北山地区清白山铅锌矿赋矿地层年代学研究及对增生造山过程的制约  

Geochronology of Ore Bearing Strata of Qingbaishan Pb-Zn Deposit in Beishan Area and Its Constraints on Accretionary Orogeny

作　　者：赵同阳 郑加行 韩琼 靳刘圆 孙耀峰 陈晔 Zhao Tongyang;Zheng Jiaxing;Han Qiong;Jin Liuyuan;Sun Yaofeng;Chen Ye(Xinjiang Institute of Geological Survey,Urumqi,Xinjiang,830000,China)

机构地区：[1]新疆维吾尔自治区地质调查院,新疆乌鲁木齐830000

出　　处：《新疆地质》2021年第4期553-562,共10页Xinjiang Geology

基　　金：国家重点研发计划东天山阿齐山-清白山铜铅锌矿带深部资源预测课题(2018YFC0604005);新疆维吾尔自治区区域地质志(DD19-23);新疆区域地质志、矿产志研编(Y19-1-XJ001)共同资助。

摘　　要：清白山铅锌矿位于中亚造山带中段南缘北山增生造山带内,赋矿地层为绿片岩相-低角闪岩相变质岩系,对该套变质岩系的详细研究有助于进一步解析北山地区增生造山过程。通过碎屑锆石LA-ICP-MS U-Pb测年数据,从原长城系中解体出沉积下限为新元古代南华纪(733.7±6.0 Ma)的副变质岩、成岩年龄下限为早寒武世(517.6±5.2 Ma)的变质火山-沉积岩系。岩石整体上富集K_(2)O、Al_(2)O_(3)、SiO_(2),稀土分布曲线具明显右倾特征。样品富集大离子亲石元素、亏损高场强元素,认为该套变质岩形成于大陆边缘环境,非全部形成于中元古代,其中混杂有新元古代、早古生代地质体。矿区首次发现晚奥陶世(454.5±7.1 Ma)隐伏的二长岩侵入体,地球化学特征显示属准铝质碱性钾质岩石系列,侵位于增生楔环境中,形成于后碰撞阶段。结合区域前人研究成果,提出新的增生造山模型。认为北山增生造山带形成于混杂有前寒武纪变质基底的多岛弧盆俯冲-增生体系,中晚奥陶世至二叠纪经历了明显的地壳生长,最终增生造山作用结束于早二叠世晚期。The Qingbaishan Pb-Zn deposit is located in the Beishan accretionary orogenic belt on the southern margin of the Central Asian orogenic belt,the ore bearing strata are metamorphic rock series of greenschist facies and low amphibolite facies,a detailed study of the metamorphic series will be helpful to further understand the accretionary orogenic process in Beishan area.Based on the LA-ICP-MS U-Pb dating data of detrital zircon,Neoproterozoic parametamorphic rocks(733.7±6.0Ma)and metamorphic volcanic sedimentary rock series of early Cambrian(517.6±5.2Ma)were disintegrated from Mesoproterozoic strata,the rocks are rich in K_(2)O,Al_(2)O_(3) and SiO_(2),The distribution curve of REE has obvious right inclination,the samples are enriched in large ion lithophile elements and depleted in high field strength elements,it is considered that the metamorphic rocks were formed in the continental margin environment,and not all of them were formed in Mesoproterozoic,it also includes Neoproterozoic and early Paleozoic geological bodies.The late Ordovician(454.5±7.1Ma)concealed monzonite intrusion is discovered for the first time in the study area,geochemical characteristics show that it belongs to paraaluminous alkaline potassic rock series,formed in the post collision phase.A new accretionary orogenic model is proposed based on the previous research results,it is considered that the Beishan orogen was formed in the subduction accretionary system of multi island arc mixed with Precambrian metamorphic basement,and experienced obvious crustal growth from middle Late Ordovician to Permian,and finally ended in Early Permian.

关 键 词：北山造山带 清白山铅锌矿 地质年代学 增生造山 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]