甘肃成县小沟里金矿床地质特征和控矿因素研究

发布时间：2018-02-04 01:57

本文关键词： 西秦岭小沟里金矿床花岗岩地球化学控矿因素成矿模式　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：西秦岭地区是我国重要的金矿产区之一,该区金矿床类型众多,前人对多数矿床进行综合研究,小沟里金矿床作为西秦岭较独特的石英脉型金矿,但对此研究较薄弱。本文以小沟里金矿床为研究对象,对该矿床地质特征和成矿规律进行详细研究,为西秦岭地区金矿成矿规律的总结提供了原始资料和数据,同时为本区找矿工作指明了方向。本文通过野外实地考察,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,成矿流体包裹体研究,稳定同位素分析,花岗斑岩锆石SHRIMP U-Pb定年测试,成矿年龄研究等工作,对区域矿床地质特征及成矿规律进行了详细研究,取得了以下几点新的认识:1、花岗岩类岩石地球化学测试结果显示:花岗斑岩为酸性、富碱富钠,钙碱性过铝质I型花岗;稀土元素配分型式为轻稀土富集型,重稀土亏损型,配分曲线右倾,为弱负铕异常,与I型花岗岩相似。闪长玢岩为中性岩石,偏酸性、富碱富钠,高钾钙碱性弱过铝质I型花岗岩;稀土元素配分型式为轻稀土富集型,重稀土亏损型,配分曲线平缓右倾,弱负铕异常,与I型花岗岩相似。2、同位素年龄测试结果显示,小沟里花岗斑岩成岩年龄为217.4Ma,闪长玢岩成岩年龄在201-212Ma之间,两种岩体均形成与造山作用后期的构造体制转换阶段。3、通过锆石饱和温度来估算岩浆结晶温度,花岗斑岩的岩浆形成温度比闪长玢岩的岩浆形成温度低,可能是花岗斑岩岩浆源区比闪长玢岩岩浆源区浅。4、小沟里金矿床产于西秦岭西成矿田中部,矿体产于花岗斑岩岩脉、闪长玢岩岩脉上、下盘处及其附近泥盆系地层中,受近东西向的韧性剪切带及与之相配套的张、剪性裂隙的控制。小沟里金矿床单个矿体由脉状、网脉状、树枝状含金石英脉组成,矿体整体走向近东西,沿韧性剪切带呈带状展布。5、小沟里金矿床矿石类型有石英脉型矿石和蚀变岩型矿石。金主要以独立矿物存在,有少量银金矿,主要载金矿物为石英、钠长石、方解石、白云石等碳酸盐矿物。金银矿物主要嵌布与石英粒间、石英与黄铁矿粒间、石英与铁白云石粒间、石英细脉的边部以及由细脉派生的微脉中及其交汇部位。6、矿床H、O、S、Pb稳定同位素地球化学测试显示: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。7、矿床成矿年龄为197.5Ma,略晚于闪长玢岩的成岩年龄;矿石的稀土、微量元素分析结果和元素球粒陨石(原始地幔)标准化配分模式图与闪长玢岩具有相同的稀土、微量元素范围和配分模式。结合矿床地质及矿石结构构造特征,小沟里金矿床的形成与岩浆活动有关,金矿化与闪长玢岩关系尤为密切,因而确定小沟里金矿床为与闪长玢岩岩浆热液有关的岩浆热液型金矿床。
[Abstract]:The West Qinling area is one of the most important gold-producing areas in China. There are many types of gold deposits in this area. Many of the gold deposits have been comprehensively studied. The Xiaogouli gold deposit is a relatively unique quartz vein type gold deposit in the West Qinling Mountains. In this paper, the geological characteristics and metallogenic regularity of the Xiaogouli gold deposit are studied in detail, which provides the original data and data for the summary of the metallogenic regularity of gold deposits in the West Qinling region. This paper makes a detailed study on the field geological characteristics of ore deposits in the study area, and clarifies the characteristics of ore bodies and strata and structures. Spatial relationship of magmatic rock; Through the laboratory light thin section identification, the ore-forming related granite main quantity, the trace element chemical analysis test, the ore-forming fluid inclusion research, the stable isotope analysis. Based on the SHRIMP U-Pb dating test and metallogenic age study of granitic porphyry, the geological characteristics and metallogenic regularity of regional deposits have been studied in detail, and some new understandings have been obtained as follows: 1. The geochemical tests of granitic rocks show that the granitic porphyry is acidic, alkali rich and sodium rich, and calc-alkaline peraluminous type I granitic; The REE distribution pattern is light rare earth enrichment type, heavy rare earth deficiency type, right deviation of partition curve, weak negative europium anomaly, similar to I-type granite. Diorite porphyrite is neutral rock, slightly acidic, rich in alkali and sodium. High potassium calcium alkaline weak peraluminous I type granite; The REE distribution pattern is light rare earth enrichment type, heavy rare earth deficiency type, the partition curve is gentle right dip, weak negative europium anomaly, similar to I-type granite. The isotopic age test results show. The diagenetic age of Xiaogouli granitic porphyry is 217.4 Ma.The diagenetic age of diorite-porphyrite is between 201-212Ma. The magmatic crystallization temperature is estimated by zircon saturation temperature. The magmatic formation temperature of granitic porphyry is lower than that of diorite porphyrite, which may be the shallow .4 of granitic porphyry magmatic source region than that of diorite-porphyrite magma source. The Xiaogouli gold deposit occurs in the central part of the Lingxi metallogenic field in the Western Qin Dynasty, and the orebody occurs in the granitic porphyry vein, diorite porphyrite vein, and Devonian strata at the lower part of the ore deposit and its adjacent Devonian strata. Controlled by near east-west ductile shear zone and associated tensioning and shearing fissures, the sheet orebody of Xiaogouli gold deposit is composed of vein, net vein, dendritic gold-bearing quartz vein, and the whole orebody is close to east and west. Along the ductile shear zone, the ore types of the Xiaogouli gold deposit are quartz vein type ore and altered rock type ore. Albite, calcite, dolomite and other carbonate minerals. Gold and silver minerals are mainly intercalated with quartz grains, quartz and pyrite grains, quartz and iron dolomite grains. At the edge of quartz vein and in the microvein derived from the vein and its intersection. 6, the stable isotopic geochemistry test of Hau Ou Szong Pb deposit shows that the ore-forming fluid has magmatic water and metamorphic water, and the ore-forming fluid is characterized by magmatic water and metamorphic water. The characteristics of multi-source mixed fluid of atmospheric precipitation are dominated by magmatic water; The ore-forming material has the characteristics of deep source. The ore-forming age of the deposit is 197.5Ma. it is a little later than the diagenetic age of diorite-porphyrite. The REE and trace element analysis results of ore and the standardized distribution pattern of elemental chondrites (primitive mantle) have the same REE as diorite-porphyrite. According to the geological and structural characteristics of the deposit, the formation of the Xiaogouli gold deposit is related to magmatic activity, especially to diorite porphyrite. Therefore, the Xiaogouli gold deposit is a magmatic hydrothermal gold deposit related to the magmatic hydrothermal solution of diorite porphyrite.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

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