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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. Western Kunlun Mountains, LA-ICP-MS zircon dating, Bulunkuole Group, Indosinian, Kangxiwar tectonic zone Citation:Yang W Q, Liu L, Cao Y T, et al. Geochronological evidence of Indosinian (high-pressure) metamorphic event and its tectonic significance in

Tectonic evolution of the Tethys and the boundary between the Gondwanaland and the Eurasia during the Carboniferous and Permian remain hotly debated. Qiangtang region in the Qinghai-Tibet Plateau may be a key place to study these problems. A paleomagnetic study was conducted on the Late Paleozoic rocks in the northern Qiangtang region (33.7°N, 86.7°W), Tibet. Two sites (21 samples) in the Upper Carboniferous, eleven sites (101 samples) in the Permian, and two sites (16 samples) in the Lower Triassic were investigated. The rock magnetic data revealed hematite and magnetite as the main magnetic carriers. In stepwise thermal demagnetization and/or combined alternating field (AC) demagnetization, two characteristic components in the majority of the samples were identified as (1) the Low-temperature Component (LTC), characterized by northerly declination and moderate to steep inclination, corresponding to a pole position overlay with the present North Pole. A minority of the samples present single component, and their directions are the same as (2) the High-temperature Component (HTC) of double components. The combined single-component and HTC data of the Permian can pass the R-test at 95% level and the F-test at 99% level, as well as the BC-test. The pole position from the Late Carboniferous is at 31.8°S, 45.7°E with dp=2.1, dm=3.9, that from the Early and Middle (Late) Permian is at 31. 7°S, 46.8°E with dp=9.2, dm=16.9 (34.4°N, 54.1°E with dp=6.9, dm=12.5) respectively, and that from the Early Triassic is at 16.9°S, 22.5°E with dp=4.9, dm=9.2. These pole positions are different from the other poles for the Qiangtang Block, which suggests the single-component and HTC directions are probably a primary magnetization and the northern Qiangtang Block was paleogeographically

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In the Dabudaer region of the Tianshuihai Massif (Xinjiang, Northwest China), metavolcanic rocks within the mainly metasedimentary Bulunkuoler Group are basalt, basaltic andesite, and rhyolite. In situ zircon U-Pb LA-ICP-MS dating on rhyolite magmatic zircons yielded an age of 2481±14 Ma, interpreted as the eruption age of the Bulunkuoler Group volcanic rocks. The basalt and basaltic andesite are low-Al tholeiite series and the rhyolite is low-Al calc-alkaline series. All of rocks are characterized by enrichment of LREE and LILE (Rb, Th and Ba), depletion of P, Nb, Ta and Ti, and absence of Eu anomalies. The ε Nd (t) of basalts ranges from 3.14 to 4.88 indicating a depleted mantle source. The trace element signatures show that these magmas experienced intense crustal contamination during their ascent. Direct evidence for crustal contamination is the xenocrystic zircons in the ryholite, with ages back to ca. 3300 Ma. The primitive-mantle normalized and Zr/Y-Zr diagrams for the basic volcanic rocks show that they formed in an intra-continental tectonic setting. Combined with the previous studies and compared with North China Craton Neoarchean basic volcanic rocks, it is supposed that the Bulunkuoler Group volcanic rocks reflect the Palaeoproterozoic mantle magma underplating and interaction with felsic crust.

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