Geochemical Tools and Paleoclimate Clues: Multi-Molecular and Isotopic Investigations of Tropical Marine Sediments and Alpine Ice

Matthew Makou, Ph.D., 2006
Timothy Eglinton, Delia Oppo, Advisors

Recently developed analytical techniques, including gas chromatography coupled with time-of-flight mass spectrometry (GC/TOF-MS), stir bar sorptive extraction (SBSE), and thermal desorption (TD) were used to investigate sedimentary organic matter in a variety of tropical depositional settings.  These novel techniques enabled rapid generation of a high-resolution, multi-molecular record from organic-rich Peru Margin sediments, as well as identification and quantitation of trace amounts of organic matter in alpine ice, from which specific compounds were identified that could be used as paleoclimate proxies for biomass burning.  Additionally, isotopic investigations of vascular plant leaf wax biomarkers were performed in order to infer changes in vegetation surrounding the Cariaco Basin and Peru Margin, as well as delivery of organic matter to them.  Together, these methods promote a holistic understanding of environmental change through analysis of biomarkers from a wide range of sources, while reducing sample preparation and analysis times so that development of high-resolution proxy records becomes feasible.  These organic geochemical analyses proved useful for investigating tropical climate change since the last glacial period.  Peru Margin sterol records revealed parallel millennial-scale variability in El Niño and La Niña behavior throughout the Holocene, which may represent a key part of large-scale tropical climate variability.