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1
Lund, Cecilia. "Mineralogical, chemical and textural characterisation of the Malmberget iron ore deposit for a geometallurgical model". Doctoral thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16819.
Testo completoAbstract (sommario):
The northern Norrbotten ore province is an intensely mineralised area and has traditionally been a very important mining district. It contains Fe, Cu-Au, Au, and Ag deposits ranging from world-class ore deposits to small and uneconomic ones (Martinsson 2004). The most important are the Kiruna and Malmberget iron ores and the Aitik Cu-Au deposit.The cross-discipline approach called geometallurgy connects two different but closely related areas in the mining industry, namely geology and mineral processing. It involves understanding and measurements of the ore properties significant for its successful processing. Geometallurgy takes both the geological and mineral processing information to create a spatially-based (3D) predictive model for product management in mining operations (Lamberg, 2011).This case study investigates how to establish a geometallurgical model using the Malmberget iron ore deposit as a case study. A mineralogical approach (Lamberg 2011) was selected meaning that the focus is on mineralogy, and therefore parameters like modal mineralogy, mineral textures, mineral associations, mineral grain sizes and their relation to liberation characteristics are important. The main effort is to deliver a geological model which gives quantitative rather than descriptive information to be used in a process submodel.The ore characterisation (Papers I and II) gives new information on the chemical composition of minerals, mineralogical composition of both ore and host rocks, as well as the variation within the individual ore bodies. This sets a firm basis for the quantitative methods developed for routine analysis of modal mineralogy (Paper III) and mineral textures (Paper IV). Also, this increases the understanding regarding the primary origin and metamorphic evolution of the deposit, which is important since the origin of the apatite iron ore of the Kiruna type is still controversial.Based on the modal composition, preliminary geometallurgical (GEM) ore types were established for the Malmberget ore body. Each of these GEM-types describes quantitatively: the minerals present, their chemical composition, rules how to calculate the modal composition from routine chemical assays (element to mineral conversion, EMC rules) and a textural archetype in a library of archetypes. Using these GEM-types it is possible to calculate the modal mineralogy and the liberation distribution for every geological unit from the sample level to GEM-types to be further used in building a GEM block model of the ore.The applicability of the geological model was tested by developing a liberation based process model of simple one stage dry magnetic separation for the GEM-types. The model returns the metallurgical response, in terms of grade and recovery, of each of the developed GEM-types. The model was validated with another ore sample representing the same archetype from a different ore body and with a different grade. The model forecasted the recovery and concentrate grade within 2%-unit accuracy.This is the first published study where a full predictive geometallurgical model is entirely based on the mineralogy. The approach is a generic approach and valid not only for iron ores but also for other metallic mines.Godkänd; 2013; 20130422 (luncec); Tillkännagivande disputation 2013-08-13 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Cecilia Lund Ämne: Malmgeologi/Ore Geology Avhandling: Mineralogical, Chemical and Textural Characterisation of the Malmberget Iron Ore Deposit for a Geometallurgical Model Opponent: Professor emeritus Terje Malvik, Department of Geology and Mineral resources Engineering, NTNU, Trondheim, Norway Ordförande: Professor Pertti Lamberg, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 6 september 2013, kl 10.00 Plats: F531, Luleå tekniska universitet
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Edfelt, Åsa. "Geology, alterations and mineral chemistry of the Tjårrojåkka Fe-oxide Cu-Au occurrences, northern Sweden". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26616.
Testo completoAbstract (sommario):
The Tjårrojåkka area is located about 50 km WSW of Kiruna, northern Sweden, and hosts one of the best examples of spatially related Fe-oxide Cu-Au occurrences (the Tjårrojåkka-Fe and Tjårrojåkka-Cu). The bedrock, depositional environment and tectonic evolution of the area were studied through petrological, geochemical and geophysical-petrophysical investigations. The bedrock is dominated by intermediate and basic extrusive and intrusive rocks. The intermediate andesites and basaltic andesites are cut by diabases which acted as feeder dykes for the overlying basalts. The intrusive rocks range from gabbro to quartz-monzodiorite in composition. The area is metamorphosed to epidote-amphibolite facies and has been affected by scapolite, K-feldspar, epidote and albite alteration that is more intense in the vicinity of deformation zones and mineralisations. Based on geochemistry the andesites and basaltic andesites are similar to the Svecofennian Porphyrite Group intermediate volcanic rocks, but have also features common with the intermediate volcaniclastic unit in the underlying Kiruna Greenstone Group. Chemically the basalts and diabases have the same signature, but cannot directly be correlated with any known basaltic unit. Some of the samples have characteristics comparable to the basalts of the Kiruna Greenstone Group. Whether the volcanic sequence at Tjårrojåkka represents the Porphyrite Group or is part of the greenstones could not be unequivocally determined without geochronological data. Three events of deformation have been distinguished in the Tjårrojåkka area; the first one involving NW-SE compression creating NE-SW-striking steep foliation corresponding with the strike of the Tjårrojåkka-Fe and Cu bodies, followed by the creation of an E-W deformation zone. Finally a second compressional event resulted in folding and the formation of a NNW-SSE striking and gently dipping structure possible related to thrusting from SW. The Tjårrojåkka apatite-magnetite ore (52.6 Mt of iron ore @ 51.5% Fe) is a blind ore consisting of a massive magnetite core surrounded by an ore- breccia containing low-grade Cu-mineralisation. Apatite, amphiboles and carbonate occur disseminated and as veins within the massive ore and in the wall rock. The Tjårrojåkka-Cu mineralisation is located 750 m from the Tjårrojåkka-Fe and contains 3.23 Mt ore @ 0.87% Cu. The main ore minerals are chalcopyrite and bornite occurring both disseminated and in veinlets. Minor pyrite, molybdenite and gold have also been observed. The host rock has been affected by strong albite, scapolite, amphibole and K-feldspar alteration. The alteration assemblages at Tjårrojåkka are highly variable with several of the alteration minerals occurring in several generations and settings, and with multiple reactivations of already existing veins and overlapping alteration stages indicating a complex, long history of fluid activity in the area. Similarity in alteration minerals and paragenesis in the iron and copper mineralisation is described in terms of whole rock geochemistry, mineral chemistry and paragenesis. This may partly be explained by the common host rock to the mineralisations, but indicates also similarities in fluid composition. Within the massive magnetite ore apatite, tremolite and carbonate veinlets fill fractures probably formed during cooling of the magnetite body. The wall rock has been affected by extensive pervasive albite and plagioclase alteration. Scapolite occurs locally as porphyroblasts and later veins. The albitised and scapolitised rocks are overprinted by pervasive K-feldspar alteration and veins of K-feldspar + Mg-hornblende ± titanite ± quartz ± magnetite ± sulphides along the foliation. Epidote is common in veins together with K-feldspar. Allanite occurs as an accessory mineral associated with epidote, otherwise REE-minerals are rare. Carbonate and zoelites were the last phases to form in vacancies. The area between the apatite-iron and copper bodies is strongly albite + magnetite altered. The footwall of the copper body is characterised by pervasive albite alteration spatially associated with magnetite and apatite veins cut by later carbonate veinlets. Scapolite (porphyroblasts and veins) is formed in an early stage in the hanging wall overprinted by pervasive K-feldspar alteration. Amphiboles (tschermakites, Mg-hornblende and actinolite) occur in several generations as porphyroblasts, in veins on its own, or together with K-feldspar ± titanite ± quartz ± carbonate ± chalcopyrite ± bornite. Epidote, REE- carbonate, zeolites and fluorite are the latest alteration phases in the copper mineralisation. Ba, Cl, S and F are enriched in the alteration minerals in the Tjårrojåkka occurrences. Barium-rich varieties of K-feldspar (max. 3.5% BaO) occur in the Cu-mineralised breccia surrounding the apatite-magneitie body indicating high concentrations of Ba in the hydrothermal fluids. Absence of sulphate in the fluids probably caused the formation of Ba-feldspars instead of barite. Scapolite shows a trend with more Cl-rich varieties around the magnetite body gradually getting more SO3 and CO2-rich in the Cu-mineralisation. The presence of accessory barite in the copper mineralisation also indicates that the SO3 content in the fluids were higher than in the iron ore. The biotites are rich in Ti while Cl and F contents are more moderate and do not show great variation in different parts of the systems. All amphiboles are Ca-rich ranging from tschermakites, Mg-hornblende to actinolite and tremolite. The apatites are F-dominate with higher Cl content in the apatite- iron ore than in the copper occurrence. Overall the alteration minerals related to the apaite-iron ore are more rich in Cl and Ba than the ones in the Cu-mineralisation that show higher contents of F, SO3 and CO2.Godkänd; 2003; 20070215 (ysko)
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Kampmann, Tobias Christoph. "3D structural framework and constraints on the timing of hydrothermal alteration and ore formation at the Falun Zn-Pb-Cu-(Au-Ag) sulphide deposit, Bergslagen, Sweden". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26483.
Testo completoAbstract (sommario):
The Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base and minor precious metal sulphide deposits in Sweden. Host rocks to the deposit as well as the ores and altered rocks were metamorphosed and affected by heterogeneous ductile strain during the Svecokarelian orogeny the total duration of which was 2.0–1.8 Ga. These processes both reworked the mineral assemblages of the original hydrothermal alteration system and reshaped the structural geometry of the deposit, following formation of the ores and the associated hydrothermal alteration.In order to study primary geological and ore-forming processes at Falun, it is necessary firstly to investigate the nature of the tectonothermal modification. In this licentiate thesis, a three-dimensional modelling approach is used in order to evaluate geometric relationships between lithologies at the deposit. This study demonstrates the polyphase character (D1 and D2) of the strong ductile deformation at Falun. The major rock-forming minerals in the silicate alteration rocks are quartz, biotite/phlogopite, cordierite, anthophyllite, chlorite, and minor almandine and andalusite. On the basis of microstructural investigations, it is evident that these minerals grew during distinct periods in the course of the tectonic evolution, with major static grain growth between D1 and D2, and also after D2. Furthermore, the occurrence of F2 sheath folds along steeply south-south-east plunging axes is suggested as a key deformation mechanism, forming cylindrical, rod-shaped ore bodies which pinch out at depth. The sheath folding also accounts for the same stratigraphic level (footwall) on both the eastern and western sides of the massive sulphide ores. A major, sulphide-bearing high-strain zone defines a tectonic boundary at the deposit and bounds the massive sulphide ores to the north.The geological evolution in the Falun area involved emplacement of felsic sub-volcanic intrusive and volcanic rocks and some carbonate sedimentation; followed by hydrothermal alteration, ore formation and the intrusion of dykes and plutons of variable composition after burial of the supracrustal rocks. Secondary Ion Mass Spectrometry (SIMS) U-Pb (zircon) geochronology of key lithologies in and around the Falun base metal sulphide deposit indicates a rapid sequence of development of different magmatic pulses with individual age determinations overlapping within their uncertainties. The intense igneous activity, as well as the feldspar-destructive hydrothermal alteration and ore formation are constrained by two 207Pb-206Pb weighted average (zircon) ages of 1894 ± 3 Ma for a sub-volcanic host rock not affected by this type of alteration and 1891 ± 3 Ma for a felsic dyke, which cross-cuts the hydrothermally altered zone and is also unaffected by this alteration. All other ages, including the granitic plutonic rocks, fall in the interval between these ages.The lithological, structural and geochronological observations have implications for the environment and the conditions of ore formation at the Falun deposit. Several aspects argue for an ore system resembling a classic volcanogenic massive sulphide (VMS) system in terms of type of alteration, metal zonation, the pyritic character of massive sulphides and an inferred vent-proximal location in relation to the convection-driving magmatic system. The bowl-shaped, sub-seafloor feeder part of such a system might have served as an initial inhomogeneity in the strata for the later development of strong stretching along steep axes and sheath fold formation during ductile strain. Possible discordant relationships along the margins of the massive sulphide ores, coupled with the syn-magmatic, pre-tectonic timing of ore formation are in accordance with a general VMS-type model for the Falun base metal sulphide deposit. These results provide a compromise solution to the previous debate around two opposing models of strictly syn-genetic vs. epigenetic, post-deformational carbonate-replacement processes for ore formation at the deposit.The Falun pyritic Zn-Pb-Cu-(Au-Ag) sulphide deposit, situated in the Palaeoproterozoic (1.9–1.8 Ga) Bergslagen lithotectonic unit in the south-western part of the Fennoscandian Shield, is one of the major base and minor precious metal sulphide deposits in Sweden. Host rocks to the deposit as well as the ores and altered rocks were metamorphosed and affected by heterogeneous ductile strain during the Svecokarelian orogeny (2.0–1.8 Ga). These processes both reworked the mineral assemblages of the original hydrothermal alteration system and reshaped the structural geometry of the deposit, following formation of the ores and the associated hydrothermal alteration.In order to study primary geological and ore-forming processes at Falun, it is necessary firstly to investigate the nature of the strong tectonothermal modification. In this licentiate thesis, a three-dimensional modelling approach is used in order to evaluate geometric relationships between lithologies at the deposit. This study demonstrates the polyphase character (D1 and D2) of the ductile deformation at Falun. The major rock-forming minerals in the silicate alteration rocks are quartz, biotite/phlogopite, cordierite, anthophyllite, chlorite, and minor almandine and andalusite. On the basis of microstructural investigations, it is evident that these minerals grew during distinct periods in the course of the tectonic evolution, with major static grain growth between D1 and D2, and also after D2. Furthermore, the occurrence of F2 sheath folds along steeply south-south-east plunging axes is suggested as a key deformation mechanism, forming cylindrical, rod-shaped ore bodies which pinch out at depth. The sheath folding also accounts for the same stratigraphic level on both the eastern and western sides of the massive sulphide ores. A major, sulphide-bearing high-strain zone defines a tectonic boundary inside the deposit and bounds the massive sulphide ores to the north. A precursor to this zone can have played a central role as a metal-bearing fluid conduit during ore genesis, prior to reactivation of the zone in the ductile regime.The geological evolution in the Falun area involved emplacement of felsic volcanic and sub-volcanic rocks and some carbonate sedimentation, followed by ore formation and hydrothermal alteration as well as the intrusion of dykes and plutons of variable composition. U-Pb zircon geochronology of key lithologies in and around the Falun base metal sulphide deposit indicates a rapid sequence of development of different magmatic phases with individual age determinations overlapping within their uncertainties. The igneous activity is constrained between a zircon U-Pb concordia age of 1899 ± 7 Ma for a sub-volcanic host rock and a zircon 207Pb-206Pb weighted average age of 1891 ± 3 Ma for a felsic dyke, with all other reliable ages, including the quartz-rich plutonic rocks, falling in the interval between them. This interval also included the hydrothermal alteration and ore formation at Falun.It is suggested that the bowl-shaped, sub-seafloor feeder part of a high-sulphidation and Au-bearing volcanogenic massive sulphide ore system, with replacement of carbonates and (sub)-volcanic rocks, served as an initial inhomogeneity in the strata for the later development of strong stretching along steep axes and sheath fold formation during ductile strain. The observation of discordant relationships along the margins of the massive sulphide ores, coupled with the syn-magmatic, pre-tectonic timing of ore formation, corroborate this hypothesis, providing a compromise solution to the previous debate around two opposing models of strictly syn-genetic vs. epigenetic, post-deformational carbonate-replacement processes of ore formation at the Falun base metal sulphide deposit.
Godkänd; 2015; 20150212 (tobkam); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Tobias Christoph Kampmann Ämne: Malmgeologi/Ore Geology Uppsats: 3D Structural Framework and Constraints on the Timing of Hudrothermal Alteration and Ore Formation at the Falun Zn-Pb-Cu-(Au-Ag) Sulphide Deposit, Bergslagen, Sweden Examinator: Professor Pär Weihed Institutionen för samhällsbyggnad och naturresurser, Avdelning Geovetenskap och miljöteknik, Luleå tekniska universitet Diskutant: Docent, adjungerad professor Pietari Skyttä, University of Turku, Department of Geography and Geology, Turun Yliopisto, Finland Tid: Torsdag 23 april 2015 kl 10.00 Plats: F531, Luleå tekniska universitet
Structural evolution, hydrothermal alteration and tectonic setting of the Falun base metal and gold deposit, Bergslagen region, Sweden
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Bauer, Tobias. "Structural and sedimentological reconstruction of the inverted Vargfors basin : a base for 4D-modelling". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17596.
Testo completoAbstract (sommario):
The Palaeoproterozoic Skellefte mining district in northern Sweden covers an area of 120 by 30 km and is one of the most important mining districts in Europe, producing mainly Zn, Cu, Pb, As and Au from volcanogenic massive sulfide (VMS) and orogenic gold deposits.Detailed mapping of structures and stratigraphy within the sedimentary Vargfors Group combined with a structural analysis revealed a syn-extensional fault pattern of NW-SE-trending normal faults and associated NE-SW-trending transfer faults, creating the segmented sedimentary Vargfors basin. It comprises distinct fault-bound compartments, which incluence the sedimentary stratigraphy in each of these compartments.Syn-rift subsidence affected the sedimentary conditions from near-shore to shallow submarine environment.Intensive fault movements associated with mafic volcanic activity along these faults resulted in the rapid uplift of the oldest phase of the Jörn intrusive complex and/or subsidence of its surrounding areas. Subsequent erosion of the intrusive rocks led to the formation of a tonalite to granodiorite bearing conglomeratic sequence, representing an alluvial fan. Further uplift to the north of the district resulted in the erosion of Arvidsjaur volcanic rocks and the formation of a braided river system. Subsidence of the intrusive complex and/or a sedimentary coverage on top of the same caused a break in sedimentation of tonalite to granodiorite clasts. Stratigraphical evolution of the sedimentary rocks and the Vargfors Group - Skellefte Group contact relationships show that rifting started in the centre and proceeded with time towards SE and NW. Subsequent basin inversion resulted in the reactivation of the existing normal faults along a carbonate-rich basal layer forming asymmetric synclines. Primary geometries of sedimentary strata within each fault-bound compartment controlled their deformation styles. Furthermore, strain was partitioned into the faults, forming high strain zones along the basin margins, where foliations parallel the main faults, and low strain domains in the core of the basin, where foliation is oblique to the main structural grain of the basin. This oblique foliation is either a result of a rotating stress field or a transpressional regime. This case study on basin inversion gives implications for accretion processes along the Svecokarelian Craton margin as well as forthe formation of VMS-deposits and their possible transposition. Basic modelling of the main geological boundaries in the central Skellefte district was performed by integrating data from regional to outcrop scale using the GoCAD (Paradigm) software platform. Available data included geographical and geological data, which were imported from ArcGIS (ESRI) as well as drill-hole data, seismic profiles, resistivity and gravimetry profiles and EM-profiles. Creation of the main geological boundaries utilized GoCAD and SPARSE (Mirageoscience) algorithms, whereas structural geological data was exclusively modelled with SPARSE. Furthermore, this study provides a base for refining the 3-dimensional model and developing a 4-dimensional model, showing the geological evolution of the Skellefte district.Godkänd; 2010; 20101029 (tobbau); LICENTIATSEMINARIUM Ämnesområde: Malmgeologi/Ore Geology Examinator: Professor Pär Weihed, Luleå tekniska universitet Diskutant: Dr Peter Sorjonen-Ward, GTK, Kuopio, Finland Tid: Torsdag den 16 december 2010 kl 10.00 Plats: F531, Luleå tekniska universitet
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Bark, Glenn. "Genesis and tectonic setting of the hypozonal Fäboliden orogenic gold deposit, northern Sweden". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17200.
Testo completoAbstract (sommario):
The well-known Skellefte Ore District, northern Sweden, hosts a large number of massive sulphide deposits, a few porphyry-type-deposits and a number of gold deposits in different geological settings. Southwest of this district a new ore province, the so called Gold Line, is presently being uncovered. During the past decade a number of gold occurrences have been discovered in this area. Only one deposit is in production, the Svartliden gold deposit (2 Mton at 4.3 ppm Au). However, with regards to tonnage the Fäboliden gold deposit stands out with a known mineral resource of c. 16 Mton with 1.33 ppm Au. Additional 24.5 Mton with 1.5 ppm Au is indicated down to a depth of 350 m. The late- to post-orogenic, c. 1.81-1.77 Ga, Revsund granite constitutes the main rock type in the Fäboliden area and surrounds a narrow belt of metavolcanic rocks and metagreywackes. The metasedimentary rocks are strongly deformed, within a roughly N-S trending subvertical shear zone, with boudinaged competent horizons that indicate E-W shortening and a suggested dextral sense of shear within the shear zone. The mineralization at Fäboliden constitutes a 30-50 m wide, N-S striking, steeply dipping ore zone. The mineralization is commonly hosted in arsenopyrite-bearing quartz-veins, which parallel the main foliation, within the metagreywackes in the shear zone. The fine-grained (2-40 µm) gold is closely associated with arsenopyrite-löllingite and stibnite and found in fissures and as intergrowths in the arsenopyrite-löllingite. Gold is also seen as free grains in the silicate matrix of the metagreywacke host rock. Microprobe analysis shows that the gold occurs as electrum (Au:Ag 2:1). The proximal ore zone display enrichment in Ca, total S, As, Ag, Au, Sb, Sn, W, Pb, Bi, Cd, Se, and Hg, whereas K and Na are slightly depleted. The hydrothermal alteration assemblage in the proximal ore zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. This type of assemblage is commonly recognized in hypozonal orogenic gold deposits worldwide. The c. 1.3 km long ore body (lode) is steeply dipping and known to a depth of 150 m, with a few deeper boreholes indicating a continuation of the mineralization towards depth. The mineralization is also open towards north and south. The fabric that hosts the mineralization is also found in the outer margin of the surrounding Revsund granite. It is therefore suggested that at least the final stages of the gold mineralization are late- or post-orogenic in age, and the maximum age for the mineralization is constrained at c. 1.80 Ga (Revsund age). The mineralizing fluids were composed of CO2-CH4-H2S. Gold, arsenopyrite- löllingite, and graphite were precipitated from this fluid. The crystal structure of the graphite, enclosed in the gold related quartz veins, indicates a maximum temperature of 520-560ºC for the mineralizing event, temperature conditions equal to mid-amphibolite facies. These temperatures indicate pressure conditions of c. 4 kbar for the mineralizing event. During deformation mineralizing fluids are often concentrated into deformation zones. Therefore, the potential for economic mineralization in the Lycksele-Storuman region is regarded as very high since the initial results from this project have indicated the existence of several larger ductile to semi-ductile shear zones and accompanied silica alteration in the studied area. During 2004 the project strongly assisted in locating a new gold target in the Gold Line area. For more effective future exploration in this area a better understanding of the structural conditions and evolution is a key factor.Godkänd; 2005; 20061214 (haneit)
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Martinsson, Olof. "Bispbergs järnmalmsfält : En geologisk och geokemisk studie". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 1987. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26303.
Testo completo
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Amoorizi, Varnamkhasti Kianoosh. "Competitive Business framework design toward the circular economy". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86977.
Testo completo
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Tollefsen, Elin. "Chemical controls on ikaite formation". Licentiate thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-156839.
Testo completo
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Moberg, Jesper. "Naturliga halter av metaller i sjöar och vattendrag med avseende på lokal geologi i Barseleområdet". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353770.
Testo completoAbstract (sommario):
Bakgrundshalter för olika metaller i svenska sjöar och vattendrag stämmer inte alltid överens med geologin i lokala områden, som kan ha anrikats många gånger högre än beräknade halter i jordskorpan. Detta är fallet i Barseleområdet, norra Sverige där Agnico Eagle genomför undersökningsarbeten med fokus på guld. Syftet med arbetet är att undersöka vad som anses vara naturliga halter av metaller i området med avseende på lokal geologi och jämföra dessa med bedömda bakgrundshalter. Fokus ligger på metallerna arsenik, antimon, bly och zink där även dess geokemiska beteende undersöks. Vattendata från vattendrag och sjöar från tio lokaler i området kring fyndigheten under perioden 2001–2016 har bearbetats. Analyserna har gjorts med analyspaket V2 (grundämnen i sötvatten). Bakgrundshalter har erhållits från SLU och Sveriges miljöinstitut som jämförts med vattendata från området. Resultaten visar att arsenik och antimon har genomgående högre halter än beräknade bakgrundshalter, där antimon, bly och zink generellt ligger i linje med bakgrundshalterna beroende på klassning av vattnet. Faktorer som pH, hydrologiska förhållanden samt löslighet och rörlighet i vatten visar sig ha stor påverkan på om halterna av metaller kommer överskrida bakgrundshalterna. Adsorption till järnoxider är ett exempel på en faktor som påverkar metallers rörlighet i vatten, och därmed om de kommer anrikas eller inte.The levels of metals measured in individual Swedish lakes and waterways (local scale) do not always correspond to levels expected from knowledge of the underlying geology (regional scale), and in some cases can be orders of magnitude higher than expected. This is the case in the Barsele area, northern Sweden, where Agnico Eagle are exploring for gold. The purpose of this work is to investigate the natural levels of metals in waters with regard to local geology in the area, and compare these with calculated background levels. The study focuses on the metals arsenic, antimony, lead and zinc, and their geochemical behavior. Water data from ten sites during 2001–2016 have been studied. The analyzes were carried out with V2 analyzing package. Background levels were obtained from SLU and Sweden's environmental institute, which have been compared with water data from the area. The results show that arsenic and antimony have consistently higher levels than calculated background levels, while levels of lead and zinc generally correspond to background levels, depending on the classification of the water. Factors such as pH, hydrological conditions, and solubility and mobility in water have a major influence on whether or not the levels of metals exceed the calculated background levels. Adsorption to iron oxides is an example of a factor that decreases the mobility of metals in water.
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Sarlus, Zimer. "Geochemical and geochronological constraints on 1.88 and 1.80 Ga magmatic events in the Gällivare area, northern Sweden". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25689.
Testo completoAbstract (sommario):
The Gällivare area is situated in northern Norrbotten, Sweden, and hosts the Aitik Cu-Au deposit and the Malmberget Fe deposit. In addition, more than 17 mineral prospects and mineralizations are present, among these the currently developed Nautanen Cu-Au deposit. All deposits are hosted within Paleoproterozoic volcanic and volcano-sedimentary successions intruded and surrounded by multiple generations of intrusive suites, including large bodies of ultramafic to mafic layered complexes. Detailed field mapping combined with geochemical and petrological investigations and geochronology have revealed suites of igneous rocks ranging in composition from ultramafic-mafic, intermediate to felsic. Main key igneous rocks include 1) tholeiitic, ultramafic-mafic layered intrusive complexes; 2) calc-alkaline mafic to intermediate plutonic and volcanic units; 3) calc-alkaline, mafic-intermediate dykes and sills; 4) calc-alkaline and shoshonitic granitoids. U-Pb multigrain zircon SIMS analysis combined with lithogeochemical investigations suggest two magmatic episodes at 1.88 and 1.80 Ga, respectively, with coeval mafic-felsic magmatism including the generation of voluminous layered complexes. Based on their MORB-type, tholeiitic character, these layered complexes are suggested to have formed in an extensional setting, preferentially in a back-arc environment. U-Pb multigrain zircon SIMS analysis and field mapping also reveal that granitoids in the area range from 1886 to 1779 Ma with the oldest granitoids containing mafic enclaves. This suggests magma interaction between basic and felsic magma sources. Geochemical data suggest generation of granitoids in a volcanic arc environment in a mainly post-collisional setting. Results suggest the formation of layered complexes and a volcanic arc system in an extensional setting followed by a subsequent compressional phase of arc accretion producing post-collisional granitoids. The 1.88 Ga event that generated the ultramafic-mafic layered complexes is associated with a back-arc setting generated in response to 1.90 Ga NNE trending subduction. The later event at ~1.80 Ga generating voluminous mafic-felsic units is associated with the TIB event which is also coupled to the regional IOCG overprint.The Gällivare area is situated in northern Norrbotten, Sweden, and hosts the Aitik Cu-Au deposit and the Malmberget Fe deposit. In addition, more than 17 mineral prospects and mineralizations are present, among these the currently developed Nautanen Cu-Au deposit. All deposits are hosted within Paleoproterozoic volcanic and volcano-sedimentary successions intruded and surrounded by multiple generations of intrusive suites, including large bodies of ultramafic to mafic layered complexes. Detailed field mapping combined with geochemical and petrological investigations and geochronology have revealed the role of intrusive igneous events and their control on ore formation. Main key igneous rocks include 1) tholeiitic, ultramafic-mafic layered intrusive complexes; 2) calc-alkaline mafic to intermediate plutonic and volcanic units; 3) calc-alkaline, mafic-intermediate dykes and sills; 4) calc-alkaline and shoshonitic granitoids. U-Pb multigrain zircon SIMS analysis combined with litho-geochemical investigations suggest two magmatic episodes at 1.88 and 1.80 Ga, respectively, with coeval mafic-felsic magmatism including the generation of voluminous layered complexes. Based on their MORB-type, tholeiitic character, these layered complexes are suggested to have formed in an extensional setting, preferentially in a back-arc environment. U-Pb multigrain zircon SIMS analysis and field mapping also reveal that granitoids in the area range from 1886 to 1779 Ma with the oldest granitoids containing mafic enclaves. This suggests magma interaction between basic and felsic magma sources. Geochemical data suggest generation of granitoids in a volcanic arc environment in a mainly post-collisional setting. Results suggest the formation of layered complexes and a volcanic arc system in an extensional setting followed by a subsequent compressional phase of arc accretion producing post-collisional granitoids. The 1.88 Ga event that generated the ultramafic-mafic layered complexes is is associated with a back-arc setting generated in response to 1.90 Ga NNE trending subduction. The later event at ~1.80 Ga generating voluminous mafic-felsic units is associated with the TIB event also coupled to the regional IOCG overprint.
Godkänd; 2016; 20160518 (zimsar); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Zmar Sarlus Ämne: Malmgeologi /Ore Geology Uppsats: Geochemical and Geochronological Constraints on 1.88 and 1.80 Ga Magmatic Events in the Gällivare Area, Northern Sweden Examinator: Biträdande professor Christina Wanhainen, Institutionen för samhällsbyggnad och naturresurser, Avdelning: Geovetenskap och miljöteknik, Luleå tekniska universitet. Diskutant: PhD Paul Evins, WSP Sverige AB, Stockholm. Tid: Fredag 17 juni, 2016 kl 10.00 Plats: F341, Luleå tekniska universitet
11
Mattsson, Tobias. "En petrologisk studie av lavor och en mantelxenolit från Fogo, Kap Verde". Thesis, Uppsala universitet, Berggrundsgeologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-185139.
Testo completoAbstract (sommario):
Alla Kap Verdes öar är av vulkaniskt ursprung. Fogo är den enda ön i Kap Verdes arkipelag som fortfarande är vulkaniskt aktiv, med 30 registrerade utbrott sedan människor bosatte sig på ön för cirka 500 år sedan. Detta gör Fogo till en av de mest aktiva vulkanerna på jorden. Fogos lavor är viktiga att studera för att få en förståelse för vulkanens magmasystem och förhindra framtida katastrofer. Lavorna är mörka och innehåller mycket fenokryster utav olivin och clinopyroxen, och i enstaka prover hittas apatit (inneslutningar i pyroxener) och amfibol. Den petrografiska undersökningen tyder på att lavorna är basaniter eller melanonefeliniter. På Fogo förekommer både Pahoehoe- och Aa- lavor. En mantelxenolit ger insikt till lavornas ursprung. Den studerade xenoliten har en protogranulär textur och består främst av olivin (Fo86-88) med mindre förekomster av ortopyroxen, clinopyroxen och phlogopitaggregat. Clinopyroxenfenokrysterna i lavorna är mineralet diopsid (MgCaSi2O6). Fosterithalten i olivinfenokryster är (Fo81-84). Zonering på kristaller visar magmaevolutionen vid ett utbrott. Zoneringen i clinopyroxenfenokrysten är i kärnan av kristallen omvänd och övergår sedan till normal. Det vill säga till en början en ökning av MgO för sedan minska mot fenokrystens kant. Detta tyder på att fenokrysterna började kristallisera samtidigt som ny smälta tillfördes för att sedan övergå till en fraktionering av magman. En ökning av MgO på ytterkanten av fenokrysten kan tyda på att en primitiv smälta tillförts magman. Xenoliten har sitt ursprung under Moho på ett maximalt djup av 270 km.
12
Oxenstierna, Johan. "Remote Sensing and Statistical Analysis of Fracture Populations Around Lake Thingvallavatn, SW Iceland". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182201.
Testo completoAbstract (sommario):
This study aims at a description and statistical analysis of tectonic and magmatic fractures in the Western Volcanic Zone (WVZ) on Iceland. Two fracture populations are studied with respect to their distance to the Hengill volcano: The southern area is between 0-10 kilometers from the volcano and the northern area is between 16-25 kilometers from the volcano. The description and analysis of fractures is carried out separately for the two areas as well as for the two areas together to test different mapping procedures, statistical methods and the influence of the volcano on the properties of the fractures. There are various reasons for considering this an important study: Firstly, this is not an extensively researched field and there are many unanswered methodological questions on how to map and describe the fractures. In this study, problems such as how maps are stitched and georeferenced, how fractures are divided into segments and mapped in respect to topography, are discussed. The potential errors caused by these methodological problems are concluded to be large enough to significantly affect statistical tests analyzing fracture populations. In the analysis part, the properties of the fracture populations are studied using Kolmogorov Smirnov and χ 2 goodness-of-fit tests, scatter-plots, simple count and ratios among other methods. It was found that the fracture populations follow distributions that are not easily defined, but that they are of the same and quantifiable type. With more data their common distribution could therefore be modeled, and the factor by which the Hengill volcano affects the strike of fractures per distance unit from the volcano could be calculated. It was also found that magmatic fractures are formed in a similar, but not necessarily the same stress-field as tectonic fractures. Therefore change in magma pressure might change the local stress regime around magmatic fractures, affecting their strike.
13
Andersson, Barbro. "Pressure-Temperature Estimates on the Tjeliken Eclogite from Northern Jämtland, Swedish Caledonides". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196118.
Testo completoAbstract (sommario):
Eclogites are important in order to understand orogenic processes, since their presence indicates high-pressure metamorphism. In northern Jämtland, Swedish Caledonides, eclogites have been found at several places in the Seve Nappe Complex (SNC). The mountain Tjeliken in the Lower Seve Nappe is one of them. Dating relates the high-pressure metamorphism to the Late Ordovican subduction of the Baltoscandian margin during the closure of the Iapetus Ocean. In this study new P-T conditions are presented for the Tjeliken eclogite based on petrographical and geochemical studies of an eclogite sampled on the top of Tjeliken in summer 2010. Peak assemblage consists of garnet + omphacite + phengite + quartz. New peak conditions are calculated to c. 2.7 GPa and 700°C. These P-T conditions are in the upper part of the quartz stability field, close to the quartz - coesite stability line. The new P-T conditions correspond well to other P-T calculations of eclogites in northern Jämtland and indicate a deep subduction of the Baltoscandian margin already in the Late Ordovician.
14
Karlsson, Pia. "Sulfidmineral i Salatrakten : med en introduktion i opakmikroskopi". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196982.
Testo completoAbstract (sommario):
Sala är beläget i Bergslagen och bergarterna hör därmed till den svekofenniska berggrunden. Berggrunden domineras av 1.9-1.87 Ga sedimentära-, vulkaniska- och metamorfa bergarter. Vad man vet idag har metamorfosen i Bergslagen skett vid temperaturer på 500-650 ºC och på ett djup av 10-15 km. Salas berggrund är till stor del uppbyggd av karbonater, hälleflinta, kvartsdioritporfyrit, granofyr och granit. Karbonatstenen är till största delen magnesiumrik och övervägande dolomitisk till sammansättningen. Ett mer än 300 meter mäktigt dolomitlager innehåller Sala gruvas zink- och silvermalmer. I sydost begränsas dolomiten av graniter och i väster av hälleflintor. Sala gruvas primära malmmineral är järnrik zinkblände, magnetkis, blyglans, magnetit och pyrit. Viktiga associations- och spårmineral är bland annat kopparkis, gudmundit, molybdenglans, boulangerit, diaforit, freibergit och mineral tillhörande Ag-Hg-Sb systemet. Sju polerprover från Salaområdet analyserades med hjälp av reflektionsmikroskop och två dessutom med elektronmikrosond. Blyglans detekterades i alla prover. Zinkblände, pyrit och tetrahedrit återfanns i 6 av 7 prover, rent silver hittades i ett prov från Stenhavet och magnetkis hittades i alla prover från Stensbotten. Kopparkis, AgHg-amlagam och magnetit kunde ses i cirka hälften av proverna. Gudmundit återfanns i två av proverna plockade vid Stensbotten och två av proverna tros innehålla molybdenglans. Ett av proverna undersökt med WDS-analys innehåller ren antimon samt tre andra antimon- och silvermineral. Metamorf påverkan har diskuterats från de texturella sambanden.
15
Magnusson, Johan. "Jordens metallresurser : En kort överblick över våra viktigaste industrimetaller och deras bildningssätt". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-211080.
Testo completoAbstract (sommario):
Metaller och gruvdrift är ett ständigt aktuellt ämne. Återanvändning av metaller blir allt viktigare då metaller betraktas som en ändlig resurs. Men är de verkligen det, och i sådana fall: ur vilket perspektiv? Arbetet behandlar bildningsprocesser för några av våra viktigaste metaller - guld, järn, nickel och koppar - samt en handfull sällsynta metaller vars användning ökat: indium, gallium och germanium. Arbetet börjar med att kortfattat diskutera begreppen malmer och mineral. Därefter beskrivs de processer som enligt rådande vetenskaplig teori ligger till grund för de viktigaste av dessa malmförekomster. Där behandlas även tidsbegreppet för malmbildande processer. Beräknade tillgångar på dessa metaller i dagsläget, samt beräknade reserver tas också upp. Vidare diskuteras prisutvecklingen på dessa metaller och avslutningsvis förs ett resonemang kring prisutveckling med fokus på den globala marknaden och tillväxtekonomierna i Kina, Ryssland, Indien och Brasilien samt andra mindre men likväl växande ekonomier i världen.
16
Martinsson, Evy. "Lainijaurintrusionens geokemi : En geokemisk studie av sidoberget till Lainijaur Ni-Cu malm". Licentiate thesis, Luleå tekniska universitet, 1987. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16889.
Testo completo
17
Andersson, Joel. "Structural evolution of two ore-bearing Palaeoproterozoic metasupracrustal belts in the Kiruna area, Northwestern Fennoscandian Shield". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72034.
Testo completoAbstract (sommario):
In this project, two key study areas in the northwestern Fennoscandian Shield are under investigation. The “Western supracrustal belt” and “Central Kiruna area” are both located along lithotectonically comparable Rhyacian-Orosirian metasupracrustal belts and both areas are characterized by iron oxide-apatite (IOA) and iron oxide-copper-gold (IOCG)-style mineralizations and related hydrothermal alterations. The area is in general well studied but the structural evolution remains unresolved. In order to build a structural framework for the Kiruna area, the number of deformation events, kinematics, geometries, mineralogy and interrelationships of the dominant structures are under focus in this study. The paired structural-alteration configuration is targeted in order to constrain the relative timing of dominant structures and mineral alteration parageneses in order to use these systems as structural vectors of mineralized systems. Furthermore, the Orosirian stratigraphy is re-evaluated in order to constrain the pre-compressional geological history of the study areas. This is important as it controls the character of the structural development during subsequent compression forming the sub-surface architecture as we see today. The Orosirian stratigraphy suggests the development of a syn-extensional basin in Kiruna where iron oxide-apatite deposits were emplaced. This basin was subsequently inverted accompanied by shearing, folding, and faulting during D1 and D2, refolded during D3, and further fractured during D4. The shortening directions inferred during the deformation events suggest a clockwise rotation of the stress field from NE-SW (D1) to E-W (D2) and finally NNW-SSE (D3). Regional scapolite ± albite alteration is interpreted to be coeval with regional amphibole + magnetite alteration during D1. Mineral alteration parageneses linked to D2 is more potassic in character and often structurally controlled by shear zones. As a regional generalization, the potassic dominated D2-alteration is characterized by sericite ± epidote ± biotite ± chlorite ± magnetite ± sulphide ± K-feldspar. Fe- and Cu-sulphides are concentrated into brittle D2-structures suggesting that a IOCG-style of mineralization can be linked to the potassic D2 event. This implies that iron oxide-apatite emplacement can be linked to the basin development phase, whereas epigenetic Fe- and Cu-sulphides are linked to the basin inversion-phase of the geological evolution, and hence, separated in time and probably not directly genetically linked in Kiruna.
18
Sädbom, Stefan. "Metamorfos och malmbildning i Enåsens guldgruva Hälsingland". Thesis, Uppsala universitet, Geologiska institutionen, 1987. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-442799.
Testo completoAbstract (sommario):
Some parts of the mineralogy and the petrology of the Enåsen gold-deposit, northern Hälsingland, Sweden are described. The gold in Enåsen is extracted from a sillimanite-rich quartzite. The rocks in the stratigraphic foot-wall of the ore are described as a part of a stratigraphic column. It is suggested that the sillimanite-quartzite is a part of an overturned stratigraphic sequence. The temperature and the pressure during the main metamorphose is determined to 620-670º C and 5-6.5 kbar by use of the mineral paragenesis and the graphite geothermometer. It is shown that the ores are of epigenetic origin and it is suggested that the different ores were formed by one continous ore-forming process. The earlier stages of the ore-formation were caracterized by a relatively homogeneous infiltration of the ore-bearing fluids. During the late stage of the ore formation, the ore-bearing fluids were restricted to localized veins. These veins are now recognized as grey sillimanite-rich veins surrounded by sulphides and as calcite-altered veins with sulphides. It is also suggested that the presence of graphite in the undermost stratigraphic level of the foot-wall reduced the water-molefraction which directly caused the deposition of the sulphides and the gold.
19
Minz, Friederike. "Mineralogical characterisation of the Rockliden antimony-bearing volcanic-hosted massive sulphide deposit, Sweden". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17621.
Testo completoAbstract (sommario):
Rockliden is a polymetallic Zn-Cu volcanic-hosted massive sulphide (VHMS) deposit. It is located in north-central Sweden about 150 km south of the Skellefte ore district. Two major challenges to mining and production were identified soon after Rockliden was discovered in the 1980’s. Firstly, the geographic distance to Boliden’s main ore deposits and existing concentrator in the Skellefte district will set additional financial and logistic constrains for the processing of the ore. Secondly, the locally high Sb grade in the ore potentially lowers the quality of the Cu-Pb concentrate sent to the Cu smelter. To face the second challenge to mining and production, it is necessary to use information from three disciplines: ore geology, mineral processing and process metallurgy. The three disciplines build the geometallurgical framework of the Rockliden ore characterisation. The purpose of this investigation is to outline which mineralogical factors are the cause of the elevated Sb content in the Cu-Pb concentrate. Determining such factors will help to predict the Sb content of this product and thus outline the tools required before decisions may be reached with regard to selection between various processing alternatives for the Rockliden ore. Hydrometallurgical treatment of the Cu-Pb concentrate has previously been studied by Awe (2013) and it was found that alkaline sulphide leaching can be used to lower the Sb content.A qualitative characterisation of the ore forms the main focus of this licentiate thesis. Minerals have been identified and their chemical composition has been obtained with micro-analytical tools (SEM/EDS & EPMA/WDS) to study the mineralogical distribution of major (e.g. Zn, Cu, Fe), penalty (e.g. Sb) and bonus (e.g. Ag) metals. Furthermore, mineral textures and associations have been studied in ore samples by optical microscopy and SEM/BSE imaging. Ore types are preliminary classified based on the sulphide mineralogy, i.e. the relative content of pyrite, pyrrhotite, magnetite, sphalerite and chalcopyrite estimated by reflected light microscopy. As sphalerite and chalcopyrite form the main Cu- and Zn-bearing minerals at Rockliden, the content of these two minerals can be approached with element-to-mineral conversion based on standard drill core assays (including S, Cu, Zn, Pb, As, Sb and Ag). The mineralogy of Sb-bearing minerals is complex and a single thin section can contain more than three different Sb-bearing phases. Thus, the element-to-mineral conversion is not applicable in directly calculating the modal mineralogy of the Sb-bearing mineral fraction based on drill core assays. Additionally, it is shown that the mineral association of the Sb-bearing minerals is complex. Products from initial flotation tests have been studied and the preliminary conclusion is that the complex intergrowths with various minerals influence the distribution of Sb-bearing minerals between the flotation products. Thus, a more detailed petrographic study on the massive sulphides and their host rocks was conducted. The sulphide and non-sulphide mineralogy of the host rocks and ore types are shown to be variable. It is also shown that the host rock types can be distinguished based on their trace element eochemistry, supporting the geological classification based on drill core logging.Based on petrographic and mineralogical observations done in this study, potential process-relevant rock-intrinsic factors are outlined. However, to evaluate the impact of such parameters on the beneficiation process, these parameters have to be quantified throughout the Rockliden deposit and this is the focus of continued studies. SEM-based automated mineralogy tools will be essential in measuring the important parameters such as modal mineralogy and mineral liberation. Quantitative information will then be used in a larger framework to build a geometallurgical model usable for production planning.Godkänd; 2013; 20131021 (frimin); Tillkännagivande licentiatseminarium 2013-11-22 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Friederike Elisabeth Minz Ämne: Malmgeologi/Ore Geology Uppsats: Mineralogical Characterisation of the Rockliden Antimony-Bearing Volcanic-Hosted Massive Sulphide Deposit, Sweden Examinator: Associate Professor Christina Wanhainen, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Associate Professor Kurt Aasly, Department of Geology and Mineral Resources Engineering, NTNU, Trondheim, Norway Tid: Måndag den 16 december 2013 kl 10.00 Plats: F341, Luleå tekniska universitet
20
Patten, Clifford G. C. "Mobility of gold and other metals during alteration of the oceanic crust : Implications for the formation of VMS deposits". Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-132782.
Testo completoAbstract (sommario):
Tremendous physical and chemical exchanges occur along oceanic ridges between the lithosphere, the hydrosphere and the biosphere. During these exchanges important mobilisation of metals by hydrothermal fluid circulation takes place within the oceanic crust. Volcanogenic massive sulphide (VMS) deposits are hydrothermal ore deposits rich in Cu-Zn-Pb bearing sulphide minerals that form during submarine venting of these hydrothermal fluids near the seafloor. A proportion of the metals enriched in these deposits are mobilised from deeper crustal levels during high-temperature hydrothermal alteration. Gold-rich VMS deposits represent an important sub-set of VMS deposits that are enriched in Au and related elements such as As, Sb, Se and Te. The processes that form Au-rich VMS are still debated, due in part to our lack of understanding of the behaviour of these elements during formation and alteration of the oceanic crust. In this thesis we carry out a systematic investigation into the behaviour of Au, As, Sb, Se and Te during evolution of the oceanic crust. Three localities are studied: the Ocean Drilling Program (ODP) Hole 1256D in the Cocos plate, the Troodos ophiolite in Cyprus and the ODP Hole 786B in the Izu-Bonin forearc. The investigation has been carried out using cutting-edge analytical techniques including ultra-low detection limit analyses of Au and other metals in rock samples. The objectives of the thesis are 1) to quantify the mobilisation of metals including Au, related elements As, Sb, Se and Te and base metals during the alteration of the oceanic crust; 2) to determine the mineral reactions which promote this mobilisation; 3) to investigate the variability in metal mobility in different tectonic settings in the oceanic crust and 4) to investigate the extent to which the composition of “source area” oceanic crust controls the composition of VMS deposits in different tectonic settings. The main outcomes of this study are fourfold. 1) The distribution of Au and related elements in primary crust varies considerably between different tectonic settings. Sulphide minerals play an important role in the behaviour of Au, Se and Cu during magmatic differentiation and hydrothermal alteration, but have a lesser influence on other metals. The oxidation state of the primary crust controls whether sulphide minerals are present, and thus is an important control on the budget and mobility of strongly chalcophile metals during hydrothermal alteration. 2) Large masses of Au and related elements are mobilised from the sheeted dyke complex in mid-oceanic ridge (MOR) and ophiolite settings. Significantly more metals are mobilised from the source areas than are trapped in the VMS deposits observed in these settings. Therefore, most of the metals mobilised from the source areas are lost, either during transport, venting, sedimentation or late fluid mobilisation. 3) Insufficient Au is mobilised from MOR settings at ODP Hole 1256D to form Au-rich VMS deposits. The quantity of Au mobilised from the Troodos ophiolite could potentially lead to Au-rich VMS formation but additional processes such as vapour separation by sub-seafloor boiling or magmatic volatile input would be required to increase the Au : base metal ratio. The lack of evidence for these processes in Troodos implies that Au-rich VMS deposits are not likely to be abundant in this area. 4) Isotopic and trace element evidence supports magmatic input in the hydrothermal system at ODP Hole 786B, implying that magmatic fluid input into hydrothermal systems leaves a specific signature which can be tracked.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.
21
Metzger, Nicolai. "Structural controls on the shear zone hosted, IOCG-style Kiskamavaara Cu-Co-Au mineralization". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74068.
Testo completoAbstract (sommario):
Sweden is the largest producer of iron ore in the European Union, as well as amongst the top producers for base and precious metals. Much of its mineral wealth derives from northern Norrbotten, type locality of the Kiruna-type-magnetite-apatite ores. Besides the massive iron ore bodies, the region is further recognized as important iron-oxide-copper-gold (IOCG) province, with the world class, Aitik Cu-Au-Ag-(Mo) deposit as its most prominent example (1061 Mt with 0,22% Cu; 0,15ppm Au; 1.3ppm Ag), (Wanhainen et al. 2012, Boliden 2017). The close spatial relation between Aitik, further IOCG style mineralization and the Nautanen Deformation Zone (NDZ), a crustal-scale, approximately N-S trending shear system provides important insights into the complex connection between deformation, reactivated fault systems and the different mineralizing events affecting the area during the Svecofennian period (1.9-1.8 Ga). Whereas this connection is well constrained within the Gällivare mining district (c.f. Martinsson and Wanhainen 2004, Wanhainen et al. 2012, Bauer et al. 2018, Lynch et al. 2018), the northern and southern continuations of the NDZ and its potential to host further mineralization remain unknown. During this study, an area around the Kiskamavaara Cu-Co-Au mineralization was investigated to link its tectonic evolution with regional metallogenic events and compare its alterations and structural regime to that of the highly prospective NDZ. It is suggested that the region was affected by at least two deformation events, D1 and D2, both causing a characteristic alteration assemblage, structural patterns and related mineralization. The identification of pseudotachylitic structures and supergene mineralization argues for a late, brittle, upper crustal event with hydrothermal character during D2. Constraining the Kiskamavaara Cu-Co-Au mineralization to this event allows to propose a genetic link to the known IOCG-style mineralization in the Nautanen area that are generally related to a late, 1.80 Ga period of hydrothermal activity. It is suggested that the Cu-Au mineralization in the Kiskamvaara and Nautanen area formed under similar conditions, hence arguing for a single high strain zone in favor over several locally constrained zones of crustal weakening. If supported in further studies, this finding of a highly prospective NDZ beyond its known extend, might justify more intense exploration in highly strained lithologies between the Kiskamavaara and Nautanen area, as well as north of Mattavaara and south of Gällivare.
22
Möne, Cecilia. "Glacial lake deposits in Kerlingarfjöll, Central Iceland". Thesis, Uppsala universitet, Institutionen för geovetenskap, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-393047.
Testo completoAbstract (sommario):
The extent of glacial lake sediments found north of the Kerlingarfjöll mountains in central Iceland has been determined and their formation in an ice dammed lake is suggested. The damming ice moved from an ice divide in the south-east highlands and was divided into two ice lobes by the Kerlingarfjöll mountains. In an early stage the lake was dammed between the two ice lobes but as they retreated the glacial lake was enlarged in the eastern part where it in the later stage was dammed by topography. The ice dammed lake was almost filled with sediments before it drained to the west when the western ice lobe retreated. The ice dammed lake was contemporaneous with the Hvítárvatn ice dammed lake which was dammed between the western ice lobe and the hills below the Langjökull glacier.Utbredningen hos glaciolakustrina sediment som påträffas norr om fjällklasen Kerlingarfjöll på centrala Island har fastställts och det föreslås att de avsatts i en isdämd sjö. Inlandsisen rörde sig från en isdelare i sydost och flödet delades i två lober vid Kerlingarfjöll. I ett tidigt stadium dämdes sjön upp mellan dessa lober, men när isranden drog sig tillbaka utvidgades sjön i den östra delen och dämdes där av ett topografiskt hinder. Issjön var praktiskt taget fylld med sediment innan den dränerades när den västra isloben drog sig tillbaka. Issjön i Kerlingarfjöll var samtida med Hvítárvatn-issjön som dämdes upp mellan den västra isloben och sluttningarna upp mot glaciären Langjökull.
23
Swärd, Henrik. "The deglaciation of southern central Sweden reflected in the seismic and sedimentary stratigraphy of southern Lake Vättern". Licentiate thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-113498.
Testo completo
24
Jonsson, Linus. "Seismic tomography as an instrument for structural evaluation in the Printzsköld and Alliansen ore bodies, Malmberget". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64918.
Testo completoAbstract (sommario):
The Malmberget deposit is one of the major apatite iron ores in Europe, located in northern Norrbotten. As the mining in Malmberget proceeds deeper more challenges with the stability have been faced. When the stress distribution of a rock mass exceeds the rock strength energy in form of seismic waves is released. In Malmberget, a monitoring system consisting of 200 geophones is installed which detects all seismic waves in the area. Based on data received from the monitoring system, LKAB has achieved to generate a seismic tomography model over the velocity variations of the seismic waves as they propagate in the rock mass. The present study evaluates how the seismic tomography model can be used as a tool for reconstructing the structural characteristics of the two ore bodies Printzsköld and Alliansen. The aim is to clarify how seismic tomography can be combined with structural data to increase the geological knowledge of the Malmberget mining area. Based on structural measurements from the mine in combination with geotechnical data (RQD, Jr, Ja) two structural geological models were constructed. One model visualizing the orientation of the foliation and the other presenting brittle joints and fractures. The models were constructed in order to compare them with the seismic tomography model to outline structures and characteristics in the rock mass. The foliation in Printzsköld has a steep NE-SW orientation. In the eastern part where Printzsköld connects to Alliansen, the orientation changes to NW-SE, indicative of a fold structure. The joints and fractures in the study area appeared as 4 sets. One set appeared parallel to the foliation and one perpendicular to it. The two other sets were oriented E-W almost perpendicular to each other with a shallow dip. The rock quality in Printzsköld shows a pattern of increasing quality deeper down with zones of lower quality following the magnetite ore body. The previous identified deformation zone DZ031 appear as an important structure for unstable zones in Printzsköld. The current results suggest that the seismic tomography model needs more investigation but shows promising results as an indicative instrument delineating large scale structures and large zones with lower rock quality.Gruvan i Malmberget är belägen i norra Norrbotten och utgör en av de största apatitjärnmalmerna i Europa. Med tiden försätter brytningen i Malmberget på allt större djup. Det innebär en större utmaning med stabiliteten i gruvan då spänningarna i berget kan tänkas öka längre ner. När bergsspänningarna överskrider bergets hållfasthet sker en frigörelse av energi i form av seismiska vågor. I Malmberget finns ett system av 200 geofoner som detekterar alla seismiska vågor i området. Baserat på data som mottagits från övervakningssystemet har LKAB lyckats framställa en seismisk tomografimodell över de seismiska vågornas hastighetsvariationer när de breder ut sig i bergmassan. I studien granskas hur den seismiska tomografin kan användas som ett verktyg för att utvärdera geologiska strukturer i de två malmkropparna Printzsköld och Alliansen. Syftet är att klargöra om seismisk tomografi kan kombineras med strukturdata för att öka den geologiska kunskapen i Malmbergets gruvområde. På basis av mätta strukturer i gruvan i kombination med geoteknisk data (RQD, Jr, Ja) konstruerades två strukturgeologiska modeller i syfte att jämföra modellerna mot den seismiska tomografin. Resultatet från studien visar att foliationen i Printzsköld har en NÖ-SV orientering med en brant stupning. I den östra delen som förbinder till Alliansen ändras orienteringen succesivt till NV-SÖ, vilket indikerar en veckning av foliationen. De dominerande riktningarna för sprickor och frakturer i Printzsköld och Alliansen uppträdde som 4 set. Ett set var orienterat parallellt med foliationen och ett vinkelrätt mot det förevarande. De två andra sprick riktningarna var orienterade Ö-V nästintill vinkelrätt mot varandra med en flack stupning. Bergskvalitén i Printzsköld visade ett mönster av att förbättras djupare ner. Zoner med lägre bergskvalité följer malmkroppen. Den seismiska tomografin uppvisade korrelation med storskaliga strukturer samt stora områden med minskad berghållfasthet. Den tidigare identifierade deformations zonen DZ031 uppträder också som en viktig struktur instabila områden i Printzsköld. Utvärderandet av resultaten tyder på att den seismiska tomografin behöver fortsatt mer undersökningsarbete men visar lovande resultat av att fungera som ett vägledande instrument för att definiera storskaliga strukturer och större områden med sämre bergskvalité.
25
McClay, K. R. "Structural geology and tectonics /". Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09SD/09sdm126.pdf.
Testo completo
26
Myers, Edwin Carl. "Constructing a creationist geology". Portland, Or. : Theological Research Exchange Network (TREN), 2005. http://www.tren.com.
Testo completo
27
Riccomini, Claudio. "O Rift Continental do Sudeste do Brasil". Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/44/44136/tde-18032013-105507/.
Testo completoAbstract (sommario):
O Rift continental do Sudeste do Brasil (RCSB), de idade cenozóica, é uma feição alongada e deprimida, desenvolvida entre as cidades de Curitiba (PR) e Niterói (RJ), numa extensão de pelo menos 800 km. Segue grosseiramente a linha de costa atual, da qual dista em média cerca de 70 km, alcançando o Atlântico na sua terminação nordeste. O segmento mais contínuo desse rift, entre as cidades de São Paulo (SP) e Volta Redonda (RJ), com cerca de 350 km de comprimento, foi objeto de estudo no presente trabalho, no tocante aos seus aspectos de tectonia e sedimentação. Com base principalmente na análise microestrutural e na análise de fácies sedimentares, amparadas em dados mineralógicos, palinológicos, geocronológicos e geomorfológicos, entre outros, pôde ser estabelecida de forma tentativa, a seguinte seqüência de eventos para a área estudada: a) Paleógeno (Eoceno-Oligoceno): formação da depressão original (hemi-graben), contínua na porção analisada, como resultado do campo de esforços extensionais de direção NNW-SSE imposto pelo basculamento termomecânico na Bacia de Santos; preenchimento vulcano-sedimentar sintectônico (Grupo Taubaté), compreendendo um sistema de leques aluviais associados à planície aluvial de rios entrelaçados (Formação Resende), basal e lateral na bacia, um sistema playa-lake (Formação tremembé), e um sistema fluvial meandrante (Formação São Paulo); eclosão de derrames de basanito a sudeste de Volta Redonda (Basanito Casa de Pedra), associados ao sistema fanglomerático; condições climáticas inicialmente semi-áridas, durante a sedimentação das formações Resende e Tremembé, passando para úmidas durante a deposição da Formação São Paulo; b) Neógeno (Mioceno ?): transcorrência sinistral de direção E-W, com extensão NW-SE e localmente compressão NE-SW; geração de soleiras (Arujá, Queluz, entre outras) relacionadas à transpressão, ou bacias tipo pull-apart (sistema fluvial entrelaçado da Formação Itaquaquecetuba), associadas à transtração ou relaxamento final dos esforços dessa fase; separação das drenagens dos rios Tietê e Paraíba do Sul pela Soleira de Arujá, com mudança do nível de base e erosão na porção central da Bacia de Taubaté; c) Plioceno (?) a Pleistoceno Inferior: implantação de novo sistema fluvial meandrante (Formação Pindamonhangaba), na área da Bacia de Taubaté, em condições provavelmente quentes e úmidas; d) Pleistoceno Superior: inicialmente fase de estabilidade tectônica com a deposição de sedimentos colúvio-aluviais, frutos do remodelamento do relevo em função das variações climáticas; ao final, nova fase transcorrente E-W, agora dextral, com compressão NW-SE e geração de novas soleiras; definição de distribuição atual dos sedimentos nas bacias, ou embaciamentos, num arranjo lazy-Z; e) Holoceno: nova extensão NW (WNW) - SE (ESE), afetando depósitos de baixos terraços ligados à evolução da rede de drenagem do Rio Paraíba do Sul; f) Atual: campo de tensões indicando compressão, sugestivo de nova mudança no regime de esforços. A alternância entre transcorrência sinistral e dextral e, conseqüentemente, de esforços trativos para compreensivos, respectivamente, estaria relacionada provavelmente ao balanço entre as taxas de abertura na Cadeia Meso-Atlântica e de subducção da Placa de Nazca sob a Placa Sul Americana. A deriva desta última para oeste, em relação às estruturas antigas do RCSB, proporcionaria transcorrência dextral quando a taxa de abertura excedesse a de subducção e transcorrência sinistral no caso oposto. O quadro tectono-sedimentar estabelecido apresenta implicações para a geologia econômica e de engenharia da área de estudo, sendo apresentadas breves considerações a esse respeito ao final do trabalho.The Continental Rift of Southeastern BraziI (CRSB), of Cenozoic age, is an elongate, narrow trough more than 800 km long, between the cities of Cutiriba (Paraná State) and Niterói (Rio de Janeiro State). It roughly parallels the present-day coastline, reaching the Atlantic Ocean in the northeast. The segment of the rift located between the cities of São Paulo (S. Paulo State) and Volta Redonda (Rio de Janeiro State) was the objetc of tectonic and sedimentary analysis. As a result of microstructural analysis, and the study of sedimentary facies, supported by mineralogical, palynological, geochronological, geomorphological and other data, it was possible to reconstruct the Tertiary-Quaternary tectonic and sedimentary history of the study area as follows: a) Palaeogene (Eocene-Oligocene): formation of the original depression (half-graben), continuous over the entire study area, as a result of NNW-SSE extension related to thermomechanical tilting of the adjoining offshore Santos Basin; syntectonic volcanism and sedimentation (Taubaté Group) with a basal and marginal alluvial fan/fluvial braided system (Resende Formation), a playa-lake system (Tremembé Formation), and an upper fluvial meandering system (São Paulo Formation); basanite lava flows, southeast of Volta Redonda (Casa de Pedra Basanite), associated with the Resende Formation; paleoclimatic conditions initially semi-arid during the deposition of the Resende and Tremembé Formations, gradually becoming humid during the sedimentation of the São Paulo Formation; b) Neogene (Miocene ?): Ieft-lateral E-W transcurrence, with NW-SE extension and local NE-SW compression; generation of structural highs (Arujá, Queluz and others) related to transpression, and pull-apart basins (fluvial braided system of the Itaquaquecetuba Formation) associated with transtension or final relaxation of the stress of this phase; separation of Tietê and Paraíba do Sul drainage systems by the Arujá Structural High, with changes in base level and consequent erosion in the westcentral part of the Taubaté Basin; c) Pliocene (?) - Early Pleistocene: installation of a new fluvial meandering system (Pindamonhangaba Formation) in the Taubaté Basin, probably under warm and humid paleoclimatic conditions; d) Late Pleistocene: initially tectonic stability with the deposition of colluvium and alluvium related to morphogenetic evolution as a function of climatic changes; at the and of epoch renewed E-W transcurrent phase, now right-lateral, with NW-SE compression; generation of new structural highs; surface distribution of sedimentary deposits in a lazy-Z pattern; e) Holocene: extensional NW (WNW) - SE (ESE) regime affecting low terrace deposits related to the evolution of the Paraíba do Sul drainage system; f) Present-day: compressive stress-field, suggestive of a new change in the stress regime. The alternation from sinistral to dextral transcurrence is probably related to the interplay between the rates of opening along the Middle Atlantic Ridge and subduction of the Nazca Plate beneath the South American Plate. The effect of westward drift of the South American Plate on the NE-trending basement structures of the CRSB has generated dextral transcurrence when the expansion rate in the east has exceeded the subduction rate in the west and sinistral transcurrence in the opposite case. This tectono-sedimentary picture has significant implications for the economic and engineering geology of the study area, especially with respect to neotectonics and mineral exploration.
28
Kiani, Tayebeh. "Modeling for geospatial database : application to structural geology data : application to structural geology data". Paris 6, 2010. http://www.theses.fr/2010PA066057.
Testo completoAbstract (sommario):
L’objectif de cette étude est de créer un modèle de base de données dans un système d’information géographique afin d’archiver, analyser, présenter et de diffuser des données observées lors des analyses de géologie structurale. Le modèle de données est conçu pour atteindre quatre objectifs: établir un vocabulaire partagé par les spécialistes, modéliser les concepts de géologie structurale, produire des cartes dérivées des cartes géologiques d’Iran et fonctionner avec un logiciel de système d’information géographique. Un ensemble de classes conceptuelles est alors identifié pour représenter les concepts de base de la géologie structurale pour les objets contacts, plis, foliations, fractures (failles et joints), linéations et zones de cisaillement. Un modèle conceptuel unifié est construit pour chaque famille. Puis, le modèle logique de données, présenté en langage UML à l’aide de diagrammes de classes statiques, est développé. Les étapes dans l’élaboration du modèle de données incluent l’identification des classes, la création des diagrammes de classes, la déclaration des attributs et des associations. Les cartes géologiques d’Iran au 1:250 000 sont ici utilisées comme base de présentation d’un modèle conceptuel permettant l’unification et la préparation d’une légende unique d’un ensemble pilote de quatre cartes. Les résultats de l’étude fondent les principaux concepts et les structures des données pour représenter l’information spatiale en géologie structurale et fournissent un modèle pour créer une base de données permettant la gestion des données de géologie structurale avec un système d’information géographique
29
Garrick-Bethell, Ian 1980. "Early lunar geology and geophysics". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/47845.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.Includes bibliographical references.
Despite a number of human and robotic missions to the Moon, there are still important unanswered questions about its early evolution, and how it came to be the object we observe today. Here we use observational, experimental, and theoretical techniques to examine three important events that took place early in lunar history and have left a lasting signature. The first event is the formation of the largest basin on the Moon, the South Pole-Aitken Basin. We develop a systematic method to define the previously unknown boundaries of this degraded structure and quantify its gross shape. We also combine a number of remote sensing data sets to constrain the origin of heat producing elements in its interior. The second event we examine is the evolution of the lunar orbit, and the coupling between the Moon's early geophysical properties and the growth of orbital eccentricity. We use analytical models for tidal deformations and orbit evolution to show that the shape of the Moon suggests its early orbit was highly eccentric. However, we are also able to explain the presently high eccentricity entirely by traditional, secular tidal growth while the early Moon was hot. The third event we examine is the magnetization of lunar samples. We perform extensive paleomagnetic measurements of an ancient, deep-seated lunar sample, and determine that a long-lived magnetic field like that of a core dynamo is the most plausible explanation for its magnetic remanence. In sum, the earliest portion of lunar history has been largely obscured by later geologic events, but a great deal can still be learned from this formative epoch.
by Ian Garrick-Bethell.
Ph.D.
30
Lisle, Richard John. "Techniques of quantitative structural geology". Thesis, University of Birmingham, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446367.
Testo completo
31
Woodworth-Lynas, Christopher M. T. "The geology of ice scour". Thesis, Bangor University, 1992. https://research.bangor.ac.uk/portal/en/theses/the-geology-of-ice-scour(eaa92a2c-71af-4304-b8dd-cfe595160468).html.
Testo completoAbstract (sommario):
Ice scour is the phenomenon that occurs when the keel of a floating mass of ice (iceberg, sea ice or freshwater ice) touches, penetrates and continues to move forward through unlithified seabed or lakebed sediments. The typically curvilinear excavation made by the scouring keel is called a scour mark. Scouring ice keels present logistical problems to the safe installation and operation of, for example, oil and gas production pipelines and power and telecommunication cables in several cold ocean regions. The typical surface morphologies of modern iceberg scour marks on the Labrador continental shelf are described, and mechanisms that operate at or near the sediment surface during the period of ice/seabed interaction are suggested. Scouring action also disturbs sediments beneath the seabed or lakebed. Sub-scour deformation is accommodated by compression and pore space-reduction beneath the scour mark, by corresponding volume increase adjacent to the trough and by folding and faulting. Deformation structures are described from beneath ancient large scale (30-40 m-wide) iceberg scour marks exposed in clays of the former glacial Lake Agassiz in southern Manitoba, and from small scale (< 5 m wide) contemporary scour marks that form on tidal flat sediments in Cobequid Bay, Nova Scotia, and the St. Lawrence estuary, Quebec. Structural data from the Lake Agassiz features are presented and discussed with respect to scour mark-forming mechanisms. Criteria for the recognition of ice scour marks and of ice keel turbates are developed. The criteria are discussed with respect to observations, frequently of striated bedding plane surfaces, contained in the published works of others. The analysis reveals that possible ice scour marks and ice keel turbates may occur in glacimarine and glacilacustrine sediments of Precambrian, Ordovician, Devonian, Carboniferous and Permian age at a number of localities worldwide.
32
FERRARETTI, Denis. "Data Mining for Petroleum Geology". Doctoral thesis, Università degli studi di Ferrara, 2012. http://hdl.handle.net/11392/2389427.
Testo completoAbstract (sommario):
In petroleum geology, exploration and production wells are often analysed
using image logs, because they provide a visual representation of the
borehole surface and they are fundamental to retrieve information on
bedding and rocks characteristics. Aim of this Ph.D. work was to define and
implement a suite of automatic and semi-automatic tools for interpretation
of image logs and large datasets of subsurface data coming from geological
exploration.
This led to the development of I2AM (Intelligent Image Analysis and
Mapping), a semi-automatic system that exploits image processing
algorithms and artificial intelligence techniques to analyse and classify
borehole images. More in detail, the objectives of the I2AM approach are:
(1) to automatically extract rock properties information from all the different
types of data recorded/measured in the wells, and visual features from image
logs in particular; (2) to identify clusters along the wells that have similar
characteristics; (3) to predict class distribution over new wells in the same
area.
The main benefits of this approach are the ability to manage and use a large
amount of subsurface data simultaneously. Moreover, the automatic
identification of similar portions of wells by hierarchical clustering saves a
lot of time for the geologist (since he analyses only the previously identified
clusters). The interpretation time reduces from days to hours and
subjectivity errors are avoided. Moreover, chosen clusters are the input for
supervised learning methods which learn a classification that can be applied
to new wells. Finally, the learned models can also be studied for a cluster
characterization, in a descriptive approach.
33
Tollefsen, Elin. "Thermal and chemical variations in metamorphic rocks in Nautanen, Gällivare, Sweden". Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-149643.
Testo completoAbstract (sommario):
This study focuses on the geology of the Nautanen area. It is part of the SGU-financed project, Metamorphic Map of Sweden, which aims to compile metamorphic data from Sweden and takes the form of a number of Bachelor and Master projects. The main metamorphic event in the Nautanen area is the Svecokarelian Orogeny (1.96 – 1.75 Ga). The samples are metamorphosed sedimentary and volcanic rocks, which were intruded by intermediate to mafic intrusions and a later granite intrusion. The supracrustal rocks are folded and the Nautanen Deformation Zone (NDZ) traverses the area in a NW to SE direction. Petrographic studies, XRF analysis and THERMOCALC were used to estimate pressure and temperature and to elucidate evidence of fluid mobility. The average pressure was assumed to be below 4 kbar because of the presence of andalusite. The lowest and highest temperatures for metamorphism were 474±43°C and 681±14°C, with highest temperatures recorded nearest to the granite intrusion. XRF analysis revealed high concentrations of Ba (up to 7000 ppm) in the NDZ. High concentrations of Ba, skarn formation and replacement of garnet by chlorite indicate fluid-controlled metamorphism in the NDZ. The increasing temperature towards the granite intrusion suggests regional or contact prograde metamorphism that need not be related to the NDZ.Metamorphic Map of Sweden, SGU-project
34
Turner, Tom. "Petrography, alteration and structure of the Bronäs Zn-Pb-Ag deposits, Bergslagen, Sweden". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-78822.
Testo completoAbstract (sommario):
This report aims to characterize the alteration styles and mineralization of the Zn-Pb-Ag Bronäs deposit, in the Sala area of the Bergslagen mining district, Sweden. It presents data collected through 237m of lithological logging and subsequent lithogeochemical data, which, coupled with thin section and SEM analysis has led to the first geological descriptions of the rocks in the deposit. The results are presented in the report through logs and a cross-section interpreted from these logs. The Bronäs deposit, mined between 1945 and 1962, is a satellite deposit to the well-known Sala mine, and similarly to the Sala deposit, it is hosted within an extensive marble unit interbedded with layers of felsic volcaniclastic material. The rocks in the area have first been dolomitized and then undergone regional metamorphism to greenschist facies at 1.87 Ga. There is a large granitic batholith to the south and east of the deposit, and a thin porphyritic intrusion with a complex geometry closely spatially associated with the mineralization. The marble unit is the host unit for the mineralization and is the most commonly occurring rock type in the study area. It is commonly quite impure and variably skarn altered throughout, with common gangue minerals including serpentine, chlorite, tremolite, diopside and phlogopite. The mineralized sections of the marble are spatially related to the skarn-rich areas of marble, and common sulphides include pyrite, galena and sphalerite. The interbedded volcaniclastic beds have a rhyolitic composition, and also contain Mg-silicates such as chlorite, tremolite and phlogopite, giving them a green colour too. The contacts between volcaniclastic and marble beds is often marked by contact skarns. The porphyritic intrusion has a granodioritic composition. It exhibits chilled margins, and the contact between it and the marble is often marked by increased skarn alteration in the marble. The feldspar crystals in the unit are zoned, with a white outer rim and a green to yellow sericitic core. The cross section shows that all the units are steeply dipping to the south-west, with steeply dipping stratabound lenses of mineralization in the marble, sub-parallel to the volcaniclastic beds in the north east. The south-western part of the section is thick uninterrupted marble. Lithogeochemical results have been divided into two groups – a distal group within this thick marble, and a proximal group close to the mineralization and volcaniclastic beds. The proximal zone is enriched in SiO2 and Al2O3 and depleted in FeO, MnO and MgO relative to the distal zone. The Mn and Mg values are enriched when compared to regional levels however. The proximal zone also contains more Pb, Zn, Ag, As and Sb than the distal zone, but contains lower amounts of Au and Cu than the distal zone. There is one hotspot in the distal zone which contains high concentrations of Pb, Zn, Ag, Au, Cu and Sb. The chemical signature is similar to the mined ore at Sala. The common occurrence of Fe, Mg and Mn-bearing skarn minerals near the mineralization suggests these elements should be higher in the mineralized zone, but skarn minerals are common throughout the study area, and the high levels of Si and Al in the mineralization zone could be diluting the other oxides. The lenses of mineralization are closely spatially related to the porphyritic intrusion however the intrusion is relatively minor in terms of size and is younger and unaltered. It could have followed an existing fault which was related to the mineralization though. Various examples of sulphide replacement and retrograde alteration can be seen, such as galena replacing amphiboles and barite. The similarity in mineralogy between regional metamorphic calc-silicates and ore-related skarn minerals makes it hard to differentiate between the two, however the presence of high temperature clinopyroxene indicates the deposit is likely a prograde metasomatic skarn deposit. This is backed up by a similar calc-silicate assemblage, mineralization style and replacement textures to those associated with skarn deposits. It is also spatially related to magmatism with mineralization occurring along lithological contacts.
35
Patch, Nickolas Lee. "Geology of the Dyer Mountain quadrangle, Utah". Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1452.
Testo completo
36
Castro, Ana Marina Escobar [UNESP]. "Depósitos marinhos juro-cretácicos em afloramentos de cuba: nanofósseis calcários e microfácies carbonáticas". Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/102979.
Testo completoAbstract (sommario):
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castro_ame_dr_rcla.pdf: 55950380 bytes, checksum: 297aeb38dae64c995595373122b66a6c (MD5)Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP)
Rochas do Jurássico Superior e Cretáceo, dominantemente carbonáticas e comumente intercaladas a folhelhos e margas, afloram em Cuba central e ocidental. O estudo de 31 afloramentos é o objeto desta tese, que investiga, centralmente, o seu conteúdo nanofossilífero e as características das suas microfácies carbonáticas. Informações quimioestratigráficas de carbono e oxigênio também foram obtidas. O Neojurássico apresenta pobre conteúdo de nanofósseis, freqüentemente mal preservados, seja pela forte recristalização dos calcários seja pela oxidação dos folhelhos, o que impediu seu biozoneamento. Todavia, combinando-se os dados de nanofósseis com os dados paleontológicos prévios (calpionelidos, calcisferas e crinóides da família Saccocomidae) reconhece-se a ocorrência de 4 afloramentos mesothitonianos e 4 neotithonianos. Tais seções neojurássicas teriam sido acumuladas em piso marinho profundo anóxico (rampa externa a batial), conforme sugerem as microfácies dominantemente pelágicas [mudstones, wackestones e margas com radiolários, espículas de esponjas, calcisferas e crinóides (e.g., Saccocoma), equivalentes às microfácies-padrão SMF 1 e SMF 3 de Wilson]. Episódios de aloctonia foram registrados ao longo do intervalo, como sugere a presença de calcários de águas rasas interrompendo a seção pelágica (packstones e grainstones com oóides, pelóides, miliolidos e moluscos). Dados isotópicos de carbono e oxigênio sugerem que águas frias e produtivas estiveram associadas à deposição pelágica. Nos 10 afloramentos pertencentes ao Eocretáceo a nanoflora também é pobre e mal preservada, ocorrendo algumas espécies de forma esporádica ao longo do intervalo. Contudo, foram detectados 9 bioeventos de surgimento ou extinção de espécies de nanofósseis...
Late Jurassic and Cretaceous carbonate rocks and associated marls and shales crop out in central and western Cuba. This thesis objectives, through the study of thirty-one outcrops, to investigate the nannofossil content and carbonate microfacies of these rocks. Also it aims to obtain chemostratigraphic data from carbon and oxygen isotopes. The Late Jurassic has a poor nannofossil content, badly preserved due to the strong limestone recrystallization or to shale oxidation, which obscures the biostratigraphic zoning. However, through the combination of nannofossil and previous paleontologic data (calpionelids, calcispheres and crinoids of the Saccocomidae family), it was possible to recognize the occurrence of four Mesothitonian and four Neotithonian outcrops. Such Late Jurassic sections were accumulated in a deep, anoxic marine environment (outer ramp to bathial), as suggested by the dominant pelagic microfacies [mudstones, wackestones and marls with radiolarians, sponge spicules, calcispheres and crinoids (for instance, Saccocoma), which are equivalent to the Wilsonþs standard microfacies SMF 1 and SMF 3]. Alloctonous episodes were recorded along the interval, as suggested by the presence of shallow water limestones which interrupts the pelagic domain (packstones and grainstones with ooids, peloids, miliolids and mollusks). Carbon and oxygen isotopic data suggest that cold and productive waters were closely associated with the pelagic deposition. In ten Early Cretaceous outcrops the nannoflora is poor and badly preserved, but with sporadic occurrence of some species in the interval. However, nine bioevents of nannofossil appearance or extinction were detected, and when integrated to certain nannofossiliferous associations allowed to recognize... (Complete abstract, click electronic address below)
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Copfer, Torrey J. "Geology of the Deseret Peak East 7.5' Quadrangle, Tooele County, Utah, and Impacts for Hydrology of the Region". DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/6723.
Testo completoAbstract (sommario):
Detailed geologic mapping of the Deseret Peak East 7.5' Quadrangle yields new interpretations regarding the stratigraphy of the Oquirrh Basin, fault and fold geometry, and structural evolution of the region. The Stansbury Range consists of the north-southtrending Deseret anticline. Basal Mississippian units rest unconformably on Cambrian beds in the central part of the range. Paleozoic uplift, Mesozoic contraction, and Cenozoic extension have created a series of broad folds, large thrust faults, and several normal faults.
The area is dominated by bedrock springs, with the presence of abundant and thick Quaternary deposits unrelated to Pleistocene glaciation, burying drainages, and mantling hillslopes. The influence of bedrock on groundwater flow paths and stream baseflow is suggested by local anecdotal reports that high snowfall in the Deseret Peak region generates high discharge ten miles south in Clover Creek, though they are not in the same drainage basin.
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Duber, James R. "Museum of geology for Breezewood, PA: "Studying the role of architecture in the science of geology"". Thesis, Virginia Polytechnic Institute and State University, 1993. http://hdl.handle.net/10919/53347.
Testo completoAbstract (sommario):
People cannot be trained to marvel at landscapes, nor to love their places and their planet. On the other hand, love of place and of the Earth are scarcely sentimental extras to be indulged only when all technical and material problems have been resolved...
The experiences of places, spaces and landscapes in which academic geography originates are a fundamental part of everyone's experience, and geography has no exclusive claim to them. Indeed, one of the first aims of a phenomenology of geography should be to retrieve these experiences from the academic netherworld and to return them to everyone by reawakening a sense of wonder about the Earth and its places. (1.)
Designing a place which reawakens a sense of wonder of the Earth becomes the mission statement for this design thesis: a place which emphasizes the very real and immediate experiences which we share with the land (and landforms) that cannot only support our daily existence, but can soar above us to heights which inspire myth and imagination; a place which uniquely reveals itself to each person promoting personal observations and personal interpretations.Master of Architecture
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Stossel, Deborah Louise. "The engineering geology of Frankton Arm". Thesis, University of Canterbury. Geology, 1999. http://hdl.handle.net/10092/6815.
Testo completoAbstract (sommario):
Seven bedrock landslides situated within quartzofeldspathic schist exist up slope of the residential area along the Frankton Arm of Lake Wakatipu, South Island, New Zealand. Engineering geological and geotechnical failure models for these landslides have been established using engineering geological mapping at scales of 1:5000 and 1:10000, geotechnical testing, and the development of limit-equilibriurn sensitivity models.
Geotechnical testing of artificially fractured schist bedrock obtained shear strength values of Φ = 24°-36° and zero cohesion, and point load strength indexes of 0.6-3.83MPa for rock tested perpendicular to foliation, and 0.11-0.92 for rock tested parallel to foliation. Testing of shear zone material gave values of Φ 60°-110° and zero cohesion.
The largest failure is the Queenstown Hill Landslide, with an estimated volume of 240M m³ which is interpreted as a retrogressive translational landslide with the toe forming a compressional bulge in the mid-slope area of Queenstown Hill. Three phases of movement have taken place, the earliest phase probably being initiated in the southeastern area of the slide mass by ice scouring and the over steepening of slopes during the final stages of the Last Glaciation. On retreat of the glacial ice, lateral support was removed and increased pore water pressures may have acted to reduce the shear strength of the slope along critical failure or shear surfaces. Movement is inferred to have been by translational planar sliding by slow rock mass creep, not from buckling in the toe, partly along foliation shear zones and a stepped failure surface in fractured schist bedrock immediately following glacial retreat.
The second and third phases of movement were initiated as a result of the removal of support by the previous phase, with the second phase forming small translational- slides and. retrogressive features, and the third phase forming the toe bulging by gravitational creep down slope.
Six smaller bedrock failures (up to 2.8M m³ each in volume) are situated further east along Frankton Arm. These landslides are interpreted as shallow retrogressive translational failures, with their slide bases orientated sub-parallel to the schist foliation. These failures may have initially occurred following glacial retreat (similar to the Queenstown Hill Landslide), with the slides situated at lower elevations activated by seismic events at a much later stage following deposition of lake beaches as the enlarged Lake Wakatipu was lowering.
The only evidence for continual movement for within the last 100 years is on Slide No.3 and Slide No.4. Minor wedge failures have occurred from the head scarp, but the high frictional interlock between the displaced blocks creates minimal risk to the residential areas below and if further development was to occur in these areas, prudent engineering geological practices should be implemented.
Future sub-surface work needs to be completed to accurately locate the depth, shape and angle of the failure surfaces for each landslide. This work would also determine the parts of the failure surfaces that occur through foliation shear zones, or fractured schist.
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Tingley, A. C. "Engineering geology of landfill gas migration". Thesis, University of Surrey, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290487.
Testo completo
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Moore, Edwin Neville. "Glacial geology and geomorphology of Weardale". Thesis, Durham University, 1994. http://etheses.dur.ac.uk/1625/.
Testo completo
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Teeling, Michael J. "Geology of Galileo Regio quadrangle, Ganymede". Kansas State University, 1987. http://hdl.handle.net/2097/18557.
Testo completo
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Kneller, Benjamin Charles. "The geology of part of Buchan". Thesis, University of Aberdeen, 1988. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU020384.
Testo completoAbstract (sommario):
The research embodied in this thesis arose from a contract to remap Sheet 87W of the 1:50,000 geological map for the Geological Survey. The rocks investigated include late Precambrian to early Cambrian metasediments of the Dalradian Supergroup, and Caledonian intrusive igneous rocks. The range of sedimentary facies present within the Methlick Formation (Southern Highland Group) is described within the framework of current deep marine clastic facies classifications, and an inner to middle submarine fan facies model erected. Framework petrography, palaeocurrents, geochemistry and facies variation of the Methlick Formation indicate a provenance within the Laurentian shield to the north-west. Analysis of the stream sediment geochemistry dataset acquired by the Geological Survey is used as an aid to stratigraphic correlation in the Dalradian of north-east Scotland. The Ellon Division has middle Argyll Group characteristics, while the Aberdeen Division includes both middle and upper Argyll Group. Rocks with Appin Group geochemistry probably do not crop out in Buchan. Combinations of low-level anomalies for several chalcophile elements may be useful in mineral exploration. Igneous rocks in the Stuartfield area include a wide range of petrographic types of Ordovician age, including previously undescribed Younger Basic cumulates. The area is underlain by a concealed basic intrusion. Contact metamorphic isograds are defined for rocks ranging from andalusite schists to garnet-cordierite gneisses. P and T range up to about 720°C at 4.5kb PH20 falls from near PTOTAL at the K-feldspar isograd to about 0.5 PTOTAL at the garnet-cordierite isograd. A divariant field for coexistence of andalusite and sillimanite is defined, and new occurrences of sapphirine are described. A characteristic upper Argyll Group lithological assemblage in north-east Scotland includes quartzitic and calcareous lithologies, and corundum-bearing pelites with high K and Mg/Fe. Pelites of this assemblage are chemically distinct from those of the Southern Highland Group. The migmatitic gneisses of north-east Scotland, interpreted by some as basement, are in structural, stratigraphic and metamorphic continuity with the Dalradian, and include Argyll Group rocks.
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Kerber, Paulo Augusto. "Granitic series and their economic geology". Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005581.
Testo completoAbstract (sommario):
The granitic rocks are subdivided into four series: tholeiitic, alkaline, calc-alkaline and mobilizates. These series can be formed from melting of mantle material (M-type granites) or from crustal rocks. There are granitic rocks formed from the mixing of these two magmas types. The rocks formed from crustal anatexis are subdivided into those formed from igneous rocks (I-type granites) and those formed from meta-sedimentary rocks (S-type granites). The former has similar characteristics to the mantle-derived granitoids. The mineral deposits related to igneous or mantle derived magma usually are Cu-Au, CUI Cu-Mo, Mo porphyries and have high oxygen fugacity and magnetic susceptibility (magnetite series). The Sn-W deposits usually are related to magma derived from meta-sedimentary or igneous rocks derived magma with low oxygen fugacity and magnetic susceptibility (ilmenite series). According to the tectonic setting, the granitoids rocks are classified as: Andino type, West Pacific type, Hercyno type, Caledonian type and Anorogenic (A-type granites).
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Miller, John Frederick. "Structural geology of the Ohio Shale". Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1163610177.
Testo completo
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Tiedeken, Staci L. "Magnetism and geology of the moon". Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5660.
Testo completoAbstract (sommario):
Since different parts of the Moon display varying magnetic field strengths, our goal was to determine whether these differences are due to specific geological characteristics. We found that older materials tend to be more magnetic than younger materials. Additional statistical studies found that the mare regions of the Moon are less magnetic than the plains and terra regions. We did not find a simple relationship between lunar magnetism and crustal thickness, and this is inconsistent with the hypothesis that thicker crust is more magnetic since there is additional material. Thus, it is not just a matter of the amount of magnetic material that determines the magnetic field strength of the lunar crust. Our results demonstrate that magnetism and crustal thickness have a complex relationship, with multiple distinct groups corresponding to various regions of the Moon. The lunar maria formed a particularly distinct group, consisting of low magnetism and thin crust, while the lunar highlands consist of thick crust but typical magnetic field values.
The ejecta thickness and magnetic field distributions for specific craters showed that larger impact basins have a thicker and more widespread ejecta blanket than smaller craters. We did not find a consistent pattern of magnetic field enhancements near specific craters, but evidence for these strong magnetic signatures was present for Mare Crisium and Mare Nectaris. These results may support the hypothesis that ejecta materials are carriers of magnetism, and this may be the reason for their tendency to have higher magnetic field strengths.
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Harris, William B. "The geologic history of Rock Canyon, Utah : a virtual trip /". CLICK HERE for online access, 2002. http://www.geology.byu.edu/faculty/rah/slides/Rock%20Canyon/Home.htm.
Testo completoAbstract (sommario):
Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2002.Web site works as of 02/10/03. Consult BYU Dept of Geology for URL changes in future. Includes bibliographical references (leaves 8-9). Also available via Internet.
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Key, Heyward M. "Temporal and spatial trends in drilling predation on Crepidula in the U.S. coastal plain /". Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/keyh/heywardkey.pdf.
Testo completo
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Lindelöf, Linnea, e Isabelle Åberg. "Landslide survey, Mamuyod, the Philippines". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-228919.
Testo completo
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Kärrström, Timmy. "From Bedrock to Porcelain : A study regarding the history of porcelain, Ytterby mine and the discovery of yttrium in Sweden". Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-167721.
Testo completoAbstract (sommario):
Porcelain is a translucent vitreous material that consists of clay (kaolin), feldspar and quartz which has been mixed and heated together to cause a metamorphic reaction. In Sweden, the Porcelain industry was established in 1726 at Rörstrands castle in Stockholm and is today one of the oldest industries in Europe to produce porcelain. Around the 1790’s Rörstrand got its feldspars and quartz from the Ytterby mine that was located at Resarö in Stockholm’s archipelago making the raw material somewhat easy to access. Rörstrand owned the mine in the 1850’s to 1926. During the time Ytterby mine was active, an amateur geologist by the name of Carl Axel Arrhenius, discovered an unusual black mineral in the quarry ore in 1787 which later led to the discovery of 8 new rare earth elements (REE) with the help of several Swedish chemists throughout time. These elements are Yttrium, Ytterbium, Gadolinium, Terbium, Thulium, Erbium, Holmium and scandium. This study will focus on the Swedish porcelain industry and how it has evolved throughout history and Rörstrand’s role in the discovery of yttrium.