The geology, geochemistry and petrology of a number of gold deposits in the southern Appalachians
The geology, geochemistry and petrology of a number of gold deposits in the southern Appalachians
The Haile Mine and Kiff prospect are two low-grade gold deposits hosted by the volcanic and sedimentary rocks of the Carolina slate belt, South Carolina, U.S.A. Both deposits are of similar type consisting of cleavage parallel zones on intense deformation cutting finely laminated phyllites. The zones of deformation are characterized by sericite-pyrite phyllonites, featureless quartzites, zones of intense quartz veining, and, at the Haile Mine, lensoidal bodies of massive pyrite. Petrologically the phyllonites can be seen to be derived from the phyllites by progressive flattening, loss of quartz, conversion of chlorite to sericite and pyritization. The silicified rocks at the Haile Mine and zones of quartz veining at the Kiff prospect appear to have arisen by an influx of SiO2 during ductile and brittle-ductile deformation. Pyrite and molybdenite are the chief sulphides in the zones with rare sphalerite, chalcopyrite, arsenopyrite, and pyrrhotite. Gold is commonly found intimately associated with pyrite and rarely in the free state. Using ratios of immobile components to overcome chemical trends due to volume changes it is shown that the phyllonites are characterized by loss of SiO2, MgO, and MnO with enrichment in K2O, Fe (t), Au, As, Mo, Ag, and S whilst the quartzites and veined rocks are enriched in SiO2, Au, Ag, Mo, and S. The immobile element ratios are consistent with derivation of all the rocks in the zones from a phyllite protolith. The role of cleavage has been critical in formation of the mineralization and it is proposed that the mineralized zones originated by attentuation, pressure solution and shearing during folding. Formation of cleavage allowed fluids expelled during metamorphism to be focused into the zones where the interplay of physical and chemical parameters promoted precipitation of sulphides and gold. The mineralized zones lie within large linear features visible on LANDSAT and aeromagnetic surveys. The importance of these structures in localizing mineralization is emphasized and guidelines are suggested on which future exploration for similar deposits might be based. (D73022/87)
University of Southampton
1985
Tomkinson, Marcus Jeremy
(1985)
The geology, geochemistry and petrology of a number of gold deposits in the southern Appalachians.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Haile Mine and Kiff prospect are two low-grade gold deposits hosted by the volcanic and sedimentary rocks of the Carolina slate belt, South Carolina, U.S.A. Both deposits are of similar type consisting of cleavage parallel zones on intense deformation cutting finely laminated phyllites. The zones of deformation are characterized by sericite-pyrite phyllonites, featureless quartzites, zones of intense quartz veining, and, at the Haile Mine, lensoidal bodies of massive pyrite. Petrologically the phyllonites can be seen to be derived from the phyllites by progressive flattening, loss of quartz, conversion of chlorite to sericite and pyritization. The silicified rocks at the Haile Mine and zones of quartz veining at the Kiff prospect appear to have arisen by an influx of SiO2 during ductile and brittle-ductile deformation. Pyrite and molybdenite are the chief sulphides in the zones with rare sphalerite, chalcopyrite, arsenopyrite, and pyrrhotite. Gold is commonly found intimately associated with pyrite and rarely in the free state. Using ratios of immobile components to overcome chemical trends due to volume changes it is shown that the phyllonites are characterized by loss of SiO2, MgO, and MnO with enrichment in K2O, Fe (t), Au, As, Mo, Ag, and S whilst the quartzites and veined rocks are enriched in SiO2, Au, Ag, Mo, and S. The immobile element ratios are consistent with derivation of all the rocks in the zones from a phyllite protolith. The role of cleavage has been critical in formation of the mineralization and it is proposed that the mineralized zones originated by attentuation, pressure solution and shearing during folding. Formation of cleavage allowed fluids expelled during metamorphism to be focused into the zones where the interplay of physical and chemical parameters promoted precipitation of sulphides and gold. The mineralized zones lie within large linear features visible on LANDSAT and aeromagnetic surveys. The importance of these structures in localizing mineralization is emphasized and guidelines are suggested on which future exploration for similar deposits might be based. (D73022/87)
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Published date: 1985
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Local EPrints ID: 460898
URI: http://eprints.soton.ac.uk/id/eprint/460898
PURE UUID: 4c2cccd7-2473-49e9-bfb4-a17245b08379
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Date deposited: 04 Jul 2022 18:31
Last modified: 04 Jul 2022 18:31
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Author:
Marcus Jeremy Tomkinson
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