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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Metamorphic refinement of quartz under influence of fluids during exhumation with reference to the metamorphic/metasomatic evolution observed in amphibolites : a detailed field, microtectonic and geochemical study from the Bamble sector, South Norway

Sørensen, Bjørn Eske January 2007 (has links)
<p>Outline of the thesis</p><p>This thesis is comprises three papers that are intended for journal publication. The version provided in the thesis is a bit longer than they will be at final publication. However it was the desire to include some additional documentation that may be omitted in the final versions. Each paper in the manuscript is written as an independent paper. Because all the papers are strongly tied together there is significant repetition partly because the documentation and interpretation of the results in on paper depends on the results documented in another paper. The essence of the three papers are summarised below:</p><p>Paper 1:</p><p>Sørensen, B.E. and Larsen R.B. 2007. “Fluid induced multistage recrystallisation microstructures in Quartzites and Quartz veins from the Bamble shear zone complex”</p><p>Paper 1 deduces basic principles of infiltration, physiochemical alteration processes and deformation mechanisms in quartzites and in quartz veins from the Froland area, the Bamble sector. SEM-CL is used to define generations of recrystallised quartz. A progressive quartz purification process ending with high purity quartz through recrystallisation is documented through LA-ICP-MS. The study demonstrates how fluids provokes recrystallisation and trace element mobilisation from the quartz lattice and at fluid-absent conditions, quartz is resistant to retrograde recrystallisation hence preserving its early high grade metamorphic trace element signature. Evidence of retrograde fluid flow is preserved in fluid channel textures intersecting quartz and documented by SEM-CL images as well as changes in the trace element distribution. Quartz recrystallisation is associated with metasomatic processes in the quartzites such as for example the replacement of ilmenite by rutile and replacement of biotite by muscovite. The strong focus of fluid flow along narrow pathways intersecting the quartzites generates mm-scale differences in the rheological properties of the quartz grains with increased ductility and recovery in recrystallised grains. Therefore, the study demonstrates a strong coupling between strain softening, fluid flow and mass transfer in shearzones in quartz rich rocks.</p><p>Paper 2:</p><p>Sørensen, B.E. and Larsen R.B. 2007. “The fluid evolution of the Froland area in the Bamble sector from peak P-T through cooling and uplift: implications for retrograde mineral paragenesis and PT evolution of the Bamble sector”</p><p>Paper 2 comprises a detailed characterisation of the fluid evolution during cooling and uplift through fluid inclusion studies compared with thermodynamic modelling of calc-silicate volatile dependant mineral equilibria. Fluids are documented to be brines throughout the cooling and uplift path. The paper also includes a detailed discussion of the chemical properties of the aggressive brines and their implications for mineral equilibria during cooling and exhumation. The study also document which fluids that were in equilibrium with quartz recrystallisation and purification. The study focussed on fluids that could be related to the quartz SEM-CL textures documented in Paper 1. Had the main purpose of this thesis been to understand calc-silicate equilibria in the Bamble sector fluid inclusions in the calc-silicates would have been in the focus.</p><p>Paper 3:</p><p>Sørensen, B.E, Larsen R.B. and Austrheim, H. 2007. “Metasomatic evolution of the Froland amphibolites during cooling and uplift – textural observations and geochemical evolution of hydrous minerals”</p><p>Paper 3 comprises a detailed study of alteration processes in amphibolites. The study focuses on the chemistry of amphiboles as a function P, T and the composition of the co-existing fluids. Amphibole and biotite undergo a co-genetic evolution both becoming more Mg-rich during cooling and exhumation. The chemical changes in biotite and amphibole reflects the interaction with the brines present throughout cooling and uplift. A relationship between element depletion in amphibolites and formation of Fe-Cu sulphides is observed.</p><p>As earlier stated the papers are strongly tied together. In conjunction with each other they deduce the metamorphic and metasomatic evolution of the area and put the observed quartz recrystallisation and purification into a physiochemical framework. The locality numbering varies between the papers because samples from different localities are included in each paper, accordingly a locality termed”1” in one of the papers may have a different number in the next paper. This was done because the papers are supposed to be independent research papers and the numbering logically relate to the context of the single papers and not the thesis as a whole.</p>
2

Metamorphic refinement of quartz under influence of fluids during exhumation with reference to the metamorphic/metasomatic evolution observed in amphibolites : a detailed field, microtectonic and geochemical study from the Bamble sector, South Norway

Sørensen, Bjørn Eske January 2007 (has links)
Outline of the thesis This thesis is comprises three papers that are intended for journal publication. The version provided in the thesis is a bit longer than they will be at final publication. However it was the desire to include some additional documentation that may be omitted in the final versions. Each paper in the manuscript is written as an independent paper. Because all the papers are strongly tied together there is significant repetition partly because the documentation and interpretation of the results in on paper depends on the results documented in another paper. The essence of the three papers are summarised below: Paper 1: Sørensen, B.E. and Larsen R.B. 2007. “Fluid induced multistage recrystallisation microstructures in Quartzites and Quartz veins from the Bamble shear zone complex” Paper 1 deduces basic principles of infiltration, physiochemical alteration processes and deformation mechanisms in quartzites and in quartz veins from the Froland area, the Bamble sector. SEM-CL is used to define generations of recrystallised quartz. A progressive quartz purification process ending with high purity quartz through recrystallisation is documented through LA-ICP-MS. The study demonstrates how fluids provokes recrystallisation and trace element mobilisation from the quartz lattice and at fluid-absent conditions, quartz is resistant to retrograde recrystallisation hence preserving its early high grade metamorphic trace element signature. Evidence of retrograde fluid flow is preserved in fluid channel textures intersecting quartz and documented by SEM-CL images as well as changes in the trace element distribution. Quartz recrystallisation is associated with metasomatic processes in the quartzites such as for example the replacement of ilmenite by rutile and replacement of biotite by muscovite. The strong focus of fluid flow along narrow pathways intersecting the quartzites generates mm-scale differences in the rheological properties of the quartz grains with increased ductility and recovery in recrystallised grains. Therefore, the study demonstrates a strong coupling between strain softening, fluid flow and mass transfer in shearzones in quartz rich rocks. Paper 2: Sørensen, B.E. and Larsen R.B. 2007. “The fluid evolution of the Froland area in the Bamble sector from peak P-T through cooling and uplift: implications for retrograde mineral paragenesis and PT evolution of the Bamble sector” Paper 2 comprises a detailed characterisation of the fluid evolution during cooling and uplift through fluid inclusion studies compared with thermodynamic modelling of calc-silicate volatile dependant mineral equilibria. Fluids are documented to be brines throughout the cooling and uplift path. The paper also includes a detailed discussion of the chemical properties of the aggressive brines and their implications for mineral equilibria during cooling and exhumation. The study also document which fluids that were in equilibrium with quartz recrystallisation and purification. The study focussed on fluids that could be related to the quartz SEM-CL textures documented in Paper 1. Had the main purpose of this thesis been to understand calc-silicate equilibria in the Bamble sector fluid inclusions in the calc-silicates would have been in the focus. Paper 3: Sørensen, B.E, Larsen R.B. and Austrheim, H. 2007. “Metasomatic evolution of the Froland amphibolites during cooling and uplift – textural observations and geochemical evolution of hydrous minerals” Paper 3 comprises a detailed study of alteration processes in amphibolites. The study focuses on the chemistry of amphiboles as a function P, T and the composition of the co-existing fluids. Amphibole and biotite undergo a co-genetic evolution both becoming more Mg-rich during cooling and exhumation. The chemical changes in biotite and amphibole reflects the interaction with the brines present throughout cooling and uplift. A relationship between element depletion in amphibolites and formation of Fe-Cu sulphides is observed. As earlier stated the papers are strongly tied together. In conjunction with each other they deduce the metamorphic and metasomatic evolution of the area and put the observed quartz recrystallisation and purification into a physiochemical framework. The locality numbering varies between the papers because samples from different localities are included in each paper, accordingly a locality termed”1” in one of the papers may have a different number in the next paper. This was done because the papers are supposed to be independent research papers and the numbering logically relate to the context of the single papers and not the thesis as a whole.
3

Automated Extraction and Retrieval of Metadata by Data Mining : a Case Study of Mining Engine for National Land Survey Sweden

Dong, Zheng January 2010 (has links)
<p>Metadata is the important information describing geographical data resources and their key elements. It is used to guarantee the availability and accessibility of the data. ISO 19115 is a metadata standard for geographical information, making the geographical metadata shareable, retrievable, and understandable at the global level. In order to cope with the massive, high-dimensional and high-diversity nature of geographical data, data mining is an applicable method to discover the metadata.</p><p>This thesis develops and evaluates an automated mining method for extracting metadata from the data environment on the Local Area Network at the National Land Survey of Sweden (NLS). These metadata are prepared and provided across Europe according to the metadata implementing rules for the Infrastructure for Spatial Information in Europe (INSPIRE). The metadata elements are defined according to the numerical formats of four different data entities: document data, time-series data, webpage data, and spatial data. For evaluating the method for further improvement, a few attributes and corresponding metadata of geographical data files are extracted automatically as metadata record in testing, and arranged in database. Based on the extracted metadata schema, a retrieving functionality is used to find the file containing the keyword of metadata user input. In general, the average success rate of metadata extraction and retrieval is 90.0%.</p><p>The mining engine is developed in C# programming language on top of the database using SQL Server 2005. Lucene.net is also integrated with Visual Studio 2005 to build an indexing framework for extracting and accessing metadata in database.</p>
4

Kemisk stabilisering av gruvavfall från Ljusnarsbergsfältet med mesakalk och avloppsslam : Chemical stabilization of mine waste with sewage sludge and calcium carbonate residues

Höckert, Linda January 2007 (has links)
<p>Chemical stabilization of mine waste from Ljusnarsbergsfältet with sewage sludge and calcium carbonate residues</p><p>Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved</p><p>oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as complexing agents for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed.</p><p>The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for</p><p>complexation a pH-stat batch test was used. Drainage water samples, from the columns,</p><p>were regularly taken during the experiment. These samples were analyzed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test was only analyzed on a few occasions and only for metal content and change in DOC concentration.</p><p>The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilization with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilize metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching.</p>
5

Automated Extraction and Retrieval of Metadata by Data Mining : a Case Study of Mining Engine for National Land Survey Sweden

Dong, Zheng January 2010 (has links)
Metadata is the important information describing geographical data resources and their key elements. It is used to guarantee the availability and accessibility of the data. ISO 19115 is a metadata standard for geographical information, making the geographical metadata shareable, retrievable, and understandable at the global level. In order to cope with the massive, high-dimensional and high-diversity nature of geographical data, data mining is an applicable method to discover the metadata. This thesis develops and evaluates an automated mining method for extracting metadata from the data environment on the Local Area Network at the National Land Survey of Sweden (NLS). These metadata are prepared and provided across Europe according to the metadata implementing rules for the Infrastructure for Spatial Information in Europe (INSPIRE). The metadata elements are defined according to the numerical formats of four different data entities: document data, time-series data, webpage data, and spatial data. For evaluating the method for further improvement, a few attributes and corresponding metadata of geographical data files are extracted automatically as metadata record in testing, and arranged in database. Based on the extracted metadata schema, a retrieving functionality is used to find the file containing the keyword of metadata user input. In general, the average success rate of metadata extraction and retrieval is 90.0%. The mining engine is developed in C# programming language on top of the database using SQL Server 2005. Lucene.net is also integrated with Visual Studio 2005 to build an indexing framework for extracting and accessing metadata in database.
6

Kemisk stabilisering av gruvavfall från Ljusnarsbergsfältet med mesakalk och avloppsslam : Chemical stabilization of mine waste with sewage sludge and calcium carbonate residues

Höckert, Linda January 2007 (has links)
Chemical stabilization of mine waste from Ljusnarsbergsfältet with sewage sludge and calcium carbonate residues Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as complexing agents for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed. The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for complexation a pH-stat batch test was used. Drainage water samples, from the columns, were regularly taken during the experiment. These samples were analyzed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test was only analyzed on a few occasions and only for metal content and change in DOC concentration. The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilization with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilize metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching.
7

Predicting surfacing internal erosion in moraine core dams

Rönnqvist, Hans January 2010 (has links)
<p>Dams that comprise broadly and widely graded glacial materials, such as moraines, have been found to be susceptible to internal erosion, perhaps more than dams of other soil types. Internal erosion washes out fine-grained particles from the filling material; the erosion occurs within the material itself or at an interface to another dam zone, depending on the mode of initiation. Whether or not internal erosion proceeds depend on the adequacy of the filter material. If internal erosion is allowed, it may manifest itself as sinkholes on the crest, increased leakage and muddy seepage once it surfaces, which here is called surfacing internal erosion (i.e. internal erosion in the excessive erosion or continuation phase). In spite of significant developments since the 1980s in the field of internal erosion assessment, the validity of methods developed by others on broadly graded materials are still less clear because most available criteria are based on tests of narrowly graded granular soils. This thesis specifically addresses dams that are composed of broadly graded glacial soils and investigates typical indicators, signs and behaviors of internal erosion prone dams. Based on a review of 90+ existing moraine core dams, which are located mainly in Scandinavia as well as North America and Australia/New Zealand, this thesis will show that not only the filter’s coarseness needs to be reviewed when assessing the potential for internal erosion to surface (i.e., erosion in the excessive or continuing phase); in addition, the grading stability of the filter and the core material as well as non-homogeneities that are caused by filter segregation need to be studied. Cross-referencing between these aspects improves the assessment of potential for internal erosion in dams of broadly graded soils and furthermore it provides aid-to-judgment.</p> / QC 20100715
8

Wellbore stability analysis based on a new true-triaxial failure criterion

Al-Ajmi, Adel January 2006 (has links)
A main aspect of wellbore stability analysis is the selection of an appropriate rock failure criterion. The most commonly used criterion for brittle failure of rocks is the Mohr-Coulomb criterion. This criterion involves only the maximum and minimum principal stresses, s1 and s3, and therefore assumes that the intermediate stress s2 has no influence on rock strength. When the Mohr-Coulomb criterion had been developed, it was justified by experimental evidence from conventional triaxial tests (s1&gt;s2=s3). Based on triaxial failure mechanics, the Mohr-Coulomb criterion has been extensively used to represent rock failure under the polyaxial stress state (s1&gt;s2&gt;s3). In contrast to the predictions of Mohr-Coulomb criterion, much evidence has been accumulating to suggest that s2 does indeed have a strengthening effect. In this research, I have shown that Mohr-Coulomb failure criterion only represents the triaxial stress state (s2=s3 or s2=s1), which is a special case that will only occasionally be encountered in situ. Accordingly, I then developed a new true-triaxial failure criterion called the Mogi-Coulomb criterion. This failure criterion is a linear failure envelope in the Mogi domain (toct-sm,2 space) which can be directly related to the Coulomb strength parameters, cohesion and friction angle. This linear failure criterion has been justified by experimental evidence from triaxial tests as well as polyaxial tests. It is a natural extension of the classical Coulomb criterion into three dimensions. As the Mohr-Coulomb criterion only represents rock failure under triaxial stress states, it is expected to be too conservative in predicting wellbore instability. To overcome this problem, I have developed a new 3D analytical model to estimate the mud pressure required to avoid shear failure at the wall of vertical, horizontal and deviated boreholes. This has been achieved by using linear elasticity theory to calculate the stresses, and the fully-polyaxial Mogi-Coulomb criterion to predict failure. The solution is achieved in closed-form for vertical wellbores, for all stress regimes. For deviated or horizontal wellbores, Mathcad programs have been written to evaluate the solution. These solutions have been applied to several field cases available in the literature, and the new model in each case seems to be consistent with the field experience. / QC 20100629
9

Numerical analyses of stability of a gradually raised tailings dam

Zardari, Muhammad Auchar January 2013 (has links)
Numerical analyses are presented in this thesis to address potential stability problems that may occur during gradual raisings and under seismic loading conditions of Aitik tailings dam in northern Sweden. The dam is mainly raised using upstream construction method. It is planned to raise the dam gradually in several stages. Two dam parts were studied. The first dam part is a straight dam portion, and the second dam part is a corner. The main concerns associated with future raisings of the straight dam part were: (i) the stability of the dam could be affected by an increase in excess pore pressures during sequential raisings, (ii) how to gradually strengthen the dam by using rockfill berms as supports in such a way that required slope stability can be achieved with a minimum volume of rockfill berms, and (iii) if the dam is subjected to seismic loading, whether or not an increase in excess pore pressures could lead to extensive liquefaction which may cause a failure. The problems related to the dam corner were that tension zones and/or low compression zones could develop because of the horizontal pressure of the stored tailings on the inside of the curvature of the dam corner.Numerical analyses were conducted on both the dam parts using finite element method. Two dimensional (2D) plane strain finite element model was utilized to analyse the straight dam. The dam corner was analysed with both the three dimensional (3D) finite element model, and the 2D axisymmetric finite element model. Coupled deformation and consolidation analyses, and slope stability analyses were performed on both the dam parts to simulate gradual raisings, and to compute safety factors. In addition to this, dynamic analyses were carried out on the straight dam part to evaluate the potential for liquefaction, and seismic stability of the dam. The seismic behaviour of the dam was analysed for two cases: (i) a normal case (earthquake of 3.6 Swedish local magnitude), and (ii) an extreme case (earthquake of 5.8 moment magnitude).The results of the straight dam part, with only previously existing rockfill berms, indicate that stability of the dam was reduced due to an increase in excess pore pressures during raisings. Rockfill berms were utilized as supports to raise the dam with enough safety. An optimization technique was utilized to minimize the volume of rockfill berms. This technique could result in significant saving of cost of rockfill berms.The results of the dam corner show that tension zones and/or low compression zones were located on the surface of the dam corner, mainly above the phreatic level. It is interpreted that there is no risk of internal erosion through the embankments because no seepage path occurs above the phreatic level, and a filter zone exists along the slope of the dam. It is suggested to gradually strengthen the dam corner with rockfill berms. The results of the 2D axisymmetric analyses of the dam corner were in a fairly good agreement with those of the 3D analyses. This implies that the 2D axisymmetric analyses are valid for this dam corner. This is an important finding as 2D axisymmetric analyses require much less computational time compared to 3D analyses.The results of the dynamic analyses performed on the straight dam (including additional rockfill berms) suggest that, for the extreme case, liquefaction could occur in a limited zone that is located below the surface near the embankments. For both the normal and the extreme case, (i) seismically induced displacements seem to be tolerable, and (ii) the post seismic stability of the dam is considered to be sufficient.The findings of this study have been practically applied to the Aitik tailings dam. In general, the modelling procedure and the optimization technique to minimize volume of rockfill berms, presented in this study, could be applied to other tailings dams. / Godkänd; 2013; 20130513 (muhauc); Tillkännagivande disputation 2013-05-20 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Muhammad Auchar Zardari Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Numerical Analyses of Stability of a Gradually Raised Tailings Dam Opponent: Professor Daichao Sheng, School of Engineering, The University of Newcastle, New South Wales, Australia Ordförande: Professor Sven Knutsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 13 juni 2013, kl 10.00 Plats: F1031, Luleå tekniska universitet

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