赣中周潭群变质脉体的微量元素及氧同位素地球化学研究

Study on Oxygen Isotope and Trace Element Geochemistry of Metamorphic Veins within Zhoutan Group in Central Jiangxi Province

笔者等对周潭群沉积变质岩及其中脉体的微量元素、氧同位素地球化学进行了研究,结果表明,变质石英脉继承了其围岩的稀土元素及氧同位素地球化学特征,表明形成石英脉的流体来源于围岩;脉体的微量元素对Zr—Hf、U—Th、Nb—Ta和Y—Ho与变质岩有一定的差异,且有一定的分异,指示脉体是流体作用的产物。变质流体通过侧向扩散作用形成了周潭群变沉积岩中的变质脉体。

Trace element and oxygen isotope geochemical studies of the metamorphic veins and their host metasedimentary rocks of the Zhoutan Group at two localities, Xiangshan and Yihuang, in central Jiangxi Province have been conducted in this paper. The results show that the metamorphic quartz veins inherited the REE and oxygen isotope geochemical characteristics from their host rocks, suggesting that the vein-forming fluids were from the host rocks. Additionally, trace element pairs Zr-Hf,Nb-Ta,Y-Ho and U-Th of the veins have to certain degree fractionation being little different from those of their host rocks. This also indicates that the veins are the products of the fluids. The metamorphic veins within the Zhoutan Group metasedimentary rocks were formed principally by lateral diffusion of the metamorphic fluids.