东准噶尔北缘老山口铁-铜-金矿床古生代岩浆岩锆石U-Pb年代学、氧逸度特征及地质意义  

Geochemistry,geochronology and oxygen fugacity of volcanic and intrusive rocks from the Laoshankou Fe-Cu-Au deposit in the northern margin of East Junggar,NW China

作　　者：梁培[1,2] 陈华勇 吴超[1,2] 刘振江[3] LIANG Pei;CHEN Huayong;WU Chao;LIU Zhenjiang(Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;No.4 Geological Party of the Xinjiang Bureau of Geology and Mineral Exploration and Development,Ahay 836500,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]新疆地质矿产开发局第四地质大队,新疆阿勒泰831140

出　　处：《地学前缘》2018年第5期96-118,共23页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2014CB440802);中国科学院交叉学科项目(Y433131A07);中国科学院创新团队国际合作项目(20140491534)

摘　　要：老山口矿床位于新疆东准噶尔北缘,是区域内重要的铁-铜-金矿床。矿区内岩浆岩发育广泛,对其中的奥陶纪玄武安山岩(约449Ma),奥陶纪安山岩(约447Ma),泥盆纪火山岩(393~376Ma)、二长闪长岩(约379Ma)、黑云母闪长岩(约379Ma)、石英正长岩(约376 Ma)、细粒闪长岩(约370 Ma),石炭纪碱性花岗岩(约330Ma)和粗粒闪长玢岩(约310Ma)进行了成岩年代学的统计和测试,结果表明老山口矿床存在3期岩浆活动:450~440Ma、约390~370Ma以及330~310Ma。结合区域构造演化可知,其中450~440 Ma和390~370Ma的岩浆活动形成于不同时期俯冲相关的岛弧环境,而330~310Ma的岩浆活动则形成于后碰撞-板内伸展环境。根据铜-金矿化的时代,可将矿区内的岩浆岩分为3期:成矿前、同成矿及成矿后。老山口同成矿期岩浆岩(泥盆纪火山岩、二长闪长岩、闪长玢岩和黑云母闪长岩)具有相对较高的(Eu/Eu*)N、(Ce/Ce*)N和CeⅣ/CeⅢ值,分别为0.13～0.86、1.14～445.92和33.34～1 165.04,说明铁-铜-金矿化与高氧逸度的岩浆活动有关。The Laoshankou deposit is an important Fe-Cu-Au deposit in the northern margin of the East Junggar,NW China.LA-ICP-MS U-Pb dating of zircon constrains the timing of crystallization of Ordovician basaltic andesite（-449 Ma）,Ordovician andesite（-447 Ma）,Devonian volcanic rocks（393-376 Ma）,monzodiorite（-379 Ma）,biotite diorites（-379 Ma）,quartz syenites（-376 Ma）,fine-grained diorite（-370 Ma）,alkali granite（-330 Ma）and coarse-grained diorite porphyry（-310 Ma）.Zircon dating indicates three periods of magmatism in Laoshankou：450-440 Ma,-390-370 Ma and 330-310 Ma.The magmatism for the first two periods occurred in a subduction-related island arc setting;the magmatism for the last one occurred in a post-collision or inplate extensive setting.Pre-,syn-and post-mineralization volcanic and intrusive rocks are divided based on the Fe-Cu-Au mineralization timing.Syn-mineralization intrusions in Laoshankou have relatively high（Eu/Eu＊）N,（Ce/Ce＊）Nand CeIV/CeIII values of 0.13-0.86,1.14-445.92 and 33.34-1165.04,respectively,indicating Fe-Cu-Au mineralization was associated with high oxygen fugacity magmatism.

关 键 词：东准噶尔北缘 老山口铁-铜-金矿床 锆石U-PB年代学 锆石微量元素 氧逸度 

分 类 号：P618.31[天文地球—矿床学] P618.41[天文地球—地质学]