The Role of Volatiles in the Genesis, Evolution and Eruption of Arc Magmas

The Role of Volatiles in the Genesis, Evolution and Eruption of Arc Magmas PDF

Author: G.F. Zellmer

Publisher: Geological Society of London

Published: 2015-03-17

Total Pages: 294

ISBN-13: 1862396892

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The subduction zone volatile cycle is key to understanding the petrogenesis, transport, storage and eruption of arc magmas. Volatiles control the flux of slab components into the mantle wedge, are responsible for melt generation through lowering the solidi of mantle materials and influence the crystallizing phase assemblages in the overriding crust. Further, the rates and extents of degassing during magma storage and decompression affect magma rheology, ultimately control eruption style and have consequences for the environmental impact of explosive arc volcanism. This book highlights recent progress in constraining the role of volatiles in magmatic processes. Individual book sections are devoted to tracing volatiles from the subducting slab to the overriding crust, their role in subvolcanic processes and eruption triggering, as well as magmatic-hydrothermal systems and volcanic degassing. For the first time, all aspects of the overarching theme of volatile cycling are covered in detail within a single volume.

Volatiles in Magmas

Volatiles in Magmas PDF

Author: Michael R. Carroll

Publisher: Walter de Gruyter GmbH & Co KG

Published: 2018-12-17

Total Pages: 536

ISBN-13: 1501509675

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Volume 30 of Reviews in Mineralogy introduces in understanding the behavior of magmatic volatiles and their influence on a wide variety of geological phenomena; in doing this it also becomes apparent that there remain many questions outstanding. The range of topics we have tried to cover is broad, going from atomisticscale aspects of volatile solubility mechanisms and attendant effects on melt physical properties, to the chemistry of volcanic gases and the concentrations of volatiles in magmas, to the global geochemical cycles of volatiles. The reader should quickly see that much progress has been made since Bowen voiced his concerns about Maxwell demons, but like much scientific progress, answers to old questions have prompted even greater numbers of new questions. The Voltiles in Magmas course was organized and transpired at the Napa Valley Sheraton Hotel in California, December 2-4, 1994, just prior to the Fall Meetings of the American Geophysical Union in San Francisco.

Dynamic Magma Evolution

Dynamic Magma Evolution PDF

Author: Francesco Vetere

Publisher: John Wiley & Sons

Published: 2021-01-07

Total Pages: 224

ISBN-13: 1119521130

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Explores the complex physico-chemical processes involved in active volcanism and dynamic magmatism Understanding the magmatic processes responsible for the chemical and textural signatures of volcanic products and igneous rocks is crucial for monitoring, forecasting, and mitigating the impacts of volcanic activity. Dynamic Magma Evolution is a compilation of recent geochemical, petrological, physical, and thermodynamic studies. It combines field research, experimental results, theoretical approaches, unconventional and novel techniques, and computational modeling to present the latest developments in the field. Volume highlights include: Crystallization and degassing processes in magmatic environments Bubble and mineral nucleation and growth induced by cooling and decompression Kinetic processes during magma ascent to the surface Magma mixing, mingling, and recharge dynamics Geo-speedometer measurement of volcanic events Changes in magma rheology induced by mineral and volatile content The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.

Tracking the Evolution of Magmatic Volatiles from the Mantle to the Atmosphere Using Integrative Geochemical and Geophysical Methods

Tracking the Evolution of Magmatic Volatiles from the Mantle to the Atmosphere Using Integrative Geochemical and Geophysical Methods PDF

Author: Nathalie Vigouroux-Caillibot

Publisher:

Published: 2011

Total Pages: 508

ISBN-13:

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This thesis characterizes the transfer of magmatic volatiles through the mantle and the crust to the atmosphere through the integration of melt inclusion data for pre-eruptive volatile contents with surface measurements of volcanic degassing (recorded in micro-gravity changes and volcanic fumarole and plume gas compositions) at two contrasting volcanoes: Sierra Negra, Galápagos Islands and Kawah Ijen, Indonesia. In particular, it explores the process of fluid transfer in the mantle, the partitioning of volatile elements during mantle melting and degassing of the magma through the crust, and the effect of near-surface (e.g., interactions with groundwater and hydrothermal fluids), and surface processes (e.g., cooling and mixing with air) on the gas species. The effects of differences in initial volatile content and internal volcano structure on the types of eruptions and emissions recorded at each volcano are also discussed. The comparison of Sierra Negra and Kawah Ijen volcanoes reveals that differences in style of volcanic activity are primarily a function of magmatic plumbing system as opposed to differences in initial volatile content. In both cases, permeability of the crust and degassing style have exerted a dominant control over the recent style of activity (last century). Recent eruptions at Sierra Negra are not necessarily associated with magma recharge into shallow reservoirs but can be caused by subtle changes in the pressure regime of a magma chamber, a process which is closely associated with degassing and system permeability. Large explosive eruptions at Kawah Ijen are currently impeded by the open system (permeable) flow of magma and gas through the plumbing system. Hydrothermal systems play an important role in controlling the permeability of a system and the composition of the gases measured at the surface. The comparison of theoretically modeled gas compositions with actual measured compositions is an effective approach to studying the influence of hydrothermal systems at open vent volcanoes.

The Transfer of Volatiles Within Interacting Magmas and Its Effect on the Magma Mingling Process

The Transfer of Volatiles Within Interacting Magmas and Its Effect on the Magma Mingling Process PDF

Author: Matthew Wayman

Publisher:

Published: 2011

Total Pages: 38

ISBN-13:

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The input of volatile-charged mafic magma into chemically evolved felsic magma reservoirs in the shallow crust leads to the exchange of heat and chemical components that may serve as the trigger for subsequent volcanic eruption. The exchange of volatiles, which occurs via diffusion and potentially through fluid movement, is particularly important to this process. In order to simulate the magma mingling process and the role of volatiles within this process, we have conducted a series of hydrothermal experiments involving a hydrous basaltic-andesite glass containing trace olivine (prepared from a natural sample of Augustine volcano in Alaska's Aleutian Arc) with crystal-deficient, anhydrous or hydrous Los Posos rhyolite glass (also natural) at 100 MPa. Some experiments were conducted under fluid-absent conditions while others involved O-H-Cl±S-bearing fluids. Temperature was varied during these experiments, with most beginning at 1100°C. Temperature was subsequently reduced to 800°C in several steps, where it remained until an isobaric quench. The run durations ranged from 25 to 125 hours. The experimental products exhibit interesting textural and chemical features. The rhyolitic run product glass, whether hydrous or anhydrous initially, exhibits minimal crystallization throughout the experiments, whereas the starting basaltic-andesite glass shows significant crystallization of iron and titanium oxides, plagioclase, and pyroxene. The exchange of Cl between the two melts was significant for fluid-present and fluid-absent conditions, and the concentration of Cl in the more felsic melt was strongly controlled by well established Cl solubility relationships involving the cations Ca, Al, Na, and Mg and the presence or absence of S.

Magma Dynamics and Evolution in Continental Arcs

Magma Dynamics and Evolution in Continental Arcs PDF

Author: Stephanie B. Grocke

Publisher:

Published: 2014

Total Pages: 303

ISBN-13:

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Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop overthickened continental crust (80 km thick), provides insights into large volume silicic magma reservoirs and how they evolve prior to their potentially catastrophic explosive eruption on the Earth's surface. A focused case study of the Cerro Guacha Caldera Complex (CGCC), a nested volcanic system in the Altiplano-Puna Volcanic Complex of SW Bolivia, puts constraints on the progressive stages of development of the magmatic underpinnings of the caldera complex. Whole rock data, in conjunction with matrix glass, mineral compositions and melt inclusions, are used to infer processes that gave rise to the formation of the Guacha II Caldera, the younger of two main collapse features, formed from the supereruption of the Tara Ignimbrite (800 km3 DRE) at 3.49 ± 0.01 Ma. The eruptive history of the Guacha II Caldera from pre-caldera to post-caldera is fully represented, allowing magma dynamics associated with a complete caldera cycle, from pre-climactic (catastrophic caldera-forming) magma accumulation through to post-climactic effusions that are part of the resurgent history of the caldera, to be examined. Analysis of the high-K, calcalkaline suite of andesite to high Si-rhyolite Tara pyroclastic deposits provides insights into the storage conditions and magma dynamics leading up to a supervolcanic eruption. The Tara eruptive products define a liquid line of descent from the basal andesite lava (62 wt % SiO2) to the high-silica rhyolite post-collapse Chajnantor Dome lava (78 wt.% SiO2), with major and trace element trends consistent with fractionation of quartz, plagioclase, orthopyroxene, hornblende, sanidine, biotite, and Fe-Ti oxides. Isotope ratios span a significant range in 87Sr/86Sr (0.709 to 0.713) and a relatively narrow range in 143Nd/144Nd (0.512179 to 0.512297) and [delta]18O[subscript (qtz)] (+8.68 to +8.43[per mil]). These data require AFC processes to explain both the isotope and trace element compositions in the Tara magmas. Geothermobarometry reveals pre-eruptive temperatures (~800 - 950 °C), pressures (~200 MPa), and H2O contents (~5 wt%) that suggest storage of a large-volume rhyodacite magma reservoir between 5 and 9 km depth in the upper crust. Analyses of quartz-hosted melt inclusions from pumices in the climactic plinian and ignimbrite phase of eruption reveal that pre-eruptive H2O contents in the plinian pumice overlap with those in the ignimbrite pumice (2.2 to 6.0 and 2.1 to 5.4 wt.% H2O, respectively). The ignimbrite magma, however, contains higher CO2 (630 versus

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