نتایج جستجو برای: acidic magma
تعداد نتایج: 41771 فیلتر نتایج به سال:
Major element compositions of glass inclusions in olivine and plagioclase phenocrysts from representative Mariana arc lavas show that mafic Mariana arc liquids are tholeiitic and not high-alumina, implying that the high-alumina characteristic of these lavas reflects accumulation of plagioclase. Glass inclusions also show the common occurrence of felsic melts previously unrecognized among Marian...
These notes complement the lectures and aim to give you practical experience in working with Galois groups in Magma. They are aimed at people for whom working with Magma is something of a struggle. I myself am still in this category, although perhaps starting to leave it, having written these notes . . . . Given the aims, the exercises corresponding to the first two lectures are intended to be ...
Previous estimates of crustal storage time of magmas at Kilauea Volcano, Hawaii, range from a few years to a few thousand years, leading to considerable uncertainty in the time scales of processes of magmatic storage and differentiation. We present a new approach for determining minimum magma residence times which involves dating phenocrysts in a magma using 226Ra^230Th disequilibria, and apply...
[1] Multiple mechanisms have been suggested to explain seaward motion of the south flank of Kīlauea Volcano, Hawai‘i. The consistency of flank motion during both waxing and waning magmatic activity at Kīlauea suggests that a continuously acting force, like gravity body force, plays a substantial role. Using finite element models, we test whether gravity is the principal driver of long-term moti...
The rates of passive degassing from volcanoes are investigated by modelling the convective overturn of dense degassed and less dense gas-rich magmas in a vertical conduit linking a shallow degassing zone with a deep magma chamber. Laboratory experiments are used to constrain our theoretical model of the overturn rate and to elaborate on the model of this process presented by Kazahaya et al. (19...
Crustal extension at mature continental rifts and oceanic ridges occurs by a combination of normal faulting and magma injection, which interact to create rift morphology. Quantifying the relative roles of faulting and melt intrusion in accommodating extension at magmatic rifts remains difficult and requires studies at sufficient spatial and temporal scales to resolve the interaction between the...
In monitoring active volcanoes, the magma overpressure is one of the key parameters used in forecasting volcanic eruptions. This parameter can be inferred from the ground displacements measured on the Earth’s surface by applying inversion techniques. However, in most studies, the huge amount of information about the behavior of the volcano contained in the temporal evolution of the deformation ...
Introduction: Volatile content of a planetary magma ocean has significant effects on the process of magma ocean solidification, on formation of an initial planetary atmosphere, and on subsequent mantle composition [1-5]. The heterogeneous partitioning of volatile phases during accretion and differentiation of the Earth and Mars can account for current volatile budgets without the need to invoke...
Geological and physical observations and constraints are applied to the development of a model of the ascent and emplacement of basaltic magma on the earth and moon. Mathematical models of the nature and motion of gas/liquid mixtures are developed and show that gas exsolution from terrestrial and lunar magmas commonly only occurs at shallow depths (less than 2 km); thus the ascent of bubble-fre...
Volcano monitoring uses knowledge of volcanic processes and extensive data gathering to analyze areas of volcanic activity. The main goal is to learn the nature of the volcano, the magmatic processes occurring, and the likelihood of a future eruption. Volcano monitoring centers around three aspects of volcanic processes: ground deformation, seismic activity, and gas emissions. These techniques ...
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