广西桂西北地区花岗岩岩体地球化学特征对比及其地质意义  

Comparison of geochemical characteristics of granite rocks massin Northwest Guangxi and its geological implication

作　　者：王展宇 陈远荣[1] 刘奕志[1] WANG Zhanyu;CHEN Yuanrong;LIU Yizhi(College of Earth Sciences,Guilin University of Technology,Guilin 541006,Guangxi,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006

出　　处：《矿产与地质》2020年第4期752-760,共9页Mineral Resources and Geology

基　　金：国家科技支撑项目(2014BAB05B00);有色及贵金属隐伏矿床勘查教育部工程中心项目(2015GCZX006);广西研究生教育创新计划项目(YCBZ2019055)共同资助。

摘　　要：广西桂西北地区位于华夏地块以西、扬子地块以南的江南构造带西南缘,区内花岗岩发育,典型岩体有摩天岭岩体和元宝山岩体,形成于晋宁晚期(820~825 Ma)。从主量元素、微量元素和烃类组分含量等角度,研究其形成的地质背景、演化关系和成矿潜力,结果表明:区内岩体具有富钾、铁,低钠,贫钙镁,A/CNK>1.1,为强过铝质的特征,均属于S型花岗岩;两个岩体的微量元素组合相似度高且稀土元素含量均低于世界的平均水平,LREE富集,(La/Yb)N、(Gd/Yb)N值和δEu值从早阶段至晚阶段都明显降低;摩天岭花岗岩与元宝山花岗岩烃类组分的曲线结构相似,但是摩天岭花岗岩总烃含量、烃类组分各个分量(甲烷至丙烯)均高于元宝山花岗岩,显示了摩天岭岩体与成矿更为密切;摩天岭岩体成矿物质来源较浅,与其周围区域可形成规模较大的W、Sn、Pb、Bi等矿床;而元宝山岩体成矿物质来源较深,与其周围区域难以形成矿化体或较大矿化体。The northwest Guangxi is located in the southwest margin of Jiangnan tectonic belt to the west of Cathaysia Block and south of Yangtze block.Granites are well developed in the area.The typical rock bodies are Motianling rock mass and Yuanbaoshan rock body,which were formed in the late Jinning period(820-825 Ma).The geological background,evolution relationship and metallogenic potential of the granites are studied from the aspects of major elements,trace elements and hydrocarbon components.The results show that the rocks in the area are rich in potassium,iron,low in sodium,poor in calcium and magnesium,and A/CNK>1.1,which are strongly peraluminous and belong to S-type granites.The trace element association similarity of the two rock bodies is high,and the REE content is lower than that of the world.(LA/Yb)N,(GD/Yb)N andδEU values decreased significantly from the early stage to the late stage.The curve structures of hydrocarbon components of Motianling granite and Yuanbaoshan granite are similar,but the total hydrocarbon content and each component of hydrocarbon components(methane to propylene)of Motianling granite are higher than those of Yuanbaoshan granite,indicating that the Motianling granite is more closely related to mineralization.The Motianling pluton has a shallow source of ore-forming materials,and large-scale W,Sn,Pb,Bi deposits can be formed with its surrounding areas,while Yuanbaoshan pluton,with a deep source of ore-forming materials,is difficult to form mineralized bodies or large-scale mineralized bodies in its surrounding areas.

关 键 词：地球化学特征 烃类组分 花岗岩 摩天岭 元宝山 桂西北 

分 类 号：P588.121[天文地球—岩石学]