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Rubidium isotopes reveal dehydration and melting of the subducting slab beneath the Mariana arc

文献类型：期刊论文

作者Jiang, Ding-Sheng5,6; Peng, Xiao-Tong4; Xu, Wen-Jing4; Hu, Xia5,6; Erdmann, Saskia; Xu, Xi-Sheng3; Zhang, Guo-Liang2; Pang, Chong-Jin1; Duan, Hao-Chen5,6; Huang, Fang5,6
刊名EARTH AND PLANETARY SCIENCE LETTERS
出版日期2024-11-15
卷号646页码:13
关键词Rb isotopes Subduction zones Mariana arc AOC dehydration Sediment partial melting
ISSN号0012-821X
DOI10.1016/j.epsl.2024.118978
英文摘要Rubidium (Rb) is a strongly incompatible and highly fluid-mobile element and Rb isotopes have the potential to track subducted material recycling to the mantle source of arc magmas. However, the behavior of Rb isotopes during slab subduction and associated processes remains unconstrained. This study for the first time presents Rb isotope data for the altered oceanic crust (AOC) from IODP Site U1365, subducted sediments, and lavas from the Southern Mariana arc. The delta Rb-87 of the AOC varies between -0.16 +/- 0.03 parts per thousand to 0.07 +/- 0.02 parts per thousand with a weighted average of -0.02 +/- 0.06 parts per thousand, which is higher than that of fresh mid-ocean ridge basalts (MORB; -0.12 +/- 0.08 parts per thousand). Such Rb isotope fractionation may be attributed to the preferential loss of Rb-85 into seawater during the dissolution of primary phases and the preferential structural incorporation of Rb-87 into secondary phases and preferential Rb-87 adsorption by clays. The delta Rb-87 of the sediments varies from -0.20 +/- 0.07 parts per thousand to -0.03 +/- 0.02 parts per thousand with an average of -0.11 +/- 0.12 parts per thousand, identical to that of the upper continental crust (UCC; -0.14 +/- 0.08 parts per thousand). The correlations observed between delta Rb-87 and sediment depth (and loss on ignition; LOI) suggest that hydrodynamic sorting of sediments which enriches the upper stratigraphic intervals in clays, exerts a first-order control on the Rb isotope fractionation in subducted sediments. The formation of authigenic clays, which act as a sink of Rb-85 from seawater, could partially account for the elevated delta Rb-87 of seawater (0.14 +/- 0.12 parts per thousand) relative to the Bulk Silicate Earth (BSE; -0.12 +/- 0.06 parts per thousand). For the Mariana lavas, the delta Rb-87 decreases from fore-arc lavas (-0.03 +/- 0.04 parts per thousand to 0.09 +/- 0.02 parts per thousand) to frontal arc lavas (-0.12 +/- 0.04 parts per thousand to -0.01 +/- 0.03 parts per thousand), which are all higher than the average delta Rb-87 of fresh MORB (-0.12 +/- 0.08 parts per thousand). The elevated delta Rb-87 of the lavas reflects the addition of AOC-derived aqueous fluids with a high delta Rb-87 (similar to 0.08 parts per thousand) to the magma source, which is higher than the average delta Rb-87 (-0.02 +/- 0.18 parts per thousand) of the Site-1365 AOC. The variation of delta Rb-87 with Nd-143/Nd-144(i) values of the lavas indicates that AOC-derived aqueous fluids are increasingly mixed with a component with a low delta Rb-87 that most likely represents sediment melts. The estimated delta Rb-87 of sediment melts is about -0.27 parts per thousand, lower than the average delta Rb-87 (-0.11 +/- 0.12 parts per thousand) of the Mariana sediments. Thus, our study suggests that Rb isotopes can be fractionated during AOC dehydration and sediment partial melting. Overall, the across-arc Rb isotope variation reflects slab dehydration and melting at different subduction depths. Our findings demonstrate that Rb isotopes are a powerful novel tool for probing deep recycling of subducted slabs. Furthermore, they can distinguish contributions from AOC-derived fluids versus sediment-derived melts to the source of arc magmas.
WOS关键词ALTERED OCEANIC-CRUST ; TRACE-ELEMENT ; EXPERIMENTAL CONSTRAINTS ; FRACTIONATION ; ORIGIN ; FLUIDS ; GEOCHEMISTRY ; SYSTEMATICS ; POTASSIUM ; ECLOGITES
资助项目National Natural Science Foun-dation of China[4233000014] ; National Key Research and Development Program of China[2022YFF0800402]
WOS研究方向Geochemistry & Geophysics
语种英语
WOS记录号WOS:001318055500001
出版者ELSEVIER
资助机构National Natural Science Foun-dation of China ; National Key Research and Development Program of China
源URL[http://ir.idsse.ac.cn/handle/183446/11368]  
专题专家咨询委员会
深海科学研究部_深海地质与地球化学研究室
通讯作者Huang, Fang
作者单位1.Guilin Univ Technol, Guangxi Key Lab Hidden Met Ore Deposits Explorat, Guilin 541004, Peoples R China
2.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China
3.Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Peoples R China
4.Chinese Acad Sci, Inst Deep Sea Sci & Engn, Sanya 572000, Peoples R China
5.Univ Sci & Technol China, CAS Ctr Excellence Comparat Planetol, Hefei 230026, Peoples R China
6.Univ Sci & Technol China, State Key Lab Lithospher & Environm Coevolut, Hefei 230026, Peoples R China
推荐引用方式
GB/T 7714		 Jiang, Ding-Sheng,Peng, Xiao-Tong,Xu, Wen-Jing,et al. Rubidium isotopes reveal dehydration and melting of the subducting slab beneath the Mariana arc[J]. EARTH AND PLANETARY SCIENCE LETTERS,2024,646:13.
APA Jiang, Ding-Sheng.,Peng, Xiao-Tong.,Xu, Wen-Jing.,Hu, Xia.,Erdmann, Saskia.,...&Huang, Fang.(2024).Rubidium isotopes reveal dehydration and melting of the subducting slab beneath the Mariana arc.EARTH AND PLANETARY SCIENCE LETTERS,646,13.
MLA Jiang, Ding-Sheng,et al."Rubidium isotopes reveal dehydration and melting of the subducting slab beneath the Mariana arc".EARTH AND PLANETARY SCIENCE LETTERS 646(2024):13.

入库方式： OAI收割

来源：深海科学与工程研究所

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