Metamorphic evidence of rapid heat production during geological information

The advent of inverse diffusion modelling in minerals has allowed the quantification of effective timescales and cooling rates of metamorphic assemblages. Such information can be proven very useful if combined with information from conventional thermobarometry. This is because, cooling rates at various geologic conditions can provide essential constraints on the temporal character of geodynamic models. Constraining the temporal character of metamorphic processes from natural data provides us with non-unique solutions because of the nature of the data examined. However, considering additional constraints from geophysical/geodynamic models helps reducing the uncertainty of the results since it allows the incorporation of additional (and independent) constraints. Additional constraints include, but are not limited to, erosion rates, maximum topography and maximum surface heat flux.

In this work I present a systematic study from thermo-kinematic and thermo-mechanical models that aims in identifying the key parameters responsible for the preservation of steep compositional gradients in minerals. Results show that in active tectonic environments, fast advection is essential for the rapid transient cooling of metamorphic assemblages. However, for the same type of data, less extreme velocity values can be used if the effects of dissipative heating are included. Therefore, apart from the thermodynamic consistency, the consideration of dissipative heating during geological deformation allows the use of more realistic parameters in geodynamic models.