The Habit of Apatite in Synthetic Systems and Igneous Rocks

Wyllie, Peter J.; Cox, K. G.; Biggar, G. M.

doi:10.1093/petrology/3.2.238

Cited by 224 publications

(67 citation statements)

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“…The rare occurrence of amygdaloidal variety of the pyroxenebiotite quartz monzodiorite documented from the borehole in the Skalice quarry indicates a rather shallow (subvolcanic) intrusion for the tìpánovice dyke. The skeletal morphology of ilmenite and zircon lend further support to magma crystallization at high cooling rates, as does the presence of acicular apatite (Wyllie et al 1962).…”

Section: Mode Of Emplacementmentioning

confidence: 78%

Late-orogenic Variscan magmatism: The case of quartz monzodiorite dykes from the Blanice Graben, southern Bohemia

Vrána¹,

Janoušek²

2012

J. Geosci.

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Pyroxenebiotite quartz monzodiorite of the tìpánovice dyke (3 km long and up to 50 m wide), together with additional small occurrences further north, is associated with the Late Variscan Blanice Graben in the Moldanubian Zone of southern Bohemia. The texture is subophitic, fine-to medium-grained, with skeletal crystals of ilmenite and zircon. This, together with rare amygdaloidal texture, indicates a rapid cooling of the melt emplaced at shallow (subvolcanic) crustal levels.

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Section: Mode Of Emplacementmentioning

confidence: 78%

Late-orogenic Variscan magmatism: The case of quartz monzodiorite dykes from the Blanice Graben, southern Bohemia

Vrána¹,

Janoušek²

2012

J. Geosci.

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“…The rheomorphic liquids are only preserved as fresh quenched glasses in those cases where the partial fusion took place on a very small scale, adjacent to or within a dyke, sill or plug (e.g. Wyllie, 1961). In one such instance, Butler (1961) has shown that the fusion was not an isochemical process but involved local metasomatic re-distribution of Na20 and K20.…”

Section: Discussionmentioning

confidence: 99%

Thermal aspects of the origin of Hebridean Tertiary acid magmas. I. An experimental study of partial fusion of Lewisian gneisses and Torridonian sediments

Thompson

1981

Mineral. mag.

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ABSTRACT. Thermal aspects of the conflicting hypotheses that the acid magmas of the British Tertiary Igneous Province were generated by either fractional crystallization of basic magmas or partial fusion of country rocks around basic intrusions are investigated by combining petrological and experimental data. Sparse large xenoliths (up to 12 m 2 outcrops) of Lewisian gneiss occur in the ferrodiorite member of the Marscoite Suite in the Western Redhills Eocene intrusive complex of Skye. Most of the blocks are of granodioritic-tonalitic gneiss which is very similar to the grey gneisses of the northern and southern regions of the mainland Lewisian. One is a two-pyroxene basic granulite, closely resembling in petrography and composition the granulite-facies basic gneisses of the central region of the Scottish mainland Lewisian. During Tertiary thermal metamorphism the xenoliths recrystallized patchily to pyroxene hornfelses and up to 509/oo of melting occurred in any parts of blocks that were rich in alkali feldspar and quartz. Microprobe analyses of intergrown Ca-rich and Ca-poor pyroxenes in a hornfeised ultramafic mica pyroxenite lens within a leucogneiss block give a calculated temperature of 950 ~ for the Tertiary metamorphism. Melting experiments at 1 kb PH2o were carried out on leucocratic and mesocratic Lewisian gneisses (from the xenoliths), Torridonian arkose and shale. Extensive melting of the leucogneiss and arkose, to peraluminous liquids, occurs within a few degrees above their solidus (715 ~ The silicate liquidus of the leucogneiss is at 930 ~ Microprobe analyses of the glass products of melting experiments (mostly of leucogneiss) show that liquid composition trends during progressive melting are consistent with theoretical equilibria in the synthetic system Ab-Or An-Qz-H20. Partial fusion in the Skye Lewisian gneiss xenoliths took place at a water vapour pressure of a few hundred bars, probably under water-undersaturated conditions.

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“…The extremely acicular apatite crystals grew early enough to be enclosed by the sanidine. Their morphology points to very rapid growth (Wyllie et al, 1962), possibly triggered by an early phase of volatile release. Certainly the lack of any hydrous ferromagnesian minerals suggests a relatively anhydrous magma, although the growth of zeolites clearly indicates concentration of hydroxyl ions and water at the latest crystallisation stage.…”

Section: Origin Of the Loudoun Hill Autolithsmentioning

confidence: 99%

Silica-undersaturated trachytic rocks of central Scotland

Upton

Stephenson

Ellam

2007

SJG

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Synopsis The paper presents a review of silica-undersaturated salic intrusions (nenormative trachytes and phonolites) from the Carboniferous-Permian magmatic province in central Scotland. New whole-rock major and trace element analyses, together with Sr and Nd isotopic data, are presented for six intrusions (Bass Rock, North Berwick Law, Traprain Law, Hairy Craig, Fintry and Loudoun Hill) and two syenite autoliths within the Loudoun Hill intrusion. On the basis of the conventional total alkalis vs. silica diagram, all six intrusions are trachytes except for Traprain Law, which is a phonolite. TraprainLaw is the most highly evolved and the most undersaturated in silica. The Loudoun autoliths are the most basic IntroductionThe Carboniferous and Permian igneous rocks of central and southern Scotland are predominantly basaltic and range from transitional to mildly alkaline to highly alkaline (Upton et al., 2004). A major suite of tholeiitic basic intrusions that was emplaced during Stephanian time is an exception. The most primitive members of the various suites range from quartz-hypersthene (q-hy)-to hypersthene (hy)-to nepheline (ne)-normative (Macdonald, 1975;Smedley, 1986). During the past thirty years petrological and geochemical attention has primarily been focussed on these more primitive rocks to the near-exclusion of the more-evolved rocks. More-evolved lavas in the range trachybasalt -trachyandesite -trachyte are restricted to the Tournaisian to mid-Visean sequences and there is a close spatial association between these lavas and intrusions of comparable, and even more-evolved, rock-types ( Figure 1). Hence the evolved intrusions have been assumed to be of the same age as the evolved lavas. Younger magmatism (Late Visean to Permian), however, was, with the exception of the Stephanian quartz dolerite event, more magnesian than that of the earlier Carboniferous.Most of the silicic rocks of the province are silica-saturated or over-saturated, defining a trend that leads to quartz-trachyte and, rarely, alkali rhyolite. However, those that are ne-normative (silica-undersaturated) define a separate trend towards phonolite. For those undersaturated compositions that are insufficiently silicadeficient to merit the term phonolite, we use the term phonolitic trachyte. The ne-3 normative cases include several notable intrusions as well as some rare lavas of relatively evolved composition. Deuteric alteration and subsequent weathering commonly make petrographical description of the more-evolved rocks difficult and they commonly contain secondary quartz. Accordingly it is possible that other silicaundersaturated evolved rocks were emplaced but are now unidentifiable.In the previous literature on the central and southern Scottish late Palaeozoic magmatism, the significance and even the existence of these two divergent petrological trends have generally not been recognised, even though they may have important implications for the magma genesis, evolution and age of the intrusions.Here we list all known phonolitic...

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The Habit of Apatite in Synthetic Systems and Igneous Rocks

Cited by 224 publications

References 0 publications

Late-orogenic Variscan magmatism: The case of quartz monzodiorite dykes from the Blanice Graben, southern Bohemia

Late-orogenic Variscan magmatism: The case of quartz monzodiorite dykes from the Blanice Graben, southern Bohemia

Thermal aspects of the origin of Hebridean Tertiary acid magmas. I. An experimental study of partial fusion of Lewisian gneisses and Torridonian sediments

Silica-undersaturated trachytic rocks of central Scotland

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