Iron isotope fractionation during magmatic-hydrothermal evolution: A case study from the Duolong porphyry Cu-Au deposit, Tibet
文献类型：期刊论文
| 作者 | Li, Jin-Xiang1,2; Qin, Ke-Zhang2,3; Li, Guang-Ming2,3; Evans, Noreen J.4; Huang, Fang5; Zhao, Jun-Xing3 |
| 刊名 | GEOCHIMICA ET COSMOCHIMICA ACTA
 |
| 出版日期 | 2018-10-01 |
| 卷号 | 238页码:1-15 |
| 关键词 | Fe isotope Magmatic-hydrothermal evolution Porphyry Cu-Au deposit Duolong Tibet |
| ISSN号 | 0016-7037 |
| DOI | 10.1016/j.gca.2018.07.008 |
| 英文摘要 | Ore-forming fluids ultimately precipitate Fe-bearing sulfides and oxides in hydrothermal ore deposits and the Fe isotopic composition of these minerals can trace magmatic-hydrothermal evolution. Here, we report on the Fe isotopic compositions of a suite of hydrothermal minerals (magnetite, pyrite, and chalcopyrite) and granodiorite porphyry from the giant Duolong porphyry Cu-Au deposit (Bolong and Duobuza section), central Tibet. Most magnetite grains with potassic alteration show only minor delta Fe-57 variation (0.38 +/- 0.07 parts per thousand to 0.52 +/- 0.04 parts per thousand in Bolong and 0.68 +/- 0.02 parts per thousand to 0.77 +/- 0.08 parts per thousand in Duobuza), consistent with the equilibrium fluid delta Fe-57 (similar to-0.3 parts per thousand and similar to-0.1 parts per thousand, respectively) at similar to 550-480 degrees C. The equilibrium fluids have lighter Fe isotope signatures than the Duolong granodiorite porphyry (delta Fe-57 = 0.03 +/- 0.06 parts per thousand to 0.07 +/- 0.02 parts per thousand), corroborating the hypothesis that exsolved fluids should have a lighter Fe isotopic composition relative to parental magmas. Chalcopyrite from the mineralized Bolong and Duobuza porphyries have relatively consistent delta Fe-57 values of -0.60 +/- 0.07 parts per thousand to -0.42 +/- 0.07 parts per thousand and -0.40 +/- 0.08 parts per thousand to -0.30 +/- 0.05 parts per thousand, respectively, with equilibrium fluids at similar to 450-350 degrees C having lighter delta Fe-57 values of similar to-0.7 parts per thousand and similar to-0.6 parts per thousand. The trend of decreasing delta Fe-57 values in evolved fluids likely reflects Rayleigh fractionation of magnetite enriched in heavy Fe isotopes. This supposition is supported by the lighter delta Fe-57 value (0.25 +/- 0.07 parts per thousand) recorded in magnetite that equilibrated with a lighter delta Fe-57 fluid (similar to-0.5 parts per thousand) at similar to 470 degrees C. Compared to chalcopyrite, pyrite from the Bolong and Duobuza sections have heavier delta Fe-57 values of 0.35 +/- 0.06 parts per thousand to 0.71 +/- 0.06 parts per thousand and 0.53 +/- 0.06 parts per thousand to 0.71 +/- 0.07 parts per thousand, respectively. The pyrite values correlate variably with the Fe isotopic composition of ore-forming fluids (delta Fe-57 -0.6 parts per thousand to -0.7 parts per thousand), likely due to variations in the degree of Fe isotope exchange between pyrite and fluid. Moreover, combined with previously published Fe isotopic compositions of hydrothermal minerals from oxidized and reduced ore deposits, the results show that chalcopyrite in oxidized hydrothermal deposits always has a lighter Fe isotopic composition than chalcopyrite from reduced hydrothermal deposits. This is likely controlled by melt composition and precipitation of magnetite/pyrrhotite-bearing mineral assemblages. Therefore, the Fe isotopic composition of chalcopyrite could be a useful diagnostic tool for distinguishing oxidized from reduced fluids in hydrothermal systems. (C) 2018 Elsevier Ltd. All rights reserved. |
| WOS关键词 | FE-ISOTOPE ; COPPER-DEPOSIT ; U-PB ; MOSSBAUER-SPECTROSCOPY ; QIANGTANG TERRANE ; AQUEOUS-SOLUTION ; HIGH-TEMPERATURE ; INTRUSIVE ROCKS ; SOUTHERN TIBET ; NORTHERN TIBET |
| 资助项目 | Natural Science Foundation[41672091] ; Natural Science Foundation[41490613] ; Ministry of Science and Technology of China[2016YFC0600303] |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000441893500001 |
| 出版者 | PERGAMON-ELSEVIER SCIENCE LTD |
| 资助机构 | Natural Science Foundation ; Natural Science Foundation ; Ministry of Science and Technology of China ; Ministry of Science and Technology of China ; Natural Science Foundation ; Natural Science Foundation ; Ministry of Science and Technology of China ; Ministry of Science and Technology of China ; Natural Science Foundation ; Natural Science Foundation ; Ministry of Science and Technology of China ; Ministry of Science and Technology of China ; Natural Science Foundation ; Natural Science Foundation ; Ministry of Science and Technology of China ; Ministry of Science and Technology of China |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/88117]  |
| 专题 | 地质与地球物理研究所_中国科学院矿产资源研究重点实验室 |
| 通讯作者 | Li, Jin-Xiang |
| 作者单位 | 1.Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Continental Collis & Plateau Uplift, Beijing 100101, Peoples R China 2.CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China 3.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China 4.Curtin Univ, John de Laeter Ctr, TIGeR, Appl Geol, Perth, WA 6945, Australia 5.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China |
| 推荐引用方式 GB/T 7714 | Li, Jin-Xiang,Qin, Ke-Zhang,Li, Guang-Ming,et al. Iron isotope fractionation during magmatic-hydrothermal evolution: A case study from the Duolong porphyry Cu-Au deposit, Tibet[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2018,238:1-15. |
| APA | Li, Jin-Xiang,Qin, Ke-Zhang,Li, Guang-Ming,Evans, Noreen J.,Huang, Fang,&Zhao, Jun-Xing.(2018).Iron isotope fractionation during magmatic-hydrothermal evolution: A case study from the Duolong porphyry Cu-Au deposit, Tibet.GEOCHIMICA ET COSMOCHIMICA ACTA,238,1-15. |
| MLA | Li, Jin-Xiang,et al."Iron isotope fractionation during magmatic-hydrothermal evolution: A case study from the Duolong porphyry Cu-Au deposit, Tibet".GEOCHIMICA ET COSMOCHIMICA ACTA 238(2018):1-15. |
入库方式： OAI收割
来源：地质与地球物理研究所
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