Tracking Deep Mantle Melting on Mars Using Phobos Tides
Abstract
We study the deep internal structure and rheological state of Mars by analyzing its response to tidal forces exerted by Phobos and by introducing a melt fraction in the mantle layers. Motivated by recent seismic evidence for a basal molten layer near the base of the Martian mantle, we explore the distribution of melt within the mantle and its influence on the tidal response. Assuming a 3‐layers mantle structure, tidal deformations alone provide a radially dependent melt fraction profile, with partial melting concentrated in the deepest layer. Adding thermal constraints from recent solidus and liquidus determinations refines these limits, confirming that only the deepest part of the mantle might exhibit significant melting. The inferred densities for the mantle and core align with previous studies and point toward iron‐rich mantle layers and a core enriched in light elements. The excess density of the deepest layer favors iron enrichment rather than hydration. Viscosity reduction profiles suggest a transition from solid to partially molten behavior above the core‐mantle boundary, consistent with the presence of a thin basal molten layer enriched in iron and radiogenic elements. However, the rheological parameters and deviate from laboratory estimates for terrestrial materials, suggesting that the anelastic behavior of the Martian mantle may differ from terrestrial analogs. This highlights the need for experimental studies on iron‐rich, melt‐bearing compositions representative of Mars.
Related
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- Melting from 1000°C and geophysical discontinuities in the shallow Earth’s mantle
- Coupled thermochemical evolution of the early Earth’s solid mantle and basal magma ocean: The role of melting and melt transport
- Deep seismo-volcanic tremors constrain the magma supply from the mantle
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BibTeX
@article{guinard2026tracking,
title = {{Tracking Deep Mantle Melting on Mars Using Phobos Tides}},
author = {Alex Guinard and A. Fienga and A. Mémin and D. Antonangeli},
journal = {Journal of Geophysical Research. Planets},
year = {2026},
month = sep,
doi = {10.1029/2026je009726},
url = {https://hal.science/hal-05753637v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Tracking Deep Mantle Melting on Mars Using Phobos Tides
AU - Alex Guinard
AU - A. Fienga
AU - A. Mémin
AU - D. Antonangeli
PY - 2026
DA - 2026/09/17
JO - Journal of Geophysical Research. Planets
DO - 10.1029/2026je009726
UR - https://hal.science/hal-05753637v1
AB - We study the deep internal structure and rheological state of Mars by analyzing its response to tidal forces exerted by Phobos and by introducing a melt fraction in the mantle layers. Motivated by recent seismic evidence for a basal molten layer near the base of the Martian mantle, we explore the distribution of melt within the mantle and its influence on the tidal response. Assuming a 3‐layers mantle structure, tidal deformations alone provide a radially dependent melt fraction profile, with partial melting concentrated in the deepest layer. Adding thermal constraints from recent solidus and liquidus determinations refines these limits, confirming that only the deepest part of the mantle might exhibit significant melting. The inferred densities for the mantle and core align with previous studies and point toward iron‐rich mantle layers and a core enriched in light elements. The excess density of the deepest layer favors iron enrichment rather than hydration. Viscosity reduction profiles suggest a transition from solid to partially molten behavior above the core‐mantle boundary, consistent with the presence of a thin basal molten layer enriched in iron and radiogenic elements. However, the rheological parameters and deviate from laboratory estimates for terrestrial materials, suggesting that the anelastic behavior of the Martian mantle may differ from terrestrial analogs. This highlights the need for experimental studies on iron‐rich, melt‐bearing compositions representative of Mars.
SN - 2169-9097
SN - 2169-9100
ER -