Significance of H2 and CO release during thermal treatment of natural phyllosilicate-rich rocks

Phyllosilicates may trap hydrogen (H2) in the crust, but they also produce it through various processes, including oxidative dehydrogenation. The dehydrogenation temperature depends on type and composition of phyllosilicates considered, be as low 300 °C. Here, we document release H2 CO during thermal treatment chloritite (300 °C) talc (500 from Trimouns deposits (Eastern Pyrenees, France). Thermal gases coupled to stable isotope analysis has been used recover characterize CO, two detected gases. Hydrogen content high 7 ppm with δDH2 values ranging −258‰ – 224‰ for sub-pure − 140‰ pure talc. ranges between 3 35.3 very homogeneous δ13CCO −27.6‰ 25.7‰. This study supports idea that was produced experiments by origin remains enigmatic, its carbon suggests a link few amounts graphite documented deposit. work reports extensive fractionation both chloritite. Dehydrogenation is potential source term numerous magmatic-hydrothermal settings must thus accounted budget geochemical cycle.