A Comparative Study of 14C Dating on Charcoal and Charred Seeds from Late Neolithic and Bronze Age Sites in Gansu and Qinghai Provinces, NW China

Abstract

The chronology of the Neolithic and Bronze Age cultures in Gansu and Qinghai provinces, northwest China, is mainly based on conventional radiocarbon dates from unidentified charcoal, which may be inaccurate in view of the possible “old wood” problem of 14C dating. To discuss the reliability of the chronology of those prehistoric cultures, accelerator mass spectrometry (AMS) dates of short-lived charred seeds were compared to conventional 14C dates of unidentified charcoal from the same flotation samples in 15 Late Neolithic and Bronze Age sites in the area. The results show that 14C dates of unidentified charcoal are obviously older than those of charred seeds in 5 of the 15 flotation samples. This work suggests that the old-wood problem of 14C dating might be related to human subsistence strategies and local vegetation variation during different prehistoric cultural periods in Gansu and Qinghai provinces, which should be discussed before establishing the chronology of Neolithic and Bronze Age cultures in the area.