Iron microbial communities in Belgian Frasnian carbonate mounds
Boulvain, F.; De Ridder, C.; Mamet, B.; Preat, A.; Gillan, D. (2001). Iron microbial communities in Belgian Frasnian carbonate mounds. Facies 44: 47-59. dx.doi.org/10.1007/BF02668166
In: Facies. Springer: Heidelberg; Berlin. ISSN 0172-9179; e-ISSN 1612-4820, more
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| Keywords |
Geological time > Phanerozoic > Paleozoic > Palaeozoic > Devonian > Devonian, Upper > Frasnian
Belgium, Frasnes
Marine/Coastal |
| Author keywords |
biosedimentology; carbonate mounds; iron-microbes; Belgium; devonian(Frasnian) |
| Authors | | Top |
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- Preat, A.
- Gillan, D., more
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| Abstract |
The Belgian Frasnian carbonate mounds occur in three stratigraphic levels in an overall backstepping succession. Petit-Mont and Arche Members form the famous red and grey "marble" exploited for ornamental stone since Roman times. The evolution and distribution of the facies in the mounds is thought to be associated with ecologic evolution and relative sea-level fluctuations. Iron oxides exist in five forms in the Frasnian mounds; four are undoubtedly endobiotic organized structures: (1) microstromatolites and associated forms (blisters, veils...), possibly organized in "endostromatolites''; (2) hematitic coccoids and (3) non dichotomic filaments. The filaments resemble iron bacteria of the Sphaerotilus-Leptothrix "group"; (4) networks of dichotomic filaments ascribable to fungi; (5) a red ferruginous pigment dispersed in the calcareous matrix whose distribution is related to the mound facies type. The endobiotic forms developed during the edification of the mounds, before cementation by fibrous calcite. The microbial precipitation of iron took place as long as the developing mounds were bathed by water impoverished in oxygen. |
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