HR: 0800h
AN: GP21B-05    [Abstracts]
TI: Multi-proxy analyses of kasten cores and surface samples from the Joinville-d'Urville Trough, Northeastern Antarctic Peninsula: Results and correlation with the Western Antarctic Peninsula
AU: * Perez, R B
EM: rachelpez@yahoo.com
AF: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Avenue, Montclair, NY 07043, United States
AU: Brachfeld, S
EM: brachfelds@mail.montclair.edu
AF: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Avenue, Montclair, NY 07043, United States
AU: Gorring, M L
EM: gorringm@mail.montclair.edu
AF: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Avenue, Montclair, NY 07043, United States
AU: Domack, E W
EM: edomack@hamilton.edu
AF: Department of Geology, Hamilton College, 198 College Road, Clinton, NY 13323, United States
AU: Leventer, A
EM: aleventer@mail.colgate.edu
AF: Department of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346, United States
AU: Maritz, J
EM: jmaritz@mail.colgate.edu
AF: Department of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346, United States
AU: Passchier, S
EM: passchiers@mail.montclair.edu
AF: Department of Earth and Environmental Studies, Montclair State University, 1 Normal Avenue, Montclair, NY 07043, United States
AB: Two sediment cores, LMG04-04 KC16 and KC3, an expanded and a condensed section, respectively, were recovered from a sediment drift within the Joinville-d'Urville Trough on the northeastern Antarctic Peninsula (AP), in approximately 750 m water depth. Both cores show a two-part magnetic susceptibility profile: the upper section shows regularly spaced highs and lows, followed by a large (>50%) amplitude drop. The susceptibility profiles of these two cores are similar to those found on the western side of the AP. The purpose of this study is to determine whether the same processes drive magnetic susceptibility on both sides of the AP. Major element geochemical analyses show that susceptibility is positively correlated with Ca, Al, Mn, Mg, and Ti, and is inversely correlated with Fe/Ti. Paleoproductivity, as indicated by Si/Al and Ba/Al ratios, has no consistent relationship with susceptibility. These parameters alternately show direct, inverse, or no correlation. P/Al ratios were uniform downcore. The lack of consistent correlation between Si/Al and susceptibility may indicate that siliceous phytoplankton productivity is not a main driving factor, although there is a weak positive correlation between % benthic diatoms and susceptibility peaks. Susceptibility peaks and troughs in KC16 and KC3 were sampled for low-temperature magnetic susceptibility. All samples exhibit a magnetic order/disorder transition at ~117 K, which we interpret as the magnetite Verwey transition. The Verwey transition peak is less prominent below the susceptibility drop in KC3. Particle size analyses of KC16 and KC3 show a bimodal distribution of grain sizes. Medium to fine silt-sized particles dominate in both cores, as well as in surface samples collected across the sediment drift. Both cores contain ~20-54% very fine sand above the susceptibility drop, but percentages in the fine sand region and larger are complicated by the presence of macroalgal detritus. Unlike the western AP susceptibility profiles, hysteresis measurements from KC16 show no relationship between magnetic grain size and susceptibility. We speculate that paramagnetic detrital minerals may be an important driver of the susceptibility profile on the east side, where biogenic silica is not a significant component of the sediment. XRD and SEM analyses are in progress in order to study the bulk mineralogic assemblage and investigate the source of the inverse relationship between susceptibility and Fe/Ti.
DE: 1051 Sedimentary geochemistry
DE: 1512 Environmental magnetism
DE: 1540 Rock and mineral magnetism
DE: 3022 Marine sediments: processes and transport
DE: 9310 Antarctica (4207)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly