A newly discovered Late Cretaceous metamorphic belt along the active continental margin of the Neo-Tethys ocean
نویسندگان
چکیده
Abstract High-grade metamorphic rocks and crustal melts provide crucial evidence for growth differentiation of the continental crust, are widespread in collisional orogens. However, their importance evolution arcs remains poorly understood. Metamorphism related anatexis preserved margin Neo-Tethys ocean serves as a key natural laboratory to investigate this process. Along Neo-Tethyan arc margin, Gaoligong shear zone, Yunnan region China, is an important locality linking Lhasa north with Sibumasu Burma south. Here, Late Cretaceous granulite-facies metamorphism have been identified first time area. Zircon monazite U-Pb dating indicates that S-type granites formed at 87–73 Ma, buried pelitic sediments were simultaneously metamorphosed 75–70 Ma during subduction, all lithologies overprinted by younger 40–30 magmatic strike-slip event India-Asia collision. Phase equilibria modeling high-grade anatectic gneiss MnO-Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2 system peak pressure-temperature (P–T) conditions 780–800 °C 6.5–7.5 kbar defines cooling decompressional P–T path metapelites. This demonstrates within active >20 km depth Ma. In combination record Lhasa, Burma, blocks, extensive belt must along subduction zone. spatially correlates coeval gabbro-diorite suites exposed Gangdese, terranes triggered thinning lithospheric mantle. prolonged mantle-derived magmatism may provided regional-scale heat source ocean.
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Late Cretaceous (~81Ma) high-temperature metamorphism in the southeastern Lhasa terrane: Implication for the Neo-Tethys ocean ridge subduction
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ژورنال
عنوان ژورنال: Geological Society of America Bulletin
سال: 2021
ISSN: ['1943-2674', '0016-7606']
DOI: https://doi.org/10.1130/b35900.1