3 results on '"Caldera cycles"'
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2. Tracking timescales of magma reservoir recharge through caldera cycles at Santorini (Greece). Emphasis on an explosive eruption of Kameni Volcano
- Author
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Polo-Sánchez, Antonio, Flaherty, Taya, Hervé, Garance, Druitt, Tim, Fabbro, Gareth, Nomikou, Paraskevi, Balcone-Boissard, Helène, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Departamento de Geología [Salamanca], Universidad de Salamanca, School of Environmental Sciences [Norwich], University of East Anglia [Norwich] (UEA), Department of Geology and Geoenvironment, National and Kapodistrian University of Athens (NKUA), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), and ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016)
- Subjects
caldera cycles ,pyroxene ,Santorini ,diffusion timescales ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,diffusion timescales Kameni Santorini caldera cycles pyroxene ,Kameni - Abstract
Pre-eruptive processes and their timescales are critical information for risk management at explosive volcanoes, and Santorini caldera (Greece) provides an excellent context in which to approach this subject. We ask two questions. First, are pre-eruptive processes the same for small and big eruptions? To investigate, we performed a multi-mineral diffusion timescale study of a small explosive eruption of Kameni Volcano and compared the results with those published for larger caldera-forming eruptions at Santorini. The Kameni dacite resembles products of larger eruptions in being crystal-poor, containing plagioclase with antecrystic cores and autocrystic rims, bearing orthopyroxene with sector zoning and phantom skeletal morphologies, and showing evidence for mixing of different silicic magmas prior to eruption. Diffusion timescales from Mg-Fe profiles in orthopyroxene and clinopyroxene phenocrysts are
- Published
- 2023
3. Tracking caldera cycles in the Aso magmatic system - Applications of magnetite composition as a proxy for differentiation
- Author
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Keller, Franziska, Guillong, Marcel, Geshi, Nobuo, Miyakawa, Ayumu, and Bachmann, Olivier
- Subjects
Magnetite ,Silicic volcanism ,Caldera cycles ,Super eruption ,Magma evolution ,Aso caldera ,Geophysics ,Geochemistry and Petrology - Abstract
Caldera-forming eruptions are among the most hazardous natural events on Earth and pose a significant risk for global consequences in the future. Recent petrological re-evaluations of pre-, syn-, and post-caldera deposits in several volcanic systems worldwide suggest a cyclic behavior in the evolution of the subvolcanic reservoirs feeding these eruptions. Such caldera cycles are usually subdivided into maturation, fermentation and recovery phases, each characterized by distinct petrological features (e.g. variations in mineral and glass compositions). Combined with trends in intensive parameters and geophysical information about the eruptive behavior of the system, these characteristics can be used to determine the current state of a reservoir within the caldera cycle framework. Here, we test the application of this caldera cycle model on the Aso volcanic complex in Central Kyushu (Japan) by analyzing pre-, syn-, and post-caldera activity between the Aso-4 and Aso-3 events and evaluate the recent activity of Aso based on mineral and glass geochemistry. Widely overlapping compositions in most minerals (here plagioclase and orthopyroxene) and melt, as well as similar ranges in intensive parameters (e.g. magmatic H2O content), make it difficult to pinpoint chemical differences between pre-or post-caldera eruptions. Tracing the MnO/Al2O3 ratio in titanomagnetite, on the other hand, appears as a useful proxy to trace the level of differentiation within the reservoir prior to eruption. Titanomagnetite is an abundant mineral phase known to chemically re-equilibrate fast with melt and hence records "average" conditions prevailing just prior to eruption, with MnO showing a typical incompatible behavior during magma evolution, while Al2O3 is typically compatible. The assessment of different case studies revealed clear evolutionary patterns common in all these caldera cycles with low Mn (associated with low levels of differentiation) during recovery, progressively increasing during maturation, and culminating at highest levels (and associated levels of differentiation) during the fermentation phase, right before the next caldera-forming event. The MnO/Al2O3 ratio in titanomagnetite is analytically easy and quick to determine by electron microprobe, and gives valuable information about the current position of a system within the caldera cycle framework. Based on the evaluation of recent eruptive products in context with the current volcanic activity, we conclude that Aso is presently still in recovery after the massive Aso-4 eruption. Depending on magma supply from depth, the system can either enter renewed matu-ration or activity could decline leading to the cessation of the system., Journal of Volcanology and Geothermal Research, 436, ISSN:0377-0273
- Published
- 2023
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