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

Abstract

article i nfo To constrain the paleoposition of the Tengchong block within Gondwana during the Early Paleozoic, we per- formed 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 eHf(t) suggesting their diverse sources. The oldest Hf model agesindicate that thesource magma included reworked Eoarchean(3.8-3.7 Ga) crustal materials. The re- markable 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.