Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography : leaves 281-295. / by William John Olszewski, Jr. / Ph.D.

The Clifton Migmatite crops out between the biotite grade Bucksport Formation (predominantly calcareous pelitic quartzite) on the west, the Lucerne Pluton (biotite granite) on the southeast, and the Parks Pond Pluton (mafic granite to quartz syenite) on the northeast. The Parks Pond crystallized at >1000°C. The leucosomes are I-type (metaluminous, hornblendebearing inclusions, primary titanite, allanite, hornblende, and apatite included in biotite or hornblende), or S-type (tourmaline and red-brown biotite). They are conformable with melanosome (Bucksport) layering, and vary in outcrop from 7-88% areally, and in composition from tonalite to alkali granite. Igneous textures in leucosomes argue against a solid-state origin, while biotite and plagioclase analyses indicate that leucosomes were not generated by in situ melting. Compositions of plagioclase (An-content 33-28 in melanosome, 38-15 in adjacent leucosome) and biotite (positive gradient of Ti02 in biotite of melanosome with approach to leucosome) demonstrate disequilibrium. It is argued that the Lucerne was not involved, based on chronology and mineralogy, and leucosomes are not injections of Parks Pond magma, because they lack clinopyroxene, orthopyroxene, and biotite from the Parks Pond. In the leucosomes, different maximum An-contents of plagioclase, four different orders of crystallization, and different compositions suggest that they are multiple melts. 4/5 of analyzed leucosomes are well described as Bucksport Formation minus restite. Conclusions: 1) The Parks Pond partially melted the Bucksport at depth. 2) Melts intruded by lit-par-lit injection to present exposures. 3) Caution should be exercised in applying I- and S-type criteria to melts of calcareous sediments. / Master of Science

Thesis submitted for the degree MAGISTER SCIENTIAE to the Faculty of Science, Department of Geology, University of the Witwatersrand, Johannesburg / The Koperberg Suite intrusion at Jubilee, Namaqualand varies in composition from anorthosite, through mica diorite to pyroxene leucodiorite and pyroxene diorite. Detailed mapping and petrological studies of these rocks indicate that they were sequentially emplaced into the Concordia Granite country rocks, and that each of the rock types represent discrete magmatic events. The sequence of intrusion is from more acidic to more basic. Whole-rock geochemical analyses indicate that these rocks represent cumulates involving variable proportions of plagioclase, orthopyroxene, mica, quartz, oxides and immiscible sulphides. These cumulate phases intruded into the Concordia Granite at the time of peak of metamorphism and deformation in the Okiep Copper District, i.e, about 1030Ma ago, At the time of intrusion, the country rocks were under going partial melting under high grade (granulite facies) metamorphic conditions. and granitic anatects were present in the crust. Hybridisation of basic magma and granitic melts occurred within the shear zones along which the basic magmas ascended. The En content of orthopyroxene in the Koperberg Suite exceeds the An content of plagioclase. This is atypical of basic intrusions and is a consequence of this mixing. Mixing calculations based on the initial 87Sr/86Srratio (Ru) of the Jubilee samples at 1030Ma, imply high levels of assimilation (as much as 80% assimilation in the case of anorthositic rocks) between a granitic component, similar in composition to the Nababeep Gneiss and a mantle-derived basic magma. Sulphide mineralisation was initiated by the assimilation process, which caused the separation of immiscible sulphides from the hybridised magma. Subsequent oxidation of the original sulphide assemblage produced bornite, chalcopyrite and Ti-poor magnetite. / Andrew Chakane 2019

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2016. / The Jacomynspan Ni-Cu sulphide mineralisation is hosted within a 100m thick steeply dipping tabular, differentiated, sill of mafic to ultramafic composition intruded into country gneissic rocks of the Namaqualand Metamorphic complex. This sill is predominantly composed of tremolite schist (metamorphosed pyroxenite) containing lenticular bodies of harzburgite. The harzburgite generally hosts net-textured mineralisation with up to 50% by volume of the rock. Massive sulphide veins and stringers are occasionally present within the harzburgite. The sulphide minerals are a typical magmatic assemblage of pyrrhotite, chalcopyrite and pentlandite. The sill covers an approximate strike length of about 5km but only a small portion covering 1km x 1km was selected for this study. Physical property studies carried out on the drill core (magnetic susceptibility and conductivity) indicate that the country gneissic rocks are not conductive and neither are they magnetically susceptible. However, the mineralized sill has elevated values of both magnetic susceptibility and relative conductivity compared to its host making it a suitable target for both magnetic and electromagnetic inversion. Drilling done so far on the study area has shown that the well-mineralised harzburgite (hosted within the poorly mineralised ultramafic sill) is not a continuous body but occurs in ‘pockets’. There is therefore need to use the available geophysical and geological datasets to derive a model of these well mineralised pods. This study is therefore intended to assess the feasibility of using electromagnetic (EM) methods together with other geophysical methods and geology in obtaining a model of the harzburgite pods hosted within the less conductive poorly mineralised ultramafic sill in order to guide further drilling. Geosoft’s VOXI Earth Modelling software was used to model the high resolution airborne magnetic data for this study. Cooper’s Mag2dc (www.wits.ac.za) and Stettler’s Magmodintrp software (personal communication, 2015) was also used during modelling of the magnetic data to compliment the modelling from VOXI. The mineralised ultramafic sill was clearly mapped in both the 3D model representation from Mag2dc modelling and VOXI’s 3D unconstrained smooth model inversion for the study area. Based on the physical properties studies carried out on the study area, EM data (both ground and downhole EM) were modelled using Maxwell software. The poorly mineralised tremolite schist was clearly modelled. In order to better constrain the targets, an assumption was made that at late decay times the currents would be focused in the centre of the large EM plate probably giving an indication of the most conductive part of the intrusion. Smaller ‘Resultant EM plates’ of dimensions, 300mx300m that coincide with the centre of the large EM plates (with a conductance above 100S) were constructed in iv Maxwell software and integrated with the DXF file of the Micromine geology model of the well mineralised harzburgite clearly mapping the well-mineralised harzburgite and showing its possible extensions. 2D inversion modelling was conducted on all audio-frequency magnetotelluric (AMT) data for this study area. The modelling results clearly mapped the mineralised intrusion.

M.Sc. / The Salt River deposit is a poly-metallic base metal deposit with a Zn-Cu-Pb metal content that occurs southwest of the town of Kakamas within the Northern Cape Province, South Africa. The Salt River deposit occurs within the Geelvloer Formation of the Bushmanland Subprovince of the Proterozoic Namaqua Metamorphic Province (NMP). This study constitutes the first detailed study of the host rock succession to the Salt River deposit, by investigating the lithostratigraphy, petrography geochemistry and geochronology. During the course of the study, various styles of wall-rock alteration were identified and investigated to determine their effect on the host rock succession. A further aim of this study was to classify the Salt River deposit and compare it to neighboring deposits occurring in the NMP. Geochronological studies were undertaken to define the age of mineralization. Detailed logging of exploration diamond drill core combined with petrographic investigation was used to define thirteen distinct lithotypes. The stratigraphy is dominated by felsic grey gneisses and mafic amphibolites, minor calc-silicate rocks, granitic augen gneisses, pegmatites and two lithologies that represent the metamorphosed equivalents of hydrothermally-altered host rock. Lithostratigraphic investigations yielded a rather uniform succession containing four distinct marker beds defined by their common occurrence and ease of correlation across various boreholes.

M.Sc. (Geology) / Please refer to full text to view abstract

Pražské metro jako prostor pro realizaci geologických exkurzí Abstract: The aim of this diploma thesis is to evaluate and explore the potential of the tiling materials used in the Prague metro and to create guidelines suitable for organizing geological excursions. Ysdfvwavweefawfbaljehbrrkvjasdhbflavjsdhbf alskdjfbalksjdfnaůksjdnaůkjsdfnaůksjsa Sdfasdfasdfasfavsdfvaskedjfnalksjdfnca weuifhmacskdjfmcapisdjfcaksdjnfcamůskdjfnmacsdkjfnmacůskjdfmnacůs kdjfmnaclskdjfnmacůskdjfnacf askdjfaůksjdf nasdkfjn askdjfn aůksjdnf aůskjdfn aůkjsdf akjsdn fakůjsd fnaůksjdfnaůksrjng adg

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Made available in DSpace on 2015-03-26T13:28:36Z (GMT). No. of bitstreams: 1 texto completo.pdf: 9035273 bytes, checksum: 309210e2946157c33b9a3a555deaca1b (MD5) Previous issue date: 2014-10-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Rock mass classification is a important procedure for the analysis of the mechanical behavior of a rock and its discontinuities, under the several applications on engineering projects such as, for example, underground mining. The present study has the aim of perform a geomechanical classification of the rock masses occurring under surface at Volta Grande mine, located in Nazareno, Minas Gerais State, Southeast Brazil, in order to evaluate the technical feasibility of development of an underground mine. Currently Volta Grande mine operates only an open pit mine for Tantalum in a pegmatitic body. Because its high waste-ore ratio both operational and commercial feasibility can become impracticable, as this ratio is expected to increase with open pit depth. All data necessary to classify the underground rock mass by using the two most widespread classification systems RMR and Q were collected to accomplish the proposed goals. Data were collected in 28 boreholes located on geological cross-sections, spread all over the area, previously selected in order to allow an adequate geological and geomechanical characterization of the study area for the initial underground proposed depth (150m). Sampling was done both for different rock and weathering grades types, in a quantity sufficient to perform all physical, point load, compressive strength, triaxial and wave velocity propagation tests. All tests were performed according to International Society for Rock Mechanics (ISRM) 2007 methods. Results were compared with similar rock- types results from the literature in order to evaluate its applicability. Results shows that both classification systems are in accordance with rock masses from superficial field observations. Nevertheless, it was observed that Q system was much more sensitive then RMR system, resulting in a higher number of rock mass classes. This higher sensitivity results mainly from RQD, Jn, Ja and Jr parameters, resulting in a very compartmentalized rock mass, considered not feasible for design purposes. Based on that assumption, RMR system is more recommended for using during feasibility studies as it encompasses several thin different class layers, resulting in a more applicable and handle system. It must be highlighted that the present study results are for feasibility studies only and cannot be applied for executive purposes, as much more quantity of data would be necessary. The final result points to a technical feasibility of underground mining, resulting in an increase of mine lifetime, reduction of waste-ore ratio, and provision of important initial mechanical information for excavation and support studies. / A classificação de maciços rochosos é um procedimento importante para a análise do comportamento mecânico das rochas e suas descontinuidades frente às solicitações que lhes serão impostas em decorrência de projetos de engenharia como, por exemplo, os de minas subterrâneas. O presente estudo teve por objetivo realizar a classificação geomecânica dos maciços rochosos da mina de Volta Grande, Nazareno-MG, Brasil, em profundidade, visando a avaliação da viabilidade técnica de implantação de lavra subterrânea. Atualmente, a mina opera a céu aberto a lavra de um corpo Pegmatítico intrusivo, em Anfibolito como rocha encaixante, para obtenção de Tântalo, que é um produto de alto valor agregado. A retirada do Pegmatito através de lavra a céu aberto pode se tornar inviável operacional e economicamente, pois o corpo do minério possui um mergulho de 20 graus para Sudeste, resultando em um aumento significativo da relação estéril-minério com o aumento da profundidade da cava. Para a realização do estudo foram coletados dados necessários à classificação dos maciços existentes em profundidade pelos dois métodos mais difundidos no mundo inteiro para este propósito - o sistema RMR e o sistema Q. A aplicação destes métodos demandou a caracterização geológico-geotécnica da área de estudo por meio da interpretação de testemunhos de sondagem obtidos em 28 furos, cuja distribuição espacial está relacionada à mRock mass classification applied to Volta Grande underground mine site, Nazareno, Minas Geraisalha de seções geológicas selecionadas previamente ao início do trabalho de campo, de maneira a permitir uma adequada caracterização da geologia e da geomecânica em profundidade para a área de estudo. A coleta de dados foi sistematizada fazendo-se o uso de uma planilha específica para obtenção dos parâmetros de classificação. Foram realizadas amostragens em testemunhos de sondagem, por litotipos e graus de alteração, em quantidade suficiente para a realização dos ensaios de caracterização física, de determinação da resistência à compressão puntiforme, compressão uniaxial, compressão triaxial e determinação da velocidade de propagação de ondas, todos realizados de acordo com as metodologias sugeridas pela International Society for Rock Mechanics ISRM. Os resultados destes ensaios foram comparados com os resultados de trabalhos semelhantes encontrados na literatura, a fim de se avaliar sua aplicabilidade. Os resultados da classificação geomecânica mostram que ambos os sistemas representam muito bem os maciços da mina de Volta Grande. No entanto, percebeu-se que o sistema Q é muito mais sensível em relação ao sistema RMR, principalmente nas mudanças de litologia, e essa sensibilidade aumentada para os parâmetros RQD, J n , J r e J a se traduz em resultados que, em alguns intervalos analisados, não se traduzem em ganho significativo em relação à condição geral observada para os maciços. Por isso, recomenda-se a utilização do sistema RMR em detrimento do sistema Q no intuito de diminuir a subdivisão do maciço em pequenas faixas com classes diferentes aumentando a segurança nas decisões uma vez que os resultados do sistema RMR permitiram a individualização, para a maioria dos intervalos, de uma menor subdivisão em faixas com pouca espessura, sendo considerado, por este motivo, o modelo geomecânico mais coerente para etapa de estudos de viabilidade técnica de uma lavra subterrânea. Ressalta- se que as classes de maciço foram definidas em etapa de projeto de viabilidade, não sendo, portanto, sugerida sua utilização na fase de projeto executivo, para o que se necessitaria de uma maior quantidade de dados. Do ponto de vista geotécnico o modelo final da classificação geomecânica dos maciços da mina de Volta Grande demonstra a viabilidade do início de uma lavra subterrânea, o que resultaria em aumento da vida útil da mina e diminuição da geração de estéril; além de fornecer informações iniciais para se inferir sobre tempo de auto-sustentação e tipos de contenção, se necessário, para um possível projeto de lavra subterrânea.

Abstract The metamorphosed Palaeoproterozoic Orivesi gold deposit in southern Finland is located within the Tampere Schist Belt, which belongs to the Svecofennian domain. The Orivesi mine, run by Outokumpu Mining Oy, was in production from 1994 to 2003, during which time a total of approximately 1.7 million tons of ore was extracted, with an Au content of 9.31 g/t, implying a total output 13.115 tons of gold in concentrate. The hydrothermal alteration halo can be divided successively into chlorite-dominant, sericite-dominant and quartz-dominant rocks from the outer zone inwards. The host rocks of the ore are quartz rocks with andalusite-rich quartz rocks. Topaz-bearing rocks also occur in the inner part of the alteration halo. In addition to Au, the elements Ag, Te, Bi, Sb, S, As, Se, Cu, Zn, Pb, Sn and Mo are enriched to varying degrees within the alteration halo. The main ore minerals include base metal sulphides, sulphosalts and tellurides. Pyrite is the most common sulphide. The sulphosalts are represented by tetrahedrite, bournonite, boulangerite and meneghinite. The most common gold, gold-silver and silver tellurides are calaverite, montbrayite, petzite, kostovite, sylvanite and hessite. Other known tellurides include tellurobismuthite, altaite, melonite, frohbergite, tsumoite, tetradymite and rucklidgeite. Gold occurs mostly in fine-grained native grains containing an average of 5% Ag. The native gold is usually of very small grain size, generally < 20 µm. Most of the gold grains in the deposit occur as intergrowths with tellurides. The adjacent hypabyssal intrusion is an obvious source of both hydrothermal fluids and metals. A comb quartz layering has been discovered in the transition zone between the intrusion and the alteration halo. The Orivesi deposit is thought to belong to the high-sulphidation epithermal type. Soon after its formation the deposit encountered deformation and metamorphism that amounted to lower amphibolite facies conditions. The subsequent retrograde metamorphism caused the reappearance of some hydrothermal minerals typical of high-sulphidation epithermal deposits.