内蒙古乌拉山群麻粒岩相岩石的变质温压条件

METAMORPHIC P-T CONDITIONS OF THE ROCKS OF ARCHEAN (WUIASHAN GROUP) GRANULITE FACIES IN INNER MONGOLIA, NORTH CHINA

乌拉山群岩石中的辉石、石榴石、角闪石、黑云母均形成于麻粒岩相条件。二辉石地质温度计和石榴石-黑云母地质温度计和压力计显示,乌拉山群岩石的变质温度为750—850℃,变质压力为0.7—0.9GPa,地温梯度为25.2—28.6℃,属于偏低的中压麻粒岩相。

The rocks Archean (Wulashan group) granulite facies including various kinds of granulites, gneisses and marbles, are distributed in Mt. Daqingshan area of Inner Mongolia and constitute the Archean granulite belt of Mt. Daqingshan. Mineralogical studies indicate that the pyroxenes, garnets, hornblendes and biotites in the rocks of Archean Wulashan group are formed at the high temperature condition of granulite facies. Using orthopyroxene-clinopyroxene geothermometers of Wood-Banno (1973), Wells (1974 ), Lindslay-Dixen (1976) and Nehru-Wyllie (1974) and garnetbiotite geothermometer of Glebouviski (1977) as well as garnet-biotite geobarometer of Glabouviski (1977), it is calculated that the metamorphic temperature and pressure of Wulashan group rocks range between 750-850℃/km and between 0.7—0.9GPa respectively with a geothermal gradient of 25.2—28.6℃/km. belonging to middle pressure granulite facies of metamorphism.