河南沙坡岭矿床位于华北克拉通南缘的熊耳地体,产在燕山期花岗岩与围岩太华超群的外接触带,为东秦岭最近发现的细脉浸染型钼矿床.矿体受断裂或围岩裂隙控制,呈细脉、网脉状产出,矿石类型包括细脉状、浸染状和块状.为确定沙坡岭钼矿床成矿时代,本文利用辉钼矿Re-Os同位素定年,研究表明:采集的6件辉钼矿样品Re-Os单样年龄为158.3±1.5～160.7±1.2 Ma,其加权平均值为160±1 Ma(2σ误差,MSWD=2.1),指示沙坡岭钼矿化发生于晚侏罗世,且早于花山岩基约30 Ma,指示与花岗岩基无关.另外,一件产于花山复式岩体的团块状辉钼矿样品Re-Os单样年龄为130.5±1.0 Ma,与赋矿的花山岩体成岩时代一致,同样与前人报道的辉钼矿年龄(125.4 ～ 129.4 Ma)基本一致,且不存在明显的单颗粒辉钼矿187Os迁移,表明部分钼矿化形成于早白垩世.因此,辉钼矿Re-Os同位素定年显示沙坡岭矿床存在晚侏罗世和早白垩世两期钼矿化.结合矿床地质特征、成矿构造演化,认为沙坡岭钼矿与熊耳地体的花山岩基、花岗斑岩以及相关热液矿床,均属于秦岭造山带陆陆碰撞过程中挤压向伸展转变体制的产物.%The Shapoling Mo deposit is located in the Xiong'er rock mass of the southern margin of the North China Craton.The deposit is hosted in a contact zone between granite and wallrocks of the Taihua Soupergroup,which is a recently found discovered vein dissemination type deposit in East Qinling.The ore-bodies are associated with quartz veins and controlled by subsidiary faults.The mineralization styles include veinlet and disseminated types.In order to determine the age of the Shapoling Mo deposit,Re-Os isotopic dating of molybdenite was conducted.Six molybdenite samples yielded Re-Os ages ranging from 158.3 ± 1.5 Ma to 160.7 ± 1.2 Ma,with a weighted mean age of 160 ± 1 Ma (2σ,MSWD =2.1).The Re-Os age shows that the Mo mineralization occurred during the late Jurassic,earlier than the formation of Huashan rock mass (about 30 Ma).In addition,one molybdenite sample in Huashan rock mass yielded a Re-Os age of 130.5 ± 1.0 Ma,which is in accordance with the age of the Huashan pluton and molybdenite age (125.4-129.4 Ma) reported by a previous study.In conclusion,the Shapoling deposit contains two episodes of Mo mineralization from the early Cretaceous and late Jurassic periods.Combining this with geological characteristics and tectonic-metallogenic evolution,it is suggested that Huashan rock mass,granite porphyry,and related hydrothermal deposits in the Xiong'er terrain are the products of extrusion to extension transition during continent-continent collision in the Qinling orogenic belt.
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