安徽省歙县古祝钼(铜)矿床地质特征及成因探讨

歙县古祝钼(铜)矿床,位于江南地块中的江南古隆起带内部的白际岭岛弧带,五里亭—长陔NEE向构造岩浆带内。矿区变质流纹凝灰岩,已变为绢云母石英片岩,形成挤压片理化带,总体走向北东,倾向南东。主体构造为NE向断裂,具有规模大、逆冲和斜向逆冲的特点。成矿母岩为晚侏罗纪世细粒斑状花岗闪长岩,同熔型。矿床以钼矿体为主,次为铜矿体;钼矿石矿物以辉钼矿、黄铁矿为主,铜矿石矿物以黄铜矿、黄铁矿为主。燕山时期,江南陆内造山带形成于壳―幔相互作用等深部过程,随着祁门深大断裂伸展、冲断等转变,岩石圈减薄发生减压熔融,基性岩浆底侵在壳幔边界并使下地壳局部熔融产生中酸性岩浆。岩浆演化分异,钼在岩浆热液中富集,最终演化为含矿热液。随着应力转变,矿质析出,沉淀成矿。

GEOLOGICAL FEATURES AND ORIGIN OF THE GUZHU MOLYBDENUM （COPPER） ORE DEPOSIT, SHE COUNTY, ANHUI PROVINCE

The Guzhu molybdenum （copper） or deposit, She County lies in the Baijiling arc belt inside the Jiangnan Old Uplift Zone of the Jiangnan Massif, in the Wuliting-Changgai NNE-trending tectonomagmatic belt. In the ore field, metamorphic rhyolitic tuff has turned into sericite quartz schist, forming a compressive schistosity belt, generally trending NE and dipping SE. The main structure is a NE fault, big-sealed, thrusting and oblique thrusting. The ore-forming parent rock is late Jurassic fine-grained porphyritic granodiorite of syntectic type. Molybdenum ore body dominates in the deposit compared with copper ore body. Molybdenum-bearing Ores are composed mainly molybdenite and pyrite, and copper-bearing ores of chalcopyrite and pyrite. In the Yanshanian period, the Jiangnan intracontinental orogen formed in the deep process of crust-mantle interaction, with stretching and thrusting of the deep and major Qimen fault, lithospherie thinning led to decompression melting, basic magma underplating occurred at crust-mantle border and caused local melting of lower crust to form intermediate-acid magma. Magmatie evolution and differentiation, and molybdenum enrichment in magmatic hydrothermal solution finally gave rise to ore-bearing solution. With change in stress, mineral substance separated out and deposited to form ores.