Observational constraints on source-region sizes for planetary volcanism

Determine the characteristic spatial sizes of partially molten source regions associated with volcanic activity on Mars and other terrestrial planets to assess whether the magmatism–mantle upwelling feedback (MMUb) operates. Constrain these sizes sufficiently to evaluate the prediction that Large Igneous Provinces (LIPs) correspond to source regions exceeding a critical spatial scale, whereas hotspot volcanism may not, thereby testing the scale-dependent threshold for MMUb-driven mantle flow and melt migration.

Background

The paper develops a framework showing two regimes for magma ascent in partially molten mantle: one dominated by the magmatism–mantle upwelling feedback (MMUb), and another governed by porosity waves. A key prediction is that the MMUb feedback becomes significant only when the spatial extent of partially molten regions exceeds a threshold scale, implying differences between hotspot volcanism and Large Igneous Provinces (LIPs).

While Earth-based observations permit estimates of source-region scales for LIPs and hotspots, the authors note a lack of comparable constraints for other planets such as Mars, where both types of volcanism are present. Without these measurements, testing the model’s scale-dependent predictions and distinguishing the operative ascent mechanisms remains unresolved.