Tectonism of late Noachian Mars: Surface signatures from the southern highlands

Upwelling mantle plumes often instigate extensional stress within the continental crust of
Earth. When stress exceeds crustal strength, extensional structures develop, reducing the effective
stress and trigger magmatic processes at the crust–mantle boundary. However, such processes and
their relationship to the formation of many surface structures remain poorly characterized on Mars.
We identified a series of extensional structures in the southern highlands of Mars which collectively
resemble continental rift zones on Earth. We further characterized these extensional structures and
their surrounding region (area of ~1.8 M km2) by determining the surface mineralogy and bulk regional geochemistry of the terrain. In turn, this constrains their formation and yields a framework
for their comparison with extensional structures on Earth. These terrains are notable for olivine and
high-Ca pyroxene with a high abundance of potassium and calcium akin to alkali basalts. In the case
of Mars, this Earth-like proto-plate tectonic scenario may be related to the plume-induced crustal
stretching and considering their distribution and temporal relationship with the Hellas basin, we
conclude that the plume is impact-induced. Overall, the findings of this work support the presence
of mantle plume activity in the Noachian, as suggested by thermal evolution models of Mars.