The viscosity of an iron-bearing melt with composition similar to Unzen andesite was determined experimentally in the high (10 9-10 10.5 Pa s) and low (5-1000 Pa s) viscosity range using a parallel plate viscometer and the falling sphere method, respectively. Falling sphere experiments were carried out in an internally heated argon pressure vessel and …
Try logging in through your library or institution to get access to these tools. Find your institution now ... More like this ; Dynamics and thermodynamics of magma mixing: Insights from a simple exploratory model. Spera, Frank J; Schmidt, Jason S; Bohrson, Wendy A; Brown, Guy A. The American Mineralogist; Washington Vol. 101, Iss. 3, (2016 ...
The mixing of magmas with different compositions is a basic process on Earth (Wilcox, 1999).For plutonic rocks, magma mixing has been widely documented through field evidence such as mafic microgranular enclaves (MMEs) and composite dikes (Didier and Barbarin, 1991, Barbarin, 2005).Geochemically, variations in whole-rock composition are …
Petrogenesis of high Mg# adakitic rocks in intracontinental settings is still a matter of debate. This paper reports major and trace element, whole-rock Sr-Nd isotope, zircon U-Pb and Hf isotope data for a suite of adakitic monzogranite and its mafic microgranular enclaves (MMEs) at Yangba in the northwestern margin of the South China Block. These geochemical data suggest that …
The magma-mixing model explains the reverse zoning and resorption features of phlogopite macrocrysts commonly recognized in calcalkaline lamprophyres elsewhere. Therefore, this mixing mechanism may be globally applicable for the origin of minettes associated with calcalkaline granitic plutonism in post-orogenic settings.
Try logging in through your library or institution to get access to these tools. Find your institution now. Preview Available; ... Degassing and magma mixing during the eruption of Surtsey Volcano (Iceland, 1963-1967): the signatures of a dynamic and discrete rift propagation event.
This chapter is intended to give an overview on the fundamental concepts behind the processes of magma mixing, broadly considering interactions between different magmas.
Here we use a discrete-element numerical model that resolves crystal-scale granular interactions and fluid flow, to simulate the open-system dynamics of a magma mush.
Magmatic enclaves are inclusions of igneous rocks, generally with mafic to intermediate composition, within igneous rocks of more evolved composition that are thought to result from …
Since the first hypothesis, evidences of magma mixing processes have been accumulated in the literature allowing this natural phaenomenon to be defined as fundamental petrological processes playing a role in activating volcanic eruptions and generating compositional variability in igneous systems. Here, we review the key concepts to provide the best understanding of the physical …
Late Triassic Magma Mixing and Fractional Crystallization in the Qingchengzi Orefield, Eastern Liaoning Province: Regional Petrogenetic and Metallogenic Implications
Not until the 1950s was the attention of the geological community drawn to the fact that disparate magmas mix in a special manner: they mingle, the mafic magma being quenched to a …
Irvine, T.N.; Keith, D.W.; Todd, S.G. 1982: Formation of the Stillwater J-M Reef by concurrent fractional crystallization and liquid mixing in a stratified magma body Year Book - Carnegie Institution of Washington 81: 286-294
Access through your institution. Change institution. Buy or subscribe. Subscribe to this journal. ... Snyder, D. & Tait, S. Magma mixing by convective entrainment. Nature 379, 529–531 (1996).
Magma mixing is a widespread, if not universal igneous phenomenon of variable importance. The evidence for magma mixing is found primarily in glassy tephra; the consolidation of lava obscures the evidence. Inclusions of glass in big crystals in tephra, because of their greater range in composition compared to the whole rock and the residual glass, indicate that the big crystals …
We show that magma mixing plays a significant role in the origins of diverse volcanism in the middle Okinawa Trough; more specifically, two of the three types of andesites (types B and C) and one ...
Our results show isothermal undercooling resulting from a change in liquidus temperatures of the interacting magmas due to their changing water content. Specifically, mafic …
The 1883 magma chamber was compositionally and thermally zoned with an upper portion of homogenous rhyodacite at a temperature of 880-890 °C overlying more mafic dacite at 890-913 °C, and andesite at 980-1000 °C. Mafic dacite represents a hybrid magma formed by mixing small amounts of andesite with larger amounts of evolved rhyodacite.
The mechanisms by which felsic and mafic magmas interact and approach a uniform hybrid composition through the processes of mingling and mixing have been studied in a high-level subvolcanic setting in the Spanish Hercynian at Gerena, near Seville. The compositions involved are calc-alkaline and the situation is one of tonalite-quartz diorite synplutonic dykes injected …
At the start of the simulation, new, crystal-free magma is intruded as a dyke at the bottom of the resident mush. The evolution of the subsequent mixing between the resident mush and the new magma by penetrative convection and granular interactions is described and quantified in Fig. 1, and a computer simulation is archived inSupplementary file V1.
Irvine, T. N. (1986) Magma mixing and the origin of the stratiform oxide zones in the Bushveld and Stillwater complexes, in B. Carter (ed), Metallogeny of basic and ultrabasic rocks, Institute of Mining and Metallurgy, ... Western Australia, Institution of Mining and Metallurgy, London, ...
Magma mixing or mingling is a popular hypothesis, generally proposed in terms of blending between a crustal melt and mafic material from the mantle that caused that melting.
The Crustal Magma Storage System of Volcán Quizapu, Chile, and the Effects of Magma Mixing on Magma Diversity
Magma mixing is probably the dominant means of contamina- tion; but assimilation of solid rock is also a proven process (Eichelberger, 1975}. Commonly sufficient record remains in the texture of glassy rocks to permit a sound choice between alternatives. In cases where magma mixing can be inferred, portions of crystals which have grown prior to ...
In situ zircon U-Pb and Hf-isotopic data have been determined for mafic microgranular enclaves and host granitoids from the Early Cretaceous Gudaoling batholith in the Liaodong Peninsula, NE China, in order to constrain the sources and petrogenesis of granites. The zircon U-Pb age of the enclaves (120 ± 1 Ma) is identical to that of the host monzogranite (120 ± 1 Ma), establishing …
About 25–30% of the feldspar phenocrysts contain evidence for magma mixing in the form of (1) partial to severe dissolution–resorption rims, (2) distinct zones of drastically different compositions and (3) overgrowth textures on formerly resorbed crystals. ... If you are a member of an institution with an active account, you may be able to ...
The dioritic suite formed from a mixed magma of an evolved mantle-derived basaltic magma by partial melting of subduction-modified mantle source in response to slab breakoff and a crustal-derived granitic magma at ~ 308 Ma. Before mixing with granitic magmas, basaltic magmas underwent fractional crystallization of olivine to form ferrodiorite.
The mixing time (t mix) is defined as the time required for the intensity of segregation to decay to a certain value. Magma mixing occurs by complex time-dependent flows with numerous flow reversals associated with local unmixing events superimposed on a larger time scale process in which the intensity of segregation decays to zero.
Compositions of melt inclusions are consistent with experimental melts and reflect crystallization of a basaltic parent magma at high P H2O. In contrast, the whole rock …
Here, by using high-pressure mixing experiments and thermal calculations, we show that hybridization during single-intrusive events requires injection of high proportions of …
Mafic microgranular enclaves (MMEs) are common in the monzogranites from the Yangba pluton in the Bikou Terrane of central China. Zircon LA-ICP-MS U-Pb dating yields ages of 208.7 ± 0.7 Ma and 209.3 ± 0.9 Ma for the host monzogranites, and 211.9 ± 0.8 Ma for the MMEs, indicating formation from coeval magmas. The field occurrence and textures including spheroidal shapes, …
The whole-rock composition of the diorite also indicates the evidence for the mixing between basaltic magmas which were fractionated to variable degrees and homogeneous silicic magma. The mixing model proposed from the first direct observations of the IBM middle crust exposed on the Mineoka–Setogawa belt is applied to the genesis of the ...
Our work focuses on the Campi Flegrei caldera, but the results can be extended to other volcanic systems characterized by evidence of mingling …
Magma mixing and the origin of stratiform ore zones in the Bushveld and Stillwater Complexes Other title Mélange de magma et origine des zones à minéralisation stratiforme oxydée dans les complexes du Bushveld et de Stillwater (fr) Author IRVINE, T.N; SHARPE, M.R Carnegie inst ...
We present coupled textural, elemental, and boron isotopic data of tourmaline from the large Zhunuo-Beimulang collision-related porphyry copper deposits (PCDs) located within the western Gangdese, Tibet. Based on morphology and high-resolution mapping, the tourmaline is classified into three paragenetic generations. The first generation of schorlitic Tur-1 occurs in the …