Experimental Replacement of Zircon by Melt-Mediated Coupled Dissolution-Precipitation Causes Dispersion in U–Pb Ages

IF 3.5 2区 地球科学 Q1 GEOLOGY Journal of Metamorphic Geology Pub Date : 2024-08-27 DOI:10.1111/jmg.12795
Jeremy L. Asimus, Nathan R. Daczko, Jean-Antoine Gazi, Isra S. Ezad, Ivan Belousov, Thomas Rodemann, Jacqueline A. Halpin, Sandra Piazolo
{"title":"Experimental Replacement of Zircon by Melt-Mediated Coupled Dissolution-Precipitation Causes Dispersion in U–Pb Ages","authors":"Jeremy L. Asimus,&nbsp;Nathan R. Daczko,&nbsp;Jean-Antoine Gazi,&nbsp;Isra S. Ezad,&nbsp;Ivan Belousov,&nbsp;Thomas Rodemann,&nbsp;Jacqueline A. Halpin,&nbsp;Sandra Piazolo","doi":"10.1111/jmg.12795","DOIUrl":null,"url":null,"abstract":"<p>Zircon geochronology provides critical information on the rates and durations of geological processes and enables researchers to explore deep time. However, some zircon datasets show a continuum of concordant ages (‘smear’) without well-defined age populations. These age smears are typically interpreted to represent variable loss of radiogenic Pb or protracted geological events lasting tens of millions of years. Coupled dissolution-precipitation replacement of zircon has been suggested as one process that may produce these complex age datasets. Here, we react fragments of the well characterised Mud Tank zircon standard with natural intermediate and mafic melts (0.9 GPa, 1100–1180°C) to test if short-term exposure to a melt can modify the geochronological patterns of zircon. Our observations show that within a short duration (18 h to 3.5 days), most Mud Tank zircon fragments display microstructural and/or chemical evidence for modification by dissolution at fragment boundaries along with partial replacement by coupled dissolution-precipitation processes. The replaced zircon domains have U–Pb ages that smear over one hundred million years, between 764–647 Ma, illustrating variable mobility and redistribution of the U and Pb isotopes. Our experiments demonstrate that zircon modified by coupled dissolution-precipitation replacement may not faithfully record the age or duration of geological events and that investigation of zircon microstructure in high-resolution backscattered electron, cathodoluminescence imaging and/or Raman mapping is needed to better understand complex zircon geochronological datasets.</p>","PeriodicalId":16472,"journal":{"name":"Journal of Metamorphic Geology","volume":"42 9","pages":"1179-1195"},"PeriodicalIF":3.5000,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jmg.12795","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Metamorphic Geology","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/jmg.12795","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0

Abstract

Zircon geochronology provides critical information on the rates and durations of geological processes and enables researchers to explore deep time. However, some zircon datasets show a continuum of concordant ages (‘smear’) without well-defined age populations. These age smears are typically interpreted to represent variable loss of radiogenic Pb or protracted geological events lasting tens of millions of years. Coupled dissolution-precipitation replacement of zircon has been suggested as one process that may produce these complex age datasets. Here, we react fragments of the well characterised Mud Tank zircon standard with natural intermediate and mafic melts (0.9 GPa, 1100–1180°C) to test if short-term exposure to a melt can modify the geochronological patterns of zircon. Our observations show that within a short duration (18 h to 3.5 days), most Mud Tank zircon fragments display microstructural and/or chemical evidence for modification by dissolution at fragment boundaries along with partial replacement by coupled dissolution-precipitation processes. The replaced zircon domains have U–Pb ages that smear over one hundred million years, between 764–647 Ma, illustrating variable mobility and redistribution of the U and Pb isotopes. Our experiments demonstrate that zircon modified by coupled dissolution-precipitation replacement may not faithfully record the age or duration of geological events and that investigation of zircon microstructure in high-resolution backscattered electron, cathodoluminescence imaging and/or Raman mapping is needed to better understand complex zircon geochronological datasets.

Abstract Image

查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
熔融介导的溶解-沉淀耦合实验置换锆石导致 U-Pb 年代的分散
锆石地质年代学提供了有关地质过程的速率和持续时间的重要信息,使研究人员能够探索深部时间。然而,一些锆石数据集显示出连续的一致年龄("涂抹"),而没有明确的年龄群。这些年龄斑点通常被解释为放射性铅的可变损失或持续数千万年的漫长地质事件。锆石的溶解-沉淀耦合置换被认为是产生这些复杂年龄数据集的一个过程。在这里,我们将特性良好的泥潭锆石标准碎片与天然的中间熔体和岩浆熔体(0.9 GPa, 1100-1180°C)进行反应,以测试短期暴露于熔体是否会改变锆石的地质年代模式。我们的观察结果表明,在短时间内(18 小时至 3.5 天),大多数泥罐锆石碎片显示出微观结构和/或化学证据,表明碎片边界处的溶解以及溶解-沉淀耦合过程的部分置换改变了锆石。被置换的锆石区域的 U-Pb 年龄在 1 亿年(764-647 Ma)之间,说明了 U 和 Pb 同位素的可变流动性和再分布。我们的实验表明,通过溶解-沉淀耦合置换改变的锆石可能无法忠实地记录地质事件的年龄或持续时间,因此需要通过高分辨率反向散射电子、阴极发光成像和/或拉曼绘图来研究锆石的微观结构,以便更好地理解复杂的锆石地质年代数据集。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 去求助
来源期刊
CiteScore
6.60
自引率
11.80%
发文量
57
审稿时长
6-12 weeks
期刊介绍: The journal, which is published nine times a year, encompasses the entire range of metamorphic studies, from the scale of the individual crystal to that of lithospheric plates, including regional studies of metamorphic terranes, modelling of metamorphic processes, microstructural and deformation studies in relation to metamorphism, geochronology and geochemistry in metamorphic systems, the experimental study of metamorphic reactions, properties of metamorphic minerals and rocks and the economic aspects of metamorphic terranes.
期刊最新文献
Issue Information Zircon Coupled Dissolution–Precipitation Replacement During Melt–Rock Interaction Modifies Chemical Signatures Resulting in Misleading Ages Pressure–Temperature–Time Evolution of a Polymetamorphic Paragneiss With Pseudomorphs After Jadeite From the HP–UHP Gneiss-Eclogite Unit of the Variscan Erzgebirge Crystalline Complex, Germany Issue Information Experimental Replacement of Zircon by Melt-Mediated Coupled Dissolution-Precipitation Causes Dispersion in U–Pb Ages
×
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
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 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 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1