Early oxygenation of the terrestrial environment during the Mesoproterozoic
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Summary
This summary is machine-generated.Geochemical data reveal significant sulfur isotope fractionation in ancient terrestrial rocks, indicating oxygen-rich conditions during the Mesoproterozoic era. This suggests early evolution of complex sulfur cycling and oxygen-dependent life forms.
Area Of Science
- Geochemistry
- Paleoclimatology
- Biogeochemistry
Background
- Geochemical data from ancient sedimentary rocks track Earth's atmospheric and oceanic evolution.
- Key oxygenation events are proposed for the Palaeoproterozoic and late Proterozoic eras, linked to metazoan evolution.
- Sulfur isotope fractionation (Δ(34)S) data show a shift from <25‰ to ≥50‰ around 1 Gyr ago, interpreted as evolving microbial sulfur cycling.
Observation
- This study reports Mesoproterozoic (1.18 Gyr old) terrestrial sedimentary successions from Scotland with Δ(34)S values exceeding 50‰.
- These high fractionation values were observed in both red beds and lacustrine black shales.
- The Mesoproterozoic period is currently poorly characterized in terms of sulfur cycling and oxygenation.
Findings
- The observed high Δ(34)S values imply sulfur disproportionation, likely involving sulfide-oxidizing bacteria.
- This finding suggests a more complex sulfur cycle than previously inferred from marine records for this time period.
- The data indicate the presence of an oxygenated terrestrial environment supporting adapted biota, including in subsurface sediments.
Implications
- The findings challenge the traditional view of Mesoproterozoic oxygen levels and microbial evolution.
- This suggests that terrestrial environments may have been oxygenated earlier and more widely than previously thought.
- It implies the existence of sophisticated microbial ecosystems capable of significant biogeochemical cycling in the Mesoproterozoic.