Interrelationships in the Gypsum-Syngenite-Gorgeyite System and Their Possible Formation on Mars
Document Type
Article
Publication Date
3-10-2021
Publication Title
Astrobiology
Volume
21
Issue
3
First page number:
332
Last page number:
344
Abstract
Calcium sulfates are known to be potential reservoirs of organic compounds and have been detected on Mars. However, not all data that indicate the presence of sulfates collected by the (Mars Exploration Rovers: Spirit and Opportunity) and Curiosity rovers can be explained by the different calcium sulfate polymorphs, and therefore, mixtures of calcium sulfates with other single sulfates must be considered. In addition, the presence of mixed calcium sulfates supports the data and indicates that the molar ratio of sulfate/calcium is >1. To obtain adequate spectroscopic information of mixed-cation sulfates to be used in the interpretation of data from Mars in the next few years, the thermodynamically stable syngenite (K2Ca(SO4)(2)center dot H2O) and gorgeyite (K2Ca5(SO4)(6)center dot H2O) mixed-cation sulfates have been studied along with the interrelationships in the gypsum-syngenite-gorgeyite system to understand their possible formation on Mars. Raman spectroscopy and Visible-Near Infrared-Shortwave Infrared (VisNIR) spectroscopy have been used for their characterization to increase the databases for the two future Mars exploration missions, Mars2020 and Exomars2022, where both techniques will be implemented. These VisNIR data can also help with the interpretation of spectral data of salt deposits on Mars acquired by the OMEGA and CRISM spectrometers onboard the Mars Express and Mars Reconnaissance orbiters. This work demonstrates that syngenite (K2Ca(SO4)(2)center dot H2O) easily precipitates without the need for hydrothermal conditions, which, depending on the ion concentrations, may precipitate in different proportions with gypsum. Furthermore, in this study, we also demonstrate that, under hydrothermal conditions, gorgeyite (K2Ca5(SO4)(6)center dot H2O) would also be highly likely to form and may also be identified on Mars together with syngenite and gypsum.
Keywords
Syngenite; Görgeyite; Raman; VisNIR; Synthesis and characterization
Disciplines
Astrophysics and Astronomy | Earth Sciences | Geology | Physical Sciences and Mathematics
Language
English
Repository Citation
García-Florentino, C.,
Gomez-Nubla, L.,
Huidobro, J.,
Torre-Fdez, I.,
Ruíz-Galende, P.,
Aramendia, J.,
Hausrath, E. M.,
Castro, K.,
Arana, G.,
Madariaga, J. M.
(2021).
Interrelationships in the Gypsum-Syngenite-Gorgeyite System and Their Possible Formation on Mars.
Astrobiology, 21(3),
332-344.
http://dx.doi.org/10.1089/ast.2020.2319