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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Quartzitos e metaconglomerados auríferos da Sequência da Serra da Boa Vista, borda leste do Quadrilátero Ferrífero, MG, Brasil / Auriferous quartzites and metaconglomerates of the Sequência da Serra da Boa Vista, east Quadrilátero Ferrífero, MG, Brazil

Gabriel Rossi 20 May 2010 (has links)
As ocorrências estudadas da Sequência da Serra da Boa Vista (SSBV) balizam a borda leste do Quadrilátero Ferrífero nos distritos Santa Rita Durão, Bento Rodrigues e Camargos, da cidade de Mariana até a norte de Catas Altas. Sua geologia e as mineralizações de ouro foram enfocados nessa pesquisa baseada em mapeamento 1:25.000, levantamentos estratigráficos detalhados, estudos mineralógico-petrográficos, litogeoquímicos multielementares e das mineralizações auríferas e de morfologia e microgeoquímica de grãos de ouro e minerais associados via MEV-EDS, visando-se a evolução precambriana e a metalogênese do ouro da SSBV, bem como suas relações com as demais rochas da área, principalmente dos supergrupos Minas e Espinhaço. A área compreende um embasamento arqueano granito-gnáissico TTG em contato milonítico com rochas supracrustais do Greenstone Belt Rio das Velhas (Supergrupo Rio das Velhas) e coberturas paleoproterozóicas dos supergrupos Minas e Espinhaço (anteriormente Série Itacolomi) e da SSBV, com coberturas cenozóicas de canga e alúvio-coluvionares. A SSBV é constituída por quartzitos micáceos com estratificações cruzadas acanaladas de pequeno porte a metaconglomerados, caracteristicamente com fuchsita e sulfetos detríticos, com grânulos a calhaus de metachert e, localmente, de itabiritos. Em menor quantidade e mais restritos ocorrem ainda metaconglomerados polimíticos com seixos de quartzitos, metacherts e itabiritos, magnetita-cloritóide quartzitos com estratificações cruzadas acanaladas de pequeno porte com intercalações de grafita e hematita filitos e turmalinitos, assim como metabrechas intraformacionais itabiríticas. Essas rochas apresentam facies xisto verde predominante, a anfibolito, na parte leste da área. A SSBV desenvolveu-se em uma bacia alongada, de direção geral norte-sul, compartimentada, diretamente sobre o embasamento arqueano, com contribuição quartzosa do complexo gnáissico migmatítico TTG e, possivelmente, dos Metagranitóides Borrachudos (arqueanos), e contribuição detrítica do ouro das rochas do Greenstone Belt Rio das Velhas. A compartimentação da bacia levou à sedimentação de facies distintas - ao menos, no início de sua evolução - reforçada por tectônica sinsedimentar ao longo da deposição; nas facies superiores da SSBV predominam amplamente quartzitos micáceos com lentes de metaconglomerados de grânulos de metachert. O ambiente deposicional remete a uma planície de rios entrelaçados, temporariamente alagada e retrabalhada em ambiente intramaré, com inundação marinha final. O estudo das minas Ouro Fino, Cata Preta e Tesoureiro e do garimpo Fazenda Gualaxo mostrou serem as mineralizações de ouro da SSBV singenéticas, de tipo paleoplacer, com remobilização por veios de quartzo internos ao pacote sedimentar (da SSBV), de origens diagenéticas a metamórficas - de tipo paleoplacer modificado. Os grãos de ouro da SSBV apresentam teores de prata variáveis de até 15%, sem paládio, reforçando a proveniência exclusiva do ouro do Greenstone Belt Rio das Velhas. Os resultados obtidos e as observações nas continuações setentrionais da SSBV, incluindo o garimpo do Morro da Água Quente e as minas históricas de Pitanguí, Quebra Osso até Brumado, apontam para um padrão metalogenético único de mineralizações auríferas singenéticas de tipo paleoplaceres e paleoplaceres modificados, descaracterizados em proporções variáveis por retrabalhamentos tectono-metamórficos policíclicos. O potencial aurífero regional da SSBV é confirmado como elevado e para a sua definição são recomendados estudos específicos prospectivos e de viabilidade econômica. / The Sequência da Serra da Boa Vista (SSBV) stratches in a narrow belt of quartzites and metaconglomerates along the eastern border of the Quadrilátero Ferrífero in the districts of Santa Rita Durão, Bento Rodrigues and Camargos from Mariana, Minas Gerais to north of Catas Altas. The geology and gold mineralizations of the SSBV were studied, based on 1:25.000 mapping, detailed stratigraphical cross sections, mineralogical and petrographical studies, lithogeochemistry, geochemistry of the gold mineralizations and morphology and microgeochemistry of gold grains and associated minerals via SEM-EDS in order to understand better the Precambrian evolution and the metallogenesis of the gold of the SSBV as their as its relationships to other rock units of the region, mainly the Minas and Espinhaço supergroups. The study area comprises an Archean basement of TTG granitic gneisses in mylonitic contact with supracrustal rocks of the Rio das Velhas Greenstone Belt (Rio das Velhas Supergroup) and Paleoproterozoic metasedimentary deposits of the Minas and Espinhaço supergroups (formerly, Itacolomi Series) and the SSBV, with Cenozoic canga and alluvial and colluvial covers. Regionally, greenschist facies metamorphism prevails, grading to amphibolite facies in the eastern part of the area. SSBV consists of micaceous quartzites with small-scale cross-bedding and metaconglomerates with granules and pebbles of metachert and, locally, itabirites, characteristically with fuchsite and detritic sulfides. In smaller amounts and more restricted there occur polymictic metaconglomerates (with quartzite, metachert and itabirite pebbles), magnetite-chloritoid quartzites (with small-scale cross-bedding and intercalations of graphite and hematite phyllites and tourmalinite layers), as well as intraformational itabiritic metabrecchias. SSBV deposits developed directly upon the Archean basement in a narrow, elongate basin oriented and subdivided longitudinally in a north-south direction that received quartzose sediments from the gneissic-migmatitic TTG Complex and possibly from the Archean Borrachudos Metagranitoid; detritic gold came from the Rio das Velhas Greenstone Belt. Initial basin subdivision and ensuing synsedimentary tectonics led to sedimentation of different facies. In the upper part of the SSBV micaceous quartzites with lenses of metachert-granule metaconglomerates predominate. The depositional environment in the basin was a coastal braided river plain with periodic marine incursion accompained by intratidal reworkings and, finally, shallow-marine inundation. The study of the Ouro Fino, Cata Preta and Tesoureiro mines and the Garimpo Fazenda Gualaxo showed the gold mineralizations of the SSBV to be syngenetic, of paleoplacer and modified paleoplacer types with diagenetic to metamorphic remobilization (quartz veins) within the sedimentary sequence. Gold grains of the SSBV show variable silver contents up to 15%, without palladium, demonstrating the exclusive provenance of the gold from the Rio das Velhas Greenstone Belt. Results and observations in the northern SSBV, including the Garimpo do Morro da Água Quente and the Pitanguí and Quebra Osso-Brumado historic mines, indicate a homogeneous metallogenetic pattern of syngenetic gold mineralizations of paleoplacer and modified paleoplacer types, obliterated in varying proportions by tectono-metamorphic polyciclic reworkings. This study confirms the high regional gold potential of the SSBV and recommends specific prospective studies and economic viability analyses for its more complete definition.
32

Land reclamation by reindeer lichens : On the complexity of substrate and reindeer grazing on Cladonia spp. dispersal

Godeau, Christine January 2019 (has links)
Reindeer lichens are on a dramatic decline in Sweden, with a 71 % decrease in abundance over the last 60 years. Reindeer (Rangifer tarandus tarandus L.) management, undertaken by indigenous Sámi people, depend upon extensive winter grazing grounds with abundant reindeer lichen cover. The objective of this pilot study is to restore the ecosystem function of reindeer winter grazing in post-industrial environments, by developing an artificial dispersal program of reindeer lichen thalli. This study is performed in co-operation with the mining corp. of LKAB and in consultation with Laevas reindeer herding district. There are two components to this study: I) a comprehensive literature review of indigenous and scientific knowledge regarding reindeer winter grazing and artificial reindeer lichen dispersal; and II) a field assessment of relationships between fructiose lichen occurrence and environmental variables within a coarse grid overlapped on a mosaic of vegetation patches in various successional stages, which cover part of a 28-year old abandoned quartzite heap. My findings validate that a well-drained substrate with a thin humus layer or barren ground together with the occurrence of bryophytes (not Sphagnum spp.) had the highest abundance of fructiose lichens. In contrast, abundant organic soil layer, high soil moisture, and extensive cover of graminoids and herbs showed low abundance of fructiose lichens. I conclude that reindeer lichens are indeed present in a few findings but are still facing environmental and dispersal limitations to become abundant. These limitations can be understood in the light of moisture regimes, instability or compaction of substrate, and limitations within the colonization-pool, and are further discussed with suggested revegetation implementations.
33

Making and understanding embarras bipoints : the replication and operational sequencing of a newly defined stone tool from the eastern slopes of Alberta

Roe, Jason W. 29 June 2009
At pre-ceramic archaeological sites, projectile points are the primary diagnostic tool used by archaeologists. This reliance is even more pronounced along the eastern slopes of Alberta and boreal forest environments of Canada. The acidity of the soils, cryoturbation, and other transformative factors almost always destroy all but the most durable cultural material. In order to obtain the best understanding of precontact lifeways under these conditions we need to recognize and appreciate the diagnostic qualities of all lithic artifacts, not just projectile points. The main goal of my thesis will be to look at one such artifact type. In Alberta, predominantly along the eastern slopes, there have been a number of new and unique artifact types recovered from the cultural resource management studies that have been carried out for several forestry companies, oil and gas operations, and coal industries. The one of particular interest for this thesis will be the Embarras Bipoint (Meyer et al. 2002, Meyer 2003; Roe 2005a, 2005b). <p> I intend to look at the geographical and temporal distribution of Embarras Bipoints. At present, Embarras Bipoints have been assigned to the Early Middle Period (7,500 to 5,000 B.P.). I will compile a data set of other large stone tools to compare to Embarras Bipoints. The theoretical approach will be chaîne opératoire which will be supplemented by the experimental replication of Embarras Bipoints. Ultimately, this technological study of Embarras Bipoints will demonstrate that when found in isolation, in the absence of diagnostic projectile points, or in any un-dateable context have the diagnostic qualities to further our understanding of the Early Middle Period along the Eastern Slopes of Alberta.
34

Making and understanding embarras bipoints : the replication and operational sequencing of a newly defined stone tool from the eastern slopes of Alberta

Roe, Jason W. 29 June 2009 (has links)
At pre-ceramic archaeological sites, projectile points are the primary diagnostic tool used by archaeologists. This reliance is even more pronounced along the eastern slopes of Alberta and boreal forest environments of Canada. The acidity of the soils, cryoturbation, and other transformative factors almost always destroy all but the most durable cultural material. In order to obtain the best understanding of precontact lifeways under these conditions we need to recognize and appreciate the diagnostic qualities of all lithic artifacts, not just projectile points. The main goal of my thesis will be to look at one such artifact type. In Alberta, predominantly along the eastern slopes, there have been a number of new and unique artifact types recovered from the cultural resource management studies that have been carried out for several forestry companies, oil and gas operations, and coal industries. The one of particular interest for this thesis will be the Embarras Bipoint (Meyer et al. 2002, Meyer 2003; Roe 2005a, 2005b). <p> I intend to look at the geographical and temporal distribution of Embarras Bipoints. At present, Embarras Bipoints have been assigned to the Early Middle Period (7,500 to 5,000 B.P.). I will compile a data set of other large stone tools to compare to Embarras Bipoints. The theoretical approach will be chaîne opératoire which will be supplemented by the experimental replication of Embarras Bipoints. Ultimately, this technological study of Embarras Bipoints will demonstrate that when found in isolation, in the absence of diagnostic projectile points, or in any un-dateable context have the diagnostic qualities to further our understanding of the Early Middle Period along the Eastern Slopes of Alberta.
35

Τεκτονική ανάλυση της επαφής μεταξύ Φυλλιτικής-Χαλαζιτικής σειράς και ζώνης Τρίπολης στην περιοχή του Πάρνωνα

Παρασκευουλάκου Μπόκολα, Παναγιώτα 16 May 2014 (has links)
Τεκτονική ανάλυση της επαφής της Φυλλιτικής-Χαλαζιτικής σειράς και των ασβεστόλιθων Τριπόλεως στο ανατολικό περιθώριο του Πάρνωνα. Καθώς όμως και η τεκτονική ανάλυση και η γεωλογική ιστορία της ευρύτερης περιοχής των τεκτονικών παραθύρων, του Πάρνωνα και του Ταΰγετου. / Stractural analysis of the contact of the Phyllite-Quartzite series and the Tripolitsa limestones to the eastern margin of Parnon. As, however, the structural analysis and the geological history of the region of two tectonic windows of Parnon and Taygetos.
36

Ordovician siliceous sediments of the Cordilleran geosyncline

Ketner, Keith Brindley, January 1968 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 120-131).
37

Η γεωμετρία του ελλειψοειδούς της παραμόρφωσης στα μεταμορφωμένα πετρώματα της κεντρικής Κρήτης

Μιχαήλ, Ερασμία 03 November 2011 (has links)
Η Φυλλιτική-Χαλαζιτική ενότητα αποτελεί τμήμα των Εξωτερικών Ελληνίδων και έχει υποστεί μεταμόρφωση σε συνθήκες υψηλής πίεσης. Στην Κεντρική Κρήτη εμφανίζεται κυρίως στο βόρειο τμήμα του παραθύρου των Ταλαίων ορέων. Σκοπός της διπλωματικής εργασίας είναι να προσδιοριστεί η γεωμετρία του τριαξονικού ελλειψοειδούς της παραμόρφωσης και το ποσό της παραμόρφωσης στη Φυλλιτική-Χαλαζιτική ενότητα. Για το σκοπό αυτό συλλέχθηκαν 18 προσανατολισμένα δείγματα χαλαζιακής σύστασης και μετρήθηκαν ελλειπτικοί δείκτες της παραμόρφωσης σε δύο κάθετες μεταξύ τους τομές από κάθε δείγμα. Τα στοιχεία φανερώνουν ότι κατά την πλαστική φάση παραμόρφωσης D1 τα πετρώματα της Φυλλιτικής-Χαλαζιτικής ενότητας παραμορφώθηκαν κυρίως σε συνθήκες πλάτυνσης και σε μικρότερο βαθμό σε συνθήκες επίπεδης παραμόρφωσης. Επιπρόσθετα το ποσό της παραμόρφωσης έχει μια συστηματική και μη γραμμική αύξηση σε σχέση με την απόσταση από την επώθηση βάσης, ενώ ο τύπος του τριαξονικού ελλειψοειδούς δε συνδέεται με τη δομική θέση των δειγμάτων. / The Phyllite-Quartzite (PQ) unit is a part of the External Hellenides and has been subjected to a high pressure metamorphism. In Central Crete PQ unit mainly appears in the northern part of the Talaia window. The aim of this study is to determine the strain ellipsoid geometry and the intensity of deformation in the PQ unit. To do so 18 quartz-rich samples were collected, in which elliptical strain indicators were measured in two mutually perpendicular cross sections. Measurements show that during the D1 phase of the ductile deformation, rocks of the PQ unit were deformed mainly by flattening and secondary by plane strain conditions. Additionally, the amount of deformation shows systematic and non-linear increase relative to the distance of the Basal thrust while the type of strain ellipsoid is not related to the structural position of the samples in the PQ.
38

Estudo da viabilidade da incorporação de resíduo de quartzito na massa de cerâmica vermelha.

CARREIRO, Marcos Emmanuel Araujo. 10 July 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-10T11:43:11Z No. of bitstreams: 1 MARCOS EMMANUEL ARAÚJO CARREIRO - DISSERTAÇÃO (PPGCEMat) 2016.pdf: 2156751 bytes, checksum: b7ae1d2ec31c68bded1c420c6159c28a (MD5) / Made available in DSpace on 2018-07-10T11:43:11Z (GMT). No. of bitstreams: 1 MARCOS EMMANUEL ARAÚJO CARREIRO - DISSERTAÇÃO (PPGCEMat) 2016.pdf: 2156751 bytes, checksum: b7ae1d2ec31c68bded1c420c6159c28a (MD5) Previous issue date: 2016-02-17 / Capes / Nos últimos anos vem aumentando a preocupação com os impactos ambientais gerados pelos resíduos, principalmente os provenientes do beneficiamento de rochas ornamentais. Estes resíduos podem apresentar conteúdos apreciáveis de óxido de silício (SiO2), óxido de alumínio (Al2O3), óxido de cálcio (CaO) e óxidos alcalinos (K2O e Na2O). Além disso, podem conter quantidades significativas de óxido de ferro (Fe2O3). Do ponto de vista mineralógico, dependendo do tipo de rocha ornamental, podem ser constituídos de quartzo, feldspato, mica e calcita. Tais características tornam os resíduos de rochas ornamentais atrativos como uma matéria-prima alternativa para fabricação de materiais da cerâmica tradicional, enfatizando também os aspectos relacionados à questão ambiental, preservação de recursos minerais não renováveis e do meio ambiente. Dentro deste contexto, este trabalho teve como objetivo estudar a viabilidade da incorporação do resíduo de quartzito em uma massa empregada na fabricação de produtos da cerâmica vermelha. As matérias-primas foram submetidas às análises química, granulométrica, térmica, mineralógica e determinação da plasticidade. Foi feito também a classificação do resíduo. Foram formuladas massas com 5, 10, 15 e 20% em peso de resíduo de quartzito, posteriormente conformadas, por meio do processo de prensagem, e queimadas a 800, 900 e 1000ºC. Após queima dos corpos de prova, foram determinadas as propriedades físico-mecânicas: absorção de água, retração linear, porosidade aparente, massa específica aparente e resistência à flexão. Foi avaliada também a cor e fases mineralógicas formadas, além de análise da superfície de fratura por meio de microscopia eletrônica de varredura. O resíduo e as massas foram analisados quanto às características de toxidade. Os resultados evidenciaram que, para a massa estudada, pode ser adicionado até 20% do resíduo de quartzito. / In recent years has been increasing concern about the environmental impacts caused by waste, mainly from the ornamental stone processing. These residues may have appreciable content of silicon oxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), and alkali oxides (Na2O and K2O). Furthermore, it may contain significant amounts of iron oxide (Fe2O3). From the mineralogical standpoint, depending on the type of ornamental rock, may be constituted of quartz, feldspar, mica and calcite. These characteristics make the waste attractive natural stone as an alternative raw material for the production of traditional ceramic materials, also emphasizing the aspects related to environmental issues, preservation of nonrenewable mineral resources and the environment. Within this context, this work aimed to study the feasibility of incorporating quartzite residue in a mass employed in the manufacture of red ceramic products. The raw materials were subjected to chemical analysis, particle size, thermal, mineralogical and determination of plasticity. It was also made the classification of waste. Masses were formulated with 5, 10, 15 and 20% by weight of quartzite residue subsequently shaped by means of pressing process, and fired at 800, 900 and 1000 ° C. After burning of the specimens were determined the physical and mechanical properties: water absorption, linear shrinkage, apparent porosity, bulk density and bending strength. Also it evaluated the color and formed mineralogical phases, and fracture surface analysis using scanning electron microscopy. The residue and the masses were analyzed for toxicity characteristics. The results showed that, for the studied mass, can be added up to 20% of quartzite residue.
39

Incorporação de resíduo de quartzito em massas cerâmicas para uso em louça sanitária.

MEDEIROS, Paula Simone Soares de. 10 July 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-10T13:17:45Z No. of bitstreams: 1 PAULA SIMONE SOARES DE MEDEIROS - DISSERTAÇÃO (PPGCEMat) 2015.pdf: 2261838 bytes, checksum: 5b33d306d5194e626b13402878abf44d (MD5) / Made available in DSpace on 2018-07-10T13:17:45Z (GMT). No. of bitstreams: 1 PAULA SIMONE SOARES DE MEDEIROS - DISSERTAÇÃO (PPGCEMat) 2015.pdf: 2261838 bytes, checksum: 5b33d306d5194e626b13402878abf44d (MD5) Previous issue date: 2015-02-12 / Capes / As indústrias de beneficiamento e transformação de minérios geram quantidades bastante significativas de resíduos e atualmente existe uma preocupação mundial com a contaminação do meio ambiente. Os custos de disposição de resíduos e tratamentos de efluentes de forma ambientalmente correta são elevados, o que tem motivado muitas pesquisas sobre reciclagem desses resíduos para uso como matérias primas cerâmicas. Dentro desse contexto, este trabalho tem como objetivo avaliar a incorporação do resíduo do beneficiamento de quartzito para uso como matérias prima cerâmicas em substituição parcial aos materiais não-plásticos (quartzo e feldspato), para produção de louças sanitárias. Inicialmente as matérias primas convencionais e alternativas (resíduo de quartzito) foram submetidas a uma caracterização físico-mineralógica através das seguintes técnicas: análise granulométrica por difração a laser (AG), difração de raios X (DRX), fluorescência de raios X (EDX), análises térmicas (DTA, TG). Após caracterização foram formuladas barbotinas sem e com resíduo nos percentuais de 2, 4 e 6%, e posteriormente avaliadas suas propriedades reológicas. Após preparação da massa foram conformados corpos de prova pelo processo de colagem, em seguida submetidos a etapa de queima a temperatura de 1.200ºC em forno contínuo e forno intermitente. Após queima foram determinadas as propriedades físicomecânicas: absorção de água; porosidade aparente; perda ao fogo, ensaio mecânico de flexão em três pontos e retração linear. Os resultados evidenciaram que o resíduo de quartzito poderá ser utilizado em até 6% em massa cerâmica para produção em louça sanitária, sendo que os melhores resultados foram para os corpos cerâmicos sinterizados em forno contínuo. / The beneficiation and mineral processing industries generate significant quantities of waste and there is a global concern with environmental contamination. The waste disposal cost and treatments are high, which has motivated much research on recycling of this waste for use as ceramic raw materials. In this context, this work aims to evaluate the incorporation of quartzite processing of waste for use as raw material ceramics in partial substitution of non-plastic materials (quartz and feldspar) for the production of sanitary wares. Initially materials conventional and alternatives (quartzite residue) were subjected to physical and mineralogical characterization using the following techniques: particle size analysis by laser diffraction, X ray diffraction, X ray fluorescence, thermal analysis. After characterizations, the slurries were formulated with and without residue in percentage of 2, 4 and 6%, and then their rheological properties were evaluated. After conformation, test specimens were firing at temperature of 1200 °C in continuous and intermittent furnace. After firing were determined physical and mechanical properties: water absorption; porosity; loss on ignition, mechanical testing of three point bending and linear shrinkage. The results showed that the residue of quartzite can be used by up to 6% ceramic mass production in sanitary ware, and the best results were for the sintered ceramic bodies in continuous furnace.
40

Oroclines of the Iberian Variscan belt: Tectonic and paleogeographic implications

Shaw, Jessica 24 August 2015 (has links)
The Western European Variscan orogenic belt is thought to represent the final in a series of Paleozoic continental collisions that culminated with the amalgamation of the supercontinent Pangea. The Iberian segment of the Variscan belt is characterized by Cantabrian orocline, which is 180º and convex toward the west. Several lines of evidence are at odds with classical interpretation of the Cantabrian orocline as the core of the much larger ‘Ibero-Armorican’ arc, suggesting instead that it is structurally continuous with a second more southerly and complimentary orocline. Paleocurrent data collected from the Lower Ordovician Armorican Quartzite of the deformed Iberian Paleozoic passive margin sequence confirm the existence of the so-called Central Iberian orocline. Structural continuity between the Cantabrian and Central Iberian oroclines suggests that they formed contemporaneously and in the same fashion. Mesoscale vertical-axis folds deforming slaty cleavage and shear fabric within the Ediacaran Narcea Slates have a dominant vergence toward the hinge of the Cantabrian orocline, suggesting that its formation was in part accommodated by a mechanism of flexural shear during buckling of a linear belt in response to an orogen parallel principle compressive stress. The Cantabrian-Central Iberian coupled oroclines therefore palinspastically restore to an originally linear belt 2300 km in length. Provenance analysis of detrital zircons sampled from the Armorican Quartzite along a 1500-km-long segment of the palinplastically restored Iberian passive margin indicate that it originated in a paleogeographic position stretching east-west along the northern limits of north African Gondwana, from the Arabian-Nubian Shield to the Saharan hinterland. Paleomagnetic data and the distribution of Variscan ophiolites support a model of mid-Paleozoic separation of the Variscan autochthon (Armorican continental ribbon) from north Gondwana preceding or in conjunction with a 90º rotation required to reorient the ribbon to a Late Carboniferous north-south trend. Formation of the Iberian coupled oroclines accommodated 1100 km of orogen parallel shortening. The Western European Variscan belt, North American Cordillera, and Eastern European Alpine system are orogens similarly characterized by both coupled oroclines and paleomagnetic inclinations that are significantly shallower than cratonic reference values. Palinspastic restoration of the Alaskan and Carpathian–Balkan coupled oroclines fully resolves inclination anomalies within the Cordillera and Eastern Alpine system, respectively. Inclination anomalies within the Iberian Variscan belt are only partially resolved through palinspastic restoration of the Iberian coupled oroclines, but the sinuous geometry of the belt is not yet fully deciphered. Oroclines within the Western European Variscan belt, not the orogen itself, provide the true record of Pangean amalgamation. / Graduate

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