地质学报2017，Vol.91Issue(4)：762-775,14.
新疆维宝多金属矿区辉绿岩脉SIMS年代学和地球化学
SIMS Chronology and Geochemistry of Diabase Dykes from the Weibao Polymetallic Orefield, Xinjiang
摘要
Abstract
The East Kunlun Orogenic Belt is characterized by intense Hercynian-Indosinian magmatic activities,with widespread intermediate-felsic intrusions as well as large numbers of diabase dykes.Compared to the research of intermediate-acid intrusions,however,less focus has been put to that of dabase dykes.In this study,a systematical research has been done to the chronology and geochemistry of mafic dykes,which determined the emplacement age,the tectonic setting as well as the petrogenesis of diabase.SIMS zircon U-Pb dating indicated that these dykes were formed in 227.5±3.3 Ma (1σ,MSWD =2.0) belonging to late Triassic,which well constrains the upper limit of emplacement of ore-forming intrusions.Combined with our unpublished age data,a time span between 232Ma and 227.5Ma was further proposed to limit emplacement time of the ore-forming intrusion of the Weibao skarn copper-lead-zinc deposit.The major elements of diabase in the Weibao deposit are characterized by high SiO2 and K2O,and low MgO,Al2O3,CaO,FeO and Na2O,illustrating that most samples are calc-alkaline rocks.The light and heavy rare earth elements (REE)are characterized by high fractionation,with LaN/YbN＞5 and most δEu ranging from 0.73 to 0.77;therefore,in the chondrite-normalized REE diagram,most samples are typical of right-dipping REE distributions with noticeable negative Eu anomaly;in the trace element spider diagram,these diabase selectively enriched LILE(e.g.,LREE)and depleted HFSE(e.g.,Ti,P).In spite of these arc-like features showed by geochemical compositions of diabase,we argue that diabase in the Weibao deposit formed in a post-collision environment;the arc-like features were probably derived from the enrichment by early subduction materials.In late Indosinian,upderplating of mantle-derived magmas caused the partial melting of lower crust that produced felsic magmas;two source magmas mixed during rising and finally formed granodiorite and diabase sharing similar ages as well as rare earth and trace element compositions.关键词
恽绿岩/SIMS/矽卡岩矿床/维宝/祁漫塔格/东昆仑Key words
diabase/SIMS/skarn deposit/Weibao/Qiman Tagh/East Kunlun引用本文复制引用
钟世华,丰成友,李大新,赵一鸣,周建厚,刘建楠,王辉,于淼..新疆维宝多金属矿区辉绿岩脉SIMS年代学和地球化学[J].地质学报,2017,91(4):762-775,14.基金项目
本文为国土资源部公益性行业科研专项经费项目(编号:201411025)、中国地质调查局地质调查项目(编号:1212011085528)、中国地质调查局高层次地质人才培养计划(编号:201309)和青年地质英才计划(编号:201112)资助的成果. （编号:201411025）
