Technical note: Kinetically resolved volatile and redox fingerprints of geologic materials by TGA/DSC-MicroGC

Abstract. The biogeochemical cycles of carbon, oxygen and sulfur are fundamental interlinked, yet quantifying their speciation and reactivity 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. This approach kinetically resolves and quantifies distinct carbon and sulfur species through their unique thermal decomposition profiles. Furthermore, continuous monitoring of oxygen consumption provides a direct measure of a material’s absolute redox capacity, yielding a kinetic fingerprint of its reducible components. Validation against geochemical standards and application to sediments from the Congo Basin and Lake Cadagno, reveal diagenetic transitions and paleoenvironmental fluxes that are invisible to conventional bulk methods. This integrated methodology provides a mechanistic, high-resolution view of electron-transfer processes in natural materials, providing a transformative tool for probing biogeochemical cycling, redox evolution and environmental reactivity across Earth systems.