庐枞盆地早白垩世闪长玢岩锆石U-Pb年龄、地球化学特征及其成矿指示意义  

Zircon U-Pb Dating,Geochemical Characteristics of Early-Cretaceous Diorite-Porphyrites in Luzhong Basin and Their Implications for Mineralization

作　　者：汪晶[1,2] 吴明安[1] 李小东[1] 张舒[1,3] 赵文广[1] 魏国辉[1] 

机构地区：[1]安徽省地质调查院,合肥230001 [2]中国科学与技术大学地球和空间科学学院,合肥230026 [3]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地质学报》2014年第4期547-561,共15页Acta Geologica Sinica

基　　金：国家"深部探测技术与实验研究专项(SinoProbe)"第3项目"深部矿产资源立体探测技术及实验研究"第4课题(SinoProbe-0304);中国地质调查局工作项目<安徽庐枞地区构造;岩浆演化与成矿作用的关系>(工作项目编码1212011120862);深部探测技术与实验研究专项<庐枞地区典型矿床成矿地质条件剖析与火山岩盆地立体模型的研究>(项目编号201011062);地科院地质所合作研究专题(编号DD10-16)共同资助的成果

摘　　要：庐枞盆地是长江中下游成矿带中的重要铁（铜）矿集区，盆地内闪长玢岩与成矿作用关系密切，但目前对庐枞盆地内闪长玢岩地球化学特征及形成时代的认识仍存在争议。本文分析了庐枞盆地内闪长玢岩的主量元素、微量元素、Sr-Nd-Pb同位素组成特征，并利用LA-ICP MS对盆地内泥河铁矿及汪庄铜矿深部的闪长玢岩样品进行了锆石U-Pb 定年。泥河铁矿深部两块闪长玢岩样品中锆石的206 Pb/238 U 加权平均年龄分别为138±1．4Ma及134．5±1．8Ma，而汪庄铜矿三块样品锆石 U-Pb 定年结果分别为133．9±1．9Ma、137．5±1．6Ma 及135．8±2．2Ma。研究结果显示庐枞盆地内闪长质岩浆活动的开始于138 Ma 左右，并可能一直持续到约134Ma。而庐枞盆地内这期较早的岩浆活动可能与周边隆起区（铜陵）约140～145Ma的岩浆活动类似，同时与区内早白垩世成矿作用密切相关，对于在庐枞盆地开展深部找矿具有重要的指示意义。Luzong basin is one of most important units of the iron-copper-polymetallic mineralization belt in the Middle-Lower Reaches of theYangtze-River Area.In Luzong basin,diorite-porphyrite is closely related to ore-forming,but its geochemical characteristics and formation age is still controversial.In this paper, based on the study of major elements and trace elements and Sr-Nd-Pb isotopes,five diorite-porphyrite samples were selected for zircon U-Pb dating.Zircons of two samples from Wangzhuang copper deposit yielded weighted mean 206Pb/238 Uages of 138 ±1. 4Ma and 134. 5 ±1. 8Ma,respectively;while zircons from three samples from Nihe iron deposit yielded weighted mean206Pb/238Uages of 133. 9±1. 9Ma、137. 5 ±1. 6Ma and 135. 8 ± 2. 2Ma respectively.Therefore,there may be a early magmasim inLuzong basin similar to the magmasim with the ages of 140~145 Ma in the peripheral uplift area（Tonglin）.However, this stage of magmasim continued to ca.134Ma in Luzong basin,it is closely related to the metallogenic activity during early Cretaceous and has important significance on deep ore searching.

关 键 词：庐枞盆地 闪长玢岩 地球化学 锆石U-PB定年 

分 类 号：P597.3[天文地球—地球化学] P618.2[天文地球—地质学] P588.12