Uniaxial Compressive Strengths of Rocks Drilled at Gale Crater, Mars

Peters, G. H.; Carey, E. M.; Anderson, Robert C.; Abbey, W. J.; Kinnett, R.; Watkins, J. A.; Schemel, Madeline; Lashore, Michael; Chasek, M. D.; Green, W.; Vasavada, A. R.

doi:10.1002/2017gl075965

Cited by 26 publications

(33 citation statements)

References 25 publications

(29 reference statements)

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“…Diagenetic cements have the potential to significantly increase the strength of bedrock, especially in the case of sandstones, due to their higher permeability compared to mudstones (e.g., Cook et al, 2014; Marshall & Roering, 2014). Across the Murray formation, rock strength does not exhibit a clear correlation with mineralogy or chemical compositions, but cementing agents that could affect strength may include hematite, Ca sulfate, and/or phyllosilicates (Peters et al, 2018). On VRR, the diversity of diagenetic events may have affected the strength of the rocks in other ways.…”

Section: Discussionmentioning

confidence: 99%

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

et al. 2020

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Images from the Mars Science Laboratory (MSL) mission of lacustrine sedimentary rocks of Vera Rubin ridge on "Mt. Sharp" in Gale crater, Mars, have shown stark color variations from red to purple to gray. These color differences crosscut stratigraphy and are likely due to diagenetic alteration of the sediments after deposition. However, the chemistry and timing of these fluid interactions is unclear. Determining how diagenetic processes may have modified chemical and mineralogical signatures of ancient Martian environments is critical for understanding the past habitability of Mars and achieving the goals of the MSL mission. Here we use visible/near-infrared spectra from Mastcam and ChemCam to determine the mineralogical origins of color variations in the ridge. Color variations are consistent with changes in spectral properties related to the crystallinity, grain size, and texture of hematite. Coarse-grained gray hematite spectrally dominates in the gray patches and is present in the purple areas, while nanophase and fine-grained red crystalline hematite are present and spectrally dominate in the red and purple areas. We hypothesize that these differences were caused by grain-size coarsening of hematite by diagenetic fluids, as observed in terrestrial analogs. In this model, early primary reddening by oxidizing fluids near the surface was followed during or after burial by bleaching to form the gray patches, possibly with limited secondary reddening after exhumation. Diagenetic alteration may have diminished the preservation of biosignatures and changed the composition of the sediments, making it more difficult to interpret how conditions evolved in the paleolake over time. Plain Language Summary Sedimentary rocks found in deserts on Earth often exhibit striking color differences from red and purple to white, which are caused by groundwater dissolving and reprecipitating iron oxides within the rocks. NASA's Mars Science Laboratory (MSL) mission has observed similar color differences on Mars within the sedimentary rocks of Vera Rubin ridge in Gale crater, which were laid down in an ancient lake. We use color images and spectral data from the Mastcam cameras on MSL to investigate the origin of these color differences and find that they are consistent with changes in iron oxides through the ridge. This variation in iron oxides suggests that groundwater flowed through and altered these rocks multiple times before and after they were buried by later sediments. The MSL mission has shown that habitable lake environments once existed in Gale crater, through detections of the building blocks of life, including organic molecules, and by showing that conditions that existed in the lake were clement for life. However, later alteration by groundwater may have diminished the preservation of organics and changed the composition of these rocks, making it more difficult to interpret the details of how conditions evolved in the lake over time.

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Section: Discussionmentioning

confidence: 99%

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

et al. 2020

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“…The observations discussed in this paper (supporting information Tables S1 and S2) were acquired on targets that were either successfully drilled or attempted to be drilled using the rover's Sample Acquisition, Processing, and Handling system (SA/SPaH; Anderson et al, 2012). Information about the hardness of the rocks can be obtained from the ancillary data of the drill (Peters et al, 2018). Under the original drilling protocol, loading of the drill bit was maintained by the drill's translation mechanism, which moves along a linear path independently of a set of stabilizers.…”

Section: Data Sets and Methodsmentioning

confidence: 99%

“…The Duluth and VRR drill targets are not included because they do not have quantitative strengths available. The x-axis error bars represent the range of possible strengths listed inPeters et al, (2018) 5.5 Laboratory Mixture Spectral ParametersFigure 15presents spectra of the laboratory mixtures(Table 2)and nontronite endmember convolved to Mastcam filter wavelengths to demonstrate variations in band depths and band minima of the near-IR absorption feature as a function of different mixtures. Mixtures with 5…”

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Spectral, Compositional, and Physical Properties of the Upper Murray Formation and Vera Rubin Ridge, Gale Crater, Mars

et al. 2020

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“…This is probably a safe assumption. Where measured, in-place Mars clastic rock strength is similar to adobe bricks or weak concrete, not to loose sand (Thomson et al 2013, Peters et al 2018. Although shorter valley formation durations are possible if the Mars valley networks were cut into loose, fine-grained sediment (Rosenberg & Head 2015), that set-up does not match in-place measurements of Mars rock strength.…”

Section: N × τ = Cumulative Wet Years During Valley-network-forming Cmentioning

confidence: 95%

Geologic Constraints on Early Mars Climate

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2019

Space Sci Rev

108

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Early Mars climate research has well-defined goals (Mars Exploration Program Analysis Group 2018). Achieving these goals requires geologists and climate modelers to coordinate. Coordination is easier if results are expressed in terms of well-defined parameters. Key parameters include the following quantitative geologic constraints.(1) Cumulative post-3.4 Ga precipitation-sourced water runoff in some places exceeded 1 km column. (2) There is no single Early Mars climate problem: the traces of ≥2 riverforming periods are seen. Relative to rivers that formed earlier in Mars history, rivers that formed later in Mars history are found preferentially at lower elevations, and show a stronger dependence on latitude. (3) The duration of the longest individual river-forming climate was >(10 2 -10 3 ) yr, based on paleolake hydrology. (4) Peak runoff production was >0.1 mm/hr. However, (5) peak runoff production was intermittent, sustained (in a given catchment) for only <10% of the duration of river-forming climates. (6) The cumulative number of wet years during the valley-network-forming period was >10 5 yr. (7) Post-Noachian light-toned, layered sedimentary rocks took >10 7 yr to accumulate. However, (8) an "average" place on Mars saw water for <10 7 yr after the Noachian, suggesting that the river-forming climates were interspersed with long globally-dry intervals. (9) Geologic proxies for Early Mars atmospheric pressure indicate pressure was not less than 0.012 bar but not much more than 1 bar. A truth table of these geologic constraints versus currently published climate models shows that the late persistence of river-forming climates, combined with the long duration of individual lake-forming climates, is a challenge for most models. Kraal, Erin R.; Asphaug, Erik; Moore, Jeffery M.; Howard, Alan; Bredt, Adam, 2008a, Catalogue of large alluvial fans in martian impact craters, Icarus, 194, 1, 101-110. Kraal, Erin R.; van Dijk, Maurits; Postma, George; Kleinhans, Maarten G., 2008b, Martian stepped-delta formation by rapid water release, Nature, 451, 7181, 973-976.Kurahashi-Nakamura, Takasumi; Tajika, Eiichi, 2006, Atmospheric collapse and transport of carbon dioxide into the subsurface on early Mars, Geophys. Res. Lett., 33, L18205.

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Uniaxial Compressive Strengths of Rocks Drilled at Gale Crater, Mars

Cited by 26 publications

References 25 publications

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

Spectral, Compositional, and Physical Properties of the Upper Murray Formation and Vera Rubin Ridge, Gale Crater, Mars

Geologic Constraints on Early Mars Climate

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