Subducted organic matter buffered by marine carbonate rules the carbon isotopic signature of arc emissions

Tumiati, Simone; Recchia, Sandro; Rémusat, Laurent; Tiraboschi, Carla; Sverjensky, Dimitri A.; Manning, Craig E.; Brovarone, Alberto Vitale; Boutier, Antoine; Spanu, D.; Poli, Stefano

doi:10.1038/s41467-022-30421-5

Cited by 23 publications

(8 citation statements)

References 52 publications

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“…Taking into account that the protolith reacting with the metasomatic melt that originated Saidenbach eclogites was probably part of this original crustal package, and that the melt itself now trapped in the garnets originated in the same crustal package, we argue that the CO 2 content measured in rehomogenized melt inclusions share the same origin, i.e., organic. Moreover, this assumption is in agreement with experimental petrology works, suggesting that oxidative dissolution of graphite in oceanic metasediments is the main process controlling the production of CO 2 in the subducted sedimentary slab at depth >120 km (72).…”

Section: Consequences For Carbon and Water Recyclingsupporting

confidence: 89%

The role of continental subduction in mantle metasomatism and carbon recycling revealed by melt inclusions in UHP eclogites

et al. 2023

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Subduction is the main process that recycles surface material into the mantle. Fluids and melts derived by dehydration and partial melting reactions of subducted continental crust, a major reservoir of volatiles (i.e., H 2 O and CO 2 ) and incompatible elements, can substantially metasomatize and refertilize the mantle. Here, we investigate glassy inclusions of silicate melt of continental origin found in Variscan ultrahigh-pressure eclogites to assess the continental crust contribution to mantle metasomatism and the journey of volatiles, carbon in particular, to the deep roots of mountain belts. We argue that the melt preserved in these inclusions is the agent responsible for mantle metasomatism and subsequent ultrapotassic magmatism in the Variscides. We propose that continental subduction can redistribute a substantial volume of carbon in the continental lithosphere, which is subsequently transferred to the continental crust during postcollisional magmatism and stored for a time length longer than that of the modern carbon cycle.

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Section: Consequences For Carbon and Water Recyclingsupporting

confidence: 89%

The role of continental subduction in mantle metasomatism and carbon recycling revealed by melt inclusions in UHP eclogites

et al. 2023

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“…The release of hydrous fluids during prograde subduction has the potential to transport solute species from the slab into the mantle wedge (Frezzotti et al 2011;Ague and Nicolescu 2014;Piccoli et al 2016;Tian et al 2019;Kelemen et al 2022), which ultimately links the deep cycle of both hydrogen and carbon. Disordered organic carbon is continuously leached by these fluids through oxidative dissolution at shallow levels in the subduction zone, whilst highly ordered graphitic material seems to be more stable but dissolves more readily at subarc depth of > 110 km (Plank and Manning 2019;Tumiati et al 2020Tumiati et al , 2022. The release of carbon from subducting slabs also occurs through dissolution of carbonate minerals in aqueous fluids (Facq et al 2014;Farsang et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Early release of H2O during subduction of carbonated ultramafic lithologies

Eberhard

Plümper

Frost

2023

Contrib Mineral Petrol

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To investigate the effect of carbon-bearing phases on the release of fluids in subducted serpentinites, we performed high-pressure multi-anvil experiments on representative ophicarbonate assemblages over a pressure range from 2.5 GPa to 5 GPa and from 450 °C to 900 °C, across the antigorite-out reaction. Parallel experiments were performed on carbonate-free serpentinites. In all experiments, we monitored and/or controlled the oxygen fugacity. The addition of 20 wt. % CaCO3 to a serpentinite assemblage at 2.5 GPa is found to decrease the onset of the serpentine dehydration by over 100 °C, in comparison to carbonate-free assemblages. Similarly, the final disappearance of serpentine is also affected by the presence of CaCO3. For a bulk CaCO3 content of 20 wt. %, this causes a decrease in maximum stability of antigorite by 50 °C. For a bulk CaCO3 content exceeding 25 wt. %, this difference can be as high as 100 °C in warm and 150 °C in cold subduction zones, causing antigorite to be completely dehydrated at 500 °C. This results from the reaction of CaCO3 with serpentine to form clinopyroxene and Mg-rich carbonates. This reaction, however, causes no discernible decrease in the proportion of carbonate, indicating that the amount of released carbon is insignificant. Whilst CaCO3, therefore, influences serpentine stability, there is no significant effect of hydrous phases on the carbonate stability. On the other hand, a MgCO3-bearing system shows no significant effects on the serpentinite stability field. Further experiments and oxygen fugacity calculations indicate that graphite is not stable in typical magnetite-bearing serpentinites. The reduction of carbonates to graphite would require oxygen fugacities that are 1–2 log units below those of magnetite-bearing serpentinites. This confirms earlier studies and indicates that reduction of carbonates can only occur through the infiltration of external H2-rich fluids.

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“…Graphitic carbon and other carbonaceous materials (CM) derived from biogenic organic matter are ubiquitous components of (meta) sedimentary rocks and they are the main carrier of reduced carbon to the mantle through subduction zones (Hayes and Waldbauer, 2006;Plank and Manning, 2019). This flux of subducted organic carbon sequestered from the biosphere (estimated to ~12 Mt yr −1 ; Plank and Manning, 2019) is involved in the production of carbon-bearing fluids, which can metasomatize the mantle wedge and, eventually, escape back to the atmosphere through volcanic arc gaseous emissions, possibly influencing long-term oscillations of Earth's climate (Hayes and Waldbauer, 2006;Mason et al, 2017;Tumiati et al, 2017;Plank and Manning, 2019;Tumiati and Malaspina, 2019;Sheik et al, 2020;Vitale Brovarone et al, 2020;Tumiati et al, 2022). Therefore, assessing how and to which extent organic carbon is recycled into the mantle, requires to first understand the processes that can extract it from subducted CM.…”

Section: Introductionmentioning

confidence: 99%

Experimental dissolution of carbonaceous materials in water at 1 GPa and 550°C: Assessing the role of carbon forms and redox state on COH fluid production and composition during forearc subduction of organic matter

et al. 2023

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Biogenic carbonaceous material (CM) is the main carrier of organic carbon in the subduction zone and contributes to COH fluid production and volcanic arc gaseous emissions. Here we investigated the effect of the structural, textural and chemical heterogeneity of CM on its reactivity and redox dissolution by conducting short-lived (1 h) experiments, where synthetic analogues of CM (ordered graphite, graphite oxide (GO), mesoporous carbon (MC), Vulcan® carbon (VC) and glass-like carbon (GC)), are reacted with water at P = 1 GPa and T = 550°C—conditions typical of a warm forearc subduction—and fO2 buffered from ΔFMQ ≈ +4 to −7. We show that the amount of dissolved CM (CMdissolved) and the proportion of volatile carbon species (Cvolatile) in the fluid is related both to the structure and the peculiar surficial properties of the carbon forms, such as carbon sp2-and sp3-hybridization, amount of oxygen heteroatoms, presence of oxygenated functional groups (OFGs) and of active sites. MC and graphite (C(sp2) > 93 at%, O < 1 at%, OFGs < 2.3 at%, high proportion of active sites) are relatively inert (CMdissolved < .4 mol%) but the former reacts more extensively at extreme redox conditions (producing CO2 + CO and CO2 + CH4 Cvolatile mixtures at ΔFMQ ≈ +4 and −7, respectively), while the latter has a maximum of Cvolatile production (CO2 + CH4) at ΔFMQ ≈0, which is not observed in a 10-day long run; partly-ordered GO (C(sp3) > 98 at%, O ∼31 at%, OFGs ∼41 at%) is the most reactive material at all redox conditions (CMdissolved > 2.6 mol%) and produces CO2 as the dominant Cvolatile species; disordered GC and VC (C(sp3) < 30 at%, O < 8 at%, OFGs < 30 at%) are more reactive at ΔFMQ ≈ +4 (CMdissolved ∼1 mol%) and ΔFMQ ≈ –7 (CMdissolved > 1 mol%), where Cvolatile is dominantly CO2 and CH4, respectively. Besides the significant deviations from thermodynamically predicted graphite-saturated COH fluid composition and speciation, our results suggests that: 1) immature CM (disordered, rich in C(sp3), O, OFGs) is preferentially dissolved under high fluid fluxes and may buffer fluids to rather oxidizing conditions; 2) a descending flux of oxygen (and hydrogen) bond to CM may exist.

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Subducted organic matter buffered by marine carbonate rules the carbon isotopic signature of arc emissions

Cited by 23 publications

References 52 publications

The role of continental subduction in mantle metasomatism and carbon recycling revealed by melt inclusions in UHP eclogites

The role of continental subduction in mantle metasomatism and carbon recycling revealed by melt inclusions in UHP eclogites

Early release of H2O during subduction of carbonated ultramafic lithologies

Experimental dissolution of carbonaceous materials in water at 1 GPa and 550°C: Assessing the role of carbon forms and redox state on COH fluid production and composition during forearc subduction of organic matter

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