关键词: 流体成分, 缓冲作用, 湾子岩系, 太行山

Abstract: The Archean metamorphic layering rock series in the Taihang Mountains consist mainly of Al-rich gneiss, various marbles, granulitites and others. There is marked difference in Equilibrium fluids' composition between Al-rich gneiss and marbles. Metamorphic fluid equilibrating with diopside-marble and fosterite-marble presents x(H₂O)=0.02-0.07, however, these equilibrating with Al-rich gneiss has higher water, x(H₂O)=0.27-0.747. There is a great disparity among different rocks in fluid composition in a small area. Fluid composition is controlled by lithology. The mole fraction of water in metamorphic fluid of Al-rich gneiss is higher and the one in marbles is extremely lower, implying that inner buffering plays a leading role in the fluid/rock equilibrium system of the Wanzi layering rock series. This forms a sharp contrast to the fluid/rock equilibrium system with infiltration playing a dominant role in the Fuping gneiss complex. The infiltration of the Fuping gneiss complex and buffering of the Wanzi layering rock series in the fluid/rock equilibrium system suggest that they formed at different tectonic levels of the earth.

Key words: fluid composition, buffers, Wanzi layering rock series, Taihang mountains