Details

Autor(en) / Beteiligte

• WU, Y.-B.
• GAO, S.
• GONG, H.-J.
• XIANG, H.
• JIAO, W.-F.
• YANG, S.-H.
• LIU, Y.-S.
• YUAN, H.-L.

Titel

Zircon U-Pb age, trace element and Hf isotope composition of Kongling terrane in the Yangtze Craton: refining the timing of Palaeoproterozoic high-grade metamorphism

Ist Teil von

• Journal of metamorphic geology, 2009-08, Vol.27 (6), p.461-477

Ort / Verlag

Oxford, UK: Blackwell Publishing Ltd

Erscheinungsjahr

2009

Quelle

Wiley Online Library

Beschreibungen/Notizen

• U–Pb age, trace element and Hf isotope compositions of zircon were analysed for a metasedimentary rock and two amphibolites from the Kongling terrane in the northern part of the Yangtze Craton. The zircon shows distinct morphological and chemical characteristics. Most zircon in an amphibolite shows oscillatory zoning, high Th/U and 176Lu/177Hf ratios, high formation temperature, high trace element contents, clear negative Eu anomaly, as well as HREE‐enriched patterns, suggesting that it is igneous. The zircon yields a weighted mean 207Pb/206Pb age of 2857 ± 8 Ma, representing the age of the magmatic protolith. The zircon in the other two samples is metamorphic. It has low Th/U ratios, low trace element concentrations, variable HREE contents (33.8 ≥ LuN≥2213; 14.7 ≤ LuN/SmN ≤ 354) and 176Lu/177Hf ratios (0.000030–0.001168). The data indicate that the zircon formed in the presence of garnet and under upper amphibolite facies conditions. The metamorphic zircon yields a weighted mean 207Pb/206Pb age of 2010 ± 13 Ma. These results combined with previously obtained Palaeoproterozoic metamorphic ages suggest a c. 2.0 Ga Palaeoproterozoic collisional event in the Yangtze Craton, which may result from the assembly of the supercontinent Columbia. The zircon in two samples yields weighted mean two‐stage Hf model (TDM2) ages of 3217 ± 110 and 2943 ± 50 Ma, respectively, indicating that their protoliths were mainly derived from Archean crust.