柴达木盆地西北缘牛鼻子梁铜镍矿矿床特征及其发现意义

牛鼻子梁铜镍矿产于柴达木盆地西北缘古陆块上,其成矿与基性-超基性层状杂岩体有关。共发现3个岩体,其中以Ⅰ号岩体规模较大,出露面积近7km2,其余2个岩体较小。岩体岩石堆晶结构明显,具层状和纹层状构造。Ⅰ号岩体出露岩性以层状淡色辉长岩、闪长岩为主,局部夹超基性岩,代表层状杂岩体上部层序。Ⅱ、Ⅲ岩体以超基性岩石为主,代表层状杂岩体下部层序,是主要的含矿层位。通过槽、钻探验证,在Ⅱ、Ⅲ岩体已发现硫化物铜镍矿体9条,其中,一条矿体的视厚度达41.1m,Ni平均品位为0.5%,最高1.57%。其矿石矿物主要为磁黄铁矿、镍黄铁矿和黄铜矿等,属岩浆熔离改造型矿床,有后期热液叠加。该类型矿床是在柴达木地块周缘首次发现,具有重要的现实意义,其为今后在柴达木盆地周缘寻找与基性-超基性岩有关的铜镍硫化物矿床提供了依据。

The Copper-nickle Mine Features of Niubiziliang in North-west Margin of Chaidamu Basin,and Discoverable Significance

The Niubiziliang eopper-nickle deposit is located in the north-western aneient continental margin of Chaidamu Basin, whose mineralization is relative to mafic-ultramafic layered igneous complex. We found three plutons, of which No. I rock was larger with exposed area of nearly 7kmz , the other two rock was smaller. The rock with striated and layered structure, cumulatic texture is apparent. Exposed litholo- gy of No. I rock was based light-colored layered gabbro, diorite, and local folder mafic rocks, and these rocks are representative of the upper part of layered igneous complex sequence. No.Ⅱand Ⅲ rock are compsed of based mafic and ultramafic rock , which represents the lower layered igneous complex se- quence, with the main seam position. In No. Ⅱ and Ⅲ rock, nine Cu-Ni sulphide ore bodies are identified by few trenching and drilling results. One is indicated by 41. lm apparent thickness with 0.5 % average Ni grade, the highest 1.57 %. Ore minerals include magnetic pyrite, nicopyrite, chalcopyrite etc. The deposit belongs to the type of magmatie liquation with post hydrothermal solution superposition. It has very im- portant the firs tramafi significance that this type of deposit suggests that it is identified in the Chaidamu block margin for t time; it provided strong evidence for searching Cu-Ni sulphide deposits associated with mafic-ul- c rocks in the margin of Chaidamu Basin.