Multiple fluid-rock interactions in the subduction channel evidenced by magnesium isotopes
文献类型：期刊论文
| 作者 | Yao, Yongxiang2,3,5; Xiao, Yuanyuan2,3; Niu, Yaoling4; Sun, Weidong1,3,4 |
| 刊名 | GEOCHIMICA ET COSMOCHIMICA ACTA
 |
| 出版日期 | 2025-08-15 |
| 卷号 | 403页码:67-78 |
| 关键词 | Mg isotope Ocean crust subduction Fluids Carbonate Eclogite |
| ISSN号 | 0016-7037 |
| DOI | 10.1016/j.gca.2025.07.003 |
| 通讯作者 | Xiao, Yuanyuan(yuanyuan.xiao@qdio.ac.cn) |
| 英文摘要 | Fluids from the subducted oceanic slab are closely associated with mass transfer in subduction zones, which significantly affect the composition of arc magmas and deep mantle. Previous studies have shown that magnesium isotopes can be used to identify the source of fluids and to trace carbonate cycling. However, the Mg isotope variation as a function of fluids in the subduction channel remains obscure. As large-scale fluid flows and strong fluid-rock interactions can significantly enhance elemental mobility, Mg isotope variations may be recorded in metabasaltic rocks with large-scale veins (which represent original fluid pathways). Here we present Mg isotope data for different parts of a metabasaltic block from Tianshan (ultra)high pressure metamorphic belt, southwest of China to reveal the Mg isotope composition of fluids and their effects in the subduction channel. All the samples have been divided into three groups depending on their position in each "pillow" of the metamorphic block, i.e., those from the omphacite-rich interior, glaucophane-rich vein and transitional part. The omphacite-rich interior is mainly composed of omphacite and phengite, with minor garnet, while the glaucophane-rich vein mainly consists of garnet, glaucophane and epidote. The transitional part between the omphacite-rich interior and glaucophane-rich vein is dominated by epidote and carbonate, and aragonite has been widely replaced by dolomite. Together with our previous study, we think that the metabasaltic block has experienced two stages of rehydration overprinting after eclogitization: the first stage rehydration led to the common enrichment of LILEs in the whole block compared to its protolith E-MORB; the second stage rehydration resulted in the carbonate reprecipitation at the transitional part and the redistribution of garnet component. The delta Mg-26 values of the omphacite-rich interior are lower (-0.42 parts per thousand to -0.34 parts per thousand) than those of MORBs (-0.25 +/- 0.06 parts per thousand), which probably indicates that subduction dehydration can lead to lighter Mg isotope composition of the residual eclogite and heavier Mg isotope composition of the released fluids. Furthermore, the lighter Mg isotope composition of the transitional part (delta Mg-26 = -0.67 parts per thousand similar to -0.63 parts per thousand) and glaucophane-rich vein (delta Mg-26 = -0.71 parts per thousand similar to -0.54 parts per thousand) may be caused by the reprecipitation of dolomite and garnet through Ca-Mg exchange as the result of interaction with externally derived carbonate rich fluids. The residual fluid after the reprecipitation of carbonate minerals is also expected to show a heavier Mg isotope composition. In addition, the recrystallization of dolomite in the subduction channel could not only hamper the influence of subducted carbonate-derived fluids on the heavier Mg isotope composition of arc magmas compared to MORBs, but also facilitate the transfer of carbonate with lighter Mg isotope compositions into the deep mantle. |
| WOS关键词 | TRACE-ELEMENT MOBILIZATION ; WESTERN TIANSHAN ; TECTONIC IMPLICATIONS ; NW-CHINA ; O ISOTOPES ; MG ; ECLOGITE ; FRACTIONATION ; BLUESCHIST ; MANTLE |
| 资助项目 | National Natural Science Foundation of China[92479112] ; Science and Technology Innovation Project of Laoshan Laboratory[LSKJ202204104] ; Taishan Scholars Program[tsqn202211254] |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001535158500001 |
| 出版者 | PERGAMON-ELSEVIER SCIENCE LTD |
| 源URL | [http://ir.qdio.ac.cn/handle/337002/202668]  |
| 专题 | 海洋研究所_海洋环流与波动重点实验室 |
| 通讯作者 | Xiao, Yuanyuan |
| 作者单位 | 1.Chinese Acad Sci, Inst Oceanol, Ctr Deep Sea Res, Qingdao 266071, Peoples R China 2.Qingdao Marine Sci & Technol Ctr, Lab Marine Geol, Qingdao 266237, Peoples R China 3.Chinese Acad Sci, Inst Oceanol, Key Lab Ocean Observat & Forecasting, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China 4.Laoshan Lab, Qingdao 266237, Peoples R China 5.Univ Chinese Acad Sci, Beijing 100049, Peoples R China |
| 推荐引用方式 GB/T 7714 | Yao, Yongxiang,Xiao, Yuanyuan,Niu, Yaoling,et al. Multiple fluid-rock interactions in the subduction channel evidenced by magnesium isotopes[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2025,403:67-78. |
| APA | Yao, Yongxiang,Xiao, Yuanyuan,Niu, Yaoling,&Sun, Weidong.(2025).Multiple fluid-rock interactions in the subduction channel evidenced by magnesium isotopes.GEOCHIMICA ET COSMOCHIMICA ACTA,403,67-78. |
| MLA | Yao, Yongxiang,et al."Multiple fluid-rock interactions in the subduction channel evidenced by magnesium isotopes".GEOCHIMICA ET COSMOCHIMICA ACTA 403(2025):67-78. |
入库方式： OAI收割
来源：海洋研究所
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