P070-10
Identifying ancient dune processes in the Stimson formation of Gale crater from the Greenheugh pediment to the Emerson Plateau using geochemical data from ChemCam.
Tuesday, 15 December 2020: 06:17
Virtual
Candice Ceilidh Bedford1,2, Steven Banham3, Donald L. Bowden4, John Bridges4, Olivier Forni5, Agnes Cousin6, Patrick James Gasda7, Elizabeth B Rampe2, Olivier Gasnault8, Erwin Dehouck9, Jens Frydenvang10, Roger C Wiens11, Rebecca Smith12, Susanne P Schwenzer13 and Alexander B Bryk14, (1)Lunar and Planetary Institute, Houston, TX, United States, (2)NASA Johnson Space Center, Houston, TX, United States, (3)Imperial College London, London, SW7, United Kingdom, (4)University of Leicester, Leicester, United Kingdom, (5)IRAP-CNRS, Toulouse Cedex 4, France, (6)Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France, (7)Los Alamos National Laboratory, Los Alamos, NM, United States, (8)Universite de Toulouse, Toulouse Cedex 4, France, (9)University Paul Sabatier, Institut de Recherche en Astrophysique et Planétologie, Toulouse, France, (10)Univ. of Copenhagen, Natural History Museum of Denmark, Copenhagen, Denmark, (11)Space Science and Applications, Los Alamos, NM, United States, (12)Stony Brook University, Geosciences, Stony Brook, NY, United States, (13)The Open University, AstrobiologyOU, Milton Keynes, United Kingdom, (14)University of California Berkeley, Earth and Planetary Science, Berkeley, CA, United States
Abstract:
The NASA Curiosity rover has investigated a lithified aeolian dune deposit known as the Stimson formation at three locations by ChemCam: the Emerson Plateau (EP, sols 990–1154), Naukluft Plateau (NP, sols 1279–1352), and most recently at the Greenheugh pediment (GP, sols 2694–2733). The Stimson formation is so far the youngest geological unit analyzed by the Curiosity rover and was deposited after the perennial fluviolacustrine environment that deposited the Bradbury and Mt Sharp Groups, and after significant erosion of the latter, but still at a time when enough groundwater existed to cement the aeolian deposits. In this study, we investigate the ChemCam geochemical data of the Stimson formation using a statistical density analysis, equivalence tests, and a multivariate cluster analysis. Through these statistical methods, we aim to identify geochemical trends associated with aqueous alteration and sandstone components relating to aeolian sorting processes and source compositions.
Results show that the geochemical range of the Stimson formation is similar across all localities, but the distributions and average compositions vary. EP and NP are the most similar to each other but the EP has on average higher MgO and lower Al2O3, Na2O, and K2O relative to the NP. Stimson at the more distant and higher-elevation GP has higher average MgO concentrations and lower Al2O3 and SiO2 concentrations than both EP and NP. Cluster analysis results combined with mineral compositional data from the CheMin instrument show that these geochemical variations between the localities likely relate to differences in the relative abundance of detrital mafic and felsic minerals. Mineral sorting as the dunes migrated SW-NE from NP to EP likely enriched the EP in mafic minerals relative to NP. Mineral sorting is unlikely to have concentrated mafic components to a greater degree at GP as the net-sediment transport direction derived from the analysis at EP and NP indicate that GP should have experienced less transport and hence be more felsic instead of mafic. Instead, it is possible that the sediments preserved at GP may be from a more olivine-rich sediment source compared to those preserved at EP and NP.
