Evolution of the Cornubian ore field, Southwest England; Part II, Mineral deposits and ore-forming processes

Jackson, Norman; Willis-Richards, J.; Manning, David; Sams, Mark

doi:10.2113/gsecongeo.84.5.1101

Cited by 108 publications

(78 citation statements)

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“…12). A similar scenario has been proposed for the intrusive sequences in the Cornubian ore field, SW England (Jackson et al 1989) or the evolution of the Mole Granite in Australia (Audétat et al 2000;Schaltegger et al 2005). Finally, the ascent path was used by another pulse of silicate magma now represented by the Betliar porphyritic granite.…”

Section: Discussionmentioning

confidence: 83%

The granite system near Betliar village (Gemeric Superunit, Western Carpathians): evolution of a composite silicic reservoir

Kubiś¹,

Broska²

2012

J. Geosci.

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Boron-and fluorine-rich highly evolved granites in the Betliar area (Gemeric Unit, Western Carpathians) represent composite intrusion that formed probably during two distinct magmatic episodes. During the first stage, evolved granitic magma originating from an underlying volatile-rich reservoir intruded into an open fault system in the form of sill-like bodies and crystallized as equigranular or medium-to fine-grained rocks. The subsequent volatile flux enhanced postmagmatic alterations of the solidified granites and led to the formation of greisens with elevated amounts of tourmaline and Nb-Ta-W-Th phases. During the second stage, magma from a deeper magmatic reservoir intruded as a mush containing K-feldspar, albite, mica and quartz phenocrysts and gave rise to porphyritic granites. Partial dissolution and corrosion of the phenocrysts was enhanced by a pressure drop during emplacement of the porphyritic granites into middle-crustal level where the volatile-rich residual melt rapidly crystallized and is now preserved as quartz-albite-K-feldspar matrix with tourmaline and other accessories. Monazite and zircon geochronology indicates that the process occurred during Middle and Late Permian, and possibly extended to Early Triassic.

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Section: Discussionmentioning

confidence: 83%

The granite system near Betliar village (Gemeric Superunit, Western Carpathians): evolution of a composite silicic reservoir

Kubiś¹,

Broska²

2012

J. Geosci.

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“…Three standard commercial grade hydrothermal kaolins, were used in this study: GB3 and Dinky A83 are well-ordered primary, granitehosted kaolinites from the Cornubian ore field of southwest England (English China Clay, St. Austell, Cornwall: Jackson et al, 1989). FCF is also granitehosted kaolinite; it comes from the Berrien ore of Brittany (Soci&6 de la Cornouaille Franqaise, Finist6re, France).…”

Section: Methodsmentioning

confidence: 99%

FTIR Reflectance vs. EPR Studies of Structural Iron in Kaolinites

Delineau

1994

Clays and clay miner.

106

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Abstract--The substitution of Fe 3+ in the kaolinite structure is studied by EPR spectrometry and by FTIR spectrometry on a large set of kaolins from different origins (sedimentary and primary ores, soil kaolins). The IR bands at 3598 and 875 cm -~, observed in the literature only in the case of disordered kaolins or in Fe-rich environments (synthetic, lateritic), are revealed by high-resolution IR analysis, whatever the origin and the total Fe content of the samples. The EPR bands corresponding to Fe 3 § substituted in sites II of the octahedral sheet increase when the IR absorbance near 3600 cm -~ increases. Two IR absorption bands near 4465 cm -~ and 7025 cm -~ are observed for the first time, both in transmission and diffuse reflectance on all samples. These bands are assigned to the combination of the 3598 and 875 cm -~ bands and to the first harmonic of the band at 3598 cm -~ , respectively. The area of the band at 4465 cm -~ in diffuse reflectance is quantitatively correlated to the abundance of Fe 3+ located in centers II as measured by ESR. This directly confirms the assignment of the two IR bands at 3598 and 875 cm -~ to OH stretching and deformation vibration bands in octahedral FE 3+ environment in the kaolinite structure, respectively. Effects due to the size of particles and to the main kaolins impurities on the near infrared spectra, are also discussed.

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“…Epithermal hydrothermal systems were involved in the development of these primary, granite-hosted kaolins (Jackson et al, 1989). These samples contain only minor amounts of 137 Fraction > 2 micrometers.…”

Section: Natural Kaolinsmentioning

confidence: 99%

Fe-Speciation in Kaolins: A Diffuse Reflectance Study

Malengreau

Müller

Calas

1994

Clays and clay miner.

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Abstract--Diffuse reflectance spectra of kaolins have been recorded in samples from different environments. They show the systematic presence of Fe-oxides, even in bleached kaolins, with no contribution from the Fe 3+ ions substituted in kaolinite. Second derivative spectra of various Fe-phases (hematite, goethite, lepidocrocite, maghemite, akaganeite, ferrihydrite and Fe-polymer) may be differentiated by the position of a diagnostic band corresponding to the 2QA0 ~ 2(4T~(4G)) transition. The systematic comparison of diffuse reflectance spectra of unbleached and bleached kaolins has demonstrated the differences between the Fe-oxides occurring as coatings and as occluded phases. The features observed in second derivative spectral curves are consistent with assignments of crystal field transitions to goethite, hematite, akaganeite, and aged hydrous ferric oxides. The optical determination of the Fe-phases associated to kaolins assists in the interpretation of the formation conditions of these minerals.

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Evolution of the Cornubian ore field, Southwest England; Part II, Mineral deposits and ore-forming processes

Cited by 108 publications

References 0 publications

The granite system near Betliar village (Gemeric Superunit, Western Carpathians): evolution of a composite silicic reservoir

The granite system near Betliar village (Gemeric Superunit, Western Carpathians): evolution of a composite silicic reservoir

FTIR Reflectance vs. EPR Studies of Structural Iron in Kaolinites

Fe-Speciation in Kaolins: A Diffuse Reflectance Study

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