Linking deep CO2 outgassing to cratonic destruction

Abstract

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 δ26Mg 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 contents. The enormous quantities of CO2 in these magmas, together with subtantial CO2 degassing from 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.

Tracing deep carbon cycling by metal stable isotopes

“…A Research Article by Wang et al. argues that the destruction of the eastern North China craton was responsible for rapid and massive CO 2 outgassing into the early Cretaceous atmosphere, hence inducing climate change at that time [ 2 ]. This new idea is highlighted by Graham Pearson from the University of Alberta [ 3 ].…”

A link between the destruction of the mantle root beneath the North China Craton and the Cretaceous Greenhouse

“…In a novel study, Wang et al . [ 5 ] assemble a compelling and diverse array of evidence for the major release of CO 2 during the destruction of much of the lithosphere beneath the NCC. First, they establish that the ancient, thick, pre-Cretaceous lithosphere beneath the eastern portion of the NCC must have contained a significant amount of carbon, from eons of metasomatic enrichment, culminating in the multiple subduction episodes witnessed by this craton in the Phanerozoic.…”

“…Through spectroscopic analysis of gas bubbles within tiny melt inclusions in NCC lamprophyres, Wang et al . [ 5 ] show that these rocks contained up to 2 wt% CO 2 . Typical basalts have only a few hundred ppm CO 2 .…”

“…Wang et al . [ 5 ] show that the timing of the eruption of these magmas along with associated crustal heating would have resulted in enormous volumes of CO 2 released into the early Cretaceous atmosphere, likely accentuating the ‘Cretaceous Greenhouse’ episode.…”

“…This remarkable result [ 5 ] leads to obvious interest in whether the lithospheric root destruction events associated with numerous other modified cratons, for example those shown in ref. [ 2 ], may have also made contributions to ancient spikes in atmospheric CO 2 , and whether these events might be detected in the geological and geochemical records that we are increasingly able to read at high fidelity.…”