Carbonation by fluid–rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

Piccoli, Francesca; Brovarone, Alberto Vitale; Beyssac, Olivier; Martínez, Isabelle; Ague, Jay J.; Chaduteau, Carine

doi:10.1016/j.epsl.2016.03.045

Cited by 94 publications

(123 citation statements)

References 73 publications

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“…As explained in section 2 on the model setup, choosing the flow direction as a free parameter enables the model to explore the variation of general patterns of within-slab flows predicted by various dynamic models; however, it suffers from losing the details of flow dynamics within the slab. In particular, the strong flow focusing, widely documented in the field (Ague, 2007;Barnicoat and Cartwright, 1995;Breeding et al, 2003;Philippot and Selverstone, 1991;Piccoli et al, 2016;Piccoli et al, 2018), and predicted by dynamic models (Faccenda et al, 2009;Malvoisin et al, 2015;Plümper et al, 2017;Wilson et al, 2014), cannot be simulated in the current model. As demonstrated by Wada et al (2012), heterogeneous hydration associated with local flow focusing can promote H 2 O release and reduce its subduction efficiency.…”

Section: Discussionmentioning

confidence: 92%

“…Besides, viscoelastoplastic models suggest that faults formed during slab bending exert a strong control on the fluid flow directions and overall flow pattern within the slab (Faccenda et al, 2009). Indeed, there is various field evidence attesting to the complexity of fluid flows in subducting slabs (Ague, 2007;Barnicoat and Cartwright, 1995;Breeding et al, 2003Breeding et al, , 2004Galvez et al, 2013;Philippot and Selverstone, 1991;Piccoli et al, 2016;Putlitz et al, 2000). Designating flow direction ( ) as a free model parameter, however, enables 10.1029/2019GC008489 us to approximate the overall trend of fluid flows and explore it by setting to different values.…”

Section: Figurementioning

confidence: 99%

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Devolatilization of Subducting Slabs, Part II: Volatile Fluxes and Storage

Tian

Katz

Jones

et al. 2019

Geochem Geophys Geosyst

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Subduction is a crucial part of the long-term water and carbon cycling between Earth's exosphere and interior. However, there is broad disagreement over how much water and carbon is liberated from subducting slabs to the mantle wedge and transported to island-arc volcanoes. In the Tian et al. (2019) Part I, we parameterize the metamorphic reactions involving H 2 O and CO 2 for representative subducting lithologies. On this basis, a two-dimensional reactive transport model is constructed in this Part II. We assess the various controlling factors of CO 2 and H 2 O release from subducting slabs. Model results show that up-slab fluid flow directions produce a flux peak of CO 2 and H 2 O at subarc depths. Moreover, infiltration of H 2 O-rich fluids sourced from hydrated slab mantle enhances decarbonation or carbonation at lithological interfaces, increases slab surface fluxes, and redistributes CO 2 from basalt and gabbro layers to the overlying sedimentary layer. As a result, removal of the cap sediments (by diapirism or off-scraping) leads to elevated slab surface CO 2 and H 2 O fluxes. The modeled subduction efficiency (the percentage of initially subducted volatiles retained until ∼200 km deep) of H 2 O and CO 2 is increased by open-system effects due to fractionation within the interior of lithological layers.

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Section: Discussionmentioning

confidence: 92%

Section: Figurementioning

confidence: 99%

Devolatilization of Subducting Slabs, Part II: Volatile Fluxes and Storage

Tian

Katz

Jones

et al. 2019

Geochem Geophys Geosyst

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“…Our suggested scenario for the redistribution of carbonate within the Mt. Emilius massif is similar to the HP carbonation process documented for metasomatic marbles in the Ligurian and Corsican Alps (Piccoli et al ., ; Scambelluri et al ., ). At these localities, the C fraction of the metamorphic fluid, released by decarbonation and possibly also carbonate dissolution, was trapped within favourable sites during percolation through heterogeneous lithologies at depth.…”

Section: Discussionmentioning

confidence: 99%

Fluid pathways and high‐P metasomatism in a subducted continental slice (Mt. Emilius klippe, W. Alps)

Angiboust

Yamato

Hertgen

et al. 2017

Journal Metamorphic Geology

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The Mt. Emilius klippe (Western Alps, Italy) corresponds to a segment of the stretched Adriatic continental margin metamorphosed at granulite facies during Permian. This slice was subducted during the early Cenozoic Alpine subduction with the underlying eclogite facies remnants of the Tethyan seafloor (Zermatt‐Saas zone). Near the base of the Mt. Emilius massif, there is a shear zone with eclogite facies hydrofracture systems associated with deformation‐induced re‐equilibration of granulites during high‐P metamorphism. In the basal part of the massif, a pluri‐hectometre domain of sheared mafic boudins is hosted in the granulitic paragneiss. In these mafic boudins, there are garnetites, garnet veins and clinopyroxenites, as well as clinozoisite and calcite veins. These features record multiple events of fracture opening, brecciation, boudinage and parallelization of structures coevally with fluid–rock interaction, metasomatism and volume change. This integrated petrological, micro‐textural and geochemical investigation illustrates the multiplicity and the chemical variability of fluid sources during prograde to peak metamorphic evolution in the lawsonite–eclogite‐facies field (at ~2.15–2.4 GPa, 500–550 °C) during subduction of the Mt. Emilius slice. The calcite veins crosscutting the garnetites have relatively low δ18OVSMOW values (∼+6.5‰) near those for marble layers (and nearby calcsilicates) embedded within the metasomatized granulites (+8 to +10‰). It is proposed that infiltration of externally‐derived H2O‐rich fluids derived from the plate interface flushed the marbles, promoting decarbonation followed by short‐distance transport and re‐precipitation along garnetite fractures. This study highlights the importance of inherited structural heterogeneities (such as mafic bodies or sills) in localizing deformation, draining fluids from the downgoing plate and creating long‐lasting mechanical instabilities during subduction zone deformation.

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“…Exhumed metamorphic terranes provide essential insights into the mechanisms of deep carbon recycling and mobilization in subduction zones (Bebout & Penniston‐Dorland, ; Ferrando, Groppo, Frezzotti, Castelli, & Proyer, ; Piccoli et al., ; Scambelluri et al., ). Thermodynamic calculations and studies of eclogite facies marbles and carbonated eclogites and serpentinites in palaeo‐subducted metamorphic terranes show that carbonate minerals undergo variable extents of decarbonation and can be stable at high pressure (Collins et al., ; Connolly, ; Cook‐Kollars, Bebout, Collins, Angiboust, & Agard, ; Ferrando et al., ; Proyer, Mposkos, Baziotis, & Hoinkes, ).…”

Section: Introductionmentioning

confidence: 99%

Subduction metamorphism of serpentinite‐hosted carbonates beyond antigorite‐serpentinite dehydration (Nevado‐Filábride Complex, Spain)

Menzel

Garrido

Sánchez‐Vizcaíno

et al. 2019

Journal Metamorphic Geology

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At sub‐arc depths, the release of carbon from subducting slab lithologies is mostly controlled by fluid released by devolatilization reactions such as dehydration of antigorite (Atg‐) serpentinite to prograde peridotite. Here we investigate carbonate–silicate rocks hosted in Atg‐serpentinite and prograde chlorite (Chl‐) harzburgite in the Milagrosa and Almirez ultramafic massifs of the palaeo‐subducted Nevado‐Filábride Complex (NFC, Betic Cordillera, S. Spain). These massifs provide a unique opportunity to study the stability of carbonate during subduction metamorphism at P–T conditions before and after the dehydration of Atg‐serpentinite in a warm subduction setting. In the Milagrosa massif, carbonate–silicate rocks occur as lenses of Ti‐clinohumite–diopside–calcite marbles, diopside–dolomite marbles and antigorite–diopside–dolomite rocks hosted in clinopyroxene‐bearing Atg‐serpentinite. In Almirez, carbonate–silicate rocks are hosted in Chl‐harzburgite and show a high‐grade assemblage composed of olivine, Ti‐clinohumite, diopside, chlorite, dolomite, calcite, Cr‐bearing magnetite, pentlandite and rare aragonite inclusions. These NFC carbonate–silicate rocks have variable CaO and CO2 contents at nearly constant Mg/Si ratio and high Ni and Cr contents, indicating that their protoliths were variable mixtures of serpentine and Ca‐carbonate (i.e., ophicarbonates). Thermodynamic modelling shows that the carbonate–silicate rocks attained peak metamorphic conditions similar to those of their host serpentinite (Milagrosa massif; 550–600°C and 1.0–1.4 GPa) and Chl‐harzburgite (Almirez massif; 1.7–1.9 GPa and 680°C). Microstructures, mineral chemistry and phase relations indicate that the hybrid carbonate–silicate bulk rock compositions formed before prograde metamorphism, likely during seawater hydrothermal alteration, and subsequently underwent subduction metamorphism. In the CaO–MgO–SiO2 ternary, these processes resulted in a compositional variability of NFC serpentinite‐hosted carbonate–silicate rocks along the serpentine‐calcite mixing trend, similar to that observed in serpentinite‐hosted carbonate‐rocks in other palaeo‐subducted metamorphic terranes. Thermodynamic modelling using classical models of binary H2O–CO2 fluids shows that the compositional variability along this binary determines the temperature of the main devolatilization reactions, the fluid composition and the mineral assemblages of reaction products during prograde subduction metamorphism. Thermodynamic modelling considering electrolytic fluids reveals that H2O and molecular CO2 are the main fluid species and charged carbon‐bearing species occur only in minor amounts in equilibrium with carbonate–silicate rocks in warm subduction settings. Consequently, accounting for electrolytic fluids at these conditions slightly increases the solubility of carbon in the fluids compared with predictions by classical binary H2O–CO2 fluids, but does not affect the topology of phase relations in serpentinite‐hosted carbonate‐rocks. Phase relations, mineral c...

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Carbonation by fluid–rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

Cited by 94 publications

References 73 publications

Devolatilization of Subducting Slabs, Part II: Volatile Fluxes and Storage

Devolatilization of Subducting Slabs, Part II: Volatile Fluxes and Storage

Fluid pathways and high‐P metasomatism in a subducted continental slice (Mt. Emilius klippe, W. Alps)

Subduction metamorphism of serpentinite‐hosted carbonates beyond antigorite‐serpentinite dehydration (Nevado‐Filábride Complex, Spain)

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