T. Mark Harrison stands as a preeminent geochemist whose distinguished career has fundamentally shaped our understanding of Earth's evolution. He currently holds the position of Professor Emeritus and Distinguished Research Professor of Geochemistry in the Department of Earth, Planetary and Space Sciences at the University of California, Los Angeles. Harrison received his B.Sc.(Hons.) from the University of British Columbia in 1977 and completed his Ph.D. at the Australian National University in 1981, followed by a postdoctoral fellowship at the Carnegie Institution of Washington. After eight formative years at the State University of New York at Albany where he advanced from assistant to full professor, he joined UCLA in 1989 and has maintained his scholarly home there ever since, with a notable interlude as Director of the Research School of Earth Sciences at ANU from 2001 to 2006.
Harrison's pioneering research has revolutionized multiple aspects of Earth sciences through groundbreaking methodological innovations and paradigm-shifting discoveries about our planet's earliest history. He commissioned the first high-resolution ion microscope in his UCLA laboratory and established himself as a pioneer of 40Ar/39Ar thermochronology, creating essential tools for dating geological events. His work on the tectonic evolution of the Tibet-Himalaya orogenic system has provided critical insights into continental collision processes, while his research on the early Earth has documented the earliest known evidence of terrestrial oceans, plate tectonics, and life itself. These discoveries have fundamentally reshaped scientific understanding of Earth's formative periods and continue to inform contemporary research on planetary habitability and evolution.
As a leader in the geosciences community, Harrison's scholarly impact extends far beyond his personal research through numerous prestigious recognitions and his commitment to advancing the field. He has been elected to both the Australian Academy of Science and the U.S. National Academy of Sciences, and holds fellowships in the American Geophysical Union, Geochemical Society, and Geological Society of Australia. Among his many accolades are the Arthur L. Day Medal of the Geological Society of America and the Walter H. Bucher Medal of the American Geophysical Union, recognizing his exceptional contributions to Earth sciences. Now continuing his scholarly work as Professor Emeritus, Harrison remains actively engaged in research and mentorship, with his 2025 lecture series demonstrating his ongoing commitment to advancing geological understanding and inspiring future generations of Earth scientists.
