Program > Browse abstracts by speaker > Delarue Camille

Carbonaceous organic matter (COM) undergoes transformation under pressure and temperature, losing heteroatoms and reorganizing its carbon structure into graphite-like sheets. This process results in a density evolution from approximately 1300 kg/m³ at ambient conditions to around 2300 kg/m³ at 1300 K. Understanding the kinetics of this transformation is essential for various geological and planetary applications. To characterize this transformation, experimental studies were conducted at pressures up to 7 GPa and temperatures up to 723 K. Diamond anvil cell (DAC) experiments were used to assess the volume compression of COM as a function of pressure. Additionally, thermal effects were investigated using experimental samples heated between 473 and 723 K for durations ranging from seconds to hundreds of days under pressures between 0.2 and 2.5 GPa. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX) was used to determine the oxygen-to-carbon ratio of these samples. The results of these kinetic experiments allowed to adjust parameters of the Vitrimat kinetic model to model compositions close to type III kerogens at high-pressure conditions. The new model predicts the nature and proportions of released volatiles (H₂O, CO₂, and CH₄) for a given initial COM composition as a function of time and temperature. The model successfully predicts data from various literature sources, ranging from kerogen to meteoritic insoluble organic matter (IOM). Results from the compressibility and kinetic evolution of COM enabled the formulation of an equation describing the density evolution of OM as a function temperature and pressure. This equation has broad applicability, extending from the metamorphism of Earth's coals to the transformation of IOM in dark asteroids, comets, and chondrites, which are considered precursors of outer solar system bodies. Applications to icy bodies will be presented.