Linking deep CO 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 CO 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 Mg 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 CO content. The enormous quantities of CO in these magmas, together with substantial CO degassing from the carbonated melt-CLM reaction and crustal heating, indicate that destruction of the eastern NCC resulted in rapid and extensive mantle CO emission, which partly contributed to the early Cretaceous greenhouse climate episode.