鲁西归来庄金矿田碲化物特征与碲金成矿机理研究

Guilaizhuang gold ore field is a very important gold ore field found in western Shandong. The deposits distributed in this ore field occur mainly in the Yanshanian meta-alkalescence volcanic complex and were characterized by the rich tellurides. The Te-Au ore-forming mechanism is often ambiguous and raises wide concerns. This application chooses Guilaizhuang gold ore field as the research object with a focus on an analysis of tellurides characteristics and Te-Au ore-forming mechanism through the following research: (1) Detailed field investigationon the field geological characteristics of volcanic complex and gold ores, including their distribution, zoning and mineral assemblage characteristics; (2) Systematic microscopic observation on the microscopic characteristics of the orebody, mineral assemblages, texture and structure, try to analyze and define the ore-forming stages; (3) A geochemical study of the fluid inclusions. Objective to investigate the composition, temperature, pressure and H, O isotopic features of metallogenic fluid; (4) High-accuracy mineralogical, geochemical and Tof-SIMS micro area analysis with a focus on a research of the elemental geochemistry characteristics, the enrichment regularities of Te-Au and the symbiosis relation between Te-Au; (5) Determining the age of ore-bearing volcanic complex using advanced U-Pb isotopic dating techniques. Comprehensive study on the activization, transportation, concentration of the tellurides so as to set up a Au-Te metallogenic model. This project will help to understand the Te-Au ore-forming mechanism of the Au-Te deposits from Guilaizhuang gold ore field, and provide important information for further prospecting of such deposits.

归来庄金矿田是鲁西地区最重要的的富碲化物型金矿田。金矿体产于燕山早期中-碱性次火山杂岩中，以富含碲化合物为特征。由于其碲金成矿机理尚不明确，而受到广泛关注。本项目拟以归来庄金矿田为研究对象，探索碲金成矿机制。通过详细的野外调研，查清火山杂岩与金矿体的空间分布及矿化蚀变特征；通过矿相学观察，了解各类矿石的矿物组合、矿物世代，并据此厘定成矿阶段；流体包裹体研究，了解成矿流体的成分、温度、压力及H、O同位素组成；高精度矿物学、地球化学和Tof-SIMS微区分析，了解碲化物的元素地球化学特征，富集规律及Te-Au-Ag的共生关系；通过LA-ICP-MS锆石U-Pb测年厘定火山杂岩的形成时代，约束成矿时代；最后综合研究碲化物的来源及其活化、迁移、富集规律，讨论碲金矿床的成矿机制，并建立金-碲矿床成矿模型。本项目有助于深化对富碲化物型金矿床成矿机制的认识，对有关此类矿床的科研和勘查有一定的指示意义。

本项目在详细的野外地质调查的基础上，对归来庄金矿田的主要控矿岩体进行了详细的地球化学、同位素地球化学和年代学研究；系统采集岩体及矿石中石英、方解石、萤石中的包裹体并进行测温，确定归来庄矿床成矿流体为低盐度、低密度流体，矿床形成于中-低压、浅成环境；通过二次飞行时间离子探针、电子探针、扫描电镜、全岩微量稀土分析等多种手段对成矿地质过程中碲元素的地球化学行为进行了系统研究，初步发现中低温、高碲逸度环境下的碲类质同象置换硫而参与成矿是碲元素参与成矿的主要地球化学行为；同时发现了碲金银矿新矿物；在以上基础上，进一步总结了以归来庄金矿田为代表的燕山早期潜火山热液型金矿床的成矿特征和成矿规律；相关研究成果为归来庄金矿田深部找矿实现新突破提供了重要的理论支持。