Elemental Composition and Chemical Evolution of Geologic Materials in Gale Crater, Mars: APXS Results From Bradbury Landing to the Vera Rubin Ridge

The Alpha Particle X-ray Spectrometer (APXS) on the rover Curiosity has analyzed the composition of geologic materials along a >20-km traverse in Gale crater on Mars. The APXS dataset after 6.5 Earth years (2,301 sols) includes 712 analyses of soil, sand, float, bedrock, and drilled/scooped fines. We present the APXS results over this duration and provide stratigraphic context for each target. We identify the best APXS measurement of each of the 22 drilled and scooped samples that were delivered to the instruments Chemistry and Mineralogy (CheMin; X-ray diffractometer) and Sample Analysis at Mars (SAM; mass spectrometer and gas chromatograph) during this period. The APXS results demonstrate that the basaltic and alkali-rich units in the Bradbury group (sols 0-750) show minimal alteration indicating an arid climate. In contrast, the Murray formation of the Mount Sharp group (sols ∼750-2,301) has compositions indicating pervasive alteration. Diagenetic features are common and show fluid interaction with the sediment after (and possibly during) lithification. A sandstone unit, the Stimson formation, overlies part of the Murray formation. This has a composition similar to the basaltic sand and soil, suggesting a shared source. Cross-cutting, fracture-associated haloes are evidence of late-stage fluid alteration after lithification of the sediment. The APXS dataset, evaluated in concert with the full science payload of Curiosity, indicates that Gale crater was habitable, and that liquid water was stable for extended periods.We are indebted to NASA-JPL, the Canadian Space Agency, and Australian Research Council (DP150104604) for supporting our work and the MSL mission. A portion of this study was conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration

Wheat data in environment 4.

<p>Upper left panel: average differences (over 100 cross-validations) between bagged GBLUP and GBLUP for predictive correlations (PCOR), mean-squared error (PMSE) and absolute value of differences (PABS) between prediction and realization at 10 values of the regularization parameter. Upper right, lower left and lower right panels give the three metrics for lambda values of 5, 100 and 400, respectively.</p