青城子矿田石英脉-硅质岩与金银成矿关系讨论

DISCUSSION ON THE RELATIONSHIP OF QUARTZ VEINS AND SILICEOUS ROCKS WITH GOLD AND SILVER METALLOGENESIS

辽东裂谷西段辽河群赋存大型铅锌矿床，近年又发现多处大（ 中）型金银矿床。目前的研究表明，该区金银资源潜力仍然很大。一个值得重视的地质现象是所有金、银矿床都伴随有硅质岩、石英脉的出现。硅质岩受层位控制，呈似层状、扁豆状，基本平行上下岩层，本身亦可构成矿体。辽东裂谷中的金、银、铅、锌矿床与石英脉关系密切，石英脉的规模、分布及特征在很大程度上决定矿床规模。因此，硅质岩、石英脉是地质找矿的直接标志，如在青城子地区，找到了硅质岩就可以发现金矿化。硅质岩主要成分是玉髓，矿物学特征和稀土地球化学特征表明硅质岩是浅海火山喷气的产物，形成于辽河群沉积时沿同生断裂发生的火山喷溢时期，而石英脉则为岩浆期后热液成因，后期热液的叠加更有利于成矿。

In the west section of Liaodong rift, large scale Pb Zn deposits and large or mid dle scale Au Ag deposits have been explored out in Liaohe Group ,with a great potencial of more Au Ag resources proven by the present studies.It should be paid more attention on the geolog ical phenomenon that all these Au Ag deposits accompany with siliceous rocks and quartz veins. In the studied area,the occurrence of siliceous rocks was controlled by stratohorizon with stra toid or lenticular form and basically parallel with sorrounding strata and a siliceous rockbody problebly was an Au Ag orebody ; quartz veins also have close relationship with Au Ag and Pb Zn deposits,their sacle and distribution characteristics decided the scale of deposits. So,ei ther siliceous rocks or quartz veins is a direct sign of geological exploration , for example ,in Qingchengzi area where siliceous rocks have been found with accompanying mineralization . The major mineral composition of siliceous rock is chalcedony . Characteristics of mineragraphy and REE geochemistry indicate that siliceous rocks formed in the effusion period ,while the exhala tion materials of shallow sea volcanoes falling in contemporaneous faults during Liaohe Group was sedimenting ; but the quartz veins were hydrothermal genesis of postmagmatism . Hy drothermal process of postmagthermatism and the postmagmatic superumposing hydrothermal were also favourable to Au Ag metallogenesis.