, PC-07, PC-11 and PC-14 between 30 degrees North and the equator have been dated by this technique. Combined, these cores cover an age range of 28Ma to present. Isotope analysis of Nd, Sr and Pb in the dust fraction from these cores can be combined with the published records from LL44 GPC-3 and ODP 885/886 to generate a more comprehensive down core record of dust accumulation during the mid-late Cenozoic in the East-Central Pacific. This approach has promise for evaluating changes in long-term atmospheric circulation across major Cenozoic global climate transitions and the paleolatitude of the Intertropical Convergence Zone.
DE: 1029 Composition of aerosols and dust particles
DE: 1040 Radiogenic isotope geochemistry
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 1051 Sedimentary geochemistry
DE: 1165 Sedimentary geochronology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005