Researchers at the University of Oxford have found evidence that Mars may once have contained enormous Earth-like magmatic systems deep below its surface, even though the planet does not have the plate tectonics that scientists have long associated with this level of geological complexity. The findings, published in Nature Astronomy, point to new possibilities for how rocky planets can evolve in ways that may support habitability. Mars is commonly classified as a "stagnant lid" planet because, unlike Earth, its outer shell is not divided into moving tectonic plates.
On Earth, plate tectonics plays a major role in volcanism, recycling crustal material and helping build continents. Because Mars lacks this process, scientists have often assumed that its crust formed in a much simpler way. The new study challenges that assumption.
The results suggest that Mars may have developed highly evolved crust through vigorous recycling within the planet itself, without the need for Earth-style plate tectonics. A Mysterious Boundary 24 Kilometers Down The researchers analyzed seismic data collected by NASA's InSight mission, focusing on waves generated by meteoroid impacts and marsquakes, the Martian equivalent of earthquakes. Scientists from Oxford's Departments of Earth Sciences and Statistics used those measurements to study an unexplained boundary roughly 24 kilometers beneath the Martian surface.
Earlier research had identified the boundary, but its meaning remained unclear. To investigate whether it represented a transition between different kinds of rock, the team compared the seismic observations with hundreds of possible rock compositions. They combined thermodynamic modeling with statistical methods to determine which materials best matched the properties detected at different depths.
The analysis showed that rocks beneath the 24 km boundary were best explained by "ultramafic" material (rich in iron and magnesium, but low in silica). Above the boundary, the seismic properties were more consistent with "mafic" rocks (containing a higher proportion of silica). The researchers think the buried layer formed when molten rock accumulated deep underground and gradually separated into different materials.
In this process, dense crystals would have settled near the bottom of the crust, while lighter and more chemically evolved melts moved upward. On Earth, similar processes occur beneath volcanic arcs and are associated with the formation of continents. Tobermory Mackay-Champion (Department of Earth Sciences, University of Oxford at the time of the study, now University of Bristol) said: "We've traditionally assumed that volcanism on Mars was relatively simple compared to that on Earth.
Extract — continue reading at the source.
