Sand provenance in the Gurbantunggut Desert, northern China

Abstract

The provenance of desert sands controls the formation and development of sand seas. However, the sediment provenance in the Gurbantunggut Desert, the second-largest desert in China, has been largely unknown. We collected samples from sand dune crests and nearby interdune lacustrine deposits in the desert’s core regions, as well as from the beds of rivers originating in the surrounding mountains, and analyzed samples for rare earth elements and trace elements. The novelty of our research was to apply geochemistry properties of samples to explain how fluvial and aeolian system controlled aeolian sediment transport and reworking processes. In order to identify the sand provenance, we first calculated fingerprint indexes based on range tests for a variety of parameters, and applied multidimensional scaling to establish the similarities among samples. Range test indicated that Cu, Zn, As, Rb, Nb, Mo, In, Sn, Ls, Ce, Ta, Y/Nb, Sc/Y, Y/Nd, Sc/La, ΣREE, Lan, and LREE can be used as the fingerprints indices. The elemental geochemical characteristics of samples were similar among Altain Mountains, and different with samples in the desert. However, elemental compositions were similar between Tianshan Mountains and Junggar Mountain and in the desert. We found that clastic materials from the Junggar Mountains and Tianshan Mountains were carried to low-lying areas of the Gurbantunggut Desert by rivers, whereas the areas with relatively high topography located along on the route blocked flowing water, and transport was instead by strong westerly winds and arrived by means of aeolian transport. The parent materials from surrounding mountains, river fluxes, and topographic elevation determined the proportions of sand from different sources, which varied among sites in the desert. Clastic material from the Altai Mountains could not be transported to the Gurbantunggut Desert because it was blocked by an elevated river terrace.