Biosphere expansion drives Earth's secular oxygenation while tectonics modulate oxygen variability revealed by...

Area of Science:

• Geochemistry
• Paleoclimatology
• Earth System Science

Background:

• Atmospheric oxygen's rise transformed Earth and enabled complex life.
• Understanding long-term oxygen fluctuations is limited by proxy resolution and temporal coverage.
• Trace elements in sedimentary pyrite serve as archives for ancient ocean redox conditions and atmospheric oxygen levels.

Purpose of the Study:

• To reconstruct atmospheric oxygen evolution over 3.5 billion years.
• To investigate the relationship between oxygen fluctuations, biosphere expansion, and tectonic events.
• To refine the understanding of Earth's redox evolution and planetary habitability.

Main Methods:

• Integration of high-resolution geochemical data from pyrite grains spanning 3.5 billion years.
• Application of machine learning techniques to analyze trace element data.
• Identification of trace element groups linked to redox-sensitive and hydrothermal influences.

Main Results:

• Reconstruction reveals a tight coupling between the secular trend of atmospheric oxygen and biosphere expansion.
• Short-term oxygen fluctuations are influenced by tectonic events, including supercontinent assembly and breakup.
• Primary oxygenation events correlate with biological expansion; continental assembly is linked to oxygenation, while breakup correlates with reducing conditions.

Conclusions:

• Earth's atmospheric evolution is a complex interplay of biological productivity, tectonics, and ocean chemistry.
• The study refines the temporal dynamics of Earth's redox evolution and provides a framework for understanding early Earth environments.
• Findings inform models of environmental change on early Earth and other potentially habitable planets.