Low temperature eclogite facies metamorphism in Western Tianshan, Xinjiang

According to the field occurrences and petrological study, the low temperat ure eclogite facies metamorphic rocks in Western Tianshan of Xinjiang can b e divided into five types: (i) massive glaucophane-epidote eclogites and gl aucophane-paragonite eclogites; (ii) schistose or gneissic mica eclogites; (iii) banded calcite eclogites; (iv) pillow glaucophane eclogites; (v) garn et-omphacite quartzites. Their eclogite facies metamorphism has undergone f our stages of evolution: (i) pre-peak lawsonite-blueschist facies stage, T = 350-4000 degreesC, P = 0.7-0.9 GPa; (ii) peak eclogite facies stage, T = 530 +/- 20 degreesC, P = 1.6-1.9 GPa; (iii) retrograde epidote-blueschist f acies stage, T=500-530 degreesC, P = 0.9-1.2 GPa and (iv) retrograde bluesc hist-greenschist facies stage, T = 450-550 degreesC, P = 0.7-0.8 GPa. The m etamorphic PT path of Western Tianshan eclogites is characterized by clockw ise ITD resulting from the subduction of Tarim plate northward to Yili-Cent ral Tianshan plate followed by fast uplift to the surface. But there were a t least two stages of blueschist facies retrograde metamorphism overprinted during their uplift.