福建尤溪梅仙地区马面山群变质岩原岩恢复及其与铅锌成矿的关系

Recovery of Mamian Shan Formation metamorphic rocks and its associations with Pb-Zn mineralization in Meixian,Youxi,Fujian Province

通过变质岩产状、矿物组合及组构特征、矿物间的交代关系、典型矿物空间分布特征、岩石化学、稀土元素化学等方面对原岩恢复进行研究。研究结果表明:丁家山铅锌矿区新元古代马面山群变质岩均为副变质岩,其中石英云母系列变质岩的原岩为泥质粉砂岩和粉砂质泥岩,石榴子石绿帘石透辉石系列变质岩原岩为钙质泥岩、钙质泥质粉砂岩、钙质粉砂质泥岩、泥灰岩等富钙质岩类,而大理岩类的变质原岩为钙镁质沉积岩;丁家山铅锌矿为马面山群龙北溪组上段经加里东期区域变质的富钙质沉积岩与燕山期花岗岩发生接触交代作用而形成的矽卡岩型矿床,矿区广泛存在的石榴子石、透辉石、绿帘石等非金属矿物与磁铁矿、磁黄铁矿、黄铁矿、闪锌矿和方铅矿等金属矿物同为接触交代变质作用在不同阶段的产物。

The occurrence, mineral association and fabric characteristics, metasomatism relationship between minerals, space distribution characteristics of typical mineral, petrochemistry and rare earth chemistry confirmed metamorphic rocks of Mamianshan formation were studied. The results show that the protolith of mica-quartz series metamorphic rocks is peliticsiltstone and silty mudstones; the protolith of garnet-diopside-epidote series metamorphic rocks is calcareous rocks, such as calcilutite, calcareous shale silty sandstone, calcium silty mudstones, maim and so on. The protolith of marble and dolomitic marble are Ca-Mg sedimentary rock. Dingjiashan Pn-Zn ore district is skarn ore deposit caused by the contact metasomatism between Yanshanian granite and the Caledonian regional metamorphismed calcareous rock of Neoproterozoic Mamianshan formation Longbeixi group upper. Both of nonmetallic minerals such as garnet, diopside, epidote and metalliferous minerals like magnetite, pyrrhotite, pyrite, sphalerite and galena are products in different stages of contact metasomatism.