西秦岭寨上金矿床中石英和绢云母^(40)Ar/^(39)Ar定年  

^(40)Ar/^(39)Ar dating of alteration minerals from Zhaishang gold deposit in Minxian County,Gansu Province,and its geological significance

作　　者：路彦明[1] 李汉光[1] 陈勇敢[2] 张国利[2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]武警黄金地质研究所,河北廊坊065000

出　　处：《矿床地质》2006年第5期590-597,共8页Mineral Deposits

基　　金：武警黄金指挥部地质专项资金项目(Hj03-01)资助

摘　　要：寨上金矿是西秦岭地区近年新发现的大型金矿床。为确定该金矿床的成矿时代,对其含金石英、蚀变绢云母进行了40Ar/39Ar快中子活化法测定。2件样品的40Ar/39Ar坪年龄及等时线年龄分别为(130.62±1.38)Ma、(129.24±1.23)Ma和(125.28±1.26)Ma、(125.56±1.20)Ma,测试结果可信。40Ar/39Ar法年龄测定结果表明,寨上金矿床形成于燕山晚期,并可能历经了约5Ma时间最终形成。对西秦岭地区已有的金矿床测年数据进行分析后认为,该区可能存在3个金矿成矿高峰期,即220~170Ma、130Ma前后和50Ma左右。The Zhaishang gold deposit, a large-size gold deposit recently discovered in western Qinling area, belongs to the fine-grained dissemination type. Samples of gold-quartz veins and sericite were determined by ^40Ar/39Ar fastneutron activation techniques. The plateau ages of the two samples are （130.62± 1.38） Ma and （125.28 ± 1.26） Ma, and the isochron ages are （129.24 ± 1.23） Ma and （125.56 ± 1.20） Ma, respectively. The ages of the samples are reliable. According to the results of the ^40Ar/^39Ar dating, the time limit of gold mineralization should be （130.62 ± 1.38） Ma- （ 125.28 ± 1.26） Ma. Statistics of the time limits of fourteen gold deposits including the Zhaishang deposit in western Qinling show that gold mineralization in this area experienced three important ore-forming events, namely, 220-170 Ma, 130 Ma and 50 Ma. The authors hold that the three events were seoarately restrained by three different geodvnamic environments.

关 键 词：地质学 ^40Ar/^39Ar测年 金矿 寨上 西秦岭 

分 类 号：P618.51[天文地球—矿床学]