Clinopyroxene Dissolution Records Rapid Magma Ascent
Magma ascent rates control volcanic eruption styles. However, the rates at which basaltic magmas ascend through the crust remain highly uncertain. Although recent studies have successfully exploited records of decompression driven degassing to estimate the rates at which H2O-rich basalts ascend, suc...
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Online Access: | https://doi.org/10.3389/feart.2020.00188 https://doaj.org/article/f5f5ac7d83fb4b2e831a7e738493ca31 |
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ftdoajarticles:oai:doaj.org/article:f5f5ac7d83fb4b2e831a7e738493ca31 2023-05-15T16:49:06+02:00 Clinopyroxene Dissolution Records Rapid Magma Ascent David A. Neave John Maclennan 2020-06-01T00:00:00Z https://doi.org/10.3389/feart.2020.00188 https://doaj.org/article/f5f5ac7d83fb4b2e831a7e738493ca31 EN eng Frontiers Media S.A. https://www.frontiersin.org/article/10.3389/feart.2020.00188/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.00188 https://doaj.org/article/f5f5ac7d83fb4b2e831a7e738493ca31 Frontiers in Earth Science, Vol 8 (2020) magma ascent rate plumbing system clinopyroxene dissolution basalt disequilibrium Iceland Science Q article 2020 ftdoajarticles https://doi.org/10.3389/feart.2020.00188 2022-12-31T11:57:46Z Magma ascent rates control volcanic eruption styles. However, the rates at which basaltic magmas ascend through the crust remain highly uncertain. Although recent studies have successfully exploited records of decompression driven degassing to estimate the rates at which H2O-rich basalts ascend, such approaches cannot readily be applied to primitive and H2O-poor basalts that erupt in ocean island and mid-ocean ridge settings. Here we present magma ascent rates obtained by modeling the dissolution of clinopyroxene crystals in a wehrlitic nodule from the primitive Borgarhraun lava flow in North Iceland. High-Al2O3 clinopyroxene core compositions are consistent with crystallization near the Moho (~800 MPa), whereas low-Al2O3 clinopyroxene rims and inclusion compositions are consistent with crystallization at or near the surface. We interpret low-Al2O3 rims and inclusions as the crystallized remnants of boundary layers formed by the dissolution of high-Al2O3 clinopyroxene during magma ascent. By combining characteristic rim dissolution lengths of 50–100 μm with published experimental calibrations of clinopyroxene dissolution behavior, we estimate that the Borgarhraun magma most likely decompressed and ascended at rates of 3.0–15 kPa.s−1 and 0.11–0.53 m.s−1, respectively. These rates are slightly faster than published estimates obtained by modeling the diffusive re-equilibration of olivine crystals, suggesting that the Borgarhraun magma either accelerated upwards or that it stalled briefly at depth prior to final ascent. Comparisons with other basaltic eruptions indicate that the H2O-poor magma that fed the dominantly effusive Borgarhraun eruption ascended at a similar rate to some H2O-rich magmas that have fed explosive eruptions in arc settings. Thus, magma ascent rates do not appear to correlate simply with magma H2O contents. Overall, our findings confirm that primitive and H2O-poor basalts can traverse the crust within days, and may erupt with little precursory warning of magma ascent. Article in Journal/Newspaper Iceland Ocean Island Directory of Open Access Journals: DOAJ Articles Borgarhraun ENVELOPE(-17.022,-17.022,65.810,65.810) Frontiers in Earth Science 8 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
magma ascent rate plumbing system clinopyroxene dissolution basalt disequilibrium Iceland Science Q |
spellingShingle |
magma ascent rate plumbing system clinopyroxene dissolution basalt disequilibrium Iceland Science Q David A. Neave John Maclennan Clinopyroxene Dissolution Records Rapid Magma Ascent |
topic_facet |
magma ascent rate plumbing system clinopyroxene dissolution basalt disequilibrium Iceland Science Q |
description |
Magma ascent rates control volcanic eruption styles. However, the rates at which basaltic magmas ascend through the crust remain highly uncertain. Although recent studies have successfully exploited records of decompression driven degassing to estimate the rates at which H2O-rich basalts ascend, such approaches cannot readily be applied to primitive and H2O-poor basalts that erupt in ocean island and mid-ocean ridge settings. Here we present magma ascent rates obtained by modeling the dissolution of clinopyroxene crystals in a wehrlitic nodule from the primitive Borgarhraun lava flow in North Iceland. High-Al2O3 clinopyroxene core compositions are consistent with crystallization near the Moho (~800 MPa), whereas low-Al2O3 clinopyroxene rims and inclusion compositions are consistent with crystallization at or near the surface. We interpret low-Al2O3 rims and inclusions as the crystallized remnants of boundary layers formed by the dissolution of high-Al2O3 clinopyroxene during magma ascent. By combining characteristic rim dissolution lengths of 50–100 μm with published experimental calibrations of clinopyroxene dissolution behavior, we estimate that the Borgarhraun magma most likely decompressed and ascended at rates of 3.0–15 kPa.s−1 and 0.11–0.53 m.s−1, respectively. These rates are slightly faster than published estimates obtained by modeling the diffusive re-equilibration of olivine crystals, suggesting that the Borgarhraun magma either accelerated upwards or that it stalled briefly at depth prior to final ascent. Comparisons with other basaltic eruptions indicate that the H2O-poor magma that fed the dominantly effusive Borgarhraun eruption ascended at a similar rate to some H2O-rich magmas that have fed explosive eruptions in arc settings. Thus, magma ascent rates do not appear to correlate simply with magma H2O contents. Overall, our findings confirm that primitive and H2O-poor basalts can traverse the crust within days, and may erupt with little precursory warning of magma ascent. |
format |
Article in Journal/Newspaper |
author |
David A. Neave John Maclennan |
author_facet |
David A. Neave John Maclennan |
author_sort |
David A. Neave |
title |
Clinopyroxene Dissolution Records Rapid Magma Ascent |
title_short |
Clinopyroxene Dissolution Records Rapid Magma Ascent |
title_full |
Clinopyroxene Dissolution Records Rapid Magma Ascent |
title_fullStr |
Clinopyroxene Dissolution Records Rapid Magma Ascent |
title_full_unstemmed |
Clinopyroxene Dissolution Records Rapid Magma Ascent |
title_sort |
clinopyroxene dissolution records rapid magma ascent |
publisher |
Frontiers Media S.A. |
publishDate |
2020 |
url |
https://doi.org/10.3389/feart.2020.00188 https://doaj.org/article/f5f5ac7d83fb4b2e831a7e738493ca31 |
long_lat |
ENVELOPE(-17.022,-17.022,65.810,65.810) |
geographic |
Borgarhraun |
geographic_facet |
Borgarhraun |
genre |
Iceland Ocean Island |
genre_facet |
Iceland Ocean Island |
op_source |
Frontiers in Earth Science, Vol 8 (2020) |
op_relation |
https://www.frontiersin.org/article/10.3389/feart.2020.00188/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.00188 https://doaj.org/article/f5f5ac7d83fb4b2e831a7e738493ca31 |
op_doi |
https://doi.org/10.3389/feart.2020.00188 |
container_title |
Frontiers in Earth Science |
container_volume |
8 |
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1766039175634616320 |