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Abstract:
The timescales of magmatic processes such as, mixing, fractionation, and intrusion can be determined with diffusion chronometry via modeling the elemental or isotopic concentration gradients in minerals and/or glass. These time scales are very relevant for understanding the processes and durations that occurs below active volcanoes and have been linked to time series of monitoring data for better anticipation of volcanic eruptions. However, the obtained timescales heavily depend on the value of the diffusion coefficient, which in turn, strongly depends on the chosen magmatic temperature. Given the difficulty to uniquely constrain the relevant temperature for the process at hand, and the significant size of the errors of commonly used geothermometers, the choice and error of temperature introduces a significant uncertainty on the calculated timescales. This hamper making a robust link between the inferred magmatic processes at depth, with the time series of monitoring data measured at the surface. Here we show that by modeling multiple elements with different activation energies in a single crystal, it is possible to simultaneously constrain the temperature and timescale in a robust manner. Inversion of multiple element compositional profiles of many crystals, and eventually different minerals, should lead to much more robust estimated of the timescales and thermal history of magmatic processes.
