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Identifying the provenance of aeolian sediments in deserts is of great importance for understanding the Earth surface processes. In this context, we conducted detailed fieldwork in the Ordos Deserts (Maowusu and Kubuqi) in the middle portion of the desert belt in northern China, and measured the major, trace and rare earth elements (REE) of aeolian sands and their potential source rocks and sediments. Our results show that aeolian sands in the eastern (northeastern) and western (southwestern) Maowusu (Mu Us) Sandy Land exhibit different degrees of mineralogical maturity and Eu/Eu* values. Thus, we interpret that these aeolian sands have different provenances, though in the same sandy land. Our data suggest that the local lacustrine sediments and sandstones are the main sources of aeolian sands in the eastern province of the Maowusu Sandy Land, while aeolian sands in the western Maowusu Sandy Land and the Kubuqi Desert have the same external sources. The comparison of geochemical compositions of sediments in the Ordos Deserts with their potential sources in adjacent regions indicates that there is no genetic linkage between the Helan Mountains, the Yinshan Mountains and the Ordos Deserts although they are not far apart. The Qilian Orogenic Belt in the northeastern margin of the Tibetan Plateau is, however, the most likely original provenance for the western Maowusu (Mu Us) Sandy Land and the Kubuqi (Hobq) Desert, but with fluvial sediments in the Ningxia-Inner Mongolian section of the Yellow River as the immediate source. In one side, our results demonstrate that dune fields that are close to each other can have significantly different source sediments. On the other hand, our work suggests that some dune fields and landforms that are far apart from one another, e.g., the Badain Jaran Desert in western Inner Mongolia, the Ordos Deserts and the fluvial sediments in Ningxia-Inner Mongolian section of the Yellow River, can share the same ultimate sources. [ABSTRACT FROM AUTHOR]

In environmentally sensitive areas, particularly the arid or semi-arid regions, different factors such as relief and human activity, can greatly influence the landscape on a local scale. Using satellite imageries and field investigations, we have studied the distribution of sand dunes in the Maowusu (Mu Us) Sandy Land in the southern Ordos Plateau, northern China. Key research questions are which factors are critically responsible for the spatial pattern evident in the landscape and what is the relative importance of such factors? We used a new approach, i.e., the Geographical Detector to improve our spatial analysis. Using the combined methods of the Geographical Detector, digital image processing, field investigation and spatial and temporal analysis of the Normalized Difference Vegetation Index (NDVI), we aimed to clarify the causal relations governing the different landform patterns within this Sandy Land and beyond. The primary factors include local relief, drainage, climatically controlled potential plant productivity, wind action and rock type as explanatory parameters x and the landscape properties as the output y . Our results show the quantified links between the spatial distribution of various landscapes and their controlling factors. This study revealed that the climatic potential productivity, local relief and drainage are the key factors in shaping the landscape spatial pattern. Owing to different regional climates and land use histories, the responses to changes of external forcing between the western and eastern parts of the Maowusu Sandy Land are out-of-step. We conclude that the desertification of the eastern part of Maowusu Sandy Land has been mainly caused by human activities while the western part is governed by natural factors. [ABSTRACT FROM AUTHOR]