HR: 0800h
AN: PP51A-0189    [Abstracts]
TI: High Resolution Holocene Paleomagnetic Secular Variation Records From the Alaskan/Chukchi Sea Borderland
AU: * Lisé-Pronovost, A
EM: agathe_lp@hotmail.com
AF: Institut des sciences de la mer de Rimouski (ISMER), 310, allée des Ursulines, C.P. 3300, Rimouski, Qc G5L 3A1, Canada
AU: St-Onge, G
EM: guillaume_st-onge@uqar.qc.ca
AF: Institut des sciences de la mer de Rimouski (ISMER), 310, allée des Ursulines, C.P. 3300, Rimouski, Qc G5L 3A1, Canada
AU: Barletta, F
EM: Francesco.Barletta@UQAR.QC.CA
AF: Institut des sciences de la mer de Rimouski (ISMER), 310, allée des Ursulines, C.P. 3300, Rimouski, Qc G5L 3A1, Canada
AU: Brachfeld, S
EM: brachfelds@mail.montclair.edu
AF: Montclair State University, 1 Normal Avenue, Montclair, NJ 07043, United States
AU: Polyak, L
EM: polyak.1@osu.edu
AF: Byrd Polar Research Center, Ohio State University, Scott Hall Room 108, 1090 Carmack Road, Columbus, OH 43210-1002, United States
AU: Darby, D
EM: ddarby@odu.edu
AF: Dept. of Ocean, Earth, & Atmospheric Sciences, Old Dominion University, OEAS Main Office – OCNPS, 4600 Elkhorn Ave., Norfolk, VA 23529, United States
AB: Magnetostratigraphy is a powerful dating tool for high latitude paleoceanographic studies. In particular, where datable organic material is scarce and/or reservoir effect is unknown, knowledge of regional paleomagnetic variation (PSV) of the Earth's magnetic field can lead to the setting of a robust chronostratigraphy. Two long piston cores (HLY0501-06JPC and HLY0501-08JPC, hereinafter referred as to cores 8JPC and 6JPC, respectively) from the Alaskan/Chukchi sea borderland were collected on board the USCGC Healy as part of the 2005 Healy- Oden Trans-Arctic Expedition (HOTRAX) in order to establish a pan-Arctic Quaternary stratigraphy. A preliminary age model was derived for core 8JPC with 3 AMS ¹⁴C dates performed on pelecypod shells and indicates sedimentation rates greater than 200 cm/ka, whereas CT number, wet bulk density and low-field volumetric magnetic susceptibility allowed the identification of two major sedimentary units within both cores: an upper postglacial unit and a bottom deglacial unit. Here we present new high-resolution paleomagnetic records in order to augment the initial chronology and to correlate the two cores together. The natural remanent magnetization (NRM) was measured on u-channel samples at 1 cm intervals at the new paleomagnetism laboratory of the Institut des sciences de la mer de Rimouski (ISMER). A strong characteristic remanent magnetization has been isolated using progressive alternating field (AF) demagnetization steps between 20 and 70 mT. Component inclinations and declinations were calculated by principal component analysis, revealing that maximum angular deviation values (MAD) are generally lower than 5° and that the inclination of both cores varies around the expected inclination (80.5°) for the latitude of both coring sites based on a geocentric axial dipole (GAD) model. These results suggest that both cores may have preserved coherent PSV. In addition, hysteresis properties measured using a vibrating sample magnetometer (VSM) together with median destructive field values between 10 and 30 mT suggest that low coercivity pseudo single domain (PSD) magnetic grains are the magnetic carriers in the postglacial unit of both cores. The component inclination and declination profiles of both cores will be presented and correlation between them and other emerging paleomagnetic records from the Arctic will be attempted as a first step to construct a regional PSV chronology.
DE: 1520 Magnetostratigraphy
DE: 1522 Paleomagnetic secular variation
DE: 1560 Time variations: secular and longer
DE: 3002 Continental shelf and slope processes (4219)
DE: 9315 Arctic region (0718, 4207)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting