The cycling of rocks between the Earth's surface and interior affects everything from the evolution of the crust and mantle to the composition of the atmosphere. To quantify the processes occurring during subduction and exhumation of rocks, geoscientists utilize a broad range of tools, one of the most important of which is the distribution of stable isotopes. The fractionation of stable isotopes of carbon changes significantly with temperature. The carbon isotope distribution between calcite and graphite is particularly important because it has the potential to provide temperature information about metamorphic processes. Recent developments in secondary ion mass spectrometry have lead to new insights into graphite precipitation during metamorphism and hold promise to advance our understanding of the temperatures and rates of metamorphic processes. However, these interpretations rely on graphite growth data that has been extrapolated over significant temperature and pressure ranges, as well as empirically calibrated fractionation relationships that have not been experimentally verified. This work will provide direct experimental measurements of these factors, and will help understand the cycling process within the Earth.
