Articles | Volume 23, issue 21
https://doi.org/10.5194/bg-23-7893-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-23-7893-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 Nov 2026
Research article |
| 06 Nov 2026
| 06 Nov 2026
Microscale C-O-S isotope signatures record microbial sulfate reduction in ancient deep subsurface pyrite–calcite–barite assemblages
Eric Runge
CORRESPONDING AUTHOR
Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
GeoZentrum Nordbayern, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany
Vanessa Fichtner
Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
Department of Geobiology, University of Göttingen, Göttingen, Germany
Mikael Tillberg
Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
Martin Whitehouse
Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockholm, Sweden
Henrik Drake
CORRESPONDING AUTHOR
Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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EGUsphere, https://doi.org/10.5194/egusphere-2026-3186, https://doi.org/10.5194/egusphere-2026-3186, 2026
Short summary
Short summary
Climate change is reshaping Arctic phytoplankton blooms. Using mesocosms, we tracked competition between Phaeocystis and the diatom Chaetoceros under varying silicic acid availability. Silicic acid directly determines the magnitude of the diatom bloom, but species competition is shaped by diverging responses to nutrient scarcity, grazing and viral pressure. Warming is thus likely to restructure Arctic blooms, with consequences for food webs and carbon export.
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Short summary
We investigated past microbial processes in the deep continental subsurface by stable C-O-S isotope analyses of fracture-hosted pyrite-calcite-barite assemblages. These minerals show signatures of two different pathways of microbial sulfate reduction, linked to local hydrogeochemical conditions. We further suggest that these local conditions are also crucial in controlling the preservation of microbial biosignatures in deep subsurface mineral assemblages.
We investigated past microbial processes in the deep continental subsurface by stable C-O-S...
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