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Gahnite in the ∼3.75 Ga Isua Greens tone Belt, West Greenland

Published online by Cambridge University Press:  25 June 2018

P. W. U. Appel
P. W. U. Appel*
Affiliation:
Geological Survey of Denmark and Greenland, Copenhagen, Denmark
*
*E-mail: [email protected]
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Abstract

The Zn-spinel gahnite has been discovered in the ∼3.75 Ga Isua Greenstone Belt, West Greenland. It is light blue-green to colourless in hand specimen and colourless in thin section as opposed to most other gahnites which are dark green to brown. The gahnites from Isua have very low Fe and Mg contents, and their compositions are thus close to the endmember gahnite. The gahnite was formed, during metamorphism, from sphalerite, in the absence of Fe-rich sulphides.

Keywords

gahniteIsua Greenstone BeltGreenland
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 1 , February 2000 , pp. 121 - 124
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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References

Appel, P.W.U. (1986) Gahnite in an Archaean iron-formation, West Greenland. Mineral. Mag., 50, 175–7.CrossRefGoogle Scholar
Appel, P.W.U. (1999) Gold mineralizations in the ˜3.7–3.8 Ga Isua Greenstone Belt, West Greenland. Abstract, Gold ‘99, Trondheim. Pp. 18–19.Google Scholar
Appel, P.W.U., Fedo, C.M., Moorbath, S. and Myers, J.S. (1998) Recognizable primary volcanic and sedimentary features in a low-strain domain of the highly deformed, oldest known (˜3.7-3.8 Gyr) Greenstone Belt, Isua, West Greenland. Terra Nova, 10, 57–62.CrossRefGoogle Scholar
Atkin, B.P. (1978) Hercynite as a breakdown of staurolite from within the aureole of the Ardara pluton, County Donegal, Eire. Mineral. Mag., 42, 237–9.CrossRefGoogle Scholar
Batchelor, R.A. and Kinnaird, J.A. (1984) Gahnite compositions compared. Mineral. Mag., 48, 425–9.CrossRefGoogle Scholar
Boak, J.L. and Dymek, R.F. (1982) Metamorphism of the ca. 3800 Ma supracrustal rocks at Isua, West Greenland. Earth Planet. Sci. Lett. 59, 155–76.CrossRefGoogle Scholar
Boak, J.L., Dymek, R.F. and Gromet, L.P. (1983) Petrology and rare earth element geochemistry of clastic metasedimentary rocks from the Isua supracrustal belt, West Greenland. Rapp. Grønlands geol. Unders. 112, 23–33.Google Scholar
Craig, J.R. (1983) Metamorphic features in Appalachian massive sulfides. Mineral. Mag., 47, 515–25.CrossRefGoogle Scholar
Dietworst, E.J.L. (1980) Biotite breakdown and the formation of gahnite in metapelitic rocks from Kemio, southwest Finland. Contrib. Mineral. Petrol., 75, 327–37.CrossRefGoogle Scholar
Moorbath, S., O'Nions, R.K. and Pankhurst, R.J. (1973) Early Archaean age for the Isua Iron Formation, West Greenland. Nature, 245, 138–9.CrossRefGoogle Scholar
Myers, J.S. (1999) Protoliths of the 3.8–3.7 Isua Greenstone Belt, West Greenland EUG Abstr., p. 144.Google Scholar
Nutman, A.P. (1986) The early Archaean to Proterozoic history of the Isukasia area, southern West Greenland. Grønlands Geol. Unders. Bull., 154, 80 pp.Google Scholar
Richards, J.R., and Appel, P.W.U. (1987) Age of the ‘least radiogenic’ galenas at Isua, West Greenland. Chem. Geol., 66, 181–91.Google Scholar
Rose, N.M., Rosing, M.T. and Bridgwater, D. (1996) The origin of Metacarbonate rocks in the Archaean Isua supracrustal belt, West Greenland. Am. J. Sci., 296, 1004–44.CrossRefGoogle Scholar
Rosing, M.T., Rose, N.M., Bridgwater, D., and Thomsen, H.S. (1996) Earliest part of Earth's stratigraphic record: A reappraisal of the >3.7 Ga Isua (Greenland) supracrustal sequence. Geology, 24, 43–6.3.7 Ga Isua (Greenland) supracrustal sequence' href=https://dx.doi.org/10.1130/0091-7613(1996)024<0043:EPOESS>2.3.CO;2>CrossRef3.7 Ga Isua (Greenland) supracrustal sequence' href=https://scholar.google.com/scholar_lookup?title=Earliest+part+of+Earth's+stratigraphic+record%3A+A+reappraisal+of+the+%3E3.7+Ga+Isua+(Greenland)+supracrustal+sequence&author=Rosing+M.T.&author=Rose+N.M.&author=Bridgwater+D.&author=Thomsen+H.S.&publication+year=1996&journal=Geology&volume=24&doi=10.1130%2F0091-7613(1996)024%3C0043%3AEPOESS%3E2.3.CO%3B2>Google Scholar
Spry, P.G. and Scott, S.D. (1986) The stability of zincian spinels in sulfide systems and their potential as exploration guides for metamorphosed massive sulfide deposits. Econ. Geol., 81, 1446–63.CrossRefGoogle Scholar
Stoddard, E.F. (1979) Zinc-rich hercynite in high-grade metamorphic rocks: A product of the dehydration of staurolite. Amer. Mineral., 64, 736–41.Google Scholar
Wall, V.J. and England, R.N. (1979) Zn-Fe spinel-silicate-sulphide reactions as sensors of metamorphic intensive variables and processes. Geol. Soc. Am. Abstr., 11, No. 7, 534.Google Scholar
Williams, P.J. (1983) The mineralogy and metamorphism of some gahnite- bearing silicate inclusions in massive sulphides from Fornas, north-west Spain. Mineral. Mag., 47, 233–5.CrossRefGoogle Scholar