Convective activity in a Martian magma chamber recorded by P‐zoning in Tissint olivine

Abstract

The Tissint Martian meteorite is an unusual depleted olivine-phyric shergottite, reportedly sourced from a mantle-derived melt within a deep magma chamber. Here, we report major and trace element data for Tissint olivine and pyroxene, and use these data to provide new insights into the dynamics of the Tissint magma chamber. The presence of irregularly spaced oscillatory phosphorous (P)-rich bands in olivine, along with geochemical evidence indicative of a closed magmatic system, implies that the olivine grains were subject to solute trapping caused by vigorous crystal convection within the Tissint magma chamber. Calculated equilibration temperatures for the earliest crystallizing (antecrystic) olivine cores suggest a Tissint magma source temperature of 1680°C, and a local Martian mantle temperature of 1560°C during the late Amazonian-the latter being consistent with the ambient mantle temperature of Archean Earth. Mineral Chemistry as a Probe for Martian Magma Dynamics Paleo-heat flows deduced from lithospheric strength suggest that the "stagnant-lid" tectonic regime of Mars has enabled mantle heat retention for the majority of the planet's history (

The Tharsis mantle source of depleted shergottites revealed by 90 million impact craters

“…Long-lived ( 147 Sm- 143 Nd, 87 Rb- 87 Sr, 176 Lu- 177 Hf, 187 Re- 188 Os, 233,238 U- 232 Th- 206,207,208 Pb) and short-lived ( 146 Sm- 142 Nd, 182 Hf- 182 W) isotopic composition of the depleted shergottites 4 indicate, respectively, that they sampled a highly depleted mantle formed early in Mars history, during the differentiation of the Martian magma ocean (MMO), ∼4.5 Gyr ago 4 , 27 . In addition, considering that olivine phenocrysts in the ol-phyric depleted shergottites are in near-equilibrium with their parental melt, the potential mantle temperature (Tp) can be estimated from 1714 to 1835 °C 28 , 29 . This is hotter than estimates from in situ rock analyses in Gusev (1300°–1500 °C), Meridiani (1400 °C) or Gale crater (1250–1500 °C) 28 – 30 .…”

“… a Pressure-temperature-depth phase diagram for the Martian mantle 28 . The adiabatic range for the depleted shergottites (in red) extrapolated using mantle potential temperature 28 , 29 , 32 , suggests that melting potentially occurs below 10 GPa (1), within the transition zone (2) and possibly down to the core-mantle boundary (3), i.e. between ~800 and ~1600 km.…”

MaQuIs - Mars Quantum Gravity Mission

“…Such a dedicated gravity mission would improve the static gravitational field model of Mars, determine its temporal components, and allow to pinpoint the distribution of water with a higher accuracy then current orbital missions. Additionally, a more detailed knowledge of the gravitational field distribution paves the way to improving not only the depth resolution of subsurface lakes and their distribution around the entire planet, but also to identify and characterise other buried mass structures like hidden impact craters (Frey et al, 2002) and magma chambers (Mari et al, 2020;Broquet & Andrews-Hanna, 2022).…”