New research sheds light on the formation of Mars’s first crust. Experiments show that the young planet may have formed a thick, white crust as a global ocean of magma cooled. The discovery changes our understanding of Mars’s early interior and may help us better understand future research findings on the Red Planet.
The research by geoscientists Xue Wang, Yanhao Lin, and VU Professor of Planetary Evolution Wim van Westrenen has been published in *Science Advances*.
How did Mars’s first solid crust form? The researchers simulated this process in laboratory experiments under high temperatures and high pressure. Their results show that as the young planet cooled, a layer more than thirty kilometers thick may have formed, rich in the minerals plagioclase and quartz.
In the early stages of its existence, Mars was likely largely covered by an ocean of molten rock. This so-called magma ocean gradually cooled, causing minerals to crystallize and the planet’s various layers to take shape. This process helped determine how the first crust formed, how the mantle developed, and which gases ultimately ended up in the atmosphere.
A Different View of Mars’s Formation
The researchers simulated the solidification of this magma ocean based on updated estimates of the composition and size of the Martian mantle. In doing so, they drew on insights into Mars’s interior obtained in part by the InSight lander.
The experiments suggest that, under relatively oxidizing conditions, various minerals first formed in the mantle. In the final stages of the cooling process, a thick, relatively light, and buoyant white-colored primordial crust then formed. Mars’s current red color, therefore, did not develop until later, when iron-rich magma broke through this primordial crust.
This finding clearly differs from earlier models, which focused primarily on the minerals in the mantle and paid less attention to the materials that formed during the final stages of cooling.
Furthermore, the new results are consistent with observations of Mars from space. These observations point to the presence of ancient rocks that are rich in plagioclase and have a relatively low density. Thus, the study offers a possible explanation for the composition of parts of Mars’s surface.
Implications for the Planet’s Interior
The discovery also has implications for our understanding of Mars’s internal structure. Differences in density between rock layers can determine how material moves within the mantle. When layers become unstable, they can shift position. Such movements, also known as mantle overturn, can influence the evolution of the planet’s interior and volcanic activity.
The new insights therefore help researchers not only understand which minerals formed on early Mars, but also how the planet continued to evolve thereafter.
A Better Understanding of Mars’s Formation and Evolution
The impact of the discovery lies primarily in the advancement of scientific knowledge. A better understanding of Mars’s formation and evolution helps researchers reconstruct the history of our neighboring planet more accurately.
In addition, the research can guide the analysis of Martian meteorites and rock samples brought back to Earth by future Mars missions. By comparing such materials with the predictions from laboratory experiments, researchers can test whether their models match the actual composition of Mars.
The study demonstrates how experiments on Earth, combined with data from space missions, can yield new insights into the formation of another planet. The researchers thus provide a renewed framework for studying Mars’s oldest rocks and the evolution of its interior.
Photo: NASA