TT-OSL and post-IR IRSL dating of the Dali Man site in central China

Showing features associated with archaic Homo sapiens and evolved Homo erectus, the Dali skull is a key fossil for understanding human evolution in China. Various dating methods such as U-series, IRSL, TL, ESR, ESR/U-series, and stratigraphical correlation with central Loess Plateau sequence were used to estimate the antiquity the Dali Man site with varying results. In this study, a total of 12 samples were taken in the sequence in the Dali Man site, from the aeolian loess-palaeosol sequence and underlying fluvial deposit layers including the palaeoanthropological level and dated by several optically stimulated luminescence (OSL) methods: coarse-grained quartz SAR OSL, thermally transferred OSL (TT-OSL), and K-feldspar post-IR infrared (IR) stimulated luminescence (post-IR IRSL; pIRIR290) methods. Results show that the TT-OSL and pIRIR290 ages were consistent up to ∼100 ka. For older samples, the feldspar ages were significantly older. These pIRIR290 ages increased with the stratigraphy up to 310 ka. The best age estimation of the Dali Man layer providing by the feldspar pIRIR290 suggested that the Dali Man lived in late period of L3 (MIS 8) stage. Furthermore, correlating the pIRIR290 ages between 267.7 ± 13.9 ka and 258.3 ± 14.2 ka and new pollen analysis, we proposed a new viewpoint that the Dali Man was likely to live during a transitional period from glacial to interglacial climate in the S2/L3 (MIS 7/8) stage.