福建宁化溪源锌矿床的地质特征及其成因探讨

位于闽西北的溪源锌矿床产在中变质的中-上元古界黄潭组中段第二层和第四层中，呈层状，沿走向、倾向变化较稳定。矿层与围岩存在着过渡的关系。矿区内中-上元古界黄潭组至少经历了两期叠加的褶皱构造变形，早期为紧闭等斜向形，构成矿区的主体构造，总体为近东西向，向南西倾伏；晚期为直立褶皱，褶皱轴主要为北东—北北西向。矿区的断裂和岩脉均形成于成矿后，对含矿层位起破坏作用。矿床成因类型为沉积一变质型，属于同生型层控矿床。中-上元古界黄潭组中段含矿层位的透辉石岩等钙镁质岩是锌矿矿源层。区域变质产生的热液交代矿源层及其围岩，造成矿质分配、富集成矿。后期岩浆热液的改造叠加了铍矿化，并导致锌矿的再次富集，但仅限于局部，意义不大。

On the Geologic Characteristics and Genesis of the Xiyuan Zinc Deposit in Ninghua County, Fujian Province

The Xiyuan Zinc Deposit, situated at the northwestern part of Fujian Province, is discovered in the secondary layer and fourth layer of the intermediate section of mesometamorphic strata Middle-Upper Proterozoic Huangtan Formation with an occurrence in beds and a stable variance in trend and incline. There exists a transitive relation between the ore beds and country rocks. In the surveyed area the strata of Middle-Upper Proterozoic Huangtan Formation went through two more stages of superposed folding tectonic distortion. The early stage of superposed folding tectonic distortion make a shape of tight isoclinal synforms with the near east-west trend and the southeastern plunge, which make of the main geological structures of the mining area. The late stage of superposed folding structures are upright folds with the northeastern and north-northwestern fold axial trend. The fractures and veins in the minefield came into existence after the ore-forming process, which take a destructive effect on ore-bearing layers. The genetic type of the Deposit belongs to the sedimentary-metamorphism type and it is a syngenetic pattern of the stratabound deposit. The calc-magnesian rocks such as diopsidite, distributed in the intermediate section of Middle-Upper Proterozoic Huangtan Formation, are the source bed of the zinc ores. The regional metamorphism brings forth the replacement of source beds and country rocks from the hydrothermal fluids and results in the partitioning and enrichment of mineral matters so as to form the ore deposit. The late stage of magmatic hydrothermal alteration and superposition forms the mineralization of beryllium ores and brings about re-concentration of zinc ores in the local area, which is of no consequence.