A petrological analysis of petrified wood from Lesvos Island (Greece) and Yanqing (China) Geoparks: implications for sample conservation

Classifications and comparisons of petrified wood are currently based primarily on observable morphologies. The mineralogical characteristics of specimens collected from Qian Jiandian, Yanqing UNESCO Global Geopark, Beijing, China and Sigri, Lesvos Island UNESCO Global Geopark, Greece, were compared in this study to enhance the conservation and protection of Chinese petrified wood. Comparisons were carried out on the basis of internal structural observations using a polarising microscope, x-ray diffraction (XRD), and analysis of major and trace elements. Results show that structures and main chemical components (SiO2) remained almost the same between samples while organic carbon and numerous trace elements (e.g. As, Cu, Mo, Zn) were significantly different. The approaches employed at Lesvos will require modifications in future work, including adjusting adhesives and solvents for different climates, selecting conservation sites and methods based on different preservation conditions, and determining appropriate cleaning methods and agents according to different petrified wood components. The results of this analysis lay the theoretical foundation for petrified wood conservation in Yanqing. Work at this site is the first model study for the preservation of petrified wood in China and creates new opportunities for related research.