内蒙古嘎仙钴镍硫化物矿床的地质特征及成因探讨

Geological characteristics and genesis of the Gaxian Co-Ni sulfide deposit,Inner Mongolia

大兴安岭北段的嘎仙矿床为一大型低品位钴镍硫化物矿床。矿床主要以浸染状、细脉—网脉状产于蚀变的超基性岩石中。赋矿岩石为一套科马提岩质的堆晶岩和火山熔岩,并与科马提质凝灰岩、玄武岩、玄武质凝灰岩、沉凝灰岩、碳酸盐岩构成岩套。嘎仙矿床的成因类型为热液型硫化镍矿床。矿床的形成与燕山期构造和岩浆活动密切相关,成矿发生在构造活动由挤压剪切向松弛伸展的转变阶段,矿区发育的碱长花岗岩与花岗斑岩、石英粗面斑岩等可能为同一岩浆演化的产物,均具有富水、含S特征,矿化与高演化的富碱斑岩有直接关系。

The Gaxian deposit located in the northern section of Daxinganling mountain, is a largesized low grade cobalt-nickel sulfide deposit. The mineralization mainly occurs in the altered ultramafic rock in forms of disseminated, veinlet and stockwork types. Ore-bearing rocks are komatiitic cumulate and volcanic lava which constitute a rock suite with komatiitic tuff, basalt, basaltic tuff, tuff, and carbonate rock. The genetic type of the Gaxian deposit may be classified into a hydrothermal type nickel sulfide deposit. The metallogenesis is closely related to Yanshanian tectonic and magmatic activities. Mineralization occurs in the transitional tectonic stage from compression shear deformation to extensional deformation.The widely distributed alkali-feldspar granite may be derived from a same magma as granite porphyryand quartz trachyte porphyry, all of them have same charaeterisrtics with water-rich and sulfur-rich. Mineralization is directly associated with high degree evoluted alkali-rich porphyry.