内蒙古赤峰南窝铺铀矿床英安岩的SHRIMP锆石U-Pb年龄、地球化学特征及地质意义

南窝铺铀矿床位于西拉木伦缝合带以南、康宝—围场—赤峰断裂带(华北北缘断裂带的一部分)以北的白乃庙加里东期岛弧带和华北古板块北缘海西期俯冲—碰撞带,属沽源—红山子铀成矿带北东段红山子—广兴铀成矿亚带的一个铀矿床,铀矿体赋存在额里图组安山岩—英安岩—流纹岩组合中.该组合中的英安岩SHRIMP锆石n(206Pb)/n(238...

SHRIMP zircon U-Pb ages,geochemical characteristics and tectonic significance of dacite from the Nanwopu uranium deposit,Chifeng,Inner Mongolia

Objectives:The Nanwopu uranium deposit is located in the northeastern section of the Guyuan—Hongshanzi uranium metallogenic belt.Dacite,which belongs to Elitu Formation,is the direct surrounding rock of the Nanwopu uranium deposit.The aim of this paper is to investigate the petrogenesis and tectonic significance of this rock suite.Methods:Detailed geological survey,SHRIMP zircon U-Pb dating and whole-rock major and trace elements were carried out on the Nanwopu dacite in this paper.Results:The SHRIMP zircon U-Pb dating of the Nanwopu dacite is 268.1±2.5 Ma,it can be ascertained that the dacites are the products of Early Permian magmatic activities.The whole-rock geochemical analyses show that the Nanwopu dacite lie in middle K calc-alkaline fields,the Aluminium saturation index show the metalumininous and weak peraluminous features,integrated with enrichments of LREE and LILE(Rb,Ba,Th,K),depletions of Nb,Ta,P and Ti and Eu negative anomaly,belongs to I-type granites,suggesting plate subduction-related geochemical affinities.Conclusions:Combined with the regional studies,the above geochemical signatures indicate that the Nanwopu dacite was formed in the volcanic arc tectonic environment on the active continental margin of the Hercynian tectonic stage(north margin of North China Craton).This is inconsistent with the tectonic environment drew from the other Mesozoic uranium deposits related to volcanic rocks in eastern China.The Lower Permian Erlitu Formation is favorable for the occurrence of uranium mineralization in eastern China.