Mineralogy,petrography, and oxygen and aluminum-magnesium isotope systematics of grossite-bearing refractory inclusions |
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| Institution: | 1. School of Ocean, Earth Science and Technology, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, USA;2. Geoscience Institute/Mineralogy, Goethe University Frankfurt, Germany;3. Centre for Star and Planet Formation, University of Copenhagen, Denmark;4. Institute of Meteoritics, University of New Mexico, USA;5. Division of Geological and Planetary Sciences, California Institute of Technology, USA;6. Department of Geology, School of Earth and Environment, Rowan University, USA;7. Department of the Geophysical Sciences, The University of Chicago, USA;8. Enrico Fermi Institute, The University of Chicago, USA;9. Chicago Center for Cosmochemistry, USA;1. WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, USA;2. Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 200 Monobe-otsu, Nankoku, Kochi 783-8502, Japan;3. Chemistry Division, Nuclear and Radiochemistry, Los Alamos National Laboratory, MSJ514, Los Alamos, NM 87545, USA;4. Department of Earth and Planetary Science, Graduate school of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan;1. Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA;2. Chicago Center for Cosmochemistry, The University of Chicago, Chicago, IL 60637, USA;3. Robert A. Pritzker Center for Meteoritics and Polar Studies, Field Museum of Natural History, Chicago, IL, USA;4. Department of Geoscience, University of Wisconsin, Madison, WI 53706, USA;5. Division of Earth and Planetary Material Sciences, Faculty of Science, Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan;6. Hawai’i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai’i at Mānoa, Honolulu, HI, USA;7. Korea Polar Research Institute, Incheon 406-840, Republic of Korea;8. Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA;9. Chemistry Division, Nuclear and Radiochemistry, Los Alamos National Laboratory, MSJ514, Los Alamos, NM 87545, USA;1. Center for Meteorite Studies, School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404, USA;2. Hawai‘i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA;3. Leiden University, Huygens Laboratory, Niels Bohrweg 2, 2333 CA Leiden, Netherlands;4. Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015-1305, USA;5. Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, 10th & Constitution Avenue NW, Washington, DC 20560-0119, USA;6. Department of Geology, School of Earth & Environment, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, USA;7. Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA;1. Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA;2. Division of Earth-System Sciences, Korea Polar Research Institute, Incheon 21990, Republic of Korea;3. Department of the Geophysical Sciences, Enrico Fermi Institute, and Chicago Center for Cosmochemistry, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637-1433, USA;4. Centre for Star and Planet Formation, Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350, Denmark;1. WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA;2. Chemistry Division, Nuclear and Radiochemistry, Los Alamos National Laboratory, MSJ514, Los Alamos, NM 87545, USA;3. Department of Earth and Planetary Material Sciences, Faculty of Science, Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan;4. Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 200 Monobe Otsu, Nankoku, Kochi 783-8502, Japan;5. Faculty of Science, Ibaraki University, Mito 310-8512, Japan;6. National Institute of Polar Research, Tokyo 190-8518, Japan;7. Kingsborough Community College and Graduate Center, The City University of New York, 2001 Oriental Boulevard, Brooklyn, NY 11235-2398, USA;8. American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA;1. Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131, United States;2. Hawai‘i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, United States;3. Department of the Geophysical Sciences, The University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, United States;4. Chicago Center for Cosmochemistry, The University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, United States;5. Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, United States;6. Geoscience Institute/Mineralogy, Goethe University Frankfurt, Altenhoeferallee 1, 60438 Frankfurt am Main, Germany |
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| Abstract: | Grossite (CaAl4O7) is one of the one of the first minerals predicted to condense from a gas of solar composition, and therefore could have recorded isotopic compositions of reservoirs during the earliest stages of the Solar System evolution. Grossite-bearing Ca,Al-rich inclusions (CAIs) are a relatively rare type of refractory inclusions in most carbonaceous chondrite groups, except CHs, where they are dominant. We report new and summarize the existing data on the mineralogy, petrography, oxygen and aluminum-magnesium isotope systematics of grossite-bearing CAIs from the CR, CH, CB, CM, CO, and CV carbonaceous chondrites. Grossite-bearing CAIs from unmetamorphosed (petrologic type 2―3.0) carbonaceous chondrites preserved evidence for heterogeneous distribution of 26Al in the protoplanetary disk. The inferred initial 26Al/27Al ratio (26Al/27Al)0] in grossite-bearing CAIs is generally bimodal, ?0 and ?5×10?5; the intermediate values are rare. CH and CB chondrites are the only groups where vast majority of grossite-bearing CAIs lacks resolvable excess of radiogenic 26Mg. Grossite-bearing CAIs with approximately the canonical (26Al/27Al)0 of ?5×10?5 are dominant in other chondrite groups. Most grossite-bearing CAIs in type 2–3.0 carbonaceous chondrites have uniform solar-like O-isotope compositions (Δ17O ? ?24±2‰). Grossite-bearing CAIs surrounded by Wark-Lovering rims in CH chondrites are also isotopically uniform, but show a large range of Δ17O, from ? ?40‰ to ? ?5‰, suggesting an early generation of gaseous reservoirs with different oxygen-isotope compositions in the protoplanetary disk. Igneous grossite-bearing CAIs surrounded by igneous rims of ±melilite, Al-diopside, and Ca-rich forsterite, found only in CB and CH chondrites, have uniform 16O-depleted compositions (Δ17O ? ?14‰ to ?5‰). These CAIs appear to have experienced complete melting and incomplete O-isotope exchange with a 16O-poor (Δ17O ? ?2‰) gas in the CB impact plume generated about 5 Ma after CV CAIs. Grossite-bearing CAIs in metamorphosed (petrologic type >3.0) CO and CV chondrites have heterogeneous Δ17O resulted from mineralogically-controlled isotope exchange with a 16O-poor (Δ17O ? ?2 to 0‰) aqueous fluid on the CO and CV parent asteroids 3–5 Ma after CV CAIs. This exchange affected grossite, krotite, melilite, and perovskite; corundum, hibonite, spinel, diopside, forsterite, and enstatite preserved their initial O-isotope compositions. The internal 26Al-26Mg isochrons in grossite-bearing CAIs from weakly-metamorphosed CO and CV chondrites were not disturbed during this oxygen-isotope exchange.HCCJr is grateful to Klaus Keil for all his sound profession counsel and collegial friendship over the years. He has always been willing to talk and has the generous nature of listening and sharing his thoughts freely and constructively. Professor Klaus Keil has been a mentor to and played a key role in the careers of three of the authors of this paper (ANK, KN, and GRH). He has also influenced the careers of the other authors and most of the people who have worked on meteorites over the past 50+ years. We therefore dedicate this paper to Professor Keil and present it in this Special Issue of Geochemistry. |
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| Keywords: | Ca Al-rich inclusions Grossite Oxygen isotopes Carbonaceous chondrites Al-Mg isotope systematics Oxygen isotopic exchange Fluid-rock interaction |
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