Evolved magma on Mars

摘要

Earth is distinguished from the other terrestrial planets by its continents, which are largely made of low-density rocks termed felsic - that is, rich in silica and the mineral feldspar. These rocks are formed from magma through extensive melting and subsequent recrystallization, and are abundant on Earth. In contrast, the surface of Mars is dominated by denser, iron-rich basaltic rocks~1 that have experienced little magmatic evolution, similar to the rocks beneath Earth’s oceans. However, writing in Nature Geoscience, Wray et al.~2 and Carter and Poulet~3 present spectral satellite data that reveal the presence of feldspar-rich rocks throughout the ancient southern highlands of Mars. These rocks signal a whole new suite of magmatic processes on Mars, and may help scientists understand the origin of the felsic rocks and soils that have been identified at the Curiosity rover’s landing site in Gale Crater~(4-6) (Fig. 1).