Climate and Global Change Atmospheric and Environmental Chemistry Dynamics of the Atmosphere and Other Geophysial Fluids The Paleogeographic Atlas Project High Pressure Geophysics Geochemistry and Cosmochemistry Igneous and Metamorphic Petrology Paleontology and Evolution Other Departments and Related Institutions Affiliated Centers

Igneous and metamorphic petrology have a long tradition of strength at the University of Chicago. The emphasis has generally been on the development and application of tools and techniques through experimental studies of phase equilibria, element partitioning and mineral reactions. We have developed geological thermometers and barometers based on mineral chemistry and stable isotope fractionation, and have applied them to the properties and evolution of the crust and mantle particularly as these are affected by subduction, recycling and igneous activity. Field studies are closely correlated with laboratory experiments and analyses, and involve work in India, China, South and Central America, Hawaii, and the ocean floor: anywhere interesting rocks are found.

The in-house electron probe and scanning electron microscope support standard petrographic studies. Various types of high-pressure, high-temperature apparatus are used for experimental study of phase relations. These are complemented by more specialized analytical techniques, such as ion microprobe measurement of trace element abundances, mass spectrometer measurement of stable isotopes, and infrared spectroscopic measurement of H₂O and CO₂ in igneous melt inclusions. The newest tool is the Advanced Photon Source at nearby Argonne National Laboratory, which provides the world's brightest x-ray source for use in crystal structure studies and in detailed mineralogical investigations.

Several currently active studies focus on the role of volatiles, particularly water and carbon dioxide, in igneous and metamorphic processes. These substances are crucial in determining whether or not volcanic eruptions are explosive. They are also critical in controlling lower-mantle mineral assemblages (granulites and charnockites). They are key components of ore-depositing fluids. Another major study involves ultra-high-pressure metamorphism, in which surficial rocks have been buried in the mantle, then rapidly exhumed. Our studies benefit from coordinated application of multiple approaches including field relations, structural geology and tectonics, as well as geothermometry, geobarometry and geochemistry.

Relevant Faculty include:

• Alfred T. Anderson, Jr., Volcanology (Professor Emeritus)
• Robert N. Clayton, Isotope Geochemistry (Professor Emeritus)
• Lawrence Grossman, Cosmochemistry
• Robert C. Newton, High Pressure and Metamorphic Petrology (retired)
• David Rowley, Tectonics

Overlapping interests are particularly strong with faculty in geochemistry and cosmochemistry and high pressure geophysics and geochemistry. Associated scientists Andrew Davis and Ian Steele, and Field Museum curator Meenakshi Wadhwa are important in-house collaborators.