Areas: Paleoclimatology and Paleoceanography
1. Aqueous Geochemistry
2. Environmental and Theoretical
3. Mineral Physics and Petrology
5. Paleoclimatology and Paleoceanography
6. Planetary Science
7. Sedimentology and Stratigraphy
9. Space Geodesy
10. Tectonics and Structural Geology
Paleoclimatology and Paleoceanography
's stratigraphic research includes studies of the sedimentary expression of orbital forcing of climate. Most of this work has focused on the rhythmic shale-carbonate facies of the Cretaceous Western Interior basin in the United States. Two recent Ph.D. theses were focused on this subject: Steve Meyers, now faculty at University of WI-Madison, worked on the Cenomanian-Turonian strata of the Greenhorn Formation and was responsible for developing several new spectral techniques, including evolutive harmonic analysis and average spectral misfit. Rob Locklair, now a geologist at Chevron, worked on the Conicacian-Santonian strata of the Niobrara Formation and his project fostered collaboration with industry colleagues on the shale gas potential of the Niobrara. Both studies sought to develop high resolution time scales for fine-grained, organic-carbon rich facies in order to improve the power of geochemical proxy data by making possible calculation of mass accumulation rates. Sageman is currently collaborating with Meyers and his UW colleague Brad Singer, an Ar-Ar geochronologist, on a project to integrate new radioisotope dates with floating astronomical time scales in order to refine and improve the Cretaceous time scale.
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.