The identification and classification of minerals on the Martian surface can provide important information and constraints on the environmental and geological evolution. In-situ observations by the Martian Curiosity rover at the landing site in the Gale region provided evidence of water molecules, sulfur, and chlorine, as well as hydrous phyllosilicates. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) has enhanced spectral resolution and can provide information across much greater spatial and time scales. In this paper, CRISM near-infrared spectral data are used to identify mineral classes and their distributions in the Martian Gale and Nili Fossae regions.
Using multiple spectral parameter analysis for the Gale Crater region, the distributions of important mineral classes have been mapped, including mafic minerals, hydrated minerals, and carbonates. Using the diagnostic absorption feature from 1.0 to 2.6 μm, six hydrous mineral species are mapped in the Nili Fossae region, including kaolinite, nontronite, chlorite, and vermiculite, which are mostly formed by the weathering or hydrothermal alteration. Specifically, the formation of nontronite needs moderate pH and reducing conditions, which are favorable for the preservation of organic materials.
Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates. In December 2011, Opportunity Rover discovered a vein of gypsum sticking out of the soil. Tests confirmed that it contained calcium, sulfur, and water. The mineral gypsum is the best match for the data. It likely formed from mineral-rich water moving through a crack in the rock. The vein, called 'Homestake,' is in Mars' Meridiani plain.
The detection of these minerals in the Nili fossae region suggests that the region has experienced long-term weathering and hydrothermal effects. Previous article in issue.
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