Graphitic (sp2-bonded) carbons are widely present on Earth and in the Universe. They have a complex structural organization ranging from amorphous-like and turbostratic phases to perfectly crystallized graphite. This structure is a legacy of their geological history and is a fingerprint of the physico-chemical conditions that prevailed during their formation. To retrieve complete information, this structure must be characterized from the nm to the µm scale by combining various microscopy (SEM, TEM, STXM…) and spectroscopy (Raman, XANES), together with isotopic geochemistry. Various recent studies involving graphitic carbons will be reviewed such as fossilization and traces of life in high-pressure metamorphic rocks, graphitization during metamorphism (which can serve as a geothermometer), or abiotic graphite formation from carbonate reduction during fluid-rock interactions in subduction. Last, the fate of graphitic carbons during erosion will be discussed as they might be recycled owing to their refractory character, and therefore constitute a carbon sink on geological timescales.
Discipline Categories: Mineralogy/Crystallography, GeochemistryPreferred Presentation Type: Oral