Details
Original language | English |
---|---|
Article number | 105742 |
Journal | Precambrian research |
Volume | 344 |
Publication status | Published - 15 Jul 2020 |
Externally published | Yes |
Abstract
Carbonates and cherts in the 3.35 billion-year-old Strelley Pool Formation (Fm.; Australia) host stromatolites that are among the oldest remnants of life on Earth. However, it is still not entirely clear whether these mineral phases are authigenic precipitates, and whether they represent reliable geochemical archives of early Earth environments. Here we present major/trace-element and Nd-isotope data of stromatolitic carbonates, associated crystal-fan carbonates, and cherts in the Strelley Pool Fm. (i) to assess the reliability of these chemical sediments as geochemical archives of the fluids from which they precipitated, (ii) to date the time of formation of carbonate and silica phases, and (iii) to trace the sources of elements prevailing in microbial habitats 3.35 Ga ago. Stromatolitic carbonates plot together with the stratigraphically underlying Marble Bar cherts on a Sm-Nd regression line yielding 3253 ± 320 Ma. In contrast, associated crystal-fan carbonates together with altered Marble Bar cherts yield 2718 ± 220 Ma, suggesting that their Sm-Nd isotope system was reset after deposition. Both types of carbonates, as well as white cherts, show shale-normalized rare earth element and yttrium patterns (REYSN; with the exception of redox-sensitive Ce and Eu and heavy REYSN to middle REYSN depletion) that are parallel to those of modern seawater, indicating a predominantly seawater-derived origin. Positive EuSN anomalies (2.1–2.4), combined with heterogeneous ɛNd3.35Ga values between −3.2 and +5.8 within individual alternating stromatolite laminae, further support that the dissolved fraction of seawater on the ancient carbonate platform was variably affected by both continental weathering and high-temperature hydrothermal fluids contributing elements of both young mafic or older felsic rocks. In conclusion, trace element and Nd isotope data presented here match well with the depositional environment, as characterized based on lithological, geochemical, and stratigraphic relationships, on an early continent, showing at least episodic emergence above the sea level, supporting microbial life on a shallow marine platform.
Keywords
- Authigenic dolomite, Chert, Early life, Nd isotopes, Pilbara Supergroup, Strelley Pool Formation, Stromatolites, Trace elements
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
Sustainable Development Goals
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In: Precambrian research, Vol. 344, 105742, 15.07.2020.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Carbonates and cherts as archives of seawater chemistry and habitability on a carbonate platform 3.35 Ga ago
T2 - Insights from Sm/Nd dating and trace element analysis from the Strelley Pool Formation, Western Australia
AU - Viehmann, Sebastian
AU - Reitner, Joachim
AU - Tepe, Nathalie
AU - Hohl, Simon V.
AU - Van Kranendonk, Martin
AU - Hofmann, Thilo
AU - Koeberl, Christian
AU - Meister, Patrick
N1 - Funding information: We thankfully acknowledge Monika Horschinegg and Wolfgang Obermaier for their assistance in the laboratory and in operating the TIMS and ICP-OES, respectively. We also would like to thank the Deutsche Forschungsgemeinschaft (DFG) for sponsoring the field workshop 2017 in Australia under the majority program SPP1833 “Building a habitable Earth” and to the organizers of the workshop that led to the cooperation of this project. Sebastian Viehmann received funding for project ELEMIN from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 746033. We thankfully acknowledge Monika Horschinegg and Wolfgang Obermaier for their assistance in the laboratory and in operating the TIMS and ICP-OES, respectively. We also would like to thank the Deutsche Forschungsgemeinschaft (DFG) for sponsoring the field workshop 2017 in Australia under the majority program SPP1833 ?Building a habitable Earth? and to the organizers of the workshop that led to the cooperation of this project. Sebastian Viehmann received funding for project ELEMIN from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 746033. All data related to this article are published as tables in the manuscript or supplemental information. Data tables can also be requested without charge from the corresponding author.
PY - 2020/7/15
Y1 - 2020/7/15
N2 - Carbonates and cherts in the 3.35 billion-year-old Strelley Pool Formation (Fm.; Australia) host stromatolites that are among the oldest remnants of life on Earth. However, it is still not entirely clear whether these mineral phases are authigenic precipitates, and whether they represent reliable geochemical archives of early Earth environments. Here we present major/trace-element and Nd-isotope data of stromatolitic carbonates, associated crystal-fan carbonates, and cherts in the Strelley Pool Fm. (i) to assess the reliability of these chemical sediments as geochemical archives of the fluids from which they precipitated, (ii) to date the time of formation of carbonate and silica phases, and (iii) to trace the sources of elements prevailing in microbial habitats 3.35 Ga ago. Stromatolitic carbonates plot together with the stratigraphically underlying Marble Bar cherts on a Sm-Nd regression line yielding 3253 ± 320 Ma. In contrast, associated crystal-fan carbonates together with altered Marble Bar cherts yield 2718 ± 220 Ma, suggesting that their Sm-Nd isotope system was reset after deposition. Both types of carbonates, as well as white cherts, show shale-normalized rare earth element and yttrium patterns (REYSN; with the exception of redox-sensitive Ce and Eu and heavy REYSN to middle REYSN depletion) that are parallel to those of modern seawater, indicating a predominantly seawater-derived origin. Positive EuSN anomalies (2.1–2.4), combined with heterogeneous ɛNd3.35Ga values between −3.2 and +5.8 within individual alternating stromatolite laminae, further support that the dissolved fraction of seawater on the ancient carbonate platform was variably affected by both continental weathering and high-temperature hydrothermal fluids contributing elements of both young mafic or older felsic rocks. In conclusion, trace element and Nd isotope data presented here match well with the depositional environment, as characterized based on lithological, geochemical, and stratigraphic relationships, on an early continent, showing at least episodic emergence above the sea level, supporting microbial life on a shallow marine platform.
AB - Carbonates and cherts in the 3.35 billion-year-old Strelley Pool Formation (Fm.; Australia) host stromatolites that are among the oldest remnants of life on Earth. However, it is still not entirely clear whether these mineral phases are authigenic precipitates, and whether they represent reliable geochemical archives of early Earth environments. Here we present major/trace-element and Nd-isotope data of stromatolitic carbonates, associated crystal-fan carbonates, and cherts in the Strelley Pool Fm. (i) to assess the reliability of these chemical sediments as geochemical archives of the fluids from which they precipitated, (ii) to date the time of formation of carbonate and silica phases, and (iii) to trace the sources of elements prevailing in microbial habitats 3.35 Ga ago. Stromatolitic carbonates plot together with the stratigraphically underlying Marble Bar cherts on a Sm-Nd regression line yielding 3253 ± 320 Ma. In contrast, associated crystal-fan carbonates together with altered Marble Bar cherts yield 2718 ± 220 Ma, suggesting that their Sm-Nd isotope system was reset after deposition. Both types of carbonates, as well as white cherts, show shale-normalized rare earth element and yttrium patterns (REYSN; with the exception of redox-sensitive Ce and Eu and heavy REYSN to middle REYSN depletion) that are parallel to those of modern seawater, indicating a predominantly seawater-derived origin. Positive EuSN anomalies (2.1–2.4), combined with heterogeneous ɛNd3.35Ga values between −3.2 and +5.8 within individual alternating stromatolite laminae, further support that the dissolved fraction of seawater on the ancient carbonate platform was variably affected by both continental weathering and high-temperature hydrothermal fluids contributing elements of both young mafic or older felsic rocks. In conclusion, trace element and Nd isotope data presented here match well with the depositional environment, as characterized based on lithological, geochemical, and stratigraphic relationships, on an early continent, showing at least episodic emergence above the sea level, supporting microbial life on a shallow marine platform.
KW - Authigenic dolomite
KW - Chert
KW - Early life
KW - Nd isotopes
KW - Pilbara Supergroup
KW - Strelley Pool Formation
KW - Stromatolites
KW - Trace elements
UR - http://www.scopus.com/inward/record.url?scp=85084035533&partnerID=8YFLogxK
U2 - 10.1016/j.precamres.2020.105742
DO - 10.1016/j.precamres.2020.105742
M3 - Article
AN - SCOPUS:85084035533
VL - 344
JO - Precambrian research
JF - Precambrian research
SN - 0301-9268
M1 - 105742
ER -