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| Iron isotopic composition of supra-subduction zone ophiolitic peridotite from northern Tibet | |
Zhang, Long1; Sun, Wei-dong2,3,4 ; Zhang, Zhaofeng5; An, Yajun5; Liu, Fang5
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| 2019-08-01 | |
| Source Publication | GEOCHIMICA ET COSMOCHIMICA ACTA
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| ISSN | 0016-7037 |
| Volume | 258Pages:274-289 |
| Corresponding Author | Zhang, Long(zhanglong@gig.ac.cn) ; Sun, Wei-dong(weidongsun@qdio.ac.cn) |
| Abstract | We present high-precision iron isotope data for harzburgites and constituting minerals from the Yushigou suprasubduction zone ophiolite in the North Qilian orogen of northern Tibet to provide insights into iron isotope behavior in subduction zones. The Yushigou harzburgites represent typical melting residues of silica-enriched forearc mantle wedge with significant melt extraction and minimal melt percolation. The delta Fe-56 ranges from -0.096% to 0.110% in olivine, from -0.111% to 0.105% in orthopyroxene and from -0.141% to 0.054% in spinel. Coexisting minerals fall on a line with a slope of 1 in the delta-delta plot, indicating iron isotope equilibrium between mineral pairs. Iron isotopic fractionation between olivine and orthopyroxene is minor, which is consistent with theoretical predictions and previous observations. Good iron isotopic equilibrium between olivine and orthopyroxene is a further indicator that silica enrichment in arc peridotites is inherited from their mantle source. In contrast, significantly negative iron isotopic fractionation between spinel and olivine contradicts with most previous constraints, which may be ascribed to Cr substitution in spinel. Bulk rock harzburgites have delta Fe-56 ranging from -0.097% to 0.076%, the average of which (0.002 +/- 0.020%) is similar to average delta Fe-56 determined for abyssal peridotites. Based on this inference, the lower delta Fe-56 of arc magmas than MORB should be due to smaller discrepancy in Fe3+/RFe between arc magmas and arc peridotites when compared with MORB and abyssal peridotites. Our modelling demonstrates that this can be achieved if arc magmas are produced by redox-buffered melting of silica-enriched mantle wedge while MORB are produced by redox-unbuffered melting of the depleted mantle. (C) 2019 Elsevier Ltd. All rights reserved. |
| Keyword | Iron isotopes Mantle wedge Peridotite Subduction zone North Qilian |
| DOI | 10.1016/j.gca.2019.04.031 |
| Indexed By | SCI |
| Language | 英语 |
| Funding Project | Strategic Priority Research Program of the Chinese Academy of Sciences[XDB18000000] ; National Key R&D Program of China[2016YFC0600408] ; China Postdoctoral Science Foundation[2016LH00023] |
| WOS Research Area | Geochemistry & Geophysics |
| WOS Subject | Geochemistry & Geophysics |
| WOS ID | WOS:000472708700017 |
| Publisher | PERGAMON-ELSEVIER SCIENCE LTD |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.qdio.ac.cn/handle/337002/161841 |
| Collection | 深海极端环境与生命过程研究中心 |
| Corresponding Author | Zhang, Long; Sun, Wei-dong |
| Affiliation | 1.Chinese Acad Sci, Guangzhou Inst Geochem, CAS Key Lab Mineral & Metallogeny, Guangzhou 510640, Guangdong, Peoples R China 2.Chinese Acad Sci, Ctr Deep Sea Res, Inst Oceanol, Qingdao 266071, Shandong, Peoples R China 3.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266237, Shandong, Peoples R China 4.Chinese Acad Sci, CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China 5.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China |
| Corresponding Author Affilication | Institute of Oceanology, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | Zhang, Long,Sun, Wei-dong,Zhang, Zhaofeng,et al. Iron isotopic composition of supra-subduction zone ophiolitic peridotite from northern Tibet[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2019,258:274-289. |
| APA | Zhang, Long,Sun, Wei-dong,Zhang, Zhaofeng,An, Yajun,&Liu, Fang.(2019).Iron isotopic composition of supra-subduction zone ophiolitic peridotite from northern Tibet.GEOCHIMICA ET COSMOCHIMICA ACTA,258,274-289. |
| MLA | Zhang, Long,et al."Iron isotopic composition of supra-subduction zone ophiolitic peridotite from northern Tibet".GEOCHIMICA ET COSMOCHIMICA ACTA 258(2019):274-289. |
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