Corundum-Fuchsite Rocks in Greenstone Belts of Southern Africa: Petrology, Geochemistry, and Possible Origin

Schreyer, Werner; Werding, G.; Abraham, K.

doi:10.1093/petrology/22.2.191

Cited by 60 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(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

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

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

Clifford¹

1999

Mineralogical Magazine

View full text Add to dashboard Cite

show abstract

“…The same factor is probably also responsible for the virtual absence of Ni from chromian muscovite in one of the samples from the present study. Similarly, the very low abundance of bulk rock Ni in all the four corundum-chromian muscovite assemblages (whose chromian muscovite has been analysed for elements excluding Ni) from southern Africa accounts for the paucity of Ni in their chromian muscovite (see tables 2, 3 and 5 in Schreyer et al, 1981). On the other hand, the high levels of Ni (ranging up to 2220 ppm) in the chromian muscovite-bearing rocks, especially the quartzites, from Outokumpu suggest that their chromian muscovite should be richer in Ni.…”

Section: +3mentioning

confidence: 96%

“…These include the corundum-fuchsite (chromian muscovite) rocks in the greenstone belts of southern Africa (Schreyer et al, 1981;Schreyer, 1988;Kerrich et al, 1987Kerrich et al, , 1988, the chromiferous quartzites of South India (Raase et al, 1983), the breunnerite (ferroan magnesite)-quartz-chromian muscovite assemblages in Newfoundland (Chao et al, 1986), the black schists and quartzites (containing chromian muscovite ± other Cr-bearing silicates) of Outokumpu, Finnish Karelia (Treloar et al, 1987a, b), the green mica schists in the Hemlo area of Ontario, Canada (Pan and Fleet, 1991), and a variety of lithologies (quartzites, biotite schist, metsomatized ultramafic rock and vein) from Northwest Nelson, New Zealand (Challis et al, 1995). The composition of chromian muscovite from the present study differs from the previously reported examples in that it contains high concentrations of Mg (with Mg/Fe mostly falling between 4 and 9) and Ni (ranging up to 9 wt% NiO).…”

mentioning

confidence: 99%

Nickel-rich chromian muscovite from the Indus suture ophiolite, NW Pakistan: Implications for emerald genesis and exploration

Arif

Moon

2007

Geochem. J.

View full text Add to dashboard Cite

Ubiquitous veins and stockworks of quartz traverse the ophiolitic emerald-hosting, carbonate-altered ultramafic rocks in the Swat Valley. Some of the emerald-bearing quartz veins contain chromian muscovite and tourmaline. In addition, veins and clusters consisting of chromian muscovite and/or tourmaline occur in zones of carbonate-altered rocks where the quartz veins are most abundant. The chromian muscovite is characterized by high Mg/Fe ratios (4-9) and contains variable and in some cases anomalously high concentration of Ni (ranging up to 9 wt% NiO). A detailed investigation reveals that the Ni and Mg entered the chromian muscovite structure as a part of a complex coupled substitution: . The stable coexistence of quartz, chromian muscovite, tourmaline and emerald suggests that all these phases are cogenetic and precipitated from Si-rich, Al-, Be-, B-and K-bearing fluids related to a single episode of hydrothermal activity. The Mg, Cr and Ni contents in chromian muscovite were most probably extracted by the percolating hydrothermal solutions from the host carbonate-altered ultramafic rocks through wall rock reaction. The observed high variability in the Mg, Cr and Ni contents of chromian muscovite probably reflects low mobility of these elements during the hydrothermal process or a result of local equilibrium under relatively low T conditions.

show abstract

“…In specimen 62568 V203 content reaches about 1%, and Cr20 3 reaches 0.37% in specimen 62573. Vanadium-bearing margarite has not to my knowledge been reported before, although chromium-bearing varieties are known (Cooper, 1980;Schreyer et al, 1981). Y values of analyses in Table 1 are slightly high (about 4.2) but this is typical of natural margarite, which shows a slight trioctahedral character (Frey et aI., 1982), and they have no dependence on the content ofV + Cr.…”

Section: Mineral Chemistrymentioning

confidence: 97%

Vanadium-Bearing Margarite from the Lachlan Fold Belt, New South Wales, Australia

Morand

1988

Mineral. mag.

View full text Add to dashboard Cite

Margarite occurs in Ordovician black slate within the contact aureole of the Wyangala Batholith, in the Lachlan Fold Belt in New South Wales. This occurrence is the first described from New South Wales. It is a regional metamorphic mineral replacing chiastolitic andalusite, and contains up to 1.07% VzO3 and up to 0.37% Cr20 3. Vanadium and chromium here substitute for octahedral aluminium. Margarite is produced by a local reaction in which Ca and H/O are introduced into andalusite grains. There is a significant paragonite component in the margarite but negligible muscovite solid solution.

show abstract

Corundum-Fuchsite Rocks in Greenstone Belts of Southern Africa: Petrology, Geochemistry, and Possible Origin

Cited by 60 publications

References 0 publications

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

Nickel-rich chromian muscovite from the Indus suture ophiolite, NW Pakistan: Implications for emerald genesis and exploration

Vanadium-Bearing Margarite from the Lachlan Fold Belt, New South Wales, Australia

Contact Info

Product

Resources

About