Serpentinite geochemistry documents the earliest dehydration and decarbonation of the subducting slab beneath the Mariana forearc
文献类型：期刊论文
| 作者 | Zhao, Rui-Peng3,4; Li, Hong-Yan3; Ryan, Jeffrey G.1; Johnston, Raymond M.1; Jensen, Owen2; Xu, Yi-Gang3,4 |
| 刊名 | EARTH AND PLANETARY SCIENCE LETTERS
 |
| 出版日期 | 2024-07-01 |
| 卷号 | 637页码:13 |
| 关键词 | Earliest slab dehydration Decarbonation Forearc serpentinites Blueschist-facies metamorphism Seamount subduction |
| ISSN号 | 0012-821X |
| DOI | 10.1016/j.epsl.2024.118748 |
| 英文摘要 | The geochemistry of Mariana forearc serpentinites sheds light on how the subducting slab starts to devolatilize. International Ocean Discovery Program Expedition 366 targeted three serpentinite seamounts: Yinazao, Fantangisn a and As & ugrave;t Tesoru, with corresponding slab depths of 13, 14 and 18 km, respectively. The fluid-mobile elements (FMEs) B, Rb, Cs, and Li become more enriched in the eruptive serpentinites with increasing slab depth. Yinazao serpentinites show strongly elevated Sr and Ba contents, which complements depletions in these elements seen in mafic clasts entrained in the serpentinites. Correlations between the FMEs and 87 Sr/ 86 Sr of the serpentinites reflect interactions among slab fluid, mantle and the subducting slab. With the enrichments of Sr-Ba in the Yinazao and B-Rb-Cs-Li in the As & ugrave;t Tesoru serpentinites, their 87 Sr/ 86 Sr converge toward values similar as those of the mafic clasts from values between sediments and the mantle. These observations indicate that sediment is the source of the earliest slab-derived fluids, which experienced extensive interaction first with mantle wedge peridotites to produce high pH fluids, and later with subducted seamount basalts. The decomposition of plagioclase in subducting basalts leads to precipitation of CaCO 3 from the high pH serpentinizing fluids and elevated Ca-Sr-Ba contents under low carbonate alkalinity conditions, as seen in the Yinazao serpentinites. The breakdown of clay minerals after lawsonite formation and the lizardite-antigorite transition release geochemically distinct fluids, with high B-Rb-Cs-Li and low Sr. This episode of fluid release results in the dissolution of CaCO 3 precipitated in the shallow subduction channel, and the generation of rodingite assemblages and epidote. Finally, these fluids evolve to have high carbonate alkalinity and low Ca-Sr-Ba contents, as seen in As & ugrave;t Tesoru serpentinites as well as those in South Chamorro and Conical Seamounts. This study reveals early plagioclase breakdown via high pH fluids in the subduction channel is important both for the generation of hydrous minerals and the precipitation of CaCO 3 in the subducting slab, subduction channel, and shallow mantle wedge. |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001242326700001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/78504]  |
| 专题 | 同位素地球化学国家重点实验室 |
| 通讯作者 | Li, Hong-Yan |
| 作者单位 | 1.Univ S Florida, Sch Geosci, Tampa, FL 33620 USA 2.Univ South Carolina, Sch Earth Ocean & Environm, Dept Geol, Columbia, SC 29208 USA 3.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Peoples R China 4.Southern Marine Sci & Engn Guangdong Lab Guangzhou, Guangzhou 511458, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zhao, Rui-Peng,Li, Hong-Yan,Ryan, Jeffrey G.,et al. Serpentinite geochemistry documents the earliest dehydration and decarbonation of the subducting slab beneath the Mariana forearc[J]. EARTH AND PLANETARY SCIENCE LETTERS,2024,637:13. |
| APA | Zhao, Rui-Peng,Li, Hong-Yan,Ryan, Jeffrey G.,Johnston, Raymond M.,Jensen, Owen,&Xu, Yi-Gang.(2024).Serpentinite geochemistry documents the earliest dehydration and decarbonation of the subducting slab beneath the Mariana forearc.EARTH AND PLANETARY SCIENCE LETTERS,637,13. |
| MLA | Zhao, Rui-Peng,et al."Serpentinite geochemistry documents the earliest dehydration and decarbonation of the subducting slab beneath the Mariana forearc".EARTH AND PLANETARY SCIENCE LETTERS 637(2024):13. |
入库方式： OAI收割
来源：广州地球化学研究所
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