1. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007 BREAKOUT SESSION 2: DEEP CARBON FLUXES What are the key unanswered questions?  What are abundances and chemical states with depth of key species in the mantle? Carbon (COx, graphite, recycled from surface, other?), related species (Fe, H, Nb, redox state [fO2], 3He)  What is the nature of the major processes that deliver carbon toward the surface? Under MOR? OI? Arc? Fore-arcs? Back-arcs?  How do vertical fluxes vary over various timescales? Modern fluxes versus longer timescales. Tectonics variations over deep time (spreading rates, geothermal gradient, etc).  MOR: how do C fluxes vary along the ridges (80 to 90 percent of global magma production today)?  OI: Present versus past fluxes (episodicity)? Overall long-term fluxes?  Subduction zones: C budget wrt to re-injection vs loss to surface (effect of C species, carbonitized basalt vs sedimentary C, slab PvsT trajectories [wrt plate age, long-term changes, etc.])  Flux methodology: C/3He C/Nb

2. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007 Where do we want to be in 10 years?  Improved quantitative understanding of modern mantle effluxes in MOR, OI, arcs, continents (magnitudes, geographic variations)  Improved quantitative understanding of modern influxes in arcs, continents (chemical states of C, magnitudes, geographic variations)  Variations of fluxes over time (Holocene)  Relationships between heat flow and C fluxes (modern)  Chemical states of C in upper mantle

3. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007 Where do we want to be in 25 years?  Quantitative understanding of modern effluxes in MOR, OI, arcs, continents (magnitudes, geographic variations)  Improved quantitative understanding of modern influxes in arcs, continents (magnitudes, geographic variations)  Carbon abundances and speciation in igneous oceanic crust  Variations of fluxes over time (up to Ga timescales)  Relationships between heat flow and C fluxes (up to Ga timescales)  Quantify basalt carbonatization of igneous oceanic crust, fate of this C along plate trajectory  Chemical states of C in lower mantle  Comparisons with other planets (e.g., Venus, Mars)  Early atmosphere composition, evolution, losses to space 5

4. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007  Carbon partitioning between mantle and core (experiments at relevant T, P, fO2 and compositions)  Carbon partitioning associated with formation of melts and volatile fluids (MOR, subduction zones)  Nanoscale observations of experimental samples and specific field samples (e.g., melt inclusions, etc.)  Basalt carbonatization  Instruments for remote sensing, deep sea platforms What do we need to do to get there: Experiments and new instrumentation?

5. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007  Existing ODP cores  Drilling programs into igneous crust away from ridges  Subduction zone carbon budget  Serpentinites: measure C contents, heterogeneities  Composition, redox budget and permeability of the underlying oceanic crust along trajectory from MOR to subduction zones  Improved methodology for determining fluxes (remote sensing, deep sea cable networks)  Episodic fluxes (seismicity, ice core records, etc.) What do we need to do to get there: Field observations?

6. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007  High pressure C phases (e.g., deep mantle, core)  Partitioning of carbon and other volatiles between mantle and core  Equations of state for C-O-H in fluids and minerals  Flux proxies (e.g., C/Nb, others): understanding principles, identifying new proxies  Transport models What do we need to do to get there: Theoretical advances?

7. basic research needs workshop for Materials Under Extreme Environments Plenary Closing Session June 13, 2007  Systematic studies identified that will improve estimates of fluxes  Modern geographic variations  Through geologic time BREAKOUT SESSION 2: DEEP CARBON FLUXES CONCLUSIONS