沱沱河地区扎拉夏各涌铅锌矿成矿时代及其地质意义：钾长花岗斑岩年代学和地球化学特征  

Study on mineralization age and Zhalaxiageyong Pb-Zn deposit by its geological significance of chronology and geochemistry of K-feldspar granite porphyry in Tuotuohe area

作　　者：时超[1,2] 李荣社[1,2] 何世平[1,2] 于浦生[1] 辜平阳[1,2] 张海迪[1,2] 张辉善 

机构地区：[1]中国地质调查局西安地质调查中心、国土资源部岩浆作用成矿与找矿重点实验室,西安710054 [2]中国地质调查局西安地质调查中心、造山带地质研究中心,西安710054

出　　处：《地质科学》2017年第4期1181-1194,共14页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国地质调查局二级项目“秦岭成矿带文康-凤太地区地质矿产调查”（编号：DD20160014）和中国地质调查局工作项目“西南三江成矿带北段地质矿产综合调查”（编号：12120114044801）资助.致谢 本文在撰写过程中得到了潘晓萍教授级高工的热心指导,文中LA-ICP-MS锆石U-Pb年龄测试及地球化学测试得到西安地质调查中心实验测试中心魏小燕、李艳广和汪双双的指导和帮助,同时在野外地质工作中得到了陈世顺高级工程师、王凤林高级工程师、吴玉诗工程师、陈根工程师的大力支持,在此表示衷心的感谢!

摘　　要：三江成矿带北段是我国著名的“三江”铜多金属巨型成矿带的北延部分，构造上属特提斯巨型成矿域的重要组成部分。野外调查期间，对沱沱河矿区的扎拉夏各涌铅锌矿（化）点进行了年代学及岩石地球化学研究。通过高精度LA-ICP-MS 锆石微区原位U-Pb同位素测年，获得与铅锌矿（化）密切相关的钾长花岗斑岩^206Pb/ ^238U 年龄加权平均值为 35.96±0.61 Ma，确定铅锌矿（化）发生在古近纪始新世。地球化学分析表明，钾长花岗斑岩具有高SiO2、Al2O3、K2O， 低 TiO2、Na2O 的特征。在 TAS 岩石分类图解中样品均落入碱性系列的碱性花岗岩区，QAP分类图解中样品均落入碱性长石花岗岩区，K2O-Na2O 图解中样品投入过钾质系列区，A/NK-A/CNK 指数图解中样品投入过铝质区，为过铝质过钾质碱性系列花岗岩。稀土和微量元素地球化学特征显示，该岩体LREE、LILE 和部分HFSE 富集，REE 表现为LREE/HREE 明显分离的分配模式，强不相容大离子亲石元素Sr、K、Rb 、Ba、Th、U 和高场强元素La、 Ce、Nd 等相对富集，从多元素多方法图解中可以看出该斑岩体属于过铝质过钾质碱性—高钾钙碱性系列S 型花岗岩，形成于印度板块与亚洲板块的陆—陆碰撞，青藏高原快速隆升之后的后造山构造阶段的构造环境。Zhalaxiageyong Pb-Zn deposit in Tuotuohe area is located in the northern part of the Sanjiang metallogenic belt in the Tethyan metallogenic domain. Some geochronology and geochemical studied on K-feldspar granite porphyry associated with lead-zinc mineralization. By in-situ LA-ICP-MS zircon dating of the K-feldspar granite porphyry, obtained the ^206 Pb/ ^238U weighted average age of K-feldspar granite porphyry is 35.96 ± 0.61 Ma, and determined the geologic age of Pb-Zn mineralization is the Eocene Epoch. By the results of geochemical analysis, the characteristic of K-feldspar granite porphyry are high SiO2 , Al2O3 ,K2O and low TiO2 , Na2O; All samples fall into alkali granite area of alkaline series by diagram for TAS, All samples fall into alkali feldspar granite area by diagram for QAP; All samples fall into Potassium-rich series area by diagram for K2O-Na2O; All samples fall into Peraluminous area by index diagram for A/NK-A/CNK, and indicates the K-feldspar granite porphyry belongs to the Peraluminous potassic alkaline series granite. By the rare earth and trace elements geochemical characteristics, the K-feldspar granite porphyry are rich of LREE, LILE and partial HFSE, show obvious separate distribution pattern of LREE/HREE, and enrich relatively on Sr, K, Rb, Ba, Th, U elements with strongly incompatibility of large ions and La, Ce, Nd elements with high field strength. By the comprehensive study, the K-feldspar granite porphyry is formed in the continental-continental collision between the India plate and the Asian plate, and the tectonic environment of the post orogenic stage after the rapid uplift of the Qinghai Tibet Plateau.

关 键 词：沱沱河地区 扎拉夏各涌铅锌矿 钾长花岗斑岩 LA—ICP-MS锆石U—Ph定年 构造环境 

分 类 号：P588.12[天文地球—岩石学] P597[天文地球—地质学]