Chemical weathering and diagenesis of a cold desert soil from Wright Valley, Antarctica: An analog of Martian weathering processes

Abstract

Weathering, diagenesis, and chemical alteration of a soil profile from the Dry Valleys of Antarctica have been studied as an analog to soil development within the Martian regolith. Soil samples from a one‐meter‐deep soil pit on Prospect Mesa, Wright Valley, have been examined for their major element concentrations, water soluble cations and anions, carbon, sulfur, and water concentrations, and related petrographic characteristics of weathering in a cold, dry environment. Petrographic study of the soil samples indicates that most silicate mineral and lithic fragments exhibit some degree of alteration. Chemical alteration occurs in samples both from above and from within the permanently frozen zone. Concentrations of water soluble cations (Na+, K+, Ca2+) and anions (Cl−, SO42−, NO3−) decrease significantly from the surface to the permanently frozen zone, suggesting major movement of water soluble species. Enrichments in secondary mineral abundances correlate with the water soluble ion concentrations. Formation of zeolites is observed throughout the soil column and may be potential reservoirs for volatile storage within the regolith. From the detailed study of the Dry Valley soils, an idealized soil profile for the regolith has been developed and is suggested as applicable to other planetary surfaces, especially the Martian nearsurface environment. The soil profile consists of four zones: aeolian, salt, active, and permanently frozen.