新疆土屋斑岩铜矿床火山-侵入杂岩体、成矿岩石及其蚀变

摘要

The Tuwu porphyry copper deposit is located in Late Paleozoic Dananhu-Tousuquan island arc in East Tianshan Mountains,Xinjiang.The Lower Carboniferous Qi'eshan Fomration occurs in Tuwu area.The authors recognized a volcanic-plutonic complex at Tuwu that includes two cycles comprising four lithofacies.The first cycle consists of effusive,explosive and pyroclastic phases,whereas the second cycle is characterized by subvolcanic intrusions (diorite porphyry and basalt porphyry).Tuwu volcanic-plutonic complex was intruded by the plagiogranite porphyry which acted as the ore-forming rock.The subvolcanic intrusion is the ore-bearing intrusion and the volcanic rocks are wall rocks.Two ore-forming stages,i.e.,pre-mineralization stage and mainmineralization stage,existed in the Tuwu porphyry Cu deposit.The pre-mineralization stage was formed at the late stage of the volcanic activity which resulted in propylitization.The main-mineralization stage was associated with the emplacement of the plagiogranite porphyry which produced potassic silicate alteration,chloritization-sericitization,and phyllic alteration as well as associated mineralization.The mineralization stages included three sub-stages,i.e.,potassic silicate,chlorite-sericite,and phyllic alteration sub-stages.%土屋斑岩铜矿床位于新疆东天山晚古生代大南湖-头苏泉岛弧中.矿区出露地层为石炭系企鹅山群火山-沉积岩.文章提出矿区出露的火山-沉积岩以及浅成侵入岩为一火山-侵入杂岩体,发育2个旋回4个岩相:第一旋回包括溢流相玄武岩和安山岩、爆发相集块角砾熔岩和爆发-沉积相凝灰岩；第二旋回包括次火山相闪长玢岩和玄武玢岩.斜长花岗斑岩侵入到火山机构断裂系中.矿体赋存于斜长花岗斑岩和闪长玢岩中.斜长花岗斑岩为成矿斑岩,次火山岩相闪长玢岩为容矿岩石,火山岩为围岩.土屋斑岩铜矿床可分为前成矿期和主成矿期.前成矿期形成于火山活动的晚期,发育青磐岩化；主成矿期形成于斜长花岗斑岩侵位时期,发育钾硅酸盐蚀变、绿泥石-绢云母蚀变和黄铁绢英岩化蚀变及与之有关的矿化,形成了土屋斑岩型矿化的主体.矿化阶段包括钾硅酸盐阶段、绿泥石-绢云母阶段和黄铁绢英岩化阶段等.