Results 211 to 220 of about 23,662 (266)
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Making magma chambers from mush
Science, 2017Volcanology Shallow magma chambers either erupt as volcanoes or solidify as intrusive magma bodies. These magma bodies are traditionally considered to be long-lived and dominated by melt. Cashman et al. review the evidence that shallow magma chambers are actually assembled quickly from much larger, crystal-rich transcrustal magmatic systems.
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Dynamics of magma withdrawal from stratified magma chambers
Geology, 1986The time history of magma withdrawal through a central vent from a flat-roofed chamber strongly stratified in density and viscosity has been numerically modeled. Important parameters include the geometry of the reservoir; the initial vertical compositional profile; the ratio of viscous, inertial, and gravitational forces; and the basal normal stress ...
Frank J. Spera +3 more
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Mid‐ocean ridge magma chambers
Journal of Geophysical Research: Solid Earth, 1992Geophysical evidence precludes the existence of a large, mainly molten magma chamber beneath portions of the East Pacific Rise (EPR). A reasonable model, consistent with these data, involves a thin (tens to hundreds of meters high), narrow (<1–2 km wide) melt lens overlying a zone of crystal mush that is in turn surrounded by a transition zone of ...
John M. Sinton, Robert S. Detrick
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Vibro-agitation of chambered magma
Journal of Volcanology and Geothermal Research, 2007Abstract We present the results of a novel set of calculations into the effect of in situ pressure reduction of a crystal-rich, basaltic magma layer by propagating seismic (P) waves. Three stages in the process are identified. Critically, an instability can arise such that a low pressure melt layer develops close to the floor in initially densely ...
M. Davis, M.A. Koenders, N. Petford
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The Beginning: Mafic Magmas Invading Felsic Magma Chambers
2021The initial stages of magma interaction, i.e. the moment at which the two magmas come into contact, is a crucial point since the fate of magma mixing and its development in space and time largely depend on the outcome of this first encounter. In this chapter we discuss the possible fluid dynamic and thermodynamic processes developing during the ...
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Magma mixing and convective compositional layering within the Vesuvius magma chamber
Bulletin of Volcanology, 1991The pumice-fall deposits of the last two Plinian eruptions of Vesuvius-a.d. 79 “Pompei” and 3700 b.p. “Avellino”-show a marked vertical compositional variation from white phonolite at the base to grey tephritic phonolite at the top. In both Avellino and Pompei sequences a compositional gap separates white from grey pumice.
CIVETTA L, GALATI R, SANTACROCE, ROBERTO
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Properties of Carbonatite Magma and Processes in Carbonatite Magma Chambers
The Journal of Geology, 1983The physical and thermal properties of carbonatite magmas are estimated by analogy with alkali carbonate melts, which are ionic liquids, composed of discrete, unpolymerized ions. Carbonatite magmas are estimated to have low viscosity (on the order of 5 × 10-2 poise), low heat of fusion (175 J/gm), and large thermal diffusivity (4 × 10-3 J/cm-sec-K ...
Allan H. Treiman, Andrew Schedl
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Evaluating volumes for magma chambers and magma withdrawn for caldera collapse
Earth and Planetary Science Letters, 2014Article history: We develop an analytical model to infer the total volume of a magma chamber associated with caldera collapse and the critical volume of magma that must be withdrawn to induce caldera collapse. The diameter of caldera border fault, depth to the magma chamber, and volumes of magma erupted before the onset of collapse and of entire ...
Geshi N, Ruch J, ACOCELLA, Valerio
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Convection and mixing in magma chambers
Earth-Science Reviews, 1986Abstract This paper reviews advances made during the last seven years in the application of fluid dynamics to problems of igneous petrology, with emphasis on the laboratory work with which the authors have been particularly involved. Attention is focused on processes in magma chambers which produce diversity in igneous rocks, such as fractional ...
J.S. Turner, I.H. Campbell
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Magma Emplacement and Accumulation: From Sills to Magma Chambers
2021The previous chapter has discussed the rise of magma throughout the crust. This fourth chapter focuses on the arrest, emplacement and accumulation of magma. These are indeed primary and widespread processes at volcanoes, as most of the rising magma remains stalled in the crust, with only a fraction being erupted (approximately one tenth; e.g., Shaw ...
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