别子型火山成因块状硫化物矿床的地质和地球化学特征

摘要

The earliest Besshi-type VMS deposits formed in Paleoproterozoic, and then widely occurred in Phanerozoic oceanic trench or fore-arc basin.The minerogenetic region has thick sedimentary rock formation under-lain by the volcanic rocks, which is significant for ore-forming material exchanging and metal elements enriching. The strong beresitization occurred in the footwall of Besshi-type deposits while weak chloritization and carbonation occurred in hanging wall.The deposits consists of single orebody or 2～3 connected orebodies.In profile, from bot-tom to top it comprises pillow basalts, massive pyrite ore with coper, blocky banded flint pyrite ore, blocky jasper. The volcanic host rocks of Besshi-type VMS deposits are mostly calc-alkaline with a small number of tholeiitic se-ries, and the geochemical characteristics of trace and rare earth elements are similar to the island arc volcanic rocks on the edge of the active continent.The sulfur in metallogenic fluid is from the mixed source of mantle and seawa-ter, and the metallogenic elements are from mixed source of mantle-crust.%别子型矿床最早形成于古元古代,并在显生宙海沟环境或弧前盆地广泛发育,其成矿区域发育厚层沉积岩地层,覆盖在火山岩之上,对成矿流体物质交换和金属元素富集有重要意义.别子型块状硫化物矿床下盘发育强烈的黄铁绢英岩化,而上盘仅发育微弱的绿泥石化、碳酸盐化.矿床常呈单个矿体产出或2～3个矿体连生,剖面上,由下至上表现为枕状玄武岩→块状含铜黄铁矿矿石→块状、条带状燧石黄铁矿矿石→块状碧玉岩.别子型矿床的火山岩围岩多为钙碱性系列,少量拉斑系列,与活动大陆边缘的岛弧火山岩具有相似的微量和稀土元素地球化学特征.成矿流体中的硫为幔源硫和海水硫的混合来源,成矿元素来源为幔-壳混合源.