大兴安岭西坡二道河子铅锌矿床硫化物Rb-Sr、锆石U-Pb年龄及其对构造背景的制约  

Sulfides Rb-Sr and zircon U-Pb ages of the Erdaohezi Pb-Zn deposit in the western slope of the Great Xing’an Range and their constraints on tectonic setting

作　　者：刘艳荣 关强兵[3] 张海东 周群君[1,2] 党顺安 LIU Yanrong;GUAN Qiangbing;ZHANG Haidong;ZHOU Qunjun;DANG Shun’an(School of Earth Science and Resources,Chang’an University,Xi’an 710054,Shaanxi,China;The Laboratory of Mineralization and Dynamics,Chang'an University,Xi’an 710054,Shaanxi,China;Senxin Mining Development Co.Ltd.,Genhe 022357,Inner Mongolia,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]长安大学成矿作用及成矿动力学实验室,陕西西安710054 [3]根河市森鑫矿业开发有限责任公司,内蒙古根河022357

出　　处：《地质通报》2023年第11期1843-1853,共11页Geological Bulletin of China

基　　金：陕西省自然科学基础研究计划项目《黄铁矿原位地球化学对内蒙古甲乌拉矿床两期矿化成因的制约》(编号:2022JM-158);国家自然科学基金青年基金项目《内蒙古二道河子铅锌(银)矿床硫化物原位微量元素和流体包裹体对矿床成因的制约》(批准号:41702062);中央高校基本科研业务费专项资金《内蒙古二道河子铅锌(银)矿床硫化物原位S、Pb同位素组成及地质意义》(编号:300102270203)。

摘　　要：二道河子铅锌矿床位于额尔古纳地块得尔布干成矿带的中段,地处大兴安岭西坡。为有效限制该矿床的成矿时代,对硫化物Rb-Sr年龄和安山玢岩锆石U-Pb年龄开展研究得出:该矿床的内生成矿作用共经历了3个成矿阶段:石英-黄铁矿阶段(Ⅰ)、石英-多金属硫化物阶段(Ⅱ)和石英-方解石-黄铁矿阶段(Ⅲ),其中石英-多金属硫化物阶段是主要的矿化阶段;Ⅲ号矿带主成矿阶段5件闪锌矿和3件黄铁矿的Rb、Sr含量分别为0.081×10^(-6)~2.632×10^(-6)和0.661×10^(-6)~3.186×10^(-6),Rb-Sr同位素等时线年龄为140.8±2.3 Ma,(87 Sr/86 Sr)i值为0.71025~0.71205;与矿体平行、局部切穿矿体的安山玢岩脉的锆石U-Pb年龄为138.8±1.7 Ma。上述结果表明,二道河子矿床为热液脉状铅锌矿床,形成于早白垩世,与次火山岩(安山玢岩)热事件相近。结合前人研究成果,推测成矿与安山质岩浆作用有关,形成于蒙古-鄂霍茨克洋闭合后的伸展环境。The Erdaohezi Zn-Pb deposit is located in the middle segment of the Derbugan metallogenic belt in the Erguna block that is on the western slope of the Great Xing’an Range.Rb-Sr dating for sulfides and U-Pb dating for zircons from the andesitic porphyrite were carried out in order to constrain the mineralization age.Three endogenic mineralization stages have been identified,namely a quartz-pyrite stage(I),a quartz-polymetallic sulfide stage(Ⅱ),and a quartz-calcite-pyrite stage(Ⅲ),of which,the second stage is the main ore-forming stage.The Rb and Sr contents of 5 sphalerites and 3 pyrites formed at the main mineralization stage in the ore beltⅢvary from 0.081×10^(-6)to 2.632×10^(-6)and 0.661×10^(-6)to 3.186×10^(-6),respectively.Accordingly,Rb-Sr isotopic dating of sulfides yields a well-defined isochron age of 140.8±2.3 Ma,close to the zircon U-Pb age(138.8±1.7 Ma)of the andesitic porphyrite crosscutting or parallel to the ore body.The calculated initial 87 Sr/86 Sr ratios range from 0.71025 to 0.71205,which is lower than that of the earth’s crust,but higher than that of mantle.Combined with the previous studies,we suggest that the Erdaohezi deposit is a hydrothermal-vein deposit and is associated with the andesitic magmatism event(andesitic porphyrite).Additionally,mineralization occurred in an Early Cretaceous extensional setting after the closure of the Mongolia-Okhotsk Ocean.

关 键 词：硫化物 Rb-Sr同位素定年 锆石U-Pb同位素定年 铅锌矿床 二道河子 得尔布干成矿带 大兴安岭 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学] P597.3