Discovery of the oldest (~2.87 Ga) granitic gneisses in the Qinling–Dabie orogenic belt: Direct evidence for Mesoarchean crust

Our paper reports the first discovery of ~2.87Ga granitic gneisses from the Susong Complex, a possible Precambrian microcontinent exposed in the southeastern part of the Dabie orogen. The granitic gneisses are the oldest known rocks in the Phanerozoic Qinling–Dabie orogenic belt, which form a rare Mesoarchean rock archive that can be used as important “geologic barcodes” for terrane correlations. Our results from high-precision zircon U-Pb dating indicate that Archean crust of the Yangtze Block, as old as the Mesoarchean, was extended into the Qinling–Dabie orogenic belt, and Archean crust of the Yangtze Block was more widespread than previously recognized.