The standard story
For most of the 20th century, the Earth-system science consensus on oxygen looked like this:
- Around 2.45 billion years ago, oxygen-producing bacteria had been at it long enough that atmospheric oxygen finally rose above trace levels for the first time. This is called the
Great Oxidation Event (GOE).
- Around 2.22 to 2.06 billion years ago, oxygen briefly spiked. This is the
Lomagundi-Jatuli excursion.
- After the Lomagundi pulse ended, the planet went through a long stretch of low-oxygen, low-nutrient conditions called the
Boring Billion (1.8 to 0.8 billion years ago), during which complex life either could not evolve or evolved extremely slowly.
- Things finally got interesting again with the Neoproterozoic oxygenation around 800 million years ago, leading to the Cambrian explosion of animal life 540 million years ago.
The key claim of the standard story is that the post-Lomagundi crash was sharp and severe. The atmosphere went anoxic again, the oceans went anoxic again, and complex life had to wait.
The 2020 paper that broke the story
In 2020, a team led by
Kaarel Mänd at the University of Alberta, working with collaborators from the Karelian Research Centre in Petrozavodsk, the Geological Survey of Norway, and other institutions, published "
Palaeoproterozoic oxygenated oceans following the Lomagundi-Jatuli Event" in
Nature Geoscience.
They had analysed shungite from the Karelian Zaonega Formation. They were looking at trace metal concentrations:
molybdenum, uranium, rhenium. These three elements share a useful property. They are mobile in oxygen-rich water (they dissolve, they get carried by ocean currents) and immobile in oxygen-poor water (they precipitate out). When you find them concentrated in an organic-rich sediment from a particular geological age, it is direct evidence that the water above that sediment was oxygenated when the sediment formed.
The Mänd team measured
strikingly high concentrations. Their phrasing in the paper itself is that the levels were "
unrivaled in early Earth's history". The Karelian shungite was depositing in seawater that contained more dissolved oxygen-mobile metals than at almost any other point in the planet's pre-Phanerozoic record.
What this means
The shungite carbon was deposited around 2.0 billion years ago, on the falling tail of the Lomagundi excursion. Under the standard story, oxygen should have already started crashing by then.
The shungite trace-metal record says it didn't. Or at least, not where shungite was forming. The seas above the Karelian basin were still oxygen-rich, well after the Lomagundi pulse was supposed to be over.
The team's interpretation:
high atmospheric and oceanic oxygen levels persisted significantly longer than the textbook timeline suggests. The post-Lomagundi crash, if it happened at all, was not a clean global event. The Earth's oxygen story had a long tail of oxygenated conditions extending well past where geochemists had previously placed the crash.
The implication for biology is direct. The lead author was quoted in the paper's press coverage:
"This work now strengthens the suggestion that suitable conditions for the evolution of complex life on early Earth existed for a much longer time than previously thought."
If oxygen-rich conditions persisted longer, then the evolutionary window for complex life (eukaryotic cells, multicellularity, the precursors of everything that makes you possible) was longer too. The Boring Billion may have been less boring than its name suggests, at least at the front end. The Karelian shungite is the rock that most directly demonstrates this.
Why shungite specifically
The thing that makes shungite valuable as an oxygen-history witness is two-fold.
First, it is enormous. The Karelian deposit covers around 9,000 square kilometres and contains an estimated 25 × 10^10 tonnes of organic carbon (Melezhik, Filippov, Romashkin 2004,
Ore Geology Reviews). When you have that much organic-rich rock concentrated in one place, you have a high-resolution time series. You can sample at many points and reconstruct what was happening to the chemistry of the seas above the basin over a long stretch of geological time.
Second, the carbon in shungite is biogenic. Qu, Črne, Lepland, Van Zuilen 2012 (
Geobiology 10:467) confirmed that the carbon source was bacterial methanotrophs living on the basin floor. That biogenic origin is what binds the trace-metal record to the chemistry of the water column. The bacteria scavenged trace metals from the seawater they lived in. When their bodies became sediment and then rock, the metals locked into the carbon matrix. Two billion years later, you can extract the metals from the rock and read backwards into the conditions of the water.
This is why the Mänd team wanted Karelian shungite specifically. There is no other rock on Earth that combines the same scale (9,000 km²), the same time window (right at the falling edge of the Lomagundi excursion), and the same biogenic carbon origin (preserving the chemistry of the water it was deposited under).
The further line of work
The Mänd 2020 paper is not isolated. The line of geochemical work using Karelian shungite as a Lomagundi-Event proxy continues:
-
Asael, Tissot, Reinhard et al. 2013 (
Chemical Geology 362:193-210), Mo-Fe-U stable isotope work on the Shunga Event sediments, establishing the multi-element redox proxy framework.
-
Lepland, Joosu, Kirsimäe, Prave, Romashkin et al. 2014 (
Nature Geoscience 7:20), sulfur-bacteria phosphogenesis, the earliest phosphorites coeval with shungite.
-
Paiste, Lepland et al. 2020 (
EPSL 534), pyrite multi-sulfur isotope record of the 1.98 Ga Zaonega Formation.
-
A 2023 paper in Earth-Science Reviews revisited "
Earth's surface oxygenation and the rise of eukaryotic life: relationships to the Lomagundi positive carbon isotope excursion" using updated data including the Karelian samples.
-
A 2025 paper in Nature Communications Earth & Environment on aerobic iron biogeochemistry during the Lomagundi event.
There is, in 2026, a continuous line of peer-reviewed Earth-system science using the Karelian shungite belt as a primary archive of Earth's first oxygen pulse. The rock that shows up in folk tradition as the
aspid stone is, in modern Earth science, one of the most important physical archives of the planet's atmospheric history we have access to.
Where the trail leads
For the Lomagundi-Event-and-shungite literature, the entry points are the FAR-DEEP project (Fennoscandia Arctic Russia Drilling Project), an International Continental Scientific Drilling Program operation that drilled the Karelian craton in the late 2000s. The synthesis volume is Melezhik et al. (eds.)
Reading the Archive of Earth's Oxygenation (3 volumes, Springer Frontiers in Earth Sciences, 2013). The Shunga Event chapter in volume 3 is the deep source for everything in this thread.
For the modern continuing work, follow Kaarel Mänd's publications, the Karelian Research Centre Institute of Geology, and the University of Alberta geochemistry group. The line is active, the questions are open, and shungite is in the middle of them.
Sources
- Mänd K, Lalonde SV, Robbins LJ, Thoby M, Paiste K, Kreitsmann T, Paiste P, Reinhard CT, Romashkin AE, Planavsky NJ, Kirsimäe K, Lepland A, Konhauser KO 2020, "Palaeoproterozoic oxygenated oceans following the Lomagundi-Jatuli Event", Nature Geoscience 13:302-306, DOI 10.1038/s41561-020-0558-5
- Phys.org press coverage 2020-03:
phys.org
- Asael D, Tissot FLH, Reinhard CT, Rouxel O, Dauphas N, Lyons TW, Ponzevera E, Liorzou C, Chéron S 2013, "Coupled molybdenum, iron and uranium stable isotopes as oceanic paleoredox proxies during the Paleoproterozoic Shunga Event", Chemical Geology 362:193-210, DOI 10.1016/j.chemgeo.2013.08.003
- Lepland A, Joosu L, Kirsimäe K, Prave AR, Romashkin AE, Črne AE, Martin AP, Fallick AE, Somelar P, Üpraus K, Mänd K, Roberts NMW, van Zuilen MA, Wirth R, Schreiber A 2014, "Potential influence of sulphur bacteria on Palaeoproterozoic phosphogenesis", Nature Geoscience 7:20-24, DOI 10.1038/ngeo2005
- Paiste K, Lepland A et al. 2020, "The pyrite multiple sulfur isotope record of the 1.98 Ga Zaonega Formation", Earth Planet. Sci. Lett. 534, DOI 10.1016/j.epsl.2020.116092
- Melezhik VA et al. (eds.) 2013,
Reading the Archive of Earth's Oxygenation, 3 volumes, Springer Frontiers in Earth Sciences
- "Expansion of the aerobic iron biogeochemical cycle during the Paleoproterozoic Lomagundi event", Nature Communications Earth & Environment 2025, DOI 10.1038/s43247-025-02106-6
- Qu Y, Črne AE, Lepland A, Van Zuilen MA 2012, "Methanotrophy in a Paleoproterozoic oil field ecosystem, Zaonega Formation, Karelia, Russia", Geobiology 10(6):467-478, DOI 10.1111/gbi.12007
Edited 2026-05-03, source audit. Cited sources verified to exist; no fabricated sources detected. Where the audit could directly read the source (live English-language papers, open Russian academic articles), claims were compared against the source content and corrections applied above. Where sources were paywalled or geo-blocked at audit time, bibliographic plausibility was verified via parallel routes (publisher index pages, PubMed/PMC mirrors, cross-citations) but the source content itself was not always directly read. If a specific claim matters to you, click the source link and verify it yourself.
