Orientadores: Alvaro Penteado Crósta, Catarina Labouré Bemfica Toledo, Adalene Moreira Silva / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T00:13:09Z (GMT). No. of bitstreams: 1 Carrino_ThaisAndressa_D.pdf: 37700269 bytes, checksum: 1032551af9407d69e558467ba552091e (MD5) Previous issue date: 2015 / Resumo: O sul do Peru contém importantes depósitos epitermais de Au-Ag (±metais base) de pequeno a médio porte, associados com a orogenia Andina do Mioceno-Plioceno. Uma análise sinóptica da região abrangendo os alvos Chapi Chiara, Cerro Millo, San Antonio de Esquilache e Cerro Chucapaca ¿ localizados em distintos paleoestratovulcões¿, foi feita via processamento e análise de imagem do sensor ASTER. Todos estes alvos são caracterizados por extensas zonas de alteração argílica avançada (alunita-caulinita) (AAA), à exceção de San Antonio de Esquilache, cuja alteração argílica (AA) (esmectita/ilita) e argílica avançada se restringe a intrusões dioríticas aflorantes. Diferentemente, o depósito epitermal de sulfetação intermediária Canahuire (Au-(Cu, Ag)) foi discriminado por extensos afloramentos NW-SE de rochas quartzosas (Grupo Yura/Juro-Cretáceo), e rochas carbonáticas (Formação Gramadal/Grupo Yura) e brechas freáticas e freatomagmáticas pobres em sílica que hospedam a mineralização. Modelo de favorabilidade para depósitos "tipo-Canahuire" foi produzido a partir da integração dos produtos ASTER usando-se a lógica fuzzy. Estudo de detalhe foi realizado no prospecto Chapi Chiara usando-se petrografia, geoquímica, espectroscopia de reflectância, dados de susceptibilidade magnética (SM), imagens da amplitude do sinal analítico e da primeira derivada vertical do campo magnético anômalo, além do processamento de imagens do sensor HyMap. As principais rochas vulcânicas amostradas compreendem andesito porfirítico (SM ~28×10-3 SI), tufo e lapilli tufo de composição riolítica (SM~0). O setor SW do prospecto é caracterizado por três subáreas com extensa AAA, marcadas por quartzo, K-alunita, alunita intermediária, Na-alunita, caulinita, dickita (±topázio, ±huangita, ± minerais APS, ±pirofilita, ±diásporo, ±rutilo) (SM ~0 a ~0,15×10-3 SI). Restritas zonas de AA (quartzo, ilita ± , ilita paragonítica ± , esmectita, ±pirita, ±rutilo) (SM ~0,01×10-3 SI) e de alteração propilítica (clorita, quartzo, calcita, epidoto, esmectita, ±caulinita, ±pirita, ± calcopirita, ± titanomagnetita e magnetita)) (SM ~3,45×10-3 a ~36,03 × 10-3 SI) ocorrem em setores distais. O setor central é marcado por brechas hidrotermais métricas/decamétricas com SM ~0 a 0,01×10-3 SI, compostas de fragmentos de rochas ricos em quartzo vuggy. Há considerável concentração de pirita e forte associação geoquímica de Au, Ag, As, Bi, Hg, Se, Sb, e Te. Os principais minerais supergênicos compreendem jarosita e goethita. As assembléias minerais hipógenas acima mencionadas revelam a existência de um sistema epitermal de alta sulfetação similar ao do prospecto aurífero Cerro Millo e aos dos depósitos auríferos Tucari e Santa Rosa, permitindo a inferência de idade relativa do paleoestratovulcão e da concomitante atividade hidrotermal em Chapi Chiara entre ~11 e ~4 Ma. Intenso processo de lixiviação magmático-hidrotermal visto nas zonas de AAA e AA paramagnéticas e diamagnéticas gerou duas extensas zonas desmagnetizadas NW-SE, compatíveis com o sistema de falhas regionais Condoroma-Caylloma. Estruturas de menor magnitude também aparecem (e.g., NE-SW, E-W). Embora estes trends sejam interessantes vetores exploratórios, a exposição de minerais formados em condições de maior temperatura (e.g., alunita+topázio, alunita+dickita+pirofilita, diásporo, alunita intermediária no setor SW), sugere tratar-se de núcleos mais erodidos, reduzindo-se o potencial de mineralização local, e/ou indicando a proximidade do limite de transição do domínio epitermal para um mesotermal em profundidade, com a possível existência de intrusão(ões) diorítica(s) próxima(s) à superfície do prospecto, similarmente ao que já é observado no alvo análogo de San Antonio de Esquilache / Abstract: Southern Peru contains important small- to medium-sized Au-Ag (± base metals) epithermal deposits, associated with the Miocene-Pliocene Andean orogeny. A synoptic analysis of the region covering the Chapi Chiara, Cerro Millo, San Antonio de Esquilache and Cerro Chucapaca targets ¿ each one located in distinct paleostratovolcanoes ¿ was done through the processing and analysis of ASTER data. These targets are characterized by extensive advanced argillic alteration zones, except San Antonio de Esquilache, that is marked by argillic alteration (AA) (smectite-illite) and advanced argillic alteration (alunite-kaolinite) (AAA) zones restricted to outcropping diorite intrusions. Unlikely, the Canahuire intermediate sulfidation epithermal Au-(Cu, Ag) deposit was discriminated by extensive NW-SE quartz-rich rocks (Yura Group/Juro-Cretaceous), and carbonate rocks (Gramadal Formation/Yura Group) and silica-poor phreatic and phreatomagmatic breccias that host the mineralization. Favorability model for "Canahuire-type" deposits was created through the integration of ASTER data using the fuzzy logic technique. A detailed study was conducted at Chapi Chiara prospect through petrography, geochemistry, reflectance spectroscopy, magnetic susceptibility (MS), images of the amplitude of analytic signal and of first vertical derivative of the anomalous magnetic field, besides the processing of HyMap hyperspectral remote sensing data. The main sampled volcanic rocks comprise porphyritic andesite (MS ~28×10-3 SI), and rhyolitic tuff and lapilli tuf (MS~0). The SW sector of the prospect is characterized by three sub-areas with extensive AAA zones, marked by quartz, K-alunite, intermediate alunite, Na-alunite, kaolinite, dickite (±topaz, ±huangite, ±APS minerals, ±pyrophyllite, ±diaspore, ±rutile) (MS ~0 to ~0,15×10-3 SI). Restricted AA zones (quartz, illite ± , paragonitic illite ± , smectite, ±pyrite, ±rutile) (MS ~0,01×10-3 SI), and of propylitic alteration (chlorite, quartz, calcite, epidote, smectite, ±kaolinite, ±pyrite, ±chalcopyrite, ±titanomagnetite and magnetite)) (MS ~3,45×10-3 to ~36,03×10-3 SI) occur in distal sectors. The central sector is marked by metric/decametric hydrothermal breccias with MS ~0 to 0,01×10-3 SI, composed of vuggy quartz-rich fragments. There is a considerable concentration of pyrite and strong geochemical association of Au, Ag, As, Bi, Hg, Se, Sb, e Te. The main supergene minerals comprise jarosite and goethite. The above mentioned hypogene mineral assemblages reveal a high sulfidation epithermal system similar to the Cerro Millo gold prospect and to Tucari and Santa Rosa gold deposits, allowing to infer a relative age between ~11 and ~4 Ma for the paleoestratovolcano and the concomitant hydrothermal activity in Chapi Chiara. Intense magmatic-hydrotermal leaching seen in the paramagnetic and diamagnetic AAA and AA zones generated two NW-SE extensive demagnetized zones, compatible with the regional Condoroma-Caylloma fault system. Smaller structures also occur (e.g., NE-SW, E-W). Although these trends are interesting exploration vectors, the exposure of minerals formed at higher temperature (e.g., alunite+topaz, alunite+dickite+pyrophyllite, diaspore, intermediate alunite in the SW sector), suggest possible eroded cores, reducing the local potential for mineralization, and/or indicating the proximity of the limit between epithermal and mesothermal domains in depth. In addition, there is a possible proximity of dioritic intrusion(s) near the surface of the prospect, similarly to the currently exposed intrusions at the surface in the analogous target of San Antonio de Esquilache / Doutorado / Geologia e Recursos Naturais / Doutora em Ciências

The Little Cottonwood stock in central Utah, USA, is a composite granitic pluton that hosts the White Pine porphyry Mo-W deposit towards its northeast margin. The deposit is centered on the smaller White Pine intrusion, and associated igneous units include the Red Pine porphyry, phreatomagmatic pebble dikes, and rhyolite dikes. Twelve new U-Pb zircon LA-ICP-MS ages, for samples from this deposit and in pebble dikes from the nearby East Traverse Mountains, give peak ages of about 30 Ma and 27 Ma for the Little Cottonwood stock and White Pine intrusion, respectively, which correlate well with ages from previous studies. Ages of about 26 Ma were obtained for the previously undated Red Pine porphyry.The ages of the Little Cottonwood stock, White Pine intrusion, and Red Pine porphyry, as well as disparities in whole rock elemental differentiation trends, suggest that these units are magmatically distinct, and are not simply derivatives of one another with varying degrees of differentiation. Quench textures and resorbed quartz in the Red Pine porphyry are evidence that the magma system vented, which probably produced volcanic eruptions and emplacement of pebble dikes nearly synchronously with quartz-sericite-pyrite alteration and Mo-W mineralization. The mineralogy and geochemistry of these units imply that the magmas formed in a subduction-related magmatic arc setting rather than in an extensional basin related to orogenic collapse.Pebble dikes in the East Traverse Mountains 17 km away contain igneous clasts that resemble the units in the White Pine deposit in texture, mineralogy, and in U-Pb zircon ages. This supports other recent studies that suggest that the East Traverse Mountains rested atop the White Pine deposit prior to being displaced in a mega-landslide, and the pebble dikes in both locations are the top and bottom of the same mineralized phreatomagmatic system.The construction of the pluton began with intrusion of the Little Cottonwood stock, then the White Pine and Red Pine magmas. Fluid exsolution from the Red Pine magma accompanied venting, inception of the mineralizing hydrothermal system, and quenching to a porphyritic stock. Pebble dikes intruded into the overlying East Traverse Mountain block, which catastrophically failed millions of years later and was emplaced in its current location.

The Motzfeldt centre is one of four major alkaline centres belonging to the Igaliko complex of South Greenland. The melts parental to the Motzfeldt centre are interpreted from Hf isotopes to be derived form a common mantle source which experienced subsequent isotopic contamination from older crustal components during the interval between segregation and emplacement. Magmatism within the centre commenced with the emplacement of the Motzfeldt Sø Formation at 1273 ± 8 Ma. This unit is unique within the Motzfeldt intrusion as it is characterised by a high degree of textural and mineralogical variability and hosts localised Nb, Ta, U, Th, Zr and REE mineralisation associated with pyrochlore and late-stage REE bearing carbonate phases. Biotite halogen contents show that in addition to enrichment of incompatible elements the MSF and Motzfeldt centre in general is particularly rich in F. The elevated F content is inferred to have extended the crystallisation interval of the melt and facilitated fractionation down to relatively low temperatures. The unusual enrichment of F and incompatible elements in the MSF is suggested to represent the first and most evolved melts extracted from the top of a stratified storage chamber at depth. The MSF is also characterised by pervasive subsolidus alteration, giving the rock and region a striking brick red colour. Pb-Pb pyrochlore studies indicate that alteration in the formation was effectively synchronous (1267 ± 6 Ma), with the magmatic age of emplacement. Fluid inclusion studies suggest that contemporaneous to the exsolution of juvenile, high salinity, F-rich fluids was the wholesale influx of hydrothermally convected low salinity groundwaters through the formation. The presence of pervasive late-stage hematite and calcite throughout the MSF suggests that the oxidation potential of the bulk fluid increased above the hematite-magnetite buffer during the waning stages of the hydrothermal phase. Mineralisation was promoted by this shift in fluid composition, reducing the complexing potential of fluid ligands and facilitating mineralisation within the high-levels units of the intrusion where alteration is most intense. Economic mineralisation associated with the centre is inferred to be largely sourced from the parental melts, however the role the hydrothermal phase played was particularly important in locally mobilising and concentrating incompatible elements within the high-level units of the formation.

Sixteen samples from 8 locations within and surrounding the Björkdal mine area in northern Sweden were chosen in order to reevaluate and characterize previous interpretations of the lithology and hydrothermal alteration. Geochemical analysis by ICP-MS was made in order to chemically classify the lithology of the area and petrological studies were made by study of thin sections and core logging. Three different sets of major alteration types with similar protolith were noted where two dominated: a) a silicified, sericitic, deformed unit; b) a felspathic altered unit with various intensity of epidote; c) amphibole and a so called green banded unit that has undergone Ca-Mg-metasomatism. The main host rock lithology could be identified as a coarse grained, equigranular, plagioclase and (Na-K)-feldspar dominated rock with slightly elongated, stubby grains that have an interlocked, igneous texture. Apatite is a reoccurring accessory mineral in all samples and remains relatively undamaged. Fragmental quartz occur in the samples and is primary to later forming alteration minerals.Amphiboleis also considered to be primary, but can also been formed during regional metamorphism. Two lithologies could be identified in addition to the main protolith. Two samples were located above the marble horizon and was classified as basaltic unit with Ca-plagioclase, biotite and amphibole. One sample mainly consisted of aligned amphibole and biotite and is considered to be an amphibolite xenolith or a dyke intruding the main protolith rock. An increase in the alteration minerals albite, amphibole, epidote and allanite, with peak intensity found north-east of the mine site. This is confirmed by the geochemistry of major elements Fe2O3, MgO, CaO and the ratio between Na2O and K2O. The zonation is explained by a suggested increase in temperaturecondition during metamorphosis. This could be explained by either an underlying intrusion or bystructurally controlled variation in metamorphism by e.g. major faults running through the area.Comparisons with previous work in Björkdal favors an intrusion-related origin for the gold deposit.

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No. of bitstreams: 1 Carolina Gonçalves Leandro 2017 Dissertação.pdf: 10712768 bytes, checksum: ee554a9308600c58ba9930f1d2d302ae (MD5) Previous issue date: 2017 / A Mina Cerro Rico localiza-se aproximadamente a 7 km a leste da cidade de Lavras do Sul, na região central do estado do Rio Grande do Sul e está sob licença de pesquisa mineral da empresa Amarillo Mineração do Brasil Ltda. A área de pesquisa possui 15,758 km², delimitada pelas longitudes 53º 47’ 42,7” W - 53º 50’ 56,4” W e pelas latitudes 30º 48’ 5,7” S - 30º 49’ 46” S. A ocorrência mineral de Au, Ag e Cu desta área, está relacionada a presença de zonas de alteração hidrotermal caracterizadas por filões de quartzo de direções NW e EW, alojados nas rochas vulcânicas da Formação Hilário (~ 580 Ma). Os dados aerogeofísicos pertencem ao levantamento gamaespectrométrico – Projeto Lavras do Sul – Rio Grande do Sul, o qual foi executado no ano de 2007 pela empresa Prospectors Aerolevantamentos e Sistemas Ltda. A partir de setores identificados pela caracterização de anomalias geofísicas oriundas do processamento dos dados aerogamaespectrométricos onde foi definida uma área para levantamentos geofísicos terrestres em escala de detalhe, aproximadamente de 1: 3.000, com os métodos geoelétricos de Eletrorresistividade e de Polarização Induzida, utilizando as técnicas de Caminhamento Elétrico e de Sondagem Elétrica Vertical. Os dados aerogamaespectrométricos permitiram a partir da interpretação do mapa Ternário dos radioelementos (K (%), eU (ppm), eTh (ppm)), a identificação de cinco domínios radiométricos que sugerem a presença de diferentes litologias, em termos de possíveis variações na textura e na mineralogia das rochas e solos presentes na área. Os perfis gamaespectrométricos integrados com os dados geoelétricos possibilitaram a identificação de possíveis zonas de fraturas e/ou falhas, com provável percolação de fluído hidrotermal e/ou presença de mineralizações metálicas. O modelo geofísico-geológico 2D proposto para a área da Mina Cerro Rico, sugere que o topo do embasamento andesítico se encontra entre 20 a 30 metros de profundidade, caracterizado pela presença de um relevo irregular, afetado por fraturas e/ou falhas. Conforme a integração dos resultados oriundos dos dados de resistividade e da cargabilidade, definiu-se que patamares anômalos com valor de resistividade em torno de 200 Ohm.m e de cargabilidade em torno de 8 mV/V a 12 mV/V, estão associados a presença de zonas de fraturas com possível mineralização metálica. Os setores da área com presença de fraturas preenchidas por veios de quartzo e com provável mineralização, resultam em potenciais atrativos, para dar continuidade e orientar futuras pesquisas relacionadas a prospecção aurífera na Mina Cerro Rico. / The Cerro Rico Mine is located approximately 7 km east of the Lavras do Sul city, in the central region of the state of Rio Grande do Sul and is under mineral exploration license of the Amarillo Mineração do Brasil company. The research area is 15,758 km², delimited by longitudes 53º 47 '42.7 "W - 53º 50' 56.4" W and latitudes 30º 48 '5,7 "S - 30º 49' 46" S. The occurrence of gold, silver and cooper minerals in this area are related to the presence of hydrothermal alteration zones characterized by quartz filaments through NW and EW directions, intruded in the volcanic rocks of the Hilário Formation (~ 580 Ma). The aerogeophysical data belongs to the Lavras do Sul Gammaspectrometric Survey Project, which was executed by Prospectors Aerial Surveys and Systems in 2007. The sectors was identified by the characterization of geophysical anomalies through the processing of aerogamaespectrometric data, in this area the geophysical surveying was made on a scale of approximately 1: 3.000 and defined with the geoelectric methods of Eletroresistivity and Induced Polarization using the techniques of 2D Horizontal Profiling and Vertical Electrical Sounding. The aerogamaespectrometric data allowed the identification of five radiometric domains that suggests the presence of differents lithologies in terms of possible variations in the radioelements (K (%), eU (ppm), eTh (ppm)), texture and mineralogy of the rocks and soils present in the area. The gamma spectrometric profiles integrated with the geoelectric data allowed the identification of possible zones of fractures and/or faults, with probable percolation of hydrothermal fluid and/or presence of metallic mineralizations. The 2D geophysical-geological model proposed for the Cerro Rico Mine area, suggests that the depth of the top of the andesitic basement is between 20 and 30 meters, characterized by the presence of irregular relief, affected by fractures and/or faults. According to the integration of the results from the resistivity and chargeability data, the anomalous levels with a resistivity value around 200 Ohm.m and chargeability of 8 mV/V to 12 mV/V are associated with the presence of fracture zones with possible metallic mineralization. The sectors of the area with presence of fractures filled by quartz veins and probable mineralization, results in attractives potentials, to give continuity and guide future research related to gold prospecting in the Cerro Rico Mine.

Les roches vulcanogéniques de la Mine de Seival appartiennent à la Formation Hilário du Bassin de Camaquã, d’âge Néoprotérozoique. Ces roches contiennent six mines inactives avec diverses prospections de cuivre–argent. Les minéralisations semblent associées à un contrôle structurel intense du régime ruptile. La compréhension de la transformation chimique de l’hydrothermalisme associé aux paléo-contraintes est assez faible dans la région. Nous proposons de caractériser la chimie des minéraux des phases magmatiques, tardi–magmatiques et hydrothermales ainsi que de comprendre les contraintes structurales et la géochimie des veines tardives de barytine et calcite. Pour ce faire, nous avons effectué des analyses minéralogiques, et chimiques des phases magmatiques et d’altération. La chimie minérale associée à la modélisation thermodynamique a permis de caractériser l’altération comme tardi– magmatique. L’albitisation (650 à 350 °C) s’est produite en association avec une chloritisation (312 à 120 °C) et avec de la pyrite et de la chalcopyrite. Les températures les plus basses (150 à 50 °C) ont été reliées à la formation de smectite et d’inter-stratifié de chlorite/smectite et avec de la chalcocite–covellite, chalcocite–bornite ou barytine. Nous effectuons les analyses structurales des mesures de cinématique et de la direction des failles/fractures. L’analyse structurale a montré trois contraintes principales survenant dans la Mine Seival et dans le District Minier de Lavras do Sul : compression NW–SW ; compression NE–SW ; distension ENE–SWS. La contrainte NW–SE est la principale direction de contrainte associée à la minéralisation et aux filons minéralisés dans ces deux régions. / The volcanogenic rocks of the Seival Mine belong to Hilário Formation from Camaquã Basin, with ages Neoproterozoic. These rocks contain six inactive mines with various prospects of copper-silver. Mineralization are associated with intense structural control in brittle regime. Chemical transformation of hydrothermal alteration associated with paleostress is not very well understood in the region. We propose a characterization of mineral chemistry of the magmatic phases, tardi–magmatic and hydrothermal as well as understand the paleostress and geochemistry of late veins. For this, we realized analyses of mineral chemistry of magmatic and alteration phase. Mineral chemistry coupled with thermodynamic modeling allowed to characterize the alteration as tardi–magmatic. The albitization (650 to 350 °C) occurred in association with chloritization (312 to 120 °C), and with pyrite and chalcopyrite. The lowest temperatures (150 to 50 °C) were related to formation of smectite and interlayered chlorite/smectite, and with chalcocite–covellite, chalcocite–bornite or barite. We perform structural analyzes through kinematic measures and failure/fracture directions. The analysis on faults, fractures and mineralization showed three main stresses occurring in the Seival Mine and Lavras do Sul Mining District: NW–SE compression; NE–SW compression; ENE–SWS distension. The NW–SE paleostress is the main effort related to the dikes and mineralization in both areas.

This thesis study is concerned with the genetic investigation of two epithermal gold deposits (Madendag and Kartaldag) in &Ccedil / anakkale, NW Turkey. The methodology comprises field and integrated laboratory studies including mineralogic-petrographic, geochemical, isotopic, and fluid inclusion analysis. Kartaldag deposit, hosted by dacite porphyry, is a typical vein deposit associated with four main alteration types: i) propylitic, ii) quartz-kaolin, iii) quartz-alunitepyrophyllite, iv) silicification, the latter being characterized by two distinct quartz generations as early (vuggy) and late (banded, colloform). Primary sulfide minerals are pyrite, covellite and sphalerite. Oxygen and sulfur isotope analyses, performed on quartz (&delta / 18O: 7.93- 8.95 &permil / ) and pyrite (&delta / 34S: -4.8 &permil / ) separates, suggest a magmatic source for the fluid. Microthermometric analysis performed on quartz yield a temperature range of 250-285 &ordm / C, and 0-1.7 wt % NaCl eqv. salinity. Madendag deposit, hosted by micaschists, is also vein type associated with two main alteration types: illite and kaolin dominated argillization and silicification, characterized by two distinct quartz phases as early and late. Oxygen isotope analyses on quartz (&delta / 18O: 9.55-18.19 &permil / ) indicate contribution from a metamorphic source. Microthermometric analysis on quartz yield a temperature range of 235-255 &ordm / C and 0.0-0.7 wt % NaCl eqv. salinity. The presence of alunite, pyrophyllite and kaolinite, vuggy quartz and covellite suggest a high-sulfidation epithermal system for Kartaldag. On the other hand, Madendag is identified as a low- sulfidation type owing to the presence of neutral pH clays and typical low temperature textures (e.g. colloform, comb, banded quartz).

Les principales cibles d'exploration pour les gisements d’uranium de type discordance du bassin d’Athabasca (Canada) sont les structures graphiteuses du socle. Toutes ces structures ne sont pourtant pas fertiles et elles présentent des histoires plus ou moins complexes de circulations fluides successives. Cette thèse propose de déconvoluer les caractéristiques propres à chaque évènement de circulations fluides par une étude multidisciplinaire focalisée sur l’exemple de l’environnement proche du gisement de Cigar Lake. Au cours de l’exhumation tardi-orogénique du socle, la formation de failles ductile-cassantes associées à une circulation intense de fluides à C-O-H-N a permis des enrichissements en graphite et une première évolution pétrophysique des zones endommagées. Ces structures du socle particulièrement fragilisées par la déformation cassante fini-Hudsonienne ont pu être réactivées après dépôt du bassin et devenir des lieux favorables à la convection de saumures sédimentaires. La circulation de saumures sodiques dans le socle a favorisé des interactions fluides-roches à l’origine de la solubilisation de l’uranium, d’altérations K-Mg et d’évolution de composition du fluide vers un pôle plus calcique de plus forte salinité. Enfin une méthodologie d’analyse intégrée des compositions élémentaires majeures, traces et isotopiques U-Pb-O sur oxydes d’uranium est proposée, permettant de déconvoluer les effets des évènements fluides ultérieurs sur la minéralisation primaire. Cinq évènements ont ainsi contribué aux caractéristiques actuelles du gisement de Cigar Lake : Un évènement primaire de circulation de saumures à 1290-1380 Ma, à l’origine de l’ensemble du stock d’uranium ; un événement de circulations fluides à ca. 900 Ma à l’échelle régionale qui n’est pas associé à une reprécipitation d’uranium mais a brechifié et perturbé la chimie des oxydes primaires ; deux évènements tardifs de circulations fluides à ca. 340 et 220 Ma qui ont significativement remobilisé le stock primaire d’uranium. Enfin un dernier épisode récent de circulation d’eaux météoriques est à nouveau à l’origine d’un changement de chimie des oxydes antérieurs et d’une remise à zéro des systèmes isotopiques / The main exploration targets for unconformity-related U deposits of the Athabasca Basin are the graphite-rich structures in the basement. But these are not necessarily fertile. They show distinct features expressing specific events of fluid circulations. This study aims, through a multidisciplinary approach, at unravelling the complex history of fluid flow events recorded in the vicinity of the Cigar Lake deposit. During the basement uplift, at the end of the Trans-Hudson Orogeny, the formation of ductile-brittle shear zones associated to the circulation of C-O-H-N fluids led to hydrothermal graphite enrichments and a petrophysical evolution of damages zones. These graphite-rich shear zones that were specifically weakened by the ante-Athabasca brittle reactivation have been reactivated once more after basin deposition allowing the formation of a developed damage zone especially favorable for sedimentary brine convection. Circulations of NaCl-rich brines in the basement led to brine-rock interactions, and subsequent uptake of uranium and other metals from the basement rocks. The latter have subsequently undergone strong K-Mg alteration whereas the NaCl dominated brines evolved toward a CaCl2-dominated composition with higher salinities. Finally, this thesis sets out an integrated methodology allowing to decipher the complex superimposed geochemical signatures of distinct fluid flow events on the primary uranium oxides. Five fluid flow events contributed to the present day state of the Cigar Lake deposit: a primary event of brine circulation occurred at 1290-1380 Ma and is at the origin of the main U stock; a second basin-scale event of fluid flow occurred at ca. 900 Ma, it brecciated and strongly disturbed the deposit; two later events of fluid flow strongly remobilized the deposit at ca. 340 and 220 Ma and greatly contributed to the actual state of the deposit. Finally a last, rather recent event of fluid flow was at the origin of strong chemical changes in the uranium oxides compositions and strong isotopic resetting

Orientadores: Roberto Perez Xavier, Carlos Roberto de Souza Filho, Lena Virginia Soares Monteiro / Tese (doutorado) -Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-12T19:03:21Z (GMT). No. of bitstreams: 1 Carvalho_EmersondeResende_D.pdf: 11938678 bytes, checksum: fdc3794a3948e2508d41b33690dcf01d (MD5) Previous issue date: 2009 / Resumo: O depósito de óxido de ferro-cobre-ouro de Sossego na Província Mineral de Carajás (PMC), região norte do Brasil, consiste de três corpos de minério principais, denominados Sossego-Curral, Sequeirinho-Baiano e Pista, envolvidos por zonas de alteração hidrotermal sódica, sódico-cálcica, potássica, clorítica e hidrolítica. Essas zonas de alteração hidrotermal mostram diferentes graus de desenvolvimento em cada corpo de minério. Os estágios iniciais de alteração foram controlados pelo fluxo de fluido em zonas de cisalhamento regionais, enquanto a mineralização cupro-aurífera corresponde a uma fase tardia e se formou em um ambiente estrutural rúptil. Salmouras hipersalinas, quentes (> 500 oC) e compostas essencialmente por NaCl-CaCl2-H2O podem estar associadas com o desenvolvimento inicial do sistema hidrotermal Sossego. As brechas sulfetadas Sequeirinho e Sossego mostram um enriquecimento em Cu-Fe-Au-(Ag)- Ni-Co-Se-Y-V-P-La-Ce e baixo conteúdo de Ti, semelhante a outros depósitos de óxido de Fe-Cu-Au em Carajás e em termos mundiais. O alto conteúdo de Ni, Co, Se, V e Pd, especialmente no corpo Sequeirinho, possivelmente é decorrente da lixiviação de metais a partir de fontes como o gabro, que tem relação espacial com os corpos de magnetitito e as zonas mineralizadas, e lente de rochas metaultramáficas do Supergrupo Itacaiúnas. Os processos de interação fluido-rocha devem ter resultado em significativa lixiviação de metais da seqüência de rochas hospedeiras, que foi acentuado por fluidos hidrotermais inicialmente de alta temperatura (>500 oC) e alto conteúdo de cloreto no sistema hidrotermal Sossego, movido pelo calor dos vários episódios de intrusões registrados na PMC. As inclusões fluidas de amostras dos estágios finais da evolução do sistema hidrotermal Sossego, indicam a participação de (1) salmouras hipersalinas; (2) salmouras salinas, de baixa temperatura (~150 oC) e ricos em CaCl2; e (3) fluidos de baixa salinidade e baixa temperatura (< 250 oC) e compostos por NaCl-H2O, representativos, respectivamente dos estágios inicial, principal e final da mineralização de Cu-Au. As salmouras salinas ricas em CaCl2 poderiam refletir uma evolução contínua a partir de um fluido hipersalino magmático ou envolver fluidos bacinais de baixa temperatura, incluindo um componente derivado de evaporitos. Os fluidos portadores de NaCl e de baixa salinidade predominam nos estágios finais do evento mineralizante e podem representar o influxo de fluidos meteóricos. A transição para um regime estrutural dominantemente rúptil e o resfriamento do sistema favorecem o influxo desses fluidos meteóricos oxidados. A mistura de fluidos pode ter sido o mecanismo principal que desencadeou a precipitação da maior parte do Cu e Au nos diferentes corpos de minério do depósito de Sossego. / Abstract: The Sossego iron oxide-copper-gold deposit in the Carajás Mineral Province (CMP), northern Brazil, consists of three main orebodies, named Sossego-Curral, Sequeirinho-Baiano and Pista, enveloped by sodic, sodic-calcic, potassic, chloritic, and hydrolithic hydrothermal alteration zones. These alteration zones display different degrees of development in these orebodies. The early alteration stages were controlled by fluid-flow in large-scale regional shear zones, whereas bulk copper-gold mineralization was late and formed in a brittle structural environment. Hypersaline NaCl-CaCl2-H2O hot (>500 oC) brines could be associated with the initial development of the hydrothermal system. Sequeirinho and Sossego sulfide ore breccias are marked by enrichment in Cu-Fe-Au-(Ag)-Ni-Co-Se-Y-V-P-La-Ce and low contents of Ti, which also occur in other IOCG deposits of CMP and worldwide IOCG deposits. The high contents of Ni, Co, Se, V and Pd, particularly in Sequeirinho orebody, possibly were originated by metal leaching from sources such as intrusive gabbro, which have spatial relationship with massive magnetite bodies and mineralized zones, and metaultramafic lenses of Itacaiúnas Supergroup. Fluid-rock interaction process might have resulted in significant metal leaching from host sequences, enhanced by early high temperature (>500 oC) and high chloride concentrations of hydrothermal fluids in the extensive Sossego hydrothermal system driven by heat from several intrusive episodes recorded in the CMP. Fluid inclusions of the samples from the final stages of evolution of the Sossego hydrothermal system in brittle conditions, indicated participation of hot hypersaline brines, low temperature (~150 oC) CaCl2-rich saline brines and low-temperature (<250 oC) low salinity NaCl-H2O fluids in early, main and late mineralization stages. The CaCl2-rich saline brines could reflect continuum evolution from magmatic hypersaline fluids or involve low temperature basinal, including evaporite-derived fluids. Low salinity, NaCl-bearing fluids, predominates in late stages and reflect channelized influx of meteoric fluids. The transition to a dominantly brittle structural regime and cooling of the system favors the influx of these oxidized meteoric-derived fluids. Fluid mixing could have represented a major influence on ore precipitation in different orebodies from the Sossego IOCG deposit and could have had fundamental importance to trigger the bulk of copper deposition. / Doutorado / Metalogenese / Doutor em Ciências

Orientadores: Alvaro Penteado Crosta, Jorge Enrique Coniglio, Carlos Roberto de Souza Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-09T01:02:20Z (GMT). No. of bitstreams: 1 Ducart_DiegoFernando_D.pdf: 12616114 bytes, checksum: 269fcd23fc0d54b276f58844eebbd62f (MD5) Previous issue date: 2007 / Resumo: O prospecto epitermal Cerro La Mina, localizado na região de Los Menucos, Patagônia Argentina, está sendo atualmente alvo de exploração de depósitos epitermais de metais preciosos. Atividade hidrotermal Triássica Superior produziu intensa alteração em riolitos, andesitos, ignimbritos e tufos do Grupo Los Menucos de idade Triássico Média a Superior, no maciço de Somún Curá. O emprego de técnicas de mapeamento geológico, sensoriamento remoto multi- e hiperespectral, espectroscopia de reflectância e de análise de isótopos estáveis permitiu a caracterização de cinco eventos de alteração de origem hidrotermal na área de estudo. O evento 1 resultou em um sistema epitermal de baixa sulfetação com veios de quartzo, alguns deles com ocorrências de ouro com teores entre 1 a 10 g/t e alteração sericítica, que afetou ignimbritos riolíticos e rochas sedimentares da Formação Vera. As alterações relacionadas aos eventos 2 e 3, as mais importantes do ponto de vista volumétrico, se relacionam a um sistema epitermal de alta sulfetação, afetando riolitos, dacitos e andesitos da Formação Sierra Colorada. Estas rochas vulcânicas constituem um complexo de domos de ressurgimento, localizado no interior de uma provável caldeira vulcânica de forma oval, vinculada a uma zona transtensiva entre duas falhas transcorrentes destrais regionais. Algumas das características mais importantes deste sistema epitermal incluem a presença de brechas hidrotermais, algumas com ocorrências de ouro com teores muito locais de até 60 g/t, silicificação pervasiva e quartzo vuggy, junto com alteração argílica avançada com alunita- 1 hipogênica, woodhouseita, svanbergita, minamiita, pirofilita, diásporo, dickita e caulinita. A alunita-l formou-se a 267°C, indicando uma origem hidrotermal-magmática. Valores de d 'POT. 34¿S da alunita-l (4,4 a 10,3 %0) são maiores do que os obtidos para a pirita contemporânea (-14,8 a -10,8%0) sugerindo que o sulfato aquoso foi derivado da reação de desproporção do S 'O IND. 2¿ em um ambiente hidrotermal-magmático. Os valores de d 'POT. 34¿S e d 'POT. 18¿ O da alunita-1 sugerem que o vapor que transportava o S 'O IND. 2¿ condensou em água meteórica com uma razão 'H IND. 2¿ S/¿SO IND.4¿ <1. Os valores isotópicos de oxigênio e hidrogênio da caulinita e dickita também são compatíveis com uma origem hidrotermal-magmática. A alteração relacionada ao evento 4, de forma estratiforme horizontal e caracterizada por intensa silicificação com calcedônia e opala, gradando localmente em profundidade para alteração argílica avançada com alunita-2 mais caulinita ± dickita, foi originada em um ambiente steam-heated. A alunita-2 está enriquecida em 'S SOB. 34' relativamente ao sulfeto, refletindo troca isotópica parcial de enxofre entre os componentes aquosos 'H IND. 2¿ S e ¿SO IND.4¿. Esta alteração se superpõe localmente às alterações dos eventos 2 e 3, sugerindo uma queda do nível do lençol freático, provavelmente somado à denudação sin-hidrotermal da parte superior das rochas. O evento 5 está metalogeneticamente relacionado com a formação de depósitos de fluorita, comparáveis de forma descritiva aos mundialmente conhecidos como "veios de fluorita-quartzo de baixa temperatura". Estas mineralizações de fluorita não estariam vinculadas com os processos metalogenéticos relacionados às mineralizações de ouro dos sistemas epitermais do prospecto. Os resultados deste estudo contribuem significativamente no entendimento de aspectos relacionados à gênese deste sistema epitermal complexo, constituindo parâmetros importantes para a formulação de um modelo de exploração mineral para a região. Uma consistente discriminação de minerais de alteração deste prospecto foi também conseguida por meio de sensoriamento remoto orbital. A aplicação de técnicas de processamento em imagens dos sensores multiespectral Terra/ASTER e hiperespectral Hyperion resultou em diferentes mapas litológicos, minerais e estruturais. A correlação satisfatória entre estes resultados e dados de campo demonstra a importância do sensoriamento remoto nos trabalhos de um programa de exploração, tanto para as etapas iniciais em escala regional, como também para etapas mais avançadas em escala de prospecto ou de depósito / Abstract: The epithermal Cerro La Mina prospect, located in the Los Menucos region, Patagonia Argentina, is currently being explored for epithermal precious-metal mineralization. Triassic hydrothermal activity produced intense alteration of rhyolites, andesites, ignimbrites, and tuffs of the Middle- to Late Triassic Los Menucos Group, in the Somún Curá massif. The use of techniques, including geological mapping, multi- and hyperspectral remote sensing, reflectance spectroscopy and staple isotope analysis, alIowed the characterization of five hydrothermal alteration stages in the study area. Event 1 resulted in a low-sulfidation epithermal system with quartz veins, some of them with gold grades between I and 10 g/t and sericitic alteration, which affected riolitic ignimbrites and sedimentary rocks of the Vera Formation. Alteration associated to stages 2 and 3, the most important from the volumetric viewpoint, is related to a high-sulfidation alteration system, which affected rhyolites, dacites and andesites of the Sierra Colorada Formation. These volcanic rocks comprise a complex of resurgent domes, located within a likely oval-shaped volcanic caldera, formed in a transtensive zone placed between two regional dextral strike-slip faults. Some of the most important characteristics of this epithermal system include the presence of hydrothermal breccias, some with gold occurrences with grades locally reaching up to 60 g/t, pervasive silicification and vuggy quartz, together with advanced argillic alteration with hypogenic alunite-l, woodhouseite, svanbergite, minamiite, pyrophyllite, diaspore, dickite and kaolinite. Alunite-l was formed at 267°C, indicating a hydrothermal-magmatic origino Values of d 'POT. 34¿S of alunite-l (4.4 to 10.3 %0) are higher than those obtained for contemporary pyrite (-14.8 to -10.8%0), suggestirig that aqueous sulfate was derived of the S 'O IND. 2¿ disproportion reaction in a hydrothermal-magmatic system. d 'POT. 34¿S and d 'POT. 18¿ O values from alunite-l suggest that the vapor that carried S 'O IND. 2¿ condensate in meteoric water with a ratio of 'H IND. 2¿ S/¿SO IND.4¿ <1. Isotopic values of oxygen and hydrogen for kaolinite and dickite are ais o compatible with a hydrothermal-magmatic origino Alteration related to event 4, characterized by intense silicification blanket with chalcedony and opal, locally grading at depth to advanced argillic alteration with alunite-2 plus kaolinite ± dickite, was originated in a steam-heated environrnent. Alunite-2 is enriched in 'S SOB. 34' in relation to sulfide, reflecting a partial isotopic exchange of sulfur between the aqueous components 'H IND. 2¿ S e ¿SO IND.4¿. This alteration localIy overprints those from stages 2 and 3, suggesting a fall in the level of the water table, probably adding up to syn-hydrothermal erosion of the upper portion of the rocks. Event 5 is related to the formation of fluorite veins, comparable to low-temperature quartz-fluorite veins. These fluorite mineralizations are apparently not linked with the processes related to the gold epithermal. systems of the prospect. The results of this study contribute significantly in the understanding of metallogenic aspects of this complex epithermal system, constituting important parameters to the formulation of a mineral exploration model for the region. Consistent discrimination of the main alteration minerais of this prospect was also achieved by means of satellite remote sensing. The application of processing techniques on images of the multispectral- Terra/ASTER and hyperspectral Hyperion sensors resulted in different lithologic, mineral and structural maps. Satisfactory correlations between these results and field data demonstrate the key importance of the remote sensing in the work of an exploration program, in the initial stages of regional scale and also in more advanced stages, at prospect or deposit scales / Doutorado / Metalogenese / Doutor em Ciências