Chromium evidence for protracted oxygenation during the Paleoproterozoic

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: This is version 2 of this Preprint.

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Kaarel Mänd , Noah J. Planavsky , Susannah M Porter, Changle Wang, Timmu Kreitsmann , Kärt Paiste , Päärn Paiste, Alexander E. Romashkin, Yulia E. Deines , Kalle Kirsimäe , Aivo Lepland, Kurt O. Konhauser , Leslie J. Robbins


It has commonly been proposed that the development of complex life—e.g., aerobic eukaryotes—coincided with atmospheric oxygenation. To test this hypothesis, we measured chromium-based oxygen proxies in a >2400-m core from the Onega Basin (NW-Russia), deposited ~2.1–2.0 billion years ago—closely preceding the first eukaryote fossils. Fractionated chromium isotopes are documented throughout the section (max. 1.63±0.10‰ δ53Cr), suggesting higher and more stable oxygen levels during this interval (possibly >100 million years) than persisted for much of the billion years before or after. Significantly, unambiguous eukaryotic fossils have not been found in the Onega Basin or any contemporaneous successions. While this does not discount an increase in biological complexity during this oxic interval, our study calls into question the causative correlation between oxygenation and biological innovation. This work further highlights that while oxygenation is a necessary precursor for diverse eukaryote rich ecosystems, it need not drive eukaryogenesis or diversification.



Earth Sciences, Geochemistry, Paleobiology


Eukaryogenesis, paleoredox


Published: 2021-05-18 03:03


CC BY Attribution 4.0 International

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Conflict of interest statement:

Data Availability (Reason not available):
Data will be published on the Pangaea data repository once peer review has progressed further; currently the data was provided to reviewers as xlsx files for ease of reviewing.