Provenance and its variation of the Loess Plateau in China during glacial-interglacial periods: Evidence from detrital zircon and monazite U-Pb chronology

To reveal the provenance and its changes of the Loess Plateau in China (LP) during the glacial and interglacial periods, multi-mineral U-Pb geochronology analysis was conducted. The potential source areas of LP, including the modern sediments of the Qaidam Basin, upper reaches of the Yellow River, the Mu Us Desert, the loess (L5 and L9) and paleosoil (S5 and S9) layers of the Xifeng section, were sampled for detrital zircon and monazite U-Pb dating. The monazite U/Th-Pb age data from the periphery orogenic belt were compared statistically with the detrital monazite age of this study. Results show that the main age peaks of detrital monazite of the LP match the geological records of the northern part of the Tibet Plateau, but significantly differ from the major age components of the North China Craton and the Altai Mountains. There is no obvious difference in the age distribution of detrital zircon U-Pb in glacial loess and interglacial paleosoil, but the age distribution of monazite U-Pb shows certain differences. This study indicated that U-Pb analysis of detrital monazite is able to discriminate the dust contributions from different potential sources of the LP. The dust source of the main-part LP was originated from mainly the northern part of the Tibet Plateau and might transport to the plateau through the Qaidam Basin and/or the central desert. The differences in the source of detrital monazite in loess and paleosoil may reflect the changes in the atmospheric circulation pattern during the glacial and interglacial periods.