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Volcanism in Modern Back-arc Regimes and Their Implications for Ancient Greenstone BeltsFassbender, Marc Lorin 21 June 2023 (has links)
Greenstone belts are dominated by volcanic rocks with lithogeochemical characteristics that reflect a range of possible geodynamic settings. Many analogies with modern tectonic settings have been suggested. Increasing exploration and comprehensive sampling of volcanic rocks in modern oceans provides the unique opportunity to characterize different melt sources from intraoceanic settings. This thesis examines geochemical data from more than 2850 submarine mafic and more than 2200 submarine felsic volcanic rocks, representing a wide range of settings. The results show significant geochemical variability spanning the full range of compositions of volcanic rocks found in ancient greenstone belts. This diversity reflects complex rift and spreading regimes, variations in crustal thickness, dry melting versus wet melting, mantle mixing and crustal contamination. Highly variable melting conditions are thought to be related to mantle heterogeneities, complex mantle flow regimes and short-lived tectonic domains, such as those caused by diffuse spreading, multiple overlapping spreading centers and microplate breakouts.
Systematic differences in the volcanic rocks are revealed by a combination of principal components analysis and unsupervised hierarchical clustering. Rocks from most arc-backarc systems have strongly depleted mantle signatures and well-known subduction-related chemistry. This contrasts with rocks in Archean greenstone belts, which show no, or at least weaker, subduction-related chemistry and stronger mantle enrichment resulting from a less-depleted mantle, less wet-melting, and variable crustal contamination. The geochemistry of the modern volcanic rocks reflects lower mantle temperatures, thinner crust and subduction-related processes of present-day settings. However, rocks that are geochemically identical to those in Archean greenstone belts occur in many modern back-arc basins, such as the Lau Basin. Crustal growth and area-age relationships in the Lau Basin are similar to observed ages and compositions of volcanic assemblages in greenstone belts, such as the Blake River Group of the Abitibi Greenstone Belt. Such settings are recognized as favorable locations for volcanogenic massive sulfide (VMS) deposits, and therefore the particular geochemical signatures of the volcanic rocks are important for enhanced area selection in base and precious metal exploration.
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Characterization and Implementation of Ground Tire Rubber as Post-Consumer Polymers for Asphalt ConcreteBaumgardner, Gaylon L 11 December 2015 (has links)
Asphalt binder modification is a common method of improving Hot-mix Asphalt (HMA) performance by enhancing mix properties and reducing or delaying three general HMA distress types: deformation (rutting and shoving), cracking (from repeated loads and low temperatures) and general deterioration (raveling and stripping). Since the early 1960’s, a common modified asphalt alternative has employed reclaimed rubber as an economical and environmental friendly method of recycling waste tires while improving asphalt physical and mechanical properties. Pavement network deterioration combined with increasing material costs makes polymer modification of asphalt binder desirable, with reclaimed rubber from waste tires being an attractive alternative which addresses performance, economics and environmental issues. The primary objective of this dissertation is to demonstrate the importance of proper processing of all types of modified bituminous binders, whether they be virgin (e.g. styrene-butadiene-styrene (SBS) or styrene-butadiene rubber (SBR)), post-consumer polymers (e.g. ground tire rubber (GTR)) or a combination (GTR plus SBS). To achieve this four secondary objectives were identified: 1) characterize GTR using thermo-gravimetric analysis (TGA), 2) improve processing of GTR modified binders, 3) improve testing and specifications of GTR modified binders and 4) evaluate mixes containing GTR modified binders. A simple efficient instrumental, TGA, method to analyze polymers in binary rubber compounds was developed to quantify the functional polymer content available in GTR. TGA analysis provides a better understanding of the general chemical characteristics of GTR used in modification of asphalt binders for production of asphalt paving mixtures. Results are presented from efforts to optimize GTR modified binder formulations with respect to how GTR loading, GTR particle size, processing temperature and asphalt cement source affect modified binder properties and ability to meet performance graded binder specifications. These results are the basis to establish recommended processing parameters for formulation and preparation of GTR modified asphalt binders. GTR modified binders were used in: dense graded asphalt (DGA), stone matrix asphalt (SMA) and open graded friction courses (OGFC) and compared to conventional asphalt cement and styrene-butadiene-styrene (SBS) modified asphalt binders. Mixture performance evaluation with respect to binder effectiveness as it relates to the three general HMA distress types.
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Investigating the potential of systematic optical petrography in a geometallurgical context : A case study on boulder characterization from Rajapalot property, FinlandBjörk, Annie January 2023 (has links)
Geometallurgy describes a holistic approach to mining (integrating geological, metallurgical, geotechnical, environmental, and more parameters) with the goal to improve the efficiency and sustainability of a mining operation. The potential of systematic optical petrography in a geometallurgical context was investigated in this study, as well as how petrography may be useful across disciplines in several blocks of the mining value chain. In a case study, twelve boulder samples (non-mineralized and mineralized) from the Rajapalot exploration property in Finland were characterized by detailed optical microscopy and scanning electron microscopy (SEM) with the aim to delineate the origin of the respective boulders. This allowed to demonstrate some benefits and challenges of systematic optical petrography in the mining value chain and geometallurgical programs. The study was performed through the geology department at Mitta AB in Luleå, Sweden, using rock samples supplied by Mawson Gold Ltd, Finland. The Rajapalot Au-Co property lies a few km east of the Rompas Au-U property, both owned by Mawson Gold Ltd and located in the Paleoproterozoic Peräpohja belt in northwest Finland. When determining the boulders’ origin, geochemical gradients of the Peräpohja belt lithostratigraphy; oxidized sodic rocks in the Kivalo group and reduced potassic rocks in the Paakkola group were crucial factors. The mineralization style of the Rompas Au-U association and the Rajapalot Au-Co association (including the “Palokas” Fe-Mg type and the “Rumajärvi” K-Fe type) were further crucial to classify the mineralized boulders. Results show that the rock types (and suggested origin) vary between boulder samples. Most samples are presumed to originate from the Paakkola group, one sample from the Kivalo group, and a few samples are inconclusive. Furthermore, the samples impact on the mining value chain was discussed based on the results of the petrographic analysis. A method description for a more systematic way of examining rock material is presented, including for example quantitative parameters such asmodal mineralogy and grain size distribution. However, the applicability of this method description needs further study.
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Prezentační pavilon Papírny WANEMI, a.s. v Zábřehu / Presentation pavilion of WANEMI, a.s. paper-mill in ZábřehŘíhová, Helena January 2010 (has links)
The sense of the diploma paper is to make a new entrance - green belt - for the paper factory - WANEMI. There is the exhibition pavillion and the administration building situated in the green belt. The main point of the diploma is the exhibition pavillion. The project is based on the basic principle of ekological architecture like - demounting, using of the waste water and using of the waste warm air. The elementary pavillions´ shape reminds of a paper folder. There are another small exhibitions and constructions in the park. Everything is united by shape and material. The park is the cultural area for sport and education.
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Design and Testing of a Novel Adhesion and Locomotion Method for Wall Climbing VehiclesStefani, Jim R 01 June 2016 (has links) (PDF)
The objective of this project was to design, construct and test a wall climbing vehicle which uses a novel vacuum tread system for both adhesion and locomotion. The design and manufacturing of this proof of concept vehicle is detailed with particular emphasis on the design decisions that proved most impactful to the performance of both the vehicle and the tread system. Adhesion performance was characterized by a series of tests that validate the concept, but also identify improvements and design recommendations for future embodiments of the adhesion/locomotion system.
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Geology of the Tierras Blancas Area in the Southeastern Acambay Graben, Central MexicoMercer, Lonnie T. 30 March 2005 (has links) (PDF)
Pliocene-Pleistocene sediments in the southeastern Acambay graben, central Mexico have yielded mammal fossils, including Equus simplicidens, cf. Rhynchotherium, ?Camelops, Mammuthus sp., Bison sp., and Antilocapra sp. The fossiliferous sediments include a period of lacustrine sedimentation in the late Pliocene-early Pleistocene that interrupted fluvial and alluvial sedimentation during the early Pliocene and Pleistocene. The sediments deposited in this late Pliocene paleolake record a history of lake level fluctuations, shown by lithologic variations in lacustrine sediments and abundance of vertebrate burrows. Volcanic and tectonic events in the Acambay graben were the major controls on sedimentation during Pliocene-Pleistocene time. Various local volcanic structures produced source rocks for Pliocene-Pleistocene sediments, and intra-arc extensional tectonics caused basin subsidence. Blockage of stream drainages by lava flows or perhaps increased basin subsidence contributed to the appearance of and fluctuations in the lacustrine system during the late Pliocene. Diatom assemblages from lacustrine sediments indicate slightly higher precipitation and humidity than present-day conditions in the Acambay graben. Therefore, climatic forcing may have also contributed to the development of the late Pliocene paleolake in the Acambay graben. Pliocene-Pleistocene volcanic rocks in this part of the Acambay graben range from basaltic andesite to rhyolite. The calc-alkaline composition of these volcanic rocks is similar to others in the modern Mexican Volcanic Belt; they have a continental arc affinity, which is consistent with a tectonic setting within the Mexican Volcanic Belt. The major eruptive episode in the Acambay graben occurred during the early Pliocene, although volcanism, represented by small volcanic structures, continued until the late Pleistocene. This observed decline in volcanism in the Acambay graben correlates with a early Pliocene through Quaternary trenchward migration of volcanism in the Mexican Volcanic Belt.
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Reliability and validity of different handheld dynamometry techniques when measuring hip muscle strength and powerRachid, Zuleiha Ines January 2021 (has links)
No description available.
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Genetic Analysis Of Rhoa Signaling During Epithelial Morphogenesis In DrosophilaLeppert, Amanda Fitch 01 January 2004 (has links)
Epithelial morphogenesis is contingent upon cell shape changes. Cell shape changes are the driving force for the metamorphosis of the adult Drosophila leg from the leg imaginal disc precursor. Genetic analysis has identified several Drosophila genes involved in regulating cell shape changes during leg disc morphogenesis. These include members of the RhoA signaling pathway and the product of the Stubble-stubbloid (Sb-sbd) locus, a transmembrane serine protease. Mutations in the Sb-sbd gene interact genetically with the members of the RhoA signaling pathway, however the nature of the relationship between Sb-sbd serine protease activity and RhoA signaling is not understood. To identify additional components of the RhoA signaling pathway that may help us to understand the role of the Sb-sbd protease in RhoA signaling the Drosophila genome was systematically scanned for genes that interact with Sb-sbd and RhoA mutations using deletions/deficiencies of specified regions of each chromosome. A total of 201 deficiencies uncovering approximately 84.9-91% of the euchromatic genome and spanning the X, second, and third chromosoms were tested. Of the 201 deficiencies tested, five putative interacting genetic regions and one gene within these deficiencies were identified. The candidate gene Eip78C encodes a nuclear steroid hormone receptor previously identified as having an important role in metamorphosis.
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The Hungarian Self and the Chinese Other in the BRIKarlström, Emma January 2023 (has links)
This study examines the representations of identities of the Hungarian Self and the Chinese Other in the Hungarian official foreign policy discourses surrounding the Belt and Road Initiative (BRI). This research paper uses Lene Hansen’s poststructuralist discourse analysis to examine how Hungary’s Prime Minister Viktor Orbán represents Hungary’s identity in relation to the Chinese one since 2013 when the agreement on the BRI was signed. The study’s analysis reveals that the Hungarian Self and the Chinese Other have shared more similarities than differences since 2013. Historically, the Chinese Other has been considered radically different and threatening communist Other in relation to the democratic Hungarian Self. However, the representations of identities took a pivotal turn in the early 2010s when Hungary started to glorify China rather than despite it. Ever since then, the Chinese Other has been constituted as an equal in relation to the Hungarian Self and the differences between them have therefore not been radical. The analysis disclosed that the Other was most often described in regional terms, i.e. as the ‘’East’’ and as something that the Hungarian Self wanted to be a part of. Historically, Hungary and China have been constituted as temporally inferior in relation to the West, however, the analysis showed that the East has caught up with the West and that it is the East that will be leading in the future. Finally, by elevating the issue to a moral basis, Hungary presents itself as an ethically driven actor who has two main responsibilities; a responsibility to include the Chinese Other in European businesses and projects as well as an explicit international responsibility to defend traditional values and differences that exist between nations.
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Petrology and Geochemistry at the Contact of the Round Lake Batholith in Robillard Township, Northeastern OntarioGood, David J. 04 1900 (has links)
The Round Lake Batholith is a composite granitic intrusion into the Archean metavolcanics of the Abitibi Greenstone Belt, Superior Province. The mafic metavolcanics are mainly high iron tholeiitic basalts of ocean floor origin. The intrusion of the batholith has metamorphosed the metavolcanics to amphibolite grade. Moving towards the contact there is no change in the metavolcanics grain size, but mineralogy changes quickly from the actinolite zone with relict pumpellyite to the hornblende zone. Field evidence as well as thin section and chemical
analyses have shown that the dioritic appearing hybrid rock, near the contact, is a product of the mafic meta volcanics assimilation into the batholith. / Thesis / Bachelor of Science (BSc)
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