Alteration of fossil-bearing shale (Autun Basin, France; Permian), part I: Characterizing iron speciation and its vulnerability to weathering by combined use of Mössbauer spectroscopy, X-ray diffraction, porosimetry and permeability measurements

Odin, G.S.; Cabaret, Thomas; Mertz, Jean‐Didier; Menéndez, Beatriz; Etienne, Laetitia; Wattiaux, Alain; Rouchon, Véronique

doi:10.1016/j.annpal.2015.01.002

Cited by 7 publications

(20 citation statements)

References 24 publications

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“…As reported by others authors (Tuttle et al, 2014), these rust deposits occurred laterally, depending on the shale bedding plans. This is in-line with previous work (Odin et al, 2015a(Odin et al, , 2015b showing that (i) the shale was transversally poorly permeable to water and impermeable to air and (ii) sulfur was mostly present as organic and inorganic sulfide. Also black shale samples were selected for artificial ageing, as they were believed to have been relatively spared from weathering.…”

Section: Samples Used For Artificial Ageing Experimentssupporting

confidence: 92%

“…The shale fraction of this specimen was analyzed (Odin et al, 2015a(Odin et al, , 2015b, showing that matrix-sulfur is almost entirely oxidized as sulfate (gypsum and belonging to jarosite group). In contrast, vitrinite is not much affected by oxidation.…”

Section: "Naturally" Damaged Samplesmentioning

confidence: 99%

“…On the Surmoulin samples, large efflorescence of calcium sulfate was growing upon artificial ageing. Yet these samples initially contain a large proportion of calcium carbonate (dolomite) but no pyrite (Odin et al, 2015a). Occurrence of gypsum may, in this case, be explained by oxidation of other sulfur-bearing phases, such as organic sulfides.…”

Section: Gypsum Efflorescencementioning

confidence: 99%

“…This work is organized in three parts. The first two are dedicated to the characterization of sulfur-and iron-bearing compounds present in the shale matrix (Odin et al, 2015a(Odin et al, , 2015b and led to the conclusion that these compounds could not account for the large efflorescence noticed nearby the fossil line.…”

Section: Introductionmentioning

confidence: 99%

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Alterations of fossil-bearing shale (Autun, France; Permian), part III: Framboidal pyrite and sulfur as the main cause of efflorescence

Odin

Belhadj

Cabaret

et al. 2016

Annales de Paléontologie

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International audienceFossil-bearing shale specimens that include sulfides are chemically reactive and sometimes also mechanically fragile. This decay is provoked by iron sulfate efflorescence resulting from the oxidation of sulfide compounds. The processes underlying these degradations are poorly known, thus impeding the elaboration of curative or preventive treatments. The present contribution aims to identify the origin of museum specimen alterations. It focuses on the Flouest collection housed at the Muséum national d’Histoire naturelle (MNHN, Paris, France) and originating from the Autun Basin (Saône-et-Loire, France; Permian). To evaluate the alteration of MNHN specimens, it appeared necessary to compare their composition with that of unaltered shale so as to identify chemical changes occurring during ageing. Therefore new material was collected in the Autun Basin, among others on the locality of Muse that corresponds to the same lithostratigraphic unit than that of the MNHN specimens. This work is divided in three parts. The two first, presented elsewhere, deal with the composition of the shale matrices and led to the conclusion that these matrices could not account for the large iron(II) sulfate efflorescence provoking damage on the MNHN specimens. The last part of this work, presented here, focus on artificial ageing experiments performed on new shale material. Most of the alterations observed on artificially aged samples correspond to dispersed crystals of calcium sulfate (gypsum). Similar crystals may be found on MNHN specimens, but they are relatively few and sporadically distributed. They are thus considered as damage of secondary importance with respect to iron sulfate efflorescence. These latter could be reproduced on three samples only (upon the 142 aged samples). They were also found on a coprolite and on a wood remain that had got severely damaged in ambient conditions within a few months after their excavation. On all these samples iron sulfate had grown on brownish layers consisting in crystals of framboidal pyrite (1 to 3 μm) and eventually sulfur (20 to 50 μm). These brownish layers are associated to thin maceral layers probably because of bacterial activity: during fossil diagenesis, bacteria need organic matter for their metabolism to produce hydrogen sulfide, a precursor of sedimentary pyrite formation. Most of the damaged specimens of the Flouest collection show as well a thin maceral layer nearby iron(II) sulfate efflorescence. On one of them, this layer is particularly thick. It corresponds to vitrinite and shows in some areas a brownish aspect. The topology of this surface (observed with scanning electron microscopy) shows numerous small holes (< 2 μm) and large holes (10–20 μm). This morphology is compatible with a former occurrence of isolated grains and aggregates of framboidal pyrite. These observations suggest that iron sulfate efflorescence was provoked by the oxidation of framboidal pyrite forming deposits on maceral layers. Because of their brownish aspect, they can easily ...

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Section: Samples Used For Artificial Ageing Experimentssupporting

confidence: 92%

Section: "Naturally" Damaged Samplesmentioning

confidence: 99%

Section: Gypsum Efflorescencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alterations of fossil-bearing shale (Autun, France; Permian), part III: Framboidal pyrite and sulfur as the main cause of efflorescence

Odin

Belhadj

Cabaret

et al. 2016

Annales de Paléontologie

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“…X-ray diffraction is a widely used method in petro geology field to identify, analyze and measure the solid phase, which can be divided into two types of qualitative and quantitative analysis (Odin et al, 2015).…”

Section: X-ray Diffractionmentioning

confidence: 99%

Study of Pore Structure of Gas Shale with Low-Field NMR: Examples from the Longmaxi Formation, Southern Sichuan Basin, China

Chen

Zhang

2015

All Days

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Pore structure of gas shale which possesses lots of nanopores is complex. NMR measurement can not only obtain accurate sample parameters but also provide an approach to quantitatively study pore structure. This paper Integrates NMR, mercury injection, nitrogen adsorption and X-ray diffraction to analyze the relationships of pore structure, surface to volume ratio and mineral components.Both nitrogen adsorption and mercury-injection have some limitations in characterizating of pore structure of gas shale. In this paper we integrate pore size distribution curve of nitrogen adsorption and mercury-injection. Comparison and analyses of NMR T2 spectra and the integrated pore size distribution curve calculate NMR pore size distribution. Capillary pressure curve is constructed based on NMR T2 spectra for quantitatively studying pore structure of gas shale. The diagrams of relationship between characteristic parameters of pore structure, surface to volume ratio and mineral components such as clay minerals, pyrite and TOC are established.NMR study has been implemented on 15 samples from Longmaxi formation. The results show the porosity range from 2.24% to 5.76%. The NMR pore size distribution curves is more precise than the curves that calculated only according to nitrogen adsorption or mercury-injection. Calculating separation coefficient, skewness, structure coefficient, median pressure and other parameters from constructed capillary pressure curves indicate high threshold pressure, poor connectivity, and complex pore size distribution. Porosity has a positive correlation with clay mineral content, TOC, pyrite. Most of surface to volume ratio and pore volume are provided by micropores and mesopores.Using integration pore size distribution curve of nitrogen adsorption and mercury-injection to calculate parameter of NMR pore size distribution is a more exact approach than only using nitrogen adsorption or mercury-injection. Capillary pressure curve constructed by NMR T2 spectra can provide information of micropores and mesopores which mercury-injection cannot correctly characterize.

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Reconsidering Carboniferous–Permian continental paleoenvironments in eastern equatorial Pangea: facies and sequence stratigraphy investigations in the Autun Basin (France)

Mercuzot

Bourquin

Pellenard

et al. 2022

Int J Earth Sci (Geol Rundsch)

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Alteration of fossil-bearing shale (Autun Basin, France; Permian), part I: Characterizing iron speciation and its vulnerability to weathering by combined use of Mössbauer spectroscopy, X-ray diffraction, porosimetry and permeability measurements

Cited by 7 publications

References 24 publications

Alterations of fossil-bearing shale (Autun, France; Permian), part III: Framboidal pyrite and sulfur as the main cause of efflorescence

Alterations of fossil-bearing shale (Autun, France; Permian), part III: Framboidal pyrite and sulfur as the main cause of efflorescence

Study of Pore Structure of Gas Shale with Low-Field NMR: Examples from the Longmaxi Formation, Southern Sichuan Basin, China

Reconsidering Carboniferous–Permian continental paleoenvironments in eastern equatorial Pangea: facies and sequence stratigraphy investigations in the Autun Basin (France)

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