吉林东部汪清县九三沟金矿区石英闪长玢岩U-Pb年代学和地球化学特征  

Zircon U-Pb Age and Geochemistry of Quartz Diorite Porphyrite in the Jiusangou Gold Deposit, Wangqing, Eastern Jilin Province

作　　者：张晓秋[1,2] 李碧乐[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130026 [2]吉林省地质勘查基金管理中心,吉林长春130061

出　　处：《大地构造与成矿学》2016年第3期603-613,共11页Geotectonica et Metallogenia

基　　金：中国地质调查局计划项目(资[2011]02-36-06);国家自然科学基金项目(41272093);吉林省科技发展计划重点项目(20100445)联合资助

摘　　要：九三沟金矿区石英闪长玢岩在火山盆地内呈脉状或岩株状产出,与金矿化空间上密切伴生。本文通过岩石地球化学和LA-ICP-MS锆石U-Pb年代学研究,讨论了石英闪长玢岩的成因、源区和构造背景,厘定了成岩时代。研究表明,九三沟石英闪长玢岩属于钙碱性、过铝质系列岩石,富集大离子亲石元素(Ba、Sr)、活泼的不相容元素Th、U和轻稀土元素,亏损高场强元素Ta、Nb、Ti和重稀土元素。岩石的Nb/Ta、La/Nb、Th/La比值都显示其具壳源特征,在Al_2O_3-MgO-FeO_t和R1-R2判别图解上均表现为活动大陆边缘岩浆岩特征。石英闪长玢岩LA-ICP-MS锆石U-Pb年龄为104.2±1.4 Ma,MSWD=0.17,为早白垩世晚期(燕山晚期),形成于太平洋板块斜向俯冲引起的东亚大陆走滑伸展的构造环境。而吉黑东部中生代浅成低温热液成矿作用与该期钙碱性–碱性火山岩–浅成浅成侵位活动密切相关,因此早白垩世晚期的火山机构和浅成钙碱性–碱性侵入体是吉黑东部中生代浅成低温热液的找矿目标。The quartz diorite porphyrite in the Jiusangou gold deposit, which is closely associated with mineralization, occurs as dyke or stock in a volcanic basin. Based on the studies of geochemistry, LA-ICP-MS zircon U-Pb age, this paper mainly discusses the age, petrogenesis, source, and tectonic setting of the porphyrite. It was shown that the Jiusangou quartz diorite porphyrite belongs to calc-alkaline and metaluminous-weakly peraluminous series, and is enriched in LILE（such as Ba、Sr）, incompatible elements（such as Th, U）, LREE, and depleted in HFSE（such as Nb, Ta, Ti, P） and HREE. Nb/Ta, La/Nb, Th/La ratios and diagram of La/Nb vs. Ba/Nb suggest that the quartz diorite porphyrite was mainly derived from the crust. In the Al2O3-MgO-FeOt diagram and R1 vs. R2 diagram, the quartz diorite porphyrite is characterized by arc-type active continental affinity. LA-ICP-MS zircon U-Pb of the quartz diorite porphyrite yielded weighted average age of 104.2±1.4 Ma（MSWD=0.17） and concordant age of 103.7±0.6 Ma（MSWD=4.4）, which is of Late Yanshania（late of Early Cretaceous）. It was argued that the mineralization occurred in the slip-extensional environment in the East Asian continent that was caused by the oblique subduction of the Pacific plate during the Late Yanshanian. The volcanic edifices and small scale hypabyssal calc-alkaline and alkaline intrusive bodies, which were generated in the continental arc extensional setting in the late of Early Cretaceous, are the main targets for the prospecting of epithermal deposits in the east Jilin-Heilongjiang province.

关 键 词：岩石地球化学 锆石U-PB测年 石英闪长玢岩 九三沟 吉林东部 

分 类 号：P597[天文地球—地球化学] P595[天文地球—地质学]