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Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt
Bibliography: leaves 94-102.
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| Format: | Thesis |
| Language: | English |
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Department of Geological Sciences
2014
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| _version_ | 1867613270872948736 |
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| access_status_str | Open Access |
| author | Board, Warwick Stuart |
| author2 | Frimmel, Hartwig E |
| author_browse | Board, Warwick Stuart Frimmel, Hartwig E |
| author_facet | Frimmel, Hartwig E Board, Warwick Stuart |
| author_sort | Board, Warwick Stuart |
| collection | Thesis |
| description | Bibliography: leaves 94-102. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/9647 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:28.738Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | Department of Geological Sciences |
| publisherStr | Department of Geological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/9647 Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt Board, Warwick Stuart Frimmel, Hartwig E Geology Bibliography: leaves 94-102. Fluid inclusion analyses of quartz veins of various generations from the outer margin of the southern Gariep Belt reveal the presence of two chemically distinct fluid populations: the pre-orogenic, rift-related Rosh Pinah ore-forming fluid and the orogenic fluids. The oreforming fluid is more saline and chemically more complex than the orogenic fluids, probably representing hot, chemically evolved hypersaline brines induced by rift-related magmatism. Four generations (D₁/D₂, D₃, D₄ and D₅) of orogenic veins are recognised on the basis of their structural relationships. The orogenic fluids are chemically similar, dominantly aqueous and generally of moderate to low salinities (<10 wt% NaCleq), with the few higher salinity estimates (10-16 wt% NaCleq) being attributed to the interaction of some of the orogenic fluids with evaporitic horizons. A trend of decreasing temperature with a decrease in age (D₄> D₁/D₂>D₃>D₅) is developed within the orogenic fluids, with the exception of those fluids related to the emplacement of the Kuboos Pluton, which yielded the highest temperatures. The D₁/D₂ fluids from the northern and Vanrhynsdorp areas were hotter than the fluids from the central area, whereas the D₃ and D₅ fluids exhibit no apparent temperature variation as a function of area. D₄ fluids show a decrease in temperature further away from the pluton. Estimates of the maximum metamorphic pressure recorded in the outer margin of the belt have been further constrained, using microthermometry results in conjunction with mineral assemblages, to 2.9-3.6 kbar, 2.9-3.1 kbar and 1.8-3.1 kbar for the northern, central and Vanrhynsdorp areas, respectively. Field observations and fluid inclusion analyses suggest channeled fluid flow on a regional rather than on an intra-formational scale, even though a rock-buffered system is suggested by oxygen isotope results. A different, largely rock-dominated fluid system was developed within the relatively impermeable carbonate units compared with the fluid system developed within the rest of the outer margin of the belt. The D₁/D₂ fluids probably represent circulating formation and metamorphic waters that were advectively forced out of the orogen and into the foreland, whereas channeled meteoric fluid flow most likely dominated during the transtensive phase of the orogeny. The D₄ fluids probably contain a magmatic component, in addition to the meteoric component. Comparisons between the ore-forming fluid and the orogenic fluids indicate that the latter have neither the required salinities, nor the required chemistry necessary in order to transport sufficient metals to produce a massive sulphide deposit the size of Rosh Pinah. The chemistry of the orogenic fluids are, however, similar to those associated with gold remobilisation and as such the potential for gold mineralisation related to these orogenic fluids should not be ruled out. Base metal sulphide exploration within the outer margin of the belt should be confined to rocks of the Hilda Subgroup. The recognition of highly saline, chemically complex nonorogenic quartz vein-hosted fluid inclusions is considered critical from the point of view of base metal sulphide exploration. 2014-11-15T19:36:25Z 2014-11-15T19:36:25Z 1998 Master Thesis Masters MSc http://hdl.handle.net/11427/9647 eng application/pdf Department of Geological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Geology Board, Warwick Stuart Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| thesis_degree_str | Master's |
| title | Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| title_full | Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| title_fullStr | Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| title_full_unstemmed | Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| title_short | Fluid evolution and mineralising potential in the outer margin of the southern Gariep Belt |
| title_sort | fluid evolution and mineralising potential in the outer margin of the southern gariep belt |
| topic | Geology |
| url | http://hdl.handle.net/11427/9647 |
| work_keys_str_mv | AT boardwarwickstuart fluidevolutionandmineralisingpotentialintheoutermarginofthesoutherngariepbelt |