• Hydrological indications of aeolian salts in mid-latitude deserts of northwestern China

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      https://www.ias.ac.in/article/fulltext/jess/125/04/0809-0820

    • Keywords

       

      Aeolian salt; sequence salinity; hydrological indications; environmental geoproxy; earth surface processes; middle-latitude desert

    • Abstract

       

      Large sandy deserts in middle latitude of northwestern China were studied on salt variations in modernand ancient aeolian sediments, aiming to explore their hydrological indications at the present and past.Globally, sulphate is rich in arid to semi-arid deserts, including the aeolian loess sediments in China andsoils in low-latitude deserts, but is less common in the aeolian sediments from the mid-latitude desertsin this study. The compositional differences between aeolian salts and local natural waters is evident,indicating the chemistry of aeolian salts and the associated parent brines may be significantly differentthan that predicted for hydrologically closed systems. The formation of aeolian salts in the studieddeserts is strongly controlled by earth surface processes in a large scale but not in a local scale. Verticalchanges in facies and salinities are abrupt in the studied palaeo-aeolian sediment samples, which wereinterbedded by lacustrine/fluvial sediments with OSL and ^{14}C ages ranging between 40 and 2 ka BP,reflecting rapid high-amplitude changes in hydrological settings during late Pleistocene to later Holocenein these ancient playa systems. A great difference in salt composition between aeolian and lacustrinesediments suggests that the inorganic salt is a latent geoproxy in revealing local hydrological variationsand climate change in the desert areas. But the environmental indications could be amphibolous for thesedimentary sequences with dual/multiple depositional end-members; under this situation an increase insequence salinity does not always represent an enhanced environmental aridity. Ancient playas are aridor humid at the same time based on several sporadic records is not a valid approach to correlation of saltdeposits in adjacent saline playa basin in the studied areas. Effects of earth surface processes includingerosion, deposition and other processes on sediment properties will bias the hydrological implications ofsediment salinity.

    • Author Affiliations

       

      Bing-Qi Zhu1

      1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
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  • Journal of Earth System Science | News

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