Quantitative melting predictions under uncertain solidus conditions

Determine quantitatively whether the thermal anomaly generated by deformational heating during subduction initiation can reproduce the observed Lesser Antilles melting conditions when the initial geotherm and volatile-dependent mantle and crustal solidi are properly constrained.

Background

The model predicts only small amounts of partial melting at pressures and depths that differ from petrologic estimates for the Lesser Antilles. The discrepancy may result from an overly cold initial geotherm and from using an anhydrous solidus, whereas the actual solidus depends strongly on the poorly constrained volatile content of mantle and crustal rocks.

Consequently, the simulations do not yet establish quantitatively whether deformational heating alone can account for the observed melting conditions. Resolving the issue requires improved constraints on the initial thermal state and volatile-dependent melting relations.

References

The temperatures attained in our model after ${\sim}$6-7 mys are still less than those required by the data of \citeA{perrin2016reconciling}, but the location and shape of the additional thermal anomaly produced by deformational heating looks correctly situated compared with the conclusions of \citeA{perrin2016reconciling}. The small amount of partial melting in our model occurs at ${\sim}$100 km, beneath the Moho - clearly in the asthenosphere, and deeper than the above estimates - where pressures are more like ${\sim}$3-4 GPa. This discrepancy could partly be because our initial geotherm was too cold but also because we used the anhydrous solidus. Given the large uncertainty in solidus we cannot address this important question quantitatively as yet.

— 3-D numerical modelling of the feedback between deformation and thermal structure during subduction initiation for the French Lesser Antilles  (2608.19990 - Momoh et al., 20 Aug 2026) in Section “Discussion,” subsection “Arc establishment, High heat flow with small partial melt as a consequence of deformation”