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内蒙古太古宙麻粒岩相岩石中变质矿物极为发育,分布广泛。变质矿物主要有石馏石、辉石、角闪石、黑云母、矽线石、斜长石等。变质岩中主要矿物的生成与原岩性质有密切关系,矿物成分直接受岩石成分所控制。利用二辉石地质温度计,采用 Wood 和 Banno 方法所获得的温度为756—890℃,Wells 方法所获得的温度为780—980℃,两种方法所获得的温度是比较吻合的。用黑云母-石榴石地质温度计, 采用 Perchuk 图解和公式获得的温度为630—741℃。二辉石获得的温度代表了本区麻粒岩相变质作用的最高温度,而黑云母-石榴石对获得的温度可能代表了本区变质作用的最低温度。故可认为,本区麻粒岩相变质作用的温度范围为750—900℃。根据岩石类型和矿物共生组合特点推测和计算的压力约(7—10)×10~5kPa,属中压相系的麻粒岩。
The metamorphic minerals in the Archean granulite facies in Inner Mongolia are highly developed and widely distributed. Metamorphic minerals are mainly pyrites, pyroxene, hornblend, biotite, sillimanite, plagioclase and so on. The formation of the main minerals in the metamorphic rocks is closely related to the nature of the original rocks. The mineral composition is directly controlled by the rock composition. The temperature obtained by Wood and Banno method is 756-890 ° C using the pyroxene geothermometer and 780-980 ° C by the Wells method. The temperatures obtained by the two methods are in good agreement. Using a biotite-garnet geothermometer, the temperature obtained using the Perchuk plot and formula was 630-741 ° C. The temperature obtained from the diopside represents the highest temperature of granulite facies metamorphism in the area, whereas the temperature obtained from biotite-garnet may represent the lowest temperature of metamorphism in this area. Therefore, it can be considered that the temperature range of granulite facies metamorphism in this area is 750-900 ℃. Based on the rock type and the characteristics of the symbiotic assemblage of mineral, the pressure estimated and calculated is about (7-10) × 10 ~ 5kPa, which belongs to the medium-pressure facies granulite.