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7480404 
Journal Article 
High-pressure granulites from Eastern Himalayan Syntaxis: P-T path, zircon U-Pb dating and geological implications 
Liu, F; Zhang, L 
2014 
30 
10 
2808-2820 
Chinese 
CCC:000344215200002 
Along Yalu-Tsangpo River, Eastern Himalayan Syntaxis, expose high-pressure mafic granulites. Peak stage assemblage of high-pressure mafic granulite is garnet + clinopyroxene + quartz + rutile. The reaction plagioclase + orthopyroxene→clinopyroxene + garnet + quartz indicates peak pressure exceeded the orthopyroxene-out pressure. The peak conditions of high-pressure mafic granulite are 904°C and 1. 37GPa. Zircon U-Pb dating shows that the age of high pressure granulite facies metamorphism is 20. 7 ± 2. 3Ma. Amphibole-orthopyroxene granulite is the product of the first stage retrograde metamorphism, and the assemblage is orthopyroxene + amphibole + plagioclase + quartz + ilmenite + magnetite, and the P-T conditions are < 0. 6GPa and 720 ∼ 760°C. The overprinted amphibolite facies assemblage is amphibole + plagioclase + quartz + ilmenite + magnetite and the P-T conditions are < 0. 6GPa and > 745°C. The age of metamorphic zircon in amphibole-orthopyroxene granulite is 9. 38 ±0. 22Ma. According to the inclusions amp + pl + qz in such zircon, this age represents the age of amphibolite facies metamorphism. Therefore, the P-T-t path of the high-pressure granulites from Eastern Himalayan Syntaxis is clockwise and it represents a two-stage exhumation process, i. e. the first stage of exhumation: from the depth of high-pressure granulite facies to the depth of amphibolite facies beginning at about 20Ma; the second stage of exhumation: from the depth of amphibolite facies to the earth surface beginning at about 9Ma. According the P-T conditions and the results of U-Pb zircon dating, the average exhumation rates for these two stages are 2. 4mm/y and 2. 3mm/y, respectively. Our study is consistent with the opinion of two-stage uplifts of Tibetan Plateau and further proves that the uplift of Tibetan Plateau connects tightly with the exhumation of subduction zone. 
Eastern Himalayan Syntaxis; High-pressure granulites; P-T path; Tibetan Plateau; Zircon U-Pb dating; Feldspar; Garnets; Igneous rocks; Ilmenite; Magnetite; Metamorphic rocks; Oxide minerals; Silicate minerals; Structural geology; Geochronology