Deciphering the origin of the Tengchong block, west Yunnan: Evidence from detrital zircon U–Pb ages and Hf isotopes of Carboniferous strata

• Detrital zircons show ~ 2.5, 1.7–1.4, ~ 0.95, and 0.65–0.5 Ga age groups.
• The εHf(t) values of each age group show very wide range.
• The Tengchong block was located at the Indian Gondwana margin in Early Paleozoic.
• In Grenvillian and Pan-African, crustal growth of provenances was insignificant.

To constrain the paleoposition of the Tengchong block within Gondwana during the Early Paleozoic, we performed in-situ U–Pb and Hf isotope analyses on detrital zircons from Carboniferous strata in the Tengchong block. The age distributions yield dominant Neoarchean (~ 2.5 Ga), Mesoproterozoic (1.7–1.4 Ga), Grenvillian (~ 0.95 Ga), and Pan-African (0.65–0.5 Ga) age groups. Hf isotope compositions of Mesoproterozoic, Grenvillian, and Pan-African zircon age groups exhibit wide range of εHf(t) suggesting their diverse sources. The oldest Hf model ages indicate that the source magma included reworked Eoarchean (3.8–3.7 Ga) crustal materials. The remarkable resemblance of zircon age spectra and Hf isotopes from the Tengchong block with those from Tethyan Himalayan, western Qiangtang and Indochina suggests that the Tengchong block was located along the Indian margin of Gondwana during the Early Paleozoic. In Grenvillian and Pan-African, crustal growth for the source areas was insignificant.

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