Orientadores: Julio Cesar Hadler Neto, Peter Christian Hackspacher / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-11T05:57:37Z (GMT). No. of bitstreams: 1 Palissari_Rosane_D.pdf: 15939989 bytes, checksum: f455fc1254ec2dd67bb39d1df46cce88 (MD5) Previous issue date: 2007 / Resumo: O Método dos Traços de Fissão (MTF)é uma das técnicas mais poderosas usadas para descrever as histórias térmicas de rochas presentes na camada da superfície terrestre,sob condições de baixa temperatura.Se a rocha hospedeira teve a temperatura elevada em um dado período,os traços de fissão que se formaram desde então,são encurtados irreversivelmente ou apagados (os traços sofrem annealing ),como conseqüência de um processo de difusão termicamente ativada. Os minerais mais comumente utilizados no MTF são a apatita e o zircão,sendo este último o objetivo deste trabalho.O zircão é sensível ao annealing térmico sob temperaturas mais altas que a temperatura de fechamento da apatita,que é aproximadamente 120 o C . As características do annealing dos traços de fissão em zircão têm sido obtidas utilizando-se dados de experimentos de laboratório,que são executados em tempos menores que 1 ano,e comumente em tempos ainda menores.Estes dados são usados para calibrar modelos de annealing empíricos,que descrevem a dependência do encurtamento dos traços com o tempo e a temperatura.No entanto,um problema de ordem prática é a incerteza introduzida na extrapolação para tempos geológicos (10 6 ¿ 10 8 anos),através dos modelos calibrados pelos dados de laboratório (<1 ano). Um dos objetivos deste estudo é fornecer condições de contorno adicionais para a faixa de tempo-temperatura da zona de annealing do zircão,através de dados de zircões de poços, cujas amostras foram expostas a temperaturas estáveis por ~1 milhão de anos.Desta forma, o problema da extrapolação é abordado explicitamente ajustando-se os modelos a dados geológicos. Vários modelos de annealing foram propostos na literatura de traços de fissão.A formulação básica destes modelos baseia-se na equação de Arrhenius e foi apresentada por Laslett et al.(1987).Existem outros modelos de annealing que são baseados no mesmo princípio:Crowley et al.(1991);Laslett e Galbraith (1996);Rahn et al.(2004)e Yamada et al. (2007).Estes modelos têm sido usados preferencialmente,uma vez que inúmeros fenômenos, desde a formação dos traços até o ataque químico,não são bem entendidos ainda.orém,dois outros modelos calibrados no presente trabalho (Carlson,1990;Guedes et al.,2005a), procuram estabelecer uma correlação direta entre seus parâmetros e os fenômenos envolvidos.Os ajustes dos vários modelos foram comparados entre si,levando-se em conta considerações estatísticas. Além das calibrações efetuadas ajustando-se os modelos a dados geológicos, foram abordadas comparações de previsões dos modelos (relacionadas com as fronteiras da Zona de Annealing Parcial)com outros dados geológicos baseados em densidades de traços de fissão / Abstract: Fission-track (FT)analysis has developed into one of the most useful technique used to constrain the low-temperature thermal history of rocks in the upper part of the Earth's crust.If a host rock is subjected to elevated temperatures,fission tracks that have formed up to that point in time are shortened irreversibly or annealed,as a consequence of a thermally activated diffusion process. The most commonly analysed minerals are apatite and zircon and the latter is the focus of this work,since this mineral is sensitive to thermal annealing at higher temperatures,while the close temperature for apatite is around 120 o C. Short-term annealing characteristics of FT in zircon are generally based on laboratory experiments which are performed on timescales of less than 1 year,and typically much less. These data have been used to calibrate annealing empirical models,that describe the temperature and time dependence of fission track shortening.However,a practical problem is the uncertainty introduced through the extrapolation of laboratory calibrated models (<1 year)to geological timescales (10 6 ¿ 10 8 years). One of the purpose of this study is to give further constraints on the temperature range of the zircon annealing zone over a geological time scale using zircons data from boreholes,which samples have been exposed to a stable temperature for ~1 Ma.In this way,the extrapolation problem is explicity adressed by fit the zircon annealing models with geological timescale data. Several empirical models formulations have been proposed to perform these calibrations and have been compared in this work.The basic formulation is an Arrhenius-type model and is given by Laslett et al.(1987).There are other annealing models which are based on the same general formulation:Crowley et al.(1991);Laslett and Galbraith (1996);Rahn et al.(2004)and Yamada et al.(2007).These models equations have been preferred due to the great number of fenomena from track formation to chemical etching that are not well understood.However,two other calibrated models in this work (Carlson,1990;Guedes et al.,2005a)try to stablish a direct correlation between their parameters and the related fenomena.Several model fits are compared by themselves,considering statistical data. Besides calibrating annealing models with geological timescale data,model predictions (related with Parcial Annealing Zone boundaries)were compared with another geological data / Doutorado / Geofísica Nuclear / Doutor em Ciências

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The Paparoa Metamorphic Core Complex developed in the Mid-Cretaceous due to continental extension conditioning the crust for the eventual breakup of the Gondwana Pacific Margin, which separated Australia and New Zealand. It has two detachment systems: the top-NE-displacing Ohika Detachment at the northern end of the complex and the top-SW-displacing Pike Detachment at the southern end of the complex. The structure is rather unusual for core complexes worldwide, which are commonly characterised by a single detachment system. Few suggestions for the kinematics of the core complex development have been made so far. In this study structural-, micrographic- and fission track analyses were applied to investigate the bivergent character and to constrain the kinematics of the core complex. The new results combined with reinterpretations of previous workers’ observations reveal a detailed sequence of the core complex exhumation and the subsequent development. Knowledge about the influence and the timing of the two respective detachments is critical for understanding the structural evolution of the core complex. The syntectonic Buckland Granite plays a key role in the determination of the importance of the two detachment systems. Structural evidence shows that the Pike Detachment is responsible for most of the exhumation, while the Ohika Detachment is a mere complexity. In contrast to earlier opinions the southwestern normal fault system predates the northeastern one. The Buckland Pluton records the ceasing pervasive influence of the Pike Detachment, while activity on the Ohika Detachment had effect on the surface about ~8 Ma later. Most fission track ages are not related to the core complex stage, but reflect the younger late Cretaceous history. They show post core complex burial and renewed exhumation in two phases, which are regionally linked to the development of the adjacent Paparoa Basin and the Paparoa Coal Measures to the southwest and to the inception of seafloor spreading in the Tasman Sea in a larger context.

Les variations latérales d'exhumation de l'Himalaya sont peu documentées, notamment dans la partie est. Dans ce mémoire, l'évolution de la chaîne himalayenne est étudiée à partir de trois coupes réalisées dans le bassin d'avant-pays mio-pliocène où l'âge des sédiments a été déterminé par magnétostratigraphie. La contribution des différents domaines sources ainsi que leur exhumation ont été définies par des analyses géochimiques (εNd) et de thermochronologie détritique (apatite et zircon). Dans la partie orientale, nos observations suggèrent que les surrections concomitantes du plateau du Shillong et du prisme Indo-Birman ont repoussé le Brahmapoutre vers 7 Ma le long du front de la chaîne himalayenne. Les résultats des analyses de thermochronologie détritique soulignent une dynamique et des vitesses d'exhumation (1,7 km/Ma) semblables à celles de la partie centrale de la chaîne, en dépit de précipitations plus intenses et malgré la présence du plateau du Shillong au sud qui pourrait avoir absorbé une partie du raccourcissement tectonique. En revanche, l'installation d'une exhumation contrastée semble légèrement plus tardive que dans la partie centrale et ouest de la chaîne. Enfin, ces travaux suggèrent qu'au niveau de la syntaxe orientale il a existé un temps de latence d'au moins 3 Ma avant l'installation d'une rétroaction tectonique-érosion dans le massif du Namche Barwa liée à l'installation d'un drainage transverse à la chaîne. Au sein même de la partie centrale de la chaîne des variations latérales d'exhumation ont été mises en évidence, notamment, la mise en place au Népal occidental d'une exhumation rapide, reconnue dès 13 Ma, alors que celle-ci semble plus tardive dans la partie orientale du Népal. L'étude de la coupe occidentale a montré que le réseau de drainage du paléo-Indus est stable dans le bassin d'avant-pays depuis le Miocène moyen. En revanche, la proportion de matériaux provenant de l'Himalaya augmente à partir du Pliocène et ceci de manière généralisée le long de la partie ouest de la chaîne, suggérant un changement drastique des conditions d'exhumation de la chaîne. L'exhumation de la chaîne himalayenne apparaît donc comme étant segmentée latéralement. La mise en place d'une exhumation contrastée et diachrone le long de la chaîne ne semble donc pas liée à d'éventuels changements climatiques qui auraient affecté la chaîne de manière globale. La dynamique d'exhumation du prisme himalayen observée actuellement semble donc liée à des hétérogénéités de la croûte indienne, qui contrôlerait la mise en place des structures profondes de la chaîne. / From west to east along the Himalayan range, exhumation rates are variable and remain poorly constrained for the most part, especially in the eastern part of the mountain belt. To better understand their variability and to determine the influence of climatic and tectonic control, this thesis investigates the evolution of the range thanks to samples collected from three sections located in the eastern, central and western parts of the Mio-Pliocene Himalayan foreland basin. In these sections, sediment depositional ages were determined using magnetostratigraphy. Sediment provenance and contribution of the main litho-tectonic source-rock units were identified using geochemical analyses (Nd), while exhumation rates were determined with detrital apatite and zircon thermochronology. In the eastern part of the Himalaya, our results from the Kameng section in Arunachal Pradesh suggest that the surface uplift of both the Shillong Plateau and the Indo-Burman range have pushed the Brahmaputra River to the north, in front of the Himalayan range at about 7 Ma. Miocene-Pliocene exhumation rates inferred from detrital thermochronology are on the order of 1.7 km/Myr for the fastest exhuming areas, which is close to the rates reported for the central part of the range. Therefore, the distribution of precipitation, as well as the Shillong Plateau uplift which may have modified the convergence rate between the Indian and Eurasian plates, seem to have minor influence on the exhumation of eastern Himalaya. However, the onset of contrasting exhumation seems to have begun somewhat earlier than in the western and central parts of the range. In addition, our results highlight a 3 Myr time-lag between the installation of the Brahmaputra as a trunk river in the eastern syntaxes, and the onset of a fast exhumation there. Within the central part of the Himalaya, our work along the Muksar section in eastern Nepal documents lateral variations in exhumation rates, as western Nepal has been exhuming rapidly since 13 Ma, whereas the onset of fast exhumation seems to have occured later in eastern Nepal. Our results from the Chinji section in Pakistan, in western Himalaya, suggest that the Indus drainage network in the foreland basin has been stable since the middle Miocene. However, the Himalayan source contribution has been increasing since the Pliocene all along the western part of the range, and this suggests that a drastic change in the exhumation dynamics of the range occurred at that time. The Himalayan exhumation seems to be divided into independent segments along the range. The lateral variability in exhumation rates and timing of changes in exhumation rates do not seem to be linked to climatic change, which should produce a global response of the range. The exhumation dynamics is more likely to be linked to the tectonics structuring the wedge, possibly controlled by the crustal heterogeneity within the Indian plate.

Made available in DSpace on 2014-06-11T19:32:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-12-12Bitstream added on 2014-06-13T19:42:57Z : No. of bitstreams: 1 ribeiro_lfb_dr_rcla.pdf: 2783705 bytes, checksum: e1a426bdf710fbec9239ad48c9b2b00a (MD5) / O embasamento cristalino precambriano no sudeste do Brasil registra uma história tectônica fanerozóica que compreende uma série de reativações tectônicas caracterizadas por soerguimentos, subsidências e reativações de falhas. Para quantificar, datar e associar estas reativações com os eventos tectônicos regionais foram realizadas análises de caráter multidisciplinar, que consistem em reconhecimento de superfície erosivas, bem como delimitação e reconhecimento de depósitos correlativos. Com o intuito de reconhecer e quantificar feições de caráter rúptil, foi realizada análise dinâmica de falhas que inclui paleotensões e reconhecimento da rugosidade de clastos. A interação destas metodologias necessitou de uma associação temporal dos eventos, para isto foi feita datações pelo método Ar/Ar em material de falha e traços de fissão em apatitas próximo a falhas. Os resultados do campo de esforços com a geomorfologia permitiram definir cinco domínios morfoestruturais principais, onde foram registrados antigos eventos tectônicos recorrentes ao longo do Fanerozóico. Estes domínios foram denominados de acordo com o reconhecimento geográfico já proposto para a área, assim temos: A serrania de São Roque, O Planalto de Jundiaí, Mantiqueira Ocidental e Depressão de Cambuí e Planalto de Campos do Jordão. Os episódios tectônicos associados a estes domínios estão relacionados a soerguimentos e nos domínios Serrania de São Roque e Planalto de Jundiaí a geração e deformação de materiais de falha (pseudotaquilitos). Estes soerguimentos preservaram paleosuperfícies erosivas em cotas mais altas, que são indicativas de antigos ciclos de erosão, estas são observadas, principalmente nos domínios Mantiqueira Ocidental e Planalto de Campos do Jordão... / Phanerozoic tectonic histories of basement is registred many reactivations of faults, uplifts and subsidence. To quantify, dater and to associate this reactivations with tectonics events are multidisciplinary analyses, consists relief analysis, paleostress analysis, and structural analysis of faults, fission track and Ar/Ar ages. The results to permit subdivide area in five domains, to registry uplift and reactivation of faults. This faults to origin pseudotachylytes, these rocks . The uplift to basement relation with subsidence of Parana basin showing one complex relation between the basement and the deposition of Parana basin. The evolution of this basin seems to have been strongly influenced by compressive and distensive events associated to the subduction of Panthalassan plate under the southwestern, Gondwana margin, reflected as important unconformities in the stratigraphic framework of the Parana basin the elucidation of the uplift and denudation histories of the basement shield is crucial to the understanding of these tectonics effects.

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Orientador: Peter Christian Hackspacher / Banca: Julio César Hadler Neto / Banca: Cláudio Coelho de Lima / Banca: Iandara Alves Mendes / Banca: Norberto Morales / Resumo: O embasamento cristalino precambriano no sudeste do Brasil registra uma história tectônica fanerozóica que compreende uma série de reativações tectônicas caracterizadas por soerguimentos, subsidências e reativações de falhas. Para quantificar, datar e associar estas reativações com os eventos tectônicos regionais foram realizadas análises de caráter multidisciplinar, que consistem em reconhecimento de superfície erosivas, bem como delimitação e reconhecimento de depósitos correlativos. Com o intuito de reconhecer e quantificar feições de caráter rúptil, foi realizada análise dinâmica de falhas que inclui paleotensões e reconhecimento da rugosidade de clastos. A interação destas metodologias necessitou de uma associação temporal dos eventos, para isto foi feita datações pelo método Ar/Ar em material de falha e traços de fissão em apatitas próximo a falhas. Os resultados do campo de esforços com a geomorfologia permitiram definir cinco domínios morfoestruturais principais, onde foram registrados antigos eventos tectônicos recorrentes ao longo do Fanerozóico. Estes domínios foram denominados de acordo com o reconhecimento geográfico já proposto para a área, assim temos: A serrania de São Roque, O Planalto de Jundiaí, Mantiqueira Ocidental e Depressão de Cambuí e Planalto de Campos do Jordão. Os episódios tectônicos associados a estes domínios estão relacionados a soerguimentos e nos domínios Serrania de São Roque e Planalto de Jundiaí a geração e deformação de materiais de falha (pseudotaquilitos). Estes soerguimentos preservaram paleosuperfícies erosivas em cotas mais altas, que são indicativas de antigos ciclos de erosão, estas são observadas, principalmente nos domínios Mantiqueira Ocidental e Planalto de Campos do Jordão... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Phanerozoic tectonic histories of basement is registred many reactivations of faults, uplifts and subsidence. To quantify, dater and to associate this reactivations with tectonics events are multidisciplinary analyses, consists relief analysis, paleostress analysis, and structural analysis of faults, fission track and Ar/Ar ages. The results to permit subdivide area in five domains, to registry uplift and reactivation of faults. This faults to origin pseudotachylytes, these rocks . The uplift to basement relation with subsidence of Parana basin showing one complex relation between the basement and the deposition of Parana basin. The evolution of this basin seems to have been strongly influenced by compressive and distensive events associated to the subduction of Panthalassan plate under the southwestern, Gondwana margin, reflected as important unconformities in the stratigraphic framework of the Parana basin the elucidation of the uplift and denudation histories of the basement shield is crucial to the understanding of these tectonics effects. / Doutor

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Ce travail de thèse concerne une transversale complète des Pyrénées centro-occidentales, où on a combiné la thermochronologie basse température (traces de fission sur apatites, TFA) avec une analyse structurale détaillée pour décrire les mouvements verticaux associés à l'évolution du système chevauchant, et pour déterminer l'influence de ce dernier sur le cycle sédimentation/enfouissement/exhumation des dépôts synorogéniques du bassin d'avant-chaine sud (bassins de Jaca et Ainsa). L'analyse TFA complète les données déjà publiées dans la Zone Axiale et la Zone Nord-Pyrénéenne, et constitue la première étude de ce genre dans un bassin d'avant-chaîne pyrénéen. Les données TFA sur la transversale du bassin sud-pyrénéen montrent une diminution vers le sud du degré d'effacement des traces de fission, traduisant la diminution vers le sud de la quantité d'enfouissement, supérieure à 5 km au nord et inférieure à 3 km au sud dans l'hypothèse un géotherme de 25°.km-1. Le contexte géologique montre que l'enfouissement est principalement lié à l'accumulation des dépôts synorogéniques. Les données TFA de la partie nord du bassin montrent un refroidissement d'âge Oligocène supérieur-Miocène inferieur (moyen). Par ailleurs, une nouvelle interprétation de profils de sismiques réflexion dans le bassin de Jaca montre que le chevauchement d'Oturia s'enracine dans le chevauchement de socle de Bielsa, responsable de l'exhumation tectonique hors-séquence du bord sud de la Zone Axiale au Miocène inférieur (-moyen) (Jolivet et al., 2007). Ces résultats attestent donc de l'exhumation tectonique hors-séquence au Miocène inférieur (Burdigalien- ?Langhien) de la partie nord du bassin d'avant-chaine sud-pyrénéen. Des données TFA obtenues dans la Zone Axiale et la Zone Nord-Pyrénéenne confirment la migration générale vers le sud du système chevauchant, et mettent également en évidence la réactivation tectonique hors-séquence du bord nord de la Zone Axiale à l'Oligocène terminal-Miocène inférieur. L'ensemble de ces résultats atteste donc de la réactivation en « pop-up » de la parties interne des Pyrénées centre-ouest à l'Oligocène supérieur-Miocène inférieur (Burdigalien- ?Langhien), postérieurement au scellement du front sud-pyrénéen (Aquitanien- ?Burdigalien) classiquement considéré comme marquant la fin de la compression pyrénéenne. Ces données nous ont permis de proposer un nouveau modèle d'évolution crustale des Pyrénées centro-occidentales en 3 grandes étapes : (i) du Crétacé supérieur à l'Eocène moyen, le prisme est caractérisé par une absence de relief, en lien avec l'inversion de structures extensives crétacées conduisant à l'accrétion de petites écailles crustales ; (ii) la période Eocène supérieur-Oligocène correspond à la collision continentale proprement dite, et est marquée par la création d'importants reliefs associés à l'accrétion d'épaisses unités crustales ; (iii) au Miocène inférieur, la partie interne du prisme pyrénéen est réactivée. / In this work on a complete transect of the west-central Pyrenees, we combine low temperature thermochronology (apatite fission tracks, AFT) with a detailed structural analysis to describe vertical movements related to the thrusting system evolution, and to determine the influence of the latter on the sedimentation/burial/exhumation cycle of the synorogenic deposits of the southern foreland basin (Jaca and Ainsa basins). AFT analysis from a transect of the south-Pyrenean basin show the southward decrease of the fission track reset level from the southern edge of the Axial Zone to the South-Pyrenean frontal thrust, implying the southwards decrease of the burial amount from more than 5km in the north to less than 3km in the south assuming an average geothermal gradient of 25°C.km-1. The structural setting of the Jaca basin attests that the burial of the synorogenic sediments was mainly due to the sedimentary accumulation. AFT data from the northern part of the basin display a late Oligocene-early (middle) Miocene cooling event. New interpretation of industrial seismic reflection profiles across the Jaca basin suggests that the Oturia thrust is rooted in the Bielsa basement thrust, responsible for the early (-middle) Miocene out-of-sequence tectonic reactivation of the southern flank of the Axial Zone (Jolivet et al., 2007). These results reveal a lower Miocene (Burdigalian -?Langhian) out-of-sequence episode of tectonic activity of the interior of the south-Pyrenean foreland basin. AFT data from the Axial Zone and the North-Pyrenean Zone confirm the general southward migration of the thrusting system, and also bring evidence of the late Oligocene-lower Miocene out-of-sequence tectonic reactivation of the northern flank of the Axial Zone. All these results attest of a late Oligocene-lower Miocene (Burdigalian-?Langhian) 'pop-up' reactivation of the inner part of the west-central Pyrenees, younger than the sealing of the south-Pyrenean front (Aquitanian-?Burdigalian) which is classically considered to mark the end of the Pyrenean compression. These results lead us to propose a new crustal scale evolution model of the west-central Pyrenees in 3 stages: (i) From the Late Cretaceous to the middle Eocene, the orogenic prism is characterised by the absence of relief, related to the inversion of Cretaceous extensional structures leading to the accretion of thin crustal units; (ii) The late Eocene-Oligocene stage corresponds to the continental collision, marke d by the creation of important relief associated with the accretion of thick crustal units; (iii) During the early Miocene, the inner part of the Pyrenean wedge is tectonically reactivated.