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闽北麻源群在空间上表现为巴罗式递增变质带：绿泥石带→黑云母带→石榴石带→十字石带→蓝晶石带→夕线石带。变质温度计算结果表明，区内蓝晶石带变质温度（４７０℃～５００℃）明显低于石榴石带和十字石带变质温度（５００℃～５５０℃），即蓝晶石带在石榴石带和十字石带之前出现。这显然与传统的递增变质带理论相悖。流体组成化学平衡计算和变质反应热力学分析研究表明，蓝晶石带较低的变质温度并非是压力或退化变质作用所致，而是低ＸＨ２Ｏ流体对形成蓝晶石的脱水变质反应温度缓冲的结果，缓冲温度值高达１００℃～２００℃。本文从热力学理论上解释了缓冲作用的机制并估算了缓冲的温度范围，据此讨论了变质流体在变质相带研究方面的重要意义。
The Mayuan Group in North Fujian showed spatially Barr type progressive metamorphic belt: chlorite belt → biotite belt → garnet belt → cross belt → kyanite belt → stilbore belt. The metamorphic temperature calculation results show that the metamorphic temperature of the kyanite zone (470 ℃ ~ 500 ℃) is obviously lower than that of the garnet belt and the metamorphic zone (500 ℃ ~ 550 ℃), that is, And before the cross stone belt. This is obviously contrary to the traditional incremental metamorphic theory. Chemical compositions of fluid composition and thermodynamic analysis of metamorphic reaction show that the lower metamorphic temperature of kyanite is not caused by pressure or degenerated metamorphism but rather the result of temperature buffering of dehydration and metamorphic reaction of kyanite formed by low XH2O fluid , The buffer temperature value up to 100 ℃ ~ 200 ℃. In this paper, the mechanism of buffer action is explained theoretically by thermodynamics and the temperature range of buffer is estimated. The importance of metamorphic fluids in the study of metamorphic facies is discussed.