Much of what we know about past climate change comes from the oxygen
isotopic composition of benthic foraminifera. Although this proxy outlines
large scale climate change, the absolute magnitude of glaciation and the
relationship between glaciation events and ocean temperatures cannot be
determined uniquely from this proxy. If oxygen isotope measurements are
paired with an independent temperature proxy, such as foraminiferal Mg/Ca
ratios, then it should be possible to constrain the temperature effect and
obtain a refined view of the isotopic composition of seawater through time,
which varies largely due to the growth and decay of continental ice sheets.
Mg/Ca paleothermometry, however, is limited by uncertainties related to the
cycling of these cations through seawater and most studies have focused on
the Pleistocene in order to avoid ambiguities related to temporal changes in
seawater Mg/Ca ratios. With this in mind, I explore the application of
foraminiferal Mg/Ca paleothermometry in refining the early Cenozoic history
of Antarctic glaciation. Although not the focus of this particular talk, I
was a shipboard scientist on ODP Leg 177, Southern Ocean Paleoceanography.