赣西北城门山铜多金属矿床矽卡岩的形成时代、物理化学条件及演化过程  

Geochronology and Physical⁃Chemical Conditions of Skarns in Chengmenshan Cu Deposit,Northwestern of Jiangxi Province,Eastern China

作　　者：钟浩 徐耀明 肖炬炜 孔凡斌 Zhong Hao;Xu Yaoming;Xiao Juwei;Kong Fanbin(The Second Geological Brigade,Jiangxi Geological Bureau,Jiujiang 332000,China;School of Earth Resources,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]江西省地质局第二地质大队,江西九江332000 [2]中国地质大学资源学院,湖北武汉430074

出　　处：《地球科学》2025年第2期596-608,共13页Earth Science

基　　金：国家自然科学基金(No.41972085).

摘　　要：为了解赣西北城门山铜多金属矿床的时间格架及矽卡岩形成的物理化学条件和演化过程,利用石榴子石的U-Pb同位素定年、电子探针主量元素分析、LA-ICPMS原位微区微量元素测定等方法,结合矽卡岩整体的TIMA综合矿物分析,获得了146.2±1.1 Ma的年龄,同时发现该矿床的矽卡岩矿物以石榴子石为主,主要为钙铁榴石(And值平均95%),稀土元素具有明显的轻稀土富集,重稀土亏损,Eu正异常的特点.该矿床具有与花岗闪长斑岩和石英斑岩两期岩浆作用对应的两次矽卡岩化热液蚀变及成矿事件,间隔约6~7百万年.强氧化、偏酸性、高盐度、渗滤交代条件下形成了矽卡岩,流体的主要来源为岩浆热液,氧逸度、pH、Cl-浓度存在随体系封闭开放程度及流体通量变化而协同演化的规律.In the purpose of understanding formation time and physical-chemical conditions of skarn in Chengmenshan Cu deposit of northwestern Jiangxi Province,we use garnet to do U-Pb isotopic dating,EPMA major elements analyze and LA-ICPMS trace elements analyze,combined with TIMA automated mineral analyze,the skarn forming age of 146.2±1.1 Ma is acquired,and the mineral composition is mainly garnet(Andradite with And value average 95%),LREE elements are enriched and HREE elements are depleted,and Eu show obviously positive anomalies.Therefore we conclude that Chengmenshan Cu deposit own two times of skarn forming respectively corresponding to the formation of granodiorite porphyry and quartz porphyry.Strong oxidized,acidic,high salinity and advective metasomatism conditions are the environment of skarn forming,and magmatic fluids is the major source of these skarns.The physical-chemical conditions like fO2,pH,Cl-concentration varied systematically with the change of W/R ratio during the formation process of Chengmenshan skarns.

关 键 词：长江中下游成矿带 城门山 矽卡岩 年代学 物理化学条件 地球化学 

分 类 号：P611[天文地球—矿床学]