Apatite U–Pb geochronology and whole rock, Sr–Nd–Pb isotopic geochemistry of XV mafic-ultramafic intrusion, Bafq, Central Iran: Implications for petrogenesis and tectonic setting

IF 1 4区地球科学 Q4 GEOSCIENCES, MULTIDISCIPLINARY

Island Arc Pub Date : 2024-02-17 DOI:10.1111/iar.12514

Sakine Amraei, Mohammad Yazdi, Liang Qiu, Chang-Zhi Wu, Lei Chen, Bertrand Moine, Majid Ghasemi Siani, Qihui Zhang, Shahrokh Rajabpour

{"title":"Apatite U–Pb geochronology and whole rock, Sr–Nd–Pb isotopic geochemistry of XV mafic-ultramafic intrusion, Bafq, Central Iran: Implications for petrogenesis and tectonic setting","authors":"Sakine Amraei, Mohammad Yazdi, Liang Qiu, Chang-Zhi Wu, Lei Chen, Bertrand Moine, Majid Ghasemi Siani, Qihui Zhang, Shahrokh Rajabpour","doi":"10.1111/iar.12514","DOIUrl":null,"url":null,"abstract":"The XV mafic-ultramafic intrusion is located in the western part of the Posht-e-Badam Block (PBB) within the Central Iranian Micro-Continent (CIMC). Petrographically, the intrusion is composed of gabbro and pyroxenite. Apatite U–Pb dating has established the crystallization age of this intrusion to be 363 ± 67 Ma. The XV intrusive rocks are tholeiitic to slightly calc-alkaline in nature and are characterized by an enrichment of large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE) and Heavy Rare Earth Elements (HREE), respectively. The major oxide elements display continuous trends relative to SiO2. The 87Sr/86Sr(i) ratios range from 0.7045 to 0.7056, and the εNd(i) values range from 2.63 to 3.30. In addition, the 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios exhibit a narrow range, varying from 18.68 to 18.70, 15.67 to 15.71, and 38.84 to 38.99, respectively. The geochemical and isotopic characteristics suggest that the parental magma was derived from a Sub- Continental Lithospheric Mantle (SCLM) that was modified by oceanic slab-derived components. The locations of the XV intrusive rocks in εNd(i) versus TDM (Ga) and Nb/La versus discrimination diagrams further support this conclusion. Fractional crystallization is identified as the dominant process influencing the formation of distinct lithological units within the XV intrusive rocks. Our newly presented isotopic and geochronological data, when considered in the regional context, suggest that the XV intrusive rocks were formed in an extensional tectonic setting. In this scenario, upwelling from the asthenospheric mantle induced heating, leading to the melting of previously subduction-modified SCLM. Comparative analysis with previously published ages indicates that extensional magmatism in the PBB continued into the Middle Paleozoic.","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"33 1","pages":""},"PeriodicalIF":1.0000,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Island Arc","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/iar.12514","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

The XV mafic-ultramafic intrusion is located in the western part of the Posht-e-Badam Block (PBB) within the Central Iranian Micro-Continent (CIMC). Petrographically, the intrusion is composed of gabbro and pyroxenite. Apatite U–Pb dating has established the crystallization age of this intrusion to be 363 ± 67 Ma. The XV intrusive rocks are tholeiitic to slightly calc-alkaline in nature and are characterized by an enrichment of large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE) and Heavy Rare Earth Elements (HREE), respectively. The major oxide elements display continuous trends relative to SiO₂. The ⁸⁷Sr/⁸⁶Sr(i) ratios range from 0.7045 to 0.7056, and the εNd(i) values range from 2.63 to 3.30. In addition, the ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios exhibit a narrow range, varying from 18.68 to 18.70, 15.67 to 15.71, and 38.84 to 38.99, respectively. The geochemical and isotopic characteristics suggest that the parental magma was derived from a Sub- Continental Lithospheric Mantle (SCLM) that was modified by oceanic slab-derived components. The locations of the XV intrusive rocks in εNd(i) versus TDM (Ga) and Nb/La versus discrimination diagrams further support this conclusion. Fractional crystallization is identified as the dominant process influencing the formation of distinct lithological units within the XV intrusive rocks. Our newly presented isotopic and geochronological data, when considered in the regional context, suggest that the XV intrusive rocks were formed in an extensional tectonic setting. In this scenario, upwelling from the asthenospheric mantle induced heating, leading to the melting of previously subduction-modified SCLM. Comparative analysis with previously published ages indicates that extensional magmatism in the PBB continued into the Middle Paleozoic.

查看原文本刊更多论文

伊朗中部巴夫克 XV 黑云母-超黑云母侵入体的磷灰石 U-Pb 地质年代和全岩 Sr-Nd-Pb 同位素地球化学：对岩石成因和构造背景的影响

十五号黑云母-超黑云母侵入体位于伊朗中部微大陆（CIMC）的波什特-巴达姆区块（Posht-e-Badam Block）西部。从岩石学角度看，该侵入体由辉长岩和辉绿岩组成。根据磷灰石 U-Pb 测定法，该侵入体的结晶年龄为 363 ± 67 Ma。十五号侵入岩为透辉石质至轻微钙碱性，其特征是大离子亲岩元素（LILE）和轻稀土元素（LREE）分别富集于高场强元素（HFSE）和重稀土元素（HREE）。主要氧化物元素相对于二氧化硅显示出连续的趋势。87Sr/86Sr(i) 比值范围为 0.7045 至 0.7056，εNd(i) 值范围为 2.63 至 3.30。此外，206Pb/204Pb、207Pb/204Pb 和 208Pb/204Pb 的比值范围较窄，分别为 18.68 至 18.70、15.67 至 15.71 和 38.84 至 38.99。地球化学和同位素特征表明，母体岩浆来源于次大陆岩石圈地幔（SCLM），并经过大洋板块衍生成分的改造。XV侵入岩在εNd（i）与TDM（Ga）和Nb/La与判别图中的位置进一步支持了这一结论。碎裂结晶被认为是影响 XV 侵入岩内部不同岩性单元形成的主要过程。我们新提供的同位素和地质年代数据，结合区域背景来看，表明 XV 侵入岩是在伸展构造环境中形成的。在这种情况下，来自天体层地幔的上涌诱导了加热，导致了先前经俯冲改造的 SCLM 的熔化。与以前公布的年龄进行的比较分析表明，PBB地区的伸展岩浆活动一直持续到中古生代。

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分钟内获得全文求助全文

来源期刊

Island Arc 地学-地球科学综合

CiteScore

2.90

自引率

26.70%

发文量

审稿时长

>12 weeks

期刊介绍： Island Arc is the official journal of the Geological Society of Japan. This journal focuses on the structure, dynamics and evolution of convergent plate boundaries, including trenches, volcanic arcs, subducting plates, and both accretionary and collisional orogens in modern and ancient settings. The Journal also opens to other key geological processes and features of broad interest such as oceanic basins, mid-ocean ridges, hot spots, continental cratons, and their surfaces and roots. Papers that discuss the interaction between solid earth, atmosphere, and bodies of water are also welcome. Articles of immediate importance to other researchers, either by virtue of their new data, results or ideas are given priority publication. Island Arc publishes peer-reviewed articles and reviews. Original scientific articles, of a maximum length of 15 printed pages, are published promptly with a standard publication time from submission of 3 months. All articles are peer reviewed by at least two research experts in the field of the submitted paper.