Decoupling of Neoarchean sulfur sources recorded in Algoma-type banded iron formation.

Diekrup, David, Hannington, Mark D., Strauss, Harald and Ginley, Stephen J. (2018) Decoupling of Neoarchean sulfur sources recorded in Algoma-type banded iron formation. Earth and Planetary Science Letters, 489 . pp. 1-7. DOI 10.1016/j.epsl.2018.02.022.

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Supplementary data:

Abstract

Highlights

• The genetic model for Algoma-type BIF is modified taking into account S-MIF results.
• Metal and sulfur sources are decoupled and reflect diverse microbial metabolisms.
• Sulfur deposited with oxide-facies BIF is mostly atmospheric in origin.
• Little juvenile sulfur is found, despite the proximity to volcanic sources.

Abstract

Neoarchean Algoma-type banded iron formations (BIFs) are widely viewed as direct chemical precipitates from proximal volcanic–hydrothermal vents. However, a systematic multiple sulfur isotope study of oxide-facies BIF from a type locality in the ca. 2.74 Ga Temagami greenstone belt reveals mainly bacterial turnover of atmospheric elemental sulfur in the host basin rather than deposition of hydrothermally cycled seawater sulfate or sulfur from direct volcanic input. Trace amounts of chromium reducible sulfur that were extracted for quadruple sulfur isotope (32S–33S–34S–36S) analysis record the previously known mass-independent fractionation of volcanic SO2 in the Archean atmosphere (S-MIF) and biological sulfur cycling but only minor contributions from juvenile sulfur, despite the proximity of volcanic sources. We show that the dominant bacterial metabolisms were iron reduction and sulfur disproportionation, and not sulfate reduction, consistent with limited availability of organic matter and the abundant ferric iron deposited as Fe(OH)3. That sulfur contained in the BIF was not a direct volcanic–hydrothermal input, as expected, changes the view of an important archive of the Neoarchean sulfur cycle in which the available sulfur pools were strongly decoupled and only species produced photochemically under anoxic atmospheric conditions were deposited in the BIF-forming environment.

Document Type: Article
Keywords: banded iron formation, multiple sulfur isotopes, Neoarchean, hydrothermal, sulfur disproportionation, marine paleoenvironment
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS > Marine Mineralische Rohstoffe
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2018.02.022
ISSN: 0012-821X
Date Deposited: 12 Mar 2018 09:55
Last Modified: 06 Feb 2020 09:05
URI: http://oceanrep.geomar.de/id/eprint/42218

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