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The CL images,LA-ICP-MS in situ trace elements analysis,and U-Pb dating for zircons indicate that the metamorphic ages of the sillimanite-garnet-biotite gneiss and the garnet-amphibole gneiss from eastern Taxkorgan of the Western Kunlun Mountains are 220±2 and 220±3 Ma respectively,and their protolith ages are younger than 253±2 and 480±8 Ma respectively.Two samples were collected at the same outcrops with HP mafic granulite and HP pelitic granulite.Mineral assemblage of the sillimanite-garnet-biotite gneiss(Grt+Sill+Per+Q) is consistent with that of HP pelitic granulite at early high amphibolite-granulite facies stage.Mineral assemblage of the garnet-amphibole gneiss(Grt+Amp+Pl+Q) is consistent with retro-metamorphic assemblage of HP mafic granulite at amphibolite facies stage.The dating results suggest that these HP granulites underwent peak metamorphism at 220±2 to 253±2 Ma.Thus,the Kangxiwar tectonic zone was probably formed by subduction and collision of the Paleo-Tethys Ocean during Indosinian.Protolith ages of the two samples,together with previously published U-Pb zircon dating age,suggest that the sillimanite-garnet schist-quartzite unit is a late Paleozoic unit,not a part of the Paleoproterozoic Bulunkuole Group.
The CL images, LA-ICP-MS in situ trace elements analysis, and U-Pb dating for zircons indicate that the metamorphic ages of the sillimanite-garnet-biotite gneiss and the garnet-amphibole gneiss from eastern Taxkorgan of the Western Kunlun Mountains are 220 ± 2 and 220 ± 3 Ma respectively. And their protolith ages are younger than 253 ± 2 and 480 ± 8 Ma respectively. Two samples were collected at the same outcrops with HP mafic granulite and HP pelitic granulite. Mineral assemblage of the sillimanite- garnet-biotite gneiss (Grt + Sill + Per + Q) is consistent with that of HP pelitic granulite at early high amphibolite-granite facies stage. Mineral assemblage of the garnet-amphibole gneiss (Grt + Amp + Pl + Q) is consistent with retro-metamorphic assemblage of HP mafic granulite at amphibolite facies stage. the dating results suggest that the HP granulites underwent peak metamorphism at 220 ± 2 to 253 ± 2 Ma.Thus, the Kangxiwar tectonic zone was probably formed by subduction and collision of the Paleo -Tethys Oce an during Indosinian. Protolith ages of the two samples, together with previously published U-Pb zircon dating age, suggest that the sillimanite-garnet schist-quartzite unit is a late Paleozoic unit, not a part of the Paleoproterozoic Bulunkuole Group.