The age of formation of the mirabilite and sand wedges in the Hexi Corridor and their paleoclimatic interpretation

The Hexi Corridor is located at the transition zone of the Asian summer monsoon and westerly airflow, and lies in an important position in terms of its ecological fragility and climatic sensitivity. During a recent field expedition to this region, we found a sedimentary mirabilite layer in a number of localities including Suwushan, Yanchi, Baitujing, Yanchi Gaotai, Huahai, Yumen, Halanuo扙r, and Dunhuang (Fig. 1), which have the potential to provide important information about environmenta…

The age of formation of the mirabilite and sand wedges in the Hexi Corridor and their paleoclimatic interpretation

Sand wedges in the Hexi Corridor mainly formed in an alluvial gravel stratum of the late Pleistocene and the radiocarbon ages of the eolian sand infilling wedge prove that they were a product of the last ice age. During their period of formation, the mean annual air temperature in the Hexi Corridor was about −5.3°C., i.e. about 13°C lower than that of the present. This estimated value is coincident with the decrease in air temperature predicated from mirabilite (Na₂SO₄ · 10H₂O) sedimentary layer in study area, and also agrees with research on the estimated amplitude of air temperature lowering in middle and high latitudes of the Northern Hemisphere during the last glacial period. The annual precipitation in the Western Hexi Corridor at that time was probably about 100–200 mm, i.e. about 100 mm more than at present.