Testing micro-aliquot SGC and LnTn methods for age determination up to 780 ka using coarse K-feldspar grains from Nihewan Basin, northern China

Abstract

The Nihewan Basin in northern China is a key region for the study of Paleolithic archaeology of East Asia, due to the discovery of Paleolithic sites with ages spanning the entire Pleistocene. However, many Paleolithic sites assigned to the Middle to Late Pleistocene are still not dated or poorly dated, which affects our understanding the stone tool technology evolution in the Nihewan Basin. The post-infrared infrared stimulated luminescence (pIRIR) signal from potassium-rich feldspar grains can be applied to date Middle to Late Pleistocene sediments, as this signal has significantly lower fading rate. In this study, to establish a robust chronological framework of the Nihewan Paleolithic sites more effectively, a micro-aliquot (MA) standardised growth curve (SGC) was constructed for pIRIR dating. The established MA SGC was tested for sediments up to 780 ka, and the obtained MA SGC D_e results were compared with those from single-aliquot (SA) measurement. Results from a number of tests suggest that the disagreement between MA and SA results is due to a small amount of anomalous fading in dimmer grains, which can be corrected by T_n threshold. By projecting the weighted mean L_n/T_n ratios (after T_n threshold correction) onto the MA SGC, the obtained pIRIR ages increase from top to bottom, and the sample from just above the B/M boundary (∼780 ka) yielded an age of ${725}_{-117}^{+179}$ ka, which is consistent with the expected age. Our result suggested that the MA SGC method can reduce instrument time and has the potential to provide reliable age up to ∼700–800 ka in this region.