Paleoproterozoic metamorphic event in the nucleus of the Yangtze craton:Evidence from U-Pb geochronology of the metamorphic zircons from the khondalite

Apart from the Archean metamorphic crystal basement, a series of khondalite-bearing graphites and Al-rich minerals are exposed in the Kongling Complex.However, relative to the study of metamorphic crystal basement, geochronological studies of the supracrustal rocks are still very insufficient.In this study, the LA-ICP-MS zircon U-Pb study was carried out for the typical samples of garnet-sillimanite quartzite in the khondalite series.The result shows that the garnet-sillimanite-quartzite was metamorphosed at 1964±12Ma.Combined with the documented zircon U-Pb geochronologic data, the authors hold that the khondalite-series in the Kongling Complex was deposited at 2.1~2.0Ga.The Paleoproterozoic metamorphism and magmatism recognized in the interior of the Yangtze craton are consistent with the worldwide coeval collision-related orogenic event during 2.1~1.8Ga, indicating that this event may have been an important component in the Columbia supercontinent.