弧基础和俯冲起始:对伊豆-波宁前弧下地壳/上地幔在俯冲起始过程中岩浆演化的见解

IF 3.5 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS
Matthew P Loocke, Jonathan E Snow
{"title":"弧基础和俯冲起始:对伊豆-波宁前弧下地壳/上地幔在俯冲起始过程中岩浆演化的见解","authors":"Matthew P Loocke, Jonathan E Snow","doi":"10.1093/petrology/egae038","DOIUrl":null,"url":null,"abstract":"Our understanding of the processes at work in the lower crust/upper mantle transition zone during subduction initiation and early arc development has suffered from a general lack of in situ samples. Here, we present the results of petrographic and geochemical analysis of 34 samples (9 harzburgites, 13 dunites, 2 orthopyroxenites, 3 olivine-gabbros, and 7 wehrlites) collected from the inner trench wall of the Bonin Ridge, Izu-Bonin forearc. The sample suite records three main melt-rock reaction events involving melts with forearc basalt (FAB)-like, boninitic, and transitional compositions. The wehrlitic and gabbroic rocks trend towards more transitional to FAB compositions and the rest towards more boninitic compositions. The crosscutting occurrence of all three events in a single sample (wehrlite D31-106) establishes a relative timing of the events like that reported for the volcanic edifice of the Bonin Ridge, which transitioned from forearc basalt volcanism at subduction initiation (c.a., 51-52 Ma) to boninitic volcanism (c.a., 50-51 Ma) as the subduction system matured. We therefore suggest that the lower crust/upper mantle transition of the Bonin Ridge preserves a record of the transition from FAB melts created by decompression melting at subduction initiation to arc-type flux melting and boninitic volcanism thereafter. Orthopyroxenites and two anomalously fresh harzburgites from the sample suite are suggested to represent the later boninitic melts and possibly the result of hybridization between such melts and residual peridotites, respectively. Diffuse melt-rock reaction between the later boninites and/or subduction-related fluids and the earlier-formed FAB-related crust is recorded by enrichments in fluid mobile elements and depletions in first row transition metals in clinopyroxenes from a metasomatic vein in wehrlite sample D31-106. The chemistry of the wehrlitic and gabbroic clinopyroxenes suggests that they crystallized from hydrous, highly-depleted melts which lack a slab fluid signature. We thus suggest that highly-depleted melt fractions might be created early on during subduction initiation by the introduction of seawater into the proto-mantle wedge. The overall FAB-like nature of the crustal wehrlites and gabbros would suggest that most of the lower arc crust was created by forearc extension during/following subduction initiation and that later, mature arc volcanism may have contributed little or no material to the lower crust/upper mantle record in the outer forearc.","PeriodicalId":16751,"journal":{"name":"Journal of Petrology","volume":"53 1","pages":""},"PeriodicalIF":3.5000,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Arc foundations and subduction initiation: Insights into the magmatic evolution of the lower crust/upper mantle of the Izu-Bonin forearc during subduction initiation\",\"authors\":\"Matthew P Loocke, Jonathan E Snow\",\"doi\":\"10.1093/petrology/egae038\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Our understanding of the processes at work in the lower crust/upper mantle transition zone during subduction initiation and early arc development has suffered from a general lack of in situ samples. Here, we present the results of petrographic and geochemical analysis of 34 samples (9 harzburgites, 13 dunites, 2 orthopyroxenites, 3 olivine-gabbros, and 7 wehrlites) collected from the inner trench wall of the Bonin Ridge, Izu-Bonin forearc. The sample suite records three main melt-rock reaction events involving melts with forearc basalt (FAB)-like, boninitic, and transitional compositions. The wehrlitic and gabbroic rocks trend towards more transitional to FAB compositions and the rest towards more boninitic compositions. The crosscutting occurrence of all three events in a single sample (wehrlite D31-106) establishes a relative timing of the events like that reported for the volcanic edifice of the Bonin Ridge, which transitioned from forearc basalt volcanism at subduction initiation (c.a., 51-52 Ma) to boninitic volcanism (c.a., 50-51 Ma) as the subduction system matured. We therefore suggest that the lower crust/upper mantle transition of the Bonin Ridge preserves a record of the transition from FAB melts created by decompression melting at subduction initiation to arc-type flux melting and boninitic volcanism thereafter. Orthopyroxenites and two anomalously fresh harzburgites from the sample suite are suggested to represent the later boninitic melts and possibly the result of hybridization between such melts and residual peridotites, respectively. Diffuse melt-rock reaction between the later boninites and/or subduction-related fluids and the earlier-formed FAB-related crust is recorded by enrichments in fluid mobile elements and depletions in first row transition metals in clinopyroxenes from a metasomatic vein in wehrlite sample D31-106. The chemistry of the wehrlitic and gabbroic clinopyroxenes suggests that they crystallized from hydrous, highly-depleted melts which lack a slab fluid signature. We thus suggest that highly-depleted melt fractions might be created early on during subduction initiation by the introduction of seawater into the proto-mantle wedge. The overall FAB-like nature of the crustal wehrlites and gabbros would suggest that most of the lower arc crust was created by forearc extension during/following subduction initiation and that later, mature arc volcanism may have contributed little or no material to the lower crust/upper mantle record in the outer forearc.\",\"PeriodicalId\":16751,\"journal\":{\"name\":\"Journal of Petrology\",\"volume\":\"53 1\",\"pages\":\"\"},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2024-04-04\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Petrology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://doi.org/10.1093/petrology/egae038\",\"RegionNum\":2,\"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":"Journal of Petrology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1093/petrology/egae038","RegionNum":2,"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

由于普遍缺乏原位样本,我们对俯冲起始和早期弧发育期间下地壳/上地幔过渡带工作过程的理解受到了影响。在此,我们展示了从伊豆-波宁前弧波宁海脊内侧海沟壁采集的 34 个样品(9 个哈兹堡岩、13 个白云岩、2 个正长辉石、3 个橄榄石-辉长岩和 7 个魏长岩)的岩石学和地球化学分析结果。样品集记录了三个主要的熔岩反应事件,涉及具有前弧玄武岩(FAB)样、倭黑岩和过渡成分的熔体。渭长岩和辉长岩的成分更趋向于过渡性玄武岩成分,其余的则更趋向于倭黑质成分。这三个事件在一个样品(wehrlite D31-106)中的交叉出现,确定了事件发生的相对时间,就像所报道的博宁海脊火山大厦的发生时间一样,博宁海脊在俯冲开始时(约 51-52 Ma)从弧前玄武岩火山活动过渡到俯冲系统成熟时的倭黑质火山活动(约 50-51 Ma)。因此,我们认为博宁海脊的下地壳/上地幔转变保留了从俯冲起始时减压熔融产生的FAB熔体到此后弧型通量熔融和倭黑质火山作用转变的记录。样本组中的正长石和两块异常新鲜的哈兹堡岩被认为代表了后来的倭黑质熔融物,可能分别是这类熔融物与残留橄榄岩杂化的结果。后期倭黑石和/或俯冲相关流体与早期形成的FAB相关地壳之间的弥散熔岩反应,通过渭长岩样本D31-106中一个变质矿脉的闪长岩中流体移动元素的富集和第一排过渡金属的贫化记录下来。钨辉石和辉长岩霞石的化学成分表明,它们是从缺乏板块流体特征的含水高贫化熔体中结晶出来的。因此,我们认为高贫化熔体部分可能是在俯冲开始的早期,通过将海水引入原幔楔而产生的。地壳魏长岩和辉长岩总体上类似于FAB的性质表明,大部分下弧地壳是在俯冲起始期间/之后由前弧延伸形成的,后来成熟的弧火山活动可能对前弧外部的下地壳/上地幔记录贡献很少或没有贡献任何物质。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Arc foundations and subduction initiation: Insights into the magmatic evolution of the lower crust/upper mantle of the Izu-Bonin forearc during subduction initiation
Our understanding of the processes at work in the lower crust/upper mantle transition zone during subduction initiation and early arc development has suffered from a general lack of in situ samples. Here, we present the results of petrographic and geochemical analysis of 34 samples (9 harzburgites, 13 dunites, 2 orthopyroxenites, 3 olivine-gabbros, and 7 wehrlites) collected from the inner trench wall of the Bonin Ridge, Izu-Bonin forearc. The sample suite records three main melt-rock reaction events involving melts with forearc basalt (FAB)-like, boninitic, and transitional compositions. The wehrlitic and gabbroic rocks trend towards more transitional to FAB compositions and the rest towards more boninitic compositions. The crosscutting occurrence of all three events in a single sample (wehrlite D31-106) establishes a relative timing of the events like that reported for the volcanic edifice of the Bonin Ridge, which transitioned from forearc basalt volcanism at subduction initiation (c.a., 51-52 Ma) to boninitic volcanism (c.a., 50-51 Ma) as the subduction system matured. We therefore suggest that the lower crust/upper mantle transition of the Bonin Ridge preserves a record of the transition from FAB melts created by decompression melting at subduction initiation to arc-type flux melting and boninitic volcanism thereafter. Orthopyroxenites and two anomalously fresh harzburgites from the sample suite are suggested to represent the later boninitic melts and possibly the result of hybridization between such melts and residual peridotites, respectively. Diffuse melt-rock reaction between the later boninites and/or subduction-related fluids and the earlier-formed FAB-related crust is recorded by enrichments in fluid mobile elements and depletions in first row transition metals in clinopyroxenes from a metasomatic vein in wehrlite sample D31-106. The chemistry of the wehrlitic and gabbroic clinopyroxenes suggests that they crystallized from hydrous, highly-depleted melts which lack a slab fluid signature. We thus suggest that highly-depleted melt fractions might be created early on during subduction initiation by the introduction of seawater into the proto-mantle wedge. The overall FAB-like nature of the crustal wehrlites and gabbros would suggest that most of the lower arc crust was created by forearc extension during/following subduction initiation and that later, mature arc volcanism may have contributed little or no material to the lower crust/upper mantle record in the outer forearc.
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
Journal of Petrology
Journal of Petrology 地学-地球化学与地球物理
CiteScore
6.90
自引率
12.80%
发文量
117
审稿时长
12 months
期刊介绍: The Journal of Petrology provides an international forum for the publication of high quality research in the broad field of igneous and metamorphic petrology and petrogenesis. Papers published cover a vast range of topics in areas such as major element, trace element and isotope geochemistry and geochronology applied to petrogenesis; experimental petrology; processes of magma generation, differentiation and emplacement; quantitative studies of rock-forming minerals and their paragenesis; regional studies of igneous and meta morphic rocks which contribute to the solution of fundamental petrological problems; theoretical modelling of petrogenetic processes.
×
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