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This paper presents the results of the spectrochemical analysis of a suite of rocks and rock minerals from the White Mountain magma series of New Hampshire and of some Finnish granites. The analysis elements are gallium, tin, lead, lithium, copper, and silver. / Thesis / Master of Science (MS)

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN. / Vita. / Bibliography: leaves 164-168. / by Teng-Fong Wong. / Ph.D.

Modal analysis on slabs, thin section petrography, microprobe analyses, and geological mapping have been performed on the Mount Airy granite and enclosing country rock. The pluton.is unzoned, simply intruded, and composed of a medium-grained, white granite, containing 33-41% plagioclase (An₁₀₋₂₀), 27-35% quartz, 20-28% alkali feldspar (Or₉₀), and 3-13% color index minerals, primarily biotite, muscovite, and epidote. A more granodiorite aplite phase intrudes the granite and is composed of An₉₋₃ plagioclase, Or₉₅ alkali feldspar, quartz, apatite, muscovite, biotite, and traces of epidote and zircon, and garnet. Aplite is a late segregation of granite and is associated with pegmatite. The enclosing country rock is amphibolite, pelitic schist, and pin-striped gneiss of the Alligator Back Formation. The pelites in contact with the granite on the southeast side have the assemblage garnet + biotite + staurolite consistent with the albite-epidote amphibolite facies metamorphism of the region. The granite has deformed the prior Ordovician foliation of the country rock and is itself cut by shears and folds close to the Brevard Zone. These are the result of Devonian-Mississippian movement on the Brevard. Some of the muscovite is primary in the granite, and epidote is not. Most of the muscovite, sphene, and low-An plagioclase are subsolidus. Alteration of biotite and plagioclase show an early, water-rich fluid evolving into a more CO₂-rich fluid as the rocks cooled. An injection temperature of 700-750°C and pressure of at least 5.5-7 Kbar is consistent with the mineral assemblages seen in the granite, xenoliths, and contact country rocks. The notable lack of hydrothermal activity at the granite margins is attributed to low H₂O content of the original magma and hydration reactions within the granite below the solidus. / Master of Science

In Hancock County, Maine, a small mineralized fine-grained granite lies at the southeast portion of the felsic Lucerne pluton, near the contact with the Blue Hill pluton. The Cambro-Ordovician, chlorite-rich Ellsworth schist occurs to the north and south of the younger fine-grained granite and is the host to many sulfide deposits within the region. Within the study area the fine-grained granite and the Ellsworth schist have been contact metamorphosed by the Devonian age Lucerne. The fine-grained granite is a quartz-rich, leucocratic, two-mica, two-feldspar granitoid. It is marked by the presence of 1) sulfides (pyrrhotite, pyrite, loellingite, arsenopyrite, chalcopyrite, and sphalerite) 2) volatile-rich phases such as muscovite, tourmaline, apatite, and chlorite, and 3) high-temperature anhydrous phases such as andalusite and fibrolite. Feldspars have been partially altered to muscovite, and biotite has partially altered to chlorite. Sulfides and tourmaline appear to have formed late in the crystallization sequence. Prior to the intrusion of the Lucerne the fine-grained granite probably cooled to a maximum temperature of about 600°C, and crystallized to form feldspar, biotite, quartz, and muscovite. Andalusite and sillimanite probably formed when the Lucerne intruded; at about 650-725°C and about 1-2 kilobars. Quartz, muscovite, tourmaline and sulfides probably formed during subsequent cooling. Feldspar composition indicate reequilibration with a fluid at about 400°C. Dehydration reactions within the Ellsworth schist probably resulted in the release of metal bearing fluids from the Ellsworth schist and redeposition into the adjacent fine-grained granite. / M.S.

This thesis focuses on mineralogy, geochemistry, and origin of eight pegmatites and two spatially associated granites of Late Archean and Paleoproterozoic ages located in Marquette and Dickinson Counties, Michigan. Biotite geochemistry reveals that both granites and all pegmatites are peraluminous and have an orogenic signature. However, bulk composition reveals the Humboldt granite is a peraluminous A-type granite and the Bell Creek granite is a peraluminous mix between I-, S-, and A-type granites. The Republic Mine pegmatite appears to be geochemically similar to the Bell Creek granite and Grizzly pegmatite. The Crockley pegmatite is genetically related to the Humboldt granite. The Groveland Mine, Sturgeon River, and Hwy69 pegmatites appear to be a product of the Peavy Pond Complex being contaminated with the Marquette Range Super Group. Contamination and anatexis have made classification of the granites and pegmatites problematic. The Grizzly should be classified as a primitive LCT-type even though this pegmatite lacks characteristic enrichment associated with LCT pegmatites. Mineralogical geochemistry reveals that the Republic Mine is relatively more primitive than other pegmatites and should be classified as a primitive Mixed-type pegmatite. Groveland Mine has mineralogy and geochemistry not normally associated with NYF-type pegmatites and should be classified as Mixed. The Crockley pegmatite should be classified as NYF-type with a primitive LCT overprint. Dolfin, Hwy69, Sturgeon River, and Black River pegmatites should be classified as Rare Element, REE, NYF-type, although the Black River has slight tantalum enrichment expressed in columbite group minerals.

En l’espace de cinquante ans l’exploitation minière d’uranium en France a généré 163 millions de tonnes de stériles miniers à l’échelle du territoire. Ces stériles, stockés sous forme de verses sont sujets à une altération météorique accrue par rapport à un massif granitique naturel. Dans le cadre du plan de gestion des matériaux et déchets radioactifs (PNGMDR) les stériles miniers sont l’objet d’une attention particulière visant à caractériser leur impact environnemental. Cette étude précise la géostructure des verses à stériles avec le développement d’un modèle structural typique pour aboutir à une caractérisation géochimique et minéralogique de ces stériles et permettre d’évaluer la stabilité de l’uranium. De cette étude, il apparaît très clairement que l’uranium est principalement associé aux phosphates, dans des phases héritées telles que les monazites ou sous formes d’uranyle-phosphates secondaires. Lorsque l’U est associé à des oxyhydroxydes de fer amorphes, le phosphore est également présent. Cette étude illustre le rôle majeur que peuvent jouer les oxyhydroxydes de fer et le phosphore dans le piégeage de l’uranium. Ces phases constituent un piège efficace et relativement stable, permettant de limiter les concentrations en uranium en solution à condition que les conditions environnementales restent stables. Quand bien même des changements d’équilibre auraient lieu, la présence de smectite dans les échantillons de la verse à stériles présente une barrière supplémentaire à la diffusion de l’uranium dans l’environnement. / In a time span of 50 years uranium mining in France generated 163 Mt of waste rocks. These form waste rocks piles which are subjected to enhanced weathering compared to natural granitic outcrops. Therefore, as part of the French radioactive waste and material management plan (PNGMDR), waste rocks are studied in order to assess their potential environmental impact. This study specifically focuses on the internal structure of waste rock piles complemented by geochemistry and mineralogical data, in order to develop a model that assesses the waste rock pile’s weathering state and uranium’s stability. Results show uranium (U) is mainly associated to phosphates, either in primary accessory minerals, such as monazites, or crystallized in secondary uranyl-phosphates. When U is associated to amorphous iron oxyhydroxides, phosphorous is also associated. The importance of iron oxyhydroxides and phosphorous in uranium trapping is clearly demonstrated. Both iron oxyhydroxides as well as uranyl-phosphates form efficient and stable U traps, limiting U dissolution as long as pH, redox and temperature parameters remain stable. In case of variable conditions, smectite identified in the waste rock pile might also play a role in preventing further uranium diffusion.

Basé sur une recherche menée dans le secteur minier brésilien, ce texte défend la nécessité d'une meilleure intégration des propositions faites dans les systèmes de travail afin de contribuer à la prévention de la santé, de la sécurité et du bien-être des employés.Pour faire face à des effets désastreux sur la santé dans de nombreuses situations, un moyen d'action est de réduire ces effets par des prescriptions normatives. Cependant, une telle approche s’avère inefficace en raison de ses difficultés à prendre en compte les activités du travail et les problèmes de production. La prévention peut alors échouer, en raison de son désaccord avec les stratégies industrielles.La recherche examine la mise en oeuvre d’une norme, puis de solutions techniques autour du principe d’humidification, dont le but a été d'empêcher l'émergence et la multiplication des pneumoconioses dans le secteur de l'exploitation minière au Brésil. La plupart des entreprises ont abandonné l’humidification. Cependant, la recherche a montré que certaines entreprises adoptent avec succès les techniques d'humidification.Dans ces entreprises, un processus d’« appropriation systémique » apparaît comme étant au coeur de la réussite. L'idée centrale est que l'introduction d'une nouveauté génère un processus au cours duquel un individu produit des ressources pour l'effectuation de sa propre activité (« appropriation individuelle »), mais il peut y avoir également un processus de propagation au sein d'un réseau d'acteurs interdépendants : les autres acteurs du réseau doivent prendre en compte ce changement au niveau de leurs propres activités. Sur base de cette analyse, le texte fera des propositions pour accompagner et soutenir un tel processus de propagation dans les milieux de travail. Car ce dernier est efficient pour tenir ensemble objectifs de santé, de sécurité, et logiques industrielles. / Based on a research carried out in the Brazilian mining sector, the text argues for the necessity of a better integration in work systems of the proposals made in order to contribute to prevent health, safety and welfare for employees.Facing with deleterious effects on health in numerous situations, one tempting way of action is to reduce these effects through normative prescriptions. However, such an approach can be ineffective due to its difficulties to take into account the work activities and the issues of production. Prevention then can fail, due to its disconnection with the industrial strategies.The article examines the introduction of a technical solution ("humidification"), whose the purpose was to prevent the emergence and multiplication of pneumoconioses in the mining sector in Brazil. Most of the companies in the field gave up on humidification. However, the research showed that certain companies adopt successfully the humidification techniques.In these companies, a process named “systemic appropriation” appears as being at the core of the success. The central idea is that the introduction of a novelty generates a process during which an individual produces the resources for the effectuation of its own activity (“individual appropriation”), but there is the need of a propagation process within a network of interdependent actors: the other actors of the network must take this change into account at the level of their own activities. Based on this analysis, the text will make proposals to accompany and support such an efficient propagation process within work settings. / Baseado numa pesquisa feita no setor de mineração brasileiro, o texto argumenta sobre a necessidade de uma melhor integração no sistema de trabalho cuja proposta visa contribuir com a prevenção de saúde, segurança e bem-estar para os empregados.Em face de inúmeras situações com efeitos deletérios à saúde, um caminhos de ação tentador é reduzir esses efeitos através de prescrições normativas. Entretanto, tal abordagem pode ser ineficiente devido às dificuldades de se considerar as atividades de trabalho e as questões de produção. A prevenção pode, então, falhar, devido à sua desconexão com a estratégia industrial.O artigo avalia a introdução de uma solução técnica (umidificação), cuja proposta era prevenir a emergência e multiplicação de pneumoconioses no setor de mineração no Brasil. A maioria das empresas neste campo, desistiram da umidificação. No entanto, a pesquisa mostrou que algumas empresas adotaram com sucesso as técnicas de umidificação.Nestas empresas, o processo chamado de apropriação sistêmica apareceu como sendo o núcleo do sucesso. A ideia central é que a introdução de uma novidade gera um processo durante o qual um indivíduo produz recursos para a efetuação de sua própria atividade (apropriação individual), mas existe a necessidade de um processo de propagação dentro de uma rede de atores interdependentes: outros atores da rede de trabalho devem considerar essas modificações no nível de suas próprias atividades. Baseado nessas análises, o texto fará propostas para acompanhar e dar suporte a tais processos de propagação dentro da configuração de trabalho.

>Magister Scientiae - MSc / The Sea Point contact, Cape Town, South Africa, exposes the contact between the Neoproterozoic Malmesbury Group metasedimentary rocks of the Pan-African Saldania belt and the intrusive S-type Peninsula Granite of the Neoproterozoic-Paleozoic Cape Granite Suite (CGS). The exposure outcrops over an area of approximately 170 m × 60 m with the northern end of the exposure being characterized by the country rock–microgranite intrusive contact. Heading further south, the outcrop transitions to the main contact zone, which is a predominantly gradational zone marked by sheets of compositionally variable granitic injections (collectively referred to as hybrid granite phases) concordant to the country rock structure, before reaching the main pluton area comprising the voluminous coarse-grained porphyritic granite. Using a combined study incorporating field, structural, geochemical, isotopic and U-Pb geochronological data, the intrusive contact is investigated to determine the construction history of the pluton and delineate possible emplacement mechanisms. The granitic phases, which vary from fine-grained leucocratic, medium-grained porphyritic to coarse-grained porphyritic, are peraluminous, magnesian to ferroan, and alkali-calcic. Based on the linear trends between the whole-rock major and trace element content of the granites vs. maficity (molar Fe + Mg), their initial Sr ratios and εNd(t) values, the granites of the study area are consistent with the currently proposed petrogenetic model for the CGS (e.g. Stevens et al., 2007; Villaros et al., 2009a; Harris & Vogeli, 2010); i.e., they are crustally derived and their chemical variability is controlled primarily by peritectic assemblage entrainment. The fractional crystallization of K-feldspar is identified as the primary mechanism for the local geochemical variability of the granites. The fractionation of K-feldspar as a mechanism of variability was evaluated using binary log-log diagrams of Ba, Sr and Eu and is interpreted to have taken place at levels close to the emplacement site after source entrainment processes. Although there is outcrop evidence, particularly in the main contact zone, to suggest that local assimilation and filter pressing took place, this was not reflected by the whole-rock and isotope geochemistry of the granites. This suggests that these processes are very localized and will need further rigorous testing to ascertain the extent to which they caused variability. Outcrop evidence for assimilation includes gradational country rock-granite contacts and the ductile behaviour of the country rock, whereas the occurrence of K-feldspar megacrysts embedded in the country rock at the main contact zone suggests melt accumulation and escape consistent with the filter pressing mechanism. In the case of the latter, the melt fraction of the granite was easily mobilized and driven out compared to the crystal fraction (K-feldspars) during the emplacement of the granites. Field relationships and the structural interpretation of the Malmesbury Group country rocks and the granites reveal that: (1) the various granites are late syn-tectonic and (2) were emplaced as incrementally assembled, repeated pulses of inclined granitic sheets more or less normal (i.e. at high angles) to the regional NE-SW shortening (D1) of the Malmesbury forearc during the Saldanian orogeny. Given the lack of a controlling shear zone in facilitating granite emplacement in the study area, the pre-existing planar anisotropies (bedding planes and foliations) in the country rock provided preferential pathways for magma emplacement and propagation during deformation. This implies that the tensile strength normal and parallel to the bedding and foliation anisotropy of the country rock was larger than the regional differential stress (σ1 – σ3, with σ1 ≥ σ2 ≥ σ3), allowing for magma emplacement relative to shortening. Sheet propagation is interpreted to have occurred through the balance of the following conditions: (1) density contrasts between host rocks and magmas, (2) the pressure differential along the subvertical fractures/sheets, and (3) the melt pressure equalling the lithostatic pressure to keep the magma pathways open and being sufficiently high such that it exceeds the sum of σ1 and the tensile strength of the rock parallel to σ1. The crystallization ages of the dated granite samples are identical within error and vary between 538.7 ± 3.6 Ma and 542.7 ± 2.9 Ma. They, therefore, cannot prove which granite phase intruded first and which one proceeded and so forth. Field relationships, however, suggests that the microgranites were first to intrude given their fine-grained nature and the localized chilled contacts they show with the country rock. The various coarser-grained and porphyritic phases were next to intrude, with their coarse grain-sizes and lack of chilled margins with the country rock suggesting that the time interval between their successive emplacements was not too long; this prevented the country rock from completely cooling down between each magma batch. Magma stoping and the ductile flow of the host material (owing to highly viscous magma flow) to accommodate granite emplacement are interpreted to be secondary emplacement processes.