Speleothems record environmental conditions during their formation and can be used to
reconstruct paleoclimate trends. These geological formations are made of calcium carbonate that
is deposited as water drips through limestone cave ceilings. Variations in isotopic ratios of
carbon (δ 13 C) and oxygen (δ 18 O) from speleothems, namely stalagmites, are used to determine
rainfall and temperature patterns of the past. This study focuses on a stalagmite record from the
Peruvian Andes that was uranium/thorium dated to an interglacial period during Marine Isotope
Stage (MIS) 9. The δ 13 C and δ 18 O of this stalagmite were compared with glacial index data and
total organic carbon levels (TOC) from a nearby lake sediment core, and deuterium data from the
VOSTOK ice core. The relationship between these four data sets reveals an interglacial period
that was gradually moving into a glacial period. The alignment of this stalagmite’s isotope ratios
with the lake core TOC indicates that these two proxies of paleoclimate could be used in tandem
to reconstruct the rainfall and the amount of ice cover on the planet during glacial-interglacial
cycles.
Primary Speaker
Faculty Sponsors