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Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt
Thesis (PhD)--Stellenbosch University, 2024.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614131035570176 |
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| access_status_str | Open Access |
| author | Shilunga, Josia Tulongeni |
| author2 | Kisters, Alexander |
| author_browse | Kisters, Alexander Shilunga, Josia Tulongeni |
| author_facet | Kisters, Alexander Shilunga, Josia Tulongeni |
| author_sort | Shilunga, Josia Tulongeni |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131906 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:47:09.638Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131906 Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt Shilunga, Josia Tulongeni Kisters, Alexander Stellenbosch University. Faculty of Science. Dept. of Earth Science. Hydrothermal deposits -- Fluid dynamics -- Damara Belt (Namibia) Gold mines and mining -- Namibia -- Twin Hills Gold ores -- Damara Belt (Namibia) Lithology -- Damara Belt (Namibia) -- Twin Hills deposit Economic-grade gold mineralization Geology, Stratigraphic UCTD Thesis (PhD)--Stellenbosch University, 2024. ENGLISH ABSTRACT: The high-grade metamorphic Central Zone of the Pan-African Damara Belt in central Namibia has never been recognized as a gold province despite the discovery of the Navachab gold deposit (>4 Moz) in the late 1980’s and the presence of numerous historically mined gold prospects throughout much of the Karibib region. This can be attributed to the high metamorphic grade (amphibolite- to granulite-facies) conditions, high degrees of partial melting of lower crustal levels and associated granite plutonism, or the scarcity of mafic rocks in the Damara Sequence. Exploration efforts in this terrain have faced challenges due to the diverse range of mineralization styles, different or lack of clear lithological controls, and differing structural positions. This study, in a first step, discusses the characteristics, and small- and deposit-scale controls of the recently discovered Twin Hills deposit (>3 Moz), that represents not just a new resource, but a previously unrecognized type of orogenic disseminated gold mineralization in the Pan-African Damara Belt. Furthermore, the research presents similarities or variations among individual deposits and prospects in the Karibib district that highlight the underlying controls of the regional fluid flow and gold mineralization. Much of the interpretation of this study is based on the logging of oriented drill core, limited surface mapping, 3D implicit modelling and petrographic analyses. The Twin Hills deposit is situated in subvertical and highly-strained, amphibolite-facies metaturbidites that form the subvertical limb of a regional-scale syncline, considered as the first-order controlling structure of the deposit. Sulfide and gold grains are finely dispersed in the host rocks or form networks of quartzsulfide veinlets. High gold grades are developed in (1) interbedded metapsammite packages that provide fracture permeability, and (2) zones of distinct bedding deflections, that represent dilational sites on a deposit-scale into which the regional, pervasive fluid flow was focused. These lithological and structural controls closely resemble those of orogenic gold deposits, whereas the fine-grained and dispersed texture of gold and associated sulfide mineralization are more reminiscent of disseminated gold deposits. The adjoining deposits and prospects are situated in a lithological heterogeneous, amphibolite-facies sequence of carbonates and siliciclastic units of the middle and upper Swakop Group that form steep limbs of first-order folds. The heterogeneity of the wall rocks provides the most favourable permeability structures for focused fluid flow and mineralization. Gold mineralization is hosted by numerous auriferous vein systems that show consistent variations between prospects and deposits. Economic-grade gold mineralization corresponds to a combination of lithological and structural controls: (1) contacts between rock types and formations of distinctly rheological contrasts, along which strain localization promotes fracture formation and veining in more competent rocks, (2) high-strain zones, where strain localization promoted fracturing and veining, and (3) regional-scale deviations of wall-rock structures from the main east-northeasterly Damara Belt trend. The mineralization styles and controls of mineralization of the deposits and prospects in the Karibib district bear resemblance to those observed in hypozonal orogenic gold deposits that typically form under peak-metamorphic amphibolite-facies conditions. AFRIKAANSE OPSOMMING: Die hoëgraadse metamorfiese Sentrale Sone van die Pan-Afrikaanse Damara gordel geleë in die sentrale gebied van Namibië was nog nooit erken as ‘n goud provinsie nie ten spyte van die ontdekking van die Navachab goud afsetting (>4 Moz) in die laat 1980’s en die teenwoordigheid van baie historiese ontginde goud afsettings deur ‘n groot area van die Karibib gebied. Dié kan toegeskryf word aan die hoëgraadse metamorfiese (amfiboliet tot granuliet fasies) toestande, hoë grade van gedeeltelike smelting van die laer korsvlakke en gepaardgaande granietplutonisme, of die skaarste aan mafiese gesteentes in die Damara opeenvolging. Eksplorasiepogings in die gebied het uitdagings in die gesig gestaar as gevolg van die uiteenlopende reeks mineraliseringsstyle, verskillende of gebrek aan duidelike litologiese beheermaatreëls, en die verskillende strukturele posisies. In hierdie studie, was die eerste stap om die kenmerke, en klein en afsettingskaalse beheer van die onlangs ontdekte Twin Hills afsetting (>3 Moz), wat nie net ‘n nuwe hulpbron verteenwoordig nie, maar ‘n voorheen onerkende tipe orogeniese gedissemineerde goudmineralisering in die Pan- Afrikaanse Damara gordel te bespreek. Verder, bied die navorsing ooreenkomste of variasies tussen individuele afsettings en prospekteerplekke in die Karibib distrik aan, wat die onderliggende beheermaatreëls van die regionale vloeistofvloei en goudmineralisering uitlig. Baie van die interpretasie van hierdie studie is gebaseer op die beskryfwing van georiënteerde boorkern, beperkte oppervlakkartering, 3D-implisiete modellering en petrografiese ontledings. Die Twin Hills afsetting is geleë in subvertikale en hoogs gespanne amfibolietfasiese metaturbidiete wat die subvertikale plooiflank van ‘n streekskaal sinklien vorm, die word beskou as die eerste orde beheerstruktuur van die afsetting. Sulfiede en goudkorrels is fyn versprei in die gasheerrots of vorm ‘n netwerk van kwarts-sulfied aartjies. Hoë goudgrade is ontwikkel in (1) die gelaagde metapsammiet pakkette wat breuk deurlaatbaarheid voorsien, en (2) sones van defleksies binne lae wat dilatante areas op ‘n afsettingsskaal verteenwoordig en waarin die streekdeurdringende vloeistofvloei gefokus was. Die litologiese en strukturele beheermaatreëls stem baie ooreen met dié van orogeniese goudneerslae, terwyl die fynkorrelige en verspreide tekstuur van goud en gepaardgaande sulfiedmineralisering meer herinner aan gedissemineerde goudneerslae. Die aangrensende afsettings en prospekteerplekke is geleë in 'n litologiese heterogene, amfibolietfasiese rots opeenvolging van karbonate en silisiklastiese eenhede wat deel van die middel en boonste Swakop Groep is en wat die steil flanke van die eerste orde plooie. Die heterogeniteit van die wandgesteentes bied die gunstigste deurlaatbaarheidstrukture vir gefokusde vloeistofvloei en mineralisering. Goudmineralisering word in talle gouddraende aarstelsels gevind wat konsekwente variasies tussen afsettings toon. Ekonomiese graad goudmineralisering stem ooreen met 'n kombinasie van litologiese en strukturele beheermaatreëls: (1) kontakte tussen rots tipes en formasies van reologiese kontraste, waarlangs vervormingslokalisering breukvorming en aarvorming in meer bevoegde gesteentes bevorder, (2) hoëspanningsones, waar vervormingslokalisering breking en aarvorming bevorder, en (3) streekskaalse afwykings van wandgesteente strukture van die hoof oos-noordoostelike Damara gordel neiging. Die mineraliseringsstyle en beheermaatreëls van die mineralisering van die afsettings in die Karibib distrik lyk soos dié wat in hiposonale orogenetiese goudafsettings waargeneem word, hier vorm die afsettings gewoonlik onder piek metamorfose, amfibolietfasiese kondisies. Doctoral 2025-04-08T10:00:18Z 2025-04-08T10:00:18Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131906 Stellenbosch University xxii, 114 pages : illustrations (some color), maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Hydrothermal deposits -- Fluid dynamics -- Damara Belt (Namibia) Gold mines and mining -- Namibia -- Twin Hills Gold ores -- Damara Belt (Namibia) Lithology -- Damara Belt (Namibia) -- Twin Hills deposit Economic-grade gold mineralization Geology, Stratigraphic UCTD Shilunga, Josia Tulongeni Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title | Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title_full | Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title_fullStr | Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title_full_unstemmed | Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title_short | Controls of hydrothermal fluid flow and gold mineralization in the Twin Hills deposit and adjoining areas, Central Zone, Damara Belt |
| title_sort | controls of hydrothermal fluid flow and gold mineralization in the twin hills deposit and adjoining areas central zone damara belt |
| topic | Hydrothermal deposits -- Fluid dynamics -- Damara Belt (Namibia) Gold mines and mining -- Namibia -- Twin Hills Gold ores -- Damara Belt (Namibia) Lithology -- Damara Belt (Namibia) -- Twin Hills deposit Economic-grade gold mineralization Geology, Stratigraphic UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131906 |
| work_keys_str_mv | AT shilungajosiatulongeni controlsofhydrothermalfluidflowandgoldmineralizationinthetwinhillsdepositandadjoiningareascentralzonedamarabelt |