Fluid effect on zircon O and U-Pb isotopes during ultrahigh-pressure metamorphism: Insights from the Dora-Maira Massif of the Western
文献类型：期刊论文
| 作者 | Zhou, Kun2; Chen, Yi-Xiang2,3; Xiong, Jia-Wei2; Schertl, Hans-Peter4,5; Xia, Xiao-Ping1 |
| 刊名 | GEOSCIENCE FRONTIERS
 |
| 出版日期 | 2023-11-01 |
| 卷号 | 14期号:6页码:14 |
| 关键词 | Subduction zone Fluid action Metasomatism Zircon O isotope U-Pb dating |
| ISSN号 | 1674-9871 |
| DOI | 10.1016/j.gsf.2023.101651 |
| 英文摘要 | Zircon geochemistry such as U-Pb and O isotopes have been widely used in dating and tracing complex geological processes. However, it still remains unclear how fluid action affects zircon geochemistry during metamorphic and metasomatic processes in subduction zones. Here a systematic study on zircon U-Pb dating, O isotopes and trace elements as well as whole-rock O isotopes was carried out for the coesite-bearing whiteschists, jadeite quartzites and granitic gneisses from the Dora-Maira Massif, Western Alps. Whole-rock and zircon geochemistry supports a common protolith, i.e., Permian S-type granites, for the above three types of rocks and an intense fluid metasomatism during the Alpine orogeny to form whiteschists and jadeite quartzites. Zircon cores in all samples have nearly identical delta O-18 values (9 parts per thousand-11 parts per thousand), whereas their apparent Pb-206/U-238 ages show a greater variability due to Pb loss during metamorphism. Zircon rims formed in the late Eocene to early Oligocene can be categorized into two types. Type-I rims occur in granitic gneisses and jadeite quartzites. They have high delta O-18 values consistent with zircon cores, but much lower contents of P and Y as well as lower Th/U ratios than the cores. Their growth can be attributed to internal metamorphic fluid action at the UHP metamorphic stage. Type-II rims occur in whiteschists and jadeite quartzites. They have remarkably lower delta O-18 values (5 parts per thousand-8 parts per thousand) and Th/U ratios (<0.01), compared with zircon cores and Type-I rims. Their growth can be ascribed to external fluids during the metasomatic process. Some zircon domains in whiteschists and jadeite quartzites show a positive correlation between delta O-18 values and apparent Pb-206/U-238 ages, which suggest the simultaneous impacts on U-Pb-O isotopes during external fluid metasomatism. This process can be attributed to the fluidassisted dissolution and recrystallization of protolith zircons. Especially, coesite inclusions that would have been expected to occur only in young zircon rims formed during UHP metamorphism are also observed in the relict magmatic zircon cores, indicating that the fluid-related metasomatism at the UHP metamorphic conditions also affected these pre-existing protolith-related cores. Therefore, fluid action in subduction zones reveals significant impacts on both the U-Pb and O isotope systems of zircon, especially when external metasomatic fluids are involved. Therefore, a detailed study on zircon, including microstructure, mineral inclusion and geochemical data of different growth and recrystallization domains, is needed in order to unravel continental crustal evolution based on zircon U-Pb ages and O isotope compositions. (C) 2023 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:001062681600001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/74843]  |
| 专题 | 同位素地球化学国家重点实验室 |
| 通讯作者 | Chen, Yi-Xiang |
| 作者单位 | 1.Chinese Acad Sci, State Key Lab Isotope Geochem, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China 2.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 3.Univ Sci & Technol China, CAS Ctr Excellence Comparat Planetol, Hefei 230026, Peoples R China 4.Ruhr Univ Bochum, Inst Geol Mineral & Geophys, Fac Geosci, D-44780 Bochum, Germany 5.Shandong Univ Sci & Technol, Coll Earth Sci & Engn, Qingdao 266590, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zhou, Kun,Chen, Yi-Xiang,Xiong, Jia-Wei,et al. Fluid effect on zircon O and U-Pb isotopes during ultrahigh-pressure metamorphism: Insights from the Dora-Maira Massif of the Western[J]. GEOSCIENCE FRONTIERS,2023,14(6):14. |
| APA | Zhou, Kun,Chen, Yi-Xiang,Xiong, Jia-Wei,Schertl, Hans-Peter,&Xia, Xiao-Ping.(2023).Fluid effect on zircon O and U-Pb isotopes during ultrahigh-pressure metamorphism: Insights from the Dora-Maira Massif of the Western.GEOSCIENCE FRONTIERS,14(6),14. |
| MLA | Zhou, Kun,et al."Fluid effect on zircon O and U-Pb isotopes during ultrahigh-pressure metamorphism: Insights from the Dora-Maira Massif of the Western".GEOSCIENCE FRONTIERS 14.6(2023):14. |
入库方式： OAI收割
来源：广州地球化学研究所
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