胶东玲珑金矿黄铁矿的化学成分标型特征及其矿床学意义

玲珑金矿作为胶东地区一个规模最大且最典型的石英脉型金矿,历经多年的开采,其保有储量已不足以支持持续生产,深部及边部找矿迫在眉睫。本文基于成因矿物学理论,通过矿物地球化学方法对矿区内的黄铁矿化学成分标型特征研究,结果表明:1)胶东玲珑金矿中黄铁矿为亏硫型,根据其N(S)/N(Fe)值变化趋势,显示其形成温度由成矿前期至成矿期最后到成矿后期逐渐降低。2)胶东玲珑金矿中黄铁矿为富As特征,可作为找矿标志之一;Fe、Cu、Pb三种元素整体上呈迁入状态,随着流体的进一步运移,热液中的HS-等组分逐渐流失,进而导致Au(HS)2-络合物失稳而分解,Fe2+、Fe3+被消耗形成黄铁矿,与此同时Au开始逐渐聚集并沉淀。3)黄铁矿的NiCo图解及As-Co-Ni三角相图显示,绝大部分黄铁矿都属于岩浆热液成因,黄铁矿w(Co)/w(Ni)均值为2.79,说明Au沉淀时的温度为中温。综上并结合区域地质、矿区地质特征及蚀变带特征,认为玲珑金矿床为"岩浆核杂岩"隆起-拆离带中的岩浆期后热液矿床。上述研究成果对玲珑金矿下一步的深部及边部找矿具一定的参考价值。

Typomorphic characteristics of chemical composition of pyrite and its significance in Linglong gold deposit, Jiaodong Peninsula

Linglong gold deposit,as the largest and most typical quartz vein type gold deposit in Jiaodong area,has been exploited for many years,and its reserves are not enough to support sustainable production.It is urgent to find deep and peripheral gold deposits.Based on the theory of genetic mineralogy,the chemical composition typomorphic characteristics of pyrite in the mining area are studied by mineral geochemical method.The results show that:1)pyrite in Linglong gold deposit in Jiaodong is a sulfur deficient type;the overall change trend of the ore-forming temperature shown by the change trend of N(S)/N(Fe)gets decreased gradually from the pre-metallogenic stage to the metallogenic stage-the late metallogenic stage to post metallogenic stage;2)Pyrite’s richness of sulfur can be used as one of the indicators for prospecting;Generally Fe,Cu and Pb are introduced into the fluid system and HS-and other components lost with migration of the fluid and lead to decomposition of Au(HS)2-complex and the consumption of Fe2+,Fe3+to form pyrite;At the same time,Au begins to accumulate and precipitate gradually,and is carried out of the fluid thus the whole metallogenic process is activation-migration-precipitation-enrichment of gold to ore;3)The result of Ni-Co diagrams and As-Co-Ni triangular facies diagrams of pyrite is that most pyrites belong to hydrothermal origin and the average value of w(Co)/w(Ni)=2.79 is characteristic of medium temperature.According to regional geology,geological features of the mining area and characteristics of alteration zone we consider that the deposit is a post-magmatic hydrothermal deposit in the uplift-detachment zone of"magmatic core complex".The above research results have certain guiding significance to further prospecting to depth and periphery of Linglong gold deposit.