Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas

doi:10.1016/j.epsl.2022.117423

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	Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas
	Deng, Jianghong 2,4,5; He, Yongsheng 1; Zartman, Robert E.4; Yang, Xiaoyong 2; Sun, Weidong 3,4,5
刊名	EARTH AND PLANETARY SCIENCE LETTERS
	2022-04-01
卷号	583 页码:9
关键词	serpentinization iron isotope Mariana forearc mantle wedge mantle oxidation
ISSN号	0012-821X
DOI	10.1016/j.epsl.2022.117423
通讯作者	Deng, Jianghong(jhdeng0507@163.com) ; He, Yongsheng(heys@cugb.edu.cn) ; Sun, Weidong(weidongsun@qdio.ac.cn)
英文摘要	Arc magmas are usually more oxidized than lavas from intraplate settings and spreading ridges. However, iron isotopes of arc magmas are generally lighter, and the mechanism is still controversial. The mantle wedge serpentinite provides new insights to resolve this issue. Here we show that mantle wedge serpentinites/serpentinized peridotites from the Mariana forearc mantle wedge have both heavy Fe isotopes (delta Fe-56 = -0.01-0.15%o) and high Fe3+/sigma Fe values (0.50-0.88), which are positively correlated. This indicates coupled iron oxidation and iron isotope fractionation induced by serpentinization in the mantle wedge. The high Fe3+/sigma Fe values and high SO3 contents of the mature serpentinites further suggest that the forearc mantle wedge is highly oxidized. Here we present a new mechanism for iron isotope fractionation and iron oxidation during mantle wedge serpentinization. Because iron solubility is low in the resultant high-pH fluids at the early stage of serpentinization, ferrous iron liberated during olivine serpentinization preferentially precipitates as serpentine, Fe-rich brucite, and magnetite in the serpentinite. After the full consumption of olivine during the late-stage serpentinization, ferrous iron becomes soluble and mobile in low-pH chlorine/sulfate-rich penetrating fluids, and is therefore released to the fluid with light Fe isotopes during progressive serpentinization, leaving the residual serpentinite with heavy iron isotopes. This suggests that mature serpentinites at the base of mantle wedge can act as a filter that sequesters ferric iron with heavy iron isotopes and liberates ferrous iron with light iron isotopes to the penetrating slab fluid, which migrate up to the above mantle wedge and even the mantle melting zone. The highly oxidized forearc mantle wedge serpentinites can also be dragged down to the subarc depth, releasing oxidizing fluids by dehydration. These processes may oxidize the arc mantle wedge coupled with light Fe isotopes, the fluxed partial melting of which consequently produces oxidized arc magmas with light Fe isotopes. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
资助项目	Strategic Priority Research Program of the Chinese Academy of Sciences[XDA22050103] ; Strategic Priority Research Program of the Chinese Academy of Sciences[XDB42020303] ; Strategic Priority Research Program of the Chinese Academy of Sciences[XDB18020102] ; National Nat-ural Science Foundation of China[41803002] ; National Key R&D Program of China[2019YFA0708400] ; China Postdoc-toral Science Foundation[2018M642708] ; Qingdao National Laboratory for Marine Science and Technology[2017ASKJ02] ; Taishan Scholar Program of Shandong[ts201712075]
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	ELSEVIER
WOS记录号	WOS:000784333900007
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/178885]
专题	海洋研究所_深海极端环境与生命过程研究中心
通讯作者	Deng, Jianghong; He, Yongsheng; Sun, Weidong
作者单位	1.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China 2.Univ Sci & Technol China, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Anhui, Peoples R China 3.Univ Chinese Acad Sci, Sch Ocean Sci, Beijing 100049, Peoples R China 4.Chinese Acad Sci, Inst Oceanol, Ctr Deep Sea Res, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China 5.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China
推荐引用方式 GB/T 7714	Deng, Jianghong,He, Yongsheng,Zartman, Robert E.,et al. Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas[J]. EARTH AND PLANETARY SCIENCE LETTERS,2022,583:9.
APA	Deng, Jianghong,He, Yongsheng,Zartman, Robert E.,Yang, Xiaoyong,&Sun, Weidong.(2022).Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas.EARTH AND PLANETARY SCIENCE LETTERS,583,9.
MLA	Deng, Jianghong,et al."Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas".EARTH AND PLANETARY SCIENCE LETTERS 583(2022):9.