VAMSD矿床系列最基性端员——青海省德尔尼大型铜钴矿床的地质特征和成因类型

THE EXTREMELY BASIC MEMBER OF VAMSD DEPOSIT SERIES——THE DEERNI LARGE COPPER-COBALT DEPOSIT OF QINGHAI PROVINCE:ITS GEOLOGICAL CHARACTERISTICS AND GENETIC TYPE

在调查分析德尔尼Ｃｕ－Ｃｏ（－Ｚｎ）矿床地质特征的基础上，结合矿床剖面，针对矿区容矿蛇纹岩类进行了系统的岩矿鉴定和地球化学研究，确定矿区广泛发育的各类蛇纹岩基原岩主要为超基性角砾集块岩、凝灰岩等火山岩类。矿化产于橄榄质火山角砾岩及其上覆富镁质碳酸盐岩和火山沉积岩之间（中）。对该矿床岩浆熔离论和热液论的成困提出不同见解。

The Deerni large copper cobalt( zinc) deposit exhibits unique geological features,and there exists much controversy over its genesis. Based on previous researches and a detailed field investigation and study on the host volcanic rocks,orebodies,ores,isotope and trace element geochemistry in correlation with typical ore deposits,this paper classified it as belonging to VAMSD type(submarine volcanics hosted massive sulfide deposit),thus denying such previous genetic views as magmatic liquation and hydrothermalism. In combination with the geological section of the ore deposit,the authors made systematic rock and mineral identification and geochemical study on host serpentinites in the ore district and ascertained that protoliths of various sorts of serpentinites in the ore district are mainly such volcanic rocks as ultrabasic volcanic rocks,breccia agglomerate and tuff,associated with pyroclastic sedimentary rocks like serpentine magnesitite. It is held that mineralization occurs within or between ultrabasic volcanic breccia and its overlying magnesium rich carbonate rocks and volcanic sedimentary rocks,with ore forming materials derived mainly from ultrabasic rocks and partly from basic rocks. It is also pointed out that ore bearing volcanics assemblage consists of basic ultrabasic rocks rich in MgO and deficient in CaO,with high MgO/<FeO>ratio. Moreover,basic rocks are characterized by rich Na 2O and poor K 2O,whereas ultrabasic rocks correspond chemically to volcanic peridotite(komatiitoid). In VAMSD deposit series,this volcanics assemblage is the extremely basic assemblage of ore bearing rock series,and ore deposits produced by this assemblage is distinctly characterized by copper cobalt metallic association. Hence,the authors definitely classified the Deerni type copper cobalt (zinc)deposit as the extremely basic member of the VAMSD deposit series and pointed out its significance in the geological theoretical study and exploration of VAMSD deposits.