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A Mesoproterozoic iron formation

Canfield, Donald E.; Zhang, Shuichang; Wang, Huajian; Wang, Xiaomei; Zhao, Wenzhi; Su, Jin; Bjerrum, Christian J.; Haxen, Emma R. and Hammarlund, Emma U. LU (2018) In Proceedings of the National Academy of Sciences of the United States of America 115(17). p.3895-3904
Abstract

We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot... (More)

We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot rule out other pathways of Fe oxidation, iron and organic matter likely deposited to the sediment in a ratio similar to that expected for anoxygenic photosynthesis. Fe reduction was likely a dominant and efficient pathway of organic matter mineralization, as indicated by organic matter maturation by Rock Eval pyrolysis combined with carbon isotope analyses: Indeed, Fe reduction was seemingly as efficient as oxic respiration. Overall, this Mesoproterozoic-aged IF shows many similarities to Archean-aged (>2,500 Ma) banded IFs (BIFs), but with an exceptional state of preservation, allowing an unprecedented exploration of Fe-cycle dynamics in IF deposition.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Anoxygenic photosynthesis, Banded iron formation, Green sulfur bacteria, Mesoproterozoic, Oxygen
in
Proceedings of the National Academy of Sciences of the United States of America
volume
115
issue
17
pages
3895 - 3904
publisher
National Acad Sciences
external identifiers
  • scopus:85045938235
ISSN
0027-8424
DOI
10.1073/pnas.1720529115
language
English
LU publication?
yes
id
242c87e2-312c-4204-87e6-540fe9bde59b
date added to LUP
2018-05-04 08:44:04
date last changed
2018-10-03 10:37:30
@article{242c87e2-312c-4204-87e6-540fe9bde59b,
  abstract     = {<p>We describe a 1,400 million-year old (Ma) iron formation (IF) from the Xiamaling Formation of the North China Craton. We estimate this IF to have contained at least 520 gigatons of authigenic Fe, comparable in size to many IFs of the Paleoproterozoic Era (2,500–1,600 Ma). Therefore, substantial IFs formed in the time window between 1,800 and 800 Ma, where they are generally believed to have been absent. The Xiamaling IF is of exceptionally low thermal maturity, allowing the preservation of organic biomarkers and an unprecedented view of iron-cycle dynamics during IF emplacement. We identify tetramethyl aryl isoprenoid (TMAI) biomarkers linked to anoxygenic photosynthetic bacteria and thus phototrophic Fe oxidation. Although we cannot rule out other pathways of Fe oxidation, iron and organic matter likely deposited to the sediment in a ratio similar to that expected for anoxygenic photosynthesis. Fe reduction was likely a dominant and efficient pathway of organic matter mineralization, as indicated by organic matter maturation by Rock Eval pyrolysis combined with carbon isotope analyses: Indeed, Fe reduction was seemingly as efficient as oxic respiration. Overall, this Mesoproterozoic-aged IF shows many similarities to Archean-aged (&gt;2,500 Ma) banded IFs (BIFs), but with an exceptional state of preservation, allowing an unprecedented exploration of Fe-cycle dynamics in IF deposition.</p>},
  author       = {Canfield, Donald E. and Zhang, Shuichang and Wang, Huajian and Wang, Xiaomei and Zhao, Wenzhi and Su, Jin and Bjerrum, Christian J. and Haxen, Emma R. and Hammarlund, Emma U.},
  issn         = {0027-8424},
  keyword      = {Anoxygenic photosynthesis,Banded iron formation,Green sulfur bacteria,Mesoproterozoic,Oxygen},
  language     = {eng},
  month        = {04},
  number       = {17},
  pages        = {3895--3904},
  publisher    = {National Acad Sciences},
  series       = {Proceedings of the National Academy of Sciences of the United States of America},
  title        = {A Mesoproterozoic iron formation},
  url          = {http://dx.doi.org/10.1073/pnas.1720529115},
  volume       = {115},
  year         = {2018},
}