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Unformatted text preview: American Mineralogist, Volume 93, pages 16931720, 2008 0003-004X/08/11121693$05.00/DOI: 10.2138/am.2008.2955 1693 REVIEW PAPER Mineral evolution R OBERT M. H AZEN , 1, * D OMINIC P APINEAU , 1 W OUTER B LEEKER , 2 R OBERT T. D OWNS , 3 J OHN M. F ERRY , 4 T IMOTHY J. M C C OY , 5 D IMITRI A. S VERJENSKY , 4 AND H EXIONG Y ANG 3 1 Geophysical Laboratory, Carnegie Institution, 5251 Broad Branch Road NW, Washington, D.C. 20015, U.S.A. 2 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A OE8, Canada 3 Department of Geosciences, University of Arizona, 1040 East 4 th Street, Tucson, Arizona 85721-0077, U.S.A. 4 Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, U.S.A. 5 Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A. ABSTRACT The mineralogy of terrestrial planets evolves as a consequence of a range of physical, chemical, and biological processes. In pre-stellar molecular clouds, widely dispersed microscopic dust particles contain approximately a dozen refractory minerals that represent the starting point of planetary mineral evolution. Gravitational clumping into a protoplanetary disk, star formation, and the resultant heat- ing in the stellar nebula produce primary refractory constituents of chondritic meteorites, including chondrules and calcium-aluminum inclusions, with ~60 different mineral phases. Subsequent aque- ous and thermal alteration of chondrites, asteroidal accretion and differentiation, and the consequent formation of achondrites results in a mineralogical repertoire limited to ~250 different minerals found in unweathered meteorite samples. Following planetary accretion and differentiation, the initial mineral evolution of Earths crust depended on a sequence of geochemical and petrologic processes, including volcanism and degassing, fractional crystallization, crystal settling, assimilation reactions, regional and contact metamorphism, plate tectonics, and associated large-scale fluid-rock interactions. These processes produced the first continents with their associated granitoids and pegmatites, hydrothermal ore deposits, metamorphic terrains, evaporites, and zones of surface weathering, and resulted in an estimated 1500 different 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. Biological processes began to affect Earths surface mineralogy by the Eoarchean Era (~3.853.6 Ga), when large-scale surface mineral deposits, including banded iron formations, were precipitated under the influences of changing atmospheric and ocean chemistry. The Paleoproterozoic Great Oxida- tion Event (~2.2 to 2.0 Ga), when atmospheric oxygen may have risen to &gt;1% of modern levels, and the Neoproterozoic increase in atmospheric oxygen, which followed several major glaciation events,...
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