Quantification of the CO 2 budget and H 2 O–CO 2 systematics in subduction-zone magmas through the experimental hydration of melt inclusions in olivine at high H 2 O pressure

Mironov, Nikita; Portnyagin, Maxim; Botcharnikov, Roman E.; Gurenko, Andrey A.; Hoernle, Kaj; Holtz, François

doi:10.1016/j.epsl.2015.05.043

Cited by 89 publications

(86 citation statements)

References 50 publications

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“…Unfortunately, the literature is replete with measurements of CO 2 in melt inclusions compromised by degassing or bubble formation. After bubble reconstruction, arc melt inclusions may contain thousands of parts per million of CO 2 82,83 , but there is no guarantee that these melts did not lose CO 2 by degassing before inclusion formation. Thus, a major outstanding challenge is to determine the CO 2 concentration of primary arc magmas (Box 4).…”

Section: Carbon Returned: Volcanic Gasmentioning

confidence: 99%

Subducting carbon

Plank

Manning

2019

Nature

358

220

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A hidden carbon cycle exists inside Earth. Every year, megatons of carbon disappear into subduction zones, affecting atmospheric carbon dioxide and oxygen over Earth's history. Here we discuss the processes that move carbon towards subduction zones and transform it into fluids, magmas, volcanic gases and diamonds. The carbon dioxide emitted from arc volcanoes is largely recycled from subducted microfossils, organic remains and carbonate precipitates. The type of carbon input and the efficiency with which carbon is remobilized in the subduction zone vary greatly around the globe, with every convergent margin providing a natural laboratory for tracing subducting carbon.

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Section: Carbon Returned: Volcanic Gasmentioning

confidence: 99%

Subducting carbon

Plank

Manning

2019

Nature

358

220

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“…Quantification of outputs continues to evolve because of the difficulty in measuring CO 2 outgassing. Early estimates indicated that up to 97% of the CO 2 in arc volcanic rocks was derived from the subducting oceanic slab [Hilton et al, 2002], while more recently high pressure experiments have favored~80% as being more typical [Mironov et al, 2015], consistent values derived from measuring CO 2 and 3 He ratios in magmatic volatiles [Marty and Tolstikhin, 1998].…”

Section: Introductionmentioning

confidence: 98%

A revised budget for Cenozoic sedimentary carbon subduction

Clift

2017

Reviews of Geophysics

111

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Carbon plays a pivotal role in governing the climate and biosphere of Earth, yet quantification of carbon's long‐term cycling from the mantle to the surface remains contentious. Sedimentary carbon represents a significant part of the budget and can be recycled to the mantle if underthrust in subduction zones. I estimate that ~60 megaton per year (Mt/yr) is presently being subducted below the outer fore arc, 80% in the form of carbonate carbon, significantly more than previously estimated. Sedimentary carbon represents around two thirds of the total carbon input at the trenches. An additional 7 Mt/yr is averaged over the Cenozoic as a result of passive margin subduction during continental collision (~83% CaCO3). This revision brings the input and output budgets within the range of uncertainty. Degassing from arc volcanoes and fore arcs totals ~55 Mt/yr. When carbon in hydrothermal veins in the altered oceanic crust and serpentinized upper mantle is accounted for, a net flux to the mantle appears likely. The efficiency of carbon subduction is largely controlled by the carbonate contents of the sediment column and is partly linked to the latitude of the trench. Accretionary margins are the biggest suppliers of carbon to the mantle wedge, especially Java, Sumatra, Andaman‐Burma, and Makran, reflecting the inefficiency of offscraping, the thickness of the subducting sediment, and the trench length. The western Pacific trenches are negligible sinks of sedimentary carbon. Increases in deep‐sea carbonate in the Oligocene and middle Mesozoic had a large impact on the subduction budget, increasing it greatly compared to earlier times.

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“…Another approach involved experimental heating of olivine-hosted inclusions, with the aim of rehomogenizing the inclusion system to a silicate melt which can then be quenched to recover the CO 2 content at the time of entrapment [Cervantes and Wallace, 2003;Wallace et al, 2015;Hudgins et al, 2015]. However, it is known that the temperature of homogenization in such experiments is significantly higher than the likely entrapment temperature, a mismatch which will cause the reconstructed relationship between CO 2 and major elements contents of the inclusion system to deviate from the natural case [Sobolev and Danyushevsky, 1994;Massare et al, 2002;Wallace et al, 2015;Mironov et al, 2015;Schiavi et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

Bubble formation and decrepitation control theCO₂content of olivine‐hosted melt inclusions

Maclennan

2017

Geochem Geophys Geosyst

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The CO 2 contents of olivine-hosted melt inclusions have previously been used to constrain the depth of magma chambers in basaltic systems. However, the vast majority of inclusions have CO 2 contents which imply entrapment pressures that are significantly lower than those obtained from independent petrological barometers. Furthermore, a global database of melt inclusion compositions from low H 2 O settings, indicates that the distribution of saturation pressures varies surprisingly little between mid-ocean ridges, ocean islands, and continental rift zones. 95% of the inclusions in the database have saturation pressures of 200 MPa or less, indicating that melt inclusion CO 2 does not generally provide an accurate estimate of magma chamber depths. A model of the P-V-T-X evolution of olivine-hosted melt inclusions was developed so that the properties of the inclusion system could be tracked as the hosts follow a model P-T path. The models indicate that the principal control on the saturation of CO 2 in the inclusion and the formation of vapor bubbles is the effect of postentrapment crystallization on the major element composition of the inclusions and how this translates into variation in CO 2 solubility. The pressure difference between external melt and the inclusion is likely to be sufficiently high to cause decrepitation of inclusions in most settings. Decrepitation can account for the apparent mismatch between CO 2 -based barometry and other petrological barometers, and can also account for the observed global distribution of saturation pressures. Only when substantial postentrapment crystallization occurs can reconstructed inclusion compositions provide an accurate estimate of magma chamber depth.

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Quantification of the CO 2 budget and H 2 O–CO 2 systematics in subduction-zone magmas through the experimental hydration of melt inclusions in olivine at high H 2 O pressure

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Cited by 89 publications

References 50 publications

Subducting carbon

Subducting carbon

A revised budget for Cenozoic sedimentary carbon subduction

Bubble formation and decrepitation control theCO₂content of olivine‐hosted melt inclusions

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Quantification of the CO 2 budget and H 2 O–CO 2 systematics in subduction-zone magmas through the experimental hydration of melt inclusions in olivine at high H 2 O pressure

Abstract: HIGHLIGHTS:

Cited by 89 publications

References 50 publications

Subducting carbon

Subducting carbon

A revised budget for Cenozoic sedimentary carbon subduction

Bubble formation and decrepitation control theCO2content of olivine‐hosted melt inclusions

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Product

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Bubble formation and decrepitation control theCO₂content of olivine‐hosted melt inclusions