Vanadium partitioning between orthopyroxene,spinel and silicate melt and the redox states of mantle source regions for primary magmas |
| |
| Institution: | 1. School of Earth and Ocean Sciences, University of Victoria 3800 Finnerty Rd., Victoria, B.C. V8W 3P6, Canada;1. School of Earth Sciences, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;2. Department of Earth, Ocean and Atmospheric Science and National High Magnet Field Laboratory, Florida State University, Tallahassee, FL, USA;3. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;4. University of Sussex, Brighton, United Kingdom;5. NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;1. U. Chicago, IL, United States;2. Planetary Science Institute, AZ, United States;3. Mount Holyoke College, MA, United States;4. Rutgers U., NJ, United States;1. Department of Geological Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA;2. National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA;3. Department of Geological Sciences, University of Delaware, Penny Hall, Newark, DE 19716, USA;4. Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA;5. Department of Earth and Environmental Sciences, University of Minnesota Duluth, 229 Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, USA;1. Institut für Geowissenschaften, Goethe-Universität, Frankfurt am Main, Germany;2. Department of Applied Geology, Curtin University, Australia;3. Earth Sciences Department, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland;4. Department of Geology, University of Johannesburg, PO Box 524, Auckland Park, 2006, Johannesburg, South Africa;1. Department of Earth Science, MS-126, Rice University, Houston, TX 77005, USA;2. Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA;1. Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, USA;2. Smithsonian Institution, National Museum of Natural History, Washington, DC 20560, USA;3. Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada |
| |
| Abstract: | The partitioning of V between orthopyroxene-liquid and spinel-liquid has been investigated in synthetic and natural mafic and ultramafic compositions as a function of temperature and oxygen fugacity (fO2) at 100 kPa and in one experiment at higher pressure. The purpose of the experiments was to understand redox relationships for V in silicate melts with a view to deriving an empirical oxygen barometer for geochemically altered mafic and ultramafic magmas in the geologic record. Partitioning data for both orthopyroxene-liquid and spinel-liquid show profound changes at an fO2 approximately 3 orders of magnitude below the nickel-nickel oxide (NNO) buffer, suggesting changes in the dominant valence state of V in silicate liquids from V3+ to V4+, near this fO2.The results of the experiments on orthopyroxene-liquid are combined with published data for olivine-liquid and are applied to suites of mafic and ultramafic magmas that have equilibrated with a harzburgite residue in the mantle. The results show that Archean alumina-undepleted komatiites could have formed at fairly high oxygen fugacities, near ΔNNO ～ 0, somewhat higher than Cretaceous komatiites and related picrites in the Caribbean region (between ΔNNO ～ ?1 to ?3), and plume-related picrites from West Greenland (ΔNNO ～ ? 3). Picrites and boninites from convergent margins record the highest fO2’s by this method, (ΔNNO = +1 to +2), consistent with other petrological estimates of their redox states. The approach developed in this study can thus provide estimates for the redox states of altered, mantle-derived magmas in the geological record, to which more conventional methods of oxygen barometry cannot be applied. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
