下大洋地壳中锌同位素的大变化为研究大洋地壳岩浆管道系统提供了新的思路

IF 4.5 1区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS
Wei-Qi Zhang, Chuan-Zhou Liu, Zong-Qi Zou, Xiao-Ni Li
{"title":"下大洋地壳中锌同位素的大变化为研究大洋地壳岩浆管道系统提供了新的思路","authors":"Wei-Qi Zhang, Chuan-Zhou Liu, Zong-Qi Zou, Xiao-Ni Li","doi":"10.1016/j.gca.2025.05.005","DOIUrl":null,"url":null,"abstract":"Constraining mid-ocean ridge magmatic processes is crucial for understanding the geochemical evolution of magmas traversing the oceanic crust. A crucial archive for investigating these magmatic processes is the chemical composition of lower oceanic crust. This study presents Zn isotope data for primitive to highly evolved cumulates from the Mid-Atlantic Ridge (Kane) and the Southwest Indian Ridge (IODP Hole U1473A), which are compared with published mid-ocean ridge (MOR) lava data. Previous studies have indicated that high-degree magma differentiation results in small Zn isotope fractionation (&lt;0.1 ‰) in the mafic to felsic MOR lavas. Unlike the MOR lavas, significant δ<ce:sup loc=\"post\">66</ce:sup>Zn variations (0.1 − 0.5 ‰) are observed in the Kane and U1473A cumulates, which cannot be explained by crystal accumulation alone but reflect the variable incorporation of trapped melts. These trapped melts exhibit heavy δ<ce:sup loc=\"post\">66</ce:sup>Zn (&gt;0.5 ‰) and strongly fractionated trace element characteristics, indicative of extensive melt-rock interactions. Furthermore, the bulk normal mid-ocean ridge basalt (N-MORB)-type lower oceanic crust has δ<ce:sup loc=\"post\">66</ce:sup>Zn values (0.24 ± 0.11 ‰) that are close to the average N-MORB (0.26 ± 0.06 ‰), suggesting minor Zn isotope fractionation during the crustal processing of MOR lavas. It is proposed that the small δ<ce:sup loc=\"post\">66</ce:sup>Zn variations in MOR magmas result from the homogenization and dilution of reactive signals within the eruptive reservoir. In contrast, prolonged processing of trapped melts through melt-rock interactions leads to significant Zn isotope fractionation in the lower oceanic crust. Thus, the evolution of oceanic crustal magma plumbing systems is more complex than inferred from MORB alone. Despite these complexities, efficient homogenization within eruptive reservoirs results in limited Zn isotopic variations in the erupted magmas. Hence, the Zn isotopic variations in MORB, except for the highly evolved ones, are predominantly linked to the source heterogeneity. Our findings also suggest heterogeneous δ<ce:sup loc=\"post\">66</ce:sup>Zn in subducted oceanic crusts, which has implications for mantle Zn isotope heterogeneity.","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"77 1","pages":""},"PeriodicalIF":4.5000,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Large Zn isotope variations in lower oceanic crust offer insights into oceanic crustal magma plumbing system\",\"authors\":\"Wei-Qi Zhang, Chuan-Zhou Liu, Zong-Qi Zou, Xiao-Ni Li\",\"doi\":\"10.1016/j.gca.2025.05.005\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Constraining mid-ocean ridge magmatic processes is crucial for understanding the geochemical evolution of magmas traversing the oceanic crust. A crucial archive for investigating these magmatic processes is the chemical composition of lower oceanic crust. This study presents Zn isotope data for primitive to highly evolved cumulates from the Mid-Atlantic Ridge (Kane) and the Southwest Indian Ridge (IODP Hole U1473A), which are compared with published mid-ocean ridge (MOR) lava data. Previous studies have indicated that high-degree magma differentiation results in small Zn isotope fractionation (&lt;0.1 ‰) in the mafic to felsic MOR lavas. Unlike the MOR lavas, significant δ<ce:sup loc=\\\"post\\\">66</ce:sup>Zn variations (0.1 − 0.5 ‰) are observed in the Kane and U1473A cumulates, which cannot be explained by crystal accumulation alone but reflect the variable incorporation of trapped melts. These trapped melts exhibit heavy δ<ce:sup loc=\\\"post\\\">66</ce:sup>Zn (&gt;0.5 ‰) and strongly fractionated trace element characteristics, indicative of extensive melt-rock interactions. Furthermore, the bulk normal mid-ocean ridge basalt (N-MORB)-type lower oceanic crust has δ<ce:sup loc=\\\"post\\\">66</ce:sup>Zn values (0.24 ± 0.11 ‰) that are close to the average N-MORB (0.26 ± 0.06 ‰), suggesting minor Zn isotope fractionation during the crustal processing of MOR lavas. It is proposed that the small δ<ce:sup loc=\\\"post\\\">66</ce:sup>Zn variations in MOR magmas result from the homogenization and dilution of reactive signals within the eruptive reservoir. In contrast, prolonged processing of trapped melts through melt-rock interactions leads to significant Zn isotope fractionation in the lower oceanic crust. Thus, the evolution of oceanic crustal magma plumbing systems is more complex than inferred from MORB alone. Despite these complexities, efficient homogenization within eruptive reservoirs results in limited Zn isotopic variations in the erupted magmas. Hence, the Zn isotopic variations in MORB, except for the highly evolved ones, are predominantly linked to the source heterogeneity. Our findings also suggest heterogeneous δ<ce:sup loc=\\\"post\\\">66</ce:sup>Zn in subducted oceanic crusts, which has implications for mantle Zn isotope heterogeneity.\",\"PeriodicalId\":327,\"journal\":{\"name\":\"Geochimica et Cosmochimica Acta\",\"volume\":\"77 1\",\"pages\":\"\"},\"PeriodicalIF\":4.5000,\"publicationDate\":\"2025-05-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geochimica et Cosmochimica Acta\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1016/j.gca.2025.05.005\",\"RegionNum\":1,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochimica et Cosmochimica Acta","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1016/j.gca.2025.05.005","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0

摘要

约束洋中脊岩浆过程对于理解穿越洋壳的岩浆地球化学演化具有重要意义。研究这些岩浆过程的一个重要资料是海底地壳的化学成分。本文介绍了中大西洋脊(Kane)和西南印度洋脊(IODP孔U1473A)原始至高度演化的Zn同位素资料,并与已发表的中洋脊(MOR)熔岩资料进行了比较。前人研究表明,岩浆分异程度高,导致镁质-长英质MOR熔岩中Zn同位素分异较小(<0.1‰)。与MOR熔岩不同的是,Kane和U1473A熔岩的δ66Zn变化显著(0.1 ~ 0.5‰),这不能单独用晶体积累来解释,而是反映了被困熔体的变化。这些被困熔体表现出重δ66Zn (>0.5‰)和强烈的微量元素分馏特征,表明熔体-岩石相互作用广泛。此外,大块正常中洋脊玄武岩(N-MORB)型下洋壳的δ66Zn值(0.24±0.11‰)接近平均N-MORB值(0.26±0.06‰),表明在MOR熔岩地壳加工过程中,Zn同位素分选作用较小。认为MOR岩浆δ66Zn的小变化是由于喷发储层内反应信号的均匀化和稀释所致。相比之下,由于熔体-岩石相互作用,被困熔体的长时间加工导致了下洋壳中显著的Zn同位素分馏。因此,海洋地壳岩浆管道系统的演化比仅从MORB推断更为复杂。尽管存在这些复杂性,但喷发储层内部的有效均质化导致喷发岩浆中锌同位素的变化有限。因此,除了高度演化的Zn同位素外,MORB中Zn同位素的变化主要与源的非均质性有关。研究结果还表明,俯冲洋壳中δ66Zn的非均质性可能与地幔Zn同位素的非均质性有关。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Large Zn isotope variations in lower oceanic crust offer insights into oceanic crustal magma plumbing system
Constraining mid-ocean ridge magmatic processes is crucial for understanding the geochemical evolution of magmas traversing the oceanic crust. A crucial archive for investigating these magmatic processes is the chemical composition of lower oceanic crust. This study presents Zn isotope data for primitive to highly evolved cumulates from the Mid-Atlantic Ridge (Kane) and the Southwest Indian Ridge (IODP Hole U1473A), which are compared with published mid-ocean ridge (MOR) lava data. Previous studies have indicated that high-degree magma differentiation results in small Zn isotope fractionation (<0.1 ‰) in the mafic to felsic MOR lavas. Unlike the MOR lavas, significant δ66Zn variations (0.1 − 0.5 ‰) are observed in the Kane and U1473A cumulates, which cannot be explained by crystal accumulation alone but reflect the variable incorporation of trapped melts. These trapped melts exhibit heavy δ66Zn (>0.5 ‰) and strongly fractionated trace element characteristics, indicative of extensive melt-rock interactions. Furthermore, the bulk normal mid-ocean ridge basalt (N-MORB)-type lower oceanic crust has δ66Zn values (0.24 ± 0.11 ‰) that are close to the average N-MORB (0.26 ± 0.06 ‰), suggesting minor Zn isotope fractionation during the crustal processing of MOR lavas. It is proposed that the small δ66Zn variations in MOR magmas result from the homogenization and dilution of reactive signals within the eruptive reservoir. In contrast, prolonged processing of trapped melts through melt-rock interactions leads to significant Zn isotope fractionation in the lower oceanic crust. Thus, the evolution of oceanic crustal magma plumbing systems is more complex than inferred from MORB alone. Despite these complexities, efficient homogenization within eruptive reservoirs results in limited Zn isotopic variations in the erupted magmas. Hence, the Zn isotopic variations in MORB, except for the highly evolved ones, are predominantly linked to the source heterogeneity. Our findings also suggest heterogeneous δ66Zn in subducted oceanic crusts, which has implications for mantle Zn isotope heterogeneity.
求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
Geochimica et Cosmochimica Acta
Geochimica et Cosmochimica Acta 地学-地球化学与地球物理
CiteScore
9.60
自引率
14.00%
发文量
437
审稿时长
6 months
期刊介绍: Geochimica et Cosmochimica Acta publishes research papers in a wide range of subjects in terrestrial geochemistry, meteoritics, and planetary geochemistry. The scope of the journal includes: 1). Physical chemistry of gases, aqueous solutions, glasses, and crystalline solids 2). Igneous and metamorphic petrology 3). Chemical processes in the atmosphere, hydrosphere, biosphere, and lithosphere of the Earth 4). Organic geochemistry 5). Isotope geochemistry 6). Meteoritics and meteorite impacts 7). Lunar science; and 8). Planetary geochemistry.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信