TY - JOUR
T1 - Biological Soil Crusts as Modern Analogs for the Archean Continental Biosphere
T2 - Insights from Carbon and Nitrogen Isotopes
AU - Thomazo, Christophe
AU - Couradeau, Estelle
AU - Giraldo-Silva, Anna
AU - Marin-Carbonne, Johanna
AU - Brayard, Arnaud
AU - Homann, Martin
AU - Sansjofre, Pierre
AU - Lalonde, Stefan V.
AU - Garcia-Pichel, Ferran
N1 - Publisher Copyright:
© Copyright 2020, Mary Ann Liebert, Inc., publishers 2020.
PY - 2020/7/1
Y1 - 2020/7/1
N2 - Stable isotope signatures of elements related to life such as carbon and nitrogen can be powerful biomarkers that provide key information on the biological origin of organic remains and their paleoenvironments. Marked advances have been achieved in the last decade in our understanding of the coupled evolution of biological carbon and nitrogen cycling and the chemical evolution of the early Earth thanks, in part, to isotopic signatures preserved in fossilized microbial mats and organic matter of marine origin. However, the geologic record of the early continental biosphere, as well as its evolution and biosignatures, is still poorly constrained. Following a recent report of direct fossil evidence of life on land at 3.22 Ga, we compare here the carbon and nitrogen isotopic signals of this continental Archean biosphere with biosignatures of cyanobacteria biological soil crusts (cyanoBSCs) colonizing modern arid environments. We report the first extended δ13C and δ15N data set from modern cyanoBSCs and show that these modern communities harbor specific isotopic biosignatures that compare well with continental Archean organic remains. We therefore suggest that cyanoBSCs are likely relevant analogs for the earliest continental ecosystems. As such, they can provide key information on the timing, extent, and possibly mechanism of colonization of the early Earth's emergent landmasses.
AB - Stable isotope signatures of elements related to life such as carbon and nitrogen can be powerful biomarkers that provide key information on the biological origin of organic remains and their paleoenvironments. Marked advances have been achieved in the last decade in our understanding of the coupled evolution of biological carbon and nitrogen cycling and the chemical evolution of the early Earth thanks, in part, to isotopic signatures preserved in fossilized microbial mats and organic matter of marine origin. However, the geologic record of the early continental biosphere, as well as its evolution and biosignatures, is still poorly constrained. Following a recent report of direct fossil evidence of life on land at 3.22 Ga, we compare here the carbon and nitrogen isotopic signals of this continental Archean biosphere with biosignatures of cyanobacteria biological soil crusts (cyanoBSCs) colonizing modern arid environments. We report the first extended δ13C and δ15N data set from modern cyanoBSCs and show that these modern communities harbor specific isotopic biosignatures that compare well with continental Archean organic remains. We therefore suggest that cyanoBSCs are likely relevant analogs for the earliest continental ecosystems. As such, they can provide key information on the timing, extent, and possibly mechanism of colonization of the early Earth's emergent landmasses.
KW - Archean
KW - Carbon isotope
KW - Early life
KW - Isotope biosignature
KW - Nitrogen isotope. Astrobiology 20, 815-819
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U2 - 10.1089/ast.2019.2144
DO - 10.1089/ast.2019.2144
M3 - Article
C2 - 32293913
AN - SCOPUS:85088204857
SN - 1531-1074
VL - 20
SP - 815
EP - 819
JO - Astrobiology
JF - Astrobiology
IS - 7
ER -