Variability and environmental significance of organic carbon isotopes in Ganzi loess since the last interglacial on the eastern Tibetan Plateau.

• Detailed investigation on the δ13C org of the Ganzi loess-paleosol sequence. • Loess δ13C org values in glacial periods are lower than those in interglacial period. • The paleovegetation is mainly dominated by C 3 vegetation since LIG. • The abundance of C3/C4 vegetation has been mainly controlled by climate change. The stable carbon isotope composition of total organic matter (δ13C org) in loess deposits has been widely used as a valuable proxy for reconstructing terrestrial paleovegetation. Aeolian loess is widely distributed on the high Tibetan Plateau (TP); however, little is known about the variability and paleoenvironmental implications of the δ13C org of Tibetan loess. We conducted detailed δ13C org and total organic carbon analyses of the Ganzi loess sequence on the eastern TP since the last interglacial (LIG). Our results indicate that the δ13C org values of loess during glacial periods were lower than those during interglacial periods, with more negative values associated with the cold stages since the LIG on the eastern TP. The reconstruction of vegetation from the δ13C org data indicated that C 3 /C 4 mixed vegetation was dominated by C 3 vegetation, and that the relative abundance of C 4 vegetation during the glacial stages was much lower than that during MIS 5 and MIS 3. The high relative abundance of C 4 plants during MIS 5 and MIS 3 suggested an increased proportion of C 4 plants during the warm period. Since the LIG, the change in the abundance of C 3 /C 4 vegetation in the Ganzi region has been mainly controlled by climate change at the glacial–interglacial scale. The combined effect of temperature, precipitation, and atmospheric CO 2 caused changes in the paleovegetation on the eastern TP. [ABSTRACT FROM AUTHOR]