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Weis, Franz. "Oxygen Isotope Signatures of the Apatite-Iron Oxide Ore at Grängesberg." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173031.
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The origin of apatite iron oxide ores, like the deposit at Grängesberg in the Bergslagen mining district, has been a subject of much discussion through the years. Some support a formation by hydrothermal fluids while others suggest that the ore is orthomagmatic, i.e. formed directly from a magma as suggested for the iron ore deposits of El Laco in Chile or the deposits in Kiruna, although also these two are still subjected to controversies. In 2009 sampling was done on drillcores through the Grängesberg ore. On these samples an oxygen isotope study on magnetite, quartz and whole rock samples from both the ore and its host rocks was conducted in order to obtain new knowledge about the ore forming processes. The data allowed modeling to simulate a possible origin by different magmas or hydrothermal fluids as well as a possible temperature of formation. In addition, the data set was compared to published oxygen isotope analyses of the possible magmatic iron ores of Kiruna and El Laco. The results of the Grängesberg analysis revealed that the ore in the area seems to have an origin from both magmatic and hydrothermal sources.
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Lindeberg, Tomas. "Indium Analysis and Small-scale Distribution in Sulphides from the Lindbom Prospect, Långban Area, Western Bergslagen Ore Province." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196479.
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Indium is extensively used in LCD screens and solar cells. It is mainly produced as a byproduct during ore processing. With ever increasing demand for indium and most of the production being restricted to a few countries new sources for indium are needed. In Sweden, the westernmost Bergslagen is the only area, which is known to exhibit minerals with essential indium. The indium mineralisations at Långban, the Linbom prospect, which are studied in this bachelor’s thesis show several trends. The most notable is the copper indium trend seen in sphalerite. A likely substitution based on similar ionic radii and charges is Cu1++ In3+ ↔ 2Zn2+.Usually when cassiterite is associated with similar polymetalic indium bearing mineralisations as at Långban there is also high concentrations in cassiterite. This has previously not observed in Sweden, however during this project concentrations were indeed found in cassiterite.
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Pacanovsky, Aaron James. "Petrology of Gold Ore-Bearing Carbonates of the Helen Zone, Cove Deposit, Lander County, Nevada." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398682471.
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Piché, Mathieu. "Synthèse géologique et métallogenique du camp minier de Matagami, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1991. http://theses.uqac.ca.
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Magnan, Martin. "La zone 87 du gisement d'or et de cuivre du lac Troilus : pétrographie et géochimie /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.
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Mekkaoui, Alaoui Moulay El Mustapha. "Caractérisation géochimique, pétrologique et métallogénique du gisement de sulfures massifs vocanogènes ANSIL /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.
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Andersson, Stefan. "Malmmikroskopering - en studie av sulfidmineral från Långbantrakten, Bergslagen, Sverige." Thesis, Uppsala universitet, Berggrundsgeologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169481.
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De sulfidgruvor belägna i Långbantrakten som studien behandlar ligger i den västra delen av Bergslagen utanför Filipstad i Värmlands län. Opaka mineral (malm) från två mindre mineraliseringar, Näset och Getberget, har studerats med malmmikroskop och mikrosond för att beskriva mineralogin i området. Båda områdena domineras av olika (Cu-Fe-Pb-Zn)-sulfider, i Näset av kopparkis (CuFeS2), blyglans (PbS) och zinkblände ((Zn,Fe)S) och i Getberget av blyglans, zinkblände, kubanit (CuFe2S3) och magnetkis (Fe1-xS). I Näset finns en del mindre frekventa mineral, två olika faser av Co-pentlandit (en nickelrik och en utan nickel), gedigen Sb och Bi, (Ni-Co)-sulfid, breithauptit (NiSb) och magnetkis. Kubanit är även ett viktigt mineral som speglar mineraliseringens bildning. I Getberget finns liknande mindre frekventa mineral, kopparkis, nickelrik Co-pentlandit, gedigen Bi och Sb, silverglans (Ag2S), breithauptit och magnetit (Fe3O4). En sen utfällning av kubanit har skett i båda områdena och visar att mineraliseringarna har genomgått en liknande bildning och det stämmer även in på mineralogin, som även den är likartad.The small sulphide mines, Näset and Getberget that have been investigated are located just outside the main mineralization of Långban, near the city of Filipstad in Värmland County. Opaque minerals have been studied in reflected light microscopy and with an electron microprobe analysis to describe the mineralogy. Both areas are dominated by various (Cu-Fe-Pb-Zn)-sulphides, Näset with chalcopyrite (CuFeS2), galena (PbS) and sphalerite ((Zn,Fe)S) and Getberget with, galena, sphalerite, cubanite (CuFe2S3) and pyrrhotite (Fe1-xS). The sulphides are also accompanied by various accessory minerals, in Näset by two different phases of Co-pentlandite (on rich in nickel and one without), native Sb and Bi, a (Ni-Co)-sulphide, breithauptite (NiSb) and pyrrhotite. Cubanite is also a very important mineral that reflects the formation of the mineralization. In Getberget there are similar accessory minerals, chalcopyrite, nickel rich Co-pentlandite, native Bi and Sb, acanthite (Ag2S), breithauptite and magnetite (Fe3O4). A late precipitation of cubanite has occurred in both areas, suggesting that the mineralizations has been formed in similar conditions. This also holds true when comparing the mineralogy, which also is similar.
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Blake, Kevin L. "The petrology, geochemistry and association to ore formation of the host rocks of the Kiirunavaara magnetite-apatite deposit, northern Sweden." Thesis, Cardiff University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321483.
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Stalder, Marcel. "Petrology and mineral chemistry of sulphide ores and associated metalliferous rocks of the Gamsberg Zn-Pb deposit, South Africa : implications for ore genesis and mineral exploration." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16072.
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Thesis (PhD)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The Gamsberg Zn-Pb deposit is a metamorphosed and multiply deformed sediment-hosted base metal deposit in the central Namaqua Province of South Africa. The deposit is hosted by the Bushmanland Group, a late Palaeoproterozoic (2000-1600 Ma) supracrustal succession of quartzite, metapelitic schist and interbedded metavolcanic rocks. Mineralisation occurs within the central part of the Gams Formation, a heterogeneous sequence of metamorphosed metalliferous sediments and fine-grained organic-rich shales. The ore horizon is subdivided into a lower unit of metapelite-hosted ore, an intermediate layer of phosphorite-hosted ore, and an upper unit of banded garnet-apatite ore. The ore body is enveloped by unmineralised silicate-, carbonate- and oxide-facies metalliferous rocks, which originally represented mixtures of Fe-Mn-rich hydrothermal precipitates, authigenic carbonate, and variable concentrations of detrital material. Based on mineralogical and geochemical characteristics, the metalliferous host rocks are subdivided into iron formations, coticules, Fe-Mn silicates, impure marbles and barite/Ba-rich quartzite. Minerals of the Gams Formation mostly represent solid solution between the Fe and Mn end-members of garnet, pyroxene, pyroxenoid, amphibole, olivine, spinel and ilmenite. Calcium-rich rock types are a typical feature and characterized by the occurrence of manganoan calcite, clinopyroxene, andradite-rich garnet and titanite. A successive increase in the (Mn+Ca):Fe value of rocks and minerals is evident with increasing distance from the ore horizon. Amphibole is restricted to Fe-rich ore-bearing assemblages, whereas orthopyroxene, clinopyroxene, Fe-rich pyroxenoid and olivine are present in intermediate assemblages, and Mn-rich rhodonite and pyroxmangite in the most manganiferous assemblages. These variations are mimicked by an increase in the Mn:Fe value of coexisting garnet and ilmenite group minerals with increasing distance from ore. LA-ICP-MS analyses have been used to constrain the REE patterns of garnet and apatite. In the ore-body, these minerals display a positive Eu anomaly, which is interpreted to reflect a distinct hydrothermal signature. In contrast, garnet and apatite in unmineralised metalliferous rocks display nil or a negative Eu anomaly. Primary features of the Gams Formation, such as REE patterns, the banded nature of garnet-apatite ore, the presence of diagenetic apatite nodules, and the distribution of the redox-sensitive elements Ba and Mn have been used to constrain palaeo-environmental conditions. The results indicate that metapelitehosted ore has been deposited in a stratified ocean that was characterised by anoxic bottom waters and precipitation of Fe and Zn sulphides into organic matter-rich shales. These rocks were superceded by phosphorite-hosted ore, garnet-apatite ore and metalliferous host rocks that developed in a suboxic to oxic environment. The large size of the deposit, the internal lamination of the ores and the predominance of sphalerite and barite are consistent with a vent-distal setting and precipitation of the ore-forming constituents from dense and reduced hydrothermal fluids, which originated due to reactivation of dormant growth faults. Collectively, the geological evidence indicates that Gamsberg is bridging the gap betweenthe SEDEX and BHT classifications. The relationships demonstrate that differences between these two classes of sediment-hosted Zn-Pb deposits are predominantly related to environmental conditions within localised third order basins and not to fundamental differences in ore-forming processes.
AFRIKAANSE OPSOMMING: Die Gamsberg Zn-Pb afsetting is ‘n meerfasig vervormde en gemetamorfiseerde sedimentgesetelde onedel metaal afsetting in die sentrale Namakwa Provinsie van Suid Afrika. Die afsetting word geherberg deur die Boesmanland Groep, ‘n laat Paleoproterosoïse (2000 – 1600 Ma) bokors-opeenvolging van kwartsiet, metapelitiese skis en tussengelaagde metavulkaniese gesteente. Mineralisasie word gevind in the sentrale deel van die Gams Formasie. Die Gams Formasie is ‘n heterogene opeenvolging van gemetamorfiseerde metaalhoudende sediment en fynkorrelrige organiese skalie. Die erts horison word onderverdeel in ‘n onderste laag van metapeliet-gesetelde erts, n sentrale laag van fosforiet-gesetelde erts, en ‘n boonste laag van gebande granaat-apatiet erts. Die erts-liggaam word omhuls deur ongemineraliseerde silikaat-, karbonaat- en oksied-fasies metal-ryke rotse. Hierdie gesteentes word geinterpreteer as oorspronklike mengsels van Fe-Mn-ryke hidrotermale partikels, outigeniese karbonaat, en verskeie hoeveelhede detritale materiaal. Gebaseer op mineralogiese en geochemiese kenmerke word hierdie rotse onderverdeel in ysterformasies, „coticules“, Fe-Mn silikate, onsuiwer marmer en barite/Ba-ryke kwartsiet. Minerale van die Gams Formasie form meestal soliede oplossingsreekse tussen die Fe en Mn endlede van granaat, pirokseen, piroksenoid, amfibool, olivien, spinel en ilmeniet. Kalsium-ryke rots tipes is ‘n tipiese kenmerk van die Gams Formasie en word gekenmerk deur mangaan-ryke kalsiet, klinopirokseen, andradiet-ryke granaat en sfeen. Daar word ‘n stapsgewyse vergroting van die (Mn+Ca):Fe verhouding in gesteentes en minerale gevind met toeneemende afstand van die erts horison. Amfibool is beperk tot Fe-ryke ertsdraende gesteentes, ortopirokseen, klinopirokseen, Fe-ryke piroksenoid en olivien tot intermediêre gesteentes, en Mn-ryke rodoniet en piroksmangiet tot Mn-ryke gesteentes. Hierdie variasies gaan gepaard met vergroting van die Mn:Fe verhouding in granaat en ilmeniet-groep minerale met toeneemende afstand van die erts. LA-ICP-MS analises was gebruik om die skaars-aarde element patrone van granaat en apatiet te bepaal. In die erts-liggaam wys hierdie minerale ‘n positiewe Eu anomalie, wat geinterpreteerd word as ‘n hidrotermale kenmerk. In ongemineraliseerde gasheer gesteentes wys granaat en apatiet geen of ‘n negatiewe Eu anomalie. Primêre kenmerke van die Gams Formasie, soos skaars-aarde patrone, the gebande voorkoms van granaat-apatiet erts, die teenwoordigheid van diagenetiese apatiet knolle, en die verspreiding van die redox-sensitiewe elemente Ba en Mn, was gebruik om afleidings oor die paleo-omgewing te maak. Die resultate het gewys dat metapeliet-gesetelde erts afgeset was onder anoksiese bodem water deur presipitasie van Fe en Zn sulfiedes in organiese skalie. Hierdie erts gaan oor in fosforiet-gesetelde erts, granaat-apatiet erts en metaal-ryke gasheer gesteente wat in ‘n suboksiese tot oksiese omgewing ontstaan het. Die grootte van die afsetting, die interne gelaagdheid van die erts, asook die teenwoordigheid van sfaleriet en bariet dui op ‘n distale omgewing relatief tot die hidrotermale bron en presipitasie van die ertsuit digte en gereduseerde hidrotermale vloeistowwe, wat ontstaan het deur die heraktiveering van rustende groeiverskuiwings. Gesaamentlik bewys die geologiese kenmerke van Gamsberg dat gemetamorfiseerde SEDEX en Broken Hill-tipe mineralisasie binne die perke van ‘n enkele afsetting kan voorkom. Die geologiese verhoudings dui aan dat verskille tussen hierdie twee tipes van sedimentgesetelde afsettings meestal veroorsaak word deur omgewings-toestande binne in gelokaliseerde derde orde komme en nie deur fundamentele verskille in ertsvormende prosesse nie.
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Boucher, Stéphanie. "Ore Petrology and Alteration of the West Ansil Volcanic-hosted Massive Sulphide Deposit of the Noranda Mining Camp, Rouyn-Noranda, Quebec." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19786.
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The West Ansil deposit was the first Cu discovery in 25 years in the Noranda Central Camp. It has a combined indicated and inferred resource of ~1.2 Mt. Grades for the indicated resource are 3.4% Cu, 0.4% Zn, 1.4 g/t Au and 9.2 g/t Ag. The bulk of the resource is located in three massive sulphide lenses (Upper, Middle and Lower) that are entirely within the Rusty Ridge Formation above the Lewis exhalite. The mineralization in all three ore lenses consists of massive pyrrhotite + chalcopyrite + magnetite. Semi-massive sphalerite is restricted to the upper and lower parts of the Middle lens. Massive magnetite occurs at the center of the Upper and Middle lenses, where it replaces massive pyrrhotite. A striking feature of West Ansil is the presence of abundant colloform and nodular pyrite (+marcasite) in the massive sulphides. Late-stage replacement of massive pyrrhotite by colloform pyrite and marcasite, occurs mostly along the upper and lower contacts of the lenses.
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John, Kangeze Biteme. "Ore forming potential of the Atchiza Suite and Sustainable management of mineral deposits in Mozambique : "Petrology, geochemistry and sustainable management of mineral deposits"." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for geologi og bergteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20380.
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Part 1- Abstract This research study presents detailed petrographic- and geochemical- analysis of 63 rock samples from the Atchiza Suite. The Suite is a layered mafic-ultramafic pluton located in the Tete Suite, of NW Mozambique. At present, the Atchiza comprises a group of three main types of rock that are classified based on their mineralogy, textures, geochemical composition. These are ultramafic cumulates (dunite and pyroxenites), mafic cumulates (medium-grained cumulate gabbro) and coarse-grained gabbro (non-cumulate gabbro). Compared to the rest of other rocks, coarse-grained gabbro shows high enrichment of Ti (0.64-3.46 wt% TiO2), Zr (5.9-296.1 5ppm), Sr (253.7-1268.4ppm) and V (224-952.3ppm), but relatively low depleted in compatible elements (Ni = 48.7-235.7ppm , Cr = below detection limit to 410.5ppm). Cumulate ultramafics are highly enriched in compatible elements (Ni up to 4636.2ppm, Cr up to 4721ppm). A high Mg# in ultramafic cumulates (0.59-0.86) suggests an Mg-rich primitive parental magma, whereas a low Mg# in coarse-grained gabbro (0.23-0.37) suggests a relatively high-differentiated magma. Cumulate gabbro shows Mg# ranging from 0.40-0.72, suggesting a moderately evolved magma source (derivative magma subsequent to fractionation of ultramafic cumulates). The Ni/Zr, Cr/Zr, Sr/Zr and Ti/Zr ratios are generally the lowest in coarse-grained gabbro when compared to cumulate rocks. The same applied; this suggests that coarse-grained gabbros were probably formed from a relatively high-differentiated magmatic liquid. In addition, the presence of an uninterrupted cryptic differentiation trend with these ratios implies that the Atchiza igneous lithologies were derived from one and the same parental melt. Apparently, Atchiza shows great variability of Fe2O3, SiO2 and SO3 during magmatic differentiation. There is significant decrease in Fe2O3, an increased SiO2 and SO3 contents in residual magma during progressive magma fractionation. It is true that all these geochemical changes will lower down the solubility of S in the system, thus providing a favourable condition for silicate-sulfide immiscibility. Theoretically, therefore, the Atchiza may have a potential to host Ni-Cu-(PGE) sulfide deposits. Part 2- Abstract Unlike water and forests, minerals are finite resources; they cannot be replaced back to their natural forms once they are depleted. For that reason, sustainable management of mineral resources is very important so that stakeholders in the extractive sector are guaranteed the same opportunities in sharing benefits. As part of this study, and with respect to Atchiza Suite, this section is discussing sustainable management of mineral deposits in Mozambique. Investment in Mozambican extractive industry should primarily be done with the main objective of poverty reduction for Mozambican citizens. Thus, the Mozambican Government needs to realize that proper management of mineral deposits will provide sufficient income for the country, enough to fund other development projects. Rather than being mismanaged, this massive collection of mineral revenues needs to be appropriately re-invested back to diversify other economic sectors. If this mineral revenue is managed wisely, the national annual budgets will be sufficiently supported. Most importantly, the country’s reliance on international loans and aids will be reduced significantly. Decision-making for development of the country’s mineral projects should not be central-governed; rather it should be transparent to the public and open for opinions and suggestions. As the main stakeholder in Mozambican extractive sector, local communities and civil societal groups should also be given opportunities to participate in decision-making, important for the development of mining projects. Mineral agreements for which the Mozambican State has been signing with multinational companies for development of the country’s mineral projects need to be published and be available publicly. In addition, negotiation of mining agreements must be transparent and involve all stakeholders. Investment and development of the country’s mineral projects must be performed through partnerships and Joint ventures between multinational mining companies, national-based companies and the Mozambican State. Development of mineral deposits must incorporate environmental sustainability. Despite its high mineral potential (e.g. Ni-Cu-PGE-Ti-V), Atchiza also is surrounded by a wide range of other natural resources. The Cahora Bassa Dam, which is located just adjacent to Atchiza Project, is the main source of clean energy not only for Mozambique domestic market, but also for the majority of Sub-Saharan countries. All of these natural resources require good practice of Environmental sustainability in mining activities.
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Green, Bradley. "A study of the Wilkins and Green and Gold Copper-gold prospects, Olary Block, South Australia with emphasis on petrology, geochemistry and ore mineralogy /." Title page, contents and abstracts only, 1996. http://web4.library.adelaide.edu.au/theses/09SB/09sbg811.pdf.
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Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1998.Australian National Grid Reference (SI 54-2) 1:250 000. Four folded maps in pocket pasted onto back cover. Includes bibliographical references (leaves 62-68).
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Michaud, Michael Julien. "The geology, petrology, geochemistry and platinum-group element-gold-copper-nickel ore assemblage of the Roby Zone, Lac des Iles mafic-ultramafic Complex, northwestern Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0027/MQ52068.pdf.
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Polteau, Stéphane. "The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1007612.
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The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.
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Ferraina, Clément. "Partage des métaux entre liquide sulfuré et liquide silicaté : Expérimentation, modélisation et applications aux gisements de sulfures magmatiques." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2004/document.
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Comprendre l’enrichissement des liquides sulfurés en éléments chalcophiles et sidérophiles pouvantmener à la formation de gisements de sulfures magmatiques.Le premier objectif de cette thèse a été de quantifier les variations des coefficients de partage (Dsul/sil)de Co, Ni, Cu, Pd, Ag, Pt et Au dans des conditions crustales typiques des intrusions de la région deNoril’sk-Talnakh (Russie), par le biais d’une étude expérimentale en autoclave à chauffage interne,effectuée à 1200 °C, 70 MPa, sous différentes fugacités d’oxygène.Les résultats montrent que les Dsul/sil de Pd, Ag, Pt et Au augmentent avec la teneur de ces élémentsdans le liquide sulfuré, indiquant qu’ils ne suivent pas la loi de Henry, au contraire de ceux de Co, Ni, etCu. Ces Dsul/sil permettent de reproduire les teneurs en métaux des sulfures naturels de la région deNoril’sk, à partir d’un magma parent plus enrichi en Pd et Pt que les laves de la région, et en invoquantl’interaction entre des masses de liquide silicaté et de liquide sulfuré pour pouvoir enrichir ce dernier(facteur R entre 300 et 1000 pour les sulfures massifs et entre 300 et 6000 pour les disséminés).Le second objectif de cette thèse a été de modéliser, par une approche thermodynamique, les variationsdes Dsul/sil en fonction des conditions magmatiques. Ce modèle décrit les variations des Dsul/sil avec latempérature, la pression, la fugacité d’oxygène et la chimie des liquides, et suggère que les magmasmafiques à l’équilibre avec les liquides sulfurés les plus enrichis sont ceux qui ont les plus faiblestempératures et pressions, et les fugacités d’oxygène les plus élevéesA comprehensive knowledge of metal partitioning between sulfide liquid and silicate melt is essential tounderstand sulfide liquid enrichment in chalcophile and siderophile elements that can lead to theformation of magmatic sulfide ore deposits.The first aim of this thesis was to quantify the partition coefficients (Dsul/sil) for Co, Ni, Cu, Pd, Ag, Pt andAu at crustal conditions relevant to the Noril’sk-Talnakh region (Russia), through an experimental studyconducted in internal heated pressure vessels at 1200 °C, 70 MPa, and under variable oxygenfugacities.Our results show that Dsul/sil for Pd, Ag, Pt and Au increase with the content of the element in the sulfideliquid, showing that they do not follow Henry’s law, in contrast to those for Co, Ni, and Cu. These Dsul/silcan reproduce the metal contents of natural sulfides of the Noril’sk region, starting from a parent magmaPd- and Pt-richer than the lavas of the region, and invoking an interaction between the masses of silicateliquid and sulfide liquid in order to enrich the latter.The second objective of this thesis was to model Dsul/sil variations as a function of magmatic conditions,using a thermodynamic approach. This modeling allows investigating the variations of Dsul/sil withtemperature, pressure, oxygen fugacity and the compositions of both liquids and suggests that the maficmagmas with the lowest temperatures and pressures and the highest oxygen fugacities are those inequilibrium with the most enriched sulfide liquid
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Taylor, Mackenzie C. "GOLD FROM THE TYPE 4 ORE OF ROUND MOUNTAIN, NEVADA: A TEXTURAL AND MINERALOGICAL STUDY OF MACROCRYSTALLINE GOLD VS. DISSEMINATED GOLD." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1512407677037903.
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Pazeto, Abiliane de Andrade [UNESP]. "Correlação entre propriedades petrográficas e comportamento tecnológico e de alterabilidade das rochas ornamentais silicáticas Diamante Negro (BA), Ocre Itabira e Banco Galaxy (ES)." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92883.
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pazeto_aa_me_rcla.pdf: 2444516 bytes, checksum: 35703d25545452a56889da24605468b1 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
O objetivo da presente pesquisa foi estabelecer a correlação entre as propriedades petrográficas e o comportamento tecnológico e de alterabilidade de três materiais utilizados como rochas ornamentais e para revestimento. Os tipos petrográficos correspondem a um microgabro (Diamante Negro), um hornblenda sienito pórfiro com quartzo (Ocre Itabira) e um granito pegmatóide com granada e sillimanita (Branco Galaxy), sendo o primeiro proveniente do estado da Bahia e os dois últimos do estado do Espírito Santo. Os materiais foram caracterizados petrograficamente e submetidos a uma bateria de ensaios físico-mecânicos e de alteração acelerada que compreenderam determinações de índices físicos, desgaste abrasivo Amsler, compressão uniaxial simples, resistência à flexão 3 e 4 pontos, impacto de corpo duro, velocidade de propagação de ondas ultrassônicas longitudinais, coeficiente de dilatação térmica linear e resistência ao ataque químico sob efeito de compostos agressivos e em câmaras saturadas em atmosfera salina e dióxido de enxofre (SO2). Os resultados demonstram que o comportamento tecnológico das rochas está intrinsecamente relacionado aos aspectos mineralógicos, estruturais e texturais inerentes a cada tipo petrográfico. O Diamante Negro é o material detentor dos maiores índices físico-mecânicos, uma vez que suas características petrográficas são marcadas por granulação fina, bom entrelaçamento mineral, e baixo grau de microfissuramento. Quanto à alteração acelerada, no entanto, apresentou variações cromáticas consideráveis, dado seu elevado teor de minerais máficos. O tipo comercial Ocre Itabira também apresentou boas propriedades tecnológicas, com valores inferiores ao Diamante Negro devido principalmente à sua granulação...
The objective of this research was correlating petrographical properties to the technological and alterability behavior of three materials used as ornamental and building stones. The samples correspond to a microgabbro (Diamante Negro), a hornblende porphiral syenite with quartz and (Ocre Itabira) a pegmatoid granite with garnet and sillimanite (Branco Galaxy), being the first sample originating from the Bahia state and the last one from Espírito Santo state. The materials were petrographically analyzed and submitted to physical mechanics tests and chemical alterability including measurements of physical indexes, abrasion resistance, compressive strength, modulus of rupture, flexural strength, impact strength, ultrasonic pulse velocity, linear thermal expansion coefficient and resistance to the chemical attack accomplished by aggressive compositions and chambers which simulate both sea-salt and sulphur dioxide weathering. The results reveal the influence of minerals, textural and structural features over the studied stones behavior during the performed tests. Diamante Negro is the material which showed the highest physical-mechanics properties, once their petrographical parameters correspond to fine grain size, good mineral interlacement, and low microcrack degree. However, relating to the chemical alterability it showed considerable chromatic deterioration, given its high content of mafic minerals. The commercial type Ocre Itabira also presented good technological properties, with inferior values than Diamante Negro due to its large grain size granulation and high degree of relative microcracking. The brownish coloration of potash feldspars porphyries present in its mineralogical composition turned the effects caused by the chemical reagents less evident. In general, Branco Galaxy presented the smallest values of... (Complete abstract click electronic access below)
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Pazeto, Abiliane de Andrade. "Correlação entre propriedades petrográficas e comportamento tecnológico e de alterabilidade das rochas ornamentais silicáticas Diamante Negro (BA), Ocre Itabira e Banco Galaxy (ES) /." Rio Claro : [s.n.], 2011. http://hdl.handle.net/11449/92883.
Full textAbstract:
Orientador: Antonio Carlos ArturBanca: Tamar Milca Bortolozzo Galembeck
Banca: Fabiano Cabañas Navarro
Resumo: O objetivo da presente pesquisa foi estabelecer a correlação entre as propriedades petrográficas e o comportamento tecnológico e de alterabilidade de três materiais utilizados como rochas ornamentais e para revestimento. Os tipos petrográficos correspondem a um microgabro (Diamante Negro), um hornblenda sienito pórfiro com quartzo (Ocre Itabira) e um granito pegmatóide com granada e sillimanita (Branco Galaxy), sendo o primeiro proveniente do estado da Bahia e os dois últimos do estado do Espírito Santo. Os materiais foram caracterizados petrograficamente e submetidos a uma bateria de ensaios físico-mecânicos e de alteração acelerada que compreenderam determinações de índices físicos, desgaste abrasivo Amsler, compressão uniaxial simples, resistência à flexão 3 e 4 pontos, impacto de corpo duro, velocidade de propagação de ondas ultrassônicas longitudinais, coeficiente de dilatação térmica linear e resistência ao ataque químico sob efeito de compostos agressivos e em câmaras saturadas em atmosfera salina e dióxido de enxofre (SO2). Os resultados demonstram que o comportamento tecnológico das rochas está intrinsecamente relacionado aos aspectos mineralógicos, estruturais e texturais inerentes a cada tipo petrográfico. O Diamante Negro é o material detentor dos maiores índices físico-mecânicos, uma vez que suas características petrográficas são marcadas por granulação fina, bom entrelaçamento mineral, e baixo grau de microfissuramento. Quanto à alteração acelerada, no entanto, apresentou variações cromáticas consideráveis, dado seu elevado teor de minerais máficos. O tipo comercial Ocre Itabira também apresentou boas propriedades tecnológicas, com valores inferiores ao Diamante Negro devido principalmente à sua granulação... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of this research was correlating petrographical properties to the technological and alterability behavior of three materials used as ornamental and building stones. The samples correspond to a microgabbro (Diamante Negro), a hornblende porphiral syenite with quartz and (Ocre Itabira) a pegmatoid granite with garnet and sillimanite (Branco Galaxy), being the first sample originating from the Bahia state and the last one from Espírito Santo state. The materials were petrographically analyzed and submitted to physical mechanics tests and chemical alterability including measurements of physical indexes, abrasion resistance, compressive strength, modulus of rupture, flexural strength, impact strength, ultrasonic pulse velocity, linear thermal expansion coefficient and resistance to the chemical attack accomplished by aggressive compositions and chambers which simulate both sea-salt and sulphur dioxide weathering. The results reveal the influence of minerals, textural and structural features over the studied stones behavior during the performed tests. Diamante Negro is the material which showed the highest physical-mechanics properties, once their petrographical parameters correspond to fine grain size, good mineral interlacement, and low microcrack degree. However, relating to the chemical alterability it showed considerable chromatic deterioration, given its high content of mafic minerals. The commercial type Ocre Itabira also presented good technological properties, with inferior values than Diamante Negro due to its large grain size granulation and high degree of relative microcracking. The brownish coloration of potash feldspars porphyries present in its mineralogical composition turned the effects caused by the chemical reagents less evident. In general, Branco Galaxy presented the smallest values of... (Complete abstract click electronic access below)
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Giacomeli, Henrique [UNESP]. "As formações ferríferas bandadas de Piumhi: geologia, petrografia e caracterização tecnológica." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92927.
Full textAbstract:
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giacomeli_h_me_rcla.pdf: 2382791 bytes, checksum: ff9cf032666f2762cd125724e4e53d8b (MD5)As formações ferríferas bandadas de Piumhi pertencem ao Grupo Lavapés, definido como uma seqüência metassedimentar alóctone do tipo melange tectônica de idade mínima de 634 +/-07. Essas formações ferríferas afloram ao longo da serra do Lavapés, interdigitadas em sucessão de metaconglomerados poli- a oligomíticos, metagrauvacas finas e quartzo-muscovita xistos, que pertencem a Unidade Conglomerática, e, de forma mais contínua, no contato desta unidade com a sobrejacente, a qual é composta por sericita quartzito, definida neste trabalho como Unidade Quartzítica. Dados obtidos no presente trabalho mostram que a deposição dessas formações ferríferas se iniciou num ambiente sedimentar de alta energia, do tipo continental a transicional gradando para bacia marinha restrita, dentro da qual ocorreram pulsos de sedimentação progradante, sucedida de retrograndante e, posteriormente, nova sequência progradante. Nas formações ferríferas estudadas os minerais opacos são representados essencialmente por hematita do tipo granular e especular, magnetita e martita, que ocorrem em bandas de espessura submilimétrica a centimétrica intercaladas com bandas de quartzo recristalizado; muscovita e filossilicatos finos ocorrem subordinadamente. Apresentam foliação milonítica e estão metamorfisadas em fácies xisto verde, sendo que a martitização de algumas amostras, em estágio avançado de transformação mineralógica, revela a presença de fluidos metamórficos tardios de natureza oxidante. Critérios mineralógicos e texturais permitiram definir três tipos de minério: semi-friável, compacto e maciço. Os cristais de especularita e magnetita/martita ocorrem numa faixa granulométrica de 5 a 450μm, com predomínio de cristais com tamanho médio de 40μm, que muitas vezes estão interpenetrados...
The banded iron formations of the Piumhi belongs to the Lavapés Group, defined by a sequence of metasedimentary allochthonous tectonic mélange yielding a minimum age 634 + / -07. These iron formations outcrop around of the Lavapés Montain, interlayered in succession in the metaconglomerates poly- to oligomíticos, metagraywacke, quartz-muscovite schists, and more continuously in contact with the overlying unit, which is composed of the sericite quartzite, defined Unit quartzite. Data obtained in this study show that the deposition iron formations started from sedimentary high energy environment like transitional continental to restricted marine basin, which occurred within the progradational pulses of the sedimentation, followed by retrogranding and then new sequence prograding. The opaque minerals of the Piumhi Banded Iron Formations are mainly represented by hematite and specular-type granules, magnetite and martite, which occur in bands interlayed by submillimeter to centimeter beds of the recrystallized quartz, muscovite and subordinate phyllosilicates occur fine. Exhibit mylonitic foliation and are metamorphosed into greenschist facies, and the martitization some samples, in advanced stages of mineralogical transformation, reveals the presence of metamorphic fluids late in the oxidizing nature. Mineralogical and textural criteria allowed to define three ores types: semi-friable, compact and massive The crystals of magnetite and specularite / martite occur at grain size range from 5 to 450μm, with a predominance of crystals with size average of 40μm, which often are interpenetrated with quartz. Given these peculiarities, the tests of processing such as grinding, sieving and magnetic separation show that the types and semi-friable compact exhibit similar behavior. Since the procedures used in... (Complete abstract click electronic access below)
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Saad, Allan Emile. "A petrological study of the tin-tungsten deposit at Renosterkop, Augrabies, Northern Cape Province / by Allan Emile Saad." Thesis, Potchefstroom University for Christian Higher Education, 1987. http://hdl.handle.net/10394/606.
Full textAbstract:
Renosterkop is a large low grade tin-tungsten-zinc deposit located 85km
WSW of Upington in the northern Cape Province, South Africa. The
mineralization is hosted by a number of shallow-dipping, sheeted greisen
bodies that are surrounded by, and partly intercalated with a well foliated
granite gneiss country rock. The gneiss is taken to belong to the
intrusive Riemvasmaak gneiss of the Namaqualand Metamorphic Complex.
The mineralized host (referred to as TBQ) is a grey, homogeneous, fine
to medium grained rock composed predominantly of quartz, biotite and
topaz with minor amounts of fluorite and accessory opaque minerals,
zircon and secondary chlorite. The unmineralized granite gneiss country
rock is medium-to coarse-grained, pinkish in colour and composed
primarily of microcline, plagioclase, quartz and biotite, with or without
hornblende. Rock types, transitional in mineralogy but with clearly
distinguishable contacts, are present between the TBQ and the granite
gneiss.
A prominent chemical and mineralogical halo, 20m to 50m wide, envelopes
the Renosterkop deposit. There is a gradational transition from an
unaltered hornblende biotite gneiss, through gneiss containing greenish-brown
biotite to an approximately 2 m wide transition zone, characterized
by the partial replacement of the greenish-brown biotite by chlorite.
The transition zone in turn yields to the TBQ in which reddish-brown
biotite forms at the expense of the chlorite, and topaz, quartz and
fluorite are formed at the expense of the feldspar. Major and trace
element analyses show a spectrum of chemical compositions with coherent
trends that support a gradational transition from the hornblende-bearing
granite gneiss, through the transitional rock types to the TBQ.
The mineralogical and chemical characteristics of the Renosterkop rock
types are consistent with an origin by progressive greisenization of a
"within plate" A- type granitoid host rock. A genetic model is proposed
which involves the formation of the TBQ greisen during intense
metasomatic alteration and replacement of the granite gneiss within a zone
of structural weakness that provided conduits for migrating, F-rich,
metal-bearing solutions, and thereby inherited the foliation and
structural features present in the original granite gneiss.Thesis (MSc)--PU vir CHO, 1987.
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Giacomeli, Henrique. "As formações ferríferas bandadas de Piumhi : geologia, petrografia e caracterização tecnológica /." Rio Claro : [s.n.], 2011. http://hdl.handle.net/11449/92927.
Full textAbstract:
Anexo 3 mapasOrientador: Antenor Zanardo
Banca: Afonso Schrank
Banca: Sebastião Gomes de Carvalho
Resumo: As formações ferríferas bandadas de Piumhi pertencem ao Grupo Lavapés, definido como uma seqüência metassedimentar alóctone do tipo melange tectônica de idade mínima de 634 +/-07. Essas formações ferríferas afloram ao longo da serra do Lavapés, interdigitadas em sucessão de metaconglomerados poli- a oligomíticos, metagrauvacas finas e quartzo-muscovita xistos, que pertencem a Unidade Conglomerática, e, de forma mais contínua, no contato desta unidade com a sobrejacente, a qual é composta por sericita quartzito, definida neste trabalho como Unidade Quartzítica. Dados obtidos no presente trabalho mostram que a deposição dessas formações ferríferas se iniciou num ambiente sedimentar de alta energia, do tipo continental a transicional gradando para bacia marinha restrita, dentro da qual ocorreram pulsos de sedimentação progradante, sucedida de retrograndante e, posteriormente, nova sequência progradante. Nas formações ferríferas estudadas os minerais opacos são representados essencialmente por hematita do tipo granular e especular, magnetita e martita, que ocorrem em bandas de espessura submilimétrica a centimétrica intercaladas com bandas de quartzo recristalizado; muscovita e filossilicatos finos ocorrem subordinadamente. Apresentam foliação milonítica e estão metamorfisadas em fácies xisto verde, sendo que a martitização de algumas amostras, em estágio avançado de transformação mineralógica, revela a presença de fluidos metamórficos tardios de natureza oxidante. Critérios mineralógicos e texturais permitiram definir três tipos de minério: semi-friável, compacto e maciço. Os cristais de especularita e magnetita/martita ocorrem numa faixa granulométrica de 5 a 450μm, com predomínio de cristais com tamanho médio de 40μm, que muitas vezes estão interpenetrados... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The banded iron formations of the Piumhi belongs to the Lavapés Group, defined by a sequence of metasedimentary allochthonous tectonic mélange yielding a minimum age 634 + / -07. These iron formations outcrop around of the Lavapés Montain, interlayered in succession in the metaconglomerates poly- to oligomíticos, metagraywacke, quartz-muscovite schists, and more continuously in contact with the overlying unit, which is composed of the sericite quartzite, defined Unit quartzite. Data obtained in this study show that the deposition iron formations started from sedimentary high energy environment like transitional continental to restricted marine basin, which occurred within the progradational pulses of the sedimentation, followed by retrogranding and then new sequence prograding. The opaque minerals of the Piumhi Banded Iron Formations are mainly represented by hematite and specular-type granules, magnetite and martite, which occur in bands interlayed by submillimeter to centimeter beds of the recrystallized quartz, muscovite and subordinate phyllosilicates occur fine. Exhibit mylonitic foliation and are metamorphosed into greenschist facies, and the martitization some samples, in advanced stages of mineralogical transformation, reveals the presence of metamorphic fluids late in the oxidizing nature. Mineralogical and textural criteria allowed to define three ores types: semi-friable, compact and massive The crystals of magnetite and specularite / martite occur at grain size range from 5 to 450μm, with a predominance of crystals with size average of 40μm, which often are interpenetrated with quartz. Given these peculiarities, the tests of processing such as grinding, sieving and magnetic separation show that the types and semi-friable compact exhibit similar behavior. Since the procedures used in... (Complete abstract click electronic access below)
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Phillips, David. "Mineralogy and petrology of the Townlands iron-rich ultramafic pegmatite." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1007617.
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The Townlands iron-rich ultramafic pegmatite is a relatively large pipelike body situated in the western corner of Rustenburg Section, Rustenburg Platinum Mines. It is characterised by a strong negative magnetic signature and transgresses the noritic layered sequence of the upper critical zone of the Bushveld Complex. The layered rocks are downwarped in the vicinity of the pipe and are in sharp contact with the pegmatitic material. The pegmatite varies in composition between dunite and wehrlite, with the marginal zones being more wehrlitic in composition. Olivine (Fo₃₀ - Fo₅₂) and clinopyroxene (Wo₄₅En₃₀Fs₂₅ - Wo₄₅En₃₇Fs₁₈) are the dominant constituents and accessory phases include ilmenite, Ti -magnetite, apatite, amphiboles, chlorite-group minerals, biotite, ilvaite and a host of unusual ore minerals. The Fe-Ti oxides exhibit exsolution textures typically found in slowly cooled igneous rocks and temperatures of formati on are consi dered to be in excess of 800°C. The UG2 chromitite leader layers intersected by borehole TLP.l are enriched in Fe and Ti and exhibit compositions intermediate between chromite and Ti-magnetite. The ore mineral assemblage includes a primary sulphide assemblage consisting of troilite, chalcopyrite, cubanite and pentlandite, and an array of unusual phases formed by late-stage secondary processes. The unusual sulphides mooihoekite and haycockite, that occur in certain parts of the pegmatite, are considered to have formed by partial replacement of the primary assemblage and a possible paragenetic sequence is discussed. Mineral compositions and whole rock geochemical data are consistent with an origin for the pegmatite by crystallization from a fractionated melt. It is suggested that intercumulus fluids, trapped during the crystallization of the noritic layered sequence, accumulated in an area of structural weakness, in response to an increasing overburden pressure and/or tectonic activity. Evidence is also presented that indicates that the Townlands pegmatite may consist of at least two separate, but adjoining pegmatite bodies.KMBT_363
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Jourdain, Vincent. "Géologie des amas sulfures aurifères de la province de Grenville /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.
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Thèse (D.R.Min.)-- Université du Québec à Chicoutimi.Programme offert à l'Université du Québec à Montréal en vertu d'un protocole d'entente avec l'Université du Québec à Chicoutimi. CaQCU Document électronique également accessible en format PDF. CaQCU
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Fredette, Julie. "Pétrographie, géochimie et potentiel économique en Fe-Ti-P du secteur du Lac à Paul, partie nord de la suite anorthositique de Lac-Saint-Jean, province de Grenville, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
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Thèse (M.Sc.T.) -- Université du Québec à Chicoutimi, 2006.La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en sciences de la terre. CaQCU Bibliogr.: f. 274-294. Document électronique également accessible en format PDF. CaQCU
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Manyeruke, Tawanda Darlington. "The petrography and geochemistry of the Platreef on the farm Townlands near Potgietersrus, northern Bushveld Complex." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-04282005-110052/.
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Lauzière, Kathleen. "Environnement géologique et minéralisation aurifère à la mine Bachelor, Desmaraisville, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1989. http://theses.uqac.ca.
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Bandyayera, Daniel. "Formation des latérites nickélifères et mode de distribution des éléments du groupe du platine dans les profils latéritiques du complexe de Musongati, Burundi /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1997. http://theses.uqac.ca.
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Wasilewski, Benjamin. "Geochronology, Petrogenesis and Crustal Evolution of the Saglek-Hebron Complex (Northern Labrador): Over One Billion Years of Archean Geological History." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39617.
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The Saglek-Hebron Complex (SHC) in Northern Labrador represents one of the oldest terrains on Earth and it is closely related to the Archean Itsaq Gneiss Complex (IGC) in Greenland. The SHC is a typical granite-greenstone terrain that recorded over one billion years of magmatic history between ~3900 Ma and ~2700 Ma. Our geochronological and geochemical study shows that the SHC includes five generations of trondhjemite-tonalite-granodiorite suites (TTG): the ~3870 Ma Iqaluk gneiss, the ~3750 Ma Uivak I gneiss, the ~3600 Ma Uivak II gneiss, the newly described ~3300 Ma Iluilik gneiss, and the ~3220 Ma Lister gneiss. These granitoid units are mostly consist of trondhjemite and tonalite with only rare granodiorites that appear to define a distinct unit formed at ~3330 Ma and newly defined as the Iluilik gneiss. The Iluilik granodiorite appears to be derived from a Hadean mafic crust as supported by its combined whole-rock geochemical composition, its positive µ142Nd value of +6, and its low εHf= -6 and εNd= -3, at 3300 Ma. SHC granites were emplaced throughout the Archean, from 3800 to 2700 Ma, but are predominant in the Neoarchean. They appear to have been mainly formed from the reworking of the SHC TTG, as supported by their low εHf and εNd initial values of respectively -16 and -11 at 2700 Ma. The granitoids include numerous enclaves of supracrustal rocks from various size, up to a few kilometers in scale, consisting of metavolcanic metasedimentary rocks. Previous work has suggested that they were formed at two different ages, with the younger Upernavik supracrustal unit deposited around 3400 Ma and the older Nulliak supracrustal assemblage deposited at around 3750 Ma. We show that both units are comparatively geochemically homogeneous with no distinction between the mafic and ultramafic rocks from both supracrustal assemblages. They mainly consist of mafic metavolcanic amphibolites with tholeiitic affinities, consistent with more depleted mafic and more enriched compositions produced by magmatic differentiation. Their complementary Eu anomaly and whole-rock geochemistry suggest that they formed from fractional crystallization of gabbroic assemblage that derived from similar if not the same parental magma. The mafic metavolcanic rocks are also often associated with ultramafic rocks that we divided into two distinct units, respectively referred as the high-Fe and the low-Fe ultramafic rocks, characterized by different FeO contents and Al/Ti ratio. They both represent olivine-rich cumulative rocks derived from distinct parental komatiitic basalt magmas. Our interpretation contrasts with previous work suggesting that the SHC ultramafic rocks were komatiites and slivers of residual lithospheric mantle. Most SHC TTG exhibit a positive 142Nd anomaly, as high as µ142Nd = +15, suggesting a source formed by differentiation in the Hadean. This 142Nd isotopic composition is similar to the Nulliak supracrustal rocks that exhibit on average a µ142Nd of +10. TTG is generally considered to derive from a mafic precursor. This study therefore shows that mafic crustal source of the SHC Eoarchean TTG, potentially the Nulliak metabasalts, derives from an ancient highly depleted mantle, described as the Saglek mantle, sharing a similar early history as the mantle reservoir involved in the formation of the ancient Itsaq terrane of southwest Greenland. The Saglek depleted mantle is interpreted to have formed at ~4400 Ma, exhibit highly depleted signature with a 147Sm/144Nd ratio of 0.221-0.240.
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Dubé, Benoît. "Métallogénie aurifère du filon-couche de Bourbeau : région de Chibougamau, Quebec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1990. http://theses.uqac.ca.
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Champagne, Patrick. "Géochimie de l'indice aurifère Erratix, Chibougamau /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1989. http://theses.uqac.ca.
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Chaker, Mohammed. "Géochimie et métallogénie de la mine d'or de Tiouit, anti-atlas oriental, sud du Maroc /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1997. http://theses.uqac.ca.
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Mercier-Langevin, Patrick. "Les minéralisations aurifères au sein de la tonalite de La Grande-Sud, Baie-James, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2000. http://theses.uqac.ca.
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Tremblay, Christian. "Les éléments du groupe du Platine dans le dyke de Méquillon ceinture de Cape-Smith, Nouveau-Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1990. http://theses.uqac.ca.
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Côté, Carol. "La distribution de l'or à la mine Montauban /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1989. http://theses.uqac.ca.
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Prud'homme, Nathalie. "Caractérisation pétrographique et géochimique de la carbonatite et de la syénite de la mine Lac Shortt /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1990. http://theses.uqac.ca.
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Mémoire (M.Sc.T.)--Université du Québec à Chicoutimi, 1990."Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en sciences de la terre" CaQCU Document électronique également accessible en format PDF. CaQCU
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Terracin, Matthew Theodore. "Petrography, geochemistry and origin of atypical sedimentary-igneous contact relationships at the base of the Hotazel Formation around Middelplaats, Northern Cape Province, RSA." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1012985.
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In the Middelplaats mine area of the Kalahari manganese field, two drill holes (MP53 and MP54) intersected anomalously high-grade manganese ore sitting stratigraphically just above an igneous body (likely a dike or sill). Manganese ore located within approximate 5 meters of the contact with the underlying igneous rocks has been substantially metasomatically upgraded from 25 percent manganese, to over 40 percent whilst the dominant manganese species within the ore has been altered to hausmannite. This report demonstrates the metasomatic alteration is related to devolatilization (removal and/or remobilization of H₂O, CO₂ and CaO) due to contact metamorphism caused by the underlying igneous rocks. The Middelplaats mine is situated in the southwest corner of the Kalahari manganese field where the paleo basin shallows out and ends. Within the mine area, several stratigraphic units pinch out or are truncated by the side of the basin. This pinching out of lithological formations has led to the underlying Ongeluk Formation being in contact with the much younger units of the Hotazel Formation. Therefore, geochemical investigation into the nature and source of the igneous rocks was also undertaken to see if the rocks from the two drill holes were related to one another and/or the underlying Ongeluk Formation. Results of these geochemical studies have demonstrated that the Middelplaats igneous rocks (dolerites) from the two drill holes (MP53 and MP54) share a co-genetic source region. There is also reasonable geochemical evidence that the source region of the Middelplaats igneous rocks was substantially similar to the source region of the Ongeluk Formation. This may indicate that the source region of the Ongeluk Formation was reactivated at some later stage resulting in the emplacement of doleritic dikes or sills in the Middelplaats mine area. The Middelplaats igneous rocks were also found to have undergone a slight but pervasive potassic alteration; with most of the original plagioclase feldspar showing some level of replacement by a potassium enriched feldspar. Although no source for this potassic fluid was found, the devolatilization reaction within the manganese ore appears to have released some potassium into the surrounding rocks. This additional potassium may be responsible for some localized potassic alteration.
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Zhou, Yongzhang. "Géochimie et mécanisme métallogénique du district aurifère de Hetai, sud de la Chine = Geochimistry and metallogenetic mechanism of the Hetai gold field, southern China /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1992. http://theses.uqac.ca.
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Thèse (D.R.Min.) -- Université du Québec à Chicoutimi, 1992.These présentée en collaboration de l'Université du Québec à Chicoutimi et Institute of geochemistry, Academia Sinica. CaQCU Document électronique également accessible en format PDF. CaQCU
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Manyeruke, Tawanda Darlington. "Compositional and lithological variation of the Platreef on the farm Nonnenwerth, northern lobe of the Bushveld Complex implications for the origin of platinum-group elements (PGE) mineralization /." Thesis, Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01192009-164657/.
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Georgiou, Elena. "Geologie, petrologie et petrochimie du complexe plutonique de la foret d'akapnou, chypre, et des gites de chromite associes." Orléans, 1987. http://www.theses.fr/1987ORLE2033.
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L'etude cartographique en depit d'un tectonique complexe, a permis d'observer de bas en haut: sequence mantelique (harzburgites a enclaves dunitiques); sequence cumulative (dunite principale, plastiquement deformee, wchrlites, pyroxenites, gabbros et plangiogranites)
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Fairey, Brenton John. "Genesis of karst-hosted manganese ores of the Postmasburg Manganese Field, South Africa with emphasis on evidence for hydrothermal processes." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1020904.
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The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, once represented one of the largest sources of manganese ore worldwide. However, the discovery of the giant manganese deposits of the Kalahari Manganese Field (KMF) led to the gradual decline in manganese mining activity in the PMF. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes in ore formation and metasomatic alteration is not addressed. The identification of an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in the PMF ores studied in this thesis, is indicative of the influence of hydrothermal activity. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for the majority of samples analysed through bulk-rock techniques. The discovery of a Ba-Mn arsenate/vanadate similar to gamagarite may also indicate that the hydrothermal fluid affecting the ores was not only alkali-rich but also probably contained some As and V. The fluid was likely to be oxidized and alkaline in nature and is thought to have been a mature basinal brine. Various replacement textures, particularly of Na- and Krich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as oreminerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and the deviation of their character from the pigeon-hole-type classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. The discovery of hydrothermallydeposited alkali-rich assemblages in the PMF and KMF provides grounding for further investigation into a possible regional-scale hydrothermal event at least re-constituting the ores. Some shortcomings in previous works include disregard for the highly variable nature of the PMF deposits, the effects of hydrothermal activity of the ores and the existence of stratigraphic discrepancies. This study provides a single, broad model for the development of all manganese deposits of the PMF. The source of metals is attributed to all formations that stratigraphically overly the Reivilo Formation of the Campbellrand Subgroup (including the Reivilo Formation itself). The main process by which metals are accumulated is attributed to karstification of the dolomites. The interaction of oxidized, alkaline brines with the ores is considered and the overlying Asbestos Hills Subgroup BIF is suggested as a potential source of alkali metals.
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Ircañaupa, Acevedo Yber Juan. "Comportamiento de la mineralización de oro en el batolito de la costa, en la super unidad Santa Rosa, Chosica-Lima." Master's thesis, Universidad Nacional Mayor de San Marcos, 2017. https://hdl.handle.net/20.500.12672/7109.
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Determina el comportamiento de la mineralización del oro en rocas pertenecientes al Batolito de la costa, superunidad Santa Rosa, Chosica-Lima. La zona de estudio abarcó todo el distrito de Lurigancho-Chosica y de lo mapeado se deduce que más del 70% de rocas pertenecen a la Superunidad Santa Rosa de edad Cretácico superior (75-90 ma), diferenciándose la Superunidad Santa Rosa oscuro compuesto de dioritas-tonalitas y la Superunidad Santa Rosa claro de tonalitasgranodioritas. Las fracturas tienen un patrón general de dirección andina (NO-SE), donde la mineralización de oro y cobre se ha depositado La mineralización se concentra en dos zonas; la primera La Cantuta-9 de Octubre; que es más aurífera que cuprífera y la otra San AntonioCarossio; que es más cuprífera que aurífera. Esta mineralización se presenta en vetas de cuarzo-óxidos. Existe minería informal en el sector La Cantuta-9 de Octubre, que explota oro en óxidos, realizando socavones y procesando el mineral en la quebrada de California en quimbaletes. Los trabajos de campo abarcaron todo el distrito de Lurigancho-Chosica, llevando a cabo un mapeo geológico que contempló la toma de datos de las estructuras mineralizadas. Se describieron los tipos de rocas del área, recolectando muestras de mano y seleccionando algunas para un estudio petrográfico, la evaluación de las alteraciones hidrotermales fue muy importante para determinar si estas se hallan focalizadas a las estructuras o si es un comportamiento regional. Se dio énfasis a la mineralización y sus asociaciones, que nos sirvió para la recolección de muestras que posteriormente fueron seleccionadas, para un estudio mineragráfico. El estudio nos sirvió para determinar el comportamiento del oro en las estructuras mineralizadas de la superunidad Santa Rosa; sector Chosica, que se halla a nivel submicroscópico y para ubicar dichas estructuras en un modelo de depósito (Depósito hidrotermal asociado a intrusivos). El análisis químico de las muestras arroja un alto contenido de oro por zonas, siendo la más alentadora la zona de La Cantuta - 9 de Octubre.Tesis
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Healy, Raymond E. "Ore petrology and applied mineralogy of the Trout Lake massive sulfide deposit, Flin Flon, Manitoba." 1991. http://hdl.handle.net/1993/7212.
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The ore mineralogy of the Trout Lake massive sulfide deposit, Flin Flon, Manitoba has been investigated. Nine ore types are defined, of which seven form a differentiation series from the Zn-rich hangingwall ores to the Cu-rich footwall ores. The remaining two ore types are of tectonic origin. Two groups of elements: (1) the Zn-Group (Zn, Cd, Sb, Pb, Ag, Hg, In, Sn and As), and (2) the Cu-Group (Cu, Se, Te, Co, and Fe) form the principal geochemical associations of the ores. Twenty six ore minerals including sulfides, oxides, sulfosalts, sulfantimonides, alloys, intermetallic compounds, tellurides and selenides have been identified. The principal Zn- and Cu-minerals are sphalerite and chalcopyrite, respectively. Twelve Ag-bearing minerals were identified or inferred, of which sulfosalts and tellurides account for<24% of the Ag, Au-Ag-Hg alloy for <19% of the Ag, and galena for 3% of the Ag in the ore. Chalcopyrite, pyrite and sphalerite are inferred to contain 45, 11 and 55ppm Ag, respectively, corresponding to 23, 14 and 19% of the Ag in the ore. The average composition of Au-Ag-Hg alloy (in wt%) is 49.2% Ag, 38.7% Au, 11.0% Hg and 0.70% Fe. 'Invisible' Au in pyrite (0.72ppm Au) and arsenopyrite (30.2ppm Au) account for 6 and 1%, respectively of the Au in the ore; 93% occurs as Au-Ag-Hg alloy. From image analysis determined grain size data, minimum grinds for liberating sphalerite, chalcopyrite, pyrite, galena and freibergite are calculated as +208um, -175um, -95um, -48um and -60um, respectively. Similarly, the optimum grinds for liberating the above minerals are -52um, -52um, -26um, -9um and -5um, respectively. Predicted minimum liberations are 73% for sphalerite, and 69% for chalcopyrite. Two textural types of Au-Ag-Hg alloy are recognized: (1) inclusions, grain coatings on, interstitial-fillings and fracture-fillings in, pyrite; and (2) large (<5mm) anastomosing masses. The losses of Au to the tailings are due largely to extremely fine-grained Type 1 Au-Ag-Hg alloy entrapped in pyrite (64%), and Au in solid solution in pyrite and arsenopyrite (36%). The principal Ag losses to the tailings are largely due to Ag in solid solution in pyrite, and poor recovery of pyrargyrite. The environmentally hazardous elements As and Hg are largely rejected to the tailings, and backfilled underground. Chalcopyrite Stringer and Disseminated Pyrite + Chalcopyrite ore types represent tectonically flattened feeder pipe mineralization. Vein Quartz + Chalcopyrite ore type is evidence of limited sulfide mobilization during metamorphism. Diablastic texture, characterized by myrmekitic intergrowths of chalcopyrite, sphalerite and pyrrohotite was produced by a quartz-diorite intrusion of the large Lens 2 of north zone. This texture is not amenable to grinding, and may yield middling particles of chalcopyrite and sphalerite, which will be recovered in the Cu-concentrate.
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Sung, Yoo Hyun. "The Nature of Gold Mineralization in the Multistage Archean Sunrise Dam Gold Deposit, Eastern Yilgarn Craton, Western Australia." 2008. http://arrow.unisa.edu.au/vital/access/manager/Repository/unisa:36670.
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This thesis presents the results of a detailed study of the mineralogy and paragenesis of gold at the Sunrise Dam gold deposit. The Sunrise Dam mine is the largest gold deposit in the Archean Laverton Tectonic Zone of the Eastern Goldfields Province, Yilgarn Craton, Western Australia. A number of previous studies have established the geology, geochemistry and geochronology, but the nature of the gold mineralogy and distribution has remained poorly characterized. Mineralogical studies have established a paragenetic sequence consisting of five hydrothermal stages (D1, D2, D3, D4a and D4b) which are generally in accord with the major deformation events at Sunrise Dam gold deposit. The D4a stage was the dominant episode of Au deposition, followed, in importance by the D4b stage, which is characterized by more diverse ore mineralogy including base metal sulfides, sulfosalts, and telluride minerals. Based on EPMA results, native gold in D4a stage has higher purity, with a small range of Ag variations (fineness 923 ~ 977, average 945), than that of the D4b stage (fineness 596 ~ 983, average 899), in which fineness values decrease systematically in accord with mineral paragenesis, reflecting that gold deposition was from a progressively compositionally evolving hydrothermal fluid with respect to Au/Ag ratios. The occurrences of As-rich pyrites are restricted to steeply-dipping ore bodies, which are most likely structurally connected at various level by channel ways through which As-rich (D4a) hydrothermal fluid migrating upward. There is a systematic variation in composition of the tetrahedrite-group minerals ranging from Sb to As end-members with highly variable Zn:Fe ratios, which correlates with the later paragenetic stages (D3, D4a, and D4b) and mineral associations. The composition of the tetrahedrite-group minerals is useful as a petrogenetic indicator of the evolution of the hydrothermal mineralizing systems with time. A total of thirteen telluride mineral species, including two unnamed phases, were identified in the D4 veins. Among them nagyágite, the complex Pb-Sb-Au tellurosulfide is most abundant. The deposit is the second occurrence of this mineral in the Yilgarn Craton. Compositionally, nagyágite from Sunrise Dam conforms to ideal stoichiometry, with negligible As content and Au/(Au+Te) ratio of 0.325. The diverse mineralogy of the post-D4 veinlets relative to the host veins is attributed to small-scale reaction fronts established along zones of replacement. The presence of Au-Ag tellurides in D4 veins and the character of their breakdown products have implications for the gold recovery as well as for the genetic interpretation of the deposit. During the D4b stage, Au-richer telluride and Au-richer native gold mineralization formed earlier than Ag-(Au)-telluride and Ag-richer gold mineralization. Values of f(Te2) and f(S2) for the early telluride assemblages were determined at 300°C to be -10.7 to -7.8 (log fTe2) and 11.4 to -8.6( log fS2 ). The Au content of arsenian pyrite and arsenopyrite from four mineralizing stages (D1, D3, D4a and D4b) was measured using in-situ LA-ICP-MS. The average Au concentration is 44.5 ppm in pyrite (n = 224) with maximum value of 3,067 ppm, and 1,483 ppm in arsenopyrite (n = 35) with maximum value of 5,767 ppm, which are the highest concentrations reported for the Yilgarn Craton. The concentrations of invisible Au in arsenian pyrite at Sunrise Dam varies with mineralizing events, mineral paragenesis, and textural type. Gold is strongly enriched in D4a stage pyrite (average 80.8 ppm) and to a lesser extent in D4b pyrite (average 16.8 ppm). Pyrite from D1 (average 3.55 ppm) and D3 (average 2.96 ppm) show much lower levels of Au enrichment. The presence of metallic Au below the Au solubility limit in the Sunrise Dam pyrite is interpreted as evidence of an epigenetic origin for Au mineralization. Small-scale remobilization during dissolution-reprecipitation (D4a) and recrystallization (post-D4b) processes resulted in the Au enrichment and the upgrading of Au during successive hydrothermal events in the deposit. The speciation of Au at Sunrise Dam and the exceptional size of the deposit are the result of multiple fluid flow and multiple Au-precipitating mechanisms over a single plumbing system.
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Doucette, John. "A petrochemical study of the Mount Fubilan Intrusion and associated ore bodies, Papua New Guinea." Thesis, 2000. http://hdl.handle.net/1957/33496.
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The Mount Fubilan Intrusion is part of a geologically young hypabyssal stock in the Star Mountains of Papua New Guinea. This stock was mapped as the Ok Tedi Intrusive Complex and divided into four separate bodies: the Mount Fubilan, Sydney Intrusion, Kalgoorlie, and Ningi Intrusions. Hydrothermal fluids caused alteration of the Mount Fubilan, and parts of the other intrusions, to potassic and propylitic mineral assemblages and deposited gold and copper.
This investigation documents similarities and differences between the least-altered intrusive rocks of the complex and those that have undergone potassic metasomatism. The study involved detailed petrographic examination of more than two hundred thin-sections, major-oxide and trace element chemistry, and microprobe analyses of individual minerals. The magmas that crystallized to form the stock are shown to be intermediate in composition between andesite and latite. They were quartz-saturated, metaluminous, weakly iron-rich, and crystallized under oxidizing conditions. The principal mineral phases in the least-altered intrusive rocks are andesine, pyroxene, orthoclase, and quartz. The accessory mineral suite in least-altered rocks includes biotite, sphene, apatite, magnetite, and zircon.
Hornblende is present in a few samples Magmatic pyroxene is diopsidic in composition; hornblendes is cdenitic; and biotite is annitic. Potassic alteration has converted andesine to orthoclase, or mixtures of albite and orthoclase, ferro magnesian minerals to hydrothermal biotite, sphene to rutile, and magnetite to pyrite and chalcopyrite. Hydrothermal biotite is phlogopitic in composition. Gold and copper were concentrated in the zone of potassic alteration.
The mineralogical transformation of the intrusive rocks of the Mount Fubilan and associated intrusions was caused by the infiltration of hydrothermal fluids that deposited potassium, gold, and copper and that leached and removed virtually all other rock constituents. Leached components were transported away from the zone of potassic alteration and deposited in peripheral parts of the intrusive complex to form propylites, endoskarn, and massive replacement bodies or removed from the system entirely.
The Mount Fubilan intrusion was closely similar in chemistry and mineralogy to the other intrusions of the complex prior to alteration. Petrochemical differences between the Mount Fubilan Intrusion and the other intrusions were produced entirely by hydrothermal alteration.Graduation date: 2000
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"Geochemistry and mineralogy of supergene altered manganese ore below the Kalahari unconformity in the Kalahari manganese field, Northern Cape Province, South Africa." Thesis, 2009. http://hdl.handle.net/10210/1958.
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M.Sc.It is the focus of the study to qualitatively describe and then quantify the mineralogical and geochemical changes associated with the supergene alteration of carbonate-rich braunite lutite (Mamatwan-type ore) immediately below the Kalahari unconformity along the southeastern suboutcrop perimeter of the Hotazel Formation in the Kalahari deposit. It was also the objective of this study to determine the timing and duration of supergene alteration. Samples for polished thin sections were carefully selected from eight representative boreholes to be representative of all the lithostratigraphic zones and ore types. The thin sections were used to study mineralogy by means of reflected light microscopy and scanning electron microscopy. X-ray powder diffractometry on representative powder samples were used to study the mineralogy and geochemistry of the samples. Microprobe analyses were also performed on the representative samples. Finally the samples were submitted for 40Ar/39Ar geochronology. In this supergene enrichment zone carbonates are leached (associated with an increase in porosity) and Mn2+/Mn3+ -bearing minerals (kutnahorite, Mn-calcite an braunite) are altered to supergene Mn4+-bearing mineral phases (todorokite and manganomelane) and minor quartz. This process upgrades ore from 38 wt% Mn to ore with more than 40 wt% Mn. Element fluxes, enrichment and depletion of major and trace elements were quantified by mass balance calculations. Na2O, K2O, Sr, Ba, Zn and H2O were enriched, while Mn3O4, Fe2O3, CaO, MgO, P, B and CO2 were leached from the ore during supergene alteration. Results of this study suggest that the development of Post African I erosional surface may have taken place 45 Ma ago. The bottom of the weathering profile gives a well-defined peak at ca. 5 Ma that may possible coincide with the development of Post African II erosional surface. The major characteristics of the alteration process of the unaltered Mamatwan-type ore to supergene altered braunite lutite can be summarized as follow: • Leaching of Mn carbonates and Mn2+/Mn3+-oxides. • Formation of Mn4+-oxyhydroxides and quartz. • Decrease in relative density of the ore. • Increase in porosity of the ore. • Leaching of Mn3O4, Fe2O3, CaO, MgO, P, B, CO2. • Enrichment of Na2O, K2O, Sr, Ba, Zn, H2O. Chemical weathering processes along the Cenozoic Kalahari unconformity appear to have affected the manganiferous lithologies of the Hotazel Formation from 45 Ma onwards to 5 Ma. The weathering front processes very slowly through the Mn-rich braunite lutite (<10m in 40 Ma; <0.25m/Ma); producing a very uniform and microcrystalline supergene mineral assemblage with distinct characteristics.
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Preston, Paula Cristina Canastra Ramos. "Physical and chemical characterization of the manganese ore bed at the Mamatwan mine, Kalahari manganese field." Thesis, 2009. http://hdl.handle.net/10210/1967.
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M.Sc.The Mamatwan mine is situated at the most southern end of the world’s largest landbased resource of manganese, the Kalahari manganese field. The mine is operated by South African Manganese Corporation Limited (SAMANCOR) and is the largest open pit manganese mine in the world. The sedimentary manganese ore bed is interbedded with iron-formation of the Hotazel Formation of the Early Paleoproterozoic Voëlwater Subgroup of the Transvaal Supergroup. The open pit Mamatwan mine has a proven economic ore reserve of between 300 and 400Mt and produces 1.2Mt of manganese ore annually, of which 0.5Mt of ore is beneficiated and shipped through the harbour at Port Elizabeth. The remaining ore is railed to ferro-alloy plants at Meyerton and Newcastle. Carbonate-rich manganese lutite mined at the Mamatwan Mine is widely known as Mamatwan-type ore. It has a manganese content ranging from 30 – 38%. Only a small portion (15m of a total thickness of 49m) of the ore bed, containing an average of 38% Mn, is being mined and processed at present. The larger portion of the ore bed is not utilized. This study focuses on the physical and chemical characteristics of the ore bed in more detail in order to make suggestions on how to a) reduce waste by upgrading the upper parts of the lower manganese ore bed, or b) to improve the current recovery from the present economic zone. A second part of this study pays special attention to the lithostratigraphy of the lower manganese ore bed. The focus is on the paragenetic sequence and the diagenetic evolution of the braunite lutite that constitutes the manganese ore. The Mamatwan-type ore can be described as diagenetic to very low-grade metamorphic carbonate-bearing braunite manganolutite. Based on geochemical and mineralogical data, the lower manganese ore body was previously subdivided into eleven lithogically distinct zones. Based on detailed diamond drill core logging and with the aid of geochemical and physical data of two selected drill cores, an additional thirteen subzones were identified in this study. These new subzones were found to be consistent across the entire study area, located to the west and north of the present Mamatwan open pit. The paragenetic sequence recognised in the ore of the lower manganese ore bed can be subdivided into four stages, namely: (a) sedimentation, which is represented by fine lamination and the presence of fine-grained “dusty hematite”. (b) early diagenesis as represented by micritic carbonate matrix and possibly braunite, (c) late diagenesis or low-grade metamorphism are represented by coarse grained hausmannite, specularitic hematite, partridgeite and Mn-calcite, and supergene alteration that occurs immdediately below the contact of the ore bed to the unconformably overlying Tertiary Kalahari Formation. This supergene altered zone is marked by the presence of Mn4+ oxides such as cryptomelane, manjiroite, romanechite and pyrolusite, in addition to barite. The results obtained in this study permit definition of two sedimentary cycles within the manganese ore bed at the Mamatwan mine. Both cycles are defined by a carbonate-rich finely laminated zone at the base, overlain by a central manganese-rich economic zone, capped by manganese lutite that is enriched in carbonate ovoids. The two manganeserich zones are known as the M (lower) and X (upper) zone, and are characterized by the replacement of carbonate ovoids by hausmannite. The two Mn-rich zones are chemically and physically almost identical, with the M zone 7.5m thick and the X zone 5.5m thick. However, in the present mining configuration only the M zone is being mined. The most important result arising from the present study is the recommendation to restructure the future mining operation in order to mine not only the M zone, but also the X zone.
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Pickett, Jacob Wayne. "A geological and geochemical study of the Skidder basalt and Skidder trondhjemites : and the geology, ore petrology and geochemistry of the Skidder Prospect and its accompanying alteration zone, Buchans area, central Newfoundland /." 1988. http://collections.mun.ca/u?/theses,117885.
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(9673769), William E. Odom III. "Dating the Cenozoic incision history of the Tennessee and Shenandoah Rivers with cosmogenic nuclides and 40Ar/39Ar in manganese oxides." Thesis, 2020.
Find full textAbstract:
The post-orogenic history of the Appalachian Mountains, particularly the persistence of rough topography and the degree of river incision throughout the region, has been a longstanding focus of geomorphology studies. Numerous models have been developed to explain the evolution of this landscape, variously invoking episodic or continuous processes of uplift and erosion to drive the generation or reduction of topographic relief. Recently, late Cenozoic uplift has found favor as a mechanism for rejuvenating the topography of the southern and central Appalachians. This hypothesis has drawn on longitudinal river profiles, seismic tomography, and offshore sediment records as evidence of Neogene uplift.Radiometric dating of surficial deposits provides a means to directly test models of episodic and continuous landscape evolution, as well as the Neogene uplift hypothesis. The research described in this thesis dates surficial sediments (river terraces, alluvial fans, and a filled sinkhole) and supergene manganese oxides using 26Al/10Be burial dating and 40Ar/39Ar geochronology, respectively. Our cosmogenic 26Al/10Be dating provides detailed histories of aggradation and incision along the Shenandoah and Tennessee Rivers since the early Pliocene. 40Ar/39Ar dating of manganese oxides permits estimates of surface preservation and denudation in the Shenandoah Valley and nearby watersheds throughout the Cenozoic.
The results of our work in the Shenandoah Valley, Tennessee River basin, and intervening areas indicate that the Appalachians experienced no significant pulse of uplift during the Cenozoic. Long-term preservation of supergene manganese oxides dates as far back as the Eocene, demonstrating minimal denudation and discontinuous formation that lend evidence to episodic landscape evolution models. Cosmogenic26Al/10Be burial ages along the Shenandoah and Tennessee Rivers reveal Pliocene aggradation, with enhanced deposition in the Shenandoah Valley during the mid-Piacenzian Warm Period. Both rivers likely experienced incision during the Pleistocene, likely due to climatic fluctuations. These results demonstrate that while the Appalachian landscape has remained largely unchanged for tens of millions of years, rapid Pleistocene changes in base level recently triggered significant incision of major drainages.
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Smith, Albertus Johannes Basson. "The Paleo-environmental significance of the iron-formations and iron-rich mudstones of the Mesoarchean Witwatersrand-Mozaan Basin, South Africa." Thesis, 2009. http://hdl.handle.net/10210/2440.
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M.Sc.The Mesoarchean Witwatersrand and Pongola Supergroups of South Africa are the oldest, well preserved supracratonic successions worldwide. Various banded iron formation (BIF) and iron-rich mudstone units occur within the West Rand Group of the Witwatersrand Supergroup and the Mozaan Group of the Pongola Supergroup. A granular iron formation (GIF) occurs in a single unit in the Nconga Formation of the Mozaan Group. The Witwatersrand Supergroup and Mozaan Group have been lithostratigraphically correlated and are interpreted to have been part of the same sedimentary basin. The studied BIF units occur in two associations: shale-associated and diamictiteassociated BIF. The GIF seem to have been deposited in shallower environments with greater hydrodynamic activity. The iron-rich mudstone shows a similar stratigraphic setting to that of the shale-associated BIF. The lithostratigraphic setting of the Witwatersrand-Mozaan basin BIFs are similar to what is seen for Superior-type ironformations, with the mudstones and associated BIFs marking marine transgressions. Various mineralogical facies of BIF were identified, including oxide, carbonate and silicate facies BIF, as well as mixed facies between these end members. The GIF is a unique facies and shows abundant petrographic evidence for biological activity. The iron-rich mudstone has been subdivided into iron-silicate rich, magnetite-bearing, carbonate-bearing, magnetite-carbonate-bearing and garnet-bearing subtypes. BIF, GIF and iron-rich mudstone have been subjected to lower greenschist facies metamorphism with some occurences of localized contact metamorphism. The abundance of magnetite shows that oxidation played an important part in BIF deposition, whereas the occurrence of 12C-enriched iron-rich carbonates suggests post depositional reduction of the deposited oxidized iron-rich minerals by organic matter. Al-bearing minerals are rare in the BIFs xxi and abundant in the iron-rich mudstones. Apatite and rare earth element (REE)- phosphates occur throughout. The major element geochemistry shows an inverse proportionality for Fe and Si in all the studied samples. BIFs show slightly higher Fe- and lower Si- and Al-concentrations compared to iron-rich mudstones which show higher Si- and Al- and lower Feconcentrations. The studied BIFs show major element geochemical attributes intermediate to those of Superior- and Algoma-type iron-formations. Provenance studies on some of the iron-rich mudstones illustrate that they were sourced from a mixture of mafic and felsic sources. The rare earth element (REE) geochemistry suggests strong hydrothermal input into the units, and positive correlation with the Fe-concentrations suggests that the Fe was introduced by high temperature hydrothermal fluids. The majority of the REEs are hosted by apatite and the REE-phosphates monazite and xenotime. The REEs were reconcentrated into these phosphates during diagenesis. A comparison of the studied lithostratigraphically correlatable units between the Witwatersrand Supergroup and Mozaan Group makes it possible to construct a depositional model for basin-wide BIF deposition in the Witwatersrand-Mozaan basin. Shale-associated BIF was deposited during the peak of transgression when reduced Ferich hydrothermal bottom waters were introduced into shallow ocean water that was either oxygenated or filled with anoxygenic phototrophic bacteria. Diamictite-associated BIF, in contrast, was deposited during interglacial periods when the melting of glacial ice introduced sunlight, nutrients and oxygen to the reduced, hydrothermally influenced Ferich ocean water. GIF was probably deposited in shallow, above wave base waters cut off from clastic input, and then washed into deeper depositional environments. Iron-rich mudstone was deposited in a similar setting as the shale-associated BIF, but in environments that were not completely cut off from detrital influx. The study shows that it is impossible to construct a general depositional model for Precambrian BIFs, since the lithostratigraphic and depositional settings vary between different examples of BIF.
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Fitzhenry, Clifford. "The mineralogy, petrology and PGE geochemistry of the UG2 cyclic unit at Lebowa Platinum mine (ATOK), North-Eastern Bushveld complex." Thesis, 2008. http://hdl.handle.net/10413/1046.
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