Isotope fractionation and atmospheric oxygen: implications for phanerozoic O(2) evolution

Area of Science:

• Geochemistry
• Paleoclimatology
• Paleontology

Background:

• Models of atmospheric oxygen (O2) evolution are limited by ocean carbon and sulfur mass balance.
• Previous models restricted the exploration of negative feedback mechanisms for O2 regulation.
• Maintaining biologically permissible O2 levels has been a key challenge in Earth system science.

Purpose of the Study:

• To develop a novel modeling approach for Phanerozoic O2 history.
• To incorporate O2-dependent carbon and sulfur isotope fractionation into models.
• To test hypotheses regarding atmospheric O2 levels during the Carboniferous.

Main Methods:

• Utilized laboratory experimental data on carbon-13 discrimination in plants and plankton.
• Integrated O2-dependent isotope fractionation into mass balance models.
• Calculated Phanerozoic atmospheric O2 concentrations.

Main Results:

• The new model aligns with existing independent models of O2 evolution.
• Results are consistent with biological and physical constraints on atmospheric O2.
• The model supports a high O2 concentration during the Carboniferous.

Conclusions:

• The developed modeling approach provides a robust method for reconstructing past atmospheric O2.
• High Carboniferous O2 levels may have facilitated the evolution of gigantism in terrestrial arthropods.
• This study refines our understanding of long-term atmospheric O2 dynamics and its biological implications.