西藏勒青拉铅锌矿床稀土元素地球化学特征

文章通过对西藏勒青拉铅锌矿床稀土元素的研究,判定矿石与地层(灰岩)有着相同的稀土元素特征,同时矿石与岩浆岩也有着密切的关联.夕卡岩全岩的稀土元素分布模式表现出承袭了围岩的分布模式,与长江中下游地区的夕卡岩矿床相比表现出截然不同的特征,造成这一现象的主要原因可能是由于岩体距碳酸盐岩地层(围岩)较远,热液需经过构造等通道的远距离运移后才能流经围岩并与其发生接触交代作用,而在接触交代作用过程中,热液又萃取了大量地层中的成矿物质所造成.稀土元素相关的特征值变化表明在成矿过程中,成矿温度逐渐降低,成矿环境从相对还原条件向相对氧化条件改变.

REE GEOCHEMISTRY OF LEQINGLA Pb-Zn DEPOSIT IN TIBET

Based on study on REE geochemistry of Leqingla Pb -Zn deposits in Tibet, REE in ores and strata limestone have the same characters, and ores axe closely related with magmatic rocks. REE pattern of skarn ores inherited the distributive mode of wallrocks, and is rather different from that in middle - lower Yangtze area. The difference lies in that magraatic rocks in the Leqingla deposit is far from carbonate wallrocks, and there exists a long way transportation for ore -forming fluids to act contact metasomatism with wallrecks. During contact metasomatism, ore -forming fluids extracted ore - forming materials from wallrocks. Variation of REE features shows that during decreasing of mineralizing temperature, mineralizing conditions change from relative reducing environment to relative oxidation environment.