Reconstruction of melt inclusion minimum CO2 contents from the fire fountaining phase of the 2021 Fagradalsfjall eruption, Iceland
During the 2021 Fagradalsfjall eruption, the magma effusion rate, originally low, increased greatly with lava fountaining commencing 27 April 2021. In this project, major element compositions of melt inclusions and their host minerals erupted on 28 April 2021 at Fagradalsfjall are presented along wi...
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| Format: | Bachelor Thesis |
| Language: | English |
| Published: |
2023
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| Online Access: | http://hdl.handle.net/1946/44492 |
| Summary: | During the 2021 Fagradalsfjall eruption, the magma effusion rate, originally low, increased greatly with lava fountaining commencing 27 April 2021. In this project, major element compositions of melt inclusions and their host minerals erupted on 28 April 2021 at Fagradalsfjall are presented along with Raman spectroscopy measured CO2 densities contained within melt inclusion fluid bubbles. Analysis of the chemical compositions of melt inclusions provides a snapshot of the compositional diversity contained within a magmatic system. Further, since CO2 exsolves from the melt phase upon reaching lower pressures, the CO2 density of fluid bubbles in melt inclusions can be used to estimate the minimum amount of CO2 dissolved in the glass phase of a melt inclusion upon entrapment and its corresponding fluid saturation pressure. The melt inclusions erupted 28 April 2021 during the fire fountaining phase of the eruption underwent 0-10% post entrapment crystallization. Magmatic compositional variability is demonstrated by the melt inclusions in this study by the large range (0.02-0.13) of K2O/TiO2 values which encompass the relatively depleted compositional range analyzed over the course of the 2021 eruption. The minimum amount of CO2 dissolved in the melt inclusion at the time of entrapment is between 5-2200 ppm and the fluid saturation pressures are between 0.01-4.0 kbar. Both the CO2 contents and the fluid saturation pressure estimates obtained for 28 April compositions correspond closely with compositions erupted on the second day of the 2021 Fagradalsfjall eruption. The pressure estimates are generally lower than expected for the fire fountaining phase of the eruption. The lower pressure estimates may be due to neglecting the dissolved CO2 in the melt phase of the melt inclusion and only considering fluid bubble CO2 contents. Rennsli kviku í Fagradalsgosinu 2021 var lítið í byrjun en jókst síðan verulega og kvikustrókavirkni byrjaði 27. apríl 2021. Í þessu verkefni var greind aðalefnasamsetning innlyksna og kristalla ... |
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