Last glacial–Holocene geochronology of sediment cores from a high-altitude Tibetan lake based on AMS 14C dating of plant fossils: Implications for paleoenvironmental reconstructions

Abstract

Abstract We obtained three sediment cores from a high-altitude lake (Lake Pumoyum Co; altitude, ~ 5020 m asl) on the southern Tibetan plateau for reconstruction of environmental changes during the last glacial–Holocene transition. In this study, we established the first reliable chronology for sediment cores from Lake Pumoyum Co, ca. 18.5 cal ka BP at the bottom, by 14C analyses of terrestrial plant residue concentrates (PRC, > 125 μm) and aquatic plant residues. The calibrated ages of the PRC fraction in the surface sediment were nearly modern (0.1 ± 0.1 cal ka BP), and the δ13C values (− 22‰ to − 24‰) were agreed well with those of modern terrestrial C3 plants. In addition, we estimated 14C reservoir ages of macrophyte remains from changes in their δ13C values. The major climate boundary layers in the cores (transitions to Bolling–Allerod, 14.5 ± 0.5 cal ka BP; Younger Dryas, 12.8 ± 0.1 cal ka BP; and Preboreal, ~ 11.6 cal ka BP) were confirmed by our new 14C chronology. The transition to the Bolling–Allerod warm phase from the last glacial (14.5 ± 0.5 cal ka BP) coincided with an obvious lithologic boundary (a rapid decrease in the abundance of the macrophyte remains) in the Lake Pumoyum Co sediment cores.