Origin and evolution of the Tengchong block, southeastern margin of the Tibetan Plateau: Zircon U–Pb and Lu–Hf isotopic evidence from the (meta-) sedimentary rocks and intrusions

• The paragneisses in Gaogigongshan Grp. deposited in the Late Paleozoic.
• The Tengchong block originated from Indian margin.
• The crust activated after Paleozoic.

U–Pb ages and Hf isotopic data from detrital zircons of Gaoligongshan metamorphic complex and the Carboniferous Menghong Group and igneous zircons from intrusions constrain the origin, tectonic affinity (East Gondwana), crustal evolution processes, and the properties of regional high-grade metamorphic rocks in the Tengchong block of southeastern China. Three granites intruded into the Tengchong block at ~ 72 Ma, ~ 114 Ma and ~ 122 Ma. Detrital zircons range in age from Archean to Late Ordovician for both the Carboniferous Menghong Group and the Gaoligongshan metamorphic complex. Analyses for these two units yield similar age clusters at ~ 2.5 Ga, ~ 1.6 Ga, ~ 1.17 Ga, ~ 0.95 Ga, and ~ 0.65–0.5 Ga as well as parallel Hf isotopic distributions. The protolith of the studied Gaoligongshan complex in the Tengchong block should deposit in the Late Paleozoic. Detrital zircon age distribution patterns of the Carboniferous Menghong Group and the Gaoligongshan complex show dominant younger Grenvillian age peaks at ~ 0.95 Ga, indicating the strong paleogeographic connection of the Tengchong block with the Indian margin. The Hf isotopic comparison of both detrital and igneous dated-zircon shows that the Tengchong block can be represented by the post-Archean Indian continental margin. After 250 Ma, the intensive magma events affected the region and considerable juvenile material accreted to the crust of the Tengchong block.

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