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Here we report an integrated study of zircon U-Pb age and Hf isotope composition for a gneiss sample from the Kongling terrain in the Yangtze Craton. CL imaging reveals that most zircons are magmatic, and a few of them have thin metamorphic rims. The magmatic zircons gave a weighted mean U-Pb age of 3218±13 Ma, indicating the gneiss is the oldest basement rock in the Yangtze Craton found to date. They have εHf(t) value of -2.33±0.51,and two-stage Hf model age of 3679±49 Ma,indicating that the gneiss was derived from partial melting of >3.6 Ga crustal rock. The metamorphic rims yielded an age of 2732±16 Ma, implying that the metamorphic event occurred in the Neoarchean era, which may be also a major tectono-thermal event in the Yangtze Craton.
Here we report an integrated study of zircon U-Pb age and Hf isotope compositions for a gneiss sample from the Kongling terrain in the Yangtze Craton. CL imaging reveals that most zircons are magmatic, and a few of them have thin metamorphic rims. The magmatic zircons gave a weighted mean U-Pb age of 3218 ± 13 Ma, indicating the gneiss is the oldest basement rock in the Yangtze Craton found to date. They have εHf (t) value of -2.33 ± 0.51, and two-stage Hf model age of 3679 ± 49 Ma, indicating that the gneiss was derived from partial melting of> 3.6 Ga crustal rock. The metamorphic rims yielded an age of 2732 ± 16 Ma, implying that the metamorphic event occurred in the Neoarchean era, which may be also a major tectono-thermal event in the Yangtze Craton.