Data from: Brine driven destruction of clay minerals in Gale crater, Mars

This repository contains files and non-commercial software associated with
the journal article "Brine Driven Destruction of Clay
Minerals in Gale Crater, Mars."  The article presents
mineralogical, geochemical, and sedimentological observations made by the
Mars Science Laboratory rover Curiosity in an area called Glen
Torridon, Gale crater, Mars. Rocks exposed in Glen Torridon were
deposited in a lake that occupied the floor of Gale crater about 3.5
billion years ago and are stratigraphic and depositional
equivalents of rocks exposed ~ 400m away on Vera Rubin ridge. The
mineralogy of rocks in these two areas are different despite
forming in the same lake at the same time. Glen Torridon rocks
contain about 30 wt % clay minerals and 2 wt % or less of the mineral
hematite (an iron oxide). In contrast, Vera Rubin ridge rocks
contain 5 to 13 wt % clay minerals, with larger quantities
(between 9 and 16 wt %) of iron oxide and oxyhydroxide minerals.
The observed differences in mineralogy are attributed to
preferential post-depositional alteration of Vera Rubin ridge
rocks by silica-poor brines. These brines are thought to
have formed during the deposition of sedimentary strata of the
'sulfate-bearing unit' that overlie Glen Torridon and
Vera Rubin ridge rocks. Orbital spacecraft have
detected magnesium sulfates in the sulfate-bearing unit. The
presence of these highly soluable salts imply that changing
climate and/or hydrological conditions in Gale crater resulted in the
formation of dense brines during deposition of the sulfate-bearing unit.
It is hypothesized that brines infiltrated older
clay-bearing sediments, converting iron-rich clay minerals to iron oxides
and oxyhydroxides. Glen Torridon rocks also contain a mineral
phase not previously identified on the mission. This mineral gives rise to
a distinctive x-ray diffraction peak represents a interplanar spacing of
9.22 angstroms. This phase is identified as a mixed-layer serpentine-talc
and is thought to have been transported into the crater floor by
rivers. This repository contains: - Files needed to perform mineral search
and Rietveld refinement of measured x-ray diffraction data using BGMN and
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 Curiosity. - Python code that was
used to identify the 9.22 angstrom phase through automated search
the American Mineralogist Crystal Structure Database. -
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-4_5-rdr-v1/mslapx_1xxx/extras/) - A compilation of Li abundances across Vera Rubin ridge and Glen Torridon measured by the ChemCam that were presented in the article and used as a proxy for rock clay mineral content.