Formation and destruction of magnetite in CO3 chondrites and other chondrite groups
文献类型：期刊论文
| 作者 | Rubin, Alan E.3,4; Li, Ye1,2,4 |
| 刊名 | GEOCHEMISTRY
 |
| 出版日期 | 2019-12-01 |
| 卷号 | 79期号:4页码:10 |
| 关键词 | CO chondrites Magnetite Chromite Alteration Aqueous alteration Metallic Fe-Ni Metallic Cu |
| ISSN号 | 0009-2819 |
| DOI | 10.1016/j.chemer.2019.07.009 |
| 通讯作者 | Rubin, Alan E.(aerubin@ucla.edu) |
| 英文摘要 | Primitive CO3.00-3.1 chondrites contain similar to 2-8 vol.% magnetite, minor troilite and accessory carbide and chromite; some CO3.1 chondrites have fayalite-rich veins, chondrule rims and euhedral matrix grains. All CO3.00-3.1 chondrites contain little metallic Fe-Ni (0.4-1.2 vol.%). CO3.2-3.7 chondrites contain 1-5 vol.% metallic Fe-Ni, minor troilite, accessory chromite and 0-0.6 vol.% magnetite. Magnetite is formed in primitive CO3 chondrites from metallic Fe by parent-body aqueous alteration, resulting in decreased metallic Fe-Ni and an increase in the proportion of high-Ni metal grains. The paucity or absence of magnetite in CO chondrites of subtype >= 3.2 suggests that magnetite is destroyed during thermal metamorphism; thermochemical calculations from the literature suggest that magnetite is reduced by H-2 and reacts with SiO2 to form fayalite and secondary kamacite. Analogous processes of magnetite formation and destruction occur in other chondrite groups: (1) Primitive type-3 OC have opaque assemblages containing magnetite, carbide, Ni-rich metal and Ni-rich sulfide, but OC of subtype > 3.4 contain little or no magnetite. (2) Primitive R3 chondrites and clasts (subtype less than or similar to 3.5) contain up to 6 vol.% magnetite, but most R chondrites contain no magnetite. The principal exception is magnetite with 9-20 wt.% Cr2O3 in a few R4-6 chondrites. Magnetite grains with high Cr2O3 behave like chromite and are more stable under reducing conditions. (3) CK chondrites average similar to 4 vol.% magnetite with substantial Cr2O3 (up to similar to 15 wt.%); these magnetite grains also are stable against reduction during metamorphism. (4) The modal abundance of magnetite decreases with metamorphic grade in CV3 chondrites. (5) Chromite occurs instead of magnetite in those rare samples classified CR6, CR7 and CV7. |
| WOS关键词 | OXYGEN-ISOTOPE COMPOSITIONS ; CARBONACEOUS CHONDRITES ; METAMORPHIC HISTORY ; CV3 CHONDRITES ; COMPOSITIONAL CLASSIFICATION ; CHEMICAL-COMPOSITIONS ; PRIMITIVE CHONDRITES ; THERMAL HISTORIES ; ORGANIC-MATTER ; OLIVINE |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000500465000004 |
| 出版者 | ELSEVIER GMBH |
| 源URL | [http://libir.pmo.ac.cn/handle/332002/35171]  |
| 专题 | 中国科学院紫金山天文台 |
| 通讯作者 | Rubin, Alan E. |
| 作者单位 | 1.Chinese Acad Sci Ctr Excellence Comparat Planetol, Beijing, Peoples R China 2.Chinese Acad Sci, Purple Mt Observ, Key Lab Planetary Sci, Nanjing 210034, Jiangsu, Peoples R China 3.Maine Mineral & Gem Museum, 99 Main St,POB 500, Bethel, ME 04217 USA 4.Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA |
| 推荐引用方式 GB/T 7714 | Rubin, Alan E.,Li, Ye. Formation and destruction of magnetite in CO3 chondrites and other chondrite groups[J]. GEOCHEMISTRY,2019,79(4):10. |
| APA | Rubin, Alan E.,&Li, Ye.(2019).Formation and destruction of magnetite in CO3 chondrites and other chondrite groups.GEOCHEMISTRY,79(4),10. |
| MLA | Rubin, Alan E.,et al."Formation and destruction of magnetite in CO3 chondrites and other chondrite groups".GEOCHEMISTRY 79.4(2019):10. |
入库方式： OAI收割
来源：紫金山天文台
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