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Updated: Aug 7, 2026
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Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
The evolution of the Earth's surface iron cycle
Florian Scholz1, Sebastian Doetterl2, Dalton S Hardisty3
1Department of Earth System Sciences, University of Hamburg, Hamburg 20146, Germany.
Summary
Reactive iron (Fe) cycling in marine sediments significantly impacts Earth's atmosphere and oceans. This study reveals that continental weathering, not just redox changes, controls Fe burial, influencing oxygen levels over geological time.
Area of Science:
- Geochemistry
- Paleoceanography
- Earth History
Background:
- Pyrite formation in marine sediments controls atmospheric oxygen and ocean buffering.
- The evolution of reactive iron (Fe) oxide precursors is poorly understood.
- Sedimentary reactive Fe variability is often attributed solely to redox changes.
Purpose of the Study:
- To differentiate redox influences from other controls on sedimentary reactive Fe.
- To investigate the long-term evolution of reactive Fe.
- To understand the interplay between Fe cycling, weathering, and atmospheric oxygen.
Main Methods:
- Developed a novel approach to distinguish redox from other controls on sedimentary reactive Fe.
- Analyzed a 1,200-million-year compilation of sedimentary reactive Fe data.
- Compared Fe data with proxies for continental weathering and land-ocean fluxes.
Main Results:
- Reactive Fe proportions were low from the Mesoproterozoic to Cambrian, rising in the mid- to late Paleozoic, and declining in the late Cenozoic.
- This pattern suggests controls beyond redox, including silicate weathering and erosion.
- The Paleozoic Fe rise correlates with plant proliferation and rising atmospheric oxygen.
Conclusions:
- Sedimentary reactive Fe burial is strongly coupled to oxidative silicate weathering and tectonic erosion.
- Earth-surface Fe cycling is influenced by, and contributes to, atmospheric oxygenation.
- A positive feedback loop exists between Fe cycling and oxygenation, amplified by land plant evolution.
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