新疆东天山图拉尔根大型铜镍矿床硫化物珠滴构造的特征及其对通道式成矿的指示  

Characteristics of multiphase sulfide droplets and their implications for conduit-style mineralization of Tulargen Cu-Ni deposit,eastern Tianshan,Xinjiang

作　　者：刘平平[1,2,3] 秦克章[1] 苏尚国[2] 三金柱[1] 唐冬梅[1,3] 苏本勋[1,3] 孙赫[1,3] 肖庆华[1,3] 

机构地区：[1]中国科学院矿产资源研究重点实验室中国科学院地质与地球物理研究所,北京100029 [2]中国地质大学(北京),北京100083 [3]中国科学院研究生院,北京100049

出　　处：《岩石学报》2010年第2期523-532,共10页Acta Petrologica Sinica

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-YW-107);国家"十一五"科技支撑计划新疆305项目东天山铜镍矿专题(2006BAB07B03-01)联合资助

摘　　要：东天山图拉尔根岩浆铜镍硫化物矿床中产出一种不常见的硫化物珠滴状构造。这些硫化物珠滴粒度在5～20mm左右,是由磁黄铁矿、镍黄铁矿、黄铜矿等硫化物矿物组成的斑杂状硫化物集合体。野外观察发现硫化物珠滴具有各种几何形态,产出在稀疏浸染状硫化物和无矿化的辉石岩之间的部位。对图拉尔根杂岩体中发育的24个硫化物珠滴的统计结果显示,平缓厚层状矿化部位的硫化物珠滴呈水平方向拉长,陡倾薄层状矿化部位的硫化物珠滴呈陡倾拉长,珠滴的拉长方向和矿体的延伸方向一致。这表明在含矿母岩浆上升就位到中上地壳的过程中,硫化物珠滴受到熔浆流动的控制,因而其形态可以很好地指示通道式成矿硫化物熔体运动的方向。硫化物珠滴的矿相学和电子探针数据表明其具有向地性特征,即磁黄铁矿和镍黄铁矿先结晶,沉淀在下部;珠滴上部为后结晶的黄铜矿和其它富铜硫化物。这种元素分布可能对贯入块状硫化物矿石同样适用。碲化物和铋化物在硫化物珠滴中的含量明显高于其在早结晶的浸染状硫化物中的含量,表明富Te和Bi等元素及挥发份的熔体是在岩浆演化后期开始富集结晶的。An unusual multiphase sulfide droplet structure is found in Tulargen large Cu-Ni sulfide deposit,eastern Tianshan, Xinjiang.These droplets,formed by the crystallization of immiscible sulfide liquid,are approximately 5- to 20-mm-sized,and mainly composed of pyrrhotite,pentlandite and chalcopyrite.Field observations show that the droplets,with various geometrical shapes,only occur between sparsely disseminated sulfide and barren pyroxenite.The analyses of 24 sulfide droplets of the Tulargen complex have revealed that the elongated direction of the droplets corresponds with the extended direction of the orebody,which implies that the droplets were reshaped somehow by the magmas during their emplacement up to the middle-upper crust.Accordingly,the shapes of the droplets may imply the ascending paths of the ore-bearing ultramafic silicate melts.Ore microscopy and mineral chemistry studies suggest that the droplets have a geopetal structure with pyrrhotite and pentlandite at the base,chalcopyrite and other Cu-minerals at the top.This feature of metal element distributions may also be applied to massive sulfideore.Moreover,the sulfide droplets have high contents of Te and Bi compared to early crystallized disseminated sulfides,which indicates that trace element- and volatile-rich magmatic melts tend to crystallize at late stage of magma evolvement.

关 键 词：铜镍硫化物矿床 珠滴状构造 通道式成矿 图拉尔根 东天山 

分 类 号：P618.41[天文地球—矿床学]