广东大宝山多金属矿床两期成矿:来自黑色炭质泥岩和辉钼矿Re-Os同位素定年的证据  

Two Phases of Mineralization in the Dabaoshan Polymetallic Deposit, Guangdong Province: Constraints from Re-Os Geochronology of Black Carbonaceous Mudstone and Molybdenite

作　　者：向建华 梁新权[1] 单业华[1] 王策[1,2] 董超阁 余世花[1,2] 谭志军 XIANG Jianhua;LIANG Xinquan;SHAN Yehua;WANG Ce;DONG Chaoge;YU Shihua;TAN Zhijun(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Science,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《大地构造与成矿学》2018年第4期732-745,共14页Geotectonica et Metallogenia

基　　金：中国地质调查局地质矿产调查评价专项(12120114015601)、国土资源部公益科研专项(201211024-03)和国家自然科学基金项目(41576040、40872080和41072081)联合资助。

摘　　要：广东省大宝山多金属矿床位于南岭成矿带中段南侧,为多因复成矿床,包括喷流沉积型Cu-Pb-Zn矿床和叠加斑岩-矽卡岩型W-Mo矿床。系统的野外考察发现,喷流沉积型Cu-Pb-Zn矿床主要以层状-似层状、透镜状和角砾状矿体赋存于中泥盆统棋梓桥组,具有典型喷流沉积型矿床特征;斑岩-矽卡岩型W-Mo矿床主要以斑岩型和矽卡岩型矿体围绕大宝山燕山期花岗闪长(斑)岩产出或叠加在喷流沉积形成的层状-似层状矿体之上。对矿区内斑岩-矽卡岩型W-Mo矿床中辉钼矿和喷流沉积型Cu-Pb-Zn矿床中炭质泥岩进行Re-Os同位素定年研究表明,辉钼矿Re-Os等时线年龄为163.6?1.0 Ma(MSWD=0.58),代表了斑岩-矽卡岩型矿床的形成年龄;炭质泥岩Re-Os等时线年龄为387.6?9.9 Ma(MSWD=56),代表同沉积矿床即喷流沉积矿床形成年龄。这反映大宝山多金属矿床至少存在两期重要的成矿事件:斑岩-矽卡岩型W-Mo矿床形成与燕山期中酸性岩浆活动相关,层状-似层状Cu-Pb-Zn矿床形成与海西期海底热液喷流沉积相关。The Dabaoshan polymetallic deposit is a polygenetic composite ore deposit located at south of the Qinhang(Qinzhou-Hangzhou)Metallogenic Belt,which is composed mainly of SEDEX type Cu-Pb-Zn and porphyry-skarn type W-Mo orebodies.Systematic field study shows that the W-Mo mineralization exhibits as quartz-vein type and skarn type orebodies around the granodioritic porphyry,or superimposes on the SEDEX type Cu-Pb-Zn orebody,while the Cu-Pb-Zn mineralization occurs mainly in the Qiziqiao Formation as stratiform-substratiform type and breccia type orebodies with typical SEDEX-type characteristics.Re-Os dating of five molybdenite separates from porphyry-skarn type W-Mo orebodies yielded isochron ages of 163.6±1.0 Ma(MSWD=0.58),which represents the age of W-Mo mineralization.Re-Os dating of seven black carbonaceous mudstone samples from a Cu-Pb-Zn orebody yielded isochron age of 387.6±9.9 Ma(MSWD=56),which is interpreted to be the age of SEDEX-type Cu-Pb-Zn mineralization.These ages indicate that there are at least two stages of ore mineralization in the Dabaoshan polymetallic deposit.The W-Mo mineralization is related to the Yanshanian intermediated-acidic intrusions,while the stratiform-substratiform SEDEX-type Cu-Pb-Zn mineralization is associated with the Hercynian seafloor hydrothermal activities.

关 键 词：大宝山 RE-OS同位素 多因复成矿床 喷流沉积矿床 斑岩型矿床 

分 类 号：P597[天文地球—地球化学] P611[天文地球—地质学]