George Gehrels

Photo of George Gehrels




George Gehrels

University Distinguished Professor 
Associate Department Head
Tectonics and Geochronology




My research focuses on the tectonic evolution of continental margins, and on developing geochronologic tools to study tectonic processes. Current field-oriented research projects include studies of the:

  • tectonic evolution of western North America, including processes of terrane accretion, subduction-related magmatism, sediment dispersal and accumulation, and translation of crustal fragments along the continental margin
  • patterns of sediment generation, dispersal, and accumulation in the interior of North America, from the Archean to the present
  • evolution of the Himalaya-Tibet Plateau orogenic system, especially the role of Paleozoic tectonism in setting the stage for orogenic processes related to India-Asia collision
  • Paleozoic through present-day evolution of the Andean margin of South America

Geochronologic research is conducted in the Arizona LaserChron Center, which is funded by the National Science Foundation to serve as a national center for geochronologic research. The ALC includes a LA-SC-ICPMS system that is dedicated to U-Th-Pb geochronology/thermochronology, a LA-MC-ICPMS system that is used mainly for Hf isotope geochemistry, and a Scanning Electron microscope for imaging and chemical analysis. My role is to oversee day-to-day operation of the ALC, assist visiting researchers with acquisition and interpretation of data, and help drive the development of new geochronologic methods and applications. Information about the ALC is available at

The main courses that I teach include Physical Geology (Geos251) and Oceanography (Geos 212).

Physical Geology is the entry-level course for Geosciences majors, and covers a broad range of topics in Physical and Historical Geology. The course includes a weekly lab session that includes hands-on work with minerals, rocks, fossils, and maps. Students also attend three one-day field trips on weekends. Enrollment is generally between 100 and 150 students.

Oceanography is a General Education course for students who are not majoring in science. The course is divided into three sections that focus on (1) the nature and origin of ocean basins (plate tectonics, volcanoes, earthquakes, sea-floor sediments, seawater chemistry), (2) dynamic processes in the oceans (waves, currents, tides, weather, climate), and (3) marine biology (basic aspects of life, highlights of coastal, open-ocean, and deep-sea communities, impact of human activities). Enrollment is typically 600 students in a lecture section and an additional 200 students in an on-line section.

Additional courses that I have taught include Stratigraphy, Structural Geology, Tectonic Evolution of Western North America, Geology of Arizona, Regional Structural Geology, and Geochronology.

Research Projects

Recent CV

Office: Gould-Simpson Bldg. 529
Phone: 520-349-4702
Fax: 520-621-2672