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

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。

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

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. 238 By in-situ LA-ICP-MS zircon dating of the K-feldspar granite porphyry, obtained the 206 Pb/ U 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.