陕西勉略宁区鱼洞子花岗岩-绿岩地体地质特征及其含金性  

THE GEOLOGICAL CHARACTERISTICS OF THE YUDONGZI GRANITE-GREENSTONE TERRAIN AND ITS GOLD-BEARING PROPERTY IN MIANLUENING AREA SHAANXI

作　　者：秦克令[1] 宋述光[1] 何世平[1] 

机构地区：[1]中国地质科学院西安地质矿产研究所,西安710054

出　　处：《西北地质科学》1992年第1期65-74,共10页Northwest Geoscience

摘　　要：鱼洞子绿岩为笔者在西秦岭南缘地区首次发现的最老含金矿源层。通过阁老岭—鱼洞子地块的详细研究认为,其岩石组合由上壳岩系列的绿岩和花岗片麻岩系列组成。在绿岩建造下部的碎裂混合岩化斜长角闪岩中选获锆石,测得U-Pb年龄为2657±9Ma,因此确定其时代为晚太古代。绿岩建造是本区最主要的含金矿源层。金矿化与构造演化关系密切,大致分为3个阶段:(1)绿岩建造形成阶段。绿岩建造下部的基性火山岩及上部的磁铁石英等主要的金源岩形成。(2)低角闪岩相变质、深部熔融及花岗岩化阶段。伴随低角闪岩相变质及花岗岩化作用,使绿岩建造的金活化并向花岗岩化带的边部及顶部迁移、聚集。(3)褶皱造山和钾长花岗岩形成阶段。主要表现在区内韧性剪切和大型褶皱作用,并伴随有区域绿片岩相的退化变质作用,是本区重要的金的成矿期。此阶段并伴有角闪岩脉侵入,其全岩K-Ar释稀法年龄为2038±30Ma,标志地体克拉通化最终完成。The Yudongzi Group which has been first found by the authors in southern region of the west Qinling mountains, is an oldest gold-bearing source bed It is situated in the eastern end of the Bikou Group bounded by Shaanxi, Gansu, Sichuan, China. It occurs as small nuclear area and is mainly distributed over Gelaoling-Yudongzi region and Lesuhe region to the east of Lue- yang County, and Erliba-Zhaojagou region in Ningiang County, the total areabeig around 100 km^2. The biggest area is the Gelaoling-Yudongzi Block among these regions, Fault contact with the Bikou Group of the middle proterozoic can be seen and locally the Bikou Group unconformably overlies the Yudongzi Group (in Lesuhe region) Through detailed study of the Gelaoling-Yudongzi Block, the authors consider that it ts composed of two series of rocks greenstone formation of supracrustal rocks series and granite-gneiss series. Ziron selected from migmatized cataclastic plagioclase hornblendite in the upper greenstone formation, has been dated by U-Pb isotopic at 2657+9Ma, so the age of the Yudongzi Group is determined to be of the Late Archaean Era. The greenstone formation is main gold-bearing source bed in this area. Gold mineralization closely relates with structure evolution and can be roughly divided into three stages(1)the formative stage of greenstone formation: basic volcanic rock in lower greenstone formation, magnetite quartzite in upper one, etc., main gold-bearing source rocks formed; (2) the stage of lower amphibolite facies metamorphism, melt at bepth and granitization; accompaning lower amphibolite facies metamorphism and granitization, the gold of the greenstone formation was mobilized out, then migrated and accumulated towards the edge and the top of granitizatiort zone; (3)the formative stage of fold-orogeny and kaligranite: the chief display wasductile shea ring and large scale folding in this area, following regional diaphthoresis of greenschist facies and metasomatism of kaligranitization, this stage was an important mineralization per

关 键 词：鱼洞子 花岗岩-绿岩地体 含金性 

分 类 号：P588.121[天文地球—岩石学]