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The western segment of the Boulder Lefroy fault zone in the Eastern Goldfields province of Western Australia hosts the New Celebration gold deposits (∼20,000,000t @ 2.40g/t Au for ∼ 1,500,000 oz Au). Detailed petrography and microthermometry on fluid inclusions hosted in Early (Porphyry- and Mylonite-styles) and Late (Fracture-style) gold-related quartz and quartz-carbonate veins at New Celebration revealed a progression from early methane-rich fluids, which may represent deep-crustal fault-zone fluids, to low salinity, aqueouscarbonic gold-related fluids, to late, dense, highly saline brines.

Camp- to deposit-scale alteration halos at the kilometrescale are documented in the St. Ives gold camp, the Yilgarn Craton, Western Australia. St. Ives has sulphide-oxide mineral footprints, which are interpreted to represent different hydrothermal fluids, a more reduced and a more oxidized fluid. Boundaries where reduced and oxidized fluid domains border each other are particularly suitable for gold precipitation, suggesting a redox control on gold mineralization. Oxidized zones can be identified using detailed gravity and aeromagnetic images as well as camp-scale, first-fresh-rock, multielement whole-rock geochemistry and PIMA data. Stable isotope variations also match well spatially with reduced and oxidized zones.

In the St. Ives gold camp in the Yilgarn Craton of Western Australia, several stages of hydrothermal alteration are pre-dating (epidote-calcite-magnetite 1-pyrite 1-chalcopyrite-quartz), synchronous with (plagioclase-carbonate-pyrite 1±Au±magnetite 2±hematite) and post-dating (quartz vein system-pyrite 2-chlorite) gold mineralization. Hydrothermal fluids are characterized throughout the alteration history to gain an in depth understanding of chemical processes which controlled gold precipitation and the site of gold ore bodies.

THIS Gold in 2000 volume is organized around a classification of hypogene gold deposits that emphasizes their tectonic setting and relative time of formation compared to their host rocks and other gold deposit types (e.g., Sawkins, 1972, 1990; Groves et al., 1998; Kerrich et al., 2000). The temporal division of orogenic gold deposits into Archean, Proterozoic, and Phanerozoic follows closely the recently published classification of orogenic gold deposits (Groves et al., 1998) which incorporates the previously identified “mesothermal” gold deposits. The newly recognized intrusion-related and sedex gold deposits represent new gold deposit classes even though their exact genetic classification remains open, with more research considered a priority. Proterozoic Au-only and Cu-Au-(Fe) deposits are also a relatively recently recognized class of structurally controlled epigenetic gold deposits. Particularly, the origin and classification of Cu-Au-(Fe) deposits (e.g., Olympic Dam) remains equivocal, as pointed out by Partington and Williams (2000). In fact, Kerrich et al. (2000) discuss the anorogenic iron oxide copper-gold deposits as one of six world-class gold deposit classes. Low- and high-sulfidation and hot spring epithermal gold deposits are dealt with as one genetic gold class. Alkalic epithermal and porphyry gold deposits are dealt with as a separate gold deposit class owing to their specific host-rock association and element enrichment (e.g., Mo, F, Be, Hg, W, and Sn). The gold deposit classes are described from both industry and academic points of view, with emphasis on a balanced account of the descriptive geology, genetic interpretations, exploration significance, as well as open questions and future research avenues. The volume contains 13 papers covering 10 major classes of gold deposits and three summary papers, and was presented as a Society of Economic Geologists-sponsored short course held November 10 and 11, 2000, at Lake Tahoe, Nevada. Orogenic gold ores are associated with regionally metamorphosed terranes of all ages (Kerrich and Cassidy, 1994) and are spatially linked to subduction-related thermal processes (Kerrich and Wyman, 1990)(Fig. 1). These metal concentrations formed during compressional to transpressional deformation processes at convergent plate margins in accretionary (oceanic-continental plate interaction) and collisional (continental-continental collision) orogens (i.e., Bohlke, 1982; Groves et al., 1998). In both cases hydrated marine sedimentary and volcanic rocks have been added to continental margins over a long period of collision (10 to >100 Ma). Accretionary or peripheral orogens contain gold deposits in the Archean of Australia, Canada, Africa, India, and Brazil and the Mesozoic and Cenozoic gold fields of western North America, i.e., the famous Mother Lode belt. Collisional or internal orogens contain gold deposits in the Proterozoic of Australia, North America, West Africa, and Brazil, and the famous Phanerozoic gold fields in the Variscan, Appalachian, and Alpine regions of North America and Europe. In Phanerozoic orogenic gold deposits, subduction- related thermal events, episodically raising geothermal gradients within the hydrated accretionary sequences, initiate and drive long-distance hydrothermal fluid migration.

This series of papers on a variety of ore deposits in Brazil is the outgrowth of the “First Brazilian Symposium on Metallogeny” held in Gramado, Rio Grande do Sul, in May 2005. The selection of papers mirrors quite well the range of commodities and fascinating diversity of ore deposit types Brazil has to offer. The thematic issue starts with a paper by Monteiro et al. who use detailed petrography to establish a consistent paragenetic sequence of alteration and mineralization throughout the Sossego iron–oxide–copper–gold (IOCG) deposits in the giant Carajas Mineral Province. Combined with stable isotope data, it allows the authors to constrain the spatial and temporal zoning of hydrothermal alteration and mineralization. They conclude that the Pista-SequerinhoBaiano and Sossego-Curral ore bodies formed at a deep and high structural level of an IOCG system, respectively. Significantly, the copper–gold mineralization was late in the alteration history and broadly synchronous in both ore bodies. Another contribution to the ore deposit geology of the Carajas Mineral Province is by Dreher et al. who use new geologic, fluid inclusion and stable isotope data to establish that the Igarape Bahia Cu–Au deposit displays both characteristic syngenetic VHMS and epigenetic IOCG style geological features. This controversial paper provides evidence via recent B isotope data on tourmaline that there is the distinct possibility of an involvement of a marine evaporitic source in the hydrothermal system of Igarape Bahia. The authors carefully evaluate evidence for both genetic models and correctly agree that more detailed work needs to be conducted to resolve this fascinating genetic conundrum. Souza Neto et al. provide an overview of W–Au skarns in the Serido mobile belt in the Borborema Province in northeast Brazil. Special emphasis is put on the reduced Bonfim Au–Bi–Te skarn deposit. The majority of skarns in the Serido mobile belt are oxidized tungsten skarns even though the Itajubatiba and Bonfim gold-bearing skarns display reduced features, such as pyrrhotite as predominant sulfide, garnet with high almandine plus spessartite component, and elevated gold content. PIXE data revealed that significant amounts of F (up to 9,490 ppm) are present in prograde titanite, and retrograde clinozoisite–zoisite and gold-related epidote, suggesting significant F activity in the skarn forming hydrothermal fluids. Beurlen et al. in a second paper on mineralization in the Borborema Province use Nb–Ta–(Ti–Sn)–oxide mineral chemistry as tracer of rare-element granitic pegmatite fractionation in the pegmatite-rich Borborema Province. The Borborema Pegmatite Province, with over 750 registered mineralized rare-element granitic pegmatites, is a historically important tantalum province and is currently well known for top-quality gems, such as the Paraiba Elbaite. Detailed electron microprobe analyses of pegmatite Miner Deposita (2008) 43:127–128 DOI 10.1007/s00126-007-0174-y

Recent research has shown that Archaean lode-gold deposits occur in environments that range in their metamorphic grade from prehnite-pumpellyite to lower granulite facies. Based on this data a new classification is proposed for these deposits. In this classification, shallow-level gold deposits are classed as epizonal, the so-called “mesothermal” deposits are mesozonal, and the deeper deposits, commonly in mid-amphibolite or lower-granulite terrains, are hypozonal.

Archean shallow-level lode-gold deposits in Western Australia are located in rocks of prehnite-pumpellyite to lower greenschist facies and are characterized by (1) predominantly brittle shear zones that formed well after volcanism and late in the structural history, (2) breccia-hosted lodes, (3) low-temperature ore and gangue minerals such as silver sulfosalts, stibnite, and precursor chalcedony, and (4) vertical metal zonation of the orebodies. Ore-fluid temperatures ranged from 150 to 325 °C, and a depth of em-placement of

The high-grade Flying Fox komatiite-hosted Ni sulfide deposit, located in the Forrestania greenstone belt of the Archean Yilgarn Craton, Western Australia, is hosted in a deformed and metamorphosed volcano-metasedimentary succession. Postmineralization events have sheared and modified the texture and composition of the original massive sulfide ore, creating up to 11 distinct ore shoots including massive, stringer/vein, and breccia sulfides composed of pyrrhotite, pentlandite, chalcopyrite, and variable abundances of pyrite ranging up to 40 vol %. Nickel and platinum group elements (PGE) tenor variations were investigated in two ore shoots, T4 and T5. All mineralization styles show considerable variability in Ni tenor. PGEs show strong linear correlations between Ir, Os, Ru, and Rh, but poor correlation between Pt, Pd, and Cu. The normalized molar proportions of Fe, Ni, and S, projected into the Fe-Ni-S ternary system, show a distinct linear trend of pyrite addition to a typical primary magmatic composition and no correlation with mineralization style. The high pyrite content present throughout the Flying Fox ore is also associated with elevated Cu and As contents and is interpreted to be primarily due to the addition of pyrite from circulating Fe-, S-, Cu-, and As-enriched fluids creating pyrite-pentlandite intergrowths. Localized mechanical segregation of pyrite, sulfidation of pyrrhotite to pyrite, and oxidation of pyrrhotite to pyrite + magnetite has also contributed to these increased pyrite contents, although to a lesser extent. The addition and segregation of pyrite has diluted the Ni tenor, with no evidence to suggest chemical mobilization of Ni.

A jazida de classe mundial ouro orogênico Cuiabá, no Quadrilátero Ferrífero, encaixa-se na base do greenstone beltarqueano Rio das Velhas (RVGB) que inclui um volume extenso de rochas sedimentares. A principal rocha hospedeira doouro é uma formação ferrifero bandada (FFB), carbonática e carbonosa, com andesito na base, recoberta por pelitocarbonoso (CP), ao longo da dobra Cuiabá, que é reclinada e isoclinal. Corpos de minério recentemente descobertos na minaCuiabá têm mineralização hospedada em andesito, e corpos associados a veios de quartzo. Estudos de inclusões fluidas(microtermometria, laser raman, LA-ICP-MS, cromatografia de ions) realizados no corpo de minério VQZ mostram anatureza físico-química do fluido responsável pela mineralização de ouro. Os dados foram obtidos em tipos de quartzo(Qz1, Qz2, Qz3, Qz5) das quatro gerações de veios (V1 controlados por zonas de cisalhamentos, V2 a V4 veiosextensionais; sendo V1 e V2 mineralizados) que apresentam estrutura cronológica da história evolutiva do fluidohidrotermal. Foram encontrados três tipos de fluidos: i) aquoso de salinidade baixa (2-4 wt % NaCl equiv); temperatura dehomogenização média de 220°C, ii) aquoso de salinidade moderada-alta (6-12 wt % NaCl equiv), temperatura dehomogenização média de 260°C, e iii) aquo-carbônico de salinidade moderada (6-15 wt % NaCl equiv) com 30-91,4 mol.% CO2 e 8,6-41.0 mol. % CH4, até 28 mol. % N2, e temperatura de homogenização média de 300°C. Considerando queapenas uma FIA mostra homogenização para a fase vapor, e FIAs aquosas e aquo-carbônicas são estimadas de decrepitarpara a fase vapor, os argumentos para imiscibilidaden de fase são insignificantes. Como resultado, a correção detemperatura precisou ser aplicada, e as médias calculadas de temperatura mínima de aprisionamento ficam em 360°C paraos veios de cisalhamento V1, 330°C para veios extensionais V2, 300°C para veios extensionais V3, e até 270°C para osveios tardios V4. Todas estas temperaturas estão na faixa do geotermômetro da arsenopirita, calculado entre 300 - 390°C.Análises de cromatografia iônica em Qz1-V1 revelam uma faixa de Br/Cl entre 0,71 a 0,74x10-3, 1,40 a 1,51x10-3 em Qz2-V2, 0,31 a 0,39x10-3 em Qz3-V3, e 0,73 a 0,85x10-3 em Qz5-V4. Metais base (Zn, Pb e Cu) são relativamente enriquecidos,na ordem de 100 a 1.000 ppm, nas FIAs aquosas e aquo-carbônicas em todos os tipos de veios de quartzo em Cuiabá,similar a outros depósitos orogênicos de ouro hospedados no greenstone belt Rio das Velhas. O RVGB, rico em rochassedimentares, pode ter atuado como potencial fonte desses metais base, explicando as assinaturas elevadas de Zn e Pb. Osdados físico-químicos das inclusões fluidas indicam compatibilidade com fluidos metamórficos. Embora análisesgeoquímicas e isotópicas possam implicar múltiplas fontes de fluidos associadas ao desenvolvimento da jazida Cuiabá, oconjunto de dados das inclusões fluidas não os diferenciam em sentido absoluto. Sugere-se que um modelo de dois estágiosde fluxo de fluido hidrotermal e precipitação de ouro na jazida Cuiabá envolva desenvolvimento dos veios de cisalhamentoV1 mineralizados até veios extensionais V3, por um fluido aquo-carbônico de alta temperatura em estágio inicial. Esseenvolve uma ThTRAP mínima de 290°C (Qz2-V3) até o máximo 360°C (Qz1-V1), enquanto os veios extensionais V4 sãoassociados ao fluido de estágio tardio, aquo-carbônico evoluído, de temperatura baixa (ThTRAP médio a 260°C), sendoambos desenvolvidos durante o evento arqueano D1. A interpretação acerca do mecanismo de aprisionamento por inclusõesfluidas e precipitação de ouro podem incluir: 1) imiscibilidade intermitente de fase, e 2) mistura intermitente parcial desolução salina baixa a moderada, de dois ou mais fluidos de natureza aquosa e aquo-carbônica.Estudos texturais, geoquímicos e múltiplos de isótopos de enxofre foram realizados em sulfetos do corpo de minérioFonte Grande Sul hospedado em FFB para monitar a assinatura de elementos traço em diferentes tipos de pirita nas rochashospedeiras, de singenética a epigeneticas, para inferir a natureza e fonte do fluido mineralizado. Cinco tipos de piritas sãoclassificadas com base em aspectos texturais em: esponjosa, singenética (Py1, apenas no pelito carbonoso-PC), cedo porosa(Py2, nos 3 litotipos), lisa principal (Py3, nos 3 litotipos), e lisas e isoladas, tardias (Py4 e Py5, apenas na FFB). Mapas deabundância de elementros traço mostram que a Py1 tem altas concentrações de As, Co, Ni, Pb e Ag, assim como Py2(formada pela aglutinação da Py1 no PC). As Py2 e Py3 da FFB e do metandesito têm aumento de Co e Ni, mas menor Au eAs. A Py4 é caracterizada por concentrações baixas de elementos traço, enquanto Py5 mostra novo enriquecimento. Oestudo mostra que o CP é pré-enriquecido em Co, Ni e Pb, enquanto elementos determinados como Ag, Au, Bi e As sãoapenas concentrados hidrotermalmente durante estágios avançados na FFB e no andesito. Esse fato suporta origemsingenética vs hidrotermal para elementos diferentes. Múltiplos isótopos de enxofre sugerem que os fluidos mineralizadoresrefletem mistura complexa de enxofre que evoluiu a partir de três fontes possíveis: água do mar, manto e enxofre elementarreduzido. A Py1 singenética do PC produz valores de 33S variando de -2,28 a -0,25 , separados em duas faixas: (i) -2,28a -1,97 , (ii) -0,96 a -0,25, sugerindo (i) deposição em ambiente marinho. Estas piritas provavelmente misturaram-sedepois com enxofre mantélico, ou podem ter se misturado com fluidos provenientes de rochas sedimentares profundas deassinatura positiva de 33S (ii). Esses segundo cenário é mais comum de se esperar para piritas sedimentares/diagenéticas.Piritas de estágio inicial, principal e tardio em CP, FFB e andesito indicam ter expwrimentado contínua assimilação crustalem direção a valores progressivamente mais positivos de 34S e 33S. Isto confirma evidência de uma fonte de enxofrederivada de sedimentos, o que também é indicado pelos dados de inclusões fluidas obtidos no corpo de minério VQZhospedado por andesito.Finalmente deve-se tentar integrar a evolução proposta para do fluido hidrotermal, com base no estudo de incusões fluidasno corpo de minério de VQZ, com a evolução dos tipos de pirita do corpo de minério FGS hospedado por FFB em Cuiabá.Ambas Py2 e Py3 representam o evento de pico da mineralização arqueana, sendo considerado parte di primeiro pusohidrotermal que se desenvolveu durante a formação dos veios V2 e V3, respectivamente. Isso leva em consideração: (i)concentrações mais altas de As e Au na Py2 do que na Py3; (ii) menores As e Au nas FIAs dos veios V2 em comparaçãoaos veios V1 e V4; e (iii) valores de Ag que aumentam nas FIAs de V1/V2 a V3, enquanto que as concentrações de Agindicam tendência decrescente de Py2 a Py3. Ambas Py4 e Py5 podem ser atribuídas ao segundo pulso hidrotermal, e aosveios V4 de estágio tardio não mineralizado comparando a tendência reversa de concentrações mais baixas (decrescentes)de Pb e Mn nas FIAs aprisionados em veios desse estágio final V4, com concentrações maiores (crescentes) de Pb e Mn nasPy5. Concentrações de ouro nas FIAs nos veios V4, e a ausência de Au nos tipos de Py4 e Py5 hospedados em FFB emestágio avançado sugerem que Au permaneceu no fluido e suas condições de recipitação não foram atingidas nesse estágio.Ambos os estudos mostram influência geoquímica claras do fluido mineralizador pelas unidades sedimentares do RVGBarqueano indicado i) por FIAs contendo quantidades significativas de Pb e Zn, 2) pelos tipos de pirita que demonstramclaramente enxofre de derivação sedimentar. The world-class Cuiabá orogenic Au deposit in the Quadrilátero Ferrífero is hosted at the base of the Archean Rio dasVelhas greenstone belt (RVGB) that contains an extensive volume of sedimentary rocks, being the largest undergroundmine in Brazil (5.78 Moz resources of 10.26 g/t). The main host to gold is a carbonaceous, carbonate banded iron formation(BIF), underlain by andesite and overlain by carbonaceous pelite (CP), along the reclined, isoclinal Cuiabá fold, with anaxis having a 116° azimuth dip direction and plunging between 35° and 12°. Andesite-hosted quartz vein mineralizationconstitutes recently discovered orebodies at the mine, and fluid inclusion data (microthermometry, Laser-raman, LA-ICPMS,ion chromatography) of the VQZ orebody have constrained the physico-chemical nature of the ore-forming fluid. Thedata were obtained on quartz types (Qz1, Qz2, Qz3, Qz5) from veins classified in four main generations, V1 shear vein, andV2, V3, and V4 extensional veins (V1 and V2 mineralized), providing a chronological framework for the fluid evolutionaryhistory. Three fluid types are distinguished: i) aqueous of low salinity (2-4 wt % NaCl equiv), mean homogenizationtemperature at 220°C; ii) aqueous of moderate salinity (6-12 wt % NaCl equiv), and mean homogenization temperature at~260°C; and iii) aqueous-carbonic of moderate salinity (6-15 wt % NaCl equiv), with 30-91.4 mol. % CO2 and 8.6-41.0mol. % CH4, and up 28 mol. % N2 and mean decrepitation temperature at 300°C. Since only one fluid inclusion assemblageshows homogenization into vapour, and aqueous as well as aqueous-carbonic fluid inclusion assemblages are estimated todecrepitate into the vapor phase, supporting arguments for phase immiscibility are insignificant. As a result, temperaturecorrection is applied, and calculated mean minimum trapping temperatures are 360°C in V1 shear veins, 330°C in V2extensional veins, 300°C in V3 extensional array veins, and up to 270°C in late-stage V4 veins. All these temperatures arein the range of the arsenopyrite geothermometer calculated at 300 - 390°C. Ion chromatography analyses on Qz1-V1 veinsreveal a Br/Cl range between 0.71 to 0.74 x 10-3, 1.40 to 1.51 x 10-3 in Qz2-V2, 0.31 to 0.39 x 10-3 in Qz3-V3, and 0.73 to0.85 x 10-3 in Qz5-V4 veins. Base metals (Zn, Pb and Cu) are relatively enriched in the order of 100 to 1,000 ppm inaqueous and aqueous-carbonic fluid inclusion assemblages trapped in all vein and quartz types at Cuiabá, similar to otherorogenic gold deposits hosted in the Rio das Velhas greenstone belt. This sediment-rich greenstone belt may have acted as apotential base-metal source, explaining the elevated Zn and Pb signatures. Consideration of these physio-chemical fluidinclusion data indicates the compatibility with metamorphic fluids. Although geochemical and isotope analyses mayimplicate multiple fluid sources associated with the development of the Cuiabá deposit, the fluid inclusion data set does notdifferentiate them in an absolute sense. A two-step model of hydrothermal fluid flow and gold precipitation at the Cuiabádeposit is suggested to involve the development of the mineralised mineralized V1 shear veins up to V3 extensional arrayveins by an early- stage, aqueous-carbonic, high temperature fluid. It encompasses a minimum ThTRAP at 290°C (Qz2-V3) tomaximum ThTRAP at 360°C (Qz1-V1), and the V4 extensional veins associated with an evolved, aqueous-carbonic, lowertemperature (mean ThTRAP at 260°C), later-stage fluid, all developed during the Archaean D1 shear event. Fluid inclusiontrapping mechanism and interpreted gold precipitation processes may include 1) intermittent phase immiscibilty, and 2)intermittent partial mixing of low and moderate saline, two or more fluids of aqueous and aqueous-carbonic nature.Textural, chemical and multiple sulfur isotope analyses were conducted in sulfides from the BIF-hosted Fonte Grande Sulorebody to track distinct trace element (TE) signatures from syngenetic to epigenetic pyrite types in different host units, andto deduce the nature and source of the mineralizing fluids. Five pyrite types are classified based on textural relations asspongy, syngenetic (Py1, detected only in CP), porous early-(Py2, all 3 lithotypes), smooth main-(Py3, all 3 lithotypes) andsmooth isolated and overgrown late-stage (Py4 and Py5, only BIF) variably present in metamorphosed CP, BIF andandesite. The TE abundance maps and LA-ICP-MS analyses display that Py1 yields high As, Co, Ni, Pb and Ag values,whereas Py2 (formed by agglomeration of Py1) maintains high TE with slightly less of those elements. The TEincorporation in Py3 is similar to Py1 in CP. The Py2 and Py3 in BIF and andesite have increased Co and Ni, but have lessAu and As. BIF-hosted late-stage Py4 is characterized by lower TE concentrations, whereas Py5 is further enriched in As,Bi, Co, Ni and Pb. The study shows that CP is pre-enriched in Co, Ni and Pb, whereas certain elements like Ag, Au, Bi andAs are only hydrothermally concentrated during advanced stages in BIF and andesite, supporting a syngenetic versushydrothermal origin of distinct elements. Multiple sulfur isotopes suggest that mineralizing fluids reflect a complex mixingof sulfur evolved from three possible sources: seawater, mantle, and reduced elemental sulfur. Syngenetic Py1 yields 33Svalues ranging from 2.28 to 0.25 , separated into two ranges, (i) 2.28 to 1.97 , (ii) 0.96 to 0.25 , whereby (i)suggests the deposition in seawater environment. These pyrites probably mixed with later mantle sulfur or could have mixedwith fluids sourced from sedimentary rocks at depth carrying a positive 33S signature (ii). The second scenario is morecommon in sedimentary/diagenetic pyrite. Early-, main- and late-stage pyrites in CP, BIF and andesite present a continuousprocess of crustal assimilation towards positive 34S and 33S values. This confirms evidence for a sedimentary-derivedsulfur source as also indicated by FI data of the andesite-hosted VQZ orebody.Finally we attempt to integrate the fluid-inclusion-based, two-step hydrothermal fluid evolution with that of the pyriteevolution at Cuiabá. Both Py2 and Py3 represent the peak of Archaean gold mineralization event, and considered part of thefirst hydrothermal pulse having evolved during the development of V2 and V3 veins, respectively. This takes intoconsideration: (i) higher As and Au concentrations in Py2 than in Py3; ii) lower As and Au in FIAs of V2 veins compared toV1 and V4 veins; and (iii) Ag values that increase in FIAs from V1/V2 to V3 veins, while Ag concentrations indicate adecreasing tendency from Py2 to Py3. Both Py4 and Py5 are attributed to the second hydrothermal pulse, and the nonIIImineralized late-stage V4 veins by comparing the reverse trend of lower (decreasing) Pb and Mn concentrations in FIAstrapped in V4 and higher (increasing) Pb and Mn in Py5. Gold in FIAs in V4, and the lack of Au in BIF-hosted Py4 and Py5suggest that Au remained in the fluid and its precipitation conditions were not attained at this stage.Both studies show clear geochemical influences of the ore-forming fluid by the sedimentary units of the Archaean RVGB,indicated by 1) FIAs containing significant amounts of Pb and Zn; and 2) pyrite types that clearly demonstrate asedimentary-derived sulfur signature.