吉林延边金苍矿化带黄铁矿地球化学特征及找矿意义

Prospecting Significance and Geochemical Characteristics of the Pyrites in Jincang Mineralized Belt,Yanbian,Jilin Province

金苍是吉林延边中生代火山岩成矿带内的一个重要矿化区,矿化带内发育黄铁矿化,包括脉状细粒黄铁矿和浸染状粗粒黄铁矿2种类型,对这2种黄铁矿分别进行了主元素和微量元素分析。结果表明:2类黄铁矿主元素含量低于标准黄铁矿,属于硫亏损型,表现出深部、高温的形成环境;黄铁矿微量元素差异较大,为2个成矿期产物;Au及Ag的含量较低,以Cu、Pb、Zn为主,高温Ni相对Co的含量较高,反映其形成温度较高。黄铁矿既存在Co、Ni对Fe的类质同象替代,也存在As、Sb对S的类质同象替代。在与典型热液型金矿床黄铁矿对比后,显示金苍矿化带中黄铁矿不是与火山热液型金成矿有关的成分标型,更多地体现出Cu等金属的成矿特征。黄铁矿的成分地球化学特征不仅能较好地了解矿物的形成环境,而且可以为矿产勘查提供重要的找矿标志。

The Jincang mineralized belt is very important in the Yanbian Mesozoic volcanic area. It is related to gold mineralization in the area. In the mineralized belt, there are two types of pyrite： fine veined pyrite and coarse disseminated pyrite. Main elements and trace elements of the two types of pyrite were analyzed. Both types of pyrite are all lower in sulfur and belong to the sulfur depletion type, indicating a forming environment at deep and high temperature. The contents of trace elements in the two types of pyrite are different and are related to different metallogenic epochs. Contents of Au and Ag in the two types of pyrite were low while those of Cu, Pb, Zn are abnormally high. Among the hightemperature element, content of Ni is higher than that of Co, indicating the pyrite formed at high temperature. In pyrite, not only the isomorphous replacement of Fe by Co, Ni , but also S by As, Sb are common. The pyrite in Jincang mineralized belt are not of the typomorphic characteristics of the gold metallogenesis related to volcanic hydrothermal fluids, but of the typomorphic characteristics of copper metallogenesis when compared with pyrite in the typical gold deposits related to volcanic hydrothermal fluids. The geochemical characteristics of pyrite can indicate the formed environment of the minerals and provide prospecting criterion for mineral exploration.