Consolidated Chemical Provinces on Mars: Implications for Geologic Interpretations

Abstract

AbstractChemical provinces were defined on Mars a decade ago using orbital nuclear spectroscopy of K, Th, Fe, Si, Ca, Cl, and H2O. However, past multivariate analyses yielded three sets of provinces, suggesting methodologic variability. Province‐stability to the inclusion of Al and S is also unknown, presenting additional uncertainties for geologic insight. Here we consolidate key multivariate methods to define the first cross‐validated provinces. In southern highlands, the highly incompatible K and Th show non‐uniform distribution with higher values in mid Noachian and Hesperian than late Noachian – early Hesperian volcanic terrains. Silica‐ and Al‐depletion trends from Noachian to Amazonian indicate highly differentiated mantle with variable degree of melting. Late Hesperian lowlands are highly depleted in Al and enriched in K and Th, consistent with volcanic resurfacing from a low‐degree partially melted, garnet‐rich mantle. Furthermore, older volatile‐rich regions such as Medusae Fossae Formation exhibit igneous geochemistry, consistent with water‐limited isochemical weathering throughout Mars's history.