【作者】 魏均启；

【导师】 刘云华；

【作者基本信息】 长安大学 ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 西秦岭地区是我国重要的金矿产区之一,该区矿产空间分布具有分段成群成带展布的特点,李子园地区碎石子金矿床即产于西秦岭地区北成矿带。本文以天水李子园地区碎石子金矿床为研究对象,通过野外实地考察,对研究区矿床野外地质特征进行了详细的研究,厘清了矿体的产出特征以及与地层、构造、岩浆岩的空间关系；通过室内光薄片鉴定,成矿有关花岗岩主量、微量元素化学分析测试,成矿流体包裹体测定,稳定同位素分析,锆石SHRIMP U-Pb定年测试,矿化蚀变绢云母K-Ar定年测试等工作,对区域矿床地质特征及成矿规律进行了详细研究,取得了以下认识：1、李子园地区金矿床产于西秦岭商丹缝合带南侧的次级断裂构造带中,分布于天子山二长花岗岩与宽沟花岗斑岩、闪长玢岩附近,矿床总体受北西向韧-脆性断裂构造的控制,其中碎石子金矿床产于天子山岩体内部,与闪长玢岩关系密切。2、同位素年龄测试结果显示,天子山二长花岗岩成岩年龄为236.1Ma,花岗斑岩、碎石子闪长玢岩成岩年龄分别为213.9Ma和212.2Ma,天子山岩体形成于秦岭造山带主碰撞期,宽沟花岗斑岩、碎石子闪长玢岩形成于造山作用后期的构造体制转换阶段。3、碎石子金矿床矿体主要赋存于闪长玢岩及闪长玢岩附近的断裂破碎带中,受断裂破碎带和闪长玢岩脉的控制,矿石类型有闪长玢岩型矿石和破碎带蚀变岩型矿石。4、矿床的载金矿物主要为黄铁矿,其次为黄铜矿、方铅矿；金银矿物多呈细粒状和细脉状充填在黄铁矿的裂隙和间隙中,或嵌布在黄铁矿与其它硫化物矿物或脉石矿物的界面处,以单体金和连生金为主。5、矿床成矿温度100～300℃,盐度为2.0～10.8wt%(NaCl eqv),为中低温中低盐度型金矿床,成矿流体具有岩浆水、变质水、大气降水多源混合流体的特点,以岩浆水为主；成矿物质具有深源的特点。6、蚀变闪长玢岩中绢云母K-Ar同位素年龄测试结果为206Ma,代表了金矿的形成年龄,结合闪长玢岩成岩年龄为212.2Ma,表明金矿成矿作用与闪长玢岩关系密切,为与闪长玢岩有关的斑岩型金矿床,形成于秦岭造山作用后期的伸展阶段。7、综合以上研究,初步探讨了李子园地区碎石子斑岩型金矿床的成矿模式,为本区的地质研究及找矿工作开展提供了一定的参考依据。更多还原

【Abstract】 Western Qinling is one of the important gold deposit areas of China.The spatial distribution of mineral resources in the area has the characteristics of distribution into groups and belts segmentally. And SuiShiZi gold deposit in LiZiYuan was found in north metallogenic belt of western Qinling. In this paper, the author takes SuiShiZi gold deposit in LiZiYuan,TianShui as the research object. During the field investigation, geological surveies in mining area have been operated in detial, and the ore body to deliver the characteristic as well as with the stratum, the structure, the magmatic rock spatial relations have been Studied. At the same time,the auther took the thin section under the light microscope, chemical analyses and tests of major elements and trace elements, determination of fluid inclusions, stable isotope analysis, zircon SHRIMP U-Pb dating, K-Ar dating of mineralized altered sericite, etc indoors. The regional geological features and metallogenic regularities were studied in detail, preliminary cognitions have been acquired as follows:1.LiZiYuan gold deposit which occurs in secondary falt structural belt in the south of Western Qinling Shang-Dan suture zone, is located near the Tianzishan monzonitic granite、Kuangou granite porphyry and diorite porphyrite, and controlled by north-west uolcanic fractured zones,Suishizi gold deposit,located in the intel of Tianzishan rock mass,is associated with diorite porphyrite.2.Test on isotope age showed that the diagenetic age of Tianzishan monzonitic granite is 236.1 Ma, while that of granite porphyry、Suishizi diorite porphyrite are respectively 212.2 Ma and 213.9 Ma. Tianzishan rock mass was formed during the collision period of Qinling orogenic belt, while Kuangou porphyry granite、Suishizi diorite porphyrite were formed during regime switching in late orogenesis.3.Suishizi gold deposits mainly occur in the diorite porphyrite and breakage crushed belt near the diorite porphyrite,and are controlled by breakage crushed belt and diorite porphyrite dike, the mineral types are diorite porphyrite mineral and crushed zone alteration mineral.4.The gold-carrying minerals of the deposit are pyrite, with the contributions of chalcopyrite and galena. Gold and silver-bearing minerals, which are mainly disseminated and vein-disseminated,mostly show fine granulars and fine veins, filling in the cracks and gaps of pyrite, or disseminating in the interface between pyrite and other sulfide minerals or gangue minerals.5.The deposit is a middle-low temperature(metallogenic temperature is 100～300℃)and salinity(2.0 to 10.8 wt% for NaCl eqv).Ore-forming fluids are charactered by a mixed resource of magma water(mainly), metamorphic water and air water.Mineralizing materials have the characteristics of deep source.6. Combining the diagenetic age of diorite porphyrite is 212.2 Ma,the K-Ar isotopic age of sericite in altered diorite porphyrite is 206 Ma, representing the forming age of the gold deposit, indicates the close relationship between mineralization of gold and diorite porphyrite.This deposit isthe metallogenic model of gold deposit which is related with diorite porphyrite,and it formed during tne spread stage of the later of Qinling orogenesis.7.Based on the above studies, the metallogenic model of SuiShiZi gold deposit in LiZiYuan has been preliminary established,providing certain references for the geological research and the development of the ore-prospecting work in the region.更多还原