Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divide...Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divided in terms of their peak temperature of metamorphism. Medi-um-temperature eclogites (MT), as Group B, occur in the Dabie Group. They were formedfrom epidote-amphibolite facies. The metamorphism of eclogite facies has two stages: the co-esite eclogite facies stage (the peak condition: T = 600-700℃, P = 2. 7 - 3. 0 GPa) and theglaucophane eclogite facies stage (the pressure decreases, may be lower than 2. 5 GPa while thetemperature has little change). Low temperature eclogites (LT), as Group C, occur in the Qi-jiaoshan Formation. They were formed from blue schist facies (the peak condition: T = 490 -560℃, P< 1. 5 GPa). The appearance of hydrous minerals in the eclogites indicates the im-portant role of water in metamorphism. Medium-temperature eclogites are different from low-temperature ones in metamorphism. At last, the evolution of the high-pressure metamorphicbelt is discussed as well.展开更多
文摘Eclogite facies rocks in this area are diverse in rock type. The field occurrence androck-chemistry reflect their in-situ origin. Based on their regional geology and field occurrence,two groups of eclogites are divided in terms of their peak temperature of metamorphism. Medi-um-temperature eclogites (MT), as Group B, occur in the Dabie Group. They were formedfrom epidote-amphibolite facies. The metamorphism of eclogite facies has two stages: the co-esite eclogite facies stage (the peak condition: T = 600-700℃, P = 2. 7 - 3. 0 GPa) and theglaucophane eclogite facies stage (the pressure decreases, may be lower than 2. 5 GPa while thetemperature has little change). Low temperature eclogites (LT), as Group C, occur in the Qi-jiaoshan Formation. They were formed from blue schist facies (the peak condition: T = 490 -560℃, P< 1. 5 GPa). The appearance of hydrous minerals in the eclogites indicates the im-portant role of water in metamorphism. Medium-temperature eclogites are different from low-temperature ones in metamorphism. At last, the evolution of the high-pressure metamorphicbelt is discussed as well.
