安徽省池州市马石铜矿地质特征及控矿因素

GEOLOGICAL CHARACTERISTICS AND ORE-CONTROLLING FACTORS OF THE MASHI COPPER DEPOSIT IN CHIZHOU CITY, ANHUI PROVINCE

马石铜矿床位于安庆-贵池矿集区内,是一个几经上下、近年找矿有较大突破的中型斑岩矿床。矿体赋存于花岗闪长斑岩体顶部及侵入接触带附近。矿床主矿体2个,编号为Ⅲ、Ⅳ。矿体呈不规则的透镜状产出,其形态、产状受岩体及接触带构造控制,走向北东,倾向北西,倾角9°～33°。矿石矿物主要为黄铜矿,其次为黄铁矿、辉钼矿、黝铜矿、白铁矿、闪锌矿、方铅矿、胶状黄铁矿等。脉石矿物主要有中—更长石、钾长石、石英等。矿石结构主要有自形—半自形晶、他形晶、乳滴状、压碎—碎斑、交代溶融结构等,矿石构造主要有脉状—网脉状、浸染状、角砾状、胶结、次块状构造等。矿体围岩蚀变有青磐岩化、泥化带、石英—绢云母化、钾质蚀变带,铜矿化与泥化带、石英—绢云母化蚀变带关系最为密切,表现为矿体中石英脉、石膏脉、钾化等很发育。矿床成因类型是斑岩型铜矿床,主要控矿因素是构造、岩浆岩。

Located in the Anqing-Guichi ore deposit cluster,the Mashi copper deposit is a medium-size porphyry deposit that has experienced ups and downs in the long past and made great breakthroughs in recent years.The ore bodies occur at the top of the granodiorite porphyry and near the intrusive contact zone.Two main ore bodies are numbered III and IV,which are in irregularly lenticular form.Their forms,occurrences are controlled by rock mass and contact zone structure,trending NE,dipping9°~33°to northwest.The ore minerals are mainly chalcopyrite,followed by pyrite,molybdenite tetrazolite,marcasite,sphalerite,galena,colloidal pyrite,etc.Gangue minerals mainly include andesine-oligoclase,potassium feldspar,quartz,etc.The ore is texturally mainly automorphic-semiautomorphic,allotriomorphic,emulsion droplet-like,crushing-porphyroclastic,metasomatic melt,etc.,and structurally vein-stockwork-like,disseminated,brecciated,cemented,sub-massive an so on.Wall rock alteration includes greenpanitization,argillation zone,quartz-sericitization and potassium alteration zone,and the copper mineralization is closely related to the argillation zone and the quartz-sericization alteration zone,showing that quartz vein,gypsum vein and potassium alteration are very developed in ore bodies.It is genetically porphyry copper deposit and the main ore-controlling factors are structures and magmatic rocks.