Fig. 1: Site location.

a Topographic map of the present-day Tibetan Plateau region with relevant atmospheric features (indicated with blue and brown arrows) and major tectonic features (MBT, Main Boundary Thrust of the Himalaya; ITS, Indus-Tsangpo Suture; BNS, Bangong-Nujiang Suture; JS: Jinsha Suture; ATF, Altyn Tagh Fault; HYF, Haiyuan Fault). b Simplified geological map of the Lanzhou and Xining basins with the West Qinling Fault (WQLF) and locations of sections (red solid circles) mentioned in the text.