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Paleoenvironmental proxies and what the Xiamaling Formation tells us about the mid-Proterozoic ocean

Zhang, Shuichang ; Wang, Xiaomei ; Wang, Huajian ; Bjerrum, Christian J. ; Hammarlund, Emma U. LU ; Haxen, Emma R. ; Wen, Hanjie ; Ye, Yuntao and Canfield, Donald E. (2019) In Geobiology 17(3). p.225-246
Abstract


The Mesoproterozoic Era (1,600–1,000 million years ago, Ma) geochemical record is sparse, but, nevertheless, critical in untangling relationships between the evolution of eukaryotic ecosystems and the evolution of Earth-surface chemistry. The ca. 1,400 Ma Xiamaling Formation has experienced only very low-grade thermal maturity and has emerged as a promising geochemical archive informing on the interplay between climate, ecosystem organization, and the chemistry of the atmosphere and oceans. Indeed, the geochemical record of portions of the Xiamaling Formation has been used to place minimum constraints on concentrations of atmospheric oxygen as well as possible influences of... (More)


The Mesoproterozoic Era (1,600–1,000 million years ago, Ma) geochemical record is sparse, but, nevertheless, critical in untangling relationships between the evolution of eukaryotic ecosystems and the evolution of Earth-surface chemistry. The ca. 1,400 Ma Xiamaling Formation has experienced only very low-grade thermal maturity and has emerged as a promising geochemical archive informing on the interplay between climate, ecosystem organization, and the chemistry of the atmosphere and oceans. Indeed, the geochemical record of portions of the Xiamaling Formation has been used to place minimum constraints on concentrations of atmospheric oxygen as well as possible influences of climate and climate change on water chemistry and sedimentation dynamics. A recent study has argued, however, that some portions of the Xiamaling Formation deposited in a highly restricted environment with only limited value as a geochemical archive. In this contribution, we fully explore these arguments as well as the underlying assumptions surrounding the use of many proxies used for paleo-environmental reconstructions. In doing so, we pay particular attention to deep-water oxygen-minimum zone environments and show that these generate unique geochemical signals that have been underappreciated. These signals, however, are compatible with the geochemical record of those parts of the Xiamaling Formation interpreted as most restricted. Overall, we conclude that the Xiamaling Formation was most likely open to the global ocean throughout its depositional history. More broadly, we show that proper paleo-environmental reconstructions require an understanding of the biogeochemical signals generated in all relevant modern analogue depositional environments. We also evaluate new data on the δ
98
Mo of Xiamaling Formation shales, revealing possible unknown pathways of molybdenum sequestration into sediments and concluding, finally, that seawater at that time likely had a δ
98
Mo value of about 1.1‰.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
climate, evolution, Mesoproterozoic, molybdenum isotope, oxygen, oxygen minimum zone, proxy
in
Geobiology
volume
17
issue
3
pages
225 - 246
publisher
Wiley-Blackwell
external identifiers
  • pmid:30839152
  • scopus:85062539784
ISSN
1472-4677
DOI
10.1111/gbi.12337
language
English
LU publication?
yes
id
cf9293e1-f327-410f-9fab-db4e78e0cacb
date added to LUP
2019-03-18 15:13:28
date last changed
2020-04-07 05:18:59
@article{cf9293e1-f327-410f-9fab-db4e78e0cacb,
  abstract     = {<p><br>
                                                         The Mesoproterozoic Era (1,600–1,000 million years ago, Ma) geochemical record is sparse, but, nevertheless, critical in untangling relationships between the evolution of eukaryotic ecosystems and the evolution of Earth-surface chemistry. The ca. 1,400 Ma Xiamaling Formation has experienced only very low-grade thermal maturity and has emerged as a promising geochemical archive informing on the interplay between climate, ecosystem organization, and the chemistry of the atmosphere and oceans. Indeed, the geochemical record of portions of the Xiamaling Formation has been used to place minimum constraints on concentrations of atmospheric oxygen as well as possible influences of climate and climate change on water chemistry and sedimentation dynamics. A recent study has argued, however, that some portions of the Xiamaling Formation deposited in a highly restricted environment with only limited value as a geochemical archive. In this contribution, we fully explore these arguments as well as the underlying assumptions surrounding the use of many proxies used for paleo-environmental reconstructions. In doing so, we pay particular attention to deep-water oxygen-minimum zone environments and show that these generate unique geochemical signals that have been underappreciated. These signals, however, are compatible with the geochemical record of those parts of the Xiamaling Formation interpreted as most restricted. Overall, we conclude that the Xiamaling Formation was most likely open to the global ocean throughout its depositional history. More broadly, we show that proper paleo-environmental reconstructions require an understanding of the biogeochemical signals generated in all relevant modern analogue depositional environments. We also evaluate new data on the δ                             <br>
                            <sup>98</sup><br>
                                                         Mo of Xiamaling Formation shales, revealing possible unknown pathways of molybdenum sequestration into sediments and concluding, finally, that seawater at that time likely had a δ                             <br>
                            <sup>98</sup><br>
                                                         Mo value of about 1.1‰.                         <br>
                        </p>},
  author       = {Zhang, Shuichang and Wang, Xiaomei and Wang, Huajian and Bjerrum, Christian J. and Hammarlund, Emma U. and Haxen, Emma R. and Wen, Hanjie and Ye, Yuntao and Canfield, Donald E.},
  issn         = {1472-4677},
  language     = {eng},
  month        = {03},
  number       = {3},
  pages        = {225--246},
  publisher    = {Wiley-Blackwell},
  series       = {Geobiology},
  title        = {Paleoenvironmental proxies and what the Xiamaling Formation tells us about the mid-Proterozoic ocean},
  url          = {http://dx.doi.org/10.1111/gbi.12337},
  doi          = {10.1111/gbi.12337},
  volume       = {17},
  year         = {2019},
}