Iron Mobility During Diagenesis at Vera Rubin Ridge, Gale Crater, Mars

L’Haridon, J.; Mangold, N.; Fraeman, A. A.; Johnson, J. R.; Cousin, A.; Rapin, W.; David, G.; Dehouck, E.; Sun, V. Z.; Frydenvang, J.; Gasnault, O.; Gasda, P. J.; Lanza, N.; Forni, O.; Meslin, Pierre‐Yves; Schwenzer, S. P.; Bridges, J. C.; Horgan, B.; House, Christopher H.; Salvatore, M. R.; Maurice, S.; Wiens, R. C.

doi:10.1029/2019je006299

Cited by 42 publications

(130 citation statements)

References 95 publications

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“…The lateral and vertical compositional variability of VRR compared to the underlying Murray formation and the presence of the gray/blue patches and small‐scale diagenetic features (mainly documented by ChemCam cf. L'Haridon et al, 2020) indicate enhanced mobility of elements and, hence, probable fluid flow within the ridge. The fact that VRR is compositionally within the range of the Murray encountered below the ridge also indicates that any postdepositional diagenesis/alteration did not result in wholesale changes in composition.…”

Section: Discussionmentioning

confidence: 98%

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APXS‐Derived Compositional Characteristics of Vera Rubin Ridge and Murray Formation, Gale Crater, Mars: Geochemical Implications for the Origin of the Ridge

et al. 2020

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The resistant~50 m thick Vera Rubin ridge (VRR) situated near the base of Mount Sharp, Gale crater, Mars, has been deemed a high priority science target for the Mars Science Laboratory mission. This is because of (1) its position at the base of the 5 km layered strata of Mount Sharp and (2) the detection of hematite from orbit, indicating that it could be the site of enhanced oxidation. The compositional data acquired by the Alpha Particle X-ray Spectrometer (APXS) during Curiosity's exploration of VRR help to elucidate questions pertaining to the formation of the ridge. APXS analyses indicate that VRR falls within the compositional range of underlying lacustrine mudstones, consistent with a continuation of that depositional environment and derivation from a similar provenance. Lower Fe concentrations for VRR compared to the underlying strata discounts the addition of large amounts of hematite to the strata, either as cement or as detrital input. Compositional trends are associated with VRR cross-cut stratigraphy, indicating postdepositional processes. Higher Si and Al and lower Ti, Fe, and Mn than the underlying mudstone, particularly within distinct patches of gray/blue bedrock, are consistent with the addition of Si and Al. Lateral and vertical compositional variations suggest enhanced element mobility and fluid flow (possibly via multiple events) through VRR, increasing toward the top of the ridge, consistent with the action of warm (~50-100°C), locally acidic saline fluids as inferred from the mineralogy of drilled samples. Plain Language Summary Curiosity has explored the resistant Vera Rubin ridge (VRR) at the base of Mount Sharp, Gale crater, Mars, owing to (1) its position within the 5 km layered rocks of Mount Sharp, which record changes in Mars environment through time, and (2) the detection of hematite from orbit. The Alpha Particle X-ray Spectrometer (APXS) measures the elemental composition of rocks. APXS analyses indicate that VRR has a similar composition to underlying mudstones, consistent with continued deposition in a lake. Lower iron discounts the addition of large amounts of hematite, holding together mineral grains either as cement or as detrital grains. Other elemental trends cut across layering, indicating postdepositional processes. Lateral and vertical compositional variations suggest enhanced element mobility and fluid flow (possibly via multiple events) through VRR, particularly at the top of the ridge and within gray/blue patches of bedrock, consistent with the action of warm (~50-100°C), acidic saline fluids inferred from the mineralogy of drilled samples.

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Section: Discussionmentioning

confidence: 98%

“…There are also regions of bedrock, adjacent to CaSO 4 veins, possessing finer, dark inclusions (<2 mm) surrounded by lighter gray areas (L'Haridon et al, 2020). APXS did not specifically analyze any of the areas.…”

Section: Composition Of Vrrmentioning

confidence: 99%

APXS‐Derived Compositional Characteristics of Vera Rubin Ridge and Murray Formation, Gale Crater, Mars: Geochemical Implications for the Origin of the Ridge

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“…It is composed of Journal of Geophysical Research: Planets competent gray bedrock, which contrast to the red pebbles that characterized the rest of the ridge. The gray bedrock often contains filled millimeter to centimeter-sized dark, diagenetic nodules that are frequently associated with Ca-sulfate filled veins that are ubiquitous throughout lower Mount Sharp (L'Haridon et al, 2018(L'Haridon et al, , 2020Nachon et al, 2017). MAHLI images additionally revealed the first instances of millimeter-sized crystal molds, some of which are filled and some of which are empty casts, near the red-gray color transition ( Figure 9).…”

Section: Discovery and Investigation Of "Gray Patches" (Sol 1902-1945)mentioning

confidence: 99%

“…These features could have formed during multiple, separate diagenetic events, or they could represent a related continuum of products from a single event with heterogenous geochemical conditions and fluid transport pathways. Examination of crosscutting relationships of diagenetic features suggest at least one to three distinct episodes, so a combination of the above endmember scenarios may have occurred (Horgan, n.d.;L'Haridon et al, 2020). Sun et al (2019) found the VRR-forming members, Pettegrove Point and Jura, had smaller concretions than the rest of the Murray and suggested this 10.1029/2020JE006527…”

Section: Postdepositional Processes Shaped Vrrmentioning

confidence: 99%

Evidence for a Diagenetic Origin of Vera Rubin Ridge, Gale Crater, Mars: Summary and Synthesis of Curiosity's Exploration Campaign

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This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray-colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe-rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric-related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence

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“…Journal of Geophysical Research: Planets L'Haridon et al, 2020;Tinker et al, 2019). Similar diagenetic features are common in bleached sedimentary units on Earth and form through the same dissolution/reprecipitation process as grain-size coarsening (e.g., Chan & Parry, 2000).…”

Section: Diagenesis Of Vrrmentioning

confidence: 99%

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

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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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Iron Mobility During Diagenesis at Vera Rubin Ridge, Gale Crater, Mars

Cited by 42 publications

References 95 publications

APXS‐Derived Compositional Characteristics of Vera Rubin Ridge and Murray Formation, Gale Crater, Mars: Geochemical Implications for the Origin of the Ridge

APXS‐Derived Compositional Characteristics of Vera Rubin Ridge and Murray Formation, Gale Crater, Mars: Geochemical Implications for the Origin of the Ridge

Evidence for a Diagenetic Origin of Vera Rubin Ridge, Gale Crater, Mars: Summary and Synthesis of Curiosity's Exploration Campaign

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

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