Reconstructing the deep CO2 degassing behaviour of large basaltic fissure eruptions

Hartley, Margaret E.; Maclennan, J.; Edmonds, Marie; Thordarson, T.

doi:10.1016/j.epsl.2014.02.031

Cited by 172 publications

(208 citation statements)

References 55 publications

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“…The detection limit of CO 2 in inclusion-hosted bubbles is better than 0.04 g/cm 3 based on analysis of CO 2 -bearing samples on the same instrument (Hartley et al 2014).…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…If inclusion-hosted bubbles remain in equilibrium with coexisting trapped melts during cooling; then, CO 2 may be transferred into inclusion-hosted bubbles (Roedder 1979;Anderson and Brown 1993;Steele-Macinnis et al 2011;Bucholz et al 2013;Hartley et al 2014;Moore et al 2015). However, assuming that bubble-melt equilibrium is maintained within cooling, inclusions may not always be valid: rapid quenching kinetically inhibits CO 2 diffusion, resulting in reduced sequestration of CO 2 into bubbles (Neave et al 2014a;Wallace et al 2015).…”

Section: Inclusion-hosted Bubblesmentioning

confidence: 99%

“…Gurenko and Chaussidon 1995;Thordarson et al 1996;Gurenko and Sobolev 2006;Maclennan 2008aMaclennan , 2008bHartley et al 2014). Most of these studies used olivine-hosted inclusions, the major element contents of which are susceptible to post-entrapment modification that obscures primitive melt compositions (Gaetani and Watson 2000;Danyushevsky et al 2002).…”

Section: Introduction Primitive Melts In the Eastern Volcanic Zone Ofmentioning

confidence: 99%

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The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Neave

Maclennan

Thordarson

et al. 2015

Contrib Mineral Petrol

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evolved assemblage is close to being in equilibrium with the matrix glass, trace element disequilibrium between primitive and evolved assemblages indicates that they were derived from different distributions of mantle melt compositions. Juxtaposition of disequilibrium assemblages probably occurred during disaggregation of incompatible trace element-depleted mushes (mean La/Yb melt = 2.1) into aphyric and incompatible trace element-enriched liquids (La/Yb melt = 3.6) shortly before the growth of the evolved macrocryst assemblage. Post-entrapment modification of plagioclase-hosted melt inclusions has been minimal and high-Mg# inclusions record differentiation and mixing of compositionally variable mantle melts that are amongst the most primitive liquids known from the EVZ. Coupled highfield strength element (HFSE) depletion and incompatible trace element enrichment in a subset of primitive plagioclase-hosted melt inclusions can be accounted for by inclusion formation following plagioclase dissolution driven by interaction with plagioclase-undersaturated melts. Thermobarometric calculations indicate that final crystal-melt equilibration within the evolved assemblage occurred at ~1140 °C and 0.0-1.5 kbar. Considering the large volume of the erupted tephra and textural evidence for rapid crystallisation of the evolved assemblage, 0.0-1.5 kbar is considered unlikely to represent a pressure of long-term magma accumulation and storage. Multiple thermometers indicate that the primitive assemblage crystallised at high temperatures of 1240-1300 °C. Different barometers, however, return markedly different crystallisation depth estimates. Raw clinopyroxene-melt pressures of 5.5-7.5 kbar conflict with apparent melt inclusion entrapment pressures of 1.4 kbar. After applying a correction derived from published experimental data, clinopyroxene-melt equilibria return mid-crustal pressures of 4 ± 1.5 kbar, which are consistent with pressures estimated from the major element Abstract Major, trace and volatile elements were measured in a suite of primitive macrocrysts and melt inclusions from the thickest layer of the 10 ka Grímsvötn tephra series (i.e. Saksunarvatn ash) at Lake Hvítárvatn in central Iceland. In the absence of primitive tholeiitic eruptions (MgO > 7 wt%) within the Eastern Volcanic Zone (EVZ) of Iceland, these crystal and inclusion compositions provide an important insight into magmatic processes in this volcanically productive region. Matrix glass compositions show strong similarities with glass compositions from the AD 1783-1784 Laki eruption, confirming the affinity of the tephra series with the Grímsvötn volcanic system. content of primitive melt inclusions. Long-term storage of primitive magmas in the mid-crust implies that low CO 2 concentrations measured in primitive plagioclase-hosted inclusions (262-800 ppm) result from post-entrapment CO 2 loss during transport through the shallow crust. In order to reconstruct basaltic plumbing system geometries from petrological data with greater confidence, mineral-mel...

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“…The detection limit of CO 2 in inclusion-hosted bubbles is better than 0.04 g/cm 3 based on analysis of CO 2 -bearing samples on the same instrument (Hartley et al 2014).…”

Section: Raman Spectroscopymentioning

confidence: 99%

Section: Inclusion-hosted Bubblesmentioning

confidence: 99%

Section: Introduction Primitive Melts In the Eastern Volcanic Zone Ofmentioning

confidence: 99%

See 1 more Smart Citation

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Neave

Maclennan

Thordarson

et al. 2015

Contrib Mineral Petrol

Self Cite

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“…Other typical indicators of lava-water interaction such as peperite, hyaloclastites and pillow lavas are entirely absent from the observed outcrop, and all current observation indicates that these lavas were erupted into an unequivocally terrestrial environment. Thordarson and Self (1993) b c Hartley et al (2014) d Tolan et al (1989) e Thordarson and Self (1998) f g Self et al (2006) …”

Section: Interactions With Watermentioning

confidence: 99%

“…Given the modern atmosphere contains ~3 × 10 6 Tg CO2 (Self et al, 2006), total instantaneous release from the entire BRM would increase CO2 by up to 7%, however, since 32 the Cambrian atmosphere was around 15 times more enriched in background CO2 (Crowley and Berner, 2001), BRM CO2 output in an theoretical instantaneous snapshot would contribute < 0.5% of the total atmospheric CO2 at the time of eruption. Laki emitted at least 3.04 × 10 2 Tg CO2 (Hartley et al, 2014) whilst the Roza flow, a single constituent of the Columbia River Basalts, contributed 1.43 x 10 4 Tg CO2 (calculated by Eq. (2)) to the Neogene atmosphere, a value similar to those estimated for the BRM.…”

Section: Carbon Dioxide (Co2)mentioning

confidence: 99%

The Giant Lavas of Kalkarindji: rubbly pāhoehoe lava in an ancient continental flood basalt province

Marshall

Widdowson

Murphy

2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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The Kalkarindji continental flood basalt province of northern Australia erupted in the mid Cambrian . It now consists of scattered basaltic lava fields, the most extensive being the Antrim Plateau Volcanics (APV) -a semi-continuous outcrop (c. 50,000 km 2 ) reaching a maximum thickness of 1.1 km. Cropping out predominately in the SW of the APV, close to the top of the basalt succession, lies the Blackfella Rockhole Member (BRM). Originally described as 'basaltic agglomerate' the BRM has, in recent years, been assumed to be explosive tephra of phreatomagmatic origin, thus providing a potent vehicle for volatile release to the upper atmosphere. Our detailed field investigations reveal that this basaltic agglomerate is, in reality, giant rubble collections (15 -20 m thick) forming the upper crusts of rubbly pāhoehoe lava units 25 -40 m thick; covering 18,000 -72,000 km 2 and an estimated volume of 1,500 -19,200 km 3 . These flows, rheologically but not chemically, distinct from the majority of Kalkarindji lavas, indicate a fundamental change in eruption dynamics. A low volatile content, induced high amounts of pre-eruptive degassing causing super-cooling and an increase in crystal nucleation and viscosity. A more viscous lava and a consistently faster rate of effusion (analogous to that of Laki, Iceland) created the flow dynamics necessary to disturb the lava crust to the extent seen in the BRM. Volatile release is estimated at 1.65 × 10 4 -2.11 × 10 5 Tg total CO2 at a rate of 867 Tg a -1 and 9.07 × 10 3 -1.16 × 10 5 Tg SO2 at 476.50 Tg a -1 . These masses accounted for 0.5% of Cambrian atmospheric conditions whilst limiting factors reduced the effect of volatile delivery to the atmosphere, thus any potential global impact caused by these flows alone was minimal.

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Water‐rich and volatile‐undersaturated magmas at Hekla volcano, Iceland

Lucic

Berg

Stix

2016

Geochem Geophys Geosyst

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Olivine‐hosted melt inclusions from four eruptions at Hekla volcano in Iceland were analyzed for their dissolved H2O, CO2, S, and Cl contents. A positive correlation among the repose interval, magmatic evolution, and volatile contents of magmas is revealed. H2O is the dominant volatile species; it behaves as an incompatible component, increasing in concentration over time as a result of fractional crystallization in the magma. The full suite of H2O contents ranges from a low of 0.80 wt % in basaltic andesites to a maximum of 5.67 wt % in rhyolites. Decreasing H2O/K2O at fixed major element compositions suggests that syneruptive degassing reduces H2O contents significantly. Hekla magmas are CO2 poor, with very low concentrations present only in the most evolved compositions (∼20–30 ppm or less). The decrease in S content from basaltic andesite to rhyolite demonstrates that sulfide saturation is attained when the melt composition reaches basaltic andesite, resulting in the precipitation of pyrrhotite. Low CO2/Nb ratios suggest that vapor saturation is most likely reached during an early period of cooling and solidification in the crust. Fresh injections of mafic magma interact with previously solidified intrusives, producing new melts that are volatile undersaturated. Vapor saturation pressures obtained using the most volatile‐rich melt inclusions suggest the presence of a magma chamber at a minimum depth of ∼7 km. This is in agreement with geophysical observations from recent small‐volume eruptions, but given the possibility of volatile‐undersaturated melts, some of the magmas may reside at greater depths.

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Reconstructing the deep CO2 degassing behaviour of large basaltic fissure eruptions

Cited by 172 publications

References 55 publications

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

The Giant Lavas of Kalkarindji: rubbly pāhoehoe lava in an ancient continental flood basalt province

Water‐rich and volatile‐undersaturated magmas at Hekla volcano, Iceland

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