European Palaeobotany and Palynology Conference 2026

Silica sinters deposited by hot-spring activity form Lagerstätten with abundant three-dimensional, cell-preserved fossils, as exemplified by the Rhynie chert. Palaeoecological interpretations of fossil sinters have drawn on modern large-scale geothermal provinces to infer their environmental settings and formation processes. Well-documented modern examples of silica sinters recording persistent terrestrial vegetation around hot-spring systems remain limited. Here, we present a new depositional facies model of silica sinter from a forested island-arc setting in Japan. We describe the preservation of present-day forest vegetation that coexists with ongoing sinter deposition. At Nakabusa Hot Springs in central Japan, thermal waters gently emerge from numerous small seeps on densely forested slopes. The thermal waters flow down through narrow channels with little disturbance to the forests, forming silica sinters. Solar-driven evaporation promotes silica precipitation and sinter growth. These sinters are subdivided into four depositional facies characterised by the incorporation of abundant modern plants from the surrounding forests, together with temperature-specific microbes. The forested hot-spring setting may serve as a valuable modern analogue for understanding the formation processes of plant-rich fossil sinters. The model provides a broader basis for palaeoecological interpretations of silica sinter Lagerstätten throughout the geological record.