What introduced oxygen and ended abiotic chemical evolution?

The introduction of oxygen into Earth's atmosphere and the cessation of abiotic chemical evolution are primarily attributed to the process of photosynthesis. This is primarily carried out by photosynthetic organisms, such as cyanobacteria, which convert carbon dioxide and water into glucose and oxygen using sunlight. This oxygen production gradually enriched the atmosphere with oxygen, leading to significant changes in the environment and paving the way for aerobic life forms.

While autotrophs, which include photosynthetic organisms, do play a critical role in producing organic compounds and oxygen, the specific process that directly introduced oxygen and ended abiotic chemical evolution is photosynthesis. Autotrophs as a broad category can include organisms that use various methods of synthesis (like chemosynthesis), but it was photosynthetic autotrophs specifically that released oxygen into the atmosphere.

The emergence of heterotrophs came later, as they depend on organic material produced by autotrophs. Thermal vents were important for early life forms but do not significantly relate to the introduction of atmospheric oxygen. Thus, the process of photosynthesis is the key event that marked the transition from a reducing atmosphere, devoid of free oxygen, to one that supports complex aerobic life.