Eclogite facies rocks in this area are diverse in rock type,The field occurrence and rock-chemistry reflect their in-situ origin.Based on theri regional geology and field occurrence,two groups of eclogites are divided are divided in terms of their peak temperature of metamorphism.Medium-temperature eclogites(MT),as Group B,occur in the Dabie Group,They were formed from epidote-amphibolite facies.The metamorphism of eclogite facies has two stages:the coesite eclogite facies stage(the peak condition:T=600-700℃,P=2.7-3.0GPa)and the glaucophane eclogite facies stage(the pressure decreases,may be lower than 2.5 GPa while the temperature has little change),Low temperature eclogites(LT),as Group C,occure in the Qijiaoshan Formation,They were formed from blue schist facies (the peak condition:T=490-560℃,P<1.5GPa),The appearance of hydrous minerals in the eclogites indicates the important role of water in metamorphism.Medium-temperature eclogites are different from lowtemperature ones in metamorphism.At last,the evolution of the high-pressure metamorphic belt is discussed as well.
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