Chronology of Holocene sediments from the archaeological Salawusu site in the Mu Us Desert in China and its palaeoenvironmental implications

The archaeological Salawusu site is located at the southeast margin of the Mu Us Desert, and in the northern marginal area of the East Asian Monsoon. Therefore, its environment is sensitive to the changes of the East Asian Monsoon. At the palaeolithic Salawusu site, most of the previous studies are concerned with the age of the palaeoanthropic fossils (ages ranging from 30 to 120 ka) and the climate change in the last glaciation period, while studies on the chronology and climate change since the Late Glacial are very limited. In the current study, eight luminescence samples were collected from Dishaogouwan (DSG) section and dated using quartz optically stimulated luminescence (OSL). Radiocarbon samples were also collected, and the past environmental changes since the Late Glacial have been reconstructed based on stratigraphical and chronological data. The results show that: (1) the AMS age of modern weed living under water is about 1550 ± 35 a, which is the current reservoir effect age, and after reservoir effect subtraction the radiocarbon age of the shells is in agreement with the OSL age, while the radiocarbon age of the bulk sample is younger; (2) aeolian sand mobilization occurred in the studied region before ∼12 ka; (3) within the Holocene, the wettest climate occurred during the onset of the Holocene when an extensive palaolake existed in the study area, marked by the development of lacustrine sediments at around ∼12 ka; (4) after ∼12 ka, the climate showed a trend of increasing aridity, which led to a continuous shrinkage of the palaolake, and its ultimate desiccation between 1.8 and 1.0 ka evidenced by the shift from lacustrine sediments to peat, and finally to palaeosol; (5) the dating results also show an enormous incision of about 60 m in about 1.75 ka by the Salawusu River.

► Comparison was made between OSL and 14C dating for Holocene lacustrine samples, and the 14C reservoir effect was assessed. ► Aeolian sand mobilization occurred in the studied region before ∼12 ka. ► Within the Holocene, the wettest climate occurred at the onset of the Holocene. ► After ∼12 ka, the climate showed a trend of increasing aridity leading to a continuous shrinkage of the palaolake. ► The Salawusu River has an enormous incision of about 60 m in the last ∼1.75 ka.