投稿时间：2022-09-20
修订日期：2023-04-24
网络发布日期：2023-07-08
中文摘要:年代学研究是花岗岩型稀有金属矿床研究的重要内容，多种定年方法的联合有助于对岩浆演化及稀有金属元素富集成矿过程的精细刻画。论文选择栗木矿区具代表性的金竹源、老虎头和水溪庙花岗岩型钨锡铌钽矿床和（长石）石英脉型钨锡矿床，进行LA-ICP-MS锆石U-Pb和LA-MC-ICP-MS锡石U-Pb年代学研究。结果显示，老虎头细粒铁锂云母钠长石花岗岩锆石U-Pb年龄为（216.3±1.7）Ma，长石石英脉型钨锡矿床锡石UPb年龄为（210.1±4.9）Ma；两件金竹源花岗岩型钨锡铌钽矿床锡石U-Pb年龄分别为（219.6±1.5）Ma和（219.9±2.2）Ma，石英脉型钨锡矿床锡石U-Pb年龄为（217.3±3.2）Ma；水溪庙长石石英脉型钨锡矿床锡石U-Pb年龄为（210.7±2.5） Ma。本次研究可以看出，金竹源花岗岩的成岩年龄与花岗岩型钨锡铌钽矿床及石英脉型钨锡矿床的成矿年龄间隔较小，表明含矿花岗岩可能在较短时间内经历了岩浆冷凝结晶、富集成矿和热液锡矿化过程，是短暂矿化事件的产物，而非以往认为的岩浆-热液长时间演化的结果。同时，基于不同测年方法的对比结果显示，在含锡花岗岩中，锡石年龄既能代表锡矿的成矿年龄，也能代表花岗岩的结晶年龄；花岗岩中未受蚀变的锆石年龄和锡石年龄基本一致，但锆石蜕晶化后经流体交代作用及重结晶作用导致U-Pb同位素系统重置的时间普遍晚于实际成岩年龄。
Abstract:Geochronological dating is a vital part of the study of granitic pegmatite type rare-metal deposits. Multiple dating methods combined can constrain the age of intrusion-forming and rare metal mineralization precisely, which can promote the meticulous depiction of magma evolution and rare metal elements enrichment. In this study, we report new dating results of zircon and cassiterite from the Jinzhuyuan, Laohutou, and Shuiximiao granite-type W-Sn-Nb-Ta deposits and quartz vein-type W-Sn deposits. The dating results show that the zircon U-Pb age of Laohutou pluton is (216.3±1.7)Ma, cassiterite U-Pb age of the Laohutou feldspar quartz vein-type W-Sn deposit is (210.1 ± 4.9)Ma; the cassiterite U-Pb age of the Jinzhuyuan granite-type W-Sn-Nb-Ta deposit ranges from (219.6±1.5)Ma to (219.9±2.2)Ma, the cassiterite U-Pb age of the quartz vein-type W-Sn deposit is slightly younger (217.3 ± 3.2)Ma; the cassiterite U-Pb age of the Shuiximiao feldspar quartz vein-type W-Sn deposit is (210.7±2.5)Ma. Based on this study, we found the time gap between granitic magmatism, granite type tin-polymetallic mineralization and hydrothermal mineralization in Jinzhuyuan is quite short, and no long-lived process needs to be involved. The W-Sn polymetallic deposit is the product of a short-lived mineralizing event. Based on the comparison of different dating methods, the U-Pb ages of cassiterite might represent both ore-forming age of tin deposit and the age of ore-bearing granite intrusions, the age of fresh zircon in granite is basically consistent with the age of cassiterite, whereas the U-Pb age of metamict zircon is younger which could record a reset time of U-Pb isotope system by fluid metasomatism and recrystallization.
keywords:geochemistry LA-ICP-MS zircon U-Pb dating LA-MC-ICP-MS cassiterite U-Pb dating tinpolymetallic deposit Limu Guangxi
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基金项目:本文得到广西自然科学基金项目（编号： 2022GXNSFBA035463、2021GXNSFAA220027，2019GXNSFDA245009）、广西重点研发项目（编号：桂科AB22035045）、国家自然科学基金项目（编号： 42272076、42162008）、国家自然基金项目重大专项（编号： 92162219）、国家重点研发计划项目（编号： 2021YFC2900100）以及广西找矿突破战略行动项目（编号：桂自然资函[2020]1639号）共同资助
引用文本：
潘知博,冯梦,秦亚,冯佐海,康志强,白令安,招传,韩文博.2023.广西栗木锡多金属矿床锆石和锡石U-Pb年龄及其地质意义[J].矿床地质,42(3):481~505PAN ZhiBo,FENG Meng,QIN Ya,FENG ZuoHai,KANG ZhiQiang,BAI LinAn,ZHAO Chuan,HAN WenBo.2023.Zircon and cassiterite U-Pb ages of Limu tin polymetallic ore field in Guangxi and their geological significance[J].Mineral Deposits42(3):481~505
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