HR: 0800h
AN: PP51A-0183    [Abstracts]
TI: Late Quaternary Paleoceanography of the Mendeleev Ridge, Central Arctic Ocean: Planktonic Foraminiferal Composition and Stable Isotopy
AU: * Adler, R
EM: adler.66@osu.edu
AF: Byrd Polar Research Center, 1090 Carmack Rd., Columbus, OH 43210, United States
AU: * Adler, R
EM: adler.66@osu.edu
AF: School of Earth Sciences, Ohio State University, Columbus, OH 43210, United States
AU: Polyak, L
EM: polyak.1@osu.edu
AF: Byrd Polar Research Center, 1090 Carmack Rd., Columbus, OH 43210, United States
AU: Ortiz, J
EM: jortiz@kent.edu
AF: Dept. of Geology, Kent State University, Kent, OH 44242, United States
AU: Grottoli, A
EM: grottoli.1@osu.edu
AF: School of Earth Sciences, Ohio State University, Columbus, OH 43210, United States
AU: Kaufman, D
EM: darrell.kaufman@nau.edu
AF: Dept. of Geology and Environmental Sciences, Northern Arizona University, Flagstaff, AZ 86011, United States
AB: Mendeleev Ridge is located between the two major circulation systems of the Arctic Ocean, the Beaufort Gyre and the Transpolar Drift, thus offering a valuable sedimentary archive for investigating paleoceanographic changes. We perform a detailed investigation of a HOTRAX05 sediment core HLY0503-08JPC (79°35.6'N, 172°30.1'W, 2792 mwd, length 12m) from the Mendeleev Ridge flank that provides millennial to century scale resolution for upper Quaternary sediments. The core has been logged for VIS Diffuse Spectral Reflectance and XRF, u-channeled for paleomagnetic analyses and coninutously sampled at 1cm sample width. The washed >63um sediment fraction is being analyzed for planktonic foraminiferal content and stable isotopic composition. Age constraint for the upper Quaternary record is provided by AMS ¹⁴C dates and Amino Acid Racemization measurements from foraminiferal adundance maxima, as well as correlation with established Arctic Ocean stratigraphies. The brown, faunal rich intervals in the upper to middle Quaternary record correspond to interglacials when the influence of circum-arctic ice sheets on processes in the Arctic Ocean was minimal. Grayish, faunal poor intervals reflect glacial/deglacial environments characterized by discharge of icebergs and meltwater. The later part of the LGM contains a pronounced hiatus, possibly related to the ice cover over the basin at that time. We infer that earlier glaciations may also contain hiatuses, which should result in uneven sedimentation rates. Brown intervals are characterized by high biogenic sediment and high stable isotope values in planktonic foraminiferal tests, especially d¹³C. We presume that these features are related to better ventilation of the halocline from the continental margins at higher sea levels and less ice cover. d¹⁸O record displays prominent minima within glacial intervals, which, together with IRD spikes, indicate discharges of icebergs and meltwater from ice sheets at the Arctic periphery. In particular, sharp d¹⁸O minima in the penultimate glacial unit probably represent pulsed drainage of proglacial lakes in Eurasia.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 3030 Micropaleontology (0459, 4944)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting