Provenance of eolian sands in the Ulan Buh Desert, northwestern China, revealed by heavy mineral assemblages

摘要

Accurate identification of the provenance of eolian sand in deserts is essential to study sedimentation processes in the earth system. Exposed bedrock surrounding the desert has been regarded as the main source of eolian sand in some deserts of the world. However, few studies have focused on whether paleolacustrine deposits and bedrock outcrops in desert hinterlands are the main sources of eolian sand. In this study, we selected the Ulan Buh Desert in northwestern China as the study area, and a total of 99 samples were collected throughout the desert and nearby regions to study the provenance of the current eolian sand based on their heavy mineral assemblages and contents. The results showed similar heavy mineral assemblages among the eolian sand, the bedrock to the northwest of the desert, and the paleolacustrine deposits and exposed bedrock in the desert hinterlands, suggesting multiple provenance for the eolian sand in the Ulan Buh Desert. The sources of the eolian sand in the Ulan Buh Desert include bedrock to the northwest, gobi to the west, and paleolacustrine deposits and exposed bedrock in the desert hinterlands. Helan Mountains bedrock and Yellow River fluvial deposits near the desert contribute little to the eolian sand. Moreover, the paleolacustrine deposits and exposed bedrock in the desert hinterlands should not be neglected as the potential provenance of eolian sand in other studies. This study enhances understanding the provenance of eolian sand in the deserts of northern China.