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Phoenix666 writes:

The new study looks at twenty-two light-colored, igneous rocks Curiosity inspected, half of which got the laser treatment. The rocks fell into three groups. Some were made up of large crystals, indicating that they cooled slowly, below ground. Some were made up of microscopic crystals and were riddled with bubbles, indicating that they erupted from a volcano. And the third group was a sort of hybrid, with large crystals of one mineral surrounded by tiny crystals of others—often the product of a magma that cools slowly for a while before erupting.
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The specific chemical varieties include things not found on Mars before. But apart from rounding out Mars’s rock collection, they have some pretty interesting things to tell us about Mars’s early history. The granite-like rocks are similar to some of the rocks that make up Earth’s earliest truly continental crust, which differs from the basalt that makes up the seafloor. That could have come about by partly melting pre-existing basalts that began to sink back into Mars’s still-soft interior, for example.

Regardless of how it happened, the idea that there was continental crust being manufactured on Mars makes that planet’s early history look more like the Earth’s than we thought. The researchers also note that the existence of some of these rocks “challenge[s] the simple idea of continuous cooling of the Martian mantle over geologic time, pointing to more complex global or local variation in mantle temperature”.

The lithosphere would be an exciting new region for Mars exploration. If those looking for life there are on to something with the hypothesis that any life that evolved may have retreated far underground, it seems the logical next step for them as well. How would we get at those secrets without landing men on Mars?