New insights on the Orosirian carbon cycle, early Cyanobacteria, and the assembly of Laurentia from the Paleoproterozoic Belcher Group

Malcolm S.W. Hodgskiss, Olivia M.J. Dagnaud, Jamie L. Frost, Galen P. Halverson, Mark D. Schmitz, Nicholas L. Swanson-Hysell, Erik A. Sperling

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The Orosirian Period (2050–1800 Ma) of the Paleoproterozoic Era represents an interval between the Great Oxidation Event and Lomagundi-Jatuli Excursion, and the apparent environmental stability of the late Paleoproterozoic to mid-Mesoproterozoic (1800–1300 Ma). Here, we present stratigraphic data, carbon isotope chemostratigraphy, element abundances, and U–Pb zircon depositional ages from the Belcher Group in subarctic Canada, providing an unparallelled global reference section for the Orosirian Period. U–Pb dates of 2018.5 ± 1.0 Ma and 2015.4 ± 1.8 Ma for two tuffs in the Kasegalik Formation (lowest Belcher Group) provide the first robust age constraints for Earth's earliest unambiguous cyanobacterial fossil, Eoentophysalis belcherensis. A tuffaceous shale ∼4 km stratigraphically higher, at the contact of the Flaherty and Omarolluk formations (1854.2 ± 1.6 Ma), provides an age for foreland basin development associated with the collision of the Superior and Hearne cratons. Carbonate carbon isotope data show smooth fluctuations ranging from −2.3 to +3.6‰, reaching a maximum near ca. 1.88 Ga. This trend toward heavier carbon isotope values is interpreted as the result of global orogenesis during Nuna assembly that elevated nutrient supply and sedimentation rates, leading to an increase in the proportion of organic carbon burial relative to carbonate carbon burial.

Original languageEnglish (US)
Pages (from-to)141-152
Number of pages12
JournalEarth and Planetary Science Letters
Volume520
DOIs
StatePublished - Aug 15 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 Elsevier B.V.

Keywords

  • Belcher Group
  • carbon cycle
  • Cyanobacteria
  • Nuna
  • Orosirian
  • Paleoproterozoic

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