I am searching a colleague(s) having some experience in present and past fluvial sedimentary environments coming from the erosion of ultramafic laterites (90% goethite) for exchanging experience and literature.
Dear Dominique, I am working on in-situ gossan and iron-rich terraces formed under acidic conditions. However the geological substrate is not ultramafic. I don't know if my experience will be useful for you.
Sorry for this late reaction, I have been away for fieldwork for a couple of weeks. Are the gossan and terraces you mention formed by hydrothermal activity ? or sedimentary processes ? My question is mainly related to the very special sedimentary environment created by the accumulation of almost pure detrital goethite and the possible settlement of siderophile bacteria and vascular plants in hydromorph soils. I would be happy if you could provide me some litterature on this. Many thanks for answering.
I have also recently discovered in some thin sections radial microstructures that very much resemble to microcodium (fungi ?). Has somebody some knowledge on microcodium associated with iron-rich hydromorphic soils ?
The formation of Devonian Fe-rich sediments (bioclastic limestones) we study also seem to be related to terrestrial influx + climate.
Some thin-section microphotos and our preliminary interpretations are attached.
Many thanks for answering. Although the sedimentary environments are quite different, this is a starting point. I'll consider the references you cite about iron bacteria. Best regards
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