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Radiolytical alteration of the organic matter in coal and rocks enriched in radioactive minerals
| April 20, 2023 | Filled under Com I |
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Status
active
established New Delhi, India, 2022
established New Delhi, India, 2022
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Introduction
Association of uranium with the organic matter have been studied for more than ninety years, e.g.: in bitumens (Ellsworth, 1928a, b; Parnell, 1993; England et al., 2001), bituminous coal (Kříbek et al., 2017; Sýkorová et al., 2016; Eskenazy and Velichkov, 2012), lignite (Havelcová et al. 2014; Rallakis et al., 2019), shales (Lecomte et al., 2017; Liu et al., 2020).
- Uranium minerals usually occur as inclusions of nanometer to micrometer size, often homogeneously dispersed in the organic matrix.
- Uranium derived from hydrothermal fluids concentrates in urano-organic complexes by adsorption, or by reduction of uranyl complexes; later, U may precipitate in a form of uraninite and other minerals.
- Long-lasting association of U with bitumen or coal macerals leads to damage of the organic matter. The main alteration processes of organic matter due to the presence of U comprise oxidation, biodegradation, radiolysis, and thermal degradation. During radiolysis α and β particles, and γ rays are emitted from mineral grains containing U and Th and their daughter products.
Petrographic evidences of radiolytical alteration
Unaltered/weakly altered bitumen with a group of halos
- Reflectance values in bitumen or coal increase and fluorescence intensity decreases with increase in U concentration (Breger, 1974; Parnell, 1993; Smieja-Król et al., 2009);
- Bright aureoles (circles and ellipses under microscope) – halos appearing in macerals around uranium minerals;
- Bright areas, or irregular zones, and zones forming around veins in organic matter (Jedwab, 1966; Gentry et al., 1976, Leventhal et al., 1986; Sýkorová et al., 2016; Machovič et al., 2021; Havelcová et al., 2022).
- Structural breakdown and chemical alteration of organic matter.
Studying of the morphology, structures and properties of the uraniferous organic matter in sedimentary rocks is a very important topic, mainly in geological, nuclear and environmental research fields, that are focused on radioactive materials and wastes.
Aims of the WG
- Petrological identification and definition of microscopical textures of radiolytic alteration of organic matter (bitumens, coal macerals, dispersed organic matter) with potential suitability for the ICCP Classification.
- To determine the range of (critical) uranium concentrations at which the degradation processes of organic matter begin to appear, resulting in increasing light reflectance and formation of zones around radioactive minerals.
- To determine the basic types of the bright areas around radioactive minerals: halos, bright zones around cracks and veins, and the others. On this base, the system of distinct optical structures will be developed.
References
- Breger, I.A., 1974. The role of organic matter in the accumulation of uranium: the organic geochemistry of the coal-uranium association. International Atomic Energy Agency (IAEA): IAEA.
- Ellsworth, H., 1928a. Thucholite, a remarkable primary carbon mineral from the vicinity of Parry Sound, Ontario. Am. Mineral. 13, 419-441.
- Ellsworth, H., 1928b. Thucholite and uraninite from Wallingford Mine, near Buckingham, Quebec. Am. Mineral. 13, 442-448.
- Eskenazy, G.M., Velichkov, D., 2012. Radium in Bulgarian coals. Int. J. Coal Geol. 94, 296-301.
- England, G.L., Rasmussen, B., Krapež, B., Groves, D.J., 2021. The origin of uraninite, bitumen nodules, and carbo seams in Witwatersrand gold-uranium-pyrite oree deposits based on a permo-Triassic analogue. Econ. Geol., 96, 1907-1920.
- Gentry, R.V., 1976. Radiohalos in coalified wood. New evidence relating to the time uranium introduction and coalification. Science, 194, 315-318.
- Havelcová, M., Machovič, V., Mizera, J., Sýkorová, I., Borecká, L., Kopecký, L., 2014. A multi-instrumental geochemical study of anomalous uranium enrichment in coal. J. Env. Rad. 137, 52-63.
- Havelcová, M., Machovič, V., Mizera,J., Sýkorová, I., René, M., Borecká, L., Lapčák, L., Bičáková, O., Janeček, O., Dvořák, Z., 2016. Structural changes in amber due to uranium mineralization. J. Environ. Radioactiv. 158–159, 89–101.
- Havelcová, M., Sýkorová, I., René, M., Mizera, J., Coubal, M., Machovič, V., Strunga, V., Goliáš, V., 2022. Geology and petrography of uraniferous bitumens in Permo-Carboniferous sediments (Vrchlabí, Czech Republic). Minerals, 12, 544, 1-19.
- Jedwab, J. 1966. Significance and use of optimal phenomenon in uraniferous caustobioliths. In: Coal Science, Advances in Chemistry; American Chemical Society, Washington, DC.119-132.
- Kříbek, B., Sýkorová, I., Veselovský, F., Laufek, F., Malec, J., Knésl, I., Majer, V., 2017. Trace element geochemistry of self-burning and weathering of a mineralized coal waste dump: The Novátor mine, Czech Republic. Int. J. Coal Geol., 173, 158-175.
- Lecomte, A., Cathelineau, M., Michels, R., Peiffert, C., Brouand, M., 2017. Uranium mineralization in the Alum Shale Formation (Sweden): Evolution of U-rich marine black shale from sedimentation to metamorphism. Ore Geol. Rev., 88, 71-98.
- Leventhal, J.S., Daws, T.A., Frye, J.S., 1986. Organic geochemical analysis of sedimentary organic matter associated with uranium. Appl. Geochem., 1, 241-247.
- Liu, B., Mastalerz, M., Schieber, J., Teng, J., 2020. Association of uranium with macerals in marine black shales: Insights from the Upper devonian New Albany Shale, Illinois Basin. Int. Coal Geol., 217, 103351.
- Machovič V., Havelcová M., Sýkorová I., Borecká L., Lapčák L., Mizera J., Kříbek B., Krist P., 2021. Raman mapping of coal halos induced by uranium mineral radiation. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 246, 2021; 118996.
- Parnell, J., 1993. Chemical age dating of hydrocarbon migration using uraniferous bitumens, Czech-Polish Border Region. In J. Parnell et al. (eds). Bitumens in Ore Deposits. Springer-Verlag Berlin – Heidelberg, 510-517.
- Rallakis, D., Michels, R., Brouand, M., Parize, O., Cathelineau, M., 2019. The role of organic matter on uranium precipitation in Zoovch Ovoo, Mongolia. Minerals, 9, 310.
- Smieja-Król, B., Duber, S., Rouzaud, J.-N., 2009. Multiscale organisation of organic matter associated with gold and uranium minerals in the Witwatersrand basin, South Afrika. Int. J. Coal Geol. 78, 77-88.
- Sýkorová, I., Kříbek, B., Havelcová, M., Machovič, V., Špaldoňová, A., Lapčák, L., Knésl, I., Blažek, J., 2016. Radiation- and self-ignition induced alterations of Permian uraniferous coal from the abandoned Novátor mine waste dump (Czech Republic). Int. J. Coal Geol. 168, 162–178.
- Taylor, G.H., Teichmüller, M., Davis, A., Diessel, C.F.K., Littke, R., Robert, P., 1998. Organic Petrology. Gebrüder Borntraeger, Berlin-Stuttgart.
Files
2022
WG Presentation in New Delhi, India
2023
2023 Exercise: 2023_RR_exercise_RadAltWG_text
2023_WG_RadAlt_2023_1 Round Robin_Photomicrographs_ppt
2023 RESULTS_Template_2023_RR_exercise_RadAltWG