My research is interdisciplinary and collaborative. Together with my students and collaborators I have worked on the following projects.
Woranso-Mille Project , Afar, Ethiopia: The Woranso-Mille Paleoanthropological Research Area is the only site thus far to report hominin diversity between 3.8 and 3.3 million years ago (Ma). Geochemical correlation and radioisotopic dating of volcanic tuffs established highly reliable ages for fossiliferous horizons, making Woranso-Mille one of the best dated mid-Pliocene sites in eastern Africa (attached). Isotopic studies of fossil tooth enamel and soil carbonate intercalated with the tuffs indicated C4 plants were abundant in the area as early as 3.8 Ma and were incorporated into hominin diets. In addition, mapping of the tuffs has yielded constraints on chemical and isotopic variations in related basalts, which document the sources of mantle melting and their relation to continental rifting. Going forward, we aim to reconstruct paleolenvironments along time horizons in order to determine the extent to which the the hominin taxa shared the landscape and to understand the factors that allowed for coexistence of multiple species in a small geographic area.
Miocene Basins in the Altiplano, Bolivia: We are using physical, chemical and biological features of ancient soil profiles to interpret the paleohabitats of native South American mammals and their relation to neo-tropical diversity. Dating and geochemical correlation of tuffs allows us to map the distribution of landscapes across the basin. CWRU undergraduates are undertaking preliminary studies of hydrated glass paleoaltimetry to to determine paleo-elevation and its relation to hypotheses about tectonic uplift.
Lake Erie: The history of Lake Erie since the end of the last ice age is recorded in sedimentary, magnetic, and geochemical properties of long sediment cores we collected from the eastern and central basins. These cores show coordinated changes in magnetic susceptibility, grainsize, carbonate and organic carbon content, and stable isotope composition of shell carbonate at approximately 4000 years BP. The timing of those changes coincides both with a reorganization of drainage patterns in the Great Lakes and the mid-Holocene climate transition, which has been interpreted as the result of a change in atmospheric circulation and the seasonal distribution of rainfall. We are studying the cores from the central and eastern basin in more detail and with new techniques to extend the record and to investigate the impact of hydrologic and climatic change on the health of the lake. Click here for more information.
Nama Basin, Namibia: The terminal Proterozoic Nama Basin of Namibia records some of the most profound climatic, biologic, oceanographic, and tectonic events in the history of the Earth, including severe, possibly global glaciations, the amalgamation of the supercontinent Gondwana, and the evolution of complex animal life. Integrated sequence stratigraphy, carbon isotope chemostratigraphy, and geochemical fingerprinting of ash beds pieced together a detailed, three-dimensional sedimentary record of events important evaluating how sedimentary basins respond to sea level change and tectonic flexure and how the geochemistry of the oceans evolved leading into and coming out of severe glaciations.
Paleozoic marine strata of the mid-continent and Appalachian Basin: These formations are important as reservoirs, sources and seals for fluids. They also record significant transitions in climate and ocean conditions. Ordovician epeiric sea carbonates of the mid-continent U.S. were deposited at the end one of one of the warmest periods in Earth history when shallow seas covered most of the continents. The span the transition into a short-lived ice age, which is distinctive because it developed in the context of high atmospheric CO2 in a greenhouse world. Oceanographic changes transformed the style of carbonate platform development across the epeiric sea, and this in turn has significant implications for the physical character if these strata and how the transport and react with fluids.
Injection of CO2 from point sources, such as power plants, into deep sedimentary formations is one potential way to limit the emissions of greenhouse gases to the atmosphere. My research group is studying the reactions between the injected carbon dioxide and the formation minerals and brines. These reactions influence how much CO2 dissolves in the brine and whether or not the CO2 is converted to stable, immobile carbonate minerals. Mineral-brine-CO2 reactions also can contribute to leaking of CO2 from the aquifer by causing dissolution that expands high-flow-rate escape paths to the surface. Currently we are focusing on the Cambrian Rose Run sandstone, a deep saline aquifer beneath Ohio, Pennsylvania, and West Virginia. Our work includes stratigraphic characterization, geochemical modeling, and mineral-brine-CO2 reaction experiments. The work is funded by the Ohio Coal Development Organization. Click here for more information.
We study microParticle Image Velocimetry and other image capture and analysis techniques to obtain quantitative data on single and multiphase flow through transparent rock models. Along with collaborators at the Department of Energy, West Virginia University, and Purdue University we use these data to test computer simulations of porous flow. This work is funded by the Ohio Coal Development Organization and the Department of Energy. Click here for more information.