Wind-enhanced tectonics in the Qaidam Basin and implications for the source of the Loess Plateau

It is widely assumed that all significant erosion and sediment transport in actively growing mountain belts occurs by fluvial and glacial processes. However, this has not been the case in the Qaidam Basin, located along the actively growing northeastern margin of the Tibetan Plateau in central Asia. Wind erosion in the internally-drained, high-elevation (~3000 m elevation), and hyperarid Qaidam Basin of central Asia has sculpted extensive yardang fields in actively folding sedimentary bedrock. Structural-stratigraphic observations suggest that episodes of severe wind erosion initiated ~2.8 Myr ago and sandblasted rock at sufficient rates (>0.3-1.4 mm/yr) to induce a positive feedback relationship with fold growth. This suggestion of wind-enhanced tectonics is consistent with the history of loess accumulation in central Asia and shortening in the Qaidam region—both became significant during the Miocene and abruptly accelerated 2.8-2.6 Myr ago. We hypothesize that alternating dry/windy and wetter cycles are archived in the Pliocene – Pleistocene stratigraphic record by alternating lacustrine and paleoyardang sequences, akin to and probably in phase with the alternating paleosol-loess sequences of the Loess Plateau located downwind of the Qaidam Basin. The minority view that the Qaidam Basin is a major source of the Loess Plateau in east-central China is additionally supported by the estimated volume of Qaidam Basin material removed by wind (>3.2 × 104 km3; >50% of Loess Plateau volume) and numerical models of dust transport.