Raman spectroscopy and structural heterogeneity of carbonaceous material in Proterozoic organic-walled microfossils in the North China Craton

•We report the structural characteristics of Proterozoic organic-walled microfossils using Raman spectroscopy in North China.•CM in Ruyang and Liulaobei microfossils experienced low-grade metamorphism with apparent peak metamorphic temperatures of ~200 °C.•Heterogeneities in structural characteristics exist among different subcellular structures of S. macroreticulatum and different taxa of the same stratigraphic horizon.