With respect to global tectonics the present day Mars is considered as a single plated planet. Due to the lack of consumptive plate tectonics the regolith, which accumulated at the Martian surface, represents a long-term archive of exogenic processes and contains a record of the evolution of surface conditions on ancient Mars.

Compositional data analysis by means of clr-biplot visualization techniques provides a clear separation of Martian surface samples (Fig. 1). Furthermore, chemical weathering rinds are observed to be significantly different in composition from soil and fresh rock, but appear as intermediate stage of soil formation.

Compositional vector analysis provides clues on soil formation pathways and rock alteration trends. The deduction of alteration vectors in MER-A basalts gives evidence for the release of Mg and Fe species upon attack of volcanic gases and acidic fluids, which is consistent with models and experiments on acid-sulfate weathering of olivine-bearing basaltic rocks.

Soil formation vectors originating from basalt-andesitic and MER-A basaltic sources are compositionally symmetric in their relative appearance, which indicates global interference via remote weathering by adherence of K-chlorides and Mg-sulfates on basalts and basalt- andesites, respectively.