Characterization of lamp oil residues from Tangchaodun Site, Xinjiang, northwest China during the 8th−13th centuries CE

Abstract

Lamp illuminants reflect how ancient people exploited natural resources, such as animal fat, plant oil and mineral oil. Besides, the commercial trade of lamp oil, including olive oil, represented economic exchange. In addition, oil lamps were often used in religious practices to glorify deities and illuminate grand halls. Although many ancient lamps have been found in China, there are few scientific reports regarding ancient lamp illuminants. In this study, chemical analysis including FTIR (Fourier Transform Infrared Spectroscopy), Py-GC/MS (Pyrolysis Gas Chromatography-Mass Spectrometry), GC–MS (Gas Chromatography-Mass Spectrometry), and GC-C-IRMS (Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry) was applied to characterize black residues remaining on the surface of pottery lamps from the Tangchaodun site, northwest China, from the 8th to 13th centuries CE. The results show that the black residues are soot, and both ruminant adipose fat and plant oil were used as the primary fuel. These lamps share similar morphology and utilize similar combustibles, implying that the production of both lamps and oil may have undergone convergent evolution driven by aesthetic preferences. Furthermore, the ruminant animals mainly fed on C4 plants, indicating that these animals were raised in pens and millet agriculture was practiced in this region.