Technical note: Kinetically resolved volatile and redox fingerprints of geologic materials by ramped combustion microchromatography

Abstract

The biogeochemical cycles of carbon, oxygen and sulfur are fundamentally interlinked, yet quantifying the reactivity of these elements within complex geological matrices remains a major analytical challenge. We present a novel integrated TGA/DSC-MicroGC system that simultaneously monitors mass loss, heat flow, and evolved gas composition during controlled heating in a gas mixing furnace. This approach kinetically resolves and quantifies distinct carbon and sulfur materials through their thermal decomposition profiles. Furthermore, continuous monitoring of oxygen consumption provides a direct measure of a material’s oxidability in various temperature windows, a redox fingerprint. Validation against geochemical standards and application to sediments from the Congo Basin and Alpine Lake Cadagno (Switzerland) reveal diagenetic transitions and paleoenvironmental fluxes that are invisible to conventional bulk methods. This integrated methodology provides a mechanistic, high-resolution insight into electron-transfer processes in natural materials. This offers new avenues for probing biogeochemical cycling, redox evolution and environmental reactivity across Earth systems.