Dissertations / Theses on the topic 'Cu mineralisation'

Continental red bed sequences are host, on a worldwide scale, to a characteristic style of mineralisation which is dominated by copper, lead, zinc, uranium and vanadium. This study examines the features of sediment-hosted ore deposits in the Permo-Triassic basins of Western Europe, with particular reference to the Cu-Pb-Zn-Ba mineralisation in the Cheshire Basin, northwest England, the Pb-Ba-F deposits of the Inner Moray Firth Basin, northeast Scotland, and the Pb-rich deposits of the Eifel and Oberpfalz regions, West Germany. The deposits occur primarily but not exclusively in fluvial and aeolian sandstones on the margins of deep, avolcanic sedimentary basins containing red beds, evaporites and occasionally hydrocarbons. The host sediments range in age from Permian to Rhaetian and often contain (or can be inferred to have originally contained) organic matter. Textural studies have shown that early diagenetic quartz overgrowths precede the main episode of sulphide deposition. Fluid inclusion and sulphur isotope data have significantly constrained the genetic hypotheses for the mineralisation and a model involving the expulsion of diagenetic fluids and basinal brines up the faulted margins of sedimentary basins is favoured. Consideration of the development of these sedimentary basins suggests that ore emplacement occurred during the tectonic stage of basin evolution or during basin inversion in the Tertiary. 34S values for barite in the Cheshire Basin range from 13.8% to 19.3% and support the theory that the Upper Triassic evaporites were the principal sulphur source for the mineralisation and provided the means by which mineralising fluids became saline. In contrast, 34S values for barite in the Inner Moray Firth Basin (mean 34S = + 29%) are not consistent with simple derivation of sulphur from the evaporite horizons in the basin and it is likely that sulphur-rich Jurassic shales supplied the sulphur for the mineralisation at Elgin. Possible sources of sulphur for the mineralisation in West Germany include hydrothermal vein sulphides in the underlying Devonian sediments and evaporites in the overlying Muschelkalk. Textural studies of the deeply buried sandstones in the Cheshire Basin reveal widespread dissolution and replacement of detrital phases and support the theory that red bed diagenetic processes are responsible for the release of metals into pore fluids. The ore solutions are envisaged as being warm (60-150%C), saline (9-22 wt % equiv NaCl) fluids in which metals were transported as chloride complexes. The distribution of 34S values for sulphides in the Cheshire Basin (-1.8% to + 16%), the Moray Firth Basin (-4.8% to + 27%) and the German Permo-Triassic Basins (-22.2% to -12.2%) preclude a magmatic source for the sulphides and support the contention that sulphide precipitation is thought to result principally from sulphate reduction processes, although a decrease in temperature of the ore fluid or reaction with carbonates may also be important. Methane is invoked as the principal reducing agent in the Cheshire Basin, whilst terrestrial organic debris and bacterial reduction processes are thought to have played a major part in the genesis of the German ore deposits.

The Palaeoproterozoic Johan Petersen Intrusive Centre (JPIC) formed as a continental arc at the North Atlantic Craton margin during the formation of the ca. 1.9 Ga Nagssugtoqidian Orogen (NO) in SE Greenland. Magmatic Ni-Cu deposits in the coeval Trans-Hudson and Svecofennian Orogens (THO and SFO) make the NO the primary target for Ni-Cu deposits in Greenland. Using mapping, petrography, geochemistry, and multiple sulphur isotope geochemistry, this thesis deals with the formation of the JPIC and related mineralisation, and compares it with previously discovered Ni-Cu mineralisation in the NO and Trans-Hudson and Svecofennian Orogens. The JPIC formed from an early series of dioritic to granitic magmas intruding into paragneiss under granulite facies conditions. A mafic series of gabbroic rocks intruded into both the paragneiss and the earlier felsic series rocks. Late mafic-ultramafic sheets and magmatic breccias intruded predominantly into the mafic series rocks. Two episodes of intrusion by mafic-ultramafic stringers happened when the felsic and mafic series rocks were semi-solid. Late granite likely formed from back-veining of residual melts. Uplift during orogenesis caused retrograde amphibolite facies metamorphism, and late hydrothermal alteration of both intrusive rocks and their mineralisation took place under temperature conditions corresponding to amphibolite- to mid greenschist facies. The mineralised rocks in the JPIC occur as contact mineralisation between the intrusive rocks and the adjacent paragneiss, as mineralisation in the stringers mingling with the mafic series rocks, and as accumulated sulphide liquids in the later sheets and breccias. In the contact style mineralisation, sulphides are disseminated, network-like or semi- massive and show S isotopic compositions indicating a Palaeoproterozoic sedimentary sulphur source. Ni and Cu contents in the sulphide phase are low. Sulphides in the mineralised stringers and mafic-ultramafic sheets and breccias are disseminated to network-like, and have mantle-like isotopic compositions of sulphur. The ultramafic sheets and breccias have higher Ni-Cu contents and tenors and currently form the primary targets. The JPIC mineralisation is similar to that in the Kotalahti-Vammala belt of the SFO, and although sub-economic at the moment, possible existence of deeper-seated sulphides would give the area an upside potential for more discoveries.

The Kansanshi Cu-Au deposit located in the Domes region of the North West province of Zambia is characterised by structurally controlled high angle veins and associated alteration halos. The northwest trending Kansanshi antiform flanks the Solwezi syncline to the north and hosts the Kansanshi deposit and consists of tillites and metasedimentary rocks. Mineralisation is associated with Neoproterozoic Pan African deformation events experienced during the formation of the Lufilian fold belt; however recent findings confirm that structures in the form of reverse and normal faults and drag folds are critical controls on mineralisation within the deposit, Main pit in particular. Low angle faults occurring below the current pit are believed to have served as major fluid pathways during mineralisation. Age dating data from the Kansanshi deposit suggest that mineralisation took place between 512 and 503 Ma indicating that the event was associated with metamorphism. Two types of alteration are dominant within the Main pit (Kansanshi deposit) with the type and intensity of alteration being largely controlled by lithological units. Albite alteration occurs dominantly in phyllites and schists whereas dolomitisation is prevalent in calcareous units. Alteration is associated with mineralisation, and therefore is used as a condition for predicting vein or disseminated mineralisation. The high Au tenor at Kansanshi can be attributed to gold grains occurring in association with melonite (NiTe₂) and microfractured pyrite intergrown with chalcopyrite in sulphide and quartz dominated veins and veinlets. Analysis of gold grade distribution within the Main pit shows a clear concentration of the element along the major north-south trending structures like the 4800 and 5400 zones, possibly through supergene enrichment in the oxide-transition-sulphide zones. It is imperative that exploration for Kansanshi-type deposits will require geochemical and geophysical studies, understanding of the geology of an area to identify the three lithostratigraphic units (red beds, evaporites and reducing strata).

The Caledonian mafic and ultramafic intrusions of the Grampian region of N.E. Scotland are a suite of synorogenic tholeiitic plutons of mid-Ordovician Age. They include layered cumulates, granular gabbronorites, quartz biotite norites and xenolithic contact facies lithologies. They postdate two regional deformation events in the enclosing Late Precambrian Dalradian metasediments, but are themselves locally deformed by a major regional ductile shear zone system. A detailed study of the Huntly-Knock area was undertaken combining geological mapping, petrological, geochemical and stable isotope techniques. In the study area, layered peridotitic to gabbroic cumulates, transitional cumulate types, granular gabbronorites quartz biotite norites and complex xenolithic contact facies rock types are present as a series of disrupted bodies formed by multiple intrusive events and subsequent deformation of a laccolithic and sheeted intrusive complex. Progressive cryptic fractionation trends are observed from basal peridotites to quartz biotite norites in the 'roof' of the intrusion. The chemistry and mineralogy of the rocks places them in the Lower and Middle Zone of the regional Younger Basic 'stratigraphy', although isolated pockets of Upper Zone may occur. Fine grained disseminated Fe-Ni-Cu sulphides are widespread throughout the mafic and ultramafic rock types. Richer sulphide concentrations locally occur as: gabbronorite hosted disseminated to massive bodies in the structurally complex, Littlemill-Auchencrieve contact zone; disseminated horizons within cumulates; disseminated to submassive graphite-rich pods in pyroxenitic pegmatites. The sulphide assemblage is dominated by pyrrhotite with minor pentlandite and chalcopyrite. Sulphide textures are attributed to magmatic processes with local modification by ductile deformation and hydrothermal reworking. Field, textural and Cu/Cu+Ni relations of certain submassive-massive sulphides is consistent with their derivation from an ultramafic parent. Maximum Ni and Cu levels are 3.02% and 6.46% respectively. The highest combined Pt+Pd+Au values occur in remobilised net sulphide (574ppb) and graphitic pyroxenite (700ppb). These metal values are generally low and comparable to other orogenic Caledonian intrusions. Sulphide immiscibility occurred many times during cooling of the tholeiitic parent magma(s), however early sulphide melts are generally of most economic importance. While there is abundant evidence for magma/country rock interaction, only locally is there evidence for involvement of metasediment sulphur, the system being dominated by a magmatic signature. In the Littlemill-Auchencrieve contact zone, crustal involvement may have been the principal factor controlling sulphide immiscibility. Subsequent hydrothermal reworking within ductile shear zones under amphibolite facies metamorphic conditions modified metal values. Depletion, especially of Au, Pt and Pd was mainly observed but local significant zones of enrichment may also be present.

This thesis investigates the tectonic and magmatic setting of a Copper-rich seafloor massive sulfide deposit. Integrated multi-scale data analysis produced a regional to deposit-scale framework to constrain how, why and where these types of mineral deposits form. Outcomes from this research advance our understanding of 1) regional tectonic evolution of the East Manus Basin, and 2) volcanic and magmatic processes conducive to seafloor massive sulfide deposit formation.

A temporal and spatial relationship between plume magmatism, cratonic lithosphere and the occurrences of orthomagmatic Ni-Cu and platinum-group element (PGE) sulphide mineralisation has been documented in the literature. However the underlying causes for this correlation have yet to be resolved – is there an inherent feature of the cratonic lithosphere and its mantle ‘keel’ that controls mineralisation? Or is this correlation purely a preservational bias in the geological record? Scotland has experienced multiple tectono-magmatic events and provides an ideal testing ground, or ‘framework’, in which to assess the role of lithospheric mantle on chalcophile element (Ni and Cu) and precious metal (PGE and Au) abundances through time. Given the well-documented geological history of the region (including several suites of mantle xenoliths), coupled with exploration campaigns in Greenland (with which Scotland has comparable geology), this thesis aims to assess the contributions and influences of lithospheric mantle vs. asthenospheric mantle during melting and mineralisation. It also evaluates the Ni-Cu-PGE mineralisation potential for Scotland, particularly in a Noril’sk-type conduit-hosted setting within the British Palaeogene Igneous Province (BPIP). The earliest major tectono-magmatic event following cratonisation of the North Atlantic Craton (NAC) occurred c. 2.4 Ga during Palaeoproterozoic extension, forming the maficultramafic Scourie Dyke Swarm. Despite evidence for lithospheric mantle melting at this time, the subcontinental lithospheric mantle (SCLM) below the Scottish portion of the NAC did not become severely depleted in sulphides or PGE. Instead, spinel lherzolite mantle xenoliths from this region (e.g., Loch Roag) record an influx of carbonatite-associated sulphides at this time, enriched in PGE, and providing a deeper indication of continental extension that may be correlated to carbonatitic intrusions in Greenland. Subsequent collision and orogenesis of the NAC in the late Palaeoproterozoic (c. 1.9 to 1.7 Ga) represents a second significant tectonomagmatic event, recorded in the Scottish SCLM as sulphide (re-)melting and formation of discrete Pt-sulphide minerals (cooperite). Hence the lithospheric mantle here became appreciably enriched in precious metals during the Palaeoproterozoic, but crucially this preserved multiple co-existing populations of sulphides, distinct in their petrographic setting and geochemistry. Cratonic basement and associated mantle lithosphere are absent in the southern terranes of Scotland. This provides a direct comparison between lithospheric mantle geochemistry for Archaean-Palaeoproterozoic terranes north of the Great Glen Fault vs. Palaeozoic terranes south of the Great Glen Fault. Rifting of Rodinia and opening of the Iapetus Ocean in the late Neoproterozoic thus marks a significant change in geodynamic setting. This is especially apparent in the concentration of cobalt in lithospheric mantle sulphides, which appears to be inherently linked with the formation and/or later destruction (subduction) of oceanic crust during the Grampian event of the Caledonian orogeny. The impingement of the proto-Icelandic mantle plume initiated in the Palaeogene at the base of the NAC lithospheric mantle keel of Scotland and Greenland. The earliest Palaeogene magmas are enriched in Pt (i.e., have a high Pt/Pd ratio), whilst subsequent magmas associated with the opening of the Atlantic Ocean have successively lower Pt/Pd ratios. High Pt/Pd ratios are therefore coincident with magmas that have intruded through cratonic lithosphere. The SCLM at the margin of this region is known to be Pt-enriched (with cooperite) and therefore the changing Pt/Pd ratio of North Atlantic Igneous Province magmas suggests a fundamental interaction between the mantle plume and pre-enriched SCLM. Thus, whilst the concentration of metals, particularly Ni and Cu, is largely based on the high degree of asthenospheric mantle melting associated with the plume itself, the ratio of precious metals, such as Pt/Pd, can be strongly influenced by SCLM geochemistry. Overall, the intricate subtleties of metasomatic signatures recorded by mantle xenolith sulphides (or populations of sulphides) could allow for metallogenic ‘mapping’ of the upper mantle. This may identify areas of geochemical and mineralogical ‘preconditioning’, and together with geophysical constraints such as major lithospheric lineaments, it may be possible to establish the craton-specific fertility of a region. Finally, in order for orthomagmatic sulphide mineralisation to occur, magmas must achieve sulphur saturation in the upper crust, forming an immiscible sulphide liquid and thereby collecting PGE and chalcophile elements, possibly to economic grades. Thus a crucial part of assessing the mineralisation potential of a region must entail an investigation into the causes and locations of S-saturation. Given that crustal sulphur contamination is a common trigger for magmatic S-saturation, this thesis establishes the first S-isotopic (δ34S) framework for western Scotland in order to identify areas of sulphur contamination in the BPIP. In Scotland, the most readily available and S-rich rocks occur in the Mesozoic Hebrides Basin. Sulphur contamination of BPIP rocks is widespread and both S-saturation and S-undersaturation can be observed, suggesting that the region may be extremely fertile for orthomagmatic Ni-Cu-PGE mineralisation. By reconstructing the Hebrides Basin stratigraphy we can assess locations of contamination, even if these are above the current level of exposure (and since removed by erosion), and in some situations sulphide liquid sinking may be demonstrated, suggesting further possibilities for mineralisation present ‘up-stream’ in magmatic conduits. In conclusion, the Scottish BPIP represents a new exploration frontier not yet identified by industry for orthomagmatic Ni-Cu-PGE mineralisation. The conclusions are based on approximately 500 rock samples from across Scotland, which have been analysed for major elements and over thirty trace elements (including PGE) and S-isotopes. All data are available on an accompanying CD.

The genesis of the Minto copper-gold deposit, YT, Canada, has been variously interpreted since its discovery although no existing model accounts for ductile deformation as a control on mineralization. Results from this study show that Minto ore is hosted within ductiley deformed granitoid host rocks emplaced as multiple intrusions into an actively deforming environment, with the variably sheared host rocks separated by incipiently deformed granodiorites essentially barren of mineralisation. Contacts between deformed/mineralized rock and incipiently deformed/barren rock range from abrupt to gradational, and are the product of pre-existing igneous contacts, variably partitioned deformation, or a combination of these. Deformation of granitoids is interpreted to have controlled fluid flow, with associated alteration promoting further deformation and fluid flow. Potassic alteration, in the form of biotite-magnetite, is the dominant alteration associated with mineralisation, and analysis of alteration using isocon diagrams indicates that K, Fe, Si, Cu, Au, and Ag have been added during alteration, although mass has been lost overall due to a relative reduction in Na and Ca. Host rock intrusion, mineralization, and deformation are interpreted via geochronology and crosscutting relationships as ongoing over at least 5 m.a., from about 202 Ma until about 197 Ma, based on U-Pb SHRIMP geochronology of zircons in granitoids and Re-Os ICP-MS geochronology of molybdenite. The trend of mineralisation is now coincident with the strike of foliation on short steep limbs and of axial planes of folded foliation. This geometry may not be representative of original processes, but of remobilization of ore during continued deformation. The above observations, coupled with data from existing studies, strongly suggest Minto is representative of deposit generation within an arc subduction environment at depths not typically considered for copper-gold deposit formation.

The Masumbi Au-Cu deposit in the Ndori Greenstone Belt of western Kenya is hosted in dacitic volcanics of the Nyanzian Group (2710 ± 340 Ma) and dioritic to granodioritic felsic intrusives (2504 ± 48 Ma). The deposit is characterised by gold and copper mineralisation that is associated with quartz-sulphide veins and veinlets. The copper mineralisation typically occurs as chalcopyrite. Gold is closely associated with pyrite in mineralogy and its pathfinder elements silver, bismuth, tellurium and selenium in geochemistry. The gold occurs in two forms that may indicate two generations of precipitation: the equant and the elongate forms. Based on Au/Ag ratios, the equant gold grains can be classified as native gold as their gold content is greater than 90 wt%. The elongate gold grains can be classified as electrums as their silver content is greater than 38 wt%. While there is a strong Au-Ag association within individual gold grains supporting an orogenic model for the gold mineralisation, mineralisation at the Masumbi Prospect appears atypical of Archaean orogenic gold deposits because of the abundance of copper (up to 0.43%). The enrichment of silver, copper, bismuth and tellurium in ore assemblages is common in porphyry, VMS and epithermal systems, but their presence at Masumbi does not preclude the formation as an orogenic deposit. Assay results from three Masumbi diamond drill-holes show an apparent correlation between gold and copper. However, petrography and electron probe microanalyses results from this study indicate that chalcopyrite is an earlier phase than pyrite as it occasionally occurs as inclusions in pyrite. This petrogenetic relationship between pyrite and chalcopyrite suggests that there is no temporal relationship between gold and copper mineralisation. Statistical analysis of the assays shows no linear correlation between gold and copper thereby supporting the above findings. The gold and copper mineralisation have been interpreted as forming as two separate events with copper forming first followed by gold. These events are both related to the intrusion of the felsic rocks that are associated with the Aruan metamorphic event that has been responsible for the bulk of the gold mineralisation on the Tanzanian Craton. The common alteration assemblage in the Masumbi rocks comprises chlorite and epidote. This alteration assemblage is typical of regional greenschist metamorphic facies grading into amphibolite metamorphic facies in the Nyanzian Group of Kenya. However, these alteration minerals could possibly be products of propylitic alteration in the rock groundmass. Other alteration mineral assemblages, possibly of hydrothermal origin, comprise muscovite, sericite, quartz, carbonate, associated with the sulphides pyrite and chalcopyrite. Although the occurrence of gold appears to be controlled by the presence of pyrite, it is also associated with silicification. Exploration methods have been proposed to target undiscovered gold deposits in the Ndori Greenstone Belt that are similar to the Masumbi deposit. These methods could probably be applied to vein-type gold deposits in other granite-greenstone terranes in the Lake Victoria Goldfields.

The Nebo-Babel Ni-Cu-platinum-group element (PGE) magmatic sulphide deposit, a world-class ore body, is hosted in low-MgO, tube-like (chonolithic) gabbronorite intrusion in the West Musgrave Block, Western Australia. The Nebo-Babel deposit is the first significant discovery of a nickel sulphide deposit associated with the ca. 1078 Ma Giles Complex, which is part of the Warakurna large igneous province (LIP), now making the Musgrave Block a prime target for nickel sulphide exploration. The Musgrave Block is a Mesoproterozoic, east-west trending, orogenic belt in central Australia consisting of amphibolite and granulite facies basement gneisses with predominantly igneous protoliths. The basement lithologies have been intruded by mafic-ultramafic and felsic rocks; multiply deformed and metamorphosed between 1600 Ma and 500 Ma. The Giles Complex, which is part of the Warakurna LIP, was emplaced at ca. 1078 Ma and consists of a suite of layered mafic-ultramafic intrusions, mafic and felsic dykes and temporally associated volcanic rocks and granites. The Giles Complex intrusions are interpreted to have crystallised at crustal depths between 15km and 30km and are generally undeformed and unmetamorphosed.

Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1995?
National Grid Reference Maitland Sheet I-553/12 (1:250 000) Whyalla I-53/8 (1:250 000). Three folded maps in pocket inside back cover. Includes bibliographical references (leaves 74-78).

Quatre parageneses successives decrivent la mise en place des mineralisations sulfurees de cambounes. Les 3 premieres sont dues a la remobilisation in situ d'une mineralisation stratiforme cambrienne lors de la deformation hercynienne majeure. La paragenese a antimoine, tardihercynienne est associee a des fluides hydrocarboniques et hypersalins. La paragenese a cu-pb est complexe et depend de la temperature de formation et de la proximite des mineralisations preexistantes

Les variations naturelles des isotopes stables du cuivre (masses 63 et 65) et du zinc (masses 64, 66, 67, 68 et 70) sont susceptibles de fournir de precieuses informations sur les cycles interne et externe de ces metaux et sur les processus d'echanges associes. Or, jusqu'a present, la geochimie isotopique des elements de transition a ete tres peu etudiee en raison de l'absence d'une technique analytique adaptee. Une procedure d'analyse des abondances isotopiques du cuivre et du zinc par spectrometre de masse a source plasma et multicollection (plasma 54) a ete mise au point. Les compositions isotopiques sont exprimees relativement a un standard (cuivre nist 976 ou zinc jmc). Pour les paires d'isotopes 6 5cu/ 6 3cu et 6 6zn/ 6 4zn, la precision analytique est de 0. 04& en unites delta. D'importantes variations isotopiques (9&) sont mesurees entre les mineraux de cuivre formes a basse temperature, sans que ces variations soient clairement reliees a la nature du mineral. Les compositions isotopiques du zinc montrent egalement des variations naturelles (0. 9&). D'autre part, l'analyse isotopique des deux metaux en trace dans des particules marines sedimentant a travers la colonne d'eau de l'ocean atlantique central (sites eumeli) met en evidence l'existence de variations isotopiques superieures a l'erreur analytique : 0. 12& pour 6 6zn, et 0. 25& pour 6 5cu. Les bilans elementaires et isotopiques indiquent un enrichissement en isotopes lourds au sein de la matiere organique lors de la remineralisation des particules. Plutot que des effets de source, des processus d'echange entre la phase particulaire et la phase dissoute semblent donc responsables des variations isotopiques observees au cours du temps. Ce travail montre donc que les rapports isotopiques du cuivre et du zinc mesures avec une grande precision peuvent etre utilises en tant que traceurs geochimiques et biogeochimiques.

Le gisement de beddiane appartient au district de touissit-bou beker, "chaine des horsts", maroc oriental. Il est encaisse dans la serie alleno-bajocienne, discordante sur le socle paleozoique, et se caracterise, par rapport aux gisements voisins, par sa richesse exceptionnelle en plomb, des concentrations exploitables de cuivre et peu de zinc. L'analyse sedimentologique de la formation carbonatee encaissante a permis de mettre en evidence des sequences transgressives et regressives, traduisant un environnement geologique instable: subsidences saccadees et emersions temporaires, suivies de phenomenes de dissolution-karstification pendant et apres le depot de la formation. L'examen petrographique a permis de distinguer plusieurs types de dolomies et de mettre en evidence deux phases principales de dolomitisation: un diagenetique precoce et une autre epigenetique, tardive. La lithogeochimie, effectuee a partir des carottes de sondages, a montre que toutes les assises carbonatees, sont fortement anormales en pb, zn et cu et plus particulierement les facies micritiques. Trois phases de mineralisations zn, pb et cu ont ete distinguees. La zonalite verticale et horizontale des mineralisations au sein du gisement et la geometrie des karsts mineralises suggerent que les solutions salines hydrothermales (100**(o)c) aient circule d'ouest en est dans cette couverture carbonatee. La presence dans le socle sous-jacent de filons a pb-cu pourrait temoigner d'une origine plus profonde des fluides mineralisateurs

Cette thèse est centrée sur la ceinture orogénique Attico-Cycladique formée durant l'orogénèse Alpine. Par une approche multi-méthodes et multi-échelles combinant géologie structurale, pétrographie, thermobarométrie des assemblages minéraux, géochimie élémentaire et isotopique, et données PVTX des inclusions fluides associées, ce travail vise à caractériser et comprendre les relations entre circulations fluides, interactions fluides/roches, déformation, et mobilisation-transport-dépôt des métaux. Les marbres et schistes de la péninsule du Lavrion et de l'île d'Eubée témoignent d'une évolution orogénique complexe marquée par une phase d'enfouissement à l'Eocène suivie par deux phases d'exhumation successives syn-et post-orogéniques. Les minéralisations de type Cu-Pb-Zn-Fe-Ag de la région du Lavrion sont synchrones de l’activation du détachement post-orogénique et de la mise en place de plutons de granodiorite. Leurs positions structurales témoignent d’un piégeage depuis un régime de déformation ductile jusqu'à fragile. Les minéralisations mises en place durant le régime de déformation ductile à ductile-fragile (skarn et remplacement de carbonate) sont associées à la décarbonatation des niveaux de marbres et à la circulation des fluides magmatiques. L'exhumation progressive de la racine orogénique se traduit par la transition des roches depuis une déformation ductile vers un régime fragile associé à l’ouverture du système aux fluides de surface et notamment aux fluides météoriques. Cette circulation est responsable d’une remobilisation des métaux des minéralisations primaires permettant alors une seconde phase de précipitation dans un régime cassant (veines épithermales)
This thesis is focused on the Attico-Cycladic orogenic wedge formed during the Alpine orogeny. From a multi-method and multi-scale approach using structural geology, petrography, mineral thermobarometry, element and isotope geochemistry, and PVTX data of associated fluid inclusions, this study deciphers the relationships between fluid circulation, fluid-rock interactions and mobilisation-transport-deposits of metals. Marbles and schists from the Evia Island and the Lavrion peninsula testify to a complex orogenic history marked by an Eocene burial phase followed by syn- and post-orogenic exhumation. Cu-Pb-Zn-Fe-Ag mineralisations from the Lavrion area are synchronous with the formation of the low-angle post-orogenic detachment and the emplacement of granodioritic magmas. The structural position of the deposits attests of an emplacement during ductile to brittle deformation conditions. Deposits associated with ductile to ductile-brittle deformation (skarn, carbonate replacement) are related to a marble decarbonation and magmatic fluid circulation. The progressive exhumation of the orogenic wedge allows the transition toward brittle conditions and opens the system to surficial meteoritic fluids. This meteoritic fluid circulation is responsible to remobilisation of metals from primary deposits allowing thus a second phase of deposition in a pure brittle deformation (epithermal veins)

L'etude petrogenetique des minerais de chessy-les-mines a permis de preciser la nature de la mineralisation et l'etude des deformations, de retracer l'evolution geologique complexe. Il est apparu que les metamorphismes ont amene une homogeneisation et une purification chimique des mineraux du minerai alors que leur recristallisation lors de la mise en place du granite a entraine un rajeunissement chimique. Cette approche petrogenetique et geochimique renforce la parente genetique entre chessy-les-mines et saint bel

L'evolution structuro-sedimentaire du secteur de taza est etudiee au lias et au paleozoique. Les mineralisations bpg montrent une zonalite horizontale et verticale. Leur age est discute sans solution par manque d'arguments tranchants

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The Moola Prospect situated within the Middleback Ranges on the northern Eyre Peninsula, South Australia, is comprised of potential IOCG-style, Cu mineralisation which appears to share some geological and mineralogical affinities with other IOCG deposits throughout the Gawler Craton. This recently identified mineralisation represents a new exploration region within the southern extent of the Olympic Cu-Au province which has proven to be highly lucrative with the recent discovery of the Hillside deposit in the neighbouring Yorke Peninsula. A broad investigation into host rock lithology, alteration and mineralisation paragenesis, as well as paleotemperature-pressure conditions of the deposit was carried out on drill core from OneSteel’s inaugural exploratory diamond drill hole. The mineralisation is hosted within the Paleoproterozoic Myola Volcanics, a package of rhyolites, rhyodacites and felsic gneisses which are intruded by amphibolite sills and granitic intrusives, assumed to be the neighbouring Wertigo granite. Prominently vein hosted, the mineralisation is localised around a north-northeast trending shear zone inferred to be an expression of the Kimban aged, Kalinjala shear zone which is located ~60 Km west of the Middleback Ranges. The alteration mineralogy present is divisible into two main assemblages, an early albite-epidote assemblage which has experienced extensive overprinting by the main mineralising phase associated with a quartz-carbonate-sericite± hematite-sulphide assemblage. Ore mineral paragenesis occurs as a transition of overlapping minerals that record coprecipiation. The first mineral to form was magnetite which was later extensively martitised during the transition to hematite precipitation which is preceded by a transition to pyrite, then finally chalcopyrite. A later phase of native copper mineralisation is recorded within the transecting shear zone which represents a supergene enrichment interpreted to have occurred as meteoric water gained access to depth via the structural weakness of the shear zone and remobilised any sulphides present, which were redeposited as native copper. The temperature of mineralisation was established by TitaniQ thermometry which provided a precise temperature range between 415-530 °C with the peak at ~475 °C, which represents the conditions at which the paragenically linked quartz and mineralisation formed. Chlorite thermometry was also performed to obtain a temperature of mineralisation, with a few samples corresponding with the conditions established by the TitaniQ thermometer; however a majority of the data overestimates the temperature range by an unacceptable amount. Pressure conditions were reconstructed using the much more reliable TitaniQ temperature range inconjuntion with fluid inclusion data to establish the pressure conditions of mineralisation which ranged between ~5-7 kbar, and indicated mineralisation occurred at a deep crustal setting. Fluid and mineralisation characteristics indicate a moderate salinity inferred from the fluid inclusions study, with NaCl ranging between 27.5-7.5 equiv wt%, along with a sulphur isotopic signature corresponding with magmatically derived fluids with the δ34S ranging between -10.5 and -1.2 ‰. Which corresponds with other IOCG style mineralisation present throughout the Craton, with the Moola Prospect also being spatially associated to the interpreted source of these fluids within the Galwer Craton, the Hiltaba Suite granitoids? Even though the Moola Prospect shares affinities with IOCG style mineralisation this study cannot definitively identify its model of genesis as it also comprises characteristics that contradict this model, indicating that further study is required to better understand the extent and nature of this mineralising system.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2010

Transported regolith has the capacity to mask underlying mineralisation by restricting the migration of most trace elements to the surface. Oxidation of sulphides generates highly mobile H+ which may migrate to surface, resulting in alteration of minerals and redistribution of elements within transported regolith cover. A detailed geochemical and geophysical study has been conducted at the Mandamah Cu-Au deposit in central-western New South Wales, where sub-economic mineralisation is covered by ~50 m of transported regolith and ~30 m of in situ regolith. A shallow-penetration electromagnetic survey was undertaken on nine transects and detailed mineralogical and selective extraction/ICP-MS geochemical analysis performed on regolith samples obtained from 107 soil cores and 16 pits spanning three extensive traverses across buried mineralisation. The selective extractions used were ammonium acetate, hydroxylamine.HCl and aqua regia. A distinct vertical zonation exists in the upper two metres of the transported regolith cover across the site and is related to soil mineralogy, soil pH, electrical conductivity and the amount of selectively extractable elements using the different geochemical extractions. The upper zone of near-neutral soil pH contains organic material but little carbonate; the intermediate high-pH zone has up to 2% Mg-calcite; the underlying low-pH zone displays Fe mottling. This zonation results from precipitation of salts due to evaporation, changes in redox potentials and accumulation of organic materials, in an otherwise relatively homogeneous quartz-clay alluvium. Ground conductivity measurements and selective extraction geochemistry display a strong response to parts of the underlying mineralisation. The principal signature is the depletion of Ca, S and Na, a reduction in the cation exchange capacity, the presence of non-carbonate alkalinity and a low electrical conductivity. A model to account for these patterns has been developed and involves a "prograde" stage of alteration of clay mineralogy and a redistribution of carbonates and various trace elements due to the development of an "acid chimney" above the oxidizing mineralisation during a period of elevated water tables and a "retrograde" stage involving a redistribution of some mobile elements back into the former acid chimney zone following the onset of more arid conditions. The results of this research demonstrate that the effects of sulphide mineralisation on the upper transported regolith at Mandamah can be detected using a combination of selective extraction geochemistry and shallow depth conductivity measurements. This technique has potential application in similar arid to semi-arid terrains.

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The Kanmantoo Cu-Au deposit has been in episodic operation since 1846, one decade after the capital city of Adelaide was established some 40 kilometres to the NW. Regionally and within the host stratigraphy there exists archetypal evidence of the Cambrian Delamerian Orogeny through a complex structural, metamorphic and intrusive history. Consequently, numerous theories exist within the literature regarding a syngenetic or epigenetic style of mineralisation and the debated contribution, if any, of magmatic hydrothermal fluids. This study has documented numerous felsic intrusive vein sets within the Kanmantoo Cu-Au deposit which have been utilised to constrain the role of igneous activity on mineralisation within a wider Delamerian context. Monazite U–Pb ages of felsic veins show that intrusion first occurred at syn-peak metamorphic, syn-orogenic conditions (495.11 ± 2.79 Ma), continuing periodically until post-peak metamorphic, extensional conditions (483.43 ± 2.52 Ma). Intrusions are coeval with mineralisation and are temporally and geochemically analogous to magmatic activity in the adjacent Monarto and Murray Bridge provinces. Analysis of trace elements in monazites identifies the Kanmantoo Cu-Au deposit as a syn- to post-peak metamorphic hydrothermal anomaly which, combined with the presence of felsic veins, indicates that mineralisation resulted partly from fluids generated by a pluton at depth. These findings broadly confirm the prospectivity of Delamerian-affected terranes throughout large parts of South Eastern Australia where pervasive intrusive geology exists.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2018

Continental magmatic arcs host economically important porphyry ore deposit types for copper, gold, and molybdenum, and, if preserved, epithermal high- to intermediate-sulfidation gold and silver deposits. These deposits are genetically and/or spatially associated with magmatism, so understanding the link between magmatism and mineralisation is seen as a crucial endeavor to assist knowledge of mineralisation processes and strategies for regional-scale mineral exploration. This thesis examines aspects of the mineralisation potential of continental arc magmatic rocks that are exposed as part of the Permo-Carboniferous Kennedy Igneous Association (KIA) from northeastern Queensland. This belt of upper crustal intermediate to felsic granitoids and associated volcanic rocks is recognised to host many economic ore deposits related to igneous activity. Using well-established analytical techniques to analyze whole-rock and mineral major- and trace element compositions combined with Sm-Nd isotopes, I investigate two different localities related by their occurrence in time and space, with the aim to better understand magma fertility, or more specifically the petrogenetic processes contributing to Permo-Carboniferous Cu-Au mineralisation in northeast Queensland. This work strives to improve the applicability of magma fertility concepts to confidently identify fertile igneous terranes potentially covering high grade Cu-Au deposits at depth. The first location investigated lies to the south of Townsville at the northern edges of the Bowen Basin, where the early Permian Lizzie Creek Volcanic Group (LCV) hosts the Mount Carlton high-sulfidation epithermal Au-Cu deposit. Established whole-rock geochemical parameters, e.g. Sr/Y, V/Sc, used to distinguish fertile porphyry Cu-Au hosting intrusive rocks from barren intrusions, were tested on the "fertile" LCV succession, hosting the Mt. Carlton deposit and compared to contemporary "barren" volcanic rocks of the same group. The results reveal that the key control on generating the fertile LCV sequence was a high magmatic water content, reflected by early fractionation of amphibole at the source level, whereas the barren sequence was comparably dry, and formed by typical fractionation of plagioclase and clinopyroxene. This outcome has major implications for the applicability of whole rock geochemistry as a magma fertility indicator. The here presented results suggest that for volcanic rocks, which tend to be affected by hydrothermal alteration; a) Sr/Y is not a reliable fertility proxy and; b) Rare earth element ratios (e.g. La/Yb, Dy/Yb), which are relatively resistant to alteration, can be used to reveal differences in magmatic evolution. This supports previous research on magma fertility, and provides strong evidence that fertile magmatic suites can be identified from volcanics sequences that evolved from basalt to rhyolite with a progressive increase in La/Yb, decreasing Dy/Yb, and consistent or slightly increasing V/Sc ratios, despite having experienced some degree of alteration. The second location investigated in this thesis is the Tuckers Igneous Complex (TIC); a calc-alkaline, I-type igneous complex which intruded the Ravenswood Batholith between ~300-290 Ma and formed within the same convergent margin as the LCV. The TIC is part of the KIA and its relevance for this project lies within its close association with the major early Permian, breccia-hosted Mt. Leyshon Au deposit. The TIC contains a sequence of intrusive rocks from gabbro to felsic granodiorite, and hence offers the opportunity to investigate geochemical evolution, particularly volatile element evolution, of arc magmas at upper crustal levels. Here, I build on previous geochemical and petrographic data for the complex using newly acquired whole-rock geochemistry and in-situ mineral analyses of the major rock forming minerals plagioclase-clinopyroxene-orthopyroxene, and the halogen-bearing minerals apatite and biotite (and amphibole) to monitor and track volatile evolution (Cl and F). As volatile element behavior is recognised to have a fundamental control on magma fertility, this study, offers new insights into the fertility of this Permo-Carboniferous arc, which can be applied to other arc worldwide. My new results show that the TIC formed through closed-system crystal fractionation from gabbro to mafic granodiorite varieties with only minor mixing and/or assimilation, and likely became an open system during cooling and crystallisation of the more felsic granodiorites. Based on apatite halogen contents, volatile saturation is suggested to have occurred at around ~63-65 wt.% bulk-rock SiO₂, up to which point estimated Cl melt contents steadily rise, and then suddenly drop from ~0.8 to 0.4 wt.%. This abrupt change likely relates to the exsolution of a Cl-rich volatile phase, and also marks important changes within the mineral assemblage from a dry Plag ± Px ± Fe-Ti oxide assemblage, towards a more hydrous and slightly more oxidised Plag ± Hbl ± Bt ± Mag assemblage. Fluorine enriches in the melt with fractionation, even once saturation in a volatile phase is reached, consistent with what is expected from experimental partitioning studies in the system apatite – melt – fluid. Local or temporal changes in the magma's fO₂ is indicated by a measurable increase in apatite S contents in evolved felsic granodiorite, as apatite preferentially incorporates S as its oxidised species S⁶⁺, which also coincides with the general observed changes in the rock forming mineral assemblages as described above. Indicated volatile exsolution, causing loss of significant proportions of Cl together with oxidising conditions at which the bulk of dissolved S may have been present and possibly degassed as S⁴⁺O₂ (and causing the presence of low amounts of available S²⁻ to precipitate base metals) from the TIC magma may have caused mineralization within overlying, but now eroded rocks. A second possibility may be that the TIC was never able to produce mineralising fluids due to early segregation of sulfides, scavenging ore forming metals (e.g. Cu, Au, and Ag) prior to the crystallisation of TIC gabbro, and thereby stripping the TIC of its ore-forming potential early on. However, an exsolved Cl-rich fluid is very capable of transporting ore metals, therefore the role and true nature of such fluid(s) originating from the TIC can be subject of further investigations. The here presented results help to understand Cu-Au fertility on a regional, magmatic arc terrane (both volcanic and intrusive) from initial lower crustal petrological processes to the surface, but also on a local scale; within confined individual igneous bodies, their respective mineral assemblages, and their potential role towards regionally present Cu-Au mineralisation. In particular the findings on volcanic rocks offer great potential as easily accessible first-order fertility assessment tool for magmatic-hydrothermal Cu-Au exploration worldwide.

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Iron oxide copper gold (IOCG) systems display well-developed spatial zonation with respect to alteration assemblages, mineralogy and the distribution of rare earth elements (REE). The Middleback Ranges, South Australia, located in the Olympic Province, Gawler Craton, hosts anomalous Fe-oxide-bearing Cu-Au mineralisation, and are considered potentially prosperous for larger IOCG-style deposits. This study investigates whether the distribution of REE and other trace elements within selected minerals represents a potential exploration tool in the area. Iron-oxides (hematite and magnetite), potassium feldspar, albite and accessory minerals have been analysed by laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) from two prospects (Moola and Princess) and in samples of the Myola Volcanics. The resultant multi-element datasets are compared to other IOCG systems. The results support the presence of sizeable and/or multiple IOCG alteration envelopes within the Middleback Ranges. Significant evolving hydrothermal events resulted in hydrolithic alteration and remobilisation of REE within the Moola Prospect and Myola Volcanics. Replacement of early magnetite by hematite (martitisation) in the Myola Volcanics is accompanied by an influx of REE visible on LA-ICP-MS element maps showing partial martitisation at the grain-scale. It is thus inferred the initial generation of magnetite must have pre-dated introduction of oxidised, REE-enriched hydrothermal fluids into the system. Sulphide assemblages observed within the Moola Prospect are complex and record sequential recrystallisation under evolving fS2 and fO2 conditions. Trace minerals, cycles of brecciation and replacement, and distributions of REE within minerals are similar to that observed in other IOCG domains. The Princess Prospect displays REE distributions in minerals which are dissimilar to the Moola Prospect, the Myola Volcanics and also those reported from other IOCG domains. This is interpreted as indicating that the Moola Prospect and Myola Volcanics in the south of the Middleback Ranges are more prospective IOCG targets.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2013

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The world-class Boddington Cu-Au-Mo deposit has a complex genetic history. The relative importance of different ore-forming processes during the period 3.0 – 2.6 Ga is debated, particularly with respect to the role played by the 2611±3 Ma Wourahming granite. LA-ICP- MS analysis of trace element concentration in molybdenite represents a valuable new metallogenetic tool to track mineralising events in deposits with protracted geologic histories. The Re content and trace-element signatures in molybdenite from diorite and granite show three distinct populations, attributed to porphyry-style (hundreds of ppm) orogenic- and granite-related systems (<1 to a few ppm, respectively). Rhenium concentrations in molybdenite are highly variable on the deposit-scale. Economic concentrations of Re occur only at shallower levels in both Central Diorite and ABreccia. The Au content correlates with high-concentrations of chalcophile elements (CE). This is seen in the association of Au- minerals and Bi-(Pb)-tellurides present as inclusions in the molybdenite from diorite and is inferred from an LA-ICP-MS element map for molybdenite in granite. The FIB-SEM and TEM study show that visible telluride inclusions extend down to the nanoscale as coherent intergrowths with host molybdenite. Nanoporosity is accompanied by a whole range of structural defects and twinning. The telluride species identified include unnamed Bi4Pb7Te4S9. Analysis of stacking sequences show co-precipitation of Bi-tellurides and molybdenite under equilibrium conditions. In corroboration with EPMA data, this is the first confirmation that minerals from the aleksite series are characteristic components of the ore at Boddington. Molybdenite with high-concentration of chalcophile elements is present as the 2H polytype only, contrary to previous hypothesis that incorporation of trace elements is assisted by 3R structural modification. Instead, a new mechanism is presented in which coherent lattice-scale intergrowths between molybdenite and tellurides are reasons for the measured high CE concentrations. Knowing that Bi-(Pb)-tellurides are Au-carriers, this may also explain the observed, unusual Au-enrichment in molybdenite from Boddington. Nucleation of Au fine particles is inferred from element map correlations but further work is necessary to prove if Au nanoparticles are also present. Petrographic, mineralogical and geochemical evidence support a three-stage model for Boddington. An early porphyry event can account for the bulk of the Cu mineralisation, as well as some of the Au and Mo. A subsequent orogenic-Au event led to shearing and remobilisation of ore components. New constraints on metamorphic conditions are offered by chlorite and stannite-sphalerite geothermometry (200-420 °C) and the occurrence of two co- existing pyrrhotite species. The granite introduced some Au, Mo and other „granitic‟ elements, notably Bi leading to substantial upgrading of Au grades by Bi-melt scavenging. The study concludes however that hydrothermal activity associated with granite was not the most important concentrator of ore minerals.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2011

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The Palaeoproterozoic Poodla Granite within the Olary Domain, Curnamona Province, South Australia, has been suggested as a direct contributor to Cu-Au mineralisation within the region on the basis of age correlations. Alteration present within the Poodla Granite consists of four styles that have been interpreted as two events. The first event includes pervasive potassic alteration followed by pervasive Na-Ca alteration. Sm/Nd isotope analysis indicates fluids for this event were sourced from the Willyama Supergroup sediments. The second event consists of fracture-controlled sodic and Ca-Na-Si alteration with associated actinolite/clinopyroxene brecciation. Utilisation of magmatic major element trends obtained from a natural analogue (Mt Angelay Complex, Cloncurry District) has allowed greater accuracy in chemical characterisation of alteration. Fluid inclusion analysis has identified two distinct fluids involved in the later fracture-controlled sodic and Ca-Na-Si alteration event. Namely, a low salinity (18-26wt% NaCl equivalent) and a high salinity (35-45wt% NaCl equivalent) fluid. A later fluid mobilisation event related to the Palaeozoic Delamerian Orogeny is indicated by re-equilibration of the Rb/Sr isotopic system. New age constraints from other granites in the I-type suite, to which Poodla Granite belongs, suggest the Poodla Granite did not have direct hydrothermal input into regional Cu-Au mineralisation. Analysis of alteration chemistry suggests that Cu and Au mobilisation occurred during the first alteration event. These results offer evidence for previously untested Cu-Au mineralising models within the region and may encourage exploration for Cu-Au resources.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2003

The Eastern Fold Belt (EFB) in north-west Queensland, Australia, is an extensively metasomatised terrain that contains a variety of Fe oxide (Cu-Au) and related deposits (IOCG). Most of these deposits formed after the peak of ca. 1600-1575 Ma regional metamorphism and exhibit a broad range of mineralogical and chemical associations. The origin of fluids associated with mineralisation is particularly controversial, whereby magmatic, non-magmatic and magmatic-evaporitic fluid-derived models have all been proposed. Several deposits in the district also exhibit different relations to ironstone (Fe oxide-rich rock) occurrences. These relations vary from early to pre-mineralisation Fe oxides (Starra and Osborne), syn-mineralisation Fe oxides (Ernest Henry) and examples where significant amounts of Fe oxide are distal to the site of mineralisation (Eloise). Fe oxide-rich rocks can form from a number of different processes (orthomagmatic, replacement, infill, sedimentary), and can be distinguished by textural observations and geochemical analysis. Sulphide mineralisation and Fe oxide-rich rocks within the Mount Fort Constantine (MFC) exploration lease (the main study area) are of particular interest due to their proximity to the Ernest Henry (Cu-Au) deposit. At the FC4NW and FC12 prospects in the MFC lease, sulphide mineralisation post-dates the formation of Fe oxide-rich rocks and is associated with amphibole-rich Na-Ca alteration. Fe oxide-rich rocks in the FC12 prospect were formed by orthomagmatic processes directly related to the formation of their tholeiitic gabbroic host. In contrast, Fe oxide-rich rocks in outcrop and at the FC4NW prospect were formed by hydrothermal processes. Fe oxide-rich rocks at the FC4NW prospect exhibit a close spatial and temporal association with an earlier clinopyroxene-rich Na-Ca alteration phase that predates sulphide mineralisation. The poor correlation between Fe oxide-rich occurrences and sulphide mineralisation at MFC differs from Ernest Henry, where Fe oxide and Cu-Au mineralisation are synchronous and post-date Na-Ca alteration. Na-Ca alteration at FC12 is associated with the enrichment of Fe, Mg, REE, Cu and S. In contrast, Fe is typically depleted and Mg, REE, Cu and S are variable in regional Na-Ca alteration throughout the Cloncurry District. Na was also found to be variable at FC12. These geochemical patterns suggest that the fluids at FC12 were cooler and more evolved than for regional Na-Ca alteration, and had previously undergone significant fluid-rock interaction prior to mineral precipitation. This is reflected in the low temperature mineral assemblage (chlorite, calcite, magnetite, hematite, pyrite, chalcopyrite) associated with these veins. Na-Ca alteration at FC4NW formed by a hypersaline (25 to 50 wt% NaClequiv) and CO2-bearing fluid at temperatures of around 260 to 442°C. These fluids cooled and became less saline with time, reflecting the transition from clinopyroxene-rich to amphibole-rich Na-Ca alteration. The chemistry of these fluids is similar to regional Na-Ca assemblages, containing elevated Mn, Zn, Cu, Fe, K, Cl, Ca, Ba and Pb. In contrast, they are distinctly different to fluids associated with Cu-Au mineralisation at Ernest Henry, Starra, and Lightning Creek in the EFB. In particular, Mn, Zn, Ba and Cu concentrations are significantly lower in Na-Ca assemblages from FC4NW. The lack of significant Cu-Au mineralisation at FC4NW may be attributed to the low Cu content in the fluid. The mineral chemistry of magnetite, hematite, pyrite and chalcopyrite can be used to discriminate between Cu-Au mineralised systems and systems which are weakly mineralised to barren. Magnetite associated with Cu-Au mineralisation contains a greater variety of elements including Mo, W, Th and U, which are typically low to below detection in other systems. In addition, Cu-Au mineralised systems are associated with higher Sc and Mn (magnetite), As and Co (pyrite), Bi, Sn, In and Ag (chalcopyrite) and As, Sb, Ga, and W (hematite). In contrast, Ti, V, Ga and Cr (magnetite) and Se and Ni (pyrite) are lower in Cu-Au mineralised systems. Fluid chemistry is interpreted to be the dominant control on the trace element content of magnetite, hematite, pyrite and chalcopyrite, however, other physicochemical factors including fO2 and temperature may also affect the relative concentration of elements including V, Cu and Se. These chemical signatures have the potential to be used as vectors towards geochemical haloes peripheral to Fe oxide (Cu-Au) mineralisation. The presence of granitic and pegmatitic dykes at FC12 and FC4NW suggests the presence of a nearby igneous intrusion. In contrast, no igneous intrusive phases are present at Ernest Henry. The felsic igneous rocks at FC4NW exhibit a close spatial and temporal relationship to clinopyroxene-rich Na-Ca alteration suggesting a genetic link. The presence of sulphide associated with the latter amphibole-rich Na-Ca phase at FC4NW, together with the low temperature mineral assemblage associated with Na-Ca alteration at FC12, suggests that mineralisation may have occurred due to a drop in temperature over time, irrespective of the specific mechanism responsible for the precipitation of sulphide. The paragenesis and fluid inclusion chemistry at MFC suggest that sulphide mineralisation is an earlier / unrelated event compared to the phase of Cu-Au mineralisation at Ernest Henry. Instead, sulphide mineralisation at MFC more closely resembles the early, weakly mineralised Na-Ca alteration phase and related hanging wall Fe oxide-rich rocks at Ernest Henry. The main ore genesis stage at Ernest Henry is noted by a more complex fluid chemistry, in addition to the presence of Au (absent at MFC) and K-Fe alteration, which suggest that at least one fluid associated with Cu-Au mineralisation at Ernest Henry was absent at MFC. However, the whole rock geochemistry of low temperature Na-Ca alteration at FC12 as well as the mineral chemistry of Fe oxides and Fe sulphides suggest that sulphide mineralisation at MFC and Ernest Henry may be more implicitly linked. In particular, magnetite associated with sulphide-bearing Na-Ca alteration at FC4NW and FC12 contain high Ni and anomalous W, Mo, Th and U, the latter of which are minor to absent in barren regional Na-Ca assemblages but highly enriched at Ernest Henry. One possibility is that Ernest Henry is part of an overlapping hydrothermal system, which supports the interpretation by Mark et al (1999) that more than one fluid was responsible for Cu-Au mineralisation. Fluids responsible for sulphide mineralisation at MFC may have either been diluted by another fluid, possibly of meteoric origin, or did not mix with a more chemically complex, S-bearing fluid. Thus, while a clear distinction can be made between sulphide mineralisation at MFC and Cu-Au mineralisation at Ernest Henry both chemically and paragenetically, MFC may represent a vector towards mineralisation at Ernest Henry, because a small amount of potentially ore-bearing Ernest Henry-style fluid appears to have contributed to the MFC magnetite geochemistry.

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Copper mineralisation within the Mount Isa Mines deposit is associated with variable talc alteration. An understanding of the mineralogy and distribution of talc alteration associated with the northern 3500 orebody is important for future mining processes and could potentially be used for exploration targets around the Mount Isa area. Mineralogical and geochemical investigations have shown one major type of talc mineralogy throughout the entire 3500 orebody. Variations in colour and texture are visible macroscopically and microscopically but there are no distinctive differences in mineralogy. The talc has minor iron (~4 wt% FeO), probably due to the moderate iron within the Mount Isa system. The same type of moderately Fe-rich talc is found within the 1100 oreobody (Waring, 1990), suggesting a similar style of talc alteration extends beyond the 3500 orebody. The distribution of talc is reliant on the fluid pathway. The altering fluids have used selected faults within the 3500 orebody as pathways. The NSFW fault which roughly defines the eastern limit of mineralisation in the 3500 orebody is typically a strong wide shear zone with talc fill and is recognised as being a possible pathway for the fluids. Talc is dominant on the footwall of the 3500 orebody from south of 6700mN and dominant on the hangingwall, north of 6700mN. Within the siliceous core where mineralisation is at its greatest concentrations, talc is only located within faults. Outside the siliceous core where copper mineralisation is lower, talc alteration is present within the rocks and varies in quantity. The talc alteration has occurred after the formation of dolomite and pyrite. However, the timing of the talc alteration in relation to the copper mineralisation remains unknown. Four methods of determining the most accurate and cost effective method for talc abundance estimates within the 3500 orebody are evaluated. The most effective method is through the calculation of stoichiometric equations from XRF assay data. These calculations can be used to create an accurate talc 3D numerical model that enables the distribution and numerical quantity of the talc to be viewed throughout the copper mine.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2004

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy, October 2018
Mashitu South is a Cu-Co deposit situated in the Katanga Province of the Democratic Republic of the Congo (DRC), about 25km to the east of the city of Kolwezi. It lies within the northwestern portion of the Central African Copperbelt (CAC), an arcuate region with a world class abundance of copper deposits that straddles the external-fold-and-thrust-belt and the Domes region of the Lufilian arc, an orogenic belt that formed during the ∼600-500Ma Pan African orogeny. Cu-Co mineralisation at Mashitu South is hosted in the rocks of the Mines Series and Roches Argillo-Talceuses (RAT) subgroups of the Roan Group, deposited during the early stages of the opening of the Katangan basin, which is constrained to a maximum age of ∼880Ma. This study characterises the mineralisation stages and geochemistry of Mashitu South through a combination of core logging, geostatistical and petrographic techniques. The mineralogical and geochemical changes which occurred to the deposit throughout its paragenetic history are also explored. This is done with the purpose of linking the mineralisation at the deposit to regional metallogenic and geodynamic events, as well as developing vectors to Cu-Co mineralisation. Mineralisation at Mashitu South occurred in four stages. The first stage is characterised by the development of stratiform-disseminated, zoned Cu-Co sulphides restricted to the rocks of the Mines Series, in a manner comparable to the sedimentary hosted stratiform copper (SSC) deposit model. A protracted, syn-diagenetic timing is inferred for this stage, which caused the formation of hypogene, stratiform orebodies, primarily in the Kamoto Formation. Metals emplaced during the first stage were remobilised during the second mineralisation stage, which resulted in the development of vein-hosted hypogene Cu Co sulphides, but does not appear to have concentrated metals into significant orebodies at Mashitu South. The second period of mineralisation is inferred to be early/syn-orogenic in age. Hypogene mineralisation at Mashitu South is found to have an element association of Cu + Co + Bi + Ni + V + S ± Mo ± As ± Fe ± Zn. The deposit was subsequently affected by two discrete stages of supergene alteration and mineralisation. Supergene alteration has resulted in the in-situ oxidation of hypogene Cu-Co sulphides, and also the leaching and remobilisation of metals from hypogene mineralisation. The leaching and remobilisation process formed supergene, malachite-dominated orebodies which have an element association of Cu + Be + P ± Zn, the location of which is primarily controlled by metal availability and permeability of the host rocks. The RAT Subgroup is frequently host to such orebodies, underneath leached and eroded away Mines Series strata. These orebodies are usually found at a depth of ∼30 50m. An occurrence of bacillus-shaped features composed of Cu-Co sulphides was discovered in the lower Shales Dolomitique du Base (SDB) unit of the Mines Subgroup, and investigated with respect to the potential biogenicity and antiquity of the features as candidate microfossils. Further study found these features to be pseudofossils formed primarily by the replacement of diagenetic rutile crystals by sulphides, during the primary, stratiform mineralisation stage. The various elements of the hypogene geochemical association are shown to have different mobilities in the supergene leaching environment, with Cu being relatively mobile and Co + Bi + Ni + V ± Mo being relatively refractory. This variation in mobility between elements, which are associated with Cu in the hypogene environment, suggests a zonation of these elements around Cu in the supergene environment, controlled by the hydrological gradient. At Mashitu South, this has resulted in the relative enrichment of Bi, Mo, V and Co in the upper 10m of the rock profile. Nickel is not as depleted in this interval as Cu, which is strongly depleted in the near-surface environment. It is therefore hypothesised that Bi, Mo, V, Co and Ni would make better surface vectors towards buried Cu-Co mineralisation than Cu, in regions where the supergene leaching process is particularly effective. ‘Cobalt caps’ above Cu-Co deposits in Katanga are well known, but this study suggests that Bi, Mo and V may make even better surface vectors to mineralisation than Co.
XL2019

Analizowany w niniejszej pracy obszar badań „Sulmierzyce-Odolanów” stanowi przykład występowania głębokiej cechsztyńskiej mineralizacji metalicznej na monoklinie przedsudeckiej. W przeciwieństwie do eksploatowanych obecnie złóż płytkich, tego typu obszary nie były wcześniej brane pod uwagę pod kątem ewentualnego wydobycia. Jednakże w ostatnich latach, ze względu na rozwój nowoczesnych technologii górniczych, sytuacja ta uległa zmianie i zyskały one status perspektywicznych dla przyszłego dokumentowania złóż. Graniczne parametry wyznaczające złoże, zalecane do stosowania przy przygotowywaniu dokumentacji geologicznej i nieobowiązkowe, ustanowione zostały rozporządzeniem Ministra Środowiska. W przypadku stratoidalnych złóż cechsztyńskich biorą one pod uwagę ekwiwalentną zawartość i zasobność jedynie dwóch metali, tj. miedzi, jako głównego składnika użytecznego, oraz srebra. Prowadzi to do niedoszacowania zasobów rud, w których występują także inne metale, m.in. cynk i ołów, co jest szczególnie niekorzystne w przypadku złóż głębokich, gdzie z ekonomicznego punktu widzenia wskazane jest koncentrowanie się na ich najbogatszych partiach oraz dokumentowanie, a w przyszłości wydobywanie wszystkich użytecznych metali. Rozporządzenie Ministra Środowiska nie uwzględnia także wahań rynkowych cen metali w czasie, które mają istotny wpływ na zawartość i zasobność ekwiwalentną tych pierwiastków w złożu. W niniejszej pracy zaprezentowano autorskie wzory mające na celu obliczanie zawartości i zasobności polimetalicznego ekwiwalentu uwzględniającego udział w rudzie czterech pierwiastków: miedzi, srebra, cynku i ołowiu. Umożliwiają one także oznaczanie tych wartości dla dowolnie wybranych przedziałów czasowych oraz śledzenie ich zmian w czasie. Poza parametrami jakościowymi możliwe jest również obliczenie wartości zasobów kopaliny w złożu wyrażonej w dolarach amerykańskich na metr kwadratowy jego powierzchni dla każdego z wybranych przedziałów czasowych. Do obliczeń wykorzystano wyniki analiz chemicznych archiwalnych rdzeni wiertniczych pochodzących z badanego obszaru. Łącznie przeanalizowano 135 otworów archiwalnych położonych w jego granicach. Na podstawie uzyskanych wyników oszacowano zmienne w czasie zasoby ekwiwalentu polimetalicznego (Cu-Ag-Zn-Pb) oraz ich wartość rynkową wyrażoną w dolarach amerykańskich dla każdego roku w przedziale czasowym 2012-2016. Rezultaty badań opatrzono stosownymi komentarzami i wnioskami oraz przedstawiono graficznie na mapach izolinii zasobności i wartości pieniężnej kopaliny sporządzonych dla poszczególnych lat.
The “Sulmierzyce-Odolanów” study area analysed in the present thesis constitutes an example of the presence of deep Zechstein metallic mineralisation in the Fore-Sudetic Monocline. Unlike the shallow deposits which are being mined nowadays, these types of areas were not previously considered in terms of their possible extraction. However, in the recent years, due to the development of modern mining technologies, this situation has changed and these areas have become prospective for the future documenting of mineral deposits. The threshold parameters delimiting an ore deposit, recommended for use when preparing geological documentation and not compulsory, have been established by the regulation of the Minister of Environment. In the case of stratabound Zechstein deposits they take into account the equivalent percentage and productivity of only two metals, i.e. copper, as the main useful component, and silver. This leads to the underestimation of the resources of ore which also contains other metals, including zinc and lead, which is particularly disadvantageous in the case of deep deposits, where from an economic standpoint it is advisable to focus on their richest parts and to document, and in the future to extract all useful metals. Also, the regulation of the Minister of Environment does not take into account the fluctuations of the market prices of metals over time, whose impact on the equivalent content and productivity of these elements in the deposit is considerable. This thesis presents the author's own formulas intended to calculate polymetallic equivalent content and productivity taking into account the share of four elements in the ore: copper, silver, zinc and lead. They also enable determining these values for arbitrarily selected time intervals and tracing their changes over time. Apart from quality parameters it is also possible to calculate the value of mineral resources in the deposit expressed in American dollars per one square metre of its area for each selected time interval. The calculations used the results of chemical analyses of historical drill cores originating from the studied area. A total of 135 historical holes located within its boundaries were analysed. Based on the obtained figures, the time-varying resources of the polymetallic equivalent (Cu-Ag-Zn-Pb) were estimated along with their market value expressed in American dollars for each year in the time interval of 2012-2016. The research results were accompanied by appropriate commentaries and conclusions and presented graphically on the contour maps of the productivity and financial value of ore prepared for the individual years.

Major geophysical lineaments are commonly associated with active to ancient faults at a variety of scales. They may correlate with the edges of rifts, depositional basins, orogenic belts or plate boundaries, and they commonly represent corridors along which deformation, mineralisation, magmatism and intra-crustal heat flow is concentrated. In many instances, they encompass a number of these features. The Cloncurry Lineament, a major feature in wavelet processed magnetic and gravity potential field (worm) data over the Mount Isa Inlier Eastern Succession, displays several such characteristics. It is over 200 km long and inferred to extend to at least 30 km depth. It delineates a contact between two major Paleoproterozoic sedimentary sequences, implying that it originated as a normal fault during rifting and basin formation. Magnetic forward modelling results suggest it corresponds to the eastern margin of a 5-10 km wide deformation zone within the calc-silicate Doherty Formation; the Cloncurry Fault Zone. The Cloncurry Fault Zone encompasses a continuum of deformation from ~1.6 to1.5 Ga. While D₁-D₂ deformation is regionally dominant, D₃ is more significant in the fault zone itself as evidenced by much lower temperatures during mylonitisation (500- 350°C) and the superimposition of mylonitic fabrics on Maramungee aged (~1550 Ma) granites. Mapping and structural fabric analysis of the Cloncurry Fault Zone show that D₃ involved WSW shortening, sub-perpendicular to a pre-existing basin-bounding fault. D₃ created an anastomosing shear zone system displaying variable slip vectors with synchronous variably NNW or SSE plunging folds. Penetrative fabrics are attributed to strain partitioning in the D₃ event, rather than a more complex history of overprinting. During D₄-D₅ a sinistral Riedel strike-slip fault system formed, coincident with massive Na-Ca brecciation. Intrusive magmatism and IOCG, Cu, and Au mineralisation also occurred during the D₃-D₅ history of the Cloncurry Fault Zone, highlighting its importance as a magmatic and hydrothermal pathway. Sodic-calcic (Na-Ca) metasomatism, associated with Cu-Au mineralisation in the Mount Isa Eastern Succession, is widely recognised but heterogeneously distributed, and difficult to map regionally. Hence, a method to map Na-Ca alteration remotely was developed. ASTER Band ratios were ineffective for mapping amphiboles and carbonates as a proxy for sodic-calcic alteration due to numerous mineral species having similar absorption features in ASTER band 8. Therefore, the low Kradiometric and highly magnetic properties of Na-Ca alteration were integrated with ASTER band 8 to form a Sodic-Calcic Alteration Index. The Index highlights albiteactinolite- magnetite assemblages that are coincident copper with Cu-Au mineralisation in the Eastern Succession, and the Index is useful for regional exploration in the Mount Isa Inlier. Weights-of-evidence analysis identifies the Cloncurry Lineament as an important crustal-scale control on Au, Au-Cu, Cu-Au, and Cu mineralisation, and autocorrelation is used to identify local structural controls within the broad regional control. This integrated approach, using worms and weights-of-evidence and autocorrelation, may prove a useful exploration tool for mineralised terrains under Phanerozoic cover. Mineralisation along the Cloncurry Lineament appears to be facilitated by two main factors. Firstly, it is associated with long, deep-crustal structure lying above dynamic lower crust/mantle, which has concentrated magmatism and metasomatism. Secondly, the associated structures have been repeatedly reactivated; increasing the chances that dilation may coincide in space and time with upflow of mineralising fluids to form a mineral deposit. These two factors appear to be consistent in several of the world's major mineralised lineaments.

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The Moonta-Wallaroo area has been of economic, historical and scientific importance in South Australia's history for over 130 years. The nature of mineralisation in the area has long been a point of conjecture. This study looks at the nature of ore deposition and specifically its relationship to granitoids and pegmatites in the Moonta Subdomain. Using various analytical techniques the study has shown that granitoids in the region have distinctly different petrological, textural, structural, geochemical and isotopic characteristics. Two main granitoids were·recognised as the Tickera Granite and the Arthurton Granite. Geochemical studies suggest that magmatism in the Moonta Subdomain was a continuous process in the Mesoproterozoic. The older Tickera Granite, displays syn-collisional, more I-type characteristics and syn-collisional S-type characteristics (represented by a monzonite and a tonalite respectively). The younger Arthurton Granite shows A-type, anorogenic characteristics. A temporal shift from syn-collisional to anorogenic granites suggests a tectonic control on magma generation and emplacement during this period. Trace element characteristics of the Arthurton Granite are homogeneous over a wide spatial range, is suggesting that it may be part of an extensive batholith. Geochemistry of pegmatites implies that they were late stage fractionation products, related to these granite intrusions. A study of the Tickera Granite (Point Riley-Nth Beach) revealed a dominant structural fabric which suggested the granite was intruded into a tectonic regime in which shearing was prominent. Sediments intruded by the granite suggested deposition in a shallow intracratonic rift setting, followed by polyphase deformation during orogenic activity and subsequent shearing possibly related to the enigmatic Wartakan Event. Isotopic studies highlighted differences in the petrogenetic source regions of the Tickera Granite and the Arthurton Granite. The Tickera Granite (represented by monzonite) displayed more mantle like characteristics while the Arthurton Granite (represented by granite from Arthurton and adamellite from Moonta) displayed more crustal features, highlighting its A-type nature. Studies also showed that a pegmatite from the Wheal Hughes was most like the later of these two granites. Tourmaline studies of Wheal Hughes samples implicated derivation from a metapelite and calcsilicate precursor, a common feature of most tourmaline studied in the area. This may indicate remobilisation of boron rich fluids and metals from these sediments The close association of tourmaline with the ore in the Moonta Mines region implied a common source region. A tectonic setting and model for ore deposition is proposed on the basis of the study findings. The model proposed the remobilisation of metals which were initially deposited in a ensialic rift type environment (common to other Palaeoproterozoic metalliferous terrains) by the intrusion of the Tickera Granite, during regional shearing. And further concentration of metals by subsequent intrusions of the Arthurton Granite batholith.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1994

The Eastern Succession of the Proterozoic Mt Isa Block, including the Cloncurry District and the Mary Kathleen Fold Belt (MKFB), contains numerous examples of Fe-oxide-Cu-Au mineralisation. Most deposits, including Ernest Henry, Eloise, Starra and Mt Elliott formed after the peak of ca. 1600-1575 Ma upper greenschist to amphibolite facies metamorphism, and during the waning phases of the Isan Orogeny. Mineralisation was broadly synchronous with emplacement of voluminous phases of the Williams and Naraku batholiths (ca. 1550 - 1500 Ma) and widespread brecciation and accompanying metasomatism. Brecciation and metasomatism were best developed within Cover Sequence 2 stratigraphy, and in particular within calc-silicate rock and meta-siltstone stratigraphy of the Corella Formation, the predominant rocks of the Mary Kathleen Group. The geometry and distribution of brecciation in the Corella Formation was in part controlled by retrograde buckle folding imposed on a heterogeneous rock sequence that was fractured and boudinaged both pre- and syn-buckle folding. Brecciation is far more widespread in the Cloncurry District relative to the MKFB, reflecting in part a larger proportion of stratigraphy in the Cloncurry District that was at low angles to the shortening direction during the waning phases of the Isan Orogeny, favoring refolding and consequent fracturing. Variations in regional structural trends reflect strain partitioning around competent intrusive bodies, fault reactivation and refolding. Other contributing factors for brecciation include low temperature conditions during late deformation, and the proximity to voluminous intrusions, the emplacement of which likely resulted in transient elevated fluid pressure and strain rates, favoring fracturing and brecciation. The relative paucity of brecciation in most stratigraphic units outside of the Corella Formation reflects a high proportion of incompetent stratigraphy in these sequences (e.g. voluminous micaceous schists within the Soldiers Cap Group), which were able to• accommodate strain by plastic flow. The broad-scale geometry of the Cloncurry District reflects Cover Sequence 3 rocks overlying Cover Sequence 2 rocks, the two sequences being separated by early faults. Marbles within the Corella Formation, and schists in other stratigraphic sequences were not prone to brittle failure, and acted as low permeability barriers to fluid flow. These horizons allowed for the attainment of elevated fluid pressures within large volumes of brecciated rock. During the final stages of brecciation, these low competence marbles and schists were fractured and brecciated, predominantly within discrete fault zones. This shift from widespread brittle-ductile to purely brittle deformation likely reflects progressive cooling, as well as locally elevated fluid pressure and/or strain rate associated with pluton emplacement and degassing. A synchronous district-scale shift from compression to transtension facilitated the development of vertically continuous zones of dilation within faults, resulting in very large fluid pressure gradients and catastrophic fault valving. Brecciation was accompanied by widespread metasomatism that ranges from high temperature (400° - 600°C) Na-(Ca)-rich assemblages (e.g. albite ± actinolite, clinopyroxene, scapolite, magnetite, titanite, etc.) to retrograde (<400°C) chloritic assemblages. Interpretation of stable (0 and C) and radiogenic (Sr) isotopes and mineral chemistry is consistent with this spectrum of alteration assemblages reflecting metasomatic fluids of two predominant origins. The oxygen and carbon isotopic signature of carbonates from Na-(Ca) assemblages indicates that fluids responsible for this style of alteration were not simply equilibrated with magmatic rocks, but were exsolved from crystallizing plutons. Low temperature, low salinity fluids of inferred meteoric origin were introduced late in the paragenesis, and do not appear to have contributed significantly to the mass budgets of eu-Au ore systems in the district. Extensive fluid-wallrock interaction prior to mineralisation appears to have been important in the genesis of some deposits that record K- and Fe-rich alteration haloes, including for example the Ernest Henry deposit. However, the occurrence of skarn-like, intrusion-proximal mineralisation that lacks significant K- and Fe enrichment at for example Mt Elliott, indicates that fluid-wallrock interaction was not a necessary precursor for all styles of Cu-Au mineralisation in the Cloncurry District.

The Río Blanco–Los Bronces (Chile) is one of the richest endowed porphyry copper-molybdenum districts worldwide, where about 20% of the known mineralization is hosted by tourmaline-cemented hydrothermal breccia. This work seeks: (1) to find a relationship between tourmaline chemical and/or isotopic composition and the degree of mineralization in the breccia, (2) to constrain the source of the mineralizing fluid in the breccia, and (3) to determine of the composition and age of intrusive units in three new exploration projects and correlate them with the known intrusive rocks of the mine areas. Tourmaline from mineralized and barren breccias has similar boron isotopic compositions but differences in Mg/(Mg+Fe) ratios, Al-contents and Al-Fe correlation, which may have exploration value. Boron and sulfur isotopes results are consistent with a magmatic source of hydrothermal fluids. Results of whole rock geochemistry and U-Pb and 40Ar/39Ar geochronology of intrusive units, breccia and late-stage veins are combined with previous U-Pb, Ar/Ar and Re-Os ages to elucidate the magmatic and hydrothermal history of the district.:1 Introduction 1.1 Motivation of the study and statement of research questions 1.2 Scope of the study 2 Porphyry copper deposits (PCDs) 2.1 Introduction 2.1.1 Global copper inventory 2.1.2 Definition and classification of PCDs 2.2 Regional scale characteristics of PCDs 2.2.1 Tectonic setting 2.2.2 Space and time distribution 2.2.3 Porphyry stocks and their pluton and volcanic connections 2.2.4 Wall-rock Influence 2.3 Deposit-scale characteristics 2.3.1 Porphyry stocks and dikes 2.3.2 Hydrothermal breccia 2.3.3 Alteration-mineralization zoning 2.4 Processes of PCD formation 2.4.1 Arc magmatism 2.4.2 Magmatic volatiles 2.4.3 Genetic models 3 Regional setting of the study area 3.1 Tectono-magmatic setting 3.2 Metallogenic belts 4 Río Blanco – Los Bronces mining district 4.1 Mining history 4.2 District geology 4.2.1 Stratified rocks 4.2.2 Plutonic and hypabyssal intrusions 4.2.3 Structures 4.2.4 Alteration and mineralization 4.2.1 Geochronology database 5 Results 5.1 Plutonic units 5.1.1 Petrography 5.1.2 Whole rock (WR) geochemistry 5.1.3 Geochronology 5.2 Mineralization 5.2.1 Petrography 5.2.2 Tourmaline occurrence and composition 5.2.3 Sulfides and sulfates 6 Discussion 6.1 Time-space relationships of intrusion, brecciation and hydrothermal alteration 6.2 Stable isotope constraints on fluid source and evolution 6.2.1 Oxygen, hydrogen and sulfur isotopes 6.2.2 Boron isotopes 6.3 Tourmaline as a redox indicator and significance for exploration 7 Summary and conclusions 8 References Digital supplement Appendix (Methods) 9 Appendix Methods 9.1 Optical microscopy (OM) 9.2 Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) 9.3 Whole rock chemical analysis 9.4 Electron microprobe analyses (EMPA) 9.5 Boron isotopes 9.6 Sulfur isotopes 9.7 40Ar/39Ar dating 9.8 Zircon separation and characterization 9.9 U-Pb zircon LA-ICP-MS dating 9.10 U-Pb zircon CA-ID-TIMS dating 9.11 Single zircon evaporation as screening method