Atmospheric significance of aeolian salts in the sandy deserts of northwestern China

Abstract

Large sandy deserts in the middle latitudes of northwestern China were investigated for soluble salt variations in modern and ancient aeolian sediments, aiming to explore the environmental significance of "aeolian salts". Results revealed that aeolian salt variations have a clear relationship with the changing meridional and zonal gradients of the desert locations and the aeolian differentiation effect, but are weakly linked to local geological conditions. Atmospheric depositions of water-soluble chemical species are an important process/source contributing to aeolian salt. Sequential variations of soluble salts in sedimentary profiles interbedded with aeolian and non-aeolian deposits and their palaeoenvironmental implications in the hinterland areas of these deserts were further evaluated, based on the constraints of OSL dating and radiocarbon dating data. The results indicate that inorganic salts may be a latent geoproxy in revealing regional palaeoclimatic changes in desert areas for sediments deposited under a single depositional environment, but the interpretation should be more cautious for sediments deposited under diverse depositional conditions. This study presents evidence of the atmospheric origin of aeolian salt in sandy deserts, with limited climatic significance in palaeoenvironmental reconstruction.