Linking deep CO₂ outgassing to cratonic destruction

Outgassing of carbon dioxide from the Earth's interior regulates the surface climate through deep time. Here we examine the role of cratonic destruction in mantle CO₂ outgassing via collating and presenting new data for Paleozoic kimberlites, Mesozoic basaltic rocks and their mantle xenoliths from the eastern North China Craton (NCC), which underwent extensive destruction in the early Cretaceous. High Ca/Al and low Ti/Eu and δ ²⁶Mg are widely observed in lamprophyres and mantle xenoliths, which demonstrates that the cratonic lithospheric mantle (CLM) was pervasively metasomatized by recycled carbonates. Raman analysis of bubble-bearing melt inclusions shows that redox melting of the C-rich CLM produced carbonated silicate melts with high CO₂ content. The enormous quantities of CO₂ in these magmas, together with substantial CO₂ degassing from the carbonated melt-CLM reaction and crustal heating, indicate that destruction of the eastern NCC resulted in rapid and extensive mantle CO₂ emission, which partly contributed to the early Cretaceous greenhouse climate episode.