Reconstructing CO2 concentrations in basaltic melt inclusions using Raman analysis of vapor bubbles

Aster, Ellen; Wallace, Paul; Moore, Lowell R.; Watkins, James M.; Gazel, Esteban; Bodnar, Robert J.

doi:10.1016/j.jvolgeores.2016.04.028

Cited by 71 publications

(120 citation statements)

References 40 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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“…Postentrapment crystallization may also play a role in formation of these bubbles [ Roedder , ]. Crystallization of olivine on the inclusion walls simultaneously lowers the pressure and raises the CO 2 content in the liquid of the inclusion, favoring saturation [ Steele‐Macinnis et al ., ; Sides et al ., ; Aster et al ., ]. Another important feature of postentrapment crystallization is that it modifies the major element composition of the melt.…”

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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“…Alternatively, melt contraction during cooling could result in low internal vesicle pressures and lower than expected gas densities. Studies on vapor bubbles in melt inclusions have shown that melt contraction in a fixed-volume system may lead to an increase in the volume of bubbles during quenching, and consequently low gas densities (e.g., Aster et al, 2016). According to the model for melt density provided by Lange (1994), melt contraction in a fixed volume system would increase the observed vesicularity by up to 2 vol.% during cooling from 1200°C to 826°C.…”

Section: Calculating Total Co2 Concentrations In Morbmentioning

confidence: 99%

“…The instrument is equipped with a thermoelectrically cooled (−70 ºC) Synapse ® 1024x256 pixel open electrode CCD detector. Measurements were conducted following previously established protocols (Aster et al, 2016;Esposito et al, 2011;Lamadrid et al, 2017;Moore et al, 2015). All analyses were conducted with a 100x long working distance objective with a numerical aperture (NA) of 0.8 and a confocal hole diameter set to 300 µm.…”

Section: Vesicularity Vesicle Size Distributions and Exsolved Volatmentioning

confidence: 99%

Geophysical and geochemical constraints on submarine volcanic processes

Jones¹

2019

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Submarine volcanic systems form new oceanic crust, host unique chemosynthetic ecosystems, concentrate rare metals, and provide a conduit for chemical transfer from the Earth's interior to hydrosphere. Although our understanding of submarine volcanoes has been historically limited due to their relative inaccessibility, recent observations from active systems provide valuable opportunities to address key open questions in submarine volcanology. This thesis provides new insight into submarine volcanic processes using observations and samples from the 2011 Axial Seamount eruption, the 2012 Havre Volcano eruption, and the Mid-Atlantic Ridge near 14°N. In Chapter 2, I develop best practices for quantifying vesicle textures and reconstructing total CO2 concentrations in mid-ocean ridge basalts (MORB). Based on synthetic vesicle populations, 2D and 3D measurements, and Raman spectroscopy, I show that traditional methods overestimate MORB CO2 concentrations by as much as 50%, which has important implications for estimating ridge CO2 flux. In Chapter 3, I apply methods from Chapter 2, along with a bubble growth model, to samples from the 2011 Axial Seamount eruption in order to evaluate magma ascent and lava flow rates. I show that the variability in ascent rates during the 2011 eruption spans the range previously proposed over the global mid-ocean ridge system. I suggest that the variability in ascent rates relates to lateral dike propagation and evolving reservoir overpressures and that ascent rates influence flow morphology. In Chapter 4, I address the origin of highly vesicular MORB that pop upon recovery from the seafloor. I show that bubble accumulation produces the high volatile concentrations in these popping rocks and demonstrate that mantle carbon concentrations are lower and less heterogeneous than previously proposed. In Chapter 5, I evaluate models for the submarine dispersal of giant pumice clasts using observations from the 2012 Havre Volcano eruption. I show that the seafloor distribution of giant pumice is controlled by conductive cooling, the advective displacement of steam by water through highly permeable pathways, and clast breakup during transport and deposition. Together, these chapters provide critical constraints on the flux of volatiles at mid-ocean ridges and the processes governing the emplacement of volcanic products on the seafloor.

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Reconstructing CO2 concentrations in basaltic melt inclusions using Raman analysis of vapor bubbles

Cited by 71 publications

References 40 publications

Subducting carbon

Subducting carbon

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

Geophysical and geochemical constraints on submarine volcanic processes

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Reconstructing CO2 concentrations in basaltic melt inclusions using Raman analysis of vapor bubbles

Cited by 71 publications

References 40 publications

Subducting carbon

Subducting carbon

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

Geophysical and geochemical constraints on submarine volcanic processes

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