Increased winter-spring precipitation from the last glaciation to the Holocene inferred from a 13Corg record from Yili Basin (Xinjiang, NW China)

The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover, most of the published studies focus mainly on the evolution of moisture conditions, and there have been few attempts to address changes in seasonality. In this study, records of C-13(org), TOC, TN, C/N and grain size were obtained from lacustrine sediments at Yili Basin, Xinjiang, NW China. Our aim was to reconstruct the trend in seasonality of precipitation from the last glaciation to the Holocene. The organic matter content of the sediments is derived predominantly from terrestrial plants. The C-13(org) values vary from -19.4% to -24.8%, indicating that the vegetation was dominated by C-3 plants. Winter-spring precipitation is identified as the factor determining the relative proportions of C-3 and C-4 plants in the region. A negative trend in C-13(org) corresponding to an increase in the relative abundance of C-3 plants indicate a trend of increasing winter-spring precipitation from the last glaciation to the Holocene. The increased incidence of wintertime storms in the interior of Asia is suggested to result in the increase of winterspring precipitation in the Holocene.