江南造山带南段印支期崇阳坪花岗岩岩石成因、构造环境与找矿前景分析  

Petrogenesis,tectonic setting and prospecting perspective of the Indosinian Chongyangping granite in the Zhaixishan tungsten orefield,southern Jiangnan Orogen

作　　者：彭思才 吕书君 李永德 王义天[2] PENG Sicai;LYU Shujun;LI Yongde;WANG Yitian(Natural Resources Investigation Institute of Hunan Province,Huaihua 418000,Hunan,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]湖南省自然资源调查所,湖南怀化418000 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《矿产勘查》2023年第10期1923-1936,共14页Mineral Exploration

基　　金：湖南省财政项目“湖南省绥宁县寨溪山矿区钨矿普查”(20140323)资助。

摘　　要：寨溪山钨矿床崇阳坪花岗岩体位于江南造山带南段,岩体主要由细粒黑云母二长花岗岩、中细粒黑云母二长花岗岩、中粒斑状黑云母二长花岗岩组成,钨矿化主要产于中细粒(斑状)黑云母花岗岩中。花岗岩具有较高含量的黑云母,A/CNK≤1.1,属准铝质—弱过铝质花岗岩,显示较强的Rb、Ce、Pb、Zr正异常和Ba、Nb、Sr、P、Ti负异常,岩石富集轻稀土,LREE/HREE为4.59~9.63,呈右倾型。结合岩石矿物学及元素地球化学特征,推断花岗岩为地壳变质杂砂岩和基性岩的部分熔融形成的I型花岗岩。可能形成于晚三叠世造山峰期之后的挤压减弱、应力松弛的后碰撞阶段,地壳岩石由于受到热应力松弛作用的影响,加厚地壳岩石发生部分熔融,岩浆上侵而成。江南造山带印支期花岗岩在时间、空间上与周缘的钨矿床基本一致,指示其具有良好的成矿潜力,寨溪山钨矿床从地表浅部向下,细脉变粗、矿体延伸稳定,局部出现石英大脉型钨矿体,深部找矿潜力良好。The Chongyangping granite is an important ore-forming rock unit in the Zhaixishan tungsten orefield in the southern part of the Jiangnan Orogen(South China),and its comprises three main lithofacies:fine grained biotite monzogranite,medium-fine-grained biotite monzogranite and medium-grained porphyry biotite monzogranite,and tungsten mineralization is genetically related to medium-grained porphyry biotite granite.The granite is remarkably enriched in Rb,Ce,Pb and Zr,slightly enriched in LREE(LREE/HREE=4.59-9.63),strongly depleted in Ba,Nb,Sr,P and Ti,and is metaluminous-peraluminous(A/CNK≤1.1)high-K calcalkaline.Combined with the mineralogy and geochemical characteristics of the medium-grained porphyry biotite granite,we inferred that the causative magma was formed from partial melting of the meta-greywacke and metabasite under late Triassic post-orogenic extension setting.The geological and geochemical characteristics of the Indosinian Chongyangping granite is similar to those of contemporaneous tungsten mineralized granite in the southern part of Jiangnan Orogen,suggesting that the Chongyangping granite has good ore-forming potential.The thickness of W-bearing quartz veins in the Zhaixishan tungsten deposit gradually thickens from the surface to the depth,and large vein type orebodies appear in local sections,indicating that the deep area has better prospecting potential.

关 键 词：印支期花岗岩 岩石成因 构造环境 找矿前景 江南造山带 

分 类 号：P581[天文地球—岩石学]