川陕甘地区阳山金矿矿床成因及成矿背景

阳山金矿床为中国最大的卡林-类卡林型金矿床,关于其成因有很大的争议,从其成矿背景、岩石化学特征来看,阳山金矿床更具有造山型金矿床的特征。阳山金矿床构造位置上处于大陆内部碰撞造山带,成矿形成于陆陆碰撞造山过程。金矿体严格受断裂构造控制,主要赋存于顺层产出的层间剪切带中;金矿体产于斜长花岗斑岩脉内或者斑岩脉与砂质、粉砂质千枚岩的接触带中,成矿时间与造山活动时间基本相同、与脉岩侵入时间接近,似显成因联系,但成矿流体以大气降水为主,不同于岩浆流体;斑岩脉具有同碰撞花岗岩的特征;金以浸染状为主,但有明金;元素组合以Au、Ag、As、Sb、Hg、Bi为主,具有较大Au/Ag比值。这些特征不同于卡林型金矿床,而与造山型金矿床有相似之处,显示了造山作用与金矿成矿的关系密切。

Deposit genesis and metallogenic background of Yangshan gold deposit

Yangshan gold deposit is the largest Carlin-Carlin-like gold deposit in China. There exist different views in the genesis of the deposit. Considering its metallogenic background and chemical character of the rock, the deposit has the characteristics of orogenic gold deposit. Yangshan deposit located in the collision orogenic belt of inner continent and formed in the continent-continent collision orogenic process. The gold orebodies are strictly controlled by fault structures, mainly hosted in the interlayer shear zone of bedding output. The orebodies host in plagiogranite-porphyry vein or contact zone of porphyry vein and sandy or aleurite phyllite ; the metallogenic time is the same to orogenic time and near to vein rock intruding time, which seems to exist some genetic relationship;as distinguished from the magmatic fluid, the ore-forming fluid is mainly meteoric water; the porphyry veins have the characters of collisional granite; disseminated gold is the main type, there exists some visible gold, as well; the element combination is mainly Au,Ag, As, Sb, Hg and Bi, and the Au/Ag ratio is high. These characteristics are different from the Carlin gold deposit, but similar with orogenic gold deposit. It is indicated that there exist close relationship between orogeny and gold metallogenic course.