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

doi:10.1016/j.epsl.2022.117423

	Large iron isotope fractionation during mantle wedge serpentinization: Implications for iron isotopes of arc magmas
	Deng, Jianghong 1,2,3; He, Yongsheng 4; Zartman, Robert E.1; Yang, Xiaoyong 3; Sun, Weidong1,2,5
	2022-04-01
发表期刊	EARTH AND PLANETARY SCIENCE LETTERS
ISSN	0012-821X
卷号	583 页码:9
通讯作者	Deng, Jianghong(jhdeng0507@163.com) ; He, Yongsheng(heys@cugb.edu.cn) ; Sun, Weidong(weidongsun@qdio.ac.cn)
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.
关键词	serpentinization iron isotope Mariana forearc mantle wedge mantle oxidation
DOI	10.1016/j.epsl.2022.117423
收录类别	SCI
语种	英语
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
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000784333900007
出版者	ELSEVIER
引用统计	被引频次：12[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/178886
专题	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.Chinese Acad Sci, Inst Oceanol, Ctr Deep Sea Res, Ctr Ocean Mega Sci, Qingdao 266071, Peoples R China 2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China 3.Univ Sci & Technol China, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Anhui, Peoples R China 4.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China 5.Univ Chinese Acad Sci, Sch Ocean Sci, Beijing 100049, Peoples R China
第一作者单位	深海极端环境与生命过程研究中心
通讯作者单位	深海极端环境与生命过程研究中心
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.

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