闽中梅仙铅锌矿田赋矿变质岩系对比及深部找矿前景

Comparison of ore-bearing metamorphic rock series in the Meixian Pb-Zn ore field in Central Fujian Province and its deep prospecting potential

梅仙铅锌矿田形成于闽中大陆裂谷环境中,铅锌矿体主要赋存于中新元古代马面山群东岩组绿片岩相的变质岩系内,层位和岩性控制特征显著。在充分研究前人成果的基础上,通过对马面山群变质岩层序及地球化学特征的分析研究,对梅仙地区铅锌矿赋矿变质岩系地层进行了划分对比,认为梅仙矿田中新元古代马面山群变质岩系自老至新为龙北溪组、东岩组。龙北溪组为下伏于东岩组的一套巨厚的海相硅质、钙镁质、半黏土质、泥砂质沉积变质岩系,间隙有小规模的基性—超基性岩浆喷发。东岩组为一套具多个旋回的"双峰式"(基性—中酸性)火山喷发与泥钙质沉积的喷发—沉积序列。研究认为,丁家山矿区与峰岩矿区的赋矿变质岩系并非同一层位,而是下伏于其下的含矿岩层,峰岩矿区深部具备寻找丁家山式铅锌矿床的前景。

The Meixian Pb-Zn ore field is located in the central Fujian continental rift,and the Pb-Zn orebodies are mainly hosted in greenschist facies metamorphic rocks of Meso- and Neoproterozoic Mamianshan Group Dongyan Formation,obviously controlled by strata and lithology. Based on previous work,this study analyzed the Mamianshan Group metamorphic sequence and its geochemical characteristics,and further divided and compared the Pb-Zn-hosting metamorphic rock series. It is inferred that the Meso-Neoproterzoic Mamianshan Group metamorphic rocks can be divided into the Longbeixi Formation and Dongyan Formation from old to young. The Longbeixi Formation underlying the Dongyan Formation is a mega-thick marine siliceous,Ca-Mg-bearing,semi-clayey and argillaceousarenaceous sedimentary metamorphic rocks series,with occasionally small-scale basic-ultrabasic magmatic eruption. It is suggested that the ore-hosting metamorphic series of the Dingjiashan mining area is not the same layer to that of the Fengyan mining area,but the underlying layer. Therefore,the Fengyan mining area has a great potential for prospecting Dingjiashan type Pb-Zn deposits at depth.