Drilleau, Melanie ; Samuel, Henri ; Verhoeven, Olivier ; Rivoldini, Attilio ; Collinet, Max ; Garcia, Raphael F. ; Lognonné, Philippe Henri

Poster presented at AGU 2025 Fall meeting, New Orleans, USA on 2025-12-16

Abstract: Understanding the deep interior of Mars is key to reconstructing its geological evolution, thermal history, and present-day dynamics. NASA's InSight mission has yielded a valuable seismic dataset, enabling constraints on crustal, mantle, and core properties. However, strong trade-offs between temperature and composition in seismic interpretations limit the resolution of interior models. To overcome this challenge, we incorporate electromagnetic induction data from Mars Global Surveyor as an additional and independent constraint. We present a joint probabilistic inversion framework that simultaneously fits body-wave arrival times, electrical conductivity, the tidal Love number k2 , and the planet’s moment of inertia. A central aspect of our method is the integration of Mars’ long-term thermal evolution into the forward modeling, together with mineral physics and petrological constraints, allowing us to directly constrain key geodynamical parameters. We investigate three mantle compositions with variable Mg content [1, 2, 3], and compare homogeneous models to those that include a molten basal layer in the lower mantle [4]. For homogeneous mantle models, two families of solutions are found for each mantle composition: one with low Mg content and high potential temperature, which better reproduces electrical conductivity profiles due to a thicker lithosphere, and another with higher Mg content and lower temperatures. In contrast, models with a basal molten layer generally yield thinner lithospheres and fit the conductivity data less accurately. Furthermore, the mantle composition of [3] appears less consistent with the combined dataset. Our results highlight the value of electromagnetic data in resolving the Martian interior, and suggest that future efforts should aim to improve both the quality of induction measurements and the seismic constraints on mantle phase transitions.

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Funding: 3PRODPLANINT/3PRODPLANINT/3PRODPLANINT