Geological setting and origin of fuchsite‐bearing rocks near Menzies, Western Australia

Martyn, J. E.; Johnson, Geoff

doi:10.1080/08120098608729346

Cited by 11 publications

(5 citation statements)

References 14 publications

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“…2700 Ma lower intercept of the discordant zircon data array. Similar quartz ϩ fuchsite Ϯ Al 2 SiO 5 polymorph lithologies of metasomatic origin are well known in Archean supracrustal belts, including the Broad Arrow-Menzies Supracrustal belt, Yilgarn Craton, and the Abitibi Supracrustal belt, Superior Province (for example, Fryer and others, 1979;Martyn and Johnson, 1986). These occurrences include examples of Cr-mobilization from mafic to ultramafic lithologies and enrichment in metasomatically altered felsic igneous rocks (Martyn and Johnson, 1986;Schandl and Wicks, 1993), quartz-fuchsite veins formed by fluids associated with precious-metal mineralization (for example, Fryer and others, 1979) and hydrothermal alteration assemblages associated with volcanogenic massive sulfide deposits (Schandl and Wicks, 1993).…”

Section: Exhumationmentioning

confidence: 64%

Eoarchean to Neoarchean evolution of the Nuvvuagittuq Supracrustal belt: New insights from U-Pb zircon geochronology

Darling¹,

Moser²,

Heaman³

et al. 2013

American Journal of Science

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The Nuvvuagittuq Supracrustal belt in northern Que ´bec is a rare ϳ9 km 2 fragment of the Earth's early crust. The belt contains a metamorphosed volcanosedimentary sequence that is at least Eoarchean in age, including amphibolites of the Ujaraaluk Unit that may have protoliths as ancient as 4400 million years old (Ma; O'Neil and others, 2012). Upper amphibolite facies metamorphism and high-strain deformation have obscured many primary field relationships and disturbed whole-rock isotope systematics, leading to debate over the interpretation of previous geochronological data. We report new SHRIMP U-Pb isotopic analyses of zircons from key meta-igneous and newly identified metasedimentary units of the belt. The analyzed samples fall into four categories: (a) felsic gneisses, including sheets interlayered with the supracrustal assemblage and a tonalitic orthogneiss at the margin of the belt; (b) a newly identified metasedimentary unit; (c) fuchsite-bearing quartz-rich layers; (d) mafic gneisses, including a garnet-biotite amphibolite from the Ujaraaluk Unit and a meta-gabbro. The felsic lithologies place constraints on the minimum age of the supracrustal assemblage; oscillatory-zoned zircons separated from a felsic orthogneiss sheet form a discordant array with an upper intercept age of 3774 ؎ 32 Ma, and the tonalitic orthogneiss yielded oscillatory zoned zircons with an upper intercept age of 3781 ؎ 11 Ma. A metasedimentary unit, dominated by quartz, albite and clinozoisite, has been identified within a lower strain domain, interfolded with amphibolites of the Ujaraaluk Unit. A sample of this unit yielded zircons with highly variable CL structures and near concordant ages of between 3390 and 3780 Ma. Zircons from a fuchsite-bearing quartz layer have oscillatory zonation similar to the orthogneiss grains, and define an upper intercept age of 3794 ؎ 16 Ma. Petrologic observations and geochemical data suggest that this lithology is a metasomatically altered felsic orthogneiss band, rather than a meta-sedimentary rock belonging to the supracrustal package. Electron microscopy of polished thin sections was used to locate zircons within 6 samples of the Ujaraaluk Unit amphibolites and two samples of meta-gabbro. Large (<500 m) zircons separated from a garnet-biotite amphibolite, together with grains from a meta-gabbro, are sector zoned and yield ages of 2700 to 2640 Ma, recording the timing of pervasive hightemperature metamorphism in the region. The new zircon U-Pb data add important new detail to the geological history of the Nuvvuagittuq belt. The volcano-sedimentary sequence and mafic-ultramafic intrusive rocks were formed prior to 3800 million years ago. Subsequent geological evolution included extensive and protracted early Archean TTG magmatism and crustal remelting, Paleo-to Mesoarchean uplift and sedimentation and Neoarchean high-grade metamorphism and regional magmatism during consolidation of the Superior craton.

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Section: Exhumationmentioning

confidence: 64%

Eoarchean to Neoarchean evolution of the Nuvvuagittuq Supracrustal belt: New insights from U-Pb zircon geochronology

Darling¹,

Moser²,

Heaman³

et al. 2013

American Journal of Science

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“…Following the classic work of Whitmore et al (1946) on parageneses bearing chromian micas (fuchsite and mariposite), Martyn and Johnson (1986) have summarized the associations and note that they include: (1) metamorphic parageneses either (a) with corundum and/or aluminosilicates that are the result of greenschist-amphibolite facies metamorphism of the products of exhalative alteration of komatiitic lavas (Schreyer et al, 1981 ;Martyn and Johnson, 1986); or (b) as the product of regional metamorphism of former (perhaps chromite-bearing) quartzite and quartz conglomerate (Frankel, 1939;Clifford, 1957b;Padget in Hotmsen et al, 1957;Leo et al, 1965).…”

Section: Discussionmentioning

confidence: 99%

Chromian illite-ankerite-quartz parageneses from the Kintail district of southern Ross-shire, Scotland

et al. 1999

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The Coire Dhuinnid fault zone contains emerald green chromian illite-ankerite-quartz rocks that are similar in appearance to the fuchsite(or mariposite)-carbonate-quartz parageneses that are commonplace in Archaean greenstone belts but which are rather rare in Phanerozoic rocks. The chromian illite contains 2.3 wt.% Cr 2 O 3 , low K 2 O (7.1À7.6 wt.%) and high H 2 O+ (5.7 wt.%), and it is a 1M polytype with 410% of an illite/smectite interstratification indicative of a formation temperature of c. 175À2008C. The host rocks contain high concentrations of Ni and Cr, and show low concentrations of Ti, Nb, Y and Zr, suggesting a former primitive mafic protolith (boninitic magma?); they are considered to be retrograde remnants of Lewisian rocks. The latter, and the associated rocks of the Moine Series, have been affected by CO 2 metasomatism that was accompanied by the addition of Ca(+Sr), Fe and Mg, and by the removal of Na from, and the addition of H 2 O to the Moine metasediments. Radiogenic isotope studies of mineral separates and whole rock from sample no. 43 yielded ages of 483+2 Ma (Ar-Ar dating on Cr illite), 413+12 Ma (K-Ar dating on Cr illite), and 322+9 Ma (Rb-Sr dating on minerals and whole rock); the significance of this discrepant pattern is discussed.

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Section: Discussionmentioning

confidence: 99%

“…(1) metamorphic parageneses either (a) with corundum and/or aluminosilicates that are the result of greenschist-amphibolite facies metamorphism of the products of exhalative alteration of komatiitic lavas (Schreyer et al, 1981 ;Martyn and Johnson, 1986);or (b) as the product of regional metamorphism of former (perhaps chromite-bearing) quartzite and quartz conglomerate (Frankel, 1939;Clifford, 1957b;Padget in Hotmsen et al, 1957;Leo et al, 1965).…”

Section: Discussionmentioning

confidence: 99%

Chromian Illite-Ankerite-Quartz Parageneses from the Kintail District of Southern Ross-Shire, Scotland

Clifford¹

1999

Mineralogical Magazine

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The Coire Dhuinnid fault zone contains emerald green chromian illite-ankerite-quartz rocks that are similar in appearance to the fuchsite(or mariposite)-carbonate-quartz parageneses that are commonplace in Archaean greenstone belts but which are rather rare in Phanerozoic rocks. The chromian illite contains 2.3 wt.% Cr20> low K20 (7.1 7.6 wt.%) and high H20+ (5.7 wt.%), and it is a 1M polytype with ~<10% of an illite/smectite interstratification indicative of a formation temperature of c. 175-200~ The host rocks contain high concentrations of Ni and Cr, and show low concentrations of Ti, Nb, Y and Zr, suggesting a tbrmer primitive mafic protolith (boninitic magma?); they are considered to be retrograde remnants of Lewisian rocks. The latter, and the associated rocks of the Moine Series, have been affected by CO2 metasomatism that was accompanied by the addition of Ca(+Sr), Fe and Mg, and by the removal of Na from, and the addition of H20 to the Moine metasediments. Radiogenic isotope studies of mineral separates and whole rock from sample no. 43 yielded ages of 483_+2 Ma (Ar-Ar dating on Cr illite), 413_+ 12 Ma (K-Ar dating on Cr illite), and 322 + 9 Ma (Rb-Sr dating on minerals and whole rock); the significance of this discrepant pattern is discussed.

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Geological setting and origin of fuchsite‐bearing rocks near Menzies, Western Australia

Cited by 11 publications

References 14 publications

Eoarchean to Neoarchean evolution of the Nuvvuagittuq Supracrustal belt: New insights from U-Pb zircon geochronology

Eoarchean to Neoarchean evolution of the Nuvvuagittuq Supracrustal belt: New insights from U-Pb zircon geochronology

Chromian illite-ankerite-quartz parageneses from the Kintail district of southern Ross-shire, Scotland

Chromian Illite-Ankerite-Quartz Parageneses from the Kintail District of Southern Ross-Shire, Scotland

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