PALEOMAGNETIC ANALYSES FROM THE SHADRILL MAXWELL BAY SITE, SOUTH SHETLAND ISLANDS, ANTARCTIC PENINSULA

Core NBP05-02 1B from Maxwell Bay, South Shetland Islands recovered a 108 m sedimentary record dating between 14.1-14.8 ka. The core is composed of silty-clay lithology and has a calcite based radiocarbon chronology, making this an ideal site to reconstruct an independently dated record of paleosecular variations (PSV) and relative paleointensity (RPI). Anisotropy of magnetic susceptibility (AMS) was measured to assess the fabrics of the core prior to paleomagnetic analyses. The interval 0-72 mbsf displays a normal sedimentary fabric with K_min inclination values nearly vertical and K_int, and K_max distributed within the bedding plane. Below 72 mbsf, we observed fabrics with shallow K_min axes. This may be indicative of drilling disturbance. Samples were analyzed for magnetic hysteresis ratios saturation remanence normalized by saturation magnetization (M_r/M_s) and coercivity of remanence normalized by coercivity (H_cr/H_c). The M_r/M_s values range from 0.122 to 0.06 and H_cr/H_c values range from 3.36 to 6.10, which falls in the pseudo-single-domain region and upper left corner of the multidomain region of the Day Plot. There were no differences in the hysteresis ratios between normal and disturbed AMS fabrics. Curie point analyses have identified four different features in the heating curve: ~150°C, ~300°C, ~450°C and ~550°C. These features have been identified as titanium-rich titanomagnetite, a magnetic iron sulfide and titanium-poor titanomagnetite. U-channels were collected for the upper 60 mbsf. Cube samples were collected throughout the core, and exclusively for 60-108 mbsf. Samples were subjected to stepwise alternating field (AF) demagnetization. A low coercivity overprint, likely a drilling or storage overprint was removed at 10-15 mT. The sediments recorded a strong, stable remanent magnetization. Inclinations range from -30° to -80°, with shallow inclinations often correlating with disturbed AMS fabrics. The maximum angular deviation (MAD) values ranges from 1.3° to 5.6°. The variations in the MAD angles do not correlate with type fabric. We ultimately seek to generate PSV and RPI reference curves that can be used to tune and date regional paleoclimate records that lack their own independent chronologic control.