Multi-method dating of typical nebkha sediments in the Otindag dune field

The Otindag dune field, located on the Inner Mongolia Plateau and covers an area of approximately 52,000 km², ranks among the four largest dune fields in China. Located near the northern boundary of the East Asian monsoon, this region exhibits a cold temperate monsoon climate that transitions from semi-arid to arid conditions. The mean annual temperature ranges from 0 to 3 °C, while winter temperatures average approximately -18.3 °C, with an extreme minimum of -36.6 °C, reflecting the region’s significant seasonal thermal variation. In the southern Otindag dune field, nebkhas, a distinctive biogeomorphological aeolian landform created by the accumulation of sand around vegetation are distributed. The relatively thick sand layers within nebkha dunes are excellent sedimentary archives with great potential to capture past climate and environmental changes that occurred during the historical period and the Anthropocene. However, establishing a robust chronological framework for nebkha sediments remains a significant challenge due to limitations in existing dating methods.

In this study, we employed both luminescence and Cs-137 dating techniques to establish a chronology for nebkha sediments in the Otindag dune field. Luminescence dating results demonstrate that quartz luminescence signals from nebkhas are relatively strong and well-suited for age framework construction. The ages derived from the Central Age Model (CAM) and Minimum Age Model (MAM) are largely consistent, indicating effective bleaching of the quartz luminescence signals. Conversely, single-aliquot K-feldspar dating results exhibit a significant overestimation of ages. To address this discrepancy, we applied single-grain (SG) techniques in conjunction with the Minimum Age Model (MAM) to refine the dating of K-feldspar samples, yielding ages in agreement with quartz results. Cs-137 dating further validated the chronology, revealing that the primary development of nebkhas occurred within the past 100 years, which may be attributed to climate-driven or human-induced aridification in this region. Compared to other dune field regions in northern China, such as the Mu Us dune field, quartz from the Otindag dune field exhibits higher luminescence sensitivity, whereas K-feldspar signals display significant bleaching challenges. This study hypothesizes that regional variations in mineral luminescence properties may be attributed to differences in sediment provenance, which will be further investigated in future research. This study enhances the applicability of luminescence dating techniques for young nebkha sediments, providing a methodological framework for other nebkha fields across the globe.