硒化物、碲化物对金矿床形成机理的指示作用

To various extents, the selenide and telluride occur in many gold deposits all over the world. This project attempts to approach the key problem of “selenide and telluride as the indicator of formation mechanism of gold deposits”, using the ideas and methods from comparative metallogeny. Specifically, this project targets on three orogenic gold deposits including Jialu, Yangzhaiyu and Shanggong, which are all located in the Xiaoqinling-Xiong’er mountain region of the Henan-Shanxi border areas. This project includes the first study of the attitude, the distribution of the selenide and telluride, the mineral intergrowth association between sulfides and oxides, the description of the content and occurrence of selenium and tellurium and their relation with gold in different gold mineralization stages in these three gold deposit, and further study on the source of the ore-forming fluid and the ore-forming material, accurate determination of metallogenic epoch, analysis of the volcanic series of Xiong'er Group, all kinds of migmatite and gneiss of Taihua Group and the metallogenic contribution to regional rock mass and dike at each stage. More research will be carried on the indicator for magmatic rocks with strong mineralization ability and mineralogy and the geochemical tracer study. Finally, based on the metallogenic characteristics comparison and the discrepancy analysis of the physical-chemical condition at different gold mineralization stages among these three gold deposits, this project ultimately aims to discuss the implications of selenide and telluride in these gold deposits in order to reveal the metallogenic process and mechanism, enrich and develop the metallogenic theory of Au - (Ag) - Selenide - telluride deposits.

在世界各地金矿床中都不同程度地存在碲化物和硒化物。本项目运用比较矿床学的思维、方法，围绕“硒化物、碲化物对金矿床形成机理的指示作用”这一关键问题，针对豫陕交界一带的小秦岭-熊耳山地区驾鹿、杨砦峪和上宫造山型金矿床，从研究金矿床中碲化物、硒化物入手，查明矿石中碲化物、硒化物的产出特征、分布规律及其与硫化物和含氧矿物之间的共生组合关系，阐明不同金矿化阶段中碲、硒的含量、赋存形式及其与金赋存状态之间的联系，弄清成矿流体与成矿物质来源，精确测定成矿时代，分析熊耳群火山岩系、太华群各类混合岩与片麻岩及区域内各期次岩体、岩脉对成矿的贡献，开展强成矿能力的岩浆岩指示、矿物学指示与地球化学示踪研究。通过对三个典型金矿床成矿特征对比以及不同金矿化阶段形成物理化学条件差异性分析，探讨硒化物、碲化物对金矿床形成机理的指示作用，揭示金矿床的成矿过程与成矿机制，丰富和发展Au-(Ag)-碲化物-硒化物矿床成矿理论。

在世界各地金矿床中都不同程度地存在碲化物和硒化物。本项目重点对小秦岭地区大湖、金渠、杨砦峪，黑龙江三道湾子，河北东坪等碲化物型金矿床以及四川-甘肃交界一带的拉尔玛、邛莫硒化物型金矿床为研究对象开展研究，探讨碲化物、硒化物对金矿床形成机理的指示作用。取得的主要成果：(1) Au2Te一直作为一个未知矿物或可能的新矿物被多次报道。对三道湾子金矿床在中Au2Te颗粒研究表明，在微米尺度下成分均一的“Au2Te”不是一个新矿物相，而是一个具有纳米级文象结构由自然金和碲金矿组成的混合物。(2) 在东坪金矿区花岗斑岩脉中产出大量“雪球状”石英斑晶，是由富流体岩浆中石英的快速结晶形成，岩浆流动使石英和长石发生定向排列并形成石英斑晶浑圆状外形。岩浆中流体的出溶使钠长石和石英的成核和生长速率发生显著变化，形成石英斑晶中钠长石的核幔结构，显示花岗质岩浆演化对金-碲矿化的制约作用；(3) 在东坪金矿床中首次发现辉钼矿，获得辉钼矿Re-Os模式年龄401.1~376 Ma。由于辉钼矿内部及裂隙中产有自然金颗粒，辉钼矿的形成年龄也代表了金的成矿年龄，表明东坪金矿床与水泉沟正长岩的形成过程有密切成因联系。(4) 在小秦岭大湖金矿床中新发现硫铜铅铋矿、铋铜铅矿和萨硫碲铋铅矿3种含铋硫盐矿物。大湖矿床内存在含铋硫盐及其矿物共生矿物组合显示了矿床形成于岩浆–热液成矿系统。(5) 在小秦岭金矿区的杨砦峪、金渠、大湖等3个金矿床中均发现有白钨矿的产出，并发生了钨的矿化。金矿床中W与Au、Te、Bi关系密切，说明金矿床的成矿作用可能与区域文峪、娘娘山等花岗质岩体有密切的成因联系。 (6) 对Au-Te-Se成矿系统的矿床类型与成矿作用进行了分析，认为岩浆脱气、流体-熔体分离、流体沸腾与混合是碲化物型金矿床的重要成矿机制，而水-岩相互反应、流体沸腾与混合、有机作用是硒化物型金矿床的重要成矿机制。