苏州花岗岩中钽矿化机理的研究

Study of Mineralized Mechanism Ta in Suzhou Granite, Jiangsu Province

苏州花岗岩岩体中稀有元素含量远高于克拉克值，在岩体中Ｔａ／Ｎｂ比值从下向上逐渐升高，边缘相中Ｔａ含量要比内部相高出４～５倍，氧同位素分析表明边缘相样品δ１８Ｏ的亏损是受到雨水交换作用的强烈影响。综合考察苏州花岗岩边缘相的雨水交换与富集稀有元素的岩浆体系之间的关系，可以认为苏州花岗岩在演化结晶至晚期时，在顶部和边缘与雨水热液作用，导致岩浆物理化学条件改变，使稀有元素络合物发生解体，从而发生Ｔａ矿化作用。

The content of rare elements is much higher than the Clarke value in Suzhou granite mass.From bottom to top,Ta/Nb increases gradually and the content of Ta in the border facies is 4 5 times higher than that of internal facies within the mass.The oxygen isotope shows that the loss of S 18 O in the border facies is affected strongly by the rainwater. By comprehensive investigation on the relation between rainwater exchange and magmatic system enriched with rare elements in border facies in Suzhou granite mass,it is considered that there occurs changes of physical chemical conditions of magma because of the reaction with rainwater hydrothermal solution on the top and border of the mass during late crystallization. So,rare elements complexes have been disintegrated which result in Ta mineralization.