Geochemical variation in the Stimson formation of Gale crater: Provenance, mineral sorting, and a comparison with modern Martian dunes

Bedford, C. C.; Schwenzer, S. P.; Bridges, J. C.; Banham, S. G.; Wiens, R. C.; Gasnault, O.; Rampe, E. B.; Frydenvang, J.; Gasda, P. J.

doi:10.1016/j.icarus.2020.113622

Cited by 41 publications

(121 citation statements)

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“…The unconformably overlying eolian Stimson formation sandstone of the Siccar Point group (Banham et al, 2018) provides evidence for at least one additional episode of burial and erosion because it drapes the Murray formation at the Emerson and Naukluft plateaus (Figures 1b and 2). ChemCam observations from the much younger Stimson formation (see, e.g., Bedford et al, 2020) are not included in the data presented here and thus appear as gaps in the overview of ChemCam Murray formation observations (Figure 1b).…”

Section: Geological Contextmentioning

confidence: 99%

The Chemostratigraphy of the Murray Formation and Role of Diagenesis at Vera Rubin Ridge in Gale Crater, Mars, as Observed by the ChemCam Instrument

et al. 2020

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Geochemical results are presented from Curiosity's exploration of Vera Rubin ridge (VRR), in addition to the full chemostratigraphy of the predominantly lacustrine mudstone Murray formation up to and including VRR. VRR is a prominent ridge flanking Aeolis Mons (informally Mt. Sharp), the central mound in Gale crater, Mars, and was a key area of interest for the Mars Science Laboratory mission. ChemCam data show that VRR is overall geochemically similar to lower‐lying members of the Murray formation, even though the top of VRR shows a strong hematite spectral signature as observed from orbit. Although overall geochemically similar, VRR is characterized by a prominent decrease in Li abundance and Chemical Index of Alteration across the ridge. This decrease follows the morphology of the ridge rather than elevation and is inferred to reflect a nondepositionally controlled decrease in clay mineral abundance in VRR rocks. Additionally, a notable enrichment in Mn above baseline levels is observed on VRR. While not supporting a single model, the results suggest that VRR rocks were likely affected by multiple episodes of postdepositional groundwater interactions that made them more erosionally resistant than surrounding Murray rocks, thus resulting in the modern‐day ridge after subsequent erosion.

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Section: Geological Contextmentioning

confidence: 99%

The Chemostratigraphy of the Murray Formation and Role of Diagenesis at Vera Rubin Ridge in Gale Crater, Mars, as Observed by the ChemCam Instrument

et al. 2020

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“…The ChemCam observations of the Stimson formation exhibit a range of compositions. As described by Bedford (2019) and Bedford et al (2020) there are clear felsic to mafic trends among compositions observed in the Stimson formation. These are consistent with Curiosity observations of Bagnold dunes, where grain segregation is apparent (e.g., Cousin et al, 2017b ; Ehlmann et al, 2017 ; Johnson et al, 2017 ; O’Connell-Cooper et al, 2017 ).…”

Section: Discussionmentioning

confidence: 52%

“…1 ) in an outcrop that also contains some conglomerates ( Williams et al, 2018 ). Overall, the Stimson concretions do not show much deviation from bulk rock composition but for FeO T there are a number of extreme outliers to high FeO T concentrations, particularly in the Naukluft locality (see the boxplot in the Supplementary material ; Bedford, 2019 ; Bedford et al, 2020 ). These concretions may relate to preferential cementation of the sandstone.…”

Section: Resultsmentioning

confidence: 96%

“…2a , 3a, b, e ), observed on sols 1100 and 1102. Of these, Sunburst corresponds to a relatively rare group of Stimson-formation targets referred to as Cluster 1 by Bedford et al (2020) . Sunburst has high MgO, like the Bimbe and Bradbury layered targets, but its K 2 O is much lower, averaging 0.2 wt% compared to 1 wt% for the other layered targets.…”

Section: Resultsmentioning

confidence: 99%

“…The first is that, based on ChemCam observations, the composition of bedded sandstones on Bradbury Rise, for example, at the Darwin and Cooperstown waypoints ( Fig. 1 ), is nearly the same as those of the Stimson formation ( Bedford, 2019 ; Bedford et al, 2020 ), suggesting that the Stimson formation may have extended farther from Mt. Sharp than the observable portion of the Murray formation (see Williams et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

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Origin and composition of three heterolithic boulder- and cobble-bearing deposits overlying the Murray and Stimson formations, Gale Crater, Mars

Wiens

Edgett

Stack

et al. 2020

Icarus

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Heterolithic, boulder-containing, pebble-strewn surfaces occur along the lower slopes of Aeolis Mons (“Mt. Sharp”) in Gale crater, Mars. They were observed in HiRISE images acquired from orbit prior to the landing of the Curiosity rover. The rover was used to investigate three of these units named Blackfoot, Brandberg, and Bimbe between sols 1099 and 1410. These unconsolidated units overlie the lower Murray formation that forms the base of Mt. Sharp, and consist of pebbles, cobbles and boulders. Blackfoot also overlies portions of the Stimson formation, which consists of eolian sandstone that is understood to significantly postdate the dominantly lacustrine deposition of the Murray formation. Blackfoot is elliptical in shape (62 × 26 m), while Brandberg is nearly circular (50 × 55 m), and Bimbe is irregular in shape, covering about ten times the area of the other two. The largest boulders are 1.5–2.5 m in size and are interpreted to be sandstones. As seen from orbit, some boulders are light-toned and others are dark-toned. Rover-based observations show that both have the same gray appearance from the ground and their apparently different albedos in orbital observations result from relatively flat sky-facing surfaces. Chemical observations show that two clasts of fine sandstone at Bimbe have similar compositions and morphologies to nine ChemCam targets observed early in the mission, near Yellowknife Bay, including the Bathurst Inlet outcrop, and to at least one target (Pyramid Hills, Sol 692) and possibly a cap rock unit just north of Hidden Valley, locations that are several kilometers apart in distance and tens of meters in elevation. These findings may suggest the earlier existence of draping strata, like the Stimson formation, that would have overlain the current surface from Bimbe to Yellowknife Bay. Compositionally these extinct strata could be related to the Siccar Point group to which the Stimson formation belongs. Dark, massive sandstone blocks at Bimbe are chemically distinct from blocks of similar morphology at Bradbury Rise, except for a single float block, Oscar (Sol 516). Conglomerates observed along a low, sinuous ridge at Bimbe consist of matrix and clasts with compositions similar to the Stimson formation, suggesting that stream beds likely existed nearly contemporaneously with the dunes that eventually formed the Stimson formation, or that they had the same source material. In either case, they represent a later pulse of fluvial activity relative to the lakes associated with the Murray formation. These three units may be local remnants of infilled impact craters (especially circular-shaped Brandberg), decayed buttes, patches of unconsolidated fluvial deposits, or residual mass-movement debris. Their incorporation of Stimson and Murray rocks, the lack of lithification, and appearance of being erosional remnants suggest that they record erosion and deposition events that post-date the exposure of the Stimson formation.

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Mineralogical, Elemental, and Spatial Variability of Volcaniclastics in Fluvio-Coastal-Aeolian Sedimentary Systems and Their Insights for Mineral Sorting on Mars

Argadestya

Amao

Bedford

et al. 2022

Preprint

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This study investigates the mineralogical, elemental, and spatial variability from source (proximal) to sink (distal) of Merapi basalt-andesitic stratovolcano (Java, Indonesia) to better constrain volcaniclastic mineral sorting in fluvial, aeolian, and coastal environments. Merapi volcaniclastics are products of an active volcano with an ongoing quadrennial eruption, which can provide insights to constrain Mars' older and more recent volcaniclastics by focusing on anorthite, albite, and pyroxenes found on Mars' crust. We collected stream sediment samples across the Opak River that connects Merapi with the Indian Ocean and acquired Ground Penetrating Radar (GPR) surveys on Parangkusumo Shoreface and a parabolic coastal sand dune. In addition to grain size separation, all collected samples were subjected to X-Ray Diffractometer (XRD) and X-Ray Fluorescence (XRF) to quantify their mineralogical and elemental composition, respectively, like the techniques used by the Curiosity rover on Mars to investigate the geochemistry and mineralogy of geological units in the Gale crater. To interpret the geochemical analysis, we applied multivariate statistical analysis based on Principal Component Analysis (PCA) and Hierarchical Clustering of Principal Component (HCPC). The quantitative assessment shows that the provenance contains pyroclastic materials dominated by plagioclase feldspars (albite and anorthite), followed by pyroxenes (augite and enstatite), similar to the findings of basaltandesitic minerals on Mars' Gale and Gusev Crater. Mineral sorting from Merapi volcaniclastics shows a plagioclase feldspar sorting from proximal to the proximal-medial interface, fault-influenced pyroxene sorting from medial to distal, and pyroxene sorting in the aeolian-dominated sedimentary system.

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Geochemical variation in the Stimson formation of Gale crater: Provenance, mineral sorting, and a comparison with modern Martian dunes

Cited by 41 publications

References 100 publications

The Chemostratigraphy of the Murray Formation and Role of Diagenesis at Vera Rubin Ridge in Gale Crater, Mars, as Observed by the ChemCam Instrument

The Chemostratigraphy of the Murray Formation and Role of Diagenesis at Vera Rubin Ridge in Gale Crater, Mars, as Observed by the ChemCam Instrument

Origin and composition of three heterolithic boulder- and cobble-bearing deposits overlying the Murray and Stimson formations, Gale Crater, Mars

Mineralogical, Elemental, and Spatial Variability of Volcaniclastics in Fluvio-Coastal-Aeolian Sedimentary Systems and Their Insights for Mineral Sorting on Mars

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