Abstract

Info

Title:: Provenance Identification for Sedimentary Sequence of Red Clay in Loess Plateau Based on Zircon U-Pb Ages

Author(s):: XIE Wen-bin; GONG Hu-jun; Department of Geology, Northwest University, Xi’an 710069, Shaanxi, China

Keywords:: red clay; sedimentary sequence; provenance identification; zircon U-Pb age; paleoclimate; Loess Plateau

Abstract:: The widely deposited Neogene red clay sequence in Loess Plateau has important directive significance on East Asian paleoclimate. The comparison of the detrital zircon U-Pb ages of 7.0, 6.5, 5.5, 3.2 Ma from Lingtai red clay section in Gansu and 6.56, 5.24, 3.50 Ma from Baode red clay section in Shanxi was studied; the comparison of the detrital zircon U-Pb ages from red clay in Loess Plateau and the peripheral potential provenance regions was also studied. The results show that the sedimentary source of red clay in Loess Plateau has a spatial homogeneity and temporal variation. According to the difference of sedimentary sources, the red clay sediment in Loess Plateau can be divided into three stages: the first stage (5.7-7.0 Ma), the main sources are West Kunlun Mountain and Pamir Plateau; the second stage (3.4-5.7 Ma), the main source is Taklimakan desert; the third stage (2.6-3.4 Ma), the main source is Alxa area. The variation of provenance from red clay sediment shows that the west wind weakens and monsoon grows at 2.6-7.0 Ma, and the two changes of provenances correspond to Messina salinity crisis at ~5.7 Ma and the uplift of QinghaiTibet Plateau at ~3.4 Ma, respectively. In general, the important factors influencing the eolian deposition in Loess Plateau are the uplift of Qinghai-Tibet Plateau and the western mountains of China, and the Tethys ocean evolution under the control of plate motion.