滇西大坪金矿床成矿流体特征

发布时间：2018-02-24 06:06

  本文关键词： 大坪金矿床 矿化类型套叠 成矿流体特征 成矿物质来源 成矿机制　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：大坪金矿床是我国最重要的新生代金沙江—哀牢山金矿带中的超大型矿床,研究表明该金矿床在主体造山型金矿化之上套叠了浅成低温热液金—多金属矿化,其成矿作用独具特色。为此,论文在对大坪金矿床地质特征的进行系统调研基础之上,通过成矿流体特征和同位素示踪研究,重点剖析了浅成低温热液金—多金属矿化与造山型金矿化叠套成矿的过程和机理,获得如下主要认识:(1)大坪金矿床主体具有造山型金矿的典型地质特征:受控于区域性深大断裂带及其次级断裂带;矿体呈左行雁列式产于高角度断层中;脉状矿化样式发育;以Au矿化为主。(2)南部金河金矿厂矿段显示出浅成低温热液金矿床的地质特征:金矿体发育在缓倾的层间破碎带;角砾状、网脉状和梳状矿化样式发育;大量Ag、Pb和Cu富集;出现冰长石—格子状方解石蚀变矿物组合以及硅化、绢云母化、碳酸盐化和青磐岩化的蚀变分带特征。(3)流体包裹体类型主要分为3类,为H2O两相包裹体、CO2包裹体、CO2-H2O三相包裹体,两种矿化均以CO2-H2O三相包裹体为主。造山型矿化成矿温度为250℃~290℃,浅成低温热液型矿化为250℃~330℃。两种类型矿化流体均为中低盐度,且流体主要成分相似,阳离子以Na+和K+为主,阴离子以Cl-和SO42-为主。造山型成矿流体COCl-、Na+的含量较高;浅成低温热液型成矿流体中K+、SO42-的较高。两种矿化成矿流体表现出相似的特征,表现出成矿流体长期持续的关系。(4)两种矿化类型同位素特征相似:δ18OV-SMOW为10.9‰~14.3‰,δD为-113‰~-40‰;δ34S为2‰~10‰;δ13CV-PDB为-7.6~-2.3‰,显示了两种类型矿化成矿流体的H2O、CO2、S主要来自于壳幔混合作用,并受变质流体的影响。浅成低温热液矿化的Pb同位素特征介于煌斑岩和闪长岩之间,结合煌斑岩富集系数为181.44,而闪长岩富集系数为1.57,代表Pb可能来源于煌斑岩。(5)综合矿床地质、矿床地质特征、成矿流体来源特征和大坪金矿床和区域演化背景,大坪金矿存在造山型矿化和浅成低温热液金—多金属矿化的套叠组合,两种类型矿化形成于从碰撞造山到造山后期伸展活动的长期过程中。
[Abstract]:The Daping gold deposit is one of the most important superlarge deposits in the Cenozoic Jinshajiang-Ailaoshan gold deposit in China. The study shows that the gold deposit overlay the main orogenic type gold deposit with epithermal hydrothermal gold-polymetallic mineralization. Therefore, based on the systematic investigation of the geological characteristics of the Daping gold deposit, the characteristics of ore-forming fluid and isotopic tracer are studied. The process and mechanism of superimposed mineralization of epithermal gold-polymetallic mineralization and orogenic gold mineralization are emphatically analyzed. The main conclusions are as follows: the main body of the Daping gold deposit has typical geological characteristics of orogenic gold deposit: controlled by regional deep fault zone and its secondary fault zone, the orebody occurs in high angle fault as Zuo Xing Yan series, and vein mineralization style develops; Au mineralization is dominant in au mineralization.) the southern Jin He gold mine shows the geological characteristics of the epithermal hydrothermal gold deposits: the gold body develops in the gently inclined interlayer fracture zone, the breccia, reticular vein and comb mineralization patterns develop, and a large amount of Ag Pb and Cu are enriched; The altered mineral assemblage of ice feldspar and lattice calcite and silicification, sericite, carbonization and denudation are mainly classified into three types of fluid inclusions, which are CO _ 2-H _ 2O and CO _ 2-H _ 2O three phase inclusions. The ore-forming temperature of orogenic type is 250 鈩，

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