Data from: Mineralogical Investigation of Mg-sulfate at Gale Crater, Mars.

This dataset contains files associated with the journal article "Crystallographic Investigation of Mg-sulfate at Gale Crater, Mars."

The article presents mineralogical, geochemical, and environmental observations made by the Mars Science Laboratory (MSL) rover, Curiosity, at the Canaima drill site, Gale crater, Mars. Rocks in this area comprise exposures of the “Mg-sulfate-bearing unit”, a long-anticipated area of Mount Sharp at the center of Gale crater, distinguished by detections of hydrated magnesium sulfate minerals in visible near-infrared reflectance spectroscopic measurements made from orbit. The orbital spectroscopic detections of a broad class of “polyhydrated hydrated magnesium sulfate” are not diagnostic of the specific crystalline and non-crystalline phases predicted to be present under contemporary surficial martian conditions, however.

X-ray diffraction data from Canaima drill powders obtained by the CheMin instrument on MSL show the presence of the mineral Starkeyite (MgSO₄•4H₂O). Mass balance calculations, combining bulk sample geochemistry, measured by the Alpha Particle X-ray Spectrometer, and quantitative mineralogical analysis of the XRD data indicate that Canaima also contains amorphous hydrated magnesium sulfate. This conclusion is supported by Chemcam Instrument data. The contemporary hydrated magnesium sulfates detected in Canaima are likely dehydration products (a response to contemporary humidity and temperature conditions at the martian surface and within the Chemin instrument) of epsomite or meridianiite, which originally precipitated from sulfate-laden brines close to the time of deposition or at a later stage from diagenetic/hydrothermal fluids influencing host rocks. Evidence for sulfate brines, the precipitation of highly soluble Mg-sulfates and an increase in the abundance of Mg-sulfates at Canaima at Gale crater are consistent with the idea that the Mg-sulfate unit at Gale corresponds to a global change in climate and budget of liquid water.

This repository contains:

- Files needed to perform mineral search and Rietveld refinement of measured X-ray diffraction data over three nights of analysis, using MDI Jade software.

- A non-commerical Excel-based program called FULLPAT, used for mineral and x-ray amorphous quantification of x-ray diffraction patterns collected by the CheMin instrument aboard MSL.

- Collection times of Alpha Particle X-ray Spectrometer analyses of bulk rock geochemical presented in the article that can be used to retrieve raw data from NASA's Planetary Data system (https://pds-geosciences.wustl.edu/msl/msl-m-apxs-2-edr-v1/mslapx_0xxx/extras/).

- Measured ground temperatures and estimated ground relative humidity (RH) data from Gale, shown in Fig. 3 of the article.

- Table of temperatures measured inside the CheMin instrument during delivery of the Canaima sample, shown in Fig. 7 of the article.

- Links to descriptions of the licenses accompanying the release of files and software hosted in this dataset.