Investigating Planetary Magnetic Fields : 1. Paleosecular Variation and Relative Paleointensity Curves From Maxwell Bay, Antarctica 2. Rock Magnetic and Remanence Properties of Natural and Synthetic Martian Basalts

• Main Author: Shah, Deepa
• Format: Text
• Language: unknown
• Published: Montclair State University Digital Commons 2013
• Subjects: Earth Sciences; Environmental Sciences; South Shetland Islands; Yamato; Maxwell Bay; Curie Point; Antarc*; Antarctica
• Online Access: https://digitalcommons.montclair.edu/etd/977; https://digitalcommons.montclair.edu/context/etd/article/1979/viewcontent/Shah_Thesis_2013_Redacted.pdf

This thesis study investigates two individual projects to determine the paleomagnetic records from sediment core NBP0502-1B from Maxwell Bay Antarctica and SNC Martian meteorite Yamato-908459. Core NBP0502-1B from Maxwell Bay, South Shetland Islands, recovered a 108 m sedimentary record dating between 14.1-14.8 ka. The core has a silty-clay lithology and a calcite based radiocarbon chronology, making this an ideal site to reconstruct an independently dated record of paleosecular variation (PSV) and relative paleointensity (RPI). The interval 0-72 mbsf displays a normal sedimentary fabric, with Kmjn inclination values nearly vertical and Kint and Kmax distributed within the bedding plane. Below 72 mbsf, we observed fabrics with shallow Kmin axes, which may have been caused by deposition on an inclined seafloor. Samples were analyzed for magnetic hysteresis ratios: saturation remanence normalized by saturation magnetization (Mr/Ms) and coercivity of remanence normalized by coercivity (Hcr/Hc). The samples plot in the pseudo-single domain (PSD) region and to the right of the PSD region of the Day Plot. There were no differences in the hysteresis ratios between normal AMS fabrics and those from below 72 mbsf. Curie point analyses have identified four different features in the heating curve; these features have been tentatively identified as titanium-rich titanomagnetite, a magnetic iron sulfide, and two titanomagnetites, with moderate Ti and poor Ti content. Scanning electron microscope analysis supports the Curie point measurements. Samples were also 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 values between the u-channels and paleomagnetic cubes range from 36.6° to -89.9°, with shallow inclinations often correlating with but not limited to AMS fabrics with non-vertical Kmin values. The maximum angular deviation (MAD) values ...