胶东大庄子金矿地质特征与成因探讨

大庄子金矿是我国首次发现赋存于胶东变质岩中大规模韧-脆性剪切带内的蚀变岩型及石英脉型金矿床.金矿化与绢英岩化、黄铁矿化、硅化和碎裂岩化有关.矿体受韧-脆性剪切带、黄铁绢英岩化、晚元古代晚期角闪岩相变质岩的共同控制.矿石矿物组合以自然金-金属硫化物-架状硅酸盐为主的组合类型.矿床属于在韧-脆性剪切作用下，与含金量较高的下元古界荆山群变质岩的形成、演化有成因联系的蚀变、重熔、交代中温动力热液改造型金矿床.

DISCUSSION ON THE GEOLOGY AND GENESIS OF DAZHUANGZI GOLD DEPOSIT IN EASTERN SHANDONG PROVINCE

The Dazhuangzi gold ore,which depositted gold in the ductile brittle shear zone, is altered rock type and quartz vein type discovered in China for the first time. The mining area is located in Lower Proterozoic Jingshan group on the eastern Yishu fault zone of the northwest upwelling area of the Eastern Shandong land mass,where developed a lot of faulted structures,magmatic activities and metamorphic processes. The types of ore deposits are as follows:1)altered rock type in the fracture zones, occurred in the major fault(F 1)of gently dipping with the compressive torsion stress;and 2) sulphide quartz vein type,occurred in the steep dipping fault(F 2 and F 3) of major fault of the foot wall with tenso shear stress.The dips of the two host structures are mostly opposite,forming λ type structure in plane and section. The gold mineralization is related to sericitization,pyritization,silication and cataclasitization.The orebodies with higher gold grade which is pod like in plane and section is jointly controlled by ductile brittle shear zone,beresitization and metamorphic rock of later Late Proterozoic amphibolite facies.The ore association of mineral is as native gold metal sulfide tectosilicate association. The ore forming process is divided as follows:Ⅱ Hydrothermal mineralization period including 1)gold greyish white quartz fine grained pyrite stage;2)gold milky white quartz middle fine pyrite stage;3)gold greyish white quartz megagrained polymetallic sulphides stage;4)gold grey quartz fine grained polymetallic sulphides stage; and 5)later quartz carbonate stage. Ⅱ.Supergenesis period,including limonite stage. The features of the structural geochemistry are as follows:1)the element association of the mineralized anomaly is quite complete;2)the anomalous distribution of gold and correlative elements is similar to the spreading of ductile brittle shear zone; 3)the contour line distribution of gold and correlative elements is related to the ore control structures; and 4)the anomaly of gold and correlative elements vary in the direction of plane and the element assemblages. The metallogenetic epoch of the deposits is the middle later stage of the Yanshan movement.The ore forming temperature belongs to the lower mesothermal type.The mineralizing fluid comes from the strata,the lower crust and the subcrustal material by lead isotope age.The ore forming solution is remelting and replaced magmatic hydrothermal water. The ore deposit belongs to middle temperature dynamohydrothermal reforming type of gold deposit,which kept the genesis in touch with the formation and evolution of Lower Proterozoic Jingshan group metamorphic rock with higher gold content under the dutile brittle shear action.