On June 15 and 16, 2011, over 80 delegates from the largest French universities (Grenoble, Lyon, Montpellier, Nancy, Nantes, Orléans, Paris, Strasbourg & Toulouse) met at the Institut de Physique du Globe de Paris (IPG-Paris) for a workshop on the Deep Carbon Observatory (DCO). The workshop was organized by Pierre Cartigny (IPG-Paris) and James Badro (IMPMC) under the guidance of Claude Jaupart (IPG-Paris and DCO Executive Committee member). Bob Hazen (Geophysical Laboratory, Carnegie Institution of Washington and DCO Principal Investigator) and French scientists (M. Ader, P. Allard, J. Badro, I. Daniel, B. Marty, M. Pichavant) active within the DCO’s four directorates were also present.
The purpose of the workshop was twofold: (1) to inform French colleagues about the existence, structure and organization of the DCO; and (2) to encourage the French scientific community to meet and work in a more integrated manner to tackle the scientific questions central to the DCO’s efforts.
The meeting’s first morning was devoted to understanding the DCO structure and organization. After Claude Jaupart opened the workshop, Bob Hazen presented the goals of the DCO initiative, its main scientific questions, its structure and how the scientific community can become involved. The morning session ended with a News and Views section, with a representative member giving an update on the lastest information, including future concept papers and proposal deadlines, for each DCO directorate.
Fifteen scientific presentations on June 15th focused on the deepest carbon, i.e., in the mantle and in the core. Several presentations were devoted to estimating carbon fluxes degassed from the mantle which relate to the still debated carbon content of the mantle. Different methods were emphasized, including new ones such as using electrical conductivity to determine carbon distribution at depth. The underestimated role of carbon (either from the mantle or resulting from the assimilation of sediments) in driving volcanic eruptions was emphasized from both the perspectives of geochemistry and experimental petrology. There is significant progress that can be made in this field in the near future.
Heterogeneities in mantle carbon content and isotope composition were highlighted with an emphasis, to interpret these, on our restricted knowledge on both the behaivor of carbonate liquids at depths, and of carbon isotope fractionation factors at high pressure and temperature. The day ended with a series of presentations on the carbon content in the core and how combined experimental and ab-inito studies can bring further insights on this debated matter.
Presentations on June 16th focused on shallower carbon within the continental and oceanic crust. Ten presentations illustrated a wide range of investigations and advances particularly made through the ongoing studies of CO2-sequestration. These include the study of kinetic carbonation reactions either abiotic or biotically-mediated, and satellite-based methods to monitor CO2 fluxes from space.
These approaches all have bearing on the study of the altered oceanic crust which remains one of the least constrained reservoirs on Earth. In particular, methods under discussion could be applied to the study of samples recovered during the Mohole deep drilling project. Finally, the neglected role of mantle and metamorphic CO2-degassing in convergent areas was emphasized and it was proposed that it could be quantified from the geochemistry of rivers.
The afternoon was devoted to open discussions with the objective of having the scientific community working in a more integrated manner to address scientific questions of importance to the DCO now and in the future. Above all, IPGP hopes to build a group of advocates to request a dedicated funding initiative at the Agence Nationale de la Recherche (the French NSF).
Report courtesy of Pierre Cartigny (IPG-Paris)