Compositional Convection In Viscous Melts
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Geochemistry 3 Volume 5 Geophysics Geosystems
melts generated in off-axis plume-ridge systems. Significant differences in flow between systems in which viscosity is only a function of temperature (i.e., h(T)) and systems in which viscosity is a function of temperature and water content (i.e., h(T,F)) lead to differences in the geochemical signatures of the resulting melts. Comparison of
K2° - NASA
(a) Glass Melts Using 'oxides and carbonates several batches were calculated to make glasses in the vicinity of the following composition: (in weight per cent) Si02 72 A1203 13 Fe304 5.8 CaO 1.9 Na20 1.5 2.3 TiOZ 0.7 K2° MnO 0.1 First melting attempts were made in platinum crucibles at 15OOOC. ' While glasses were obtained, they
Relations between the anionic structure and viscosity of
delineated. These compositional ranges (0 20, -20-50, and >50 moleVo metal oxide) coin-cide with compositional ranges defined by thermal expansivity data and data on the activa-tion energy of viscous flow. Melts on the join NaAlOr-SiO, have a three-dimensional array of SiOo and AlOo tetra-hedra.
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Stirring and structure in mantle starting plumes
plumes, stirring may contribute to compositional variance in hotspot basalts. Griffiths [10-12] demonstrated that when a hot buoyant volume of fluid is placed in very viscous fluid the hot material will form a rising spherical vortex which continuously heats and entrains the adjacent fluid as it ascends.
Fluid dynamics of the solid Earth (L16)
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Non-hotspot volcano chains from small-scale sublithospheric
crustal melts are generated at lower temperatures than mantle melts, and produce light low-viscous rapidly ascending magmas. Drip-like down-sagging of the lithospheric mantle and metamorphic lower crustal material inside the plume head may contami-nate the latter and also alter the geochemical signature of related magmas.
Distributed Compositional and Temperature Nature of Melts in
100 micron in size 1000 times as viscous as water would retain its identity for up to 3 hours. If it is taken into account that discrete mineral particles have to melt, intermix with other fluxes, be reduced, and that silicate polymers also exist within slag melts, it becomes apparent that fluid elements of slags may take a
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Keywords: Earth s mantle, convection currents, lithosphere, strength, plate tectonics, tectonic forces, stress in the lithosphere, deformation, earthquakes Contents 1. Introduction 2. The Earth s Interior Thermal and Compositional Structure 2.1. Internal Heat 2.2. Geospheres 3. The Mantle Engine 3.1. Short-Term Mantle Properties 3.2.
Transport properties of silicate melts
Silicate melts have also been instrumental in shaping other rocky planets and the Moon [Shearer et al., 2006; Smrekar et al., 2010; Elkins-Tanton, 2012]. Silicate melts have been a key agent in transporting matter and heat in the Earth s interior at all stages of its history.
The role of viscosity contrast on plume structure in
Apr 29, 2016 In previous convection experiments driven by thermal buoyancy for example (Manga and Weeraratne, 1999; Lithgow-Bertelloni et al., 2001), the buoyancy ﬂux and ﬂuid viscosity were coupled as the ﬂuids had a temperature-dependent viscosity. The use of compositional buoyancy to drive the convection provides us the opportunity to study
Earth and Planetary Science Letters
layer thickness H, the most viscous magmas should be expected to be among the most heterogeneous. Moreover, although thermal and compositional convection clearly occurs in magma reservoirs (Grout, 1918) and can act as an homogenizer (e.g., Whitney and Stormer, 1985; Oldenburget al.,1989; Lindsayet al., 2001; Christiansen, 2005),
Nonfractional crystallization of a terrestrial magma ocean
However, almost independently of this value, convection occurs even in the highly viscous quasi- solid part of the magma ocean and it is strong enough to prevent differentiation in deep regions. A kind of compositional convection occurs due to the layered differentiation, although it is weaker than the thermal convection.
Thermochemical convection and helium concentrations in mantle
compositional heterogeneous region may extend up to 1000 km above the CMB. Another major unresolved issue by purely ther-mal convection models is the well known geo-chemical di¡erence between depleted mid-ocean ridge basalts (MORB) and enriched ocean island basalts (OIB) (see  and references therein).
Double-Diffusive Convection Due to Crystallization in Magmas
the physical and chemical properties of silicate melts are such that we consider double-diffusive convection certain to occur. Recent detailed studies of volcanic rocks have also demonstrated that many magma chambers contain stable compositional gradients but unstable temperature
Chapter 11: Diversification of Magmas
Compositional convection → evolved magmas from boundary layer to cap (or mix into interior) Figure 11-12 Formation of boundary layers along the walls and top of a magma chamber. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall BOUNDARY LAYER CRYSTALLIZATION Liquid immiscibility in the Fo-SiO2 system
segregation Magma mixing enhanced by bubble
(ii) Vigorous convection in a magma reservoir, in turn, forms through strong T contrasts from transient mac replenishment and may entrain, stretch and fold portions of mac 25 magma by viscous coupling (Huppert et al., 1983, 1984; Snyder and Tait, 1996). (iii) Double-di usive convection depends on heat and molecular di usivity, when both of
Assessing the Role of Compaction in the Formation of
during compositional convection in the mush (Sparks et al., 1985; Tait & Jaupart, 1992). The second group of models is perhaps of more gen-eral relevance to igneous systems across the compos-itional range and is predicated on the expulsion of evolved interstitial melt from the mush. Be´dard (2015) suggested that melt can be expelled from mush
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Earth and Planetary Science
melt in the cumulate is discussed later. Viscous ﬂow in the cumu-late layer occurs in response to the unstable compositional and/or thermal stratiﬁcation. In turn, the viscous ﬂow causes composi-tional mixing and convective heat transport. Rather than modeling a particular MO scenario, the goal of the current study is to in-
MECHANISMS FOR THE CRYSTALLIZATION OF ZBLAN Edwin C. Ethridge
Relatively high growth and nucleation rates have been reported in lithium di-silicate melts extruded at 540C where steady state nucleation and growth are practically zero for non-stressed samples8. Even though under most conditions glasses exhibit Newtonian viscous flow, non-Newtonian viscous flow
On the Origin of Crystal-poor Rhyolites: Extracted from
tain interstitial rhyolitic melt. Second, convection ceases once a rigid crystal framework is attained, which is thought to occur at around 50 55% crystals (Rigid Percolation Threshold, RPT; Vigneresse et al., 1996). The onset of yield strength in crystal melt suspensions, thereby retarding convection, may even occur at lower
Chapter 5 - Thermodynamic and Transport Properties of
EA Activation energy for viscous ﬂow (J/mol) V A Activation volume for viscous ﬂow (m 3/mol) h r Relative viscosity, ratio of mixture viscosity to melt viscosity f Volume fraction dispersed phase (solid or vapor) k R Radiative (photon) conductivity (J/m K s) k Thermal conductivity (J/m K s) k Thermal diffusivity, k/rc p (m2/s)
1. INTRODUCTION TO THE EARTH - gfd-dennou.org
compositional convection, due to compositional differences between melt and solid laminar entrainment by rising hot plumes separation of small amounts of melt from the interstitial crystal mush by compaction large (huge?) variation of physical (and chemical) properties between magmas density of melt originating from solid determines subsequent
Heat sources and melting in subduction zones
viscous heating in a narrow zone at the slab-wedge in- terface. However, assuming a reasonable rheology, the mantle wedge will undergo viscous deformation and in- duce a large-scale convection [e.g., Yuen et al., 1978], where the flow plays an essential role in transporting heat. The flow pattern and thermal structure in the man-
AGU Planet Earth Committee Report Part II Interior and Crust
and compositional variations. Laboratory measurements of th e densit silicat melts at very high pressures in shock wave appara tus sugges t tha mel produced below 200-300 k depth may b e denser than th solid matrix. Thi s strongly implie that the evolu tion of a planetary body depends on its size, which greatly affects pressures at depth.
PHYSICS OF MAGMATIC PROCESSES - Magma Dynamics
sists of three main parts: momentum transport (e.g., viscous flow in conduits and diapirs, segregation and flow of melt in crystal mushes), energy transport (heat conduction, buoyancy convection, viscous dissipa tion) and mass transfer (diffusion and advection-aided diffusion, infiltra
Thermal Structure due to Solid-State Flow in the Mantle Wedge
compositional dependence (e.g., discussion in [Johnson and Plank , 1999]). Thus, relatively small changes in thermal models, which make them consistent with PT constraints from the lower crust and uppermost mantle, might also lead to a resolution of the apparent paradox in which geochemistry suggests partial melting of subducted sediment and
Melt densities in the Na2O-FeO-Fe2O3-SiO2 system and the
compositional variations can provide tests for the evaluation of the style and magnitude of convection in these chambers (e.g. HUPPERT and SPARKS, 1980; CAMPBELL and TURNER, 1986). Thirdly, the density of the melt is an input parameter in deriving the melt-buffer rod interface reflection coefficient
HLW Vitrification Research and Development
Conventional JHCMs rely on natural convection in a viscous melt Melt rate is limited by heat and mass transport at the cold cap VSL developed active melt pool mixing using bubbler arrays Provides drastic increases in melt rates Up to 5X Incorporated into WTP HLW and LAW melters Successfully retro-fitted into DWPF
EXPERIMENTAL CONSTRAINTS ON COMPOSITION OF LUNAR MAGMA OCEAN
floated in the melts of all the compositions in the present study at 0.5 GPa although MELTS predicts that the glass of CI4 has a smaller density than anorthite. This is the first that floatation of anorthite in silicate melt with a plausible compositional range of LMO that can coexist with anorthite is experimentally proved.
Microcrysts RecordTransient Convection at Piton de la
Blake, 1998). For any viscous liquid, including magmas, buoyancy forces maycause instabilities if the denserliquids lie above the less dense ones. Because magmas are gener-ally heated from below and crystallize from above, density inversion is prone to be sustained in most magmatic sys-tems, and may lead to convection (e.g. Jaupart & Parsons
Simulations of convection with crystallization in the system
A model has been developed and applied to study the origin of compositional and phase heterogeneity in magma bodies undergoing simultaneous convection and phase change. The simulator is applied to binary-component solidification of an initially superheated and homogeneous batch of magma. The model accounts for solidified, mushy (two- or
2 First-principles study of FeO2Hx solid and melt system at
43 product of P phase to cause ULVZs, the dense and nearly inviscid melts must be 44 dynamically stable and confined within the ULVZs, which requires that the mantle is 45 highly viscous and/or convects vigorously. As P phase is an important high-pressure
COMPOSITIONAL ZONING AND ITS IMPLICATION IN A TOROIDAL
key words: compositional zoning, magmatic fabrics, diapir 1. Introduction The origin of compositional zoning in granite plutons is an important issue among granite petrologists. Several mechanisms have been proposed to account for chemical heterogeneity in a magma body formed during the segregation, ascent and emplacement of granite melts.
Natural Convection, Solute Trapping, and Channel Formation
The two styles of compositional convection seen in the experiments can be understood in terms of a general theory of convection in mushy layers,13 which also predicts a criterion for the onset of internally driven convection. Rather than calculating the microstructural morphology of the solid phase,
4 Outcroppings Research in the department 2015-2016
right time, for viscous silicic melts, like granites, to segregate from crystal-rich magmas 33. Cin-Ty s group also developed new ways to determine the critical melt porosity for crystal-liquid segregation during crystallization of a magma and during partial melting of metamorphic rocks34, 35. Finally,
Magma mixing enhanced by bubble segregation
(ii) Vigorous convection in a magma reservoir, in turn, forms through strong T contrasts from transient maﬁc replenishment and may entrain, stretch and fold portions of maﬁc 25 magma by viscous coupling (Huppert et al., 1983, 1984; Snyder and Tait, 1996). (iii) Double-di usive convection depends on heat and molecular di usivity, when both of
Internal circulation in a buoyant two-fluid Newtonian sphere
tO plutons initially composed of two distinct melts [1,2]. This association is often observed in the form of mechanical mingling and chemical mixing of the two magmas in zoned plutons or as mafic enclaves in granitoids (e.g. [3,4]). The most com- monly described pattern of compositional zoning