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Biogenicity of an Early Quaternary iron formation, Milos Island, Greece

Fru, E. Chi; Ivarsson, M.; Kilias, S. P.; Frings, Patrick LU ; Hemmingsson, C.; Broman, C.; Bengtson, S. and Chatzitheodoridis, E. (2015) In Geobiology 13(3). p.225-244
Abstract
A 2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a 5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk C-13 isotopic compositions lower than -25 parts per thousand provide evidence... (More)
A 2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a 5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk C-13 isotopic compositions lower than -25 parts per thousand provide evidence for biological contribution by the Calvin and reductive acetyl-CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of 0.04 wt.% combined with S-34 estimates of up to 18 parts per thousand point to a non-sulphidic depository. Positive Si-30 records of up to +0.53 parts per thousand in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative Si-30 data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Geobiology
volume
13
issue
3
pages
225 - 244
publisher
Wiley-Blackwell
external identifiers
  • wos:000352728600002
  • scopus:84927082882
ISSN
1472-4669
DOI
10.1111/gbi.12128
language
English
LU publication?
yes
id
2b71788c-5609-454f-a365-c67aa410e9a6 (old id 5401286)
date added to LUP
2015-05-19 11:38:09
date last changed
2017-03-19 03:21:45
@article{2b71788c-5609-454f-a365-c67aa410e9a6,
  abstract     = {A 2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a 5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk C-13 isotopic compositions lower than -25 parts per thousand provide evidence for biological contribution by the Calvin and reductive acetyl-CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of 0.04 wt.% combined with S-34 estimates of up to 18 parts per thousand point to a non-sulphidic depository. Positive Si-30 records of up to +0.53 parts per thousand in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative Si-30 data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.},
  author       = {Fru, E. Chi and Ivarsson, M. and Kilias, S. P. and Frings, Patrick and Hemmingsson, C. and Broman, C. and Bengtson, S. and Chatzitheodoridis, E.},
  issn         = {1472-4669},
  language     = {eng},
  number       = {3},
  pages        = {225--244},
  publisher    = {Wiley-Blackwell},
  series       = {Geobiology},
  title        = {Biogenicity of an Early Quaternary iron formation, Milos Island, Greece},
  url          = {http://dx.doi.org/10.1111/gbi.12128},
  volume       = {13},
  year         = {2015},
}