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Date: Wednesday, October 17, 2012
Speaker: Robert M. Hazen, Carnegie Institution of Washington and George Mason University
Time and Location: 1:00 PM, with Q&A to follow; in a 1st floor conference room at the American Center for Physics, 1 Physics Ellipse, College Park, MD-- off River Rd., between Kenilworth Ave. and Paint Branch Parkway.
Abstract: The near-surface environment of terrestrial planets and moons evolves as a consequence of selective physical, chemical, and biological processes—an evolution that is preserved in the mineralogical record. Mineral evolution begins with approximately 12 different refractory minerals that form in the cooling envelopes of exploding stars. Subsequent aqueous and thermal alteration of planetessimals results in the approximately 250 minerals now found in unweathered lunar and meteorite samples. Following Earth’s accretion and differentiation, mineral evolution resulted from a sequence of geochemical and petrologic processes, which led to perhaps 1500 mineral species. According to some origin-of-life scenarios, a planet must progress through at least some of these stages of chemical processing as a prerequisite for life. Once life emerged, mineralogy and biology coevolved and dramatically increased Earth’s mineral diversity to>4000 species.
Sequential stages of a planet’s near-surface evolution arise from three primary mechanisms: (1) the progressive separation and concentration of the elements from their original relatively uniform distribution in the presolar nebula; (2) the increase in range of intensive variables such as pressure, temperature, and volatile activities; and (3) the generation of far-from-equilibrium conditions by living systems. Remote observations of the mineralogy of other terrestrial bodies may thus provide evidence for biological influences beyond Earth.
Recent studies of mineral diversification through time reveal striking correlations with major geochemical, tectonic, and biological events, including large-changes in ocean chemistry, the supercontinent cycle, the increase of atmospheric oxygen, and the rise of the terrestrial biosphere.
Biography: Robert M. Hazen, Senior Staff Scientist at the Carnegie Institution’s Geophysical Laboratory and Clarence Robinson Professor of Earth Science at George Mason University, received the B.S. and S.M. in geology at the Massachusetts Institute of Technology (1971), and the Ph.D. at Harvard University in earth science (1975). He is author of 380 scientific articles and 24 books, including Genesis: The Scientific Quest for Life’s Origin and The Story of Earth. The Past President of the Mineralogical Society of America, Hazen’s recent research focuses on the role of minerals in the origin of life, the co-evolution of the geo- and biospheres, and the development of complex systems. He is also Principal Investigator of the Deep Carbon Observatory, a 10-year project to study the chemical and biological roles of carbon in Earth’s interior. Hazen is active in presenting science to nonscientists through writing, radio, TV, public lectures, and video courses. In October 2010 Hazen retired after a 40-year career as a professional symphonic trumpeter.