Rani, A.A.RaniBasu Sarbadhikari, A.A.Basu SarbadhikariHood, D. R.D. R.HoodGasnault, O.O.GasnaultNambiar, S.S.NambiarKarunatillake, S.S.Karunatillake2025-08-312025-08-312022-07-2810.1029/2022GL0992352-s2.0-85135180793http://repository.iitgn.ac.in/handle/IITG2025/26002Chemical provinces were defined on Mars a decade ago using orbital nuclear spectroscopy of K, Th, Fe, Si, Ca, Cl, and H<inf>2</inf>O. 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.falseArticlehttps://hal.science/hal-038408771944800728 July 202210e2022GL099235arJournal10