CuNi-VTiFe复合型矿化镁铁-超镁铁杂岩体岩相学及岩石地球化学特征:以新疆北部为例

Petrographical and lithogeochemical characteristics of the mafic-ultramafic complex related to CuNi-VTiFe composite mineralization:Taking the North Xinjiang as an example

铜镍硫化物矿床和钒钛磁铁矿矿床是镁铁-超镁铁杂岩重要的矿床类型,但二者共生的情况在国内还不多见。新疆北部这类铜镍-钒钛铁复合型矿化岩体较为发育,目前已发现有香山、牛毛泉、土墩南和哈拉达拉等4个岩体属于此类。它们的成岩时代多集中在早二叠世,出露面积在2.8～22km^2,介于通道型铜镍矿化小岩体和大型层状岩体之间,韵律构造发育;岩石组合为超基性-基性-中性岩类,以出现浅色的闪长岩或淡色辉长岩为特点,岩石中金属矿物氧化物(钛铁矿、磁铁矿)和硫化物(黄铁矿、磁黄铁矿、黄铜矿,有时有镍黄铁矿)共存和共生;含矿岩石组合和岩石化学特征与典型铜镍硫化物矿床和钒钛磁铁矿矿床相比,具有重叠和过渡特征;稀土和微量元素特征反映出杂岩体不同岩石类型可能具有相同或相似岩浆来源,是经过强烈分异和演化的产物。新疆北部这类复合型矿化,与北疆地区典型铜镍矿床和典型钒钛磁铁矿矿床,共同构成了新疆北部后碰撞幔源岩浆矿床成矿谱系。

The Cu-Ni sulfide deposit and V-Ti-Fe deposit are important type of deposit related to mafic-ultramafic complex.It is not common that both of them were formed together in China In North Xinjiang,the complex related CuNi-VTiFe composite mineralization is more developed,such as Xiangshan,Niumaoquan,Tudunnan and Haladala.Most of the formation ages of them are Early Permain. The areas of the exposed complex are between 2.8km^2 to 22km^2,and its size is between small rockbody with conduit type Cu-Ni mineralization and large scale layered intrusion.The rhythm structure of the rocks is developed.The rock assemblage of the complex is ultrabasic-basic-intermediate rock,and it's characterized by the presence of leuco-diorite or leuco-gabbro.The oxide(ilmenite, magnetite) was coexisted with the sulfide(pyrite,pyrrhotite,chalcopyrite,on occasion pentlandite) in the rocks.The characters of ore-bearing rock assemblage and lithochemistry represent overlapping and transitional feature,comparing with the characteristics of the classical Cu-Ni sulfide deposit and V-Ti-Fe deposit.Geochemical characteristics of trace elements and rare earth elements show that different rock type of the complex maybe had the same or similar magma-derived and they were the products of intensive magmatic differentiation and evolution.The composite mineralization and typical Cu-Ni sulfide deposit and typical V-Ti-Fe deposit constitute a metallogenic spectrum related to post-collisional mantle-derived magma in North Xinjiang.