江西潭港流纹英安岩LA-ICP-MS锆石U-Pb定年及地球化学特征  

LA-ICP-MS zircon U-Pb dating and geochemical characteristics of Tangang rhyodacite in Jiangxi Province

作　　者：张德志[1] 郭福生[1,2] 周万蓬[1,2] 谢财富[1] 刘林清[2] 周佐民[3] 

机构地区：[1]东华理工大学地球科学学院,江西抚州344000 [2]江西省数字国土重点实验室,江西抚州344000 [3]中国地质大学地球科学学院,湖北武汉430074

出　　处：《中国地质》2014年第3期784-796,共13页Geology in China

基　　金：中国地质调查局区调项目(1212011120836);三维地质调查试点项目(1212011220248)联合资助

摘　　要：江西潭港地区流纹英安岩的LA-ICP-MS锆石U-Pb年龄为（136.2±1.5）Ma,属早白垩世火山-岩浆活动产物.其地球化学特征是：富硅（66.82％～68.04％）、高碱（7.56％～7.73％）、高Al2O3（14.91％～15.17％）、准铝—弱过铝质（A/CNK=0.999～1.042）;富集大离子亲石元素和轻稀土元素,亏损高场强元素;稀土元素配分曲线模式图为右倾型,轻重稀土分异程度较高（LREE/HREE的平均值为10.04）,轻稀土内部分馏程度相对重稀土内部分馏程度高,中等程度的Eu负异常（δEu平均值为0.48）.与相山流纹英安（斑）岩形成时代一致,地球化学特征相同,表明两者成岩物质来源相同,属陆壳硅铝层物质重熔演化产物,且为同一岩浆活动产物,即前人所指的相山第一旋回火山活动的产物.通过地质条件对比与分析,笔者认为潭港地区具有一定的铀矿成矿潜力.LA-ICP-MS U-Pb zircon age of rhyodacite in Tangang area of Jiangxi Province is （136.2± 1.5） Ma,belonging to the product of Early Cretaceous volcanic and magrnatic activities.The main geochemical characteristics of the rhyodacite include SiO2=66.82%-68.04%,high alkali （K2O＋Na2O=7.56%-7.73%）,high Al2O3 （14.91%-15.17%）,quasi-aluminous to weakly peraluminous nature （A/CNK=0.999-1.042）,obvious enrichment of LLE and LREE,and relative loss of high field strength elements.The pattern of REE with enriched LREE is a right-oblique curve,with high ratio of LREE/HREE （10.04 in average） and intermediate negative Eu anomalies （the average of δEu is 0.48）.The rhyodacite has comparable formation age and geochemical characteristics with Xiangshan rhyodacite porphyry,which suggests that they are comagmatic products.In addition,these rocks crystallized from the remelted sialic crust,which has been believed to be the first volcanic activity cycle of the Xiangshan rock body.A comparative study of the geological conditions shows that there exixts metallogenic potential in Tangang volcanic basin.

关 键 词：流纹英安岩 锆石U-PB年龄 地球化学 成岩物质来源 火山活动 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学]