Mullite-corundum-spinel-cordierite-plagioclase xenoliths in the Skaergaard Marginal Border Group: multi-stage interaction between metasediments and basaltic magma

Markl, Gregor

doi:10.1007/s00410-004-0644-5

Cited by 21 publications

(10 citation statements)

References 54 publications

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“…Mullite is a scarce mineral in nature; however, it is common in artificial products such as porcelain, refractories with high alumina content, etc. Some works reported mullite crystallization associated to the calcination of clays by spontaneous coal combustion (Alastuey et al, 1993) and with pyrometamorphic environments (Markl, 2005; . Backscattered electron images (FESEM of sample CHECA-3B: a) sample fired at 1200°C showing the texture characteristics of an advanced vitrification process, b) sample fired at 1200°C that displays fractured quartz with more developed reaction edges and immersed in a vitreous phase with nanometer mullite, c) sample fired at 1300°C that shows the texture characteristics of an intense vitrification process, d) nanometer sized acicular crystals of mullite with random orientation immersed in a vitreous matrix.…”

Section: Mineral Transformationsmentioning

confidence: 99%

“…Mullite crystallizes in these samples from 1000°C, forming acicular crystals distributed with variable orientations in the fired samples and whose thickness increases with temperature up to 40-70 nm. Analyses of natural mullite using electron microprobe have been reported by Markl (2005) and Sokol et al (1998). Markl (2005) gives the composition of mullite formed in xenolithes in contact with pyrometamorphic interaction ( Table 2, Fig.…”

Section: Genesis and Composition Of The Vitreous Phase And Mullitementioning

confidence: 99%

“…Analyses of natural mullite using electron microprobe have been reported by Markl (2005) and Sokol et al (1998). Markl (2005) gives the composition of mullite formed in xenolithes in contact with pyrometamorphic interaction ( Table 2, Fig. 8b) and Sokol et al (1998) describe mullites formed in pyrometamorphic rocks associated with naturally burned coal (Table 2.…”

Section: Genesis and Composition Of The Vitreous Phase And Mullitementioning

confidence: 99%

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Mineral and textural transformations in aluminium-rich clays during ceramic firing

Laita

Bauluz

2018

Applied Clay Science

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The aim of this study has been to analyse the mineralogical and textural transformations of a set of aluminiumrich shales of interest for refractory and ceramic uses, fired from 800°C to 1300°C. To that end, raw and fired samples were analysed by X-ray diffraction, transmitted light microscopy, field emission scanning electron microscopy, and transmission electron microscopy. Raw samples comprise variable proportions of illite, pyrophyllite, orthoclase, quartz, kaolinite, mixed-layer I-Sm, and organic matter. At temperatures below 800°C, kaolinite, mixed-layer I-Sm, and organic matter are destabilized, indicating that they are the least stable phases in the firing process. Illite, pyrophyllite, and orthoclase remain until 1000°C and show a broader stability field during firing than in natural environments. Quartz persists throughout the entire firing process, although it is partly replaced by vitreous phase. Hematite crystallizes at 900°C. Vitrification begins at 1000°C, marking the first significant textural change. From 1000°C mullite starts to crystallize from the Si-and Al-rich vitreous phase. The mullite composition is not stoichiometric and probably as temperature increases Si is partially replaced by Al, Fe and Ti in the structure. Nevertheless, with the increase of the firing temperature, the mullite composition is closer to the theoretical composition and also to that of natural mullites. Furthermore its crystal thickness increases with temperature up to 70 nm. The samples analysed in this study were taken from a shale outcrop

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Section: Mineral Transformationsmentioning

confidence: 99%

Section: Genesis and Composition Of The Vitreous Phase And Mullitementioning

confidence: 99%

Section: Genesis and Composition Of The Vitreous Phase And Mullitementioning

confidence: 99%

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Mineral and textural transformations in aluminium-rich clays during ceramic firing

Laita

Bauluz

2018

Applied Clay Science

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“…These materials could thus be used in the manufacture of stoneware and ceramic floor, as well as in refractory ceramics. Some of these new phases are also reported in natural processes such as metamorphism [14,23,24] and igneous processes [25][26][27]. For this reason, determining the chemical and textural characteristics of all the new phases may shed light on the characteristics of the spontaneous combustion of coal as well as on the differences between this natural process and other natural or ceramic processes.…”

Section: Introductionmentioning

confidence: 92%

High-Temperature Mineral Phases Generated in Natural Clinkers by Spontaneous Combustion of Coal

2019

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The aim of this study is to analyze natural clinkers (= calcined clays by coal combustion) from a lower Cretaceous coal outcrop in Ariño (Teruel, NE Spain) in order to describe mineral and textural transformations produced during the spontaneous combustion of coal. To achieve this aim, samples were analyzed using X-ray diffraction and optical and electron microscopy. Spontaneous combustion resulted in the melting of the surrounding clays, with the generation of an Al–Si-rich vitreous phase. Subsequently, high-temperature phases crystallized from this vitreous phase. These new minerals are interesting due to their similarity with those formed during ceramic processes, used in the manufacture of stoneware and ceramic tiles, as well as in refractory ceramics, and with natural events such as metamorphic and igneous processes. The studied natural clinkers are composed of vitreous phase mullite, hematite, hercynite, cristobalite, quartz, pyroxenes, cordierite, gypsum, pyrite, and calcium oxides. A trend from hematite to hercynite composition indicates compositional variations at sample scale, which evidence d-spacing differences in hercynite and may be related to the Al and Fe content in hercynite depending on its texture. The mullite shows higher Si/Al ratio (1.21) than the theoretical composition (0.35), indicating that this mullite is more Si-rich. Three pyroxene-type compositions (diopside-type, ferrosilite-type, and a Ca–Al-rich pyroxene) were found. Both the mullite and the pyroxenes are nonstoichiometric.

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“…[49] Total fusion of the xenoliths forming an immiscible liquid that subsequently quenched to produce the characteristic mineral zonation has been suggested for xenoliths at Voisey's Bay [e.g., Ryan, 2000] and also for metapelitic xeno-liths in the Skaergaard Intrusion [e.g., Mark, 2005]. However, total fusion is inconsistent with textural evidence presented above which suggests that the xenoliths at Voisey's Bay are characterized by metamorphic textures.…”

Section: Genesis Of Mineral Zoning In Xenolithsmentioning

confidence: 99%

Petrologic evolution of gneissic xenoliths in the Voisey's Bay Intrusion, Labrador, Canada: Mineralogy, reactions, partial melting, and mechanisms of mass transfer

Mariga

Ripley

2006

Geochem Geophys Geosyst

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[1] Nickel-copper-cobalt sulfide ores in the Voisey's Bay Intrusion are closely associated with troctolitic to gabbroic rocks that contain abundant country rock xenoliths. Potential sources of the xenoliths include pelitic paragneiss, enderbitic orthogneiss, and mafic to quartzofeldspathic gneisses that form immediate country rocks to different parts of the intrusion. Regardless of location, all xenoliths have a similar refractory mineral assemblage composed of hercynite, magnetite, Ca-rich plagioclase, and corundum. The refractory mineral assemblage formed via partial melting immediately after xenoliths were engulfed by magma. Rapid thermal equilibration allowed the xenoliths to survive prolonged interaction with magma. Corundum was formed by the incongruent melting of Na-rich plagioclase in pelitic and quartzofeldspathic gneisses. Corundum and Ca-rich plagioclase assemblages are aluminous; their origin involved either multistage melting of protoliths where the production of a granitic minimum melt was followed by the liberation of a more silica-rich and Al-poor melt or one-stage disequilibrium melting. Density differences between the xenoliths, restite assemblages, and enclosing mafic magma facilitated the separation of partial melt from restite. No evidence for the melts in the form of channels or interstitial glass is observed in the restite. Flow of mafic magma in the conduit system is thought to have dispersed the Si-and alkali-rich melts derived from the xenoliths. The only record of the xenolith-derived melts is in the form of concentric rims of plagioclase and biotite which crystallized from a hybrid melt in boundary layers around most xenoliths. Hercynite in the restitic assemblage was produced either by partial melting involving Fe-and Mg-bearing minerals such as garnet and pyroxene or by replacement of corundum. FeO and MgO that were excluded from the boundary layer diffused inward and reacted with corundum to form hercynite. The thickness of the hercynite bands suggests formation times between 3,000 and 23,000 years. Where the insulating rims of plagioclase and biotite were not present, diffusion of FeO and MgO from the surrounding crystal mush continued, resulting in near complete conversion of corundum to hercynite. The highly refractory mineral assemblages which characterize xenoliths present in the Voisey's Bay Intrusion provide evidence for a complex history of magma-country rock interaction. The transfer of xenomelts and sulfur to flowing magma may have been essential for the formation of the magmatic sulfide ores.

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Mullite-corundum-spinel-cordierite-plagioclase xenoliths in the Skaergaard Marginal Border Group: multi-stage interaction between metasediments and basaltic magma

Cited by 21 publications

References 54 publications

Mineral and textural transformations in aluminium-rich clays during ceramic firing

Mineral and textural transformations in aluminium-rich clays during ceramic firing

High-Temperature Mineral Phases Generated in Natural Clinkers by Spontaneous Combustion of Coal

Petrologic evolution of gneissic xenoliths in the Voisey's Bay Intrusion, Labrador, Canada: Mineralogy, reactions, partial melting, and mechanisms of mass transfer

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