冈底斯东段羌堆铜钼矿床年代学、矽卡岩石榴石成分及其意义  

Zircon U-Pb Geochronology and Garnet Composition of the Qiangdui Cu-Mo Deposit in the Eastern Section of Gangdese and Their Significances

作　　者：李金祥[1] 秦克章[1] 李光明[1] 林金灯 肖波[1] 江化寨 韩逢杰 黄树峰[2] 陈雷[1] 赵俊兴[1] 

机构地区：[1]中国科学院地质与地球物理研究所中国科学院矿产资源研究重点实验室,北京100029 [2]中国冶金地质勘查工程总局第二地质勘查院,福建莆田351111

出　　处：《地质与勘探》2011年第1期11-19,共9页Geology and Exploration

基　　金：中国冶金地质总局"冈底斯东段南部矽卡岩-斑岩Cu-Au-Mo矿床成矿模式及成矿条件综合研究";国家自然科学基金(编号:40772066)资助

摘　　要：羌堆铜钼矿床是在冈底斯成矿带东段新发现的一处斑岩-矽卡岩型矿床。二长花岗斑岩是该矿床的主要成矿斑岩体,本文用精确的LA-ICP-MS锆石U-Pb定年获得其年龄为16.7±0.9Ma,确定该矿床为中新世成矿,与冈底斯成矿带上驱龙、甲马矿床为同一期成矿事件。对该矿床矽卡岩中石榴石系统研究表明,早期矽卡岩主要以钙铝榴石为主,晚期以钙铁榴石为主;并暗示相应的成矿流体温度和盐度逐渐降低,而氧逸度和pH逐渐升高。另外,部分石榴石含有高含量的F,暗示成矿流体可能富含一定的F。同时,矽卡岩中发育石英-黄铜矿-辉钼矿等脉系,暗示有类似于斑岩型的后期热液活动叠加,以及钻孔中发现岩枝状产出的成矿二长花岗斑岩,综合显示下部有斑岩型矿床找矿前景。The Qiangdui Cu-Mo deposit is a newly discovered porphyry-skarn type deposit in the eastern section of the Gangdese metallogenetic belt.Argillic monzogranite porphyry is the major ore-forming rock.In this study,ore-forming monzogranite porphyry yields the precise LA-ICP-MS zircon U-Pb age of 16.7±0.9Ma,confirming this deposit formed in the Miocene.This age indicates that the Qiangdui Cu-Mo deposit belongs to the same metallogenetic event as the Qulong and Tinggong Cu-Mo deposits,Jiama Cu-Pb-Zn deposit in the central Gangdese belt.Additionally,the systematic researches of garnets in the skarn indicate the early-stage skarn is dominated by grossular,and the late-stage skarn is dominated by andradite.This observation also suggests that the salinity and temperature of ore-forming fluid gradually decrease,while oxygen fugacity and pH gradually increase.Besides,partial garnets show high content of F,possibly suggesting the ore-forming fluids have a certain amount of F.It is worth noting that the quartz-chalcopyrite-molybdenite veinlets occur in the skarn,implying they may be superposed by the later hydrothermal activity similar to the porphyry type deposit.Ore-forming monzogranite porphyry apophyses appear in the drill holes.These observations may indicate that there is a prospecting potential of the porphyry type mineralization in the deep subsurface.

关 键 词：LA-ICP-MS锆石U-PB定年 羌堆铜钼矿床 石榴石成分 中冈底斯东段 

分 类 号：P618.65[天文地球—矿床学]