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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.
41

The effects of climate change on Paleoindian demography

Mullen, Patrick Orion. January 2008 (has links)
Thesis (M.A.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 9, 2009). Includes bibliographical references (p. 44-55).
42

Paleo-arqueologia na formação continuada de professores no Cariri paraibano: por uma educação ambiental Contextualizada para o semiárido

Albuquerque, Márcio Luiz Freire de 07 March 2017 (has links)
Submitted by Maike Costa (maiksebas@gmail.com) on 2017-07-03T14:32:28Z No. of bitstreams: 1 arquivototal.pdf: 10678097 bytes, checksum: 29543a1850ee234cdcfbd9b4c943ff6f (MD5) / Made available in DSpace on 2017-07-03T14:32:28Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 10678097 bytes, checksum: 29543a1850ee234cdcfbd9b4c943ff6f (MD5) Previous issue date: 2017-03-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Paleo-Archaeology and Environmental Education have extensive social roles to fulfill, being both important for understanding natural and human issues. Their use together should be of great interest from educators and the community at large. It can be said that the occurrence of learning about conservation of the environment requires knowledge about the Earth and human history, so for this to be accomplished, we resort to Paleo-Archaeology. This can be verified in researches using interdisciplinary approach, through play, didactics, linked to Environment Education, or was a process of continuing education. Based on this, this study aimed to unveiling processes of continuing teacher education in the perspective of a contextualized Environmental Education for the semiarid region of Paraiba, putting emphasizing in Paleo- Archeology as a form of environmental awareness. This study had a qualitative approach, and used as method the Collaborative Research and elements of the Theory of Bioregionalism, with the development of activities conducted between February 2014 and January 2016 with teachers of the Elementary and High School of the municipality of São João do Cariri, Paraíba. The data were obtained through questionnaires applied to the faculty (pre-test and post-test), to evaluate their opinions about work conditions, their profiles, and their perceptions/conceptions about continuing education, Paleo-Archeology, Environmental Education and related topics, through reports of the activities carried out by the teachers with their students, and through accompanying records. Also were held ludic pedagogical experiential activities with the teachers. In order to analyze practically all the data obtained during this research, the Content Analysis was also used. The information obtained with the pre-test showed that many teachers did not have in-depth knowledge on current educational, environmental and paleoarchaeological issues. At times, they have shown misconceptions about these topics, but they already had a good ability to share their knowledge with their students, not implying that this was occurring in a completely correct manner. With the accomplishment of the experiential activities and the data obtained during and after them, it was observed that the accomplishment of this continuing formation was valid, because there was an increase of knowledge of the teachers regarding the subjects treated during the formation, and occurred substantially positive changes in the way that teachers treat and use Paleo-Archeology to carry out Environmental Education in conjunction with their students, demonstrating that they can be used together for the continuing formation of teachers and for the development of awareness-raising environmental activities. It is expected that the changes that occurred throughout this study are perennial, both in the classroom and in the daily life, and that the information assimilated by them continue to be passed on to their students. Therefore, continuing education is necessary to incorporate diverse and differentiated environmental issues in a contextualized way in the daily lives of teachers, providing new insight in the relations between human beings, society and nature, thereby promoting a reassessment of values and attitudes on coexistence collective and individual, reinforcing the need to be and act as citizens in seeking solutions to environmental problems. / Paleo-Arqueologia e Educação Ambiental (EA) têm amplos papeis sociais a cumprir, sendo importantes para a compreensão de questões naturais e humanas. A utilização destas em conjunto deveria ser de sumo interesse por parte dos educadores e da comunidade em geral. Pode ser dito que a ocorrência de aprendizado sobre a conservação do Meio Ambiente necessita de conhecimento sobre as histórias da Terra e humana, sendo assim, para que isto seja realizado, recorre-se à Paleo-Arqueologia. Isso pode ser verificado em pesquisas que utilizaram-na interdisciplinarmente, de forma lúdica, didática, ligadas a EA, ou como um processo de formação continuada. Baseando-se nisso, esse estudo teve como objetivo principal desvelar processos de formação continuada de professores na perspectiva de uma EA contextualizada para o Semiárido paraibano enfatizando a Paleo-Arqueologia como forma de sensibilização ambiental. Esse estudo teve cunho Qualitativo, e utilizou Pesquisa Colaborativa como método e elementos da Teoria do Biorregionalismo, com o desenvolvimento de atividades realizadas entre fevereiro de 2014 e fevereiro de 2016, com professores dos Ensinos Fundamental e Médio do município de São João do Cariri, Paraíba. Os dados foram obtidos por meio de questionários aplicados ao corpo docente (pré-teste e pós-teste), para serem avaliadas suas opiniões sobre as condições de trabalho, seus perfis, e suas percepções/concepções sobre formação continuada, Paleo-Arqueologia, EA e temas afins, de relatórios das atividades realizadas pelos professores com seus alunos, e de fichas de acompanhamento. Também foram realizadas atividades vivenciais lúdico pedagógicas com os professores. Para se analisar praticamente todos os dados obtidos durante essa pesquisa utilizou-se a técnica da Análise de Conteúdo. As informações obtidas com o pré-teste demonstraram que muitos professores não possuíam conhecimentos aprofundados em questões educacionais atuais, ambientais e paleo-arqueológicas. Em alguns momentos, eles demonstraram ter opiniões equivocadas sobre esses temas, mas já possuíam boa capacidade de compartilhar os seus conhecimentos com seus alunos, não significando que isso estivesse ocorrendo de maneira totalmente correta. Com a realização das atividades vivenciais e os dados obtidos durante as mesmas, e após elas, se observou que a realização desta formação continuada foi válido, pois houve um aumento de conhecimento dos professores quanto aos temas tratados durante ela, e ocorreram mudanças substancialmente positivas na forma como os professores passaram a tratar e utilizar Paleo-Arqueologia para realizar EA em conjunto com seus alunos, demonstrando que elas podem ser empregadas em conjunto para que ocorra a formação continuada de docentes e para o desenvolvimento de atividades de sensibilização ambiental. Se espera que as mudanças que ocorreram ao longo desse estudo sejam perenes, tanto em sala de aula quanto no cotidiano, e que as informações assimiladas por eles continuem a ser repassadas a seus alunos. Sendo assim, a formação continuada é necessária para incorporar questões ambientais diversas e diferenciadas de forma contextualizada no cotidiano dos professores, propiciando uma nova percepção nas relações entre o ser humano, sociedade e natureza, promovendo assim, uma reavaliação de valores e atitudes na convivência coletiva e individual, reforçando a necessidade de ser e agir como cidadãos na busca de soluções para problemas ambientais.
43

Geocronologia e evolução tectônica paleo-mesoproterozoica do oriente boliviano - região sudoeste do craton amazônico / Paleo-mesoproterozoic Tectonic Evolution and Geocronology of Eastern Bolivia, SW Amazonian Craton

Salinas, Gerardo Ramiro Matos 03 November 2010 (has links)
Este trabalho caracteriza a evolucao tectónica, identificando a cronologia dos principais eventos tectono-magmáticos do Pré-Cambriano Boliviano. A complexa evolucao geológica do Oriente da Bolívia se estende desde o Paleo a Mesoproterozoico compreendendo as provincias Rio Negro Juruena, Rondoniana San Ignacio e Sunsás na regiao conhecida como Bloco Paragua. Diversos métodos de estudo foram adotados na pesquisa tendo em vista tratar-se de um terreno com evolução policíclica e incluiram, alem do mapeamento geológico e petrografía dos principais tipos de rocha, a metodologia U-Pb para determinação da idade de corpos graníticos e a metodologia Sm-Nd na estimativa de idade das fontes destes corpos plutônicos e inferências de ordem petrogenética, bem como dados geoquímicos obtidos para detalhamento das interpretações petrogenéticas. Nas interpretações houve ainda a avaliação critica da literatura recente, a integração de dados de campo, aeromagnéticos e aero-radiométricos, inclusive embasadas na experiência profissional do autor. Os dados obtidos na última década modificaram substancialmente a concepcao do Pré-Cambriano Boliviano, tendo sido caracterizados tres conjuntos litológicos temporalmente distintos antecedendo a orogenia San Ignacio. O granito Correreca na parte meridional da area possui idade 207Pb-206Pb de 1,92 1,89 Ga, com modelo de idades TDM de 2,8 a 2,9 Ga e valores de Nd(t) de -8,5 e -9,4. A Suite Yarituses composta pelos granitos La Cruz, Refugio e San Pablo possui quimismo calcio-alcalino. Os dados U-Pb SHRIMP, TIMS e abrasão por laser-ICPMS indicam a formação desta suíte no lapso temporal entre 1673 a 1621 Ma. A idade de cristalização U-Pb SHRIMP do granito La Cruz é de 1673 ± 21 Ma, idade modelo TDM de 1,83 Ga e valor de Nd(t) de + 2.1 indicativo de derivação mantélica. O granito Refugio tem idade U-Pb TIMS de 1673 ± 25 Ma e o pluton San Pablo idade ICPMS por laser ablasion de 1621 ± 80 Ma (idade TDM de 1,7 Ga e valor de Nd(t) de + 3,5). Este conjunto de dados sugere uma derivação mantelica principal para a suite Yarituses. O granodiorito San Ramón possui uma idade de cristalização de 1429 ± 4 Ma (SHRIMP), TDM de 1,7 Ga, e Hf(t) entre + 3,49 e +5,47 e representa um evento de geração da crosta, a partir de material juvenil. O magmatismo, deformação e metamorfismo da orogênese San Ignácio constitui o principal evento representado na área de estudo, cujo maior representante é o Complexo Granitoide Pensamiento com seus plutons sin a tardi-cinemáticos e tardi a pos-cinemáticos. Os granitos San Martín, La Junta e Diamantina possuem idades de cristalizacao de 1373- 1340 Ma, idades modelo TDM de 1,6 a 2,0 Ga, com valores de Nd(t) de + 2.0 ate -4,0. Os granitos Las Maras, Talcoso, Limonal e San Andrés produziram idades de cristalização de 1347 a 1275 Ma. As idades TDM dos granitos Limonal e San Andrés correspondem a 1,9 e 1,8 e Nd(t) de -1,4 e 1,6 respectivamente. A geoquímica em rocha total indica uma composição compatível com arco magmático, corroborando a assinatura acima dos parâmetros petrogeneticos. Em suma, a orogênese San Ignácio representa um arco acrescionário de natureza continental que construiu a arquitetura final da província Rondoniana-San Ignacio pela colisão entre o Bloco Paraguá e a província Rio Negro-Juruena. A evolução mesoproterozoica finaliza com a formação da faixa colisional Sunsás. Esta orogênese produziu plutonismo sin a tardi cinematico e tardi a cinemático marcando o limite com o bloco Paragua. A natureza alóctone e colisional do orogeno Sunsás como o evento mais jovem do Cráton Amazônico é marcada por frentes tectônicos, bem definidos de sentido sinistral, convergentes para o Bloco Paragua. / This work characterizes the tectonic and magmatic evolution of the Precambrian shield of Bolivia. The complex geological evolution of the eastern Bolivia extends from the Paleo- to Mesoproterozoic, and can be related with the magmatic and metamorphic events that are ascribed to the Rio Negro - Juruena (1.78-1.60 Ga), Rondonian - San Ignacio (1.56-1.30 Ga) and Sunsás Aguapei (1.25-1.00 Ga) provinces, known in Bolivia as the Paragua block. Several methods of study were adopted in the research with the scope that this is a land with polycyclic evolution. As such our study included, besides the geological mapping and petrography of major rock types, the U-Pb age determinations of granitoid rocks, Sm-Nd and Rb-Sr isotopic analyses, as well as geochemical data. At the interpretation there was the critical evaluation of recent papers, the integration of field data, aeromagnetic and aero-radiometric, including the field experience of the author. The data obtained in the last decade have substantially changed the geology of the Bolivian Precambrian shield. It has been characterized three temporally distinct granite suites preceding the San Ignacio orogeny (1.37-1.30 Ga): the Correreca granite in the southern part of the area has 207Pb/206Pb age from 1.92 to 1.89 Ga, with TDM model ages of 2.8 to 2.9 Ga and values of Nd(t) of -8.5 and -9.4; the Yarituses suite (La Cruz, Refugio and San Pablo granites) shows calc-alkaline signature. Data U-Pb SHRIMP, TIMS and ICPMS laser ablation indicate the formation of this suite between 1673 to 1621 Ma. The U-Pb SHRIMP crystallization age of La Cruz granite is 1673 ± 21 Ma, TDM model age of 1.83 Ga and Nd(t) of +2.1 indicative of a predominantly mantle source. The Refugio granite has U-Pb TIMS age of 1673 ± 25 Ma and the San Pablo pluton yields a ICPMS Laser ablation age of 1621 ± 80 Ma (TDM age of 1.7 Ga and Nd(t) +3.5). These data suggest again a mantle source for the Yarituses suite. The San Ramon granodiorite event has a crystallization age of 1429 ± 4 Ma (SHRIMP), TDM of 1.7 Ga, and Hf(t) between +3.49 and +5.47 and represents a juvenile accreted episode. The magmatism, deformation and metamorphism of San Ignacio orogeny is the main event of the study area, represented by the Pensamiento Granitoid Complex with sin to late-kinematic and late to post-kinematic plutons. The San Martín, La Junta and Diamantina granites have crystallization ages of 1373 - 1340 Ma, TDM model ages from 1.6 to 2.0 Ga, with values of Nd(t) from 2.0 up to -4.0. The Las Maras, Talcoso, Limonal and San Andrés granites yielded crystallization ages of 1347-1275 Ma. The TDM ages of Limonal and San Andrés granites are between 1.9 and 1.8 Ga and the Nd(t) values of -1.4 and +1.6 respectively. The whole rock geochemistry of these granites indicates a composition consistent with the magmatic arc. Thus the San Ignacio orogeny represents a continental accretionary arc that built the final architecture of the Rondonian-San Ignacio province (1.56-1.30 Ga) by the collision between the Paragua block and the Rio Negro -Juruena province (1.78-1.60 Ga). The Mesoproterozoic evolution of the SW margin of the Amazonian craton ends with the formation of the Sunsás collisional belt that produced sin to-late and late topost- kinematic plutonism. The allochthonous and collisional nature of the Sunsás orogeny is marked by tectonic fronts, with well-defined sinistral sense, converging towards the Paragua block.
44

Evaluation Of A Cenozoic Lacustrine Basin-hancili Formation (kalecik-ankara) And Its Paleoenvironment And Paleoclimate Analysis Based On Mineral Facies

Aker, Serdar 01 January 2013 (has links) (PDF)
The major purpose of this study is to evaluate the paleoenvironmental and paleoclimatological conditions during the Middle Miocene-Early Pliocene in Kalecik-Ankara by using mineralogical and geochemical proxies from Han&ccedil / ili Formation. To achieve a high-resolution paleoclimate data, 2 stratigraphic sectioning and 1 continous core drilling were examined. Field studies were followed by analytical techniques on the selected representative samples. The mineralogical compositions of the bulk samples and the minerals of the clay fractions were determined by X-ray diffractometer. Scanning electron microscopic analyses were also carried on the specific samples which have the potential to define the important microstructural units. The major and trace elemental compositions were determined by X-ray fluoresence spectrometer. Additionally, the stable isotope compositions of the samples selected from the continous core drilling on Han&ccedil / ili formation were among the major proxies to gather a paleoenvironmental and paleoclimatrological approach. All the proxies employed for this study clearly indicate that mineralogical and geochemical signatures are consistent with each other and can be used for paleoclimatic interpretations. The stable isotope values point that C4 plants were dominant during the deposition of Han&ccedil / ili Formation, while evaporation caused the development of alkaline environment which is seasonally dry with depositional temperature approximately between 25-30&deg / C. During deposition, lava flowand tuff were deposited due to the volcanic activity in the vicinity of the lake. Based on this volcanism, economical bentonite deposits were originated. The lake at which the Han&ccedil / ili formation was deposited, completed its development in a time to time silicate rich and salty-alkaline anvironment.
45

Late Pleistocene deglaciation histories in the central Mérida Andes (Venezuela) / Histoires de déglaciation pendant le Pléistocène Supérieur dans les Andes centrales de Mérida (Venezuela)

Angel Ceballos, Isandra Fortuna 12 February 2016 (has links)
Les Andes de Mérida (Venezuela) est caractérisé par la présence de morphologie glaciaire bien préservée entre 2400-4978 m. Les études de ces morphologies glaciares font la contribution pour mieux comprendre et reconstruire la Dernière Glaciation aux Andes Vénézuéliennes. La reconstruction de la Dernière Glaciation (connue dans la région comme Glaciation Mérida) était limitée par la disponibilité de chronologie glaciaire. Cette thèse fait sa contribution à la reconstruction de la Dernière Glaciation et à la connaissance du paléoclimat depuis le Pléistocène Superieur. La méthodologie a involucré l´analyse géomorphologique et l´étude géochronologique. La morphologie glaciaire a été datée avec la technique de nucléides cosmogéniques produits in-situ (10Be). Cette technique est appropriée pour dater les matériels riches en quartz et la période d´intérêt. Les inférences des conditions paleoclimatiques ont été faites sur la base des analyses de la paléo ELA.Des différentes dynamiques glaciares ont été identifiées aux Andes centrales de Mérida. Dans les vallées de Mucubají et Mucuchache, la dynamique a été caractérisée par plusieurs étapes de avancé-arrêt des glaciaires dans un recul général de la glace. Dans les vallées de Gavidia et Mifafí, la disparition des glaciares a été très rapide avec la vitesse de recul plus haute (entre 4-7 km/ky). Divers caractéristiques morpho métriques comme la pente du fond de la vallée, la topographie de la zone d´accumulation (cirques glaciares avec les murs très incliné), des surfaces de la zone d´accumulation et son orientation ont aussi contrôlé les différents dynamiques glaciares.Les avancées des glaciares ont été identifiées entre 2500-4200 m. Les avancées glaciares pendant le MIS 3 ont été reconnues à Sierra Nevada. Ces avancées ont été liées aux hautes précipitations dans le nord de l´Amérique de Sud produites par l´activité de la Zone de Convergence Intertropical. Ces avancées ont été aussi reliées aux conditions plus chaudes et humides dans l´Hémisphère Nord (aussi ces conditions ont été identifiées aux Andes vénézuéliennes et sont connues comme l´Interstadío El Pedregal). Les avancées glaciares pendant le Dernière Maximum Glaciares ont été enregistrées en Sierra Nevada á Mucubají et Las Tapias entre 3100-3600 m. Principalement, les avancées glaciares MIS 2 sont arrivées pendant l´Oldest Dryas-El Caballo Estadío à 17 ka. Ces avancées glaciares ont été reliées aux températures froides dans l´Hémisphère Nord et les températures plus froides enregistrées dans les carottes de glaciares tropicaux.Mots clésDatation par cosmogéniques produits in-situ, morphologie glaciaire, Pléistocène, Dernière Glaciation, LGM, paléo ELA. / The central Mérida Andes (Venezuela) landscape is characterized by the presence of well-preserved glacial landforms located between 2400 and 4978 m a.s.l. Geomorphological studies of these glacial landforms significantly contribute to the Venezuelan Andes glaciations reconstructions. However, Last Glaciation (locally called Mérida Glaciation) was poorly reconstructed because of limited chronological data. This dissertation attempts to contribute to the Last Glaciation reconstruction and paleoclimate knowledge since the late Pleistocene. Accordance this necessity, the methodology involved geomorphological analysis and geochronological study. Glacial landforms were dated based on the Terrestrial Cosmogenic Nuclide dating (10Be). This method is suitable for date quartz-rich materials and for the period of interest. To deduce paleoclimate conditions an analysis based on paleo ELA was developed.In the central Mérida Andes different Late Pleistocene glacier dynamics were identified. In the Mucubají and the Mucuchache valleys, successive stages of glacier stop-advance were identified during an overall glacier withdrawal. In the Gavidia and Mifafí valleys, glacier withdrawal was rapid with the highest retreat rates (between 4-7 km/ky). Morphometric features as glaciers bottom valley slopes, accumulation zone topography (glaciers cirques with steep walls), areas and orientation controlled different glaciers dynamics.Glacier advances were evidenced between 2500-4200 m. MIS 3 glaciers advances has been recognized in the Sierra Nevada. These were related to the highest runoff in the north of South America produced by the Intertropical Convergence Zone (ITCZ) and the local warm and wet climate conditions (locally named El Pedregal Interstadial). LGM glacier advances were recorded in Sierra Nevada in the Mucubají and Las Tapias between 3100-3600 m. MIS 2 Glaciers advances mainly occurred during the Oldest Dryas- El Caballo Stadial at around 17 ka. These glaciers advances correlate to the cold temperatures in the North Hemisphere and the coldest temperatures recorded in tropical ice cores.KeywordsTerrestrial cosmogenic nuclides dating, TCN, cosmogenic dating, glacial landforms, Andes Mérida, Venezuela. Pleistocene, Last Glaciation, LGM, paleo ELA, tropic paleoclimate.
46

Geocronologia e evolução tectônica paleo-mesoproterozoica do oriente boliviano - região sudoeste do craton amazônico / Paleo-mesoproterozoic Tectonic Evolution and Geocronology of Eastern Bolivia, SW Amazonian Craton

Gerardo Ramiro Matos Salinas 03 November 2010 (has links)
Este trabalho caracteriza a evolucao tectónica, identificando a cronologia dos principais eventos tectono-magmáticos do Pré-Cambriano Boliviano. A complexa evolucao geológica do Oriente da Bolívia se estende desde o Paleo a Mesoproterozoico compreendendo as provincias Rio Negro Juruena, Rondoniana San Ignacio e Sunsás na regiao conhecida como Bloco Paragua. Diversos métodos de estudo foram adotados na pesquisa tendo em vista tratar-se de um terreno com evolução policíclica e incluiram, alem do mapeamento geológico e petrografía dos principais tipos de rocha, a metodologia U-Pb para determinação da idade de corpos graníticos e a metodologia Sm-Nd na estimativa de idade das fontes destes corpos plutônicos e inferências de ordem petrogenética, bem como dados geoquímicos obtidos para detalhamento das interpretações petrogenéticas. Nas interpretações houve ainda a avaliação critica da literatura recente, a integração de dados de campo, aeromagnéticos e aero-radiométricos, inclusive embasadas na experiência profissional do autor. Os dados obtidos na última década modificaram substancialmente a concepcao do Pré-Cambriano Boliviano, tendo sido caracterizados tres conjuntos litológicos temporalmente distintos antecedendo a orogenia San Ignacio. O granito Correreca na parte meridional da area possui idade 207Pb-206Pb de 1,92 1,89 Ga, com modelo de idades TDM de 2,8 a 2,9 Ga e valores de Nd(t) de -8,5 e -9,4. A Suite Yarituses composta pelos granitos La Cruz, Refugio e San Pablo possui quimismo calcio-alcalino. Os dados U-Pb SHRIMP, TIMS e abrasão por laser-ICPMS indicam a formação desta suíte no lapso temporal entre 1673 a 1621 Ma. A idade de cristalização U-Pb SHRIMP do granito La Cruz é de 1673 ± 21 Ma, idade modelo TDM de 1,83 Ga e valor de Nd(t) de + 2.1 indicativo de derivação mantélica. O granito Refugio tem idade U-Pb TIMS de 1673 ± 25 Ma e o pluton San Pablo idade ICPMS por laser ablasion de 1621 ± 80 Ma (idade TDM de 1,7 Ga e valor de Nd(t) de + 3,5). Este conjunto de dados sugere uma derivação mantelica principal para a suite Yarituses. O granodiorito San Ramón possui uma idade de cristalização de 1429 ± 4 Ma (SHRIMP), TDM de 1,7 Ga, e Hf(t) entre + 3,49 e +5,47 e representa um evento de geração da crosta, a partir de material juvenil. O magmatismo, deformação e metamorfismo da orogênese San Ignácio constitui o principal evento representado na área de estudo, cujo maior representante é o Complexo Granitoide Pensamiento com seus plutons sin a tardi-cinemáticos e tardi a pos-cinemáticos. Os granitos San Martín, La Junta e Diamantina possuem idades de cristalizacao de 1373- 1340 Ma, idades modelo TDM de 1,6 a 2,0 Ga, com valores de Nd(t) de + 2.0 ate -4,0. Os granitos Las Maras, Talcoso, Limonal e San Andrés produziram idades de cristalização de 1347 a 1275 Ma. As idades TDM dos granitos Limonal e San Andrés correspondem a 1,9 e 1,8 e Nd(t) de -1,4 e 1,6 respectivamente. A geoquímica em rocha total indica uma composição compatível com arco magmático, corroborando a assinatura acima dos parâmetros petrogeneticos. Em suma, a orogênese San Ignácio representa um arco acrescionário de natureza continental que construiu a arquitetura final da província Rondoniana-San Ignacio pela colisão entre o Bloco Paraguá e a província Rio Negro-Juruena. A evolução mesoproterozoica finaliza com a formação da faixa colisional Sunsás. Esta orogênese produziu plutonismo sin a tardi cinematico e tardi a cinemático marcando o limite com o bloco Paragua. A natureza alóctone e colisional do orogeno Sunsás como o evento mais jovem do Cráton Amazônico é marcada por frentes tectônicos, bem definidos de sentido sinistral, convergentes para o Bloco Paragua. / This work characterizes the tectonic and magmatic evolution of the Precambrian shield of Bolivia. The complex geological evolution of the eastern Bolivia extends from the Paleo- to Mesoproterozoic, and can be related with the magmatic and metamorphic events that are ascribed to the Rio Negro - Juruena (1.78-1.60 Ga), Rondonian - San Ignacio (1.56-1.30 Ga) and Sunsás Aguapei (1.25-1.00 Ga) provinces, known in Bolivia as the Paragua block. Several methods of study were adopted in the research with the scope that this is a land with polycyclic evolution. As such our study included, besides the geological mapping and petrography of major rock types, the U-Pb age determinations of granitoid rocks, Sm-Nd and Rb-Sr isotopic analyses, as well as geochemical data. At the interpretation there was the critical evaluation of recent papers, the integration of field data, aeromagnetic and aero-radiometric, including the field experience of the author. The data obtained in the last decade have substantially changed the geology of the Bolivian Precambrian shield. It has been characterized three temporally distinct granite suites preceding the San Ignacio orogeny (1.37-1.30 Ga): the Correreca granite in the southern part of the area has 207Pb/206Pb age from 1.92 to 1.89 Ga, with TDM model ages of 2.8 to 2.9 Ga and values of Nd(t) of -8.5 and -9.4; the Yarituses suite (La Cruz, Refugio and San Pablo granites) shows calc-alkaline signature. Data U-Pb SHRIMP, TIMS and ICPMS laser ablation indicate the formation of this suite between 1673 to 1621 Ma. The U-Pb SHRIMP crystallization age of La Cruz granite is 1673 ± 21 Ma, TDM model age of 1.83 Ga and Nd(t) of +2.1 indicative of a predominantly mantle source. The Refugio granite has U-Pb TIMS age of 1673 ± 25 Ma and the San Pablo pluton yields a ICPMS Laser ablation age of 1621 ± 80 Ma (TDM age of 1.7 Ga and Nd(t) +3.5). These data suggest again a mantle source for the Yarituses suite. The San Ramon granodiorite event has a crystallization age of 1429 ± 4 Ma (SHRIMP), TDM of 1.7 Ga, and Hf(t) between +3.49 and +5.47 and represents a juvenile accreted episode. The magmatism, deformation and metamorphism of San Ignacio orogeny is the main event of the study area, represented by the Pensamiento Granitoid Complex with sin to late-kinematic and late to post-kinematic plutons. The San Martín, La Junta and Diamantina granites have crystallization ages of 1373 - 1340 Ma, TDM model ages from 1.6 to 2.0 Ga, with values of Nd(t) from 2.0 up to -4.0. The Las Maras, Talcoso, Limonal and San Andrés granites yielded crystallization ages of 1347-1275 Ma. The TDM ages of Limonal and San Andrés granites are between 1.9 and 1.8 Ga and the Nd(t) values of -1.4 and +1.6 respectively. The whole rock geochemistry of these granites indicates a composition consistent with the magmatic arc. Thus the San Ignacio orogeny represents a continental accretionary arc that built the final architecture of the Rondonian-San Ignacio province (1.56-1.30 Ga) by the collision between the Paragua block and the Rio Negro -Juruena province (1.78-1.60 Ga). The Mesoproterozoic evolution of the SW margin of the Amazonian craton ends with the formation of the Sunsás collisional belt that produced sin to-late and late topost- kinematic plutonism. The allochthonous and collisional nature of the Sunsás orogeny is marked by tectonic fronts, with well-defined sinistral sense, converging towards the Paragua block.
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Successeurs des dinosaures ? Paléobiologie et paléoécologie d’un oiseau géant terrestre du Paléogène / -

Angst, Delphine 17 November 2014 (has links)
Les Gastornithidae sont des oiseaux géants terrestres présents dans le Tertiaire (Paléocène- Eocène) d'Europe, d'Amérique du Nord et d'Asie. Bien que ces oiseaux soient connus depuis le 19ème siècle, leur écologie et les environnements dans lesquels ils vivaient sont encore très mal connus. Cette thèse propose donc d'apporter des réponses sur ces deux points afin de mieux comprendre ces oiseaux grâce à une approche pluridisciplinaire, combinant des études de morphologie-fonctionnelle, de géochimie isotopique, et de paléontologie. Nous avons pu déterminer que cet oiseau de deux mètres de haut devait peser entre 110 et 260 kg, et avait un déplacement relativement lent ne lui permettant pas de courir rapidement et longtemps. Le régime alimentaire des Gastornithidae, en débat depuis plus de vingt ans, a été ré-étudié grâce à une étude de géochimie isotopique combinée à une étude de morphologie fonctionnelle, permettant de conclure à une alimentation herbivore. Parallèlement, les paléo-environnements dans lesquels évoluaient cet oiseau ont également pu être étudiés grâce une étude de géochimie isotopique appliquée à des coquilles d'oeufs fossiles du Sud de la France attribuées à Gastornis dans cette thèse. Ces grands oiseaux vivaient donc dans un environnement relativement sec et chaud avec probablement une alternance de saison sèche et humide pour le Sud de la France, ce qui est différent de ce qu'on connait pour des environnements du centre de l'Allemagne où d'autres fossiles de Gastornis ont été trouvés, et où la végétation montre un environnement plus humide. Cela montre donc que cet oiseau avait une bonne capacité d'adaptation à différents environnements, ce qui lui a probablement permis de franchir le PETM sans être particulièrement affecté, comme le montre le registre fossile dans lequel aucune extinction, aucune variation géographique ou anatomique ne sont observées dans cette famille contrairement au cas de nombreux mammifères / Gastornithidae are a familly of large ground fossils birds present in the Tertiary (Paleocene- Eocene) from Europe, North America and Asia. Although these birds are known since the beginning of the 19th century, their ecology and the environment where they lived are still poorly known. Therefore, this PhD propose to bring some answers about this two points in order to better understand these birds using a multidisciplinary approach, including functional morphology, isotope geochemistry and paleontological studies. We have determined that this two meter high bird should weigh around 110 to 260 kg, and had a relatively slow locomotion not allowing him to run quickly and for a long time. The diet of the Gastornithidae, discussed since more twenty years, has been studied using an isotopic geochemical approach combine with a morphofunctional study, which permits to conclude to an herbivore diet. In parallel, paleo-environments where lived this bird have also been studied using isotopical analysis applied on fossils bird’s eggshells from the southern France, attributed to Gastornis in this thesis. Thus these large birds lived in an environment relatively dry and hot, with probably an alternance of dry and wet saison in the southern France, which is different than which is known in middle Germany environments where other Gastornis fossils were found, and where vegetation shows an environment wetter. Therefore, that shows that this bird had a good adaptability to different environments, which allowed him to cross the PETM without being particularly affected as shown in the fossil record, on the contrary to numerous mammals
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Evaluating forcings in an ensemble of paleo-climate models

Muri, Helene Østlie January 2009 (has links)
No description available.
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Millennial-scale atmospheric CO2 variations during the Marine Isotope Stage 6 / Variations atmosphériques du CO2 à l'échelle millénaire durant le stade isotopique MIS 6

Shin, Jinhwa 18 March 2019 (has links)
L’objectif principal de cette thèse était de comprendre la variabilité millénaire du CO2 atmosphérique durant le stade isotopique marin 6 (Marine Isotope Stage 6, MIS 6), l’avant dernière période glaciaire (185-135 ka BP). Durant la première partie de la période MIS 6 (185-160 ka BP), 6 oscillations climatiques millénaires peuvent être observées dans des indicateurs de la température antarctique, du phénomène de bascule bipolaire dans la région Atlantique Nord et de l’intensité des moussons des basses latitudes. Un cycle hydrologique intensifié et des vêlages d’iceberg dans l’Atlantique Nord pourraient avoir impacté la circulation atlantique méridionale de retournement (Atlantic Meridional Overturning Circulation, AMOC) durant MIS 6 (Margari et al., 2010). La reconstruction de CO2 atmosphérique à partir des carottes antarctiques peut fournir des informations clés sur le lien entre CO2 atmosphérique et variabilité climatique millénaire. Cependant, les enregistrements existants du CO2 à partir de la carotte de glace de Vostok ne montrent pas de variabilité millénaire du fait de trop mauvaises résolution et précision.Pour examiner comment le CO2 atmosphérique est lié avec le changement climatique sur les échelles de temps millénaires pendant le MIS 6, nous avons analysé 150 échantillons de CO2 atmosphérique obtenus à partir de la carotte EPICA Dome C (EDC) sur la période 189.4-135.4 ka BP. Une oscillation mineure et 5 oscillations majeures du CO2 atmosphérique pendant la première partie de la période du MIS 6 (189-160 ka BP) ont été découvertes. Cette variabilité est très liée avec la température antarctique. Pendant les périodes stadiales courtes dans l’Atlantique Nord, les variations de CO2 atmosphérique sont négligeables et découplées avec la variabilité de la température antarctique. Durant ces périodes, la force de l’upwelling dans l’océan austral pourrait ne par être suffisante pour impacter le CO2 atmosphérique. De plus, 2 modes de variations du CO2 sont présentes pendant la période du MIS 6. Le maximum de dioxyde de carbone 6 (carbon dioxide maxima 6, CDM 6) suit le réchauffement rapide de l’hémisphère Nord de seulement 100±360 ans, alors que les retards pour les CDM 3 et 4 sont bien plus longs, 1 100±280 ans en moyenne. Ces deux modes de variation du CO2 pourraient être liés à un changement de mode de l’AMOC de la première partie du MIS 6 au MIS 6.5. Ces deux phénomènes sont aussi observés pendant la dernière période glaciaire. Cependant, les données disponibles permettent seulement une discussion exploratoire des mécanismes responsables de la variabilité du CO2 pendant MIS 6. Comme les conditions aux limites de la dernière période glaciaire ne peuvent pas être appliquées au MIS 6, des données supplémentaires et des études par modélisation du MIS 6 sont nécessaires. / The main objective of this thesis is to understand the millennial variability of atmospheric CO2 during the Marine Isotope Stage 6 (MIS 6), the penultimate glacial, period (185─135 kyr BP). During the early MIS 6 period (185-160 kyr BP), 6 millennial-scale climate oscillations can be observed in proxy records of Antarctic temperature, the bipolar see-saw phenomenon in the North Atlantic region, and Monsoon intensity in low latitudes. An intensified hydrological cycle and iceberg calving in the North Atlantic may have impacted on the Atlantic Meridional Overturning Circulation during MIS 6 (Margari et al., 2010). Atmospheric CO2 reconstructions from Antarctic ice cores can provide key information on how atmospheric CO2 concentrations are linked to millennial-scale climate changes. However, existing CO2 records from the Vostok ice core do not show the millennial variability due to the lack of suitable temporal resolution and precision. To understand atmospheric CO2 variability during MIS 6, a precision of less than 2 ppm is mandatory, because there is a possibility that we could observe small CO2 variability of less than 5 ppm during the smaller Antarctic isotope maxima events as observed during the last glacial period (Ahn and Brook, 2014; Bereiter et al., 2012).To investigate how atmospheric CO2 is related with climate change on millennial time scales during MIS 6, we reconstructed 150 samples of atmospheric CO2 data from the EPICA Dome C (EDC) ice core during the MIS 6 period (189.4─135.4 kyr BP). One minor and five major variabilities of atmospheric CO2 during the early MIS 6 period (189─160 kyr BP) were found. These variabilities are highly matched with Antarctic temperature. During the short stadials in the North Atlantic, atmospheric CO2 variations are negligible and decoupled with temperature variations in Dome C. During this period, the strength of upwelling in the southern ocean might not be sufficient to impact on atmospheric CO2. In addition, 2 modes of CO2 variations are present in the MIS 6 period. Carbon dioxide maxima (CDM) 6 lags abrupt warming in the Northern Hemisphere by only 100±360 yrs, while the lags for CDM 3 and 4 are much longer, 1,100±280 yrs on average. Theses 2 modes of CO2 variations might be related with a mode change of AMOC from the earliest MIS 6 to MIS 6.5. These two phenomena also are observed during the last glacial period. However, the limited available proxy data permit only an exploratory discussion of the mechanisms responsible for CO2 variability during MIS6. Because the boundary conditions of the last glacial period cannot be applied to MIS 6, additional proxy data and multiple modelling studies conducted during MIS 6 period are needed.
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Evaluation of a modified paleolithic dietary intervention for the treatment of relapsing-remitting multiple sclerosis

Irish, Amanda Kay 01 May 2015 (has links)
Improvements in fatigue and quality of life observed in primary and secondary progressive multiple sclerosis (MS) patients adhering to a modified Paleolithic dietary intervention (MPDI), nutritional supplementation, exercise, and neuromuscular electrical stimulation regime are hypothesized to be due primarily to the effect of diet. However, no research has been conducted evaluating effects of the dietary intervention alone thus, the purpose of this research was to evaluate a MPDI in the treatment of Relapsing-Remitting Multiple Sclerosis (RRMS). We tested effects of the MPDI in seventeen men and women (mean age: 36.3 ±4.7 years) with neurologist-verified RRMS. Nine subjects (one male) were randomized to a "usual care" (control) group and eight subjects (one male) were taught the MPDI. Both groups adhered to their assigned protocol for three months. Significant improvement was seen in Fatigue Severity Scale (FSS, p=0.03), Multiple Sclerosis Quality of Life-54 Physical Health (MSQOL-P, p=0.03), and Mental Health (MSQOL-M, p=0.02) scores from baseline in MPDI subjects compared to controls. Increased vitamin K serum levels (p=0.02) were also observed in MPDI subjects at three months compared to controls. Significantly reduced time to complete 9-Hole Peg Test (9-HPT) with the dominant hand (p=0.02) was also observed. Our results indicate trends for improved non-dominant 9-HPT (p=0.05), Metabolic Equivalent Tasks (METs, p=0.08), and 25-Foot Walk (25-FW, p=0.09) scores from baseline in MPDI subjects compared to controls. A Paleolithic diet may be useful in the treatment and management of MS, by reducing perceived fatigue, increasing mental and physical quality of life, increasing exercise capacity, and improving hand and leg function. The MPDI may also reduce inflammation as evidenced by increased vitamin K serum levels.

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