Early crust on Mars may be more complex than previously thought—and it may even be similar to our own planet’s original crust.
The Martian surface is uniformly basaltic, a product of billions of years of volcanism and flowing lava on the surface that eventually cooled. Because Mars did not undergo full-scale surface remodeling like the shifting of continents on Earth, scientists had thought Mars’s crustal history was a relatively simple tale.
But in a new study, researchers found locations in the Red Planet’s southern hemisphere with greater concentrations of silicon, a chemical element, than what would be expected in a purely basaltic setting. The silica concentration had been exposed by space rocks that slammed into Mars, excavating material that was embedded miles below the surface, and revealing a hidden past. The study, “An evolved early crust exposed on Mars revealed through spectroscopy,” was published online Nov. 4 in the journal Geophysical Research Letters.
“There is more silica in the composition that makes the rocks not basalt, but what we call more evolved in composition,” says Valerie Payré, assistant professor in the Department of Earth and Environmental Sciences at the University of Iowa and the study’s corresponding author. “That tells us how the crust formed on Mars is definitely more complex than what we knew. So, it’s more about understanding that process, and especially what it means for how Earth’s crust first formed.”
Scientists believe Mars formed about 4.5 billion years ago. Exactly how the Red Planet came into being is a mystery, but there are theories. One idea is that Mars formed via a titanic collision of rocks in space, that with intense heat spawned an entirely liquefied state, also known as a magma ocean. The magma ocean gradually cooled, the theory goes, yielding a crust, like a layer of skin, that would be singularly basaltic.
Another theory is that the magma ocean was not all-encompassing, and that parts of the first crust on Mars had a different origin, one that would show silica concentrations different from basaltic.
