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The Hobq Desert (HD) locates at the northern margin of the Ordos Plateau, China and the transition zone to the Hetao Basin. It is one of the main proximal deserts of the Loess Plateau, and its formation was controlled by the evolution of the Yellow River and the Ordos Plateau. It is still worthy of discussing the regional structure to enhance the understanding of the desert formation and paleoenvironment, especially with the additional works in the eastern part. Geophysical methods including gravity, magnetic, EM (electromagnetic) are often used to analyse the regional and near-surface structure. As for drilling records, they could show the lithology sequence directly and be applied for the environmental study (e.g., OSL dating). Therefore, in this paper, we used the satellite gravity data, GPR (Ground Penetrating Radar), TEM (Transient electromagnetic method) and drilling records with borehole resistivity data to analyse the desert structure from different scales and the paleoenvironment. Trough the upward continuation and Park-Oldenburg calculation for the gravity data, the thickness of Quaternary deposits is 0.85–1.55 km. The inferred faults indicated the performance of the Hetao Basin and the Ordos Plateau's uplift in Pleistocene, which also contributed to HD's formation and existing topography. A three-part structure within 350 m was revealed in the profile at eastern HD by EM data. The upper layer within 80–90 m was the aeolian dry sand, the middle one was mainly fluviolacustrine saturated sand with the occurrence of clay and grey calcareous root tubes, and the lower one might be the aeolian sand. This near-surface structure was consistent to the western part, and the forming period for the sand in the upper zone was thereby estimated no earlier than 80 Ka. Moreover, during this period, millennial-scale changes in paleo-effective moisture occurred although it was dominated by the arid climate. [ABSTRACT FROM AUTHOR]

As a part of the INQUA project “A Global Digital Database and Atlas of Quaternary Dune Field and Sand Seas”, 337 age records from the desert dunes of China and 20 from Mongolian dune fields have been compiled in the database. This has opened the possibility of exploring and synthesizing the Quaternary environmental changes in the Asian mid-latitudes dune fields directly from the on-site aeolian sand archives. This paper assessed the sand dune chronologies in terms of geographical distribution, data quality and their implications for late Quaternary palaeoenvironmental reconstructions. The available ages are concentrated mainly in the last 20 ka and many are from the fields of stabilized dunes in the eastern portion of the desert belt in northern China. The number of records and the ratio between the records of stable state and the total records could act as a proxy for the palaeoenvironmental interpretation. The aeolian sand activities deciphered from the chronological data in the eastern portion of the desert belt in northern China show a reasonable correlation with the general global climatic curves at the glacial–interglacial timescales. The limited aeolian sand records from the glacial period, however, hamper the understanding of the detailed features (e.g., forms and processes) of the dune fields during glacial times. In the last two millennia, however, there has not been any meaningful correlation between aeolian dune activity and climatic variation at the centennial time scales, probably due to the complexity of the aeolian sand systems and human interventions. Extending the coverage of dune chronology both temporally and spatially is urgently needed for a full understanding of the environmental changes in the dune fields. [ABSTRACT FROM AUTHOR]