Distinguishing The Geochemical Effects Of Sedimentary Processes And Source Region Characteristics In Gale Crater, Mars.

The NASA Curiosity rover has investigated a diverse stratigraphic record at Gale crater, Mars, ranging from poorly-sorted conglomerates to cross-bedded sandstones and thinly-laminated mudstones. This stratigraphic record is indicative of deposition in multiple paleoenvironments (fluvial, lacustrine and aeolian), within which variable degrees of mineral sorting, chemical weathering and post-depositional aqueous alteration occurred. This study delineates the geochemical effects of these different sedimentary processes using major element data from the Chemistry and Camera (ChemCam) instrument suite and mineralogical data provided by the Chemistry and Mineralogy (CheMin) instrument suite to identify source region characteristics, mineral sorting regimes, variations in chemical weathering, and the impact of diagenesis on the geochemistry of the host rock. Delineating the different geochemical effects of these sedimentary processes on the lithified units will better constrain our understanding of the geological record and paleoenvironmental conditions in Gale crater, along with the extent of geochemical variation in the surrounding Martian crust. Here, I show that four previously identified compositional endmembers (subalkaline basalt, trachybasalt, trachyte and rhyolite), and one new endmember (silica-rich basalt) contributed to Gale crater’s stratigraphic groups. The previously identified endmembers’ influence extends throughout Gale crater’s stratigraphic record beyond where they were initially identified. The silica-rich basalt source region is the main contributor to the lower Mt Sharp Group, including the Vera Rubin Ridge, whose hardness likely results from a later diagenetic event precipitating additional hematite in sedimentary pore spaces. This thesis further supports that Martian fluviolacustrine deposits are more enriched in felsic material relative to mafic material with distance from the sediment source. Meanwhile, aeolian deposits become preferentially enriched in mafic materials. Geochemically identifying the ancient aeolian mineral sorting trend has also constrained the prevailing wind direction at the time of deposition as SW-NE, which is the reverse of the current prevailing wind direction within Gale crater today

Using ChemCam derived geochemistry to identify the paleonet sediment transport direction and source region characteristics of the Stimson formation in Gale crater, Mars.

The NASA Curiosity rover has encountered both ancient and modern dune deposits within Gale crater. The modern dunes are actively migrating across the surface within the Bagnold Dune field of which Curiosity conducted analysis campaigns at two different localities. Variations in mafic-felsic mineral abundances between these two sites have been related to the aeolian mineral sorting regime for basaltic environments identified on the Earth which become preferentially enriched in olivine relative to plagioclase feldspar with increasing distance from the source. This aeolian mineral sorting regime for basaltic minerals has also been inferred for Mars from orbital data. The aim of this study is to investigate whether this aeolian mafic-felsic mineral sorting trend has left a geochemical signature in the ancient dune deposits preserved within the Stimson formation. The Stimson formation unconformably overlies the Murray formation and consists of thickly laminated, cross-bedded sandstone. Stimson outcrops have a variable thickness up to 5 meters covering a total area of 17 square kilometers. A dry, aeolian origin was determined for this sandstone due to the high sphericity and roundness of the grains, uniform bimodal grain size distribution (250-710 microns), and 1-meter-thick cross-beds. Identifying the geochemical signature of mineral sorting can provide insights about the paleo-net sediment transport direction of the dunes and prevailing wind direction at the time of deposition

An insight into ancient aeolian processes and post‐Noachian aqueous alteration in Gale crater, Mars, using ChemCam geochemical data from the Greenheugh capping unit

Aeolian processes have shaped and contributed to the geological record in Gale crater, Mars, long after the fluviolacustrine system existed ∼3 Ga ago. Understanding these aeolian deposits, particularly those which have been lithified and show evidence for aqueous alteration, can help to constrain the environment at their time of deposition and the role of liquid water later in Mars’ history. The NASA Curiosity rover investigated a prominent outcrop of aeolian sandstone within the Stimson formation at the Greenheugh pediment as part of its investigation of the Glen Torridon area. In this study, we use geochemical data from ChemCam to constrain the effects of aeolian sedimentary processes, sediment provenance, and diagenesis of the sandstone at the Greenheugh pediment, comparing the Greenheugh data to the results from previous Stimson localities situated 2.5 km north and >200 m lower in elevation. Our results, supported by mineralogical data from CheMin, show that the Stimson formation at the Greenheugh pediment was likely sourced from an olivine-rich unit that may be present farther up the slopes of Gale crater’s central mound. Our results also suggest that the Greenheugh pediment Stimson formation was cemented by surface water runoff such as that which may have formed Gediz Vallis. The lack of alteration features in the Stimson formation at the Greenheugh pediment relative to those of the Emerson and Naukluft plateaus suggests that groundwater was not as available at this locality compared to the others. However, all sites share diagenesis at the unconformity

Community Resilience Through Communication

https://digitalcommons.stmarys-ca.edu/disney-forum/1001/thumbnail.jp

The Impact of Compositional Changes on Random Forest Predictions: Applicationto ChemCam LIBS Data from Gale Crater, Mars

We present statistics on ChemCam LIBS data from Gale crater. Predictions of a random forest classifier are compared to unsupervised clustering of the same data

Tensor Component Analysis for the Investigation of Depth Trends in ChemCam LIBS Data from Gale Crater, Mars

The laser-induced breakdown spectroscopy (LIBS) instrument ChemCam onboard NASA's Curiosity rover measures the chemical composition of Martian targets at remote distances. It ablates material with its laser and can therefore also measure depth profiles when targeting multiple times the same position. We included these so calles shot-to-shot trends as a third dimension in the ChemCam dataset and applied a tensor decomposition technique to it. With this method it is possible to detect correlations of elemental abundances with depth among multiple targets

Tensor component analysis as a tool for investigating depth trends in ChemCam LIBS data from Gale crater, Mars

We apply tensor component analysis (TCA) to ChemCam LIBS shot to shot data which allows to investigate depth trends in an unsupervised fashion

Clustering Supported Classification of ChemCam Data From Gale Crater, Mars

International audienc

RECONSTRUCTION OF AEOLIAN PALAEOENVIRONMENTS AND PAST CLIMATE EVENTS AT THE GREENHEUGH PEDIMENT, AEOLIS MONS, MARS

International audienceThe signature of major and minor climate events can be recorded in the stratigraphic rec-ord of ancient aeolian dune fields. Sustained aridifica-tion may permit construction of dune fields and preservation of aeolian strata in areas previously char-acterized by strata deposited by water in humid condi-tions. Minor climate events may be manifest as episod-ic changes of the prevailing wind – such as direction reversal – can be encoded by changes to the strati-graphic architecture and facies preserved within an accumulating dune field’s stratigraphic succession. By documenting the stratigraphic record and understand-ing how surface processes generate these strata, cli-mate trends at different time scales can be deciphered, allowing more granular reconstruction of the ancient climates.Between Sols 2600 and 2750, the MSL rover inves-tigated the Stimson formation – which unconformably overlies the lacustrine Murray formation [1,2] – at the north edge of the Greenheugh pediment, to determine the depositional origin and processes which formed the capping unit. The pediment capping unit is interpreted to be an up-slope extension of the Stimson formation, and part of the Siccar point group [1,2,3], which are part of the broader “Mound skirting unit” seen across the lower northern flank of Aeolis Mons [4]