Thirty years ago, a series of key papers were published on the topic
of deep carbon, tackling the geochemical, petrological and
geophysical consequences of its cycling through the various Earth's
envelops. Over the last 10 years, this topic has regained in
interest, certainly due to the need in better reconstructing
paleo-atmospheric CO2 content, which requires a better definition of
this other -deep- carbon cycle. The aim of this session is to
confront the various methods and various scales assessing the
multiple questions raised by carbon in the Earth's interior. Carbon
emitted in the atmosphere from volcanic and metamorphic areas show
that a few remarkable sites emit enormous quantity of carbon, other
regions being in comparison in a sort of background. The geodynamic
perspective of carbon cycling remains poorly able to explain these
observations and this contradiction might be discussed here.
Discussions on the amount and the modalities of carbon burial and
storage in the deep crust are expected and the introduction of carbon
in subduction zones remains a key aspect on which we would like to
know more. Mantle carbon, its connection to metasomatism and
extrusive rocks such as kimberlites and carbonatites, and the redox
processes relating carbonated to diamondiferous rocks will be
debated. Finally, we anticipate contributions discussing secular
variations in the cycling of carbon from the primordial planetary
steps to the modern and future terrestrial planets.