[Parameters: Topic='SOLID EARTH', Term='GEOCHEMISTRY', Variable_Level_1='BIOGEOCHEMISTRY']
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Geochemical analyses of volcanic bombs erupted from Mount Erebus Entry ID: Erebus_petrology |
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Summary
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Abstract:
This data set consists of geochemical analyses of volcanic bombs erupted from Mount Erebus between 1972 and 2004 and selected older lava samples from the summit area. Detailed electron microprobe analyses of minerals in the volcanic bombs are given in Appendix. Mount Erebus, Ross Island, Antarctica, is a large (3794 m) alkaline open-conduit stratovolcano that hosts a persistently convecting and degassing lake of anorthoclase-phyric phonolite magma. The composition of the lava (magma) lake over the last 31 years was investigated by examining glass and mineral compositions in lava bombs erupted between December 1972 and January 2004. Olivine, clinopyroxene, titanomagnetite, fluor-apatite, and matrix glass compositions are invariant and show that the magmatic temperature (~1000°C) and oxygen fugacity (ΔlogFMQ = -0.9) have been constant. Anorthoclase phenocrysts up to 10 cm in length show complex textural and compositional zoning that reflects growth during convection in a PH2O gradient under isothermal conditions. Bomb textures and anorthoclase compositions suggest that crystallization occurs at low degrees of effective undercooling and is controlled by shallow degassing of water in the conduit. Minor variations in eruptive activity in the last 31 years are decoupled from magma compositions. The variations probably relate to changes in conduit geometry within the volcano and/or variable input of CO2-rich volatiles into the upper-level magma chamber from deeper in the system. Eleven bulk samples of phonolite lava from the summit plateau that range in age from 0 ± 4 ka to 17 ± 8 ka were analyzed for major and trace elements. Small compositional variations are controlled by anorthoclase content. The lavas are indistinguishable from modern bulk tephra compositions and demonstrate that Mt. Erebus has been erupting lava and tephra from the summit region with the same bulk composition for ~17 ka. |
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Description: Representative analyses of volcanic rocks from Mt. Erebus |
Location Keywords
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CONTINENT
> ANTARCTICA
GEOGRAPHIC REGION > POLAR |
Science Keywords
| SOLID EARTH >GEOCHEMISTRY >BIOGEOCHEMICAL PROCESSES [Definition] |
| SOLID EARTH >TECTONICS >VOLCANIC ACTIVITY >ERUPTION DYNAMICS >MAGMA COMPOSITION/TEXTURE [Definition] |
ISO Topic Category
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GEOSCIENTIFIC INFORMATION
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Data Center
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Mount Erebus Volcano Observatory, Earth and Environmental Science Department, New Mexico Institute of Mining and Technology
[Information]
Data Center URL: http://www.ees.nmt.edu/Geop/Erebus/erebus.html Dataset ID: Kelly
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Personnel
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PHILIP
R.
KYLE Role: INVESTIGATOR Phone: 505 835-5995 Fax: 505 835-6436 Email: kyle at nmt.edu Contact Address: Department of Earth and Environmental Science New Mexico Institute of Mining and Technology 801 Leroy Place City: Socorro Province or State: NM Postal Code: 87801-4796 Country: USA |
Publications/References
Kyle, P.R., Moore, J.A., and Thirlwall, M.F., 1992, Petrologic evolution of
anorthoclase phonolite lavas at Mount Erebus, Ross Island, Antarctica: Journal
of Petrology, v. 33, p. 849-875.
anorthoclase phonolite lavas at Mount Erebus, Ross Island, Antarctica: Journal
of Petrology, v. 33, p. 849-875.
Creation and Review Dates
DIF Creation Date:
2006-07-18
Last DIF Revision Date:
2010-07-02
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