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.