Bibliography : leaves 347-364. / xvi, 364, [58] leaves, [15] leaves of plates : ill. (some col.), maps (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A stratigraphically-based study of the nature of the shelf succession and its relationship to surrounding successions of the central Carpentaria Basin and the Great Artesian Basin as a whole. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1995

Thesis (Ph.D.) -- Memorial University of Newfoundland, 1987. / Typescript. Bibliography: leaves 448-477. Also available online.

The aim of the research focuses on characterizing heavy mineral assemblages and interpretation of the provenance of the Ecca Group of in the Eastern Cape Province, South Africa. In South Africa, the Ecca Group outcrops extensively in the Main Karoo Basin. Mudstone, siltstone, sandstone, minor conglomerate and coal are the major constituent lithologies within the group. For descriptive purposes, the Ecca is categorized into three different geographical areas: the southern area, the western and northwestern area and the northeastern area. Six of the sixteen geological formations, namely the Prince Albert, Whitehill, Collingham, Ripon, Fort Brown, Waterford and Koonap Formations are present in the study area and are best exposed in road cuttings. For purposes of comparison, the underlying Witteberg Group, the Dwyka (which has Formation status here), and the overlying Koonap Formation of the Beaufort Group, are included in the study. This study is motivated by the relatively little information that is available on the heavy minerals of the Ecca Group, and that research of this nature had not been undertaken in the study area before. Another contributing motivation was to determine whether heavy mineral assemblages could be used to identify formations of the Ecca Group and for correlating between different localities in accordance with studies done elsewhere. Additionally, diagnostic heavy mineral assemblages could aid with stratigraphic selection of future boreholes in the Ecca Group. Heavy minerals are natural provenance tracers because of their stable nature and hydrodynamic behaviour. They are both non-opaque and opaque, with apatite, epidote, garnet, rutile, staurolite, tourmaline and zircon being good examples of non-opaque grains while ilmenite and magnetite are the most common opaques. Heavies are either derived from stable minor accessory minerals or from abundant but unstable mafic components of the host rock. They are very useful in interpreting the provenance due to the fact that some minerals are diagnostic of certain source rocks. However, sediments are exposed to several factors (conditions) such as weathering, erosion, breakage due to abrasion, mixing and recycling during transportation from the source to the depositional area. This implies that there are parameters other than the parent lithology that determine their final composition.

M.Tech. (Extraction Metallurgy) / The discovery of gold at Langlaagte in 1886 led to the development of gold mining in the Far West Rand in 1934. When shafts were sunk, water from the dolomites posed a serious threat to mining. Despite cementation that sealed the many fissures, water still found its way into the underground workings. This led to the “uniform” policy of dewatering. The farming communities in the area that were dependent on the ground water had to be considered, as they had lost their livelihood. As the water levels lowered, dolines and sinkholes were formed, posing a serious threat to life and property. When the mines eventually cease to operate, be it due to high working costs, or the declining grade of the ore body, the re-watering of the dolomitic compartments will occur as a natural consequence. When water comes to within six metres of the original water level, ground instability, the formation of dolines and sinkholes, both new and existing, will occur, threatening the important rail link between Pretoria and Cape Town as it passes through Far West Rand, as well as the N12 between Johannesburg and Potchefstroom, as well as the N14 which lies to the east connecting the Gauteng Province and the North West Province. The dewatering of the compartments caused the soil which formed the roof of the cavities to dry. Re-watering will cause this dry, stable material to become wet and unstable. Where mixtures of slime and/or other material, which is not part of the geological composition of that area was used, the same phenomenon will apply. A further complication is caused by the slimes dams which are unlined. In fact, some of the slime dams were deliberately constructed over cavernous dolomite. This large mass of mine tailings over the dolomitic aquifers will “liquefy”. If the re-watering is not carefully managed the rising water table will undoubtedly trigger a rash of new sinkholes, with catastrophic consequences for unsuspecting communities that may have been established in sensitive areas. The results of previous investigations by the Departments Minerals, Energy and Water Affairs who, due to the loss of institutional memory, might not be able to find the relevant information. Other organizations such as the Council for Geoscience could be using the results for consultancy. The information should be digitized and be available to the broader South African public. FWRDWA is currently in charge of monitoring events in the area. Levelling observations have been carried out quarterly and, so far the movement of ground is minimal. The potential hazard of ground instability will recur with the re-watering of the dolomitic compartments of the Far West Rand. To support what could happen, reference is made to events which took place in the late seventies when the Far West Rand had an above average rainfall. The Donaldson Dam overflowed into the Wonderfontein Spruit and into the dewatered Venterspost compartment. As a result, the water level of the Venterspost Compartment rose rapidly which led to the re-activation of sinkholes and the formation of new ones in the Venterspost area. In the present work levelling has been carried out along most of the loops affected and the results of the levelling give an impression that the surface is currently relatively stable. This Dissertation is presented as an attempt to alert the authorities to the potential dangers if the post mining period is not carefully monitored and insufficient provision made to deal with potential contingencies.

No description available.

The geology of the Shamrocke area is described relative to its regional setting and position within the stratigraphic succession of the Lomagundi System. The stratigraphy in the immediate vicinity of the Shamrocke Mine is detailed and discussed relative to the work of others south of the project area and in other regions. The petrography of the rocks of the Shamrocke Mine area is described and the results of a great deal of mineralogical work recorded. Maps of the project area are presented at various scales from field and photogeological evidence. The thesis area is situated on the South Zambezi Escarpment of Rhodesia, and the geology described included the basaI succession of the Lomagundi System and the pre-Lomagundi Escarpment Series. The Shamrocke Mine is located on a copper orebody associated with a granulite or granofels zone within the Dolomite Series of the Lomagundi System. This ore zone granulite appears to be a metasomatised calcareous grit some 1000 feet above the upper contact of the Deweras Series (basal Lomagundi) and, within the graphitic schist and phyllite, below a dolomitic horizon in the Dolomite Series. The Lomagundi succession in the Mine area unconformably overlies the pre-Lomagundi gneiss and meta-arkose of the older, metamorphosed and deformed Escarpment Series. The basal meta-arkose, meta-quartzite and coarse schist of the Deweras Series ascends southwards through the Dolomite Series (graphitic phyllite and schist, granulite, calcareous grit, dolomite, limestone), and the Argillaceous Series (schist, phyllite, quartzite), the beds dipping steeply to the south at an angle of between 50º and 70º. Post-Lomagundi plagioclase amphibolite (altered, intrusive meta-diabase) forms Iarge semi-concordant and transgressive sills throughout the area, particularly along the contact between the Deweras and Dolomite Series. The Shamrocke Mine is on the northern limb of a large synclinal structure, the Rusere Syncline, which forms a large embayment of Lomagundi rocks into the pre-Lomagundi gneisses and granodiorites northeast from the Mine. The fold is overturned to the east and southeast. The copper mineralisation within the area and in the areas to the south is considered to be invariably associated with the basal rocks of the Lomagundi System. It occurs within both the Deweras and Dolomite Series rocks and more often than not Iies close to the contact between these two Series. The sulphide mineralisation of the Shamrocke orebody is considered, from the results of the present study, to be metasomatically emplaced during carbonate metasomatism, either from an extraneous source or from within the ore zone rock itself. The present writer favours the origin of the copper sulphide to be original syngenetic sulphide of the basal rocks of the Lomagundi depository, which has been mobilised and metasomatically relocated, possibly by the effects of regional metamorphism related to intense deformation. It is perhaps not fortuitous that the majority of the copper occurrences in the area occur where the basaI beds of the succession have been cross-folded. The copper ore comprises a simple suite of minerals, the main constituents being chalcopyrite, cubanite and pyrrhotite. The deposit is compared relative to the other copper deposits of the Lomagundi System.

This study is an account of the stratigraphic sequence, the petrography, mineralogy (microprobe investigations of orthopyroxene, clinopyroxene, olivine and plagioclase feldspar), and whole-rock major- and traceelement geochemistry of the silicate cumulates of the Upper Critical Zone in the western Bushveld Complex. Two parts of the study - an investigation of a 350m column incorporating the MG3 and UGI Footwall Units, and a comparison of two additional Upper Critical Zone profiles with a previously compiled profile between the UGI and Bastard Units - are focused on RPM Union Section in the northwestern sector of the Complex. The third part is a detailed vertical and lateral investigation of the Bastard Unit at the top of the Critical Zone, which draws on sampling and data compilation from seventeen profiles in the western limb of the Complex. The MG3 Unit (45m) is made up of a lower chromitite layer overlain by a norite-pyroxenite-anorthosite sequence while the UGlFW Unit (295m) is composed of a related series of lower chromitite layers (MG4) overlain by a pyroxenite-norite-anorthosite sequence capped by the UGI chromitite layer. These mafic cumulates display a distinctive pattern of oscillating cryptic variation in whole-rock Mg/(Mg+Fe), FeO/Ti0₂, Cr/Co and Ni/V ratios through the sequence. Sympathetic oscillations are recorded for compositions of orthopyroxene and plagioclase feldspar and eight subcycles are recognised through the UGlFW Unit. The entire sequence is characterised by the presence of small, spheroidal, embayed and irregularly shaped plagioclase grains which are poikilitically enclosed in cumulus orthopyroxene grains of both pyroxenites and norites. This texture is indicative of partial resorption of pre-existing feldspar primocrysts within the melt prior to their being incorporated into the host orthopyroxene grains. Textural, geochemical and isotopic data suggest that this sequence was built up by periodic additions of fresh, relatively primitive liquid into fractionated resident liquid, and subsequent mixing within the magma chamber. The Bastard Unit sequence, described in Chapter 4, is the last and most complete cyclic unit (c. 60m) of the Critical Zone, and its upper contact defines the boundary between the Critical and Main Zones of the Complex. This Unit can conveniently be sub-divided into a lower part, where orthopyroxene occurs as a cumulus phase, and the upper part which is composed entirely of anorthosite (Giant Mottled Anorthosite). The basal part of the Unit (≤ 18m) comprises a thin chromitite layer < O.5cm) overlain by a pyroxenite-melanorite-norite-leuconorite sequence. The basal pyroxenite is orthocumulate in character and rapidly gives way to norites and leuconorites. A distinct threefold subdivision emerges within the Giant Mottled Anorthosite which is predominantly an adcumulate which becomes orthocumulate in character at its top. Apart from minor deviations in thicknesses these lithologies are recorded over the entire strike-length covered in this study. Profiles of cryptic variation are compiled for orthopyroxene, plagioclase and whole-rock data and show that the Bastard Unit displays a characteristic pattern which is maintained throughout the western Bushveld Complex. A minor yet distinctive reversal in cryptic variation is revealed at a level which is stratigraphically variable within the lower Giant Mottled Anorthosite, and results in a double cuspate pattern. A remarkable feature of the basal Bastard pyroxenites is that although the modal proportion of mafic to felsic constituents varies systematically away from the northwestern sector, the Mg/(Mg+Fe) ratio of orthopyroxenes remains constant at 0.804 over a lateral strike distance of 171km. Within the upper part of the Unit the orthopyroxene is markedly Fe-rich and it is here that inverted primary pigeonite appears for the first time as a cumulus phase. In addition, K-feldspar, oscillatory zoned plagioclase grains and high levels of incompatible trace elements are noted at this level. On the basis of the data presented it is concluded that the Bastard Unit represents the crystallisation of a final, relatively large influx of hotter primitive liquid, with upper Critical Zone affinities, and subsequent mixing with a column of cooler (less dense) supernatant liquid which had in part hybridized with the overlying Main Zone magma. It is hypothesised that this new liquid was emplaced as a basal flow beneath supernatant liquid and that it initiated the deposition of mafic cumulates at its base. The supernatant liquid is interpreted as representing the fractionated residuum produced by crystallisation of earlier cyclic units, with plagioclase on the liquidus, and that it contained an abundance of small plagioclase primocrysts in suspension. Development of the Unit can be viewed as a two-stage process. In the lower half of the unit, chemical and physical parameters typical of the new magma dominated the crystallisation process, and resulted in cumulates very similar to other relatively complete Upper Critical Zone units. In the upper, leucocratic sequence, above a minor reversal, crystallisation was from a liquid which was the product of mixing of a minor pulse of primitive liquid with the reservoir of hybridized supernatant liquid. Although the Bastard Unit is not continuous around the entire Western limb of the Complex, it is concluded that it developed in a single, or connected, magma chamber and that its irruptive feeder zone was located in the proximal northwestern facies of the Complex.

The Mount Ayliff Complex (MAC) is situated on the border between Kwa-Zulu Natal and the Eastern Cape provinces in the Republic of South Africa, approximately 90 km due west of Port Shepstone. The Complex forms part of the Karoo Igneous Province and includes five lobes (Ingeli, Insizwa, Tonti, Tabankulu, and Horseshoe) that are the remnants of a single continuous intrusive sheet that had an original extent of 18,000km2• The current outcrop is estimated at 800km2• The lobes all show extensive internal differentiation, from basal ultramafic cumulates to diorites and monzonites at the top, while most other intrusions in the Karoo Igneous Province cooled rapidly enough to produce relatively homogenous dolerites. Most work conducted on the Complex thus far has centered on the Insizwa lobe due to the presence of a Ni-sulphide occurrence near the base of the lobe at Waterfall Gorge. The setting of the ores has analogies to the Noril'sk-Talnakh deposits, which has raised considerable exploration interest on the Mount Ayliff Complex over the last century. The current study investigates the Ni-Cu sulphide potential of the Ingeli and Horseshoe lobes, which have been poorly studied in the past. To this effect, a stream sediment survey was conducted around the Ingeli lobe to try and detect potentially hidden magmatic sulphide ores. Further, the five lobes of the Complex have been compared in terms of lithology and lithogeochemistry. Analytical techniques used for the current study include: XRF, ICP-MS and electron microprobe. Stream sediment samples were analysed using XRF and ICP-OES. Olivines from the ultramafic cumulates of the Ingeli and Insizwa lobes are undepleted in Ni, whereas olivines from the Horseshoe and Tabankulu lobes are strongly depleted in Ni. This suggests that the rocks of the latter two lobes crystallized from parental magmas that interacted with a sulphide liquid and that the magmatic flow direction was from the north to the south. The data indicate that the ultramafic rocks of the Complex plot on or near control lines between olivine and Karoo dolerite indicating that the rocks are mixtures of cumulus olivine and trapped melt of Karoo dolerite composition. There appears to be a copper enrichment towards the top of the ultramafic package in the Ingeli lobe. This pattern corresponds to other studies conducted in the InsiZWa lobe and suggests that the two lobes had originally been connected. The lowermost cumulates of the Ingeli lobe contain an enhanced crustal component suggesting some in situ contamination. No significant sulphide enrichments were encountered in the Basal Zone rocks of the Ingeli lobe. However, the stream sediment data indicate localized PGE enrichment indicating the possible presence of a localized hidden sulphide occurrence of the type found at Waterfall Gorge. Small amounts of sulphides were found associated with the Basal Zone rocks in the Horseshoe lobe consistent with the trends of Ni-depletion of olivines. However, a lack of Co depletion in the ultramafic rocks of this lobe suggests that any sulphide segregation event that did take place was of a relatively small scale. / Dissertation (MSc)--University of Pretoria, 2006. / Geology / MSc / Unrestricted

Thesis (M. Sc. (Geology)) -- University of Limpopo, 2021 / The Glentig, Alma and Swaershoek Formations were deposited after the emplacement of the Bushveld igneous complex (BIC). The sediments accumulated in what is termed as the proto-basin of the Waterberg Group. The Glentig Formation is an unconformity-bounded formation that is overlain by the Swaershoek and Alma Formations of the Waterberg Group. This study revisited the stratigraphy and put perception on the petrography, lithofacies, provenance, paleoweathering, tectonic setting and source rock characteristics of the lower parts of Waterberg Group (Swaershoek and Alma Formations) and Glentig Formation. The methodologies employed in achieving the aforementioned goals include stratigraphical analysis, petrographical and modal composition analyses, lithofacies analysis and geochemical analysis. In the study area (northeast of Modimolle town), the Glentig Formation lies or bounded between the Swaershoek Formation and Schrikkloof Formation of the Rooiberg Group. The Glentig, Swaershoek and Alma Formations attained a maximum thickness of about 400 m, 300 m and 190 m, respectively. Based on the stratigraphical analysis, the Swaershoek, Alma and Glentig Formations can be correlated. The basis for the correlation rests solemnly on the similarities in the lithological characteristics that can be found in the three formations. Six facies were identified based on lithofacies analysis. The lithofacies are grouped into 2 facies association (FA1 and FA2). The two facies associations are FA1: Conglomerate and massive sandstone, and FA2: Cross-bedded sandstone, and planar cross-bedded sandstone. Sedimentological characteristics of the identified facies associations are interpreted as debris flow, and longitudinal and transverse bars (fluvial channel deposits). Petrography and modal composition analyses indicate that the detrital components of the sandstones are dominated by monocrystalline quartz, feldspar and lithic fragments. The sandstones of the Swaershoek, Alma and Glentig Formations can be classified as subarkosic arenite and lithic arkosic arenite. Also, provenance analysis indicates that the sandstones are derived from both felsic igneous provenance and intermediate igneous provenance. The modal composition analysis and geochemical tectonic setting discrimination diagrams show that the sediments are from both the passive and active continental margin tectonic settings. Also, the geochemical data of major and trace elements suggested that the studied formations have been derived from the same provenance source area. The indices of weathering indicated that the studied rocks have been subjected to moderate to the high degree of chemical weathering. Keywords: Geology, geochemistry, Glentig, Swaershoek, Alma, Waterberg Group, South Africa / Mining Qualification Authority (MQA)

Thesis (MSc) -- Stellenbosch University , 1995. / ENGLISH ABSTRACT: A number of small greenstone bodies of the Bridgetown Formation are exposed as elongated lenses and dykes within metasediments of the Malmesbury Group in the Western Cape Province, South Africa. The Malmesbury Group is part of the Neoproterozoic to Cambrian (Namibian) Saldania Subprovince which is the southern continuation of a Pan-African mobile belt system. A detailed geological and geochemical study was conducted on the largest outcrop of the Bridgetown Formation, situated 20km east of the town Moorreesburg. The Bridgetown Formation consists of a meta-volcano-sedimentary sequence that experienced polyphase deformation and metamorphism up to the lower greenschist facies. Tectonically, the Bridgetown Formation is included in the Boland tectonic domain, east of the Piketberg-Wel lington fault zone that is suggested to run Skm west of Heuningberg and subparallel to the Berg River. This agrees with Rabie's (1974) original subdivision of the tectonic domains. The Bridgetown Formation consists of: i) A basal unit of poorly differentiated alkaline metabasalt with a within-plate tectonomagmatic fingerprint. ii) An intermediate unit of poorly differentiated tholeiitic metabasalt, intruded by a younger tholeiitic metabasite with a low degree of differentiation. Both members of the intermediate unit have ocean-floor basalt (P-type MORB) and island arc basalt fingerprints. iii) An upper unit of poorly differentiated as well as more evolved alkaline metabasalts, interlayered with metatuff with an alkaline basaltic composition, metasedimentary rocks with a marine origin, and graphitic schists and muscovitequartz schists, both with a continental crust provenance. iv) An overlying metasedimentary sequence including dolomite, massive and oolitic chert, jasper and jaspilite. The Bridgetown Formation probably also comprises a lower metamorphosed ultramafic unit, indicated by the association of Ni- and Cr-rich talc bodies, Ni-and errich banded chert, chlorite schist and small dolomite-talc-chlorite bodies at Spitskop, situated directly northwest of the main greenstone body. The sequence of eruptive stages and the geochemistry of the metavolcanics resemble Hawaiian volcanism , indicated by an initial deep water stage of alkaline magmatism, followed by main tholeiitic edifice and post-caldera alkaline magmatism. Post-caldera alkaline magmatism occurred contemporaneously with deposition . of sediments and chemical precipitates (carbonates and cherts). The Bridgetown metavolcanics have no magmatic association with either the Bloubergstrand volcanics or mafic and intermediate plutonic rocks in the Malmesbury Group. However, some physical and geochemical similarities exist between the Bridgetown Formation and the age related Grootderm Formation of the Marmora Terrane (Gariep Supergroup) which is considered to represent ophiolitic material. The Bridgetown Formation probably represents segments of oceanic crust, including seamounts of oceanic islands, which were tectonically emplaced in an accretionary prism zone during subduction of oceanic crust underneath the Kalahari Craton, 600 to 700 Ma ago. This resulted in the present spatial configuration of various small greenstone bodies in the Malmesbury Group. To date no exploitable mineral deposits have been found 1n the Bridgetown Formation. However, Au and As anomalies in stream sediment and soil samples, taken in the Spitskop area, require further attention. lt is suggested that the gold and arsenic is hosted in brittle deformed clear to milky quartz veins which developed at zones of competency contrasts in all the li tholog ies in the Spitskop area. / AFRIKAANSE OPSOMMING: 'n Aantal klein groenskisliggame van die Bridgetown Formasie is blootgestel as verlengde lense en gange binne metasedimente van die Malmesbury Groep in die Wes-Kaap Provinsie, Suid-Afrika. Die Malmesbury Groep is deel van die Neoproterozo·iese tot Kambriese (Namibiese) Saldania Subprovinsie wat die suidelike voortsetting is van 'n Pan-Afrikaanse mobiele gordel sisteem. 'n Gedetaileerde geologiese en geochemiese studie is gedoen op die grootste dagsoom van die Bridgetown Formasie, gelee 20km oos van die dorp Moorreesburg. Die Bridgetown Formasie bestaan uit 'n metavulkanies-sedimentere opeenvolging wat pol ifase vervorming en metamorfisme tot en met die laer groenskis fasies ondergaan het. Die Bridgetown Formasie word hier in die Boland tektoniese domein ingedeel deur die Piketberg-Wellington verskuiwingsone 5km wes van Heuningberg, subparallel a an die Bergrivier, te plaas. Dit stem ooreen met Rabie ( 197 4) se oorspronkl ike verdeling van die tektoniese domeine. Die Bridgetown Formasie bestaan uit: i) 'n Basale eenheid wat hoofsaaklik bestaan uit min gedifferens ieerde alkali-metabasalte met binneplaat tektonomagmatiese eienskappe. ii) 'n lntermediere eenheid wat bestaan uit min gedifferensieerde tholeiitiese metabasalt en 'n jonger intrusiewe tholeiitiese metabasiet wat 'n lae graad van differensias ie ondergaan het. Beide intermediere eenhede het oseaanvloer-basalt (P-t ipe MORB) en eilandboog basaltiese eienskappe. iii) 'n Boonste eenheid wat bestaan uit min gedifferensieerde asook meer gedifferensieerde alkal i-metabasalte, tussengelaagd met metatuf met 'n alka libasaltiese samestelling; metasedimentere gesteentes met 'n mariene oorsprong, en grafitiese ski ste en kwarts-muskoviet skiste, beide met 'n kontinentale kors oorsprong . iv) 'n Oorliggende metasedimentere opeenvolging wat dolomiet, massiewe en ooli tiese chert, jaspis en jaspiliet insluit. Die Bridgetown Formasie slu it moontlik ook 'n onderliggende gemetamorfiseerde ultramafiese eenheid in; aangedui deur die assosiasie van Ni- en Cr-ryke ta lkl iggame, Ni- en Cr-ryke gebande chert, chlorietskis en klein dolomiet-talk-chloriet liggame by Spitskop, gelee direk noordwes van die hoof groensteenliggaam. Die opeenvolg ing van magmatisme en die geochemie van die metavulkaniese gesteentes stem ooreen met Hawaiiese vulkanisme, naamlik 'n diepwater stadium, gekarakteriseer deur alkaliese magmatisme, gevolg deur 'n hoof tholeiitiese opbouing en post-kaldera alkaliese magmatisme. Die post-kaldera alkaliese magmatisme het gelyktydig plaasgevind met afsetting van sedimente en chemiese presipitate (karbonate en cherte ). Die Bridgetown metavulkaniese gesteentes het geen magmatiese assosiasie met 6f die Bloubergstrand vulkaniese gesteentes 6f mafiese en intermediere plutoniese gesteentes in die Malmesbury Groep nie. Fisiese en geochemiese ooreenkomste bestaan egter tussen die Bridgetown Formasie en die Grootderm Formasie van die Marmora Terrein (Gariep Supergroep) wat beskou word as ofiolitiese materiaal. Die Bridgetown Formasie verteenwoordig moontlik segmente van oseaankors, insluitende oseaan-eilande, wat tektonies in 'n melange sone ingeplaas is tydens subduksie van oseaankors onder die Kalahari Kraton in (600 tot 700 Mj gelede). Dit verklaar die huidige ruimte like verspreiding van verske ie klein groensteenliggame in die Malmesbury Groep. Tot en met hede is geen ontginbare mineraalafsettings in die Bridgetown Formasie ontdek nie. Au en As anomalie in stroomsediment- en grondmonsters, geneem in die Spitskop area, behoort egter verdere aandag te geniet. Daar is voorgestel dat die goud en arseen voorkom in brosvervormde helder tot melkerige kwartsare wat ontwikkel het in swak sones in al die litologie in die Spitskop area.