资源环境科技发展态势分析平台

It is generally agreed that the aeolian loess on the Chinese Loess Plateau (CLP) is derived from adjacent upwind arid areas, mainly including the Qaidam Desert, Alxa arid area, and Ordos Desert. However, the mineralogical and geochemical compositions of aeolian materials show several inconsistencies between these adjacent source areas and the CLP. Here, we compare the distribution of carbonate minerals in bulk samples and the <63-mu m fraction from upwind deserts to six loess sections from the CLP. The results show that the detrital dolomite and total carbonate, which are abundant in the loess of the CLP, are concentrated in the Taklimakan Desert rather than adjacent source areas. This finding suggests that the distant Taklimakan Desert is an important source of aeolian deposits on the CLP, reconciling the mineralogical and geochemical inconsistencies between CLP and adjacent areas.

Plain Language Summary The Taklimakan Desert is the largest source of dust emissions in central Asia. It has not been considered as a source area of aeolian deposits on the distant downwind Chinese Loess Plateau (CLP) in past geological periods due to its semiclosed topography, although their geochemical and mineralogical compositions are similar. The dust material on the CLP has been identified as derived from adjacent upwind arid areas in recent studies. Here, we investigate the distribution of carbonate minerals from potential source areas across a large area and the loess deposits on the CLP. The results show that in bulk samples, carbonate mainly appears in the Taklimakan Desert, depending on the surrounding bedrock types. In the Alxa arid area, only dolomite exists, and carbonate is obviously concentrated in the <63-mu m fraction, possibly influenced by wind transport from the upwind Taklimakan Desert and adjacent areas. Comparing the dolomite and total carbonate distributions between deserts and loess, we find that their initial contents in the loess are slightly lower than those in the <63-mu m fraction of the Taklimakan Desert. These results demonstrate that the distant Taklimakan Desert is necessarily a source of the CLP.