Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-23T16:14:32.505Z Has data issue: false hasContentIssue false
  • English
  • Français

Structure of veins in a gold–pyrite deposit in banded iron formation, Amalia greenstone belt, South Africa

Published online by Cambridge University Press:  01 May 2009

J. R. Vearncombe
J. R. Vearncombe
Affiliation:
Department of Geology, Rand Afrikaans University, P.O. Box 524, Johannesburg 2000, Republic of South Africa
Get access Rights & Permissions [Opens in a new window]

Abstract

Fibrous quartz veins in deformed banded iron formation of the Amalia greenstone belt, southwestern Transvaal, are spatially related to gold–pyrite mineralization in both wallrock and vein inclusions. Poles to quartz vein orientations show a general parallelism with mineral elongation and fold plunges of the principal deformation in the wallrock. Quartz vein fibres show a consistent anticlockwise rotation, late components being subparallel to the elongation lineation, suggesting veining was probably synchronous with the principal deformation. Antitaxial fibrous veins, which dominate the mineralized banded iron formation, formed by the process of crack–seal which channelled mineralizing fluids along the vein walls, increasing the potential for fluid–wallrock interaction. Gold mineralization in quartz veins occurs in wall-parallel slivers of banded iron formation which have been plucked off the vein wall during antitaxial fibre growth. Mineralization can be explained by a process of fluid–wallrock interaction with sulphidation and gold precipitation.

Type
Articles
Information
Geological Magazine , Volume 123 , Issue 6 , November 1986 , pp. 601 - 609
Copyright
Copyright © Cambridge University Press 1986

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Durney, D. W. & Ramsay, J. G. 1973. Incremental strains measured by syntectonic crystal growths. In Gravity and Tectonics (ed. De Jong, K. A. & Scholten, R.), pp. 67–96. Wiley, New York.Google Scholar
Etheridge, M. A., Wall, V. J., Cox, S. F. & Vernon, R. H. 1984. High fluid pressure during regional metamorphism and deformation for mass transport and deformation mechanisms. Journal of Geophysical Research 89, 4344–58.CrossRefGoogle Scholar
Fleuty, M. J. 1964. The description of folds. Proceedings of the Geologists' Association 75, 461–92.CrossRefGoogle Scholar
Fripp, R. E. P. 1976. Gold metallogeny in the Archaean of Rhodesia. In The Early History of the Earth (ed. Windley, B. F.), pp. 455–66.Google Scholar
Groves, D. I., Phillips, G. N., Ho, S. E., Henderson, C. A., Clark, M. E. & Woad, G. M. 1984. Controls on distribution of Archaean hydrothermal gold deposits in Western Australia. In Gold '82: The Geology, Geochemistry and Genesis of Gold Deposits (ed. Foster, R. P.), pp. 689–712. Geological Society of Zimbabwe Special Publication no. 1. Rotterdam: Balkema.Google Scholar
Hutchinson, R. W., Ridler, R. H. & Suffel, G. G. 1971. Metallogenic relationships in the Abitibi belt, Canada: A model for Archean metallogeny. Transactions of the Canadian Institution of Metalurgy 74, 106–15.Google Scholar
Marle, O. & Brun, J. P. 1984. The curved translation path of the Parpaillon Nappe (French Alps). Journal of Structural Geology 6, 711–19.CrossRefGoogle Scholar
Phillips, G. N., Groves, D. I. & Martyn, J. E. 1984. An epigenetic origin for Archean banded-iron-formation-hosted gold deposits. Economic Geology 79, 162–71.CrossRefGoogle Scholar
Ramsay, J. G. 1980. The crack–seal mechanism of rock deformation. Nature 248, 135–9.CrossRefGoogle Scholar
Ramsay, J. G. & Huber, M. I. 1983. The Techniques of Modern Structural Geology. Vol. 1. Strain Analysis. Academic Press, 307pp.Google Scholar
Ridler, R. H. & Hutchinson, R. W. 1984. Gold in exhalites. In Archaean Gold: Barberton Centenary Symposium, Abstracts and Guide Book (ed. Pearton, T. N.), p. 18.Google Scholar
Snowden, P. A. & Watchorn, M. B. 1984. Structurally controlled gold mineralisation in the Amalia greenstone belt, western Transvaal. In Archaean Gold: Barberton Centenary Symposium, Abstracts and Guide Book (ed. Pearton, T. N.), p. 21.Google Scholar
Van Eeden, O. R., De Wet, N. P. & Strauss, C. A. 1963. The geology of the area around Schweizer-Reneke. An explanation of sheets 2724B (Pudimore) and 2725 A (Schweizer-Reneke). Geological Survey of South Africa, 76pp.Google Scholar
Wickham, J. S. 1973. An estimate of strain increments in a naturally deformed carbonate rock. American Journal of Science 273, 23–47.CrossRefGoogle Scholar