Early metal exploitation and bronze casting in the Xiang River basin: evidence from the Zhongjiawan site in Hunan, China

Abstract

In 2016, several important metallurgical relics were found during an excavation at the Zhongjiawan site of the Tanheli city site in Hunan Province, China. According to the radiocarbon dating results and pottery typology analysis, the age of Zhongjiawan site was mainly occupied ca. 12th − 10th century BC, range from the late Shang to the early Western Zhou period. The metallurgical relics from the Zhongjiawan site were analysed using a metallographic microscope, energy dispersive X-ray fluorescence spectrometer, and multi-channel receiver inductively coupled plasma mass spectrometer. The results reveal that their materials included copper, tin bronze, leaded copper, and lead-tin bronze. All were cast and formed without leaving any processing marks. The analysis of crucible fragments and metal fragments suggests that local casting activities may have occurred at the Tanheli city. In order to conduct in-depth research on the source of bronze ore materials in the region, 26 bronzes from the Tanheli and Gaoshaji sites were analysed using portable energy dispersive X-ray fluorescence spectrometer, and combined with their detected lead isotope data. Comparative analysis of lead isotopes indicates that the lead material in Zhongjiawan was possibly quarried from lead-zinc mines in Hunan and southeastern Hubei, while the copper material more likely originated from copper mines in the middle and lower reaches of the Yangtze River. The results clarify casting technology and metal provenance, providing the key evidence for localized production of Zhongjiawan site and bronze culture interaction in the Xiang River Basin and southern China during the Early Bronze Age.