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Showing 1 to 20 of 20 for “"Magma ascent"”.
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Dynamics of ash eruptions at Vesuvius
… Volcanic ash holds information about magma dynamics within the volcanic conduit, where fragmentation occurs and eruption style is decided. Results of our investigations have been interpreted in terms of fragmentation processes, transport and dispositional mechanisms, dynamics of magma …
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The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa
… phase and an immiscible carbonate liquid during magma ascent: (c) large rounded olivines (megacrysts) up to 40 mm across. Individuals are chemically homogeneous, but megacrysts from the same pipe collectively define a trend of decreasing Mg with Ni (F092, 0.36% Ni to F075, 0.17% Ni). The most …
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Petrogenesis of kimberlites from South Africa and lamproites from Western Australia and North America
… are not due to crustal contamination during magma ascent, rather they are source and extraction phenomena. The mantle source regions of these rocks were ancient (~ 1.0 to 2.5 Ga) and variably trace element enriched. Preservation of such regions within the mantle is most probable in the …
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Transitions between effusive and explosive activity at Merapi volcano, Indonesia: a volcanological and petrological study of the 2006 and 2010 eruptions.
… crystallisation occurs throughout the crust. Magmatic temperatures are estimated to be ~920–1020 °C. Maximum H2O contents reach 3.94 wt.% in 2010 melt inclusions and up to 3.73 wt.% in those from 2006. CO2 concentrations are < 200 ppm, although they may reach up to 695 ppm in some melt …
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Geochemical and petrological investigation into the magmatic system at Soufrière Hills Volcano, Montserrat.
… Hills Volcano, Montserrat exhibit evidence for magma mingling, related to the intrusion of mafic magma at depth. The processes of mass transfer and flux of material involved in the interaction between mafic and silicic magmas are crucial for understanding eruption dynamics. Detailed textural, …
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Arc magmatism at different crustal levels, North Cascades, WA
The mechanisms of magma ascent and emplacement inferred from study of intrusive complexes have long been the subject of intense debate. Current models favor incremental construction, but much of this work has been focused on a single crustal level. However, the study of magmatism throughout the …
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Geophysical and geochemical constraints on submarine volcanic processes
… Axial Seamount eruption in order to evaluate magma ascent and lava flow rates. I show that the variability in ascent rates during the 2011 eruption spans the range previously proposed over the global mid-ocean ridge system. I suggest that the variability in ascent rates relates to lateral dike …
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Timing and emplacement of the Philipsburg batholith, SW Montana, and a comparison of two magnetic fabric techniques
… (AMS) is used extensively to determine magma flow fabrics in both intrusive and extrusive igneous rocks. The anisotropy of anhysteretic remanent magnetization (AARM) allows determination of the anisotropy of ferro/ferrimagnetic minerals in igneous rocks, which have a strong control on …
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GEOCHEMISTRY OF LARGE EXPLOSIVE ERUPTIONS FROM THE MAIN ETHIOPIAN RIFT
… the active tectonics has repeatedly favoured magma ascent along the rift axis resulting in intense volcanic activity characterized by a wide compositional range (from basalts to per-alkaline rhyolites with scarce intermediate products). During the Quaternary, numerous high-magnitude explosive …
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Neon, Helium and Argon isotope systematics of the Hawaiian hotspot
… due to solubility controlled gas loss during magma ascent. However, the preferential He loss suggests that He is more incompatible than Ne and Ar during magmatic processes. In a binary mixing model, the isotopic He and Ne pattern are best explained by a mixture of a MORB-like end-member with a …
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Magma emplacement and deformation in rhyolitic dykes : insight into magmatic outgassing
… distribution of intruded particles and degree of magmatic overpressure required for dyke propagation were governed by the country rock permeability and strength, with pre-existing fractures playing a pivotal governing role. During this stage of dyke evolution significant amounts of exsolved gas …
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Fracture mechanics of volcanic eruptions
… must occur in order to create a pathway for the magma to reach the surface. Time-to-failure forecasting models have been shown to be consistent with seismic acceleration patterns prior to eruptions at volcanoes in subduction zone settings. The aim of this research is to investigate the patterns …
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Monogenetic volcanism in the western Arabian Peninsula: Insights from Late Quaternary eruptions in northern Harrat Rahat, Kingdom of Saudi Arabia
… earth elements (REE) than those with the lowest. Magmatic 3He/4He isotope ratios vary between 9.3 and 11.8 Ra and define the source as plume-like. Trace element modelling and geothermobarometry reveal that partial melting occurred in the asthenospheric mantle (>100 km depth, ~1500 °C, >3 GPa). …
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UNDERSTANDING ERUPTIVE DYNAMICS, PLUME DISPERSAL AND PARTICLE TRANSPORT FOR RISK ASSESSMENT IN PAROXYSMAL MAFIC ERUPTIONS
… estimates of eruptive source parameters, such as magma ascent velocities and magma residence times within the conduit.
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Studies of volatile evolution in magmatic systems using melt inclusions
… evolution associated with active volcanic magmatic systems is of paramount importance because volatiles control and determine the magnitude of an eruption owing to the large change in molar volume that volatile species show depending on their physical state (volatiles dissolved in silicate …
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Dyke-induced earthquakes during the 2014-15 Bárðarbunga-Holuhraun rifting event, Iceland
… in Iceland in 230 years. Over a 13 day period magma propagated laterally from the subglacial Bárðarbunga volcano, Iceland, along a 48 km path before erupting in the Holuhraun lava field on 29 August 2014. A huge variety of seismicity was produced, including over 30,000 volcano-tectonic …
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Tectonic earthquake swarms in the Northern Volcanic Zone, Iceland
… to destructive earthquakes on large faults, magma movement at volcanoes, or the gradual advance of glaciers. Microearthquakes at faults might also signal more exotic behaviour, including due to transient events such as fluid injections or pulses of aseismic fault creep. The study of small …
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Numerical simulations of magma chamber dynamics at Campi Flegrei, and associated seismicity, deformation and gravity changes
… by volcanic monitoring network and shallow magma processes is a crucial headway for the comprehension of volcanic processes and a more realistic evaluation of the associated hazard. This question is very relevant at Campi Flegrei, a volcanic quiescent caldera immediately north-west of Napoli …
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Tassi di risalita vs. degassamento in sistemi vulcanici basici: quantificazione del parametro tempo come fattore primario di controllo dell’esplosività delle eruzioni
Il tasso di risalita del magma rappresenta un parametro fondamentale nella determinazione dell’esplosività di una eruzione. Il suo ruolo deve essere valutato in particolar modo in casi di episodi eruttivi violenti in cui sono coinvolti magmi basici in vulcani a condotto aperto, dove le basse …
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Timescales of magma residence and transport underneath Iceland
… Borgarhraun eruption was fed by mixed primary magmas that ponded near the Moho (approximately 24 km depth). Diffusion chronometry conducted on olivine macrocrysts show that crystal entrainment into the carrier-liquid took place approximately 13 days before eruption with some crystals having …