Research Areas: Paleoclimatology and Paleoceanography

1. Aqueous Geochemistry
2. Environmental and Theoretical Geochemistry
3. Mineral Physics and Petrology
4. Paleoecology
5. Paleoclimatology and Paleoceanography
6. Planetary Science    
7. Sedimentology and Stratigraphy
8. Seismology
9. Space Geodesy
10. Tectonics and Structural Geology

Brad Sageman's work on the use of Fourier techniques to analyze the sedimentary expression of orbital forcing of climate has led to some interesting recent projects. Sageman advised recently graduated Ph.D. student Steve Meyers on the development of several new spectral techniques, such as an evolutive harmonic method for deconvolving high resolution sedimentation rates and identifying hiatuses in rhythmically bedded sequences, as well as on a study of the latitudinal variations in orbital cyclicity during the LateCenomanian-EarlyTuronian. An outgrowth of these studies was the development of a new geochemical model for organic matter burial which, applied to the data records of Oceanic Anoxic Event II in the Western Interior basin, resulted in a new interpretation for oceanographic and biogeochemical processes. Sageman is also pursuing geochemical studies of the roles of terrestrially derived vs. recycled nutrients in ancient epeiric seas, and their relative effects on paleoproductivity.

Abraham Lerman addresses global change and biogeochemical cycles at geological time scales. He studies how the global biogeochemical cycles of carbon, nitrogen and phosphorus work and respond to global climate and other environmental changes.

Matthew Hurtgen's research integrates elemental abundances, stable isotopes, and sedimentological data to investigate the biogeochemical cycling of sulfur, carbon, iron, and oxygen in sediments as old as 2.7 billion years and as recent as today. Most notably, Dr. Hurtgen's research centers on the biogeochemical cycling of sulfur in the late Neoproterozoic--a period encompassing global glaciations that may have endured for tens of millions of years (snowball Earth hypothesis), a significant increase in oxygen concentrations in the coupled ocean-atmosphere system, and the evolution of multi-cellular (metazoan) life. Ongoing efforts focus on the dynamics and internal cycling of sulfur within the marine system at both local and global scales and uses both the sulfur and oxygen isotope composition of sulfate-bearing minerals and phases in ancient carbonates. These studies span nearly all of Earth history and include (but are not limited to) the late Archean, Neoproterozoic, Cambrian, Ordovician, Triassic, Cretaceous and Plio-Pleistocene.

Francesca Smith works on reconstructing past terrestrial climates using the compound-specific isotope signature of ancient organic molecules, or biomarkers. Recent analytical developments have facilitated measurement of hydrogen isotope ratios of individual lipid biomarkers, and have sparked considerable interest in the potential for these isotope ratios to record paleohydrologic conditions. To interpret these isotope records requires an understanding of the factors that determine the isotope signatures in living plants. Smith uses the hydrogen isotope ratio of modern plant lipids from both natural and greenhouse environments to develop mechanistic models of the environmental and leaf anatomical controls on hydrogen isotope fractionation in plant lipids. Using these models, she can better constrain interpretations of paleohydrologic change in the geologic past. For example, she is applying these models to characterizing the hydrologic changes associated with the Paleocene-Eocene Thermal Maximum, the warmest period in the Cenozoic, and valuable analog to future global warming.