Abstract
An undulating sheet-like granodiorite body is intrusive into sedimentary rocks and dolerite of the Karoo Supergroup north of Cradock. The top of this sheet, where in contact with dolerite, is characterised by the presence of graphite containing nodules of sedimentary origin, and by sulphide-arsenide mineralization. REE and other geochemical evidence indicate that the granodiorite and the ore-bearing horizon are genetically related, but the latter is more altered by hydrothermal fluids. Similarities in REE distribution patterns also imply very little assimilation of sedimentary material. The granodiorite displays plume-like features signifying that the material was plastic or semi-molten when segregation of the plume-like features took place. The Ni-mineralisation in the ore-bearing horizon is not linked to the MgO or Fe2O3 of the granodiorite or of the ore-bearing zone, and is regarded as a separate event of hydrothermal origin.
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Received: 26 July 1996 / Accepted: 17 March 1997
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Henning, A., van der Westhuizen, W., de Bruiyn, H. et al. Hydrothermal Cu-Ni-Au-Ag mineralization in a granodiorite sill north of Cradock, Republic of South Africa. Mineral. Deposita 32, 410–418 (1997). https://doi.org/10.1007/s001260050107
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DOI: https://doi.org/10.1007/s001260050107