Thesis (Ph. D.)--University of Sydney, 2002. / Title from title screen (viewed Apr. 23, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Geosciences, Division of Geology and Geophysics. Degree awarded 2002; thesis submitted 2001. Includes bibliography. Also available in print form.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 152-167). Also available via the Internet.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Doctor of Philosophy / This thesis provides a comprehensive account of the geology of the Archaean granitoid-greenstone terrane centred around Three Sisters in the northeastern sector of the Barberton Mountain Land. The supracrustal succession in the region comprises a diverse variety of altered volcanic and sedimentary rock types that have been correlated with the principal lithostratigraphic units of the Barberton greenstone belt (BGB) as fellows: 1) schistose basic and ultrabasic lithologies correlated with the Theespruit Formation of the Gnverwacht Group are mainly developed in a narrow unit fringing the northern margin of the BGB; 2) ferruginous shale greywacke - banded iron-formation assemblages correlated with the Jheba and Belvue Road Formations constitute the dominant Fig Tree Group imks in the region. A sec «ence or silicic » .-stavolcaniclastic rocks, now altered to a variety of micaceous schists, occurs west, north ar.a northeast of Three Sisters. Viljoen and Viljoen (1970) cc rrela ted these schists ith the Theespruit Formation. In this study, the schists have been assigned'to a new lithostratigraphic unit, referred to as the Bien Venue Formation, which forms the uppermost formation of the Fig Tree Group in the northeastern part of the BGB. Isotopic studies on zircons indicate that the schists have an age of 3256 ± Ma, which is some 200 Ma younger titan the most recent age estimates for the lower portions of the Gnverwacht Group. Chemically, the silicic schists resemble calc-alkaline rocks found in modem arcs, suggesting that the Bien Venue Formation represents a period of arc-like volcanism; and 3) conglomeratic and quartzitic rocks constitute the dominant lithologies within the Moodies Group, which uncoriorroably or paraconformably overlies lithologies of the Fig Tree and Onverwacht Groups. North of the BGB is a complex suite of granitoid rocks, previously investigated by Robb et al. (1983) who defined a large (—60 kn ng and —6 km wide), elongate plutonic body of tonalitic-to-trondhjemitic composition known as the Stentor pluton. It was suggested that this pluton is correlatable with the irondhjemite gneiss plutons that intrude the southwestern parts of the BGB. Field evidence indicates, however, that the Stentor pluton forms a much smaller (* .14 km long and ~ 4 km wide) ovoid body located immediately north of the village of Louw’s Creek. Furthermore, the pluton consists of equigranular-textured graiodiorite-adamcllite, totally unlike any of the trondhjemite gneisses. In terms of texture, mineralogy and chemical composition, the Stentor pluton closely resembles the Hebron and Berlin plutohs which constitute a phase of the Nelspruit batholith. Thus, it is concluded that the Stentor pluton also forms an integral part of the batholith. Three deformation phases have been identified. The regional event affected all stratigraphic units in response to a northerly oriented compressions! stress and gave rise to east-northeasterly trending, tight-.« 5soclinal, upright and north-verging folds that are bounded by southward-dipping longitudinal reverse faults. The regional deformation occurred both prior and subsequent to the emplacement of the Stentor pluton at circa 3100 Ma. Deformation associated with the diapiric intrusion of the Stentor pluton into the greenstone assemblage during the regional deformation pnase, led to the formation of large-scale folds that have modified earlier formed structures. The final deformation episode is manifested by the presence of nortnwest- to northeast-striking, oblique-slip normal faults that exhibit both left- and right-lateral strike-slip components. / AC 2018

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Doctor of Philosophy / This thesis provides a comprehensive account of the geology of the Archaean granitoid-greenstone terrane centred around Three Sisters in the northeastern sector of the Barberton Mountain Land. The supracrustal succession in the region comprises a diverse variety of altered volcanic and sedimentary rock types that have been correlated with the principal lithostratigraphic units of the Barberton greenstone belt (BGB) as fellows: 1) schistose basic and ultrabasic lithologies correlated with the Theespruit Formation of the Gnverwacht Group are mainly developed in a narrow unit fringing the northern margin of the BGB; 2) ferruginous shale greywacke - banded iron-formation assemblages correlated with the Jheba and Belvue Road Formations constitute the dominant Fig Tree Group imks in the region. A sec «ence or silicic » .-stavolcaniclastic rocks, now altered to a variety of micaceous schists, occurs west, north ar.a northeast of Three Sisters. Viljoen and Viljoen (1970) cc rrela ted these schists ith the Theespruit Formation. In this study, the schists have been assigned'to a new lithostratigraphic unit, referred to as the Bien Venue Formation, which forms the uppermost formation of the Fig Tree Group in the northeastern part of the BGB. Isotopic studies on zircons indicate that the schists have an age of 3256 ± Ma, which is some 200 Ma younger titan the most recent age estimates for the lower portions of the Gnverwacht Group. Chemically, the silicic schists resemble calc-alkaline rocks found in modem arcs, suggesting that the Bien Venue Formation represents a period of arc-like volcanism; and 3) conglomeratic and quartzitic rocks constitute the dominant lithologies within the Moodies Group, which uncoriorroably or paraconformably overlies lithologies of the Fig Tree and Onverwacht Groups. North of the BGB is a complex suite of granitoid rocks, previously investigated by Robb et al. (1983) who defined a large (—60 kn ng and —6 km wide), elongate plutonic body of tonalitic-to-trondhjemitic composition known as the Stentor pluton. It was suggested that this pluton is correlatable with the irondhjemite gneiss plutons that intrude the southwestern parts of the BGB. Field evidence indicates, however, that the Stentor pluton forms a much smaller (* .14 km long and ~ 4 km wide) ovoid body located immediately north of the village of Louw’s Creek. Furthermore, the pluton consists of equigranular-textured graiodiorite-adamcllite, totally unlike any of the trondhjemite gneisses. In terms of texture, mineralogy and chemical composition, the Stentor pluton closely resembles the Hebron and Berlin plutohs which constitute a phase of the Nelspruit batholith. Thus, it is concluded that the Stentor pluton also forms an integral part of the batholith. Three deformation phases have been identified. The regional event affected all stratigraphic units in response to a northerly oriented compressions! stress and gave rise to east-northeasterly trending, tight-.« 5soclinal, upright and north-verging folds that are bounded by southward-dipping longitudinal reverse faults. The regional deformation occurred both prior and subsequent to the emplacement of the Stentor pluton at circa 3100 Ma. Deformation associated with the diapiric intrusion of the Stentor pluton into the greenstone assemblage during the regional deformation pnase, led to the formation of large-scale folds that have modified earlier formed structures. The final deformation episode is manifested by the presence of nortnwest- to northeast-striking, oblique-slip normal faults that exhibit both left- and right-lateral strike-slip components. / AC 2018

The ca. 2720 Ma Vermilion, Shebandowan, Winston Lake, and Manitouwadge greenstone belts (VGB, SGB, WGB, and MGB, respectively) are located along the northern margin of the Wawa subprovince. They are interpreted to have formed in broadly similar rifted arc to back-arc environments, but their base and precious endowment and, in particular, their endowment in VMS deposits, differ markedly. These difference is metal endowment reflect differences in their metallogenic history that were examined by comparing their regional, belt-scale lithostratigraphy, chemostratigraphy, petrogenesis and tectonic history constrained by new U-Pb zircon geochronology. The MGB is the most VMS-endowed and isotopically juvenile (Pb and Nd) greenstone belt. It has a trace element chemostratigraphy that is consistent with a rifted arc to back-arc environment. The trace element chemostratigraphy of the WGB is also consistent with a rifted-arc to back arc geodynamic setting. The Winston Lake VMS deposits formed during early rifting of the arc and their timing is tightly constrained at ca. 2720 Ma by U-Pb ages of the host felsic strata and post-VMS Zenith gabbro. The Zn-dominated VMS mineralization formed from hydrothermal fluids that were <300 ° and were possibly boiling in relatively shallow water. The trace element chemostratigraphy of the VGB, SGB, and WGB indicates a plume-driven rifted arc to back-arc geodynamic settings. The composition of VMS mineralization, lithofacies, and alteration in these belts are consistent with a relatively shallower-water environment, which may have compromised VMS formation. The high-Mg andesites that are typical of, but restricted to, the SGB formed during compressional “hot” subduction, which resulted in the development of a thicker arc crust. This thicker crust may have inhibited VMS formation, but favoured the formation of magmatic sulphide and gold mineralization. New detrital and magmatic zircon U-Pb geochronology allowed comparison and correlation of lithostratigraphy and metallogeny between the greenstone belts. U-Pb ages within the VGB also defined younger, Timiskaming-type volcanic and sedimentary strata that are coeval with similar deposits in the SGB. These strata are spatially and temporally associated with gold mineralization in both belts and are coeval with similar deformation and magmatic events in the WGB and along the northern margin of the Wawa-Abitibi terrane. This indicates that the formation of Timiskaming-type pull apart basins in the northern part of the Wawa-Abitibi terrane were synchronous, and earlier than in the southern part, which is consistent with oblique convergence of the Wawa-Abitibi terrane onto the Superior Province. Detrital zircon geochronology also revealed the presence of a >2720 Ma iv zircon population within the Timiskaming-type sedimentary strata of the SGB. This is consistent with their derivation from the Wabigoon subprovince and suggests trans-terrane transport of detritus in a foreland –type basin resulting from uplift of the Wabigoon subprovince during accretion of the Wawa subprovince.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references. Also available online.

Thèse de doctorat (D.R.M.)--Université du Québec à Chicoutimi, 1998. / Document électronique également accessible en format PDF. CaQCU

The Pletersburg greenstone belt Is located In South Africa, about 300 km northeast of Johannesburg. It hosts a significant amount of gold mineralization and just over 1000 kg of gold have been produced from Its various reefs and secondary deposits. The greenstone belt is interpreted as an Archean ophiolite complex. It comprlses a volcano-sedimentary succession (the Pletersburg Group) which Is subdivided Into a basal greenstone sequence, interpreted as oceanic crust, and an upper sedimentary cover sequence. A number of major shear zones, which are thought to represent thrusts that developed during the subduction of the greenstone sequence, form an integral part of the stratigraphy . Four stages of deformation (D₁-D₄) and four phases of metamorphism (H₁-H₄) (three of which are correlatable with the peak stages of deformation) are recognized. The primary gold deposits are all shear zones related. but they are subdivided into greenstone, sedimentation and granIte-hosted types. Geographically, they occur In three distinct goldfields: Eerstellng, Roodepoort and Marbastad. The greenstone-hosted · Plenaar-Doreen shear complex Is In the Eersteiing goldfield and hosts eight gold occurrences. Within the complex, Girlie North Reef is the 640m-long "pay" section of the Girlie North shear zone. This reef is characterized, macroscopically, by a Quartz-carbonate-chlorite-sulphlde assemblage and, mlcroscoplcally, by the presence of tourmaline, arsenopyrlte and Au. Geochemical evidence Indicates that mineralizing fluids were H₂O and CO₂-bearing and rich In S, K and Al. The wall rock alteratlon was Isochemlcal but Is manifest as a change In mineralogy from a hornblende + plagioclase assemblage to an actlnollte/tremollte + Quartz + clay assemblage. This Is best developed In the hangIng wall of the reef and is thought to have been caused by hydrogen ion metasomatism. The Arsenopyrite Reef was one of the main sediment-hosted shear zone gold producers In the Harabastad goldfield. This reef Is Interpreted as the basal margin of a shear zone whose top contact Is probably represented by the Quartz Vein Reef. The shear zone consists predomonantly of quartz and carbonate, and the two "pay" reefs are characterized by tourmallne. arsenopyrite and Au. No wall rock alteration was identified In this study, Based on the mineralogy and geochemical signature of the Girlie Nortn Reef and the Arsenopyrite Reef, It Is proposed that both were formed at the $The Pletersburg greenstone belt Is located In South Africa, about 300 km northeast of Johannesburg. It hosts a significant amount of gold mineralization and just over 1000 kg of gold have been produced from Its various reefs and secondary deposits. The greenstone belt is interpreted as an Archean ophiolite complex. It comprlses a volcano-sedimentary succession (the Pletersburg Group) which Is subdivided Into a basal greenstone sequence, interpreted as oceanic crust, and an upper sedimentary cover sequence. A number of major shear zones, which are thought to represent thrusts that developed during the subduction of the greenstone sequence, form an integral part of the stratigraphy . Four stages of deformation (D₁-D₄) and four phases of metamorphism (H₁-H₄) (three of which are correlatable with the peak stages of deformation) are recognized. The primary gold deposits are all shear zones related. but they are subdivided into greenstone, sedimentation and granIte-hosted types. Geographically, they occur In three distinct goldfields: Eerstellng, Roodepoort and Marbastad. The greenstone-hosted · Plenaar-Doreen shear complex Is In the Eersteiing goldfield and hosts eight gold occurrences. Within the complex, Girlie North Reef is the 640m-long "pay" section of the Girlie North shear zone. This reef is characterized, macroscopically, by a Quartz-carbonate-chlorite-sulphlde assemblage and, mlcroscoplcally, by the presence of tourmaline, arsenopyrlte and Au. Geochemical evidence Indicates that mineralizing fluids were H₂O and CO₂-bearing and rich In S, K and Al. The wall rock alteratlon was Isochemlcal but Is manifest as a change In mineralogy from a hornblende + plagioclase assemblage to an actlnollte/tremollte + Quartz + clay assemblage. This Is best developed In the hangIng wall of the reef and is thought to have been caused by hydrogen ion metasomatism. The Arsenopyrite Reef was one of the main sediment-hosted shear zone gold producers In the Harabastad goldfield. This reef Is Interpreted as the basal margin of a shear zone whose top contact Is probably represented by the Quartz Vein Reef. The shear zone consists predomonantly of quartz and carbonate, and the two "pay" reefs are characterized by tourmallne. arsenopyrite and Au. No wall rock alteration was identified In this study, Based on the mineralogy and geochemical signature of the Girlie Nortn Reef and the Arsenopyrite Reef, It Is proposed that both were formed at the same time. Textural evidence Indicates that tourmaline, arsenopyrite and Au were all very late In the paragenesis of minerallzatlon. The presence of tourmaline also Indicates a probable granite association. It Is proposed that the maln gold mineralizing event was synchronous with the Intrusion of granitoids (and therefore also with (D₁-D₄) and (H₁-H₄) and that most of the Au was derived from felsic magma. Gold was partitioned Into a magmatic hydrothermal fluid and then transported into the greenstone belt as a chlorIde complex. These magmatiC fluids were channelled up shear zones whIch had already been mineralized with a quartz-carbonate-chlorlte - sulphide assemblage by previous metamorphic fluidS. generated during the dynamic (D₂-related) H₂-phase of metamorphism. The Au was then deposIted as the result of a change In a fluid variable, such as temperature, pH, f0₂, or the activity of Cl (some Au may have been transported In a sulphur complex and so the activity of reduced 5 could also have been Important).

Orientador: Alfonso Schrank / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-06T16:33:27Z (GMT). No. of bitstreams: 1 Spreafico_RicardoRamos_M.pdf: 74748494 bytes, checksum: 5ea89bb7faa599f44ce1b9c5c4dc8024 (MD5) Previous issue date: 2006 / Resumo: A área mineralizada a ouro de Morro da Glória, centro-norte do Quadrilátero Ferrífero, Minas Gerais, contém depósitos hospedados na sequência vulcano-sedimentar do Greenstone Belt Rio das Velhas. Estes depósitos são controlados por estruturas e condições químicas influenciadas pela formação ferrífera bandada (FFB), identificadas em mapeamento geológico de superficie na escala 1: 4000 e em análises petrográficas e de petrotexturas. A FFB está intercalada em meta-basaltos do Grupo Nova Lima, e ambos estão alterados hidrotermalmente. A sericitização é o mais importante processo de alteração e foi principalmente desenvolvido no contato de quartzo-sericita xisto com FFB da Serra do Vum Vum. Nas outras ocorrências de FFB no centro e sul da área, entretanto, a c1oritização é dominante. A carbonatação é sempre subordinada, como um estágio intermediário entre as porções c1oritizada e sericitizada. Estas transformações estão associadas à sulfetação e à mineralização aurífera, assim como ao comportamento estrutural dos litotipos durante os principais eventos deformacionais. Três fases deformacionais são propostas para explicar a evolução estrutural. Uma fase D1, caracterizada por dobras isoc1inais de flanco invertido, com eixos de atitude média 90/37, como parte de zona de cisalhamento dúctil vergente para NNW, no contexto geológico regional. Uma fase O2, caracterizada por dobras desarmônicas, parasíticas, cilíndricas ou suaves, que evidenciam cisalhamento puro confirmado pela orientação de eixo-c de grãos de quartzo de veios recristalizados em O2. A c1ivagem de fratura plano-axial S2 indica deformação sob regime dúctil-rúptil. A fase D3 é evidenciada por falhas inversas com vergência para NW. A entrada de fluidos mineralizantes teria ocorrido durante a fase DI, quando os condutos foram criados como estruturas geradas durante o cisalhamento, na forma de aberturas tensionais, que permitem a passagem de fluidos, os quais reagem com as rochas hospedeiras. Na paragênese do minério predomina a pirita. À medida que a deformação progrediu, os veios e os próprios corpos mineralizados foram paralelizados, estirados e acomodaram a foliação SI. A rotação do pacote de FFB, como um corpo mais rígido, envolvido por basaltos hidrotermalizados, agora transformados em assembléias de xistos, formou a dobra principal que forma a Serra do Vum Vum. Essa rotação leva ao aparecimento de nova estrutura planar, representada pela clivagem de fratura S2 e novas aberturas tensionais. Estas são ocupadas por fluidos, que ainda não deixaram de circular, mas que podem ter natureza um pouco distinta, mais ricos em Cu e Au. O minério é agora formado por abertura na pirita preenchida por calcopirita e ouro (minério de pirita-calcopirita-ouro). No final dos eventos de deformação as estruturas S3 foram formadas, em nível crustal mais superficial e seccionaram os corpos mineralizados. análise das estruturas geológicas feita na área mineralizada do Morro da Glória, em particular, de controles estrutural e químico, ou metalotectos, mostrou o quanto essencial é a FFB para a criação de permeabilidade estrutural, para reações de sulfetação e, juntamente, para precipitação de ouro. Este modelo de redobramento da FFB é muito importante para delinear, em superficie e sub-superfície, a geometria da FFB, hospedeira da mineralização, que é aplicável em prospecção aurífera nessa área e também na exploração regional. O mapeamento de corredores com foliação S: predominante pode direcionar descoberta de zonas de concentração preferencial de ouro durante a fase deformacional D2 / Abstract: The gold mineralized area of Morro da Glória, center-north of Quadrilátero Ferrífero, Minas Gerais, Brasil, contain deposits hosted by the volcano-sedimentary pile of the Rio das Velhas Greenstone BeIt. This deposits are controlled by structures and chemical conditions influenced by banded iron fonnation (FFB), identified in surface geological mapping in scale 1:4000 and studied by petrographic and petrofabric approaches. The FFB is interbeded in metabasalts from Nova Lima Group, and bOth are hydrothennal altered. A sericitization is the main alteration process and was mainly developed on the outer contact of FFB at the Serra do Vum Vum. On others FBB occurrences in central e south of the area, however, the chloritization is dominant. The carbonatization is ever subordinated, as an intermediary stage between the chloritized and the sericitized portions. Those transformations as played major rules even on sulphides and gold mineralization as on the structural behavior during the main deformational events. Three deformational phases are proposed to explain the structural evolution history. A DI phase, characterized by isoclinal folds of inverted limb, with averaged axis climbing of 90/37, as a part of an ductile shear zone verging to NNW, in the broad geological context. A D2 phase, characterized by tuneless, drag, cylindrical or gentle folds, which evidences pure shear confinned by the orientation of c-axis of quartz grains from recristalized veins in D2. The cleavage fracture axial planes S2 indicate deformation under a ductile-ruptile regime. The D3 phase is evidenced by inverse faults verging to NW. The onset of mineralized fluids would be occurred during the DI phase, when the conduits were formed as structures generated during shear, in form of tension gashes, allows the fluids to pass trough and react with host rocks. The ore paragenesys was pyrite droved. As the deformation as increased, the veins and the mineralized bodies stretched, becomes parallel, and accommodates the SI foliation.The rotation of the FF B package, as rigid bodies, enveloped by the hydrothermalized basalts, then transformed in ductile schist assemblages, developed the main fold that fonns the Serra do Vum Vum. This rotation leads to the development of new planar structures, represented by cleavage fractures 82 and new tension gashes. These are drained by fluids, that yet don't stopped to circulate, but can have a little distinct provenance, as it is richer in Cu e Au. Ore is now formed by broken pyrite filled by chalcopyrite and gold drops (pyrite-chalcopyrite-gold ore). Previous pyrite ore was rigid during the D2 ductile event. At the end of deformational events the S3 structures as formed, at most superficial crustallevels and has sectioned the mineralized bodies. The geological structures analysis done at Morro da Glória mineralized area, in particular, from structural and chemical controls, or metalotects, showed as essential is the FFB to allow the creation of structural permeability, the reactions of sulphidation and, besides, the gold precipitation. Also, this standard of refolded FBB is very important to delineate, in surface and underground, the geometry of FFB hosting gold mineralization, which is applicable to gold prospecting on this area but also on regional exploration. Mapping of corridors with dominant S2 foliation can drive to discover zones of preferential gold concentration during the D2 deformational phase / Mestrado / Metalogenese / Mestre em Geociências

A Thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirement for the degree of Doctor of Philosophy. Johannesburg March 2016 / This study aims to provide a comprehensive description of the Flora, biogeography and diversity of the serpentine outcrops of Barberton Greenstone Belt in Mpumalanga, South Africa in order to set conservation priorities for these areas. About 30 large and many smaller serpentine outcrops form part of the Barberton Greenstone Belt and consist of various combinations of serpentinized minerals. Seven outcrops were selected to be studied in detail. A floristic analysis recorded 744 species and subspecies, 319 genera and 94 families. The flora includes 33 taxa endemic to serpentine soils and six taxa, which are hyperaccumulators of nickel. The endemic taxa make up 41 % of the endemics of the Barberton Centre of Endemism. The serpentine flora was found to be different to the surrounding non-serpentine vegetation in terms of numbers of species per family, the ratios of dicotyledons to monocotyledons and familial composition. The Asteraceae and the Anacardiaceae support a higher number of endemics than expected, which suggests genetic pre-adaptation within these families and specifically within the genera Berkheya, Helichrysum and Ozoroa. Most of the endemic taxa exhibit long-range dispersal suggesting gene flow between populations on different outcrops. The endemics represent a mix of neo-endemics and paleoendemics. Non-parametric species richness estimators used to predict the species richness of each site, indicated that five serpentine outcrops have higher species richness than the surrounding non-serpentine areas. Indices of diversity calculated showed similar patterns to those of the species richness estimates. The Barberton Greenstone Belt serpentine outcrops show relatively high plant diversity when compared to some other serpentine outcrops around the world. Beta diversity calculated for each site was not correlated with altitude and weakly correlated with the size of outcrops. Species turnover between outcrops is high and is positively correlated with the geographical distance between outcrops. Diversity at higher taxonomic levels were calculated, and results suggest that genera have some potential for facilitating the ranking of outcrops in terms of biological richness to select sites for conservation planning. Less than 30% of serpentine outcrops are adequately conserved. Species and genus richness and endemism were used to select five outcrops that have high conservation priority / MT2016