No evidence for an anti-phased Holocene moisture regime in mountains and basins in Central Asian: Records from Ili loess, Xinjiang

Arid Central Asia (ACA) is far from oceanic moisture sources and has a prevailing arid climate; thus the environment of the region is hydroclimatically sensitive. The eastern part of ACA is dominated by the basin-mountain system. A previous study proposed that the humid mountains and the arid basins were characterized by an opposite pattern of climatic variation during the Holocene, with a long-term drying trend in the former and a wetting trend in the latter. However, robust evidence from an integrated basin-mountain system using the same geological archive is urgently needed to test this hypothesis. Here we present Holocene paleoclimatic results from two new loess sections, with reliable chronologies, from Tienshan Mountain slope. In combination with two additional loess records from the intermontane arid basin, a systematic mountain-basin comparison was carried out. The results indicate that a Holocene paleosol started to develop on the Tienshan Mountain slope (at an elevation of 1300-1600 m) during 7-5 ka, which is broadly synchronous with paleosol development in the arid basin (at an elevation of 500-800 m). Furthermore, magnetic-parameter-based precipitation reconstructions from the four loess sections all demonstrate a consistent wetting trend throughout the Holocene. Therefore, our findings do not support an anti-phased pattern of moisture/precipitation change between the humid mountains and the arid basins in eastern ACA.

Automated summary

This study reveals a consistent wetting trend throughout the Holocene in arid Central Asia, based on analysis of two loess sections from Tienshan Mountain slope and two additional loess records from the intermontane arid basin. This finding contradicts the hypothesis of an anti-phased pattern of moisture/precipitation change between the humid mountains and the arid basins in the region.