Iron microbial communities in Belgian Frasnians carbonate mounds |
| |
Authors: | Frédéric Boulvain Chantal De Ridder Bernard Mamet Alain Préat David Gillan |
| |
Institution: | (1) Géologie-Pétrologie-Géochimie, B20, Université de Liége, Sart Tilman, B-4000 Liège;(2) Biologie Marine CP160/15, Université Libre de Bruxelles, 50 av. Roosevelt, B-1050 Bruxelles;(3) Sciences de la Terre et del Environnenment CP160/02, Université Libre de Bruxelles, av. Roosevelt, B-1050 Bruxelles |
| |
Abstract: | Summary 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 theSphaerotilus-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. |
| |
Keywords: | biosedimentology carbonate mounds iron-microbes belgium devonian (Frasnian) |
本文献已被 SpringerLink 等数据库收录! |
|