Recently, a PhD student Yang He, under the guidance of Professor Li Guoqiang, the Key Laboratory of Western China's Environmental System, Ministry of Education, College of Earth and Environmental Sciences, Lanzhou University, published a paper entitled "Loess depositional dynamics and paleoclimatic changes in the Yili Basin, Central Asia, over the past 250 ka" in the top international journal Catena (Q1, Top journal).The research was funded by the second scientific investigation of the Qinghai-Tibet Plateau and the National Natural Science Foundation of China. Yang He, a PhD student of 2018 majoring in Physical Geography of the College of Earth and Environmental Sciences, is the first author of the paper and Professor Li Guoqiang is the corresponding author.
Xinjiang is part of the arid region of Central Asia and one of the most important dust source areas in the northern hemisphere. A large amount of Fe3+ carried by the dust released in this area provides nourishment for the growth of ocean plankton. Dust regulates the concentration of atmospheric CO2 by affecting the primary productivity of marine organisms, and various feedback mechanisms caused by it affect the energy balance of the earth system. Therefore, studying climate change in Xinjiang since the Quaternary is of great significance for understanding the environmental evolution in the arid area of Central Asia, the release of dust in the northern hemisphere, and the global continental climate change mechanism.
The study conducted high-density luminescence dating and a variety of paleoclimate proxy indicators (magnetic susceptibility, chroma, carbonate, and grain size) on the paleosoil sequence of the loess in the Yili Basin, clarified the loess deposition time, deposition pattern and driving mechanism, and reconstructed the regional Quaternary climate and environmental changes (Fig. 1).The study found that the Yili Basin began to accumulate loess as early as 350,000 years ago, but the sedimentary discontinuity occurred frequently. The loess accumulated rapidly during the last interglacial period from 93,000 to 75,000 years ago, and the river floodplain was caused by the downward cutting of the river during the transition period from the glacial period to the interglacial period. Dew provides a sufficient source of loess deposits and is a possible reason for the rapid accumulation of loess during the last interglacial period in this area. The loess deposition rate at different locations in the foothills of the same research site is significantly different, indicating that the loess accumulation in this area is affected by climate change, geomorphic environment, wind intensity and provenance changes, and the loess deposition process is not solely controlled by regional climate change.
Lanzhou University is the first institution to complete the research results. Scholars from the University of Queensland, Gansu Desert Control Research Institute, and Nantong University participated in part of the research.
Paper link:https://www.sciencedirect.com/science/article/pii/S0341816220304318
Fig1. Precipitation changes in the Yili Basin in the past 350,000 years
