Fig. 4: Redox state of mantle-derived melts controlled by the thermal state of the mantle.
From: The constant oxidation state of Earth’s mantle since the Hadean
Cartoon illustrating the higher TP in Archean caused deeper and more extensive melting of the mantle, resulting in lower fo2 of Archean magmas (a). In contrast, the lower TP during the Phanerozoic led to shallower melts with higher oxidation due to the mantle’s redox structure20,31 (b). The concurrent cooling and oxidation of mantle-derived melts at the end of the Archean played a crucial role in transforming volcanic gases from an anoxic to an oxic state, potentially triggering atmospheric oxygenation. The stagnant-lid tectonic regime in Archean was from ref. 65.
