胶东焦家金矿带招贤金矿床的原位黄铁矿热电性特征及找矿指示意义

In-situ pyrite thermoelectricity and metallogenetic potentiality of Zhaoxian gold deposit in Jiaojia gold belt,Jiaodong Peninsula

胶东金矿集区是中国最大的黄金产地,焦家金矿带是重要的成矿亚带之一,产出了一系列超大型、大型金矿床,资源量占整个胶东地区的1/4,招贤金矿床为焦家带深部的大型金矿床。对招贤金矿床深部成矿潜力的评价可为焦家金矿带乃至胶东地区的金矿床深部找矿预测提供科学依据。文章选取了招贤金矿床3个钻孔6个不同标高的矿石样品,进行了详细的矿物学、成矿元素以及黄铁矿热电性特征研究。通过扫描电镜及半定量成分分析,鉴别了银金矿是主要的金矿物,常以包体的形式赋存于黄铁矿中或其裂隙中。金矿床围岩蚀变分带明显,显示了较强的矿化作用,其矿物共生组合和多阶段的成矿特征与胶东其他超大型金矿床相似。通过Au等成矿元素分析,笔者认为Au及其相关性高的元素具有规律性的垂向变化特征,元素沉淀具有垂向间断性。利用原位黄铁矿热电性测试方法,精准测定了黄铁矿热电性参数,并通过热电系数离散程度、热电性导型、形成温度、延伸指数等计算分析,综合讨论了金矿床成矿潜力,认为招贤金矿床及焦家金成矿带的深部具有较好的找矿前景。

The Jiaodong gold district is an important Au producing area in China.A large number of large gold deposits occur in the Jiaojia gold belt,and its resources occupy a quarter of the whole Jiaodong district.The Zhaoxian gold deposit is a large gold deposit discovered in the outer and deep part of the Jiaojia belt.Evaluating the deep mineralization potential of this gold deposit may provide key insight into the deep exploration and prediction of many gold deposits in the Jiaodong gold district.In this study,ore samples from 6 different elevations in 3 boreholes in the Zhaoxian gold deposit were collected,and detailed mineralogy,ore-forming elements,and thermoelectric characteristics of pyrite were studied.Through SEM and semi-quantitative composition analysis,it is identified that electrum is the main Au minerals,which usually occurs in the form of inclusion in pyrite or its cracks.A large number of hydrothermal accessory minerals are associated with pyrite,and the alteration zoning of the wall rock is obvious,showing strong mineralization.The mineral association and multi-stage ore-forming characteristics are similar to other super large gold deposits in Jiaodong.Through the analysis of ore-forming elements such as Au,it is considered that Au and its highly correlated elements have regular vertical variation characteristics,and the element precipitation has vertical discontinuity.The thermoelectricities of pyrite were accurately determined by in-situ test method,and the ore-forming potential of different orebody was comprehensively discussed by calculating and analyzing the dispersion degree of coefficient,pyrite type,formation temperature and elongation index.The results all indicate that the Zhaoxian gold deposit and the deep of the Jiaojia gold belt have good prospecting potential.