Pelagic barite precipitation at micromolar ambient sulfate

Geochemical analyses of sedimentary barites (barium sulfates) in the geological record have yielded fundamental insights into the chemistry of the Archean environment and evolutionary origin of microbial metabolisms. However, the question of how barites were able to precipitate from a contemporary o...

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Bibliographic Details
Published in:Nature communications 2017-11, Vol.8 (1), p.1342-11, Article 1342
Main Authors: Horner, Tristan J., Pryer, Helena V., Nielsen, Sune G., Crockford, Peter W., Gauglitz, Julia M., Wing, Boswell A., Ricketts, Richard D.
Format: Article
Language:English
Subjects:
704/106/2738
704/172/169/209
704/286
704/47/4112
Barite
Barium
Geochemistry
Geology
Humanities and Social Sciences
Microenvironments
Microorganisms
multidisciplinary
Organic matter
Precipitation
Remineralization
Science
Science (multidisciplinary)
Sedimentation
Sulfates
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Summary:Geochemical analyses of sedimentary barites (barium sulfates) in the geological record have yielded fundamental insights into the chemistry of the Archean environment and evolutionary origin of microbial metabolisms. However, the question of how barites were able to precipitate from a contemporary ocean that contained only trace amounts of sulfate remains controversial. Here we report dissolved and particulate multi-element and barium-isotopic data from Lake Superior that evidence pelagic barite precipitation at micromolar ambient sulfate. These pelagic barites likely precipitate within particle-associated microenvironments supplied with additional barium and sulfate ions derived from heterotrophic remineralization of organic matter. If active during the Archean, pelagic precipitation and subsequent sedimentation may account for the genesis of enigmatic barite deposits. Indeed, barium-isotopic analyses of barites from the Paleoarchean Dresser Formation are consistent with a pelagic mechanism of precipitation, which altogether offers a new paradigm for interpreting the temporal occurrence of barites in the geological record. The question of how significant barite deposits were able to form from early Earth’s low-sulfate seas remains controversial. Here, the authors show pelagic barite precipitation within a strongly barite-undersaturated ecosystem, highlighting the importance of particle-associated microenvironments.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-017-01229-5