Multiple precursors of secondary mineralogical assemblages in <scp>CM</scp> chondrites

Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel G.; Delon, Rémi; Gounelle, M.

doi:10.1111/maps.12625

Cited by 46 publications

(80 citation statements)

References 60 publications

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“…Although most TCIs occur as irregular anhedral or subhedral grains 30–40 μm in size, some are euhedral, characteristic of anhydrous silicate pseudomorphism (Pignatelli et al. ). In section 3788‐1, we performed 190 microprobe measurements over 40 dispersed TCIs: 28 ( n = 142) in lithology A and 12 ( n = 48) in lithology C. Following the criteria defined by Pignatelli et al.…”

Section: Resultsmentioning

confidence: 99%

“…As in Pignatelli et al. (), TCIs with S > 10 wt% and Si < 5 wt% were considered tochilinite, those with Si > 7 wt% and S < 5 wt% were regarded as cronstedtite, and others were assigned as intermediate.…”

Section: Methodsmentioning

confidence: 99%

“…; Pignatelli et al. , , ; Van Kooten et al. ), and oxygen isotopes are a powerful tool for constraining the physicochemical conditions (T, W / R , pH, etc.)…”

Section: Introductionmentioning

confidence: 99%

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Testing the genetic relationship between fluid alteration and brecciation in CM chondrites

Verdier-Paoletti

Marrocchi

Vacher

et al. 2019

Meteorit & Planetary Scien

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Boriskino is a poorly studied CM chondrite with numerous millimeter‐ to centimeter‐scale clasts exhibiting sharp boundaries. Clast textures and mineralogies attest to diverse geological histories with various degrees of aqueous alteration. We conducted a petrographic, chemical, and isotopic study on each clast type of the breccia to investigate if there exists a genetic link between brecciation and aqueous alteration, and to determine the controlling parameter of the extent of alteration. Boriskino is dominated by CM2 clasts for which no specific petrographic type could be assigned based on the chemical compositions and modal abundances of constituents. One clast stands out and is identified as a CM1 lithology, owing to its lack of anhydrous silicates and its overall abundance of dolomite‐like carbonates and acicular iron sulfides. We observe that alteration phases near clast boundaries exhibit foliation features, suggesting that brecciation postdated aqueous alteration. We measured the O‐isotopic composition of Ca‐carbonates and dolomite‐like carbonates to determine their precipitation temperatures following the methodology of Verdier‐Paoletti et al. (2017). Both types of carbonates yield similar ranges of precipitation temperatures independent of clast lithology, ranging from −13.9 ± 22.4 (2σ) to 166.5 ± 47.3 °C, precluding that temperature alone accounts for the differences between the CM1 and CM2 lithologies. Instead, we suggest that initial water/rock ratios of 0.75 and 0.61 for the CM1 and CM2 clasts, respectively, might control the extent of aqueous alteration. Based on these estimates, we suggest that Boriskino clasts originated from a single parent body with heterogeneous distribution of water either due to local differences in the material permeability or in the initial content of ice available. These conditions would have produced microenvironments with differing geochemical conditions thus leading to a range of degrees of aqueous alteration.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Testing the genetic relationship between fluid alteration and brecciation in CM chondrites

Verdier-Paoletti

Marrocchi

Vacher

et al. 2019

Meteorit & Planetary Scien

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“…; Rubin ; Pignatelli et al. , ; Vacher et al. ), our thin section presents variable degrees of alteration on both sides characterized by significant differences in the abundance of Fe‐Ni metal beads.…”

Section: Methodsmentioning

confidence: 65%

“…In addition, aqueous alteration onto asteroidal parent bodies of meteorites mainly took place within geochemical microenvironments that were not connected together (Le Guillou and Brearley ; Pignatelli et al. ). This is due to the low permeability of chondrites (Bland et al.…”

Section: Introductionmentioning

confidence: 99%

Primordial heavy noble gases in the pristine Paris carbonaceous chondrite

Bekaert

Marrocchi

Meshik

et al. 2018

Meteorit & Planetary Scien

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The Paris carbonaceous chondrite represents the most pristine carbonaceous chondrite, providing a unique opportunity to investigate the composition of early solar system materials prior to the onset of significant aqueous alteration. A dual origin (namely from the inner and outer solar system) has been demonstrated for water in the Paris meteorite parent body (Piani et al. 2018 ). Here, we aim to evaluate the contribution of outer solar system (cometary‐like) water ice to the inner solar system water ice using Xe isotopes. We report Ar, Kr, and high‐precision Xe isotopic measurements within bulk CM 2.9 and CM 2.7 fragments, as well as Ne, Ar, Kr, and Xe isotope compositions of the insoluble organic matter ( IOM ). Noble gas signatures are similar to chondritic phase Q with no evidence for a cometary‐like Xe component. Small excesses in the heavy Xe isotopes relative to phase Q within bulk samples are attributed to contributions from presolar materials. CM 2.7 fragments have lower Ar/Xe relative to more pristine CM 2.9 fragments, with no systematic difference in Xe contents. We conclude that Kr and Xe were little affected by aqueous alteration, in agreement with (1) minor degrees of alteration and (2) no significant differences in the chemical signature of organic matter in CM 2.7 and CM 2.9 areas (Vinogradoff et al. 2017 ). Xenon contents in the IOM are larger than previously published data of Xe in chondritic IOM , in line with the Xe component in Paris being pristine and preserved from Xe loss during aqueous alteration/thermal metamorphism.

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The Effect of the Starting Mineralogical Mixture on the Nature of Fe-Serpentines Obtained during Hydrothermal Synthesis AT 90°C

Pignatelli¹,

Mosser‐Ruck²,

Mugnaioli³

et al. 2020

Clays and clay miner.

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The formation conditions and stability fields of Fe-serpentines are still poorly understood in both terrestrial (natural or anthropic) and extraterrestrial environments. Knowledge of the effects of physical-chemical parameters on compositional and structural features of Fe-serpentines is lacking, and only a few thermodynamic parameters of these minerals are available in the literature. To fill these gaps, the synthesis of these minerals, while controlling all the physicochemical experimental parameters, was undertaken. Two hydrothermal syntheses were carried out at 90°C to investigate the effect of two different starting mineralogical mixtures on the nature of Fe-serpentines. The run products were identified by several analytical techniques (powder X-ray diffraction, transmission, and scanning electron microscopy). Berthierine crystals were synthesized from a starting mixture of kaolinite and metal iron. The berthierines synthesized show different morphologies and iron contents (~3–38 at.%). From a starting mineralogical mixture composed of quartz and metal iron, cronstedtite crystallizes. Most of the crystals are 1M polytypes. Magnetite is always associated with both berthierine and cronstedtite. Lepidocrocite was observed only in the experiment with kaolinite. These experimental results demonstrated that Fe enrichment in serpentines depends on the silicate precursor (kaolinite or quartz) of the starting mixture. The results are also in agreement with the geochemical equilibrium predicted by thermodynamic modeling, i.e. the formation of berthierine and cronstedtite in association with magnetite at the expense of metal iron and silicates.

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Multiple precursors of secondary mineralogical assemblages in CM chondrites

Cited by 46 publications

References 60 publications

Testing the genetic relationship between fluid alteration and brecciation in CM chondrites

Testing the genetic relationship between fluid alteration and brecciation in CM chondrites

Primordial heavy noble gases in the pristine Paris carbonaceous chondrite

The Effect of the Starting Mineralogical Mixture on the Nature of Fe-Serpentines Obtained during Hydrothermal Synthesis AT 90°C

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