University of Wisconsin–Madison

Geochemistry

 

Kita, chondrules.
Chondrules from an ordinary chondritic meteorite. F.O.V. ~5mm. Image: N. Kita.

The fundamental theme underlying research in the Geochemistry and Petrology group is to understand the processes responsible for the distribution and interaction of chemical species, minerals, and rocks comprising the solid earth, hydrosphere, atmosphere and biosphere. Research in each group is described below briefly.

Prof. Phil Brown’s research program focuses on understanding the origin of Archean gold and nickel deposits using fluid inclusion observations, electron microprobe and stable isotope analyses, and infrared spectroscopy.

The ICP-MS Isotope Lab group pursues a wide range of geochemical investigations from geochronology to tracing crust and mantle evolution to studying the origin and evolution of life on the early Earth and Mars. The lab is currently co-directed by Prof. Clark Johnson and Dr. Brian Beard, and in Fall 2019, Prof. Annie Bauer will join the group as a co-director. Prof. Bauer’s research focuses on the geochemical record and tempo of atmospheric and oceanic oxygenation, Hadean and Archean crustal production and preservation, and analytical technique development in radiogenic and stable isotope geoscience. Her primary specialties include obtaining geochronological data (U-Pb, Re-Os) and integrating it with stable (S, Fe) and radiogenic isotope systems (Lu-Hf, Sm-Nd, Rb-Sr) to evaluate the chemical evolution of the terrestrial crust, atmosphere, and oceans.

Research in the Wisc Cosmogenic Nuclide Lab, directed by Prof. Shaun Marcott, is focused on determining the age of geomorphic features on Earth’s surface using rare isotopes that are produced by cosmic ray interactions with rocks and minerals, including 10Be and 26Al. A primary focus of the lab is on dating the evolution of Earth’s cryosphere, through the analysis of minerals from Greenland, the eastern U.S., and western North America. Wisc Cosmogenic Nuclide Lab

Prof. Stephen Meyers’ research program primarily addresses three topics: the mechanisms of climate change, the controls on the global carbon cycle, and the measurement of geologic time.  His interdisciplinary approach to investigating these topics integrates data (e.g., geochemical, geophysical, sedimentologic and stratigraphic) with novel modeling and statistical techniques, to unravel the history of the climate system, oceans and geosphere.  Many of these projects involve the X-ray Fluorescence Scanner Laboratory, which Prof. Meyers directs.

Prof. Roden’s research focuses on the biogeochemistry and geomicrobiology of soil and sedimentary environments. Our interdisciplinary program integrates the fields of low-temperature aqueous geochemistry, microbial ecology/physiology/genomics, sediment chemical diagenesis, and ecosystem science. We apply a process-level, experimental approach (including the use of pure culture model systems) to understand the kinetics and mechanistic controls on biogeochemical and geomicrobiological processes in soils and sediments.

Prof. Brad Singer’s research focuses on understanding basic processes that shaped the surficial parts of the Pleistocene and older Earth and the history of the geomagnetic field. 40Ar/39Ar and cosmogenic surface exposure dating methods are used together with geologic field and geochemical data to resolve temporal records of volcanism, glaciation, sedimentation, and reversals of the geodynamo. This research is carried out with the assistance of Dr. Brian Jicha, manager of the WiscAr Lab.

Prof. John Valley’s research interests range from metamorphic and igneous evolution of the crust to sedimentary diagenesis and paleoclimate. Projects generally stress an integrated approach to field-oriented studies, combining stable isotopes, petrology, and other geochemistry. This research is conducted with assistance from Mike Spicuzza who manages the Stable Isotope Laboratory and Dr. Noriko Kita who directs the Ion Microprobe Lab.

Prof. Huifang Xu’s research program focuses on structures and reactivity of nano-minerals, crystal chemistry of feldspars and clay minerals, roles of nanopores in regulating geochemical reactions, and effects of microbes on formation of carbonate minerals using transmission electron microscopy, X-ray & neutron scattering, and computer modeling.