SHRIMP single zircon U-Pb dating of the Kongling high-grade metamorphic terrain: Evidence for>3.2 Ga old continental crust in the Yangtze craton

摘要

Single zircons from two trondhjemitic gneisses and two clastic metasedimentary rocks without Eu anomaly of the Kongling high-grade metamorphic terrain are dated by the in situ SHRIMP U-Pb method. The results show that the trondhjemitic magma emplaced at 2947-2903 Ma. Concordant age of as old as 3.3 Ga is present in the detrital zircons from the clastic meta- Sedimentary rocks. Together with the depleted mantle Nd model age (T_DM=3.2-3.3 Ga) of the Clastic metasedimentary rocks, this documents the presence of Paleoarchean continental crust in The Yangtze craton.