Taking the pulse of volcanic eruptions using plagioclase glomerocrysts
| Autor: | Cyril Chelle-Michou, Anders McCarthy, Stéphane Escrig, Pierre Vonlanthen, Jonathan D. Blundy, Anders Meibom |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
010504 meteorology & atmospheric sciences
crystallization Pluton volatile-fluxing engineering.material 010502 geochemistry & geophysics 01 natural sciences orbicules and comb layering pressure Geochemistry and Petrology sierra-nevada intermediate Earth and Planetary Sciences (miscellaneous) Plagioclase fractionation phosphorus Petrology Tolbachik volcano Plagioclase glomerocryst Rapid crystal growth Volatile-fluxing Nano-SIMS Orbicules and comb layering 0105 earth and related environmental sciences Melt inclusions geography Olivine geography.geographical_feature_category model tolbachik volcano strontium diffusion Strombolian eruption rapid crystal growth Igneous rock plagioclase glomerocryst Geophysics Volcano 13. Climate action Space and Planetary Science engineering melts nano-sims magmatic processes Layering Geology |
| Zdroj: | Earth and Planetary Science Letters, vol. 552, pp. 1-12 (AN 116596) Earth and Planetary Science Letters, 552 |
| Popis: | Crystallization timescales in subvolcanic systems and the consequences of interaction between ascending magmas and gases remain largely unconstrained, as do links between these processes and monitoring signals at restless volcanoes. We apply diffusion chronometry to radially-oriented plagioclase and associated olivine in a glomerocryst from Tolbachik volcano (Kamchatka, Russia) to elucidate such processes. We show that cm-size glomerocrysts grow in a few days prior to, or during, eruption. Melt inclusions from these glomerocrysts show no compositional evolution during crystallization, implying growth in a melt-rich and dynamic environment. Volatile elements in melt inclusions show significant variability, with increasing CO2 as H2O decreases. This behaviour is inconsistent with normal degassing processes, and more likely reflects CO2-fluxing. On the basis of short residence timescales of glomerocrysts and sharp changes in melt inclusion volatile abundances, we propose that rapid (pre-)eruptive crystallization is controlled by rhythmic fluxing of magmatic H2O and CO2 through the sub-volcanic conduit. This implies that compositional zoning in plagioclase, from resorption textures to oscillatory zoning, record short-term CO2- and H2O-fluxing episodes, consistent with strombolian eruption dynamics. We propose that volcanic glomerocrysts represent the counterpart of vertical igneous layering (or comb layering) in shallow plutons. Magmatic layering and glomerocrysts dominated by radial plagioclase offer novel ways of targeting short-term crystallization and degassing processes in subvolcanic systems. (C) 2020 The Author(s). Published by Elsevier B.V. |
| Databáze: | OpenAIRE |
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