Volcanism on Mars controlled by early oxidation of the upper mantle
The compositions of the 3.7-billion-year-old surface rocks on Mars — as observed by the Spirit rover at Gusev crater — are shown to be consistent with early mixing of oxidized surface material into the uppermost Martian mantle: such oxidation appears to have had less influence on more recent volcanic rocks, which are sampled as Martian meteorites.
Full article in Nature
