甘肃北山地区花牛山铅锌矿区玄武岩锆石LA-ICP-MS U-Pb定年及其地质意义  

LA-ICP-MS zircon U-Pb dating of basalt and its geological significance in Huaniushan Pb-Zn deposit,Beishan area,Gansu,China

作　　者：杨建国[1] 翟金元 杨宏武 王冲峰 谢春林[1] 王小红[1] 雷永孝[1] 

机构地区：[1]中国地质调查局西安地质矿产研究所,陕西西安710054 [2]甘肃西脉新材料科技股份有限责任公司,甘肃瓜州750021

出　　处：《地质通报》2010年第7期1017-1023,共7页Geological Bulletin of China

基　　金：全国危机矿山接替资源找矿预测项目<甘肃省安西县花牛山金银铅锌矿矿产预测>(编号:200662062)资助

摘　　要：位于甘肃北山瓜州县境内的花牛山银铅锌矿是北山地区唯一的喷流(气)沉积型块状硫化物矿床,它赋存于一套浅变质细碎屑岩或中基性火山岩夹碎屑岩-碳酸盐岩建造中。关于该矿床的成矿时代,因无确切的同位素年代学和化石证据,争议较大。对花牛山银铅锌矿三矿区铅锌矿体的赋矿围岩玄武岩样品中的锆石进行了LA-ICP-MS法U-Pb定年研究,获得了207Pb/206Pb年龄1071Ma±5Ma,表明花牛山地区中基性火山喷溢活动发生在晚蓟县世。进而揭示花牛山银铅锌矿床是蓟县纪末期强烈拉张构造环境下,与海底火山喷溢活动相伴随的热液活动的产物。它与北山红山铁矿和东天山彩霞山,北祁连山西段石硐沟,华北地块西北缘东升庙、炭窑口、霍各乞等层控铅锌多金属矿床具可对比性,蓟县纪末期是北山地区一个重要的成矿时期。The Huaniushan Ag-Pb-Zn deposit is located in the Guazhou County, Beishan Mountain of Gansu Province. It is the only massive sulfide deposit of SEDEX type in Beishan Mountain, which occurred in the construction of light metamorphic clastic rocks or intermediate-basic volcanic rocks interbed clastic rocks-carbonate rocks. Without of the exact evidences about the isotopic geochronology and fossils, the metallogenlc age of the deposit was disputed. The LA-ICP-MS zircon dating of basalt in the three ore area is researched, with 1071±5Ma. It is suggested that the expulsion activities of intermediate basic volcanic rocks in Huaniushan happened at late Jx era, and further showed that the Ag-Pb-Zn deposit formed in the extensional environment at the end of Jx period, related to the submarine volcanic action with the hydrothermal activities. It is compared with the some layer-controlled Pb-Zn polymetallic deposits, such as Hongshan Fe deposit in Beishan Mountain, Caixiashan Pb-Zn deposit in East Tianshan Mountain, Shidonggou deposit in the west segment of North Qilian Mountain and Dongshengmiao, Tanyaokou, Huogeqi deposits in the northwestern margin of the North China block. It is representative of the important mineralization period in the Beishan Mountain.

关 键 词：银铅锌矿床 玄武岩 锆石LA—ICP-MS测年 甘肃北山地区 

分 类 号：P597.3[天文地球—地球化学]