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Data Processing Methods for 3D Seismic Imaging of Subsurface Volcanoes: Applications to the Tarim Flood Basalt
Published on: August 7, 2017
Deep crustal assimilation during the 2021 Fagradalsfjall Fires, Iceland
James M D Day1, Savannah Kelly2, Valentin R Troll3,4
1Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA. jmdday@ucsd.edu.
The 2021 Fagradalsfjall eruption lavas show significant crustal contamination, unlike the typical 2022 lavas. This indicates initial magma stalling and assimilation, followed by efficient magma transport in subsequent eruptions.
Area of Science:
- Geochemistry
- Volcanology
- Isotope Geology
Background:
- Active basaltic eruptions offer opportunities for time-series analysis of geochemical and geophysical data.
- The Fagradalsfjall and Sundhnúkur volcanic activity on Iceland's Reykjanes Peninsula since 2021 provides a unique case study.
- Previous interpretations suggested earliest lavas solely reflected deeper mantle source processes.
Purpose of the Study:
- To investigate the geochemical composition of lavas from the 2021 Fagradalsfjall eruption.
- To determine the role of fractional crystallization and crustal contamination in the earliest eruptive products.
- To compare the geochemical signatures of the 2021 and 2022 lavas to understand changes in eruption processes.
Main Methods:
- Analysis of osmium (Os) isotopes in volcanic lavas.
- Measurement of platinum (Pt) and iridium (Ir) concentrations.
- Comparison of isotopic and elemental ratios with known Icelandic and global basaltic lavas.
Main Results:
- The 2021 Fagradalsfjall lavas exhibit highly anomalous osmium isotope ratios and platinum/iridium ratios, indicative of significant crustal contamination.
- Contamination was likely caused by assimilation of mid-ocean-ridge gabbros and older basalts.
- The 2022 lavas display typical Icelandic basaltic compositions, with no evidence of crustal contamination.
Conclusions:
- The initiation of the 2021 Fagradalsfjall eruption involved pre-eruptive magma stalling, fractional crystallization, and assimilation of crustal materials.
- An established magmatic conduit system in 2022 facilitated efficient magma ascent without significant crustal assimilation.
- Osmium isotopes are powerful tracers for identifying crustal contamination in active volcanic systems.
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