钦杭成矿带西段古龙花岗岩株群岩石学、地球化学及年代学  

Petrography,Geochemistry and Chronology of Gulong Granite Stock Group in West Segment of Qinzhou-Hangcheng Metallogenic Belt

作　　者：许华[1] 黄炳诚[1] 倪战旭[1] 钟辉运[1] 黄英[1] 李乾[1] 

机构地区：[1]广西区域地质调查研究院,广西桂林541003

出　　处：《华南地质与矿产》2012年第4期331-339,共9页Geology and Mineral Resources of South China

基　　金：中国地质调查局地质矿产调查评价专项(编号:1212011120815)

摘　　要：古龙花岗岩株群包括大村、古龙、思泰、社山、上木水、大坡等侵入体,岩性主要为石英闪长岩-英云闪长岩-花岗闪长岩-二长花岗岩组合,岩石普遍含角闪石。岩石化学系列属于钙碱性系列-高钾钙碱性系列,主量元素具高CaO低K2O的特征。稀土总量低,轻稀土富集,弱Eu亏损。微量元素Nb、Ta、Sr、P、Ti强烈亏损,Th、U、Zr、Hf相对富集。对古龙岩体进行了高精度的LA-ICP-MS锆石U-Pb定年,获得石英闪长岩等时线年龄为445.9±1.2Ma(MSWD=0.035)。研究认为古龙花岗岩株群形成于早志留世,属于加里东期I型花岗岩,形成于华南加里东期造山带俯冲-碰撞挤压构造背景,岩浆物质来源主要为俯冲带幔源岩浆并混入了部分壳源物质。Gulong granite stock group is composed of the intrusive bodies in Dacun, Gulong, Sitai~ Shangmushui, Dapo, etc., and is mainly assembly of quartz diorite- tonalite- granodiorite- admellite, and commonly contain hornblende. Those rocks are belong to calc-alkaline series and high-K talc alkaline series, with higer CaO content. The rocks are characterized by low REE contents, consistently show LREE-riched patterns, weakly Eu depletion, depletion of Nb, Ta, Sr, P, Ti, and relatively rich in Th, U, Zr, Hi＇. Zircon LA-ICP-MS U-Pb dating of quartz diorite yielded the isochron age of 445.9 _＋ 1.2 Ma（MSWD=0.035 ） in Gulong granites, and indicated that Gulong granites stock group were formed in Early Silurian, and is part of Caledonian I-type granites which were formed in Caledonian orogenic belt of South China subduction-collision squeezing tectonic setting. The source for Gulong granite mainly are the mantle-derived magma from subduction zones, partly mixed with the crustal material when magma intrusion.

关 键 词：岩石地球化学 LA-ICP-MS锆石U-PB年龄 古龙花岗岩株群 钦杭成矿带西段 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]