Timing and spatial distribution of loess and loess-like sediments in the mountain areas of the northeastern Tibetan Plateau

- Holocene aeolian sediments and paleosol indicate different periods of landscape activity.
- Holocene soil formation occurred around about 8.5 to 7 ka and 5.5 to 4 ka.
- Holocene soil formation can be associated with periods of more humidity.

Most studies on landscape evolution on the Tibetan Plateau during the late Quaternary have mainly focused on using lacustrine records. However, mantles of sandy silt and paleosols also provide valuable archives for reconstructing Holocene paleoenvironmental change. Yet little is known about the distribution and timing of these late Quaternary aeolian sediments. To enhance understanding and knowledge of aeolian sediments in Tibet and to help reconstruct the nature of Late Glacial through mid-Holocene landscape development, a loess-paleosol sequence, the Suohuduo section, located at the eastern margin of the Tibetan Plateau at about 4000 m above sea level is examined using sedimentological, geochemical and geochronological methods. A chronostratigraphy is established using nine optically stimulated luminescence and one radiocarbon ages. Sedimentation increased during the Late Glacial and the early Holocene with an upwards fining of sediments in the lower part of the section. Two mid Holocene paleosols that date to about 8.5 ka to 7 ka and ~ 5.5 ka to 4 ka reflect more humid climate conditions during the mid-Holocene than earlier times. The upper part of the section is mainly silt, which reflects a more open landscape with higher aridity since 4 to 3 ka this time. These data support evidence for similar climate/paleoenvironmental change in adjacent regions on the Tibetan Plateau.