热液矿床石英铅同位素组成及其地质意义

LEAD ISOTOPIC COMPOSITION OF QUARTZ IN HYDROTHERMAL ORE DEPOSITS AND ITS GEOLOGICAL SIGNIFICANCE

作者以若尔盖铀矿床为例,研究了含矿热液形成的石英脉石英的铅同位素组成,并将其作为联系母源铅同位素组成的桥梁,判别铀的来源。结果表明,矿床中石英铅同位素组成与含矿黄铁矿和中酸性构造-岩浆成因的花岗岩铅同位素组成具线性演化关系。由此提出含矿热液中的铀来自中酸性构造-岩浆岩而不是地层岩石的新见解,同时提出利用热液石英铅同位素组成判别非放射性矿床成矿元素来源的可能性。

The writers have studied the Pb isotopic composition of quartz in hydrothermal quartz veins in the Zoige uranium deposit, and regard Pb isotopic ratios of quartz as a bridge linking up the Pb isotopic of the composition parent rocks with that of ores to determine the source of U. The results indicate that the Pb isotopic composition of the quartz in the deposit has a relationship of linear evolution with the Pb isotopic compositions of U-bearing pyrite and intermediate-acid tectono-magmatic granite. So the writers advance a new view that U in hydrothermal ore solutions was derived from intermediate-acid tectonomagmatic rocks rather than stratigraphic rocks, and propose the possibility of using the Pb isotopic composition of hydrothermal quartz to distinguish the sources of ore elements of non-radioactive deposits.