Infrared Spectral Evidence for K-Metasomatism of Volcanic Rocks on Mars

Potassium metasomatism is a common geologic process occurring in a range of environments on Earth. K-metasomatism can dramatically change the chemistry of large volumes of crust resulting in formation of abundant K-rich feldspar while preserving original rock textures. Remote sensing of Mars has revealed the presence of rare but striking felspar-rich terrains as well as K-rich phyllosilicates such as illite or muscovite. Furthermore, the Curiosity Rover has detected evidence for K-enrichment in rocks at Gale Crater. In this study, we use spectroscopic and remote sensing analyses of K-metasomatized rocks on Earth as a comparison to K-rich and/or possible granitic rocks on Mars. The results suggest that evidence for K-feldspar rich, quartz-bearing, and illite-bearing rocks on Mars is consistent with K-metasomatism. K-rich rocks in Gale Crater have themselves likely not been metasomatized, but the abundant feldspar within them might have been derived from metasomatized crust.