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09:45
Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
Pulsed oxidation and biological evolution in the Ediacaran Doushantuo Formation
Kathleen A McFadden1, Jing Huang, Xuelei Chu
1Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Summary
Ocean oxidation during the Ediacaran period depleted dissolved organic carbon (DOC), potentially driving early animal evolution. New data from South China confirm this link, showing oxidation events coupled with eukaryote diversity.
Area of Science:
- Geochemistry
- Paleontology
- Evolutionary Biology
Background:
- Ediacaran ocean oxidation is hypothesized to have driven the evolution of early life.
- This link requires reliable geochemical and paleontological data for validation.
Purpose of the Study:
- To investigate the relationship between ocean oxidation and eukaryote evolution using high-resolution data.
- To analyze geochemical trends in the Doushantuo Formation and compare them with global records.
Main Methods:
- High-resolution geochemical analysis of the Doushantuo Formation (635-551 Ma).
- Measurement of carbon isotope composition of organic carbon (delta(13)C(org)) and carbonate (delta(13)C(carb)).
- Analysis of sulfur isotope composition of carbonate-associated sulfate (delta(34)S(CAS)).
Main Results:
- Stable delta(13)C(org) and variable delta(34)S(CAS) indicate a large, buffered dissolved organic carbon (DOC) reservoir with low sulfate.
- Three negative delta(13)C(carb) excursions suggest pulsed oxidation of the DOC reservoir.
- Oxidation events correlate with eukaryote diversity, indicating spatial heterogeneity in distribution and redox conditions.
Conclusions:
- Ocean oxidation events in the Ediacaran Doushantuo Formation were coupled with eukaryote diversification.
- Early eukaryote distribution was likely influenced by redox conditions.
- Global radiation of oxygen-dependent taxa occurred after pervasive ocean oxidation around 551 Ma.
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