Microbial activity records in Marinoan Snowball Earth postglacial transition layers connecting diamictite with cap carbonate (Otavi Group, NW-Namibia)
- Author(s)
- Ildiko Gyollai, Marta Polgari, Krisztian Fintor, Elemer Pal-Molnar, Friedrich Popp, Christian Koeberl
- Abstract
This study concerns the microbial mat formation in postglacial layers of the Marinoan Snowball Earth glaciation. A high resolu-
tion investigation was carried out on the transition layers of Ghaub to Maieberg Formation (start of Keilberg Member) of the Otavi
Group in NW-Namibia (Neoproterozoic). Macroscopic characterization, optical rock microscopy, XRD mineralogy, Raman spectros-
copy investigations were done and geochemical (major and trace element content) as well as carbonate carbon isotopic data
were collected. Three types of microbial contributions were determined: (1) primary, synsedimentary Fe-rich biomats; (2) secon-
dary biomats from biodegradation of Fe-bearing minerals (pyrite, chlorite); and (3) pseudo-secondary structures coating on clasts.
These microbial mats of iron-oxidizing bacteria consumed iron from different sources, such as hydrothermal solutions or iron-
bearing minerals. On the basis of the morphology of Fe-biomats, and the mineralogical and geochemical signatures, we suggest
that the Marinoan postglacial transition layers (Ghaub-Maieberg boundary) formed under neutral, suboxic conditions in brackish
water at the studied locality.- Organisation(s)
- Department of Geology, Department of Lithospheric Research
- External organisation(s)
- Eszterházy Károly University of Applied Sciences, University of Szeged, Naturhistorisches Museum Wien (NHM), University of Vienna, Hungarian Academy of Sciences
- Journal
- Austrian Journal of Earth Sciences
- Volume
- 110
- Pages
- 4-20
- No. of pages
- 17
- ISSN
- 2072-7151
- Publication date
- 2017
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105105 Geochemistry, 105121 Sedimentology
- Keywords
- ASJC Scopus subject areas
- Geology, Palaeontology, Stratigraphy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/96af2b60-bf44-491e-afaa-6fc8c94a9b0e