| The objectives of climate change research are to record its variations through time and to elucidate possible mechanisms that mediate those variations. The distribution of major and trace elements in marine sediment is a powerful indicator of changes in biological production and terrigenous parameters, both of which respond to climate forcing. This dissertation critically assesses the potential of excess sedimentary aluminum (Al) as a proxy for export production in the equatorial Pacific Ocean, and examines a geochemical record of millennial-scale change in a Southern Ocean sedimentary sequence spanning 9000 years.; Aluminum and titanium (Ti), while typically considered tracers of terrigenous matter, together have a secondary role as a proxy for export production in regions with high biogenic flux and low terrigenous input, like the equatorial Pacific. Here, bulk sedimentary ratios of Al to Ti (Al/Ti) are unusually high due to scavenging of dissolved Al, resulting in excess Al not attributable to terrigenous sources. Sequential extractions reveal that Al and Ti exhibit systematic preferences toward specific sedimentary fractions. In samples with high bulk Al/Ti, the Al is in the oxide fraction and the Ti is in the organic fraction. In samples with low Al/Ti, the Al and Ti are in the residual fraction. These results prove that there is scavenged Al and Ti in sediments, and that in samples with <3% terrigenous matter, Al/Ti can be used to monitor export production.; The West Antarctic Peninsula is an ideal region for millennial-scale climate change research due to its location in one of Earth's most dynamic climate systems. Geochemical records from the Palmer Deep reflect an abrupt change in terrigenous provenance, terrigenous accumulation, nutrient utilization, and biological production that occurred 3500 years before present. Prior to this time, there was enhanced productivity and delivery of Ti-enriched material to the Palmer Deep, which is probably related to ice-free conditions and restructured shelf hydrography. Superimposed on the 9000-year record are high-frequency 400- and 200-year cycles. Possible forcing mechanisms include greater glacial and sea-ice influences, reduced wind shear, or changing oceanographic frontal positions, which may be externally forced by solar irradiance. |
