应用电子探针技术研究%山东金青顶金矿床碲化物特征

Application of Electron Microprobe to Study the Features of Tellurides in the Jinqingding Gold Deposit,Shandong Province

对含碲金矿中碲化物物相组成和元素赋存特征开展系统的研究,有助于对此类金矿矿床成因的理解和找矿勘查工作。山东金青顶金矿床伴生的碲化物由于碲化物颗粒较小,不易被发现,以往的研究缺乏对碲化物元素分布的精细刻画。本文通过电子探针背散射图像、波谱分析、能谱分析结合面扫描技术对金青顶金矿床碲化物进行了分析,研究碲化物的种类、共生关系、化学成分以及元素分布特征等。结果表明:碲金银矿与碲银矿密切共生,常形成连生体,Au、Ag在连生体中不均匀分布,面扫描图局部可见碲金矿亮斑;Te总是优先和Ag结合,生成碲银矿,随着Ag的消耗碲金银矿开始出现,Ag被耗尽后Te与Au生成碲金矿,成矿后期热液中多余的金与碲金银矿或碲银矿反应生成非常规碲化物(如本文发现的Ag2.95Au1.83Te),当Te消耗完后生成自然金;金银矿物的生长顺序是碲银矿—碲金银矿—碲金矿—自然金。本研究为含碲金矿的综合利用提供了技术支持。

A systematic study of the phase composition and element occurrence characteristics of tellurides in tellurium-bearing gold deposits will be helpful for the genesis understanding of gold deposits of this type and for prospecting exploration. Tellurides in the Jinqingding gold deposit are too small and are difficult to identify.Previous research lacked the detailed studies of the element distribution characteristics of tellurides. In this study,the types,symbiotic relationship,chemical composition and element distribution characteristics of tellurides in the deposit were analyzed by electron probe using BSE,WDS,EDS and mapping modes. Results show that petzite is closely associated with hessite and intergrowths of these two minerals are common. Au and Ag are unevenly distributed in the intergrowths,and calaverite shows as a bright spot in the scanning map. Tellurium is always likely to combine with Ag to form hessite. With the consumption of Ag,petzite began to appear and Te combined with Au to form calaverite after exhausting Ag in magmatic hydrothermal fluids. The superfluous Au in the hydrothermal fluids at the later stage of mineralization reacted with hessite or petzit to produce unconventional tellurides,finally forming a native gold. The growth of gold-silver minerals follows the sequence,hessite,petzite,calaverite,and Au from early to late. This study provides technical support for the comprehensive utilization of tellurium-bearing gold deposits.