Two modes of occurrence of eclogites from the Atbashy Range, Southern Tien-Shan, Kyrgyzstan

The eclogite-bearing complexe of the Choloktor suite occurs in the Atbashy Range, Southern Tien-Shan, Kyrgyzstan, and consists of pelitic schists, garnet-amphibolites and eclogites. They have experienced HP and UHP metamorphism with evidence of quartz pseudomorphs after coesite (Tagiri et al., 1995; Puelles and Takasu, 1996; Bakirov et al., 1998). There are non-metamorphosed conglomerates overlying the Choloktor suite and they consist mostly of subrounded cobbles and boulders including eclogites. The eclogites from the Choloktor suite have experienced a prograde metamorphism to the eclogite facies through the greenschist and blueschist facies. The peak metamorphic conditions of the eclogites are estimated as 530- 660°C (Ellis & Green, 1979) and 500-620°C (Powell, 1985) at 15 kbar. Eclogites as the clasts from the conglomerate bed have experienced two events of HP metamorphism. The first HP metamorphic event is defined by inclusions in zoned garnets, which suggest a prograde metamorphism from the greenschist fecies to the eclogite facies. The estimated peak eclogitic conditions are 490-590°C (Ellis & Green, 1979), and 460-560°C (Powell, 1985) at 14 kbar. The second HP metamorphic event is defined by chemically zoned amphiboles in the matrix which show a prograde metamorphism from the greenschist facies through the blueschist facies to the epidote-amphibolite facies. We will discuss the metamorphic relationship between two modes of eclogites, and the study contributes for better understanding of subduction zone metamorphism and exhumation processes of the Atbashy Range, Southern Tien-Shan, Kyrgyzstan. Keywords: Atabshy Range; Southern Tien-Shan; Choloktor suite; conglomerate bed