闽中山后Pb-Zn矿床地质特征及成因初探

The geological feature of the Shanhou lead-zinc deposit and the preliminary discussion on its origin in the central Fujian Province

闽中山后铅锌矿区位于闽西北遂昌-顺昌隆起带南沿,宁化-南平北东东向断裂带北端。区内地层主要为上元古界马面山群一套中浅变质岩系,总体呈北东东向带状展布,自下而上为龙北溪组(Pt3l)、东岩组(P3d)和大岭组(Pt3dl)。变质程度为绿片岩相-低角闪岩相,原岩为浅海相沉积-火山建造。其中东岩组第二、三段斜长角闪片岩、斜长阳起片岩与透辉石(透闪)岩组合为主要含矿层位。初步认为本矿床属海底火山喷流-沉积-改造型。新元古代海底火山喷流-沉积形成的初始矿源层或矿胚层,经后期热液叠加改造,或再活化,重新定位而形成。

Shanhou lead-zinc deposit is situated on the south margin of the Suichang-Shunchang uplift belt,and on the north of the NEE-trending Ninghua-Nanping fault zone,northwest Fujian province. Neoproterozoic middle-low-grade metamorphosed rocks are exposed and distributed NNE-trending in the district.From bottom to top,it is the Longbeixi Formation,the Dongyan Formation and the Daling Formation.These strata metamorphosed within greenschist facies to low amphibolite facies grade.The protolith of the Mamianshan Group belongs to shallow-sea facies sedimentary-volcanic formation.Among the group,the second and third member of the Dongyan Formation,which consisting of plagioclase hornblende schists,plagioclase anticnolite schists and diopsidite(tremolite),are the chief ore-bearing stratigraphic horizons.The Pb-Zn-Ag deposits hosted in the green schists in the Dongyan Formation of Mamianshan Group is initial source bed formed during marine arc volcanism.Modification and superimposition of metamorphism,tectonism and Yanshanian magmatic hydrothermal solution of initial source bed reformed these deposits,and relocated them.