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A few months ago, NASA scientists noticed some surprisingly light-colored rocks in a photograph. They shouldn’t have been so light, by their understanding of the area’s geology — and so naturally, these scientists sent Curiosity to go and blast those rocks with a laser. The onboard “ChemCam” experiment then looked into the chemical composition of the vaporized rock this produced — and what it found looked surprisingly familiar. Though it has long been believed that Mars never had distinct continental plates, this new evidence suggests that Mars may once have had continents much like those on primordial Earth.
Some commentators are jumping from this observation to the idea that with continents must come liquid oceans between those continents, but this study doesn’t actually present any evidence in favor of that idea. What it does say is that spectral analysis of 22 light-colored rocks found near the Gale Crater show a high feldspar content, and likely quartz content too, and that the samples bear a striking overall resemblance to a type of Earth rock called Tonalite-Trondhjemite-Granodiorite (TTG). TTG is characteristic of Earth continental crust formations from this planet’s Archaen period, which ended some 2.5 billion years ago.
Mars had been widely theorized to be mostly “basaltic,” made of dark, relatively dense igneous rock of the sort found on Earth’s ocean floors. There was little support for the idea of distinct continental plates on Mars, even in the planet’s ancient history, but that seems to be the simplest explanation for this week’s reported findings. The light, granite-like rocks seem to suggest that around 4 billion years ago, Mars could have been much more Earth-like than previously believed.
originally posted by: intrptr
Isn't Mars one big continent?
There has been some evidence previously discovered that suggests Mars shows some aspects of plate tectonics.