EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

Abstract

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface.

New Martian Dust Simulant JMDS‐1 and Applications to Laboratory Thermal Conductivity Measurements

“…Specifically, Curiosity rover has detected ∼2.8 wt% magnetite, ∼1.6 wt% hematite, and ∼1.4 wt% anhydrite minor phases in the eolian sediment from the Namibdune, Gale crater (Achilles et al., 2017). Also, carbonate and clay minerals (e.g., calcite and kaolin) are commonly observed on Mars by remote data (Cuadros & Michalski, 2013; Roush, 2021; Ye & Michalski, 2021) and within Martian meteorites (García‐Florentino et al., 2021; Kirschvink et al., 1997; Nakada et al., 2021). These components were therefore chosen as additional materials for the development of Martian dust simulant (see Table 3).…”