Les principaux gisements d’uranium connus du Niger (Arlit, Akouta et Imouraren) sont tous localisés dans le bassin de Tim Mersoï, à l’Est de la faille d’Arlit. Les gisements d’Arlit et d’Akouta sont encaissés dans des formations Carbonifères et présentent une minéralisation à uranium essentiellement réduite, alors que le gisement d’Imouraren est contenu dans une formation d’âge Jurassique sous forme de minéralisation uranifère majoritairement oxydée avec quelques poches de minéralisation réduite. La découverte de nouvelles concentrations d’uranium à l’Ouest de la faille d’Arlit et les différences entre les gisements dans le Carbonifère et le Jurassique, ont encouragé une réévaluation des modèles métallogéniques antérieurs. L’objectif est de déterminer si les différentes minéralisations uranifères ont été formées durant un même évènement diagénétique/hydrothermal en lien avec un épisode géotectonique majeur, ou si celles-ci sont polyphasées dans le temps, afin de proposer un modèle métallogénique global. Une approche multi-technique regroupant une étude détaillée de la diagenèse, des fluides, de la minéralisation, de la géochronologie et de la géothermométrie, a été appliquée afin de retracer l’histoire d’enfouissement du bassin et d’appréhender les conditions de dépôt de l’uranium. Deux phases principales de minéralisation uranifère se distinguent: (i) un épisode diagénétique/hydrothermal principal entre 100 et 135 Ma au cours duquel les minéraux primaires d’uranium et de cuivre précipitent en milieu réduit dans des conditions proches de l’enfouissement maximal (P : 80-120 bars, T : 115-150 °C), en relation avec les périodes de rift atlantique au Crétacé. (ii) une série de remaniement des minéraux primaires en milieu oxydant pour former des minéraux secondaires d’uranium, de vanadium et de cuivre en conditions supergènes liée à l’exhumation des séries depuis 50 Ma, lors des grandes phases d’oxydation connues en Afrique de l’Ouest. / The main U-deposits of Niger (Arlit, Akouta, and Imouraren) are all located in the Tim Mersoï Basin, east of the Arlit Fault. The deposits of Arlit and Akouta are hosted in Carboniferous formations and have a substantially reduced uranium mineralization, while the Imouraren deposit is contained in a Jurassic formation in the form of predominantly oxidized uranium mineralization with some pockets of reduced mineralization. New ore bodies discoveries west of the Arlit Fault in the regions of Arlit and Akouta and the differences between the U-deposits in the Carboniferous and Jurassic, have encouraged a reevaluation of the previous metallogenic models. The objective is to determine whether the uranium mineralizations of Tim Mersoï Basin were formed during the same diagenetic/hydrothermal event in relation with a major geotectonic event, or if they are polyphase over time, in order to propose a general metallogenic model. A multi-technique approach involving a detailed study of diagenesis, fluid circulations, mineralization, geochronology and geothermometry was applied to trace the burial history of the basin and constrain the P-T conditions of uranium deposition. Two main phases of uranium mineralization are distinguished: (i) A diagenetic/hydrothermal episode between 100 and 135 Ma in which primary uranium and copper minerals precipitate in reduced environment under conditions close to maximum burial (P : 80-120 bars, T : 115-150 °C), in relation with Atlantic rift periods during Cretaceous. (ii) A serie of remobilizations of primary uranium minerals in oxidizing environment to form secondary uranium, vanadium and copper minerals under supergene conditions related to uplift since 50 Ma, during the major events of oxidation in western Africa.

Está demonstrado em plantas atuais que níveis atmosféricos de CO2 e frequência estomática estão inversamente correlacionados. A utilização de dados estomáticos na calibração das curvas de CO2 paleoatmosférico do Fanerozoico tem sido eficiente não apenas para o Cenozoico, mas também apresenta excelente correspondência desde o Eodevoniano. Cutículas de glossopterídeas provenientes das jazidas de carvão de Faxinal (RS) e Figueira (PR), incluídas em níveis estratigráficos distintos da Formação Rio Bonito (Sakmariano e Artinskiano respectivamente), viabilizaram análises para floras desenvolvidas sob a vigência de megaciclo icehouse. Cabe ressaltar que o uso de glossopterídeas, classificadas dentro do grupo extinto das Pteridospermophyta, esbarra na impossibilidade de se estabelecer um equivalente ecológico atual, dada a ausência de relações taxonômicas, estruturais e ecológicas com grupos viventes. Portanto, optou-se por uma abordagem proposta por outros autores como alternativa para diferentes grupos de pteridospermas, que consistiu em comparar entre si resultados de análises estomáticas na morfo-espécie Glossopteris communis Feistmantel procedente de distintos níveis associados a carvões na Bacia do Paraná. O objetivo geral do presente estudo foi estabelecer possíveis relações entre os padrões estomáticos calculados e flutuações nos teores de CO2 paleoatmosférico. A metodologia consistiu em resgatar mecanica e quimicamente as cutículas da rocha matriz, clareá-las em solução de Schulze e montá-las em lâminas de gelatina glicerinada para observação em microscopia de luz transmitida. A observação deu-se com auxílio de filtro de contraste por interferência diferencial e as contagens foram feitas com o auxílio de programa para análise de imagens. As técnicas de estudo compreenderam cálculos de densidade estomática (DE- número de estômatos por unidade de área da folha) e índice estomático (IE- percentual de estômatos sobre o total de células epidérmicas). Os resultados obtidos foram de DE média= 234,73 e IE médio= 15,7 para a jazida de Faxinal (Sakmariano) e de DE média= 284,14 e IE= 18,9 para a jazida de Figueira (Artinskiano). Esses valores enquadram-se dentro da curva global de CO2 atmosférico para o Fanerozoico (modelo GEOCARB). As frequências estomáticas mais baixas das folhas do Faxinal com relação àquelas de Figueira foram relacionadas a processo de reversão temporária da tendência global de baixos teores de CO2 atmosférico para a base do Permiano. Essa reversão é atribuída à provável influência de fatores paleoecológicos locais relativos à grande extensão das turfeiras na parte sul da bacia, responsável pela emissão em larga escala de gases-estufa. Além disso, a flora de Faxinal está preservada em uma camada de tonstein, registro de atividade vulcânica que poderia ter afetado os níveis de CO2. Por outro lado, as turfeiras de registro muito esparso ocorrentes no nordeste da bacia, em intervalo mais jovem, por sua pequena extensão e ausência de indícios de vulcanismo, não alteraram o padrão paleoatmosférico. Estudos focados no final do Paleozoico têm especial relevância porque, nesse intervalo vigoravam, nas diferentes paleolatitudes, condições ambientais análogas àquelas ocorrentes na atualidade, como a existência de calotas de gelo nos pólos e períodos de aquecimento global. / In extant plants stomatal frequency and the concentration of the atmospheric CO2 have been shown to correlate inversely. The use of stomatal data to calibrate phanerozoic paleoatmospheric CO2 curves has been considered a reliable technique not only for the Cenozoic estimates but also for results obtained since the Early Devonian. Glossopterid cuticles from Faxinal and Figueira coalfields (respectively in Rio Grande do Sul and Paraná States) from distinct stratigraphic levels in the Rio Bonito Formation allowed stomatal counting for floras developed under icehouse megacycle. However, it is important to highlight that the efficiency of Glossopteris, classified in the extinct group of Pteridospermophyta, is restricted as paleo-CO2 proxy for the Paleozoic due to the difficulty of establishing a nearest living equivalent for it, given the lack of taxonomic, structural and ecological relationships with extant groups. Thus it was here adopted an alternative approach proposed by different authors analyzing other groups of pteridosperms, which consists in comparing results obtained from the morphospecies Glossopteris communis Feistmantel between two different coal levels in the Paraná Basin. The general aim of this study was to establish possible relations between the calculated stomatal patterns and the fluctuation in the paleoatmospheric CO2 levels. The methodology consisted in mechanically and chemically isolating the cuticles from the matrix rock, bleaching them with Schulze solution and then mounting glycerin jelly slides for observation in transmitted light microscopy. The microscopic observation was made using a differential interference contrast filter and the counting was carried out with the help of software for image analysis. The study techniques included the calculation of stomatal densities (SD- number of stomata per foliar area unit) and of stomatal indices (SI- a ratio of the number of the stomata to the total number of epidermal cells). The results were mean SD= 234.73 and mean SI= 15.7 in Faxinal coalfield (Sakmarian) and mean SD= 284.14 and SI= 18.9 in Figueira coalfield (Artinskian). These values agree with the curve of global atmospheric CO2 for the Phanerozoic (GEOCARB model). The lower stomatal frequencies detected at the climax of the coal interval (Faxinal coalfield, Sakmarian) when compared to the higher ones obtained in leaves from a younger interval (Figueira coalfield, Artinskian) could be attributed to temporarily high levels of atmospheric CO2. Therefore, the occurrence of an extensive peat generating event at the southern part of the basin and the consequent greenhouse gases emissions from this environment may have been enough to reverse regionally and temporarily the reduction trend in atmospheric CO2. Additionally, the Faxinal flora is preserved in a tonstein layer, which is a record of a volcanic activity that could also imply a rise in atmospheric CO2. During the Artinskian, the scarce generation of peat mires, as revealed by the occurrence of thin and discontinuous coal layers, and the lack of volcanism evidences would be insufficient to affect the general low CO2 trend. Studies focused in the Late Paleozoic are especially relevant because of the presently shared icehouse climate with glacial-interglacial cyclicity which includes times of global warming.

Orientador: Ruth Künzli / Banca: Rosângela Custódio Cortez Thomaz / Banca: João Osvaldo Rodrigues Nunes / Resumo: O objetivo deste trabalho é mostrar a contribuição que uma pesquisa arqueológica pode oferecer à compreensão da formação do espaço geográfico e suas transformações. Tanto para a Geografia quanto para a Arqueologia é fundamental o estudo das técnicas, pois é através delas que o homem pode medir seu nível cultural. Tentar entender e compreender que essas técnicas são a peça chave para saber quais eram os hábitos e costumes dos povos pré-históricos, pois através dessas técnicas é que podemos saber quais eram seu modo de vida e sua relação com o espaço ocupado. Com isso podemos ver que numa análise mais abrangente através do conhecimento de técnicas, podemos estar descrevendo os costumes dos povos que habitaram determinada região. Neste aspecto, o projeto tem por objetivo analisar o material arqueológico encontrado durante as escavações, procurando identificar, através de um sítio definido, que servirá como parâmetro, quais as técnicas utilizadas pelos povos pré-históricos que habitaram a região, bem como compreender e identificar qual a origem desses povos, e a que grupos pertenciam, bem como a forma pela qual eles se relacionavam com o meio natural para a construção do espaço geográfico no qual habitaram no passado. Identificando esses povos não apenas estaremos descobrindo uma parte de nossa própria história regional, bem como avançando na compreensão da evolução do homem enquanto agente transformador do espaço em que habitava e interagia. / Abstract: This work is a contribution to archaeological research that can provide the understanding about the formation of geographical space and their transformations. Both for the Geography and the Archeology the study of techniques is fundamental, for it is through them that man can measure their cultural level. Trying to understand and realize that these techniques are the key to what the habits and customs of prehistoric people were, because through these techniques is that we can know what were their way of life and their relation to space. With this we can see that in a more comprehensive analysis of their techniques we can describe the customs of peoples who inhabited a region. Here, the project aims to analyze the material found during the archaeological excavations, seeking to identify, through a established site to serve as a parameter to which techniques were used by prehistoric peoples who inhabited the region, and understand and identify which origin of these peoples and groups that belonged, and the way in which they interact to the natural environment for the construction of the geographical area in which they inhabited in the past. By identifying these people, we will not only discover a part of our regional history, as well as advancing the understanding of the evolution of man as an agent of transformation of the space in which they lived and interacted. / Mestre

Está demonstrado em plantas atuais que níveis atmosféricos de CO2 e frequência estomática estão inversamente correlacionados. A utilização de dados estomáticos na calibração das curvas de CO2 paleoatmosférico do Fanerozoico tem sido eficiente não apenas para o Cenozoico, mas também apresenta excelente correspondência desde o Eodevoniano. Cutículas de glossopterídeas provenientes das jazidas de carvão de Faxinal (RS) e Figueira (PR), incluídas em níveis estratigráficos distintos da Formação Rio Bonito (Sakmariano e Artinskiano respectivamente), viabilizaram análises para floras desenvolvidas sob a vigência de megaciclo icehouse. Cabe ressaltar que o uso de glossopterídeas, classificadas dentro do grupo extinto das Pteridospermophyta, esbarra na impossibilidade de se estabelecer um equivalente ecológico atual, dada a ausência de relações taxonômicas, estruturais e ecológicas com grupos viventes. Portanto, optou-se por uma abordagem proposta por outros autores como alternativa para diferentes grupos de pteridospermas, que consistiu em comparar entre si resultados de análises estomáticas na morfo-espécie Glossopteris communis Feistmantel procedente de distintos níveis associados a carvões na Bacia do Paraná. O objetivo geral do presente estudo foi estabelecer possíveis relações entre os padrões estomáticos calculados e flutuações nos teores de CO2 paleoatmosférico. A metodologia consistiu em resgatar mecanica e quimicamente as cutículas da rocha matriz, clareá-las em solução de Schulze e montá-las em lâminas de gelatina glicerinada para observação em microscopia de luz transmitida. A observação deu-se com auxílio de filtro de contraste por interferência diferencial e as contagens foram feitas com o auxílio de programa para análise de imagens. As técnicas de estudo compreenderam cálculos de densidade estomática (DE- número de estômatos por unidade de área da folha) e índice estomático (IE- percentual de estômatos sobre o total de células epidérmicas). Os resultados obtidos foram de DE média= 234,73 e IE médio= 15,7 para a jazida de Faxinal (Sakmariano) e de DE média= 284,14 e IE= 18,9 para a jazida de Figueira (Artinskiano). Esses valores enquadram-se dentro da curva global de CO2 atmosférico para o Fanerozoico (modelo GEOCARB). As frequências estomáticas mais baixas das folhas do Faxinal com relação àquelas de Figueira foram relacionadas a processo de reversão temporária da tendência global de baixos teores de CO2 atmosférico para a base do Permiano. Essa reversão é atribuída à provável influência de fatores paleoecológicos locais relativos à grande extensão das turfeiras na parte sul da bacia, responsável pela emissão em larga escala de gases-estufa. Além disso, a flora de Faxinal está preservada em uma camada de tonstein, registro de atividade vulcânica que poderia ter afetado os níveis de CO2. Por outro lado, as turfeiras de registro muito esparso ocorrentes no nordeste da bacia, em intervalo mais jovem, por sua pequena extensão e ausência de indícios de vulcanismo, não alteraram o padrão paleoatmosférico. Estudos focados no final do Paleozoico têm especial relevância porque, nesse intervalo vigoravam, nas diferentes paleolatitudes, condições ambientais análogas àquelas ocorrentes na atualidade, como a existência de calotas de gelo nos pólos e períodos de aquecimento global. / In extant plants stomatal frequency and the concentration of the atmospheric CO2 have been shown to correlate inversely. The use of stomatal data to calibrate phanerozoic paleoatmospheric CO2 curves has been considered a reliable technique not only for the Cenozoic estimates but also for results obtained since the Early Devonian. Glossopterid cuticles from Faxinal and Figueira coalfields (respectively in Rio Grande do Sul and Paraná States) from distinct stratigraphic levels in the Rio Bonito Formation allowed stomatal counting for floras developed under icehouse megacycle. However, it is important to highlight that the efficiency of Glossopteris, classified in the extinct group of Pteridospermophyta, is restricted as paleo-CO2 proxy for the Paleozoic due to the difficulty of establishing a nearest living equivalent for it, given the lack of taxonomic, structural and ecological relationships with extant groups. Thus it was here adopted an alternative approach proposed by different authors analyzing other groups of pteridosperms, which consists in comparing results obtained from the morphospecies Glossopteris communis Feistmantel between two different coal levels in the Paraná Basin. The general aim of this study was to establish possible relations between the calculated stomatal patterns and the fluctuation in the paleoatmospheric CO2 levels. The methodology consisted in mechanically and chemically isolating the cuticles from the matrix rock, bleaching them with Schulze solution and then mounting glycerin jelly slides for observation in transmitted light microscopy. The microscopic observation was made using a differential interference contrast filter and the counting was carried out with the help of software for image analysis. The study techniques included the calculation of stomatal densities (SD- number of stomata per foliar area unit) and of stomatal indices (SI- a ratio of the number of the stomata to the total number of epidermal cells). The results were mean SD= 234.73 and mean SI= 15.7 in Faxinal coalfield (Sakmarian) and mean SD= 284.14 and SI= 18.9 in Figueira coalfield (Artinskian). These values agree with the curve of global atmospheric CO2 for the Phanerozoic (GEOCARB model). The lower stomatal frequencies detected at the climax of the coal interval (Faxinal coalfield, Sakmarian) when compared to the higher ones obtained in leaves from a younger interval (Figueira coalfield, Artinskian) could be attributed to temporarily high levels of atmospheric CO2. Therefore, the occurrence of an extensive peat generating event at the southern part of the basin and the consequent greenhouse gases emissions from this environment may have been enough to reverse regionally and temporarily the reduction trend in atmospheric CO2. Additionally, the Faxinal flora is preserved in a tonstein layer, which is a record of a volcanic activity that could also imply a rise in atmospheric CO2. During the Artinskian, the scarce generation of peat mires, as revealed by the occurrence of thin and discontinuous coal layers, and the lack of volcanism evidences would be insufficient to affect the general low CO2 trend. Studies focused in the Late Paleozoic are especially relevant because of the presently shared icehouse climate with glacial-interglacial cyclicity which includes times of global warming.

Está demonstrado em plantas atuais que níveis atmosféricos de CO2 e frequência estomática estão inversamente correlacionados. A utilização de dados estomáticos na calibração das curvas de CO2 paleoatmosférico do Fanerozoico tem sido eficiente não apenas para o Cenozoico, mas também apresenta excelente correspondência desde o Eodevoniano. Cutículas de glossopterídeas provenientes das jazidas de carvão de Faxinal (RS) e Figueira (PR), incluídas em níveis estratigráficos distintos da Formação Rio Bonito (Sakmariano e Artinskiano respectivamente), viabilizaram análises para floras desenvolvidas sob a vigência de megaciclo icehouse. Cabe ressaltar que o uso de glossopterídeas, classificadas dentro do grupo extinto das Pteridospermophyta, esbarra na impossibilidade de se estabelecer um equivalente ecológico atual, dada a ausência de relações taxonômicas, estruturais e ecológicas com grupos viventes. Portanto, optou-se por uma abordagem proposta por outros autores como alternativa para diferentes grupos de pteridospermas, que consistiu em comparar entre si resultados de análises estomáticas na morfo-espécie Glossopteris communis Feistmantel procedente de distintos níveis associados a carvões na Bacia do Paraná. O objetivo geral do presente estudo foi estabelecer possíveis relações entre os padrões estomáticos calculados e flutuações nos teores de CO2 paleoatmosférico. A metodologia consistiu em resgatar mecanica e quimicamente as cutículas da rocha matriz, clareá-las em solução de Schulze e montá-las em lâminas de gelatina glicerinada para observação em microscopia de luz transmitida. A observação deu-se com auxílio de filtro de contraste por interferência diferencial e as contagens foram feitas com o auxílio de programa para análise de imagens. As técnicas de estudo compreenderam cálculos de densidade estomática (DE- número de estômatos por unidade de área da folha) e índice estomático (IE- percentual de estômatos sobre o total de células epidérmicas). Os resultados obtidos foram de DE média= 234,73 e IE médio= 15,7 para a jazida de Faxinal (Sakmariano) e de DE média= 284,14 e IE= 18,9 para a jazida de Figueira (Artinskiano). Esses valores enquadram-se dentro da curva global de CO2 atmosférico para o Fanerozoico (modelo GEOCARB). As frequências estomáticas mais baixas das folhas do Faxinal com relação àquelas de Figueira foram relacionadas a processo de reversão temporária da tendência global de baixos teores de CO2 atmosférico para a base do Permiano. Essa reversão é atribuída à provável influência de fatores paleoecológicos locais relativos à grande extensão das turfeiras na parte sul da bacia, responsável pela emissão em larga escala de gases-estufa. Além disso, a flora de Faxinal está preservada em uma camada de tonstein, registro de atividade vulcânica que poderia ter afetado os níveis de CO2. Por outro lado, as turfeiras de registro muito esparso ocorrentes no nordeste da bacia, em intervalo mais jovem, por sua pequena extensão e ausência de indícios de vulcanismo, não alteraram o padrão paleoatmosférico. Estudos focados no final do Paleozoico têm especial relevância porque, nesse intervalo vigoravam, nas diferentes paleolatitudes, condições ambientais análogas àquelas ocorrentes na atualidade, como a existência de calotas de gelo nos pólos e períodos de aquecimento global. / In extant plants stomatal frequency and the concentration of the atmospheric CO2 have been shown to correlate inversely. The use of stomatal data to calibrate phanerozoic paleoatmospheric CO2 curves has been considered a reliable technique not only for the Cenozoic estimates but also for results obtained since the Early Devonian. Glossopterid cuticles from Faxinal and Figueira coalfields (respectively in Rio Grande do Sul and Paraná States) from distinct stratigraphic levels in the Rio Bonito Formation allowed stomatal counting for floras developed under icehouse megacycle. However, it is important to highlight that the efficiency of Glossopteris, classified in the extinct group of Pteridospermophyta, is restricted as paleo-CO2 proxy for the Paleozoic due to the difficulty of establishing a nearest living equivalent for it, given the lack of taxonomic, structural and ecological relationships with extant groups. Thus it was here adopted an alternative approach proposed by different authors analyzing other groups of pteridosperms, which consists in comparing results obtained from the morphospecies Glossopteris communis Feistmantel between two different coal levels in the Paraná Basin. The general aim of this study was to establish possible relations between the calculated stomatal patterns and the fluctuation in the paleoatmospheric CO2 levels. The methodology consisted in mechanically and chemically isolating the cuticles from the matrix rock, bleaching them with Schulze solution and then mounting glycerin jelly slides for observation in transmitted light microscopy. The microscopic observation was made using a differential interference contrast filter and the counting was carried out with the help of software for image analysis. The study techniques included the calculation of stomatal densities (SD- number of stomata per foliar area unit) and of stomatal indices (SI- a ratio of the number of the stomata to the total number of epidermal cells). The results were mean SD= 234.73 and mean SI= 15.7 in Faxinal coalfield (Sakmarian) and mean SD= 284.14 and SI= 18.9 in Figueira coalfield (Artinskian). These values agree with the curve of global atmospheric CO2 for the Phanerozoic (GEOCARB model). The lower stomatal frequencies detected at the climax of the coal interval (Faxinal coalfield, Sakmarian) when compared to the higher ones obtained in leaves from a younger interval (Figueira coalfield, Artinskian) could be attributed to temporarily high levels of atmospheric CO2. Therefore, the occurrence of an extensive peat generating event at the southern part of the basin and the consequent greenhouse gases emissions from this environment may have been enough to reverse regionally and temporarily the reduction trend in atmospheric CO2. Additionally, the Faxinal flora is preserved in a tonstein layer, which is a record of a volcanic activity that could also imply a rise in atmospheric CO2. During the Artinskian, the scarce generation of peat mires, as revealed by the occurrence of thin and discontinuous coal layers, and the lack of volcanism evidences would be insufficient to affect the general low CO2 trend. Studies focused in the Late Paleozoic are especially relevant because of the presently shared icehouse climate with glacial-interglacial cyclicity which includes times of global warming.

Les sédiments marins des sites de forage U1460 et U1461 recueillis pendant l’expédition IODP 356 constituent l’un des rares enregistrements au niveau du plateau australien Nord-Ouest. Ils fournissent des informations sur l’intensité de l’aridité en Australie pendant les principaux cycles glaciaires-interglaciaires du Quaternaire, en raison de leur proximité avec le continent. Outre la reconstitution du climat continental, ces sériés sédimentaires permettent de reconstruire le fonctionnement des courants océaniques passés au large de la côte Ouest australienne.Sur le site U1461, la chronostratigraphie a permis d’identifier deux glaciations majeures du Pléistocène (MIS 2 et MIS 12). Les assemblages de la microfaune benthique (principalement les foraminifères benthiques, les coraux et les bryozoaires) ont été analysés afin de reconstruire les paléo-environnements et les paléo-profondeurs du milieu sédimentaire. Malgré la présence d’un hiatus dans l’enregistrement (incluant une partie du MIS 2 et l’ensemble du MIS 3-MIS 7), l’excellente conservation du contenu de la microfaune benthique suggère que les sédiments préservés peuvent être considérés comme in situ.Sur ce même site, les isotopes du Nd et du Sr ainsi que d’autres traceurs (à citer) déterminés dans les sédiments indiquent d’une part que les apports fluviaux ont probablement été réduits en raison de l'aridité accrue au cours du MIS 12, et d’autre part que la source des sédiments (principalement transportés par voie atmosphérique) pourrait se trouver au centre (Lake Eyre) ou à l’Est du continent (Murray-Darling Basin) australien. Le MIS 2 s’avère être l’une des périodes les plus sèches enregistrées en Australie avec des sources de poussière mixtes provenant de l’Est et de l’Ouest du continent. Des conditions plus humides pouvant correspondre au maximum de la Mousson d’été Indo-Australienne ont suivi après le maximum glaciaire.Sur le site U1460, une étude approfondie des assemblages de la méiofaune benthique et de l'abondance d’une espèce de foraminifère planctonique (Globorotalia mernardii ) donne de bons indices prouvant un changement majeur et soudain de la circulation océanique au cours de l'événement de Bruhnes Moyen (Mid-Bruhnes Event, MIS 11). L'une des hypothèses privilégiées pour ce changement pendant cette période serait liée à la mise en place du courant de Leeuwin moderne. / IODP Expedition 356 Site U1461 and Site U1460 represents ones of the few records in the NW sector of the Australian shelf that provides information about aridity fluctuations in Australia during major glacial cycles of the Quaternary because of their proximity to the continent. At the same time, they are also providing information about former ocean currents around Australia.For the Site U1461 a combination of chronostratigraphic indicators revealed the (partial) preservation of two major glaciations (MIS 2 and MIS 12) in the sedimentary record. The faunal content (mainly benthic foraminifera, corals and bryozoans) was analyzed for estimating paleo-environments and depths in order to determine if these sediments have been remobilized by reworking processes. Despite the occurrence of a depositional hiatus (that includes part of the MIS 2 and the whole MIS 3-MIS 7 time interval), the excellent preservation of faunal content suggests that the preserved sediment can be considered in situ.The geochemical composition of the sediments (Nd and Sr radiogenic isotopes and major elements) measured in the U1461 indicates, riverine input was likely reduced because of enhanced aridity during the MIS 12, and the sediment provenance (mainly atmospheric dust) might come from the Central (Lake Eyre) or the eastern (Murray Darling Basin) parts of the continent. MIS 2 is confirmed to be one of the driest periods recorded in Australia with mixed dust sources from the eastern and western parts of the continent. More humid conditions followed the glacial maximum that might correspond to the peak of the Indian-Australian Summer Monsoon.For the Site U1460 a thorough study of the benthic meiofauna assemblages and of the abundance of G. mernardii give some strong evidences of a major and suddenly change in the oceanographic circulation during the Mid-Bruhnes –Event (MIS 11). One of the preferred hypothesis for this change is related to the set-up of the modern Leeuwin Current at this period.

L’objet de cette recherche concerne le Japon entre les années 1953 et 1976. Elle utilise les essais du philosophe Ōmori Shōzō et expose la nature de son concept d’« apparaitre immé-diat (jika ni tachi arawareru) ». Je mets en évidence les relations possibles trouvées entre ce concept et le concept d’être. En amont et mis en rapport avec ce pur travail d’ontologie, je présente une partie de l’histoire philosophique du Japon. Ainsi cette recherche expose le ré-seau des concepts fondamentaux qui sont attachés à l’apparaitre. C’est-à-dire principale-ment :la perception, la forme, le paysage, le langage, l’attitude, l’organisation unifiée et l’immédiateté. De cette manière, notre texte aborde le problème général de la « réalité », à savoir la saisie logique et relationnelle qu’on peut trouver entre esprit et chose. Notre hypo-thèse est que l’apparaitre permet une révision des structures fondamentales qui légifèrent, habituellement, la construction de la « réalité ». Il s’agit de revisiter le rapport possible entre la chose et sa représentation ou encore, le monde et son image. De cette façon, puisant dans les ressources japonisantes de l’apparaitre, cette recherche tente d’enrichir le sens du voca-bulaire philosophique spécifique de la philosophie de l’esprit. Notre travail soutient que la Spaltung Philosophie, considérée comme initiée par Descartes, n’est pas défendable. À la vue des apories actuelles de ce débat et la lecture de Ōmori Shōzō, je montre que l’hypothèse de la scission entre le corps et l’esprit a été contestée dans la philosophie japonaise d’après-guerre. / The object of this research concerns Japan between 1953 and 1976. Using the essays of the philosopher Ōmori Shōzō, I expose the nature of his concept of "apparaitre (jika ni tachi-arawareru)." I highlight the possible relations found between this concept and the concept of being. By tracing this pure ontological framework, I present a part of the philosophical histo-ry of Japan. Thus, the primary purpose of this research is to unfold the network of fundamen-tal concepts that are attached to the apparaitre, including: perception, form, paysage, lan-guage, attitude, organisation unifiée and immediacy. This text makes a critical approach to the general problem of "reality" namely the logical, relational comprehension that can be found between mind and thing. My hypothesis is that the apparaitre allows a revision of the fundamental metaphysical structures that usually legislate the construction of "reality," by examining the possible relationship between a thing and its representation, or the world and its image. In drawing on the Japanese resources for understanding the apparaitre, this re-search aims at enriching the meaning the specific philosophical vocabulary in the contempo-rary philosophy of mind. Most importantly, it also argues that the Spaltung philosophy, con-sidered to be initiated by Descartes, is not defensible. In view of the current aporias of this debate and my reading of Ōmori, I show that the hypothesis of the split between body and mind has been sufficiently challenged, and critically rearticulated in contemporary Japanese philosophy. / Doctorat en Philosophie / info:eu-repo/semantics/nonPublished

The objective of this research was to determine the environmental and social factors that led to the shift of settlement patterning from agro-pastoral in the late Neolithic to hillort sites at the turn of the Early Bronze Age and why burial mounds (tumuli) were erected further than anticipated from corresponding hillort sites in the Shkodra Plain region in Northern Albania. Geospatial techniques were used to examine 168 tumuli and seven hillort sites. These were mapped to examine visibility, viewshed, slope, and potential prehistoric networks. Based on the landscape visibility GIS results, it was found that hillort sites and tumuli were part of an social landscape that thrived on trade. It was determinable that the shift of the social landscape was related to Northern trade routes and probable changes in paleo-lake levels. This new evidence provides insight to Albanian prehistoric culture and has implications to related studies in the Balkans.

Elevation, longitudinal profile, and Schmidt hammer data indicate that strath terraces (specifically the lower elevation terraces) mapped in the Fremont River drainage of Capitol Reef National Park are correlative to the terraces of the smaller Pleasant Creek drainage located approximately ten miles to the south. This correlation suggests that drainage development in this area of the Colorado Plateau was strongly dependent upon a regional-scale forcing mechanism (e.g. climate) rather than strictly independent basin-scale processes. Elevations of mapped strath terraces and their associated black volcanic boulder deposits were calculated from geologic maps, Digital Elevation Models (DEM), and Digital Orthophoto Quadrangles of the Fruita and Golden Throne Quadrangles, Wayne and Garfield Counties, Utah. Terraces in both drainages were placed into twenty foot elevation bins and then gathered into larger terrace levels based upon population breaks and the degree of weathering as seen from Schmidt hammer hardness data. Comparison of the two datasets indicate that the two lowest terrace levels of the Fremont River compare well with the two terrace levels of Pleasant Creek both in elevation above the present stream bed and in Schmidt hammer hardness measurements. Our data demonstrate that the Fremont River drainage is likely much older than the smaller Pleasant Creek drainage. Further, correlative terrace data strongly suggests that glacial-interglacial climate forcing played a dominant role in the landscape evolution of both drainages and by inference, the broader Colorado Plateau. Terrace elevation data were compared with recently published cosmogenic ages for several terrace deposits located within the Fremont River drainage. This comparison provides compelling evidence that highest concentrations of preserved terraces may be time correlative with discrete isotopic stages associated with glacial maximum and/or deglacial conditions. Finally, our data also demonstrate that in this area of the Colorado Plateau incision rates are on the order of ~60 to 85 cm/ka, which is on the high end of reported rates from other researchers.

Previous biostratigraphic studies in the Indian Ocean, equatorial Pacific, Atlantic Ocean and the Caribbean Sea document the temporal disappearance of Reticulofenestra pseudoumbilicus in the late Miocene (Tortonian age). This interval has been subsequently defined as the R. pseudoumbilicus paracme. While the cause of the event remains unknown, the geographical extent and global synchronicity of the interval represent an open subject for research. Answers to these questions could help establish the biostratigraphic reliability of the interval and its use for global correlation. In this study, 49 deep-sea drilling sites spread across all major ocean basins were compiled into a biostratigraphic database and studied to evaluate the global extent and timing of the R. pseudoumbilicus paracme. To ensure accurate comparison of the studied sites, the timing of the event was estimated at all sites using the age estimates generated through Undatable MatLab software, which made use of established nannofossil bioevents as age-depth tie points for the analysis. Ages of all nannofossil bioevents were updated to the latest geological time scale. This systematic analysis reveals a prominent distribution of the paracme in the tropical and subtropical regions. The timing of the event in the tropical region appears to be synchronous, with the base around 8.8 Ma and the top of the event around 7.2 Ma. Sites in the equatorial Pacific, central Atlantic and the Indian Oceans record a similar duration of the event. The paracme had a shorter duration towards the southern higher latitudes. Although timings in southern high latitudes are diachronous compared to the tropics, the duration is consistent between sites (Sites 1088 and 1264) in the southern South Atlantic, thereby establishing a new time frame for the event in the region. This study narrows down on ODP Site 806 for a critical evaluation of the nannofossil assemblages, accumulation rates and Reticulofenestra size variation in the late Miocene, including the paracme. Thirty-four samples were collected and analysed for absolute abundance and nannofossil accumulation rates (NAR). Absolute abundance and NAR reveal three distinct stages, herein described as generally low, high, and “crashed” export production of nannofossils. The period of high NAR is characteristic of the late Miocene biogenic bloom interval (ca. 9–4.4 Ma). Importantly, the R. pseudoumbilicus paracme does not only coincide with the start of the biogenic bloom but it was also associated with remarkable changes in Reticulofenestra assemblages. Just before the base of the paracme, all except the smallest (&lt;3 µm in coccolith size) Reticulofenestra groups experienced a sharp decline in abundance. Subsequently, the relative abundance of the Reticulofenestra morphospecies indicates the dominance of bloom-forming small and medium Reticulofenestra during the late Miocene biogenic bloom interval. The end of the biogenic bloom interval is concurrent with a decrease in the contribution of small Reticulofenestra. The exact biotic and abiotic processes that led to these major shifts in plankton composition are yet to be discovered, but the findings presented herein show that the mechanisms behind the temporary disappearance of R. pseudoumbilicus in the tropics most likely involved the interplay between a broad range of ecological changes and evolutionary processes affecting the Reticulofenestra assemblages. / <p>The work for this thesis was financially supported by the Erasmus Mundus Joint Master Degree PANGEAprogramme.</p>