Interior dynamics and thermal evolution of Mars – a geodynamic perspective

The Temperature and Composition of the Mantle Sources of Martian Basalts

“…The mantle temperature of the sources that gave rise to known primitive basalts appears to have remained relatively stable through time ( T p of 1400–1500°C) but is likely due to a sampling bias. The higher mantle T p (∼1600°C) of the Hesperian volcanic provinces (Baratoux et al., 2011), recalculated with MAGMARS and assuming a mantle of Mg# 79 or higher (Khan et al., 2022; Yoshizaki & McDonough, 2020), hint at a significant secular cooling (>100°C), as expected from thermochemical evolution models (Plesa et al., 2022). The shergottite melts were likely produced at pressures greater than 3 GPa but re‐equilibrated with the lithospheric mantle at 1–2 GPa, for example, at the base of the thick Tharsis crust.…”

“…This could be due to the limited number of primitive basalts available that might not be representative of the average mantle. To test this possibility, we compare the mantle temperature estimates derived from MAGMARS to the results of a global thermochemical evolution model incorporating the most recent interior structure constraints from InSight (Plesa et al., 2022). This model predicts that the average mantle temperature—and maximum temperature at which basaltic melts can be produced (Figure 3a)—should first increase due to the decay of radioactive elements and peak at 4.0–3.5 Ga before slowly decreasing.…”

“…The rounded fields are the sources of the Gamma Ray Spectrometer volcanic provinces of Baratoux et al (2011), re-calculated with MAGMARS. The black lines represent the evolution of the potential temperatures and pressures of the part of the mantle that is affected by partial melting in the thick-crust geodynamical model of Plesa et al (2022). The minimum pressure of melting (dashed line in B) can be interpreted as the thinnest thermal lithosphere observed anywhere on the planet.…”

“…Model compositions of the “primitive mantle” were rapidly put forth (e.g., Dreibus & Wänke, 1985) and allowed to create simple models of the Martian interior structure (Bertka & Fei, 1997; Elkins‐Tanton et al., 2003; Longhi et al., 1992). Additional analyses of crustal rocks by subsequent orbiting probes and rovers, the discovery of new Martian meteorites (Agee et al., 2013; Humayun et al., 2013), geodetic and seismic data from the recent InSight mission (e.g., Huang et al., 2022; Khan et al., 2021), and geodynamic modeling (e.g., Plesa et al., 2022), are now allowing to draw ever improving representations of the interior structure of Mars and its evolution through time.…”

Mapping the Seismicity of Mars With InSight

“…Finally, we provide distances for the events with lower SNR by finding the best matches to the collection of high‐quality template events, with addition insights from backazimuths in some cases, and separate the seismicity into classes (Figure 5). In our analysis, we focus on signal similarity as a main criterion across different seismic events and leave out other complexities associated with their source (Stähler et al., 2021) or 3D structural effects (Kim, Duran, et al., 2023; Plesa et al., 2022), which still remain largely unaccounted for.…”