Iron–clay interactions: Detailed study of the mineralogical transformation of claystone with emphasis on the formation of iron-rich T–O phyllosilicates in a step-by-step cooling experiment from 90 °C to 40 °C

Pignatelli, Isabella; Bourdelle, Franck; Bartier, Danièle; Mosser‐Ruck, Régine; Truche, Laurent; Mugnaioli, Enrico; Michau, Nicolas

doi:10.1016/j.chemgeo.2014.08.010

Cited by 37 publications

(25 citation statements)

References 36 publications

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“…In addition, experiments and thermodynamic modeling have shown that cronstedtite crystals form under specific conditions: pH = 7–8, log f O 2 ≈ –65 to –60 (estimated from the measured Si concentrations in solutions from experiment GOI and the calculated stability field of cronstedtite at 80 °C from Pignatelli et al. ; Fig. ), and below 100 °C because the stability field of cronstedtite decreases with increasing temperature (Fig.…”

Section: Discussionmentioning

confidence: 98%

“…The stability fields of cronstedtite, greenalite, hematite, and magnetite in log (Si[aq]) versus f (O2) phase diagrams at 80°C (solid black line and blue shaded field), 100°C, and 150°C (dotted lines) from Pignatelli et al (). The vertical dashed black line corresponds to the Si concentration measured in the run solution of S‐free experiment GOI and the red shaded area represents the range of Si concentrations measured in the solutions of S‐bearing experiment GOIS.…”

Section: Discussionmentioning

confidence: 99%

“…) and (2) cronstedtite deduced from hydrothermal experiments and thermodynamic data (i.e., 50 ≤ T ≤ 120 °C; Pignatelli et al. , ; Zolotov ).…”

Section: Discussionmentioning

confidence: 99%

“…, ), whereas cronstedtite forms under less reduced conditions than tochilinite due to the presence of Fe 3+ (Pignatelli et al. ), in circumneutral pH environments (Pignatelli et al. ), and below 120 °C (Lantenois et al.…”

Section: Discussionmentioning

confidence: 99%

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Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments

Vacher

Truche

Fauré

et al. 2019

Meteorit & Planetary Scien

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Tochilinite/cronstedtite intergrowths are commonly observed as alteration products in CM chondrite matrices, but the conditions under which they formed are still largely underconstrained due to their scarcity in terrestrial environments. Here, we report low temperature (80 °C) anoxic hydrothermal experiments using starting assemblages similar to the constituents of the matrices of the most pristine CM chondrite and S‐rich and S‐free fluids. Cronstedtite crystals formed only in S‐free experiments under circumneutral conditions with the highest Fe/Si ratios. Fe‐rich tochilinite with chemical and structural characteristics similar to chondritic tochilinite was observed in S‐bearing experiments. We observed a positive correlation between the Mg content in the hydroxide layer of synthetic tochilinite and temperature, suggesting that the composition of tochilinite is a proxy for the alteration temperature in CM chondrites. Using this relation, we estimate the mean precipitation temperatures of tochilinite to be 120–160 °C for CM chondrites. Given the different temperature ranges of tochilinite and cronstedtite in our experiments, we propose that Fe‐rich tochilinite crystals resulted from the alteration of metal beads under S‐bearing alkaline conditions at T = 120–160 °C followed by cronstedtite crystals formed by the reaction of matrix amorphous silicates, metal beads, and water at a low temperature (50–120 °C).

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

“…) and (2) cronstedtite deduced from hydrothermal experiments and thermodynamic data (i.e., 50 ≤ T ≤ 120 °C; Pignatelli et al. , ; Zolotov ).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments

Vacher

Truche

Fauré

et al. 2019

Meteorit & Planetary Scien

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“…Thermodynamic calculations and experimental observations indicate that the stability field of cronstedtite decreases with increasing temperature and cronstedtite is unstable at T > 100 °C (Schulte and Shock ; McAlister and Kettler ; Pignatelli et al. ; Zolotov ). However, a lower limit of 50 °C has recently been determined experimentally (Pignatelli et al.…”

Section: Discussionmentioning

confidence: 99%

Multiple precursors of secondary mineralogical assemblages in CM chondrites

Pignatelli

Marrocchi

Vacher

et al. 2016

Meteorit & Planetary Scien

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We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type‐I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe‐Ni metal beads, thus confirming kamacite as the precursor of type‐I TCIs. In contrast, type‐II TCIs are characterized by complex compositional zoning composed of three different Fe‐bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type‐II TCIs present well‐developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type‐II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type‐I and type‐II TCIs. In addition, the complex chemical zoning observed within type‐II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe‐ and S‐rich fluids; (2) S‐poor and Fe‐ and Si‐rich fluids; and (3) S‐ and Si‐poor, Fe‐rich fluids. The presence of unaltered silicates in close association with euhedral type‐II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg‐bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

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Investigation of steel corrosion in MX80 bentonite at 120°C

Lotz

Carrière

Bataillon

et al. 2020

Materials & Corrosion

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Corrosion experiments were performed on two metallic substrates, a ferritic–pearlitic steel (P285NH) and a ferritic one (Armco), in silicate environment during 30 days at 120°C. Corrosion products were characterized in terms of morphology (scanning electron microscope and transmission electron microscopy), composition (energydispersive X‐ray spectroscopy) and structure (µ‐Raman, selected area electron diffraction, X‐ray absorption near edge structure). Results show a nanometric inner layer made of compact and adherent nanocrystallized magnetite with, locally a thickness up to several micrometers due to the metal microstructure. An outer layer of Fe‐rich phyllosilicate, smectite and serpentine, more porous than the inner one and poorly adherent is observed around both the samples.

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Iron–clay interactions: Detailed study of the mineralogical transformation of claystone with emphasis on the formation of iron-rich T–O phyllosilicates in a step-by-step cooling experiment from 90 °C to 40 °C

Cited by 37 publications

References 36 publications

Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments

Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments

Multiple precursors of secondary mineralogical assemblages in CM chondrites

Investigation of steel corrosion in MX80 bentonite at 120°C

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