Zircon U–Pb geochronology, geochemistry and tectonic implications of Triassic A-type granites from southeastern Zhejiang, South China

摘要: Abstract The late Permian–Triassic granites in southeastern China have important tectonic significance for the evolution of East Asia. A detailed study utilizing zircon U–Pb dating, major and trace element geochemistry, Hf isotope geochemistry Dashuang Jingju Zhejiang Province, South was performed. LA-ICP-MS analyses yielded ages quartz-monzonite monzogranite that are 234 ± 3 Ma 231 ± 3 Ma, respectively, from pluton, while K-feldspar granite pluton 246 ± 2 Ma 241 ± 3 Ma, respectively. These indicate magmatism event took place during early Triassic to Mid-Triassic. two high contents total alkalis (Na 2 O + K O = 7.73–10.24%), high-field-strength elements (e.g., Zr = 215–471 ppm, Y = 25.8–36.5 ppm, Nb = 15–28 ppm, Zr + Nb + Ce + Y = 293–849 ppm) rare earth (total REE = 299–701 ppm), as well Ga/Al ratios (10,000 × Ga/Al = 2.44–2.9). saturation temperatures were 800–837 °C granites, which suggests they petrographic geochemical characteristics A-type granites. In-situ isotopic revealed e ( t ) values ranging −20 −6 two-stage depleted mantle model 1.6 Ga 2.6 Ga, magmas formed by partial melting Paleoproterozoic crust rocks Cathaysia Block. series distributed coastal region probably defines an extensional environment Triassic.