西藏改则县铁格隆地区含矿玢岩特征与成因探讨

铁格隆地区含矿岩石以闪长玢石及石英闪长玢岩为主,属钙碱性岩系和高钾钙碱性岩系,显示I型花岗岩的特点。岩体形成于早白垩世班公湖-怒江洋盆俯冲消减构造环境,成岩岩浆属氧化型岩浆,来源于壳幔结合部,并受到壳源物质的强烈混染。与玉龙、冈底斯斑岩矿带含矿岩石进行对比,该含矿玢岩在岩石类型、岩石化学、地球化学及成岩构造环境等方面均存在明显差异,指示其成矿动力学背景、成矿机理与"碰撞"及"碰撞后"的斑岩型矿床不同,属形成于"岛弧"环境的斑岩型铜金矿床。

Genesis of the ore-bearing porphyrite in Tiegelong, Gerze, Xizang

The ore-bearing rocks in Tiegelong,Gerze,Xizang consist of dioritie-porphyrite and quartz diorite-porphyrite which are assigned to the calc-alkaline and high-K calc-alkaline rock series characteristic of I-type granites.These rocks resulted from the tectonic settings of the Early Cretaceous Bangong Lake-Nujiang oceanic basin subduction.The rock-forming magmas comprise oxidized magmas derived from the juncture of the crust and mantle and are highly contaminated by the crust-derived matter.There are gaps in rock type,petrochemistry,geochemistry and tectonic setting for the ore-bearing rocks from the Yulong and Gangdise porphyry belts and the copper-gold deposits in the study area,implying that the copper-gold deposits in the study area should belong to the "ialsnd-arc" porphyry-type copper-gold deposits varying from the "collision" and "post-collision" porphyry-type deposits in geodynamic setting and mineralization mechanism.