Oxidative alteration of ferrous smectites and implications for the redox evolution of early Mars.

ABSTRACT: Surface conditions on early Mars were likely anoxic, similar to early Earth, but the timing of the evolution to oxic conditions characteristic of contemporary Mars is unresolved. Ferrous trioctahedral smectites are the thermodynamically predicted products of anoxic basalt weathering, but orbital analyses of Noachian-aged terrains find primarily Fe³⁺-bearing clay minerals. Rover-based detection of Fe²⁺-bearing trioctahedral smectites at Gale Crater suggest that ferrous smectites are the unoxidized progenitors of orbitally-detected ferric smectites. To assess this pathway, we conducted ambient-temperature oxidative alteration experiments on four synthetic ferrous smectites having molar Fe/(Mg+Fe) from 1.00 to 0.33. Smectite suspension in air-saturated solutions produced

SUBMITTER: Chemtob SM 

PROVIDER: S-EPMC7427814 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature