Pre-biotic carbon dioxide on Earth originated primarily from mantle degassing and volcanic outgassing

The retrieved papers consistently support the standard geochemical model that Earth's early and pre-biotic atmospheric carbon dioxide was primarily sourced from interior degassing (such as mantle and volcanic outgassing). While some recent papers debate the exact redox state and precise composition (e.g., whether H2/CH4 played a larger initial role in certain Hadean niches), papers directly discussing the origin of early carbon dioxide, like the Moon-forming impact aftermath and long-term carbon cycle degassing models, strongly support mantle and volcanic outgassing as the primary sources.