Unravelling the extent of ocean euxinia during the late Paleoproterozoic: Constraints from Re–Os and Mo isotopes
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F25%3A00638883" target="_blank" >RIV/67985831:_____/25:00638883 - isvavai.cz</a>
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S0016703725004806?dgcid=coauthor" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0016703725004806?dgcid=coauthor</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.gca.2025.09.013" target="_blank" >10.1016/j.gca.2025.09.013</a>
Alternative languages
Result language
angličtina
Original language name
Unravelling the extent of ocean euxinia during the late Paleoproterozoic: Constraints from Re–Os and Mo isotopes
Original language description
Oceanic euxinia was one of the prime constraints for the Proterozoic nutrient availability and hence, eukaryotic expansion. Although available studies mostly point to the occurrence of sulfidic to ferruginous conditions in the Paleoproterozoic ocean, data on the areal extent of sulfidic settings are scarce. In this study, geochemical (major and trace elements, and iron-speciation), and Re–Os and Mo isotopic data for black shales from the Cumbum Formation, Cuddapah Basin (India) are presented. These datasets are used to constrain the depositional age and environment, and euxinic extent for the late Paleoproterozoic ocean. The Re–Os isochron for these shales provides a depositional (Model 3) age of 1658 ± 50 Ma (2σ, n = 10), with an initial 187Os/188Os (Os.sub/sub.) ratio of 0.03 ± 0.53. Distribution of enrichment factors (EF) for redox-sensitive elements and their (MoEF/UEF) ratio for the Cumbum shales indicates shale deposition in an anoxic basin. Further, high FeHR/FeT (0.61 ± 0.18 (1σ)) and FePy/FeHR (0.72 ± 0.14 (1σ)) ratios confirm euxinic to ferruginous bottom-water conditions. The δ98Mo values of these shales (+0.68 ± 0.13 ‰ (1σ)) are comparable to Paleoproterozoic shales (+0.51 ± 0.57 ‰ (1σ)) and systematically lower in comparison to the present-day average seawater (+2.34 ± 0.10 ‰ (1σ)) and euxinic sediments (+1.8 ± 0.4 ‰ (1σ)) values. A mass balance modelling using Mo isotopic values of euxinic shales, their major sources and sinks, and related fractionation factors suggests an order of magnitude higher extent of ocean euxinia (∼5% of seafloor area) at 1.66 Ga than that observed for modern oceans (0.1 to 0.3 %). Such extensive euxinia in shallow-water environments under a weakly oxygenated atmosphere (≥0.1 % PAL to ≤40 % PAL) could have played a major role in delaying the emergence of eukaryotes and multicellular life.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10505 - Geology
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Geochimica et Cosmochimica Acta
ISSN
0016-7037
e-ISSN
1872-9533
Volume of the periodical
407
Issue of the periodical within the volume
October
Country of publishing house
GB - UNITED KINGDOM
Number of pages
16
Pages from-to
158-173
UT code for WoS article
001584061800003
EID of the result in the Scopus database
2-s2.0-105015422715