Comment on “Pressure-to-Depth Conversion Models for Metamorphic Rocks:
Derivation and Applications”
Abstract
Bauville and Yamato (2021, G-cubed,
https://doi.org/10.1029/2020GC009280) propose model-based methods to
convert metamorphic pressures to depths based on the claim that pressure
data from global (ultra)high-pressure rocks challenge the lithostatic
assumption and support their model which invokes excessive
overpressures. It is argued here that the opposite is true: Natural
pressure data are fully consistent with the lithostatic assumption. They
reflect selection of (ultra)high-pressure rocks by accessibility and
preservation. The data are however inconsistent with the model
predictions of Yamato and Brun (2017, Nature Geoscience 10, 46-50) and
Bauville and Yamato (2021). Furthermore, their model requires critical
assumptions that are not justified by the principles of rock mechanics
and unsupported by microstructures from (U)HP rocks.