published_or_final_version / abstract / toc / China Area Studies / Master / Master of Arts

Objets très communs dans l’aire de culture tibétaine, les tsha tsha, fabriqués à l’aide de moules, sont des images en argile figurant des stūpa, des divinités bouddhiques, des personnages historiques, ainsi que des inscriptions. Leur fabrication est avant tout considérée comme une pratique religieuse visant à générer des mérites mais aussi à purifier les actions négatives. Réalisés en masse, ils constituent des témoignages fidèles et mésestimés des développements iconographiques et stylistiques qui ont marqués l’art bouddhique tibétain au fil des siècles. En l’absence d’études antérieures, un travail de recensement systématique des matériaux relatifs aux tsha tsha a fait apparaître une richesse documentaire insoupçonnée susceptible d’éclairer non seulement l’histoire de l’art tibétain, mais également certains aspects relevant de l’anthropologie religieuse, de la philologie, ou encore de la paléographie. Dans le cadre de notre thèse, nous avons privilégié une démarche globalisante prenant en considération l’ensemble des données disponibles en procédant conjointement à l’étude d’un très large corpus de pièces sélectionnées, à celle de la littérature afférente, et aux observations de terrain. Dans cette perspective, nous avons envisagé l’étude des tsha tsha sous divers angles: l’origine et l’histoire de la diffusion de cette pratique au Tibet, la terminologie relative à ces objets, les techniques de fabrication, les usages, l’iconographie, les styles et enfin les inscriptions présentes à leur surface ou introduites. Cette approche nous a permis de révéler finement l’ampleur et les développements que cette pratique bouddhique d’origine indienne a connu dans le monde tibétain. / Very commonplace in the Tibetan world, tsha tshas are clay impressions produced from a mould depicting, either in relief or moulded in the round, stūpas, Buddhist deities, historical figures and inscriptions. Making them is essentially considered to be a religious practice intended to generate and accumulate merit but also to purify negative deeds and obscurations. Produced in mass and generally preserved inside sealed edifices, tsha tshas are true yet underrated evidence of the iconographic and stylistic developments that have marked Tibetan Buddhist art over the centuries. In the absence of any previous studies, the task of establishing a systematic inventory of sources related to tsha tshas revealed an unsuspected wealth of material for elucidating not only the history of Tibetan art, but also some aspects of religious anthropology, philology, or paleography. In this doctoral research, we favored a globalizing approach that takes into account all the available data by studying a very large corpus of selected pieces, of the literature related to the tsha tshas, as well as field observations. In this context, we considered the study of tsha tshas from different angles: the origin and history of how this practice spread through Tibet, the terminology for these objects, the techniques for making them, their uses, iconography, styles and finally the inscriptions that are found on their surface or inside them. This approach has allowed us to explain more accurately the true extent of this Buddhist practice of Indian origin and the developments it has undergone in the Tibetan world since its introduction in about the 8th-9th centuries to the present day.

Quand et comment le Plateau Tibétain s'est édifié demeure une question complexe, aux nombreuses implications pour la compréhension du comportement des lithosphères continentales en collision. Certains modèles mettent en avant l'importance du sous-plaquage de la lithosphère indienne et d'un épaississement localisé aux limites de micro-plaques asiatiques rigides ; tandis que d'autres considèrent au contraire que la lithosphère asiatique est peu résistante et se déforme de manière distribuée. La base croissante de données de haute qualité documentant les processus de surface et les processus profonds doit à présent être intégrée afin de contraindre les différents modèles d'évolution du Plateau. Ce travail de thèse se concentre sur le nord-est du bloc du Qiangtang, au Tibet Central : alors qu'elle constitue un élément clé pour les reconstructions et les modèles, cette région demeure l'une des moins étudiées de la zone de collision. Dans une première partie, l'acquisition de nouveaux âges 40Ar/39Ar de la déformation tardi-triasique (215-200 Ma) sur la suture de Jinsha, ainsi que la datation et l'étude métamorphique de xénolites crustales à corindon d'âge Trias Inférieur (249 Ma) échantillonnées dans des laves éocènes, mettent en évidence le rôle majeur et sous-estimé des subductions mésozoïques dans l'épaississement crustal total. Les résultats suggèrent que la région avait atteint, avant le début de l'Éocène, une épaisseur crustale de l'ordre de 45 à 55 km, soit près de 80% de son épaisseur actuelle de 66 km. Cet épaississement crustal mésozoique fut probablement en grande partie la conséquence du magmatisme d'arc du NE-Qiangtang, lié à 80 Ma de subductions océaniques à ses bordures. Ces nterprétations sont cohérentes avec les données régionales d'émersion et de paléoaltitude entre le Trias et l'Éocène. Dans une seconde partie, l'étude pétrologique et géochimique de roches magmatiques d'âge Éocène des bassins de Xialaxiu et de Nangqian suggère un intense métasomatisme du manteau lithosphérique source par des fluides ou magmas riches en H2O et en CO2. Ces résultats servent de point de départ à une série de modèles rhéologiques et thermomécaniques visant à caractériser le comportement d'une telle lithosphère dans un contexte de convergence continentale. Nous montrons que le manteau lithosphérique sous notre région d'étude à l'Éocène était à la fois très peu résistant (logmin~2.3), très peu dense (~3310 kg/m3 à 2 GPa), et possédait un solidus fortement défléchi vers les basses températures aux moyennes pressions mantelliques (~930°C à 3 GPa). À partir de ces caractéristiques, les modèles thermo-mécaniques laissent envisager un régime atypique de déformation et de fusion partielle, par l'injection de manteau lithosphérique métasomatisé dans l'asthénosphère sous-jacente. Celui-ci reproduit correctement l'intervalle de temps et la distance entre les épisodes magmatiques de Xialaxiu et de Nangqian, ainsi que la magnitude de l'épaississement crustal dans notre région d'étude, sans impliquer de délamination de la racine lithosphérique adoucie. Ces résultats nous amènent à proposer un réexamen des données géophysiques disponibles sur le manteau lithosphérique tibétain, dans lequel la zone de faibles vitesses sismiques imagée à l'aplomb du Tibet Central pourrait être interprétée en terme d'anomalie chimique et minéralogique, et non d'anomalie thermique. / How and when the Tibetan Plateau was built remains a complicated issue, with many implications for our understanding of the behaviour of colliding continental lithospheres. Some models highlight the importance of the underthrusting of the Indian lithosphere and of localized thickening at the edges of rigid Asian microplates ; while others consider that the Asian lithosphere is weak and deforms in a distributed manner. The growing, high-quality database documenting deep and surface processes has now to be integrated in order to constrain the different evolution models of the Plateau.This thesis work focuses on the north-eastern Qiangtang block in Central Tibet : although it is a keystone for reconstructions and models, this region remains one of the least studied of the collision zone.In a first part, new 40Ar/39Ar dating of the Late Triassic (215-200 Ma) deformation on the Jinsha suture, along with a metamorphic study of Early Triassic (249 Ma) corundum-bearing crustal xenoliths sampled in Eocene magmatic rocks, shed light on the the major, but underestimated role played by the Mesozoic subductions in bulk crustal thickening. Our results suggest that prior to the Eocene, our study area had reached a crustal thickness of 45-55 km, i.e 80% of its present-day crustal thickness of 66 km. This Mesozoic crustal thickening was likely achieved by continental arc magmatism related to the 80 Ma of continuous oceanic subductions on both edges of the NE-Qiangtang terrane.These interpretations are consistent with the regional emersion and paleo-altitude data.In a second part, a petrological and geochemical study of Eocene magmatic rocksfrom the Nangqian and Xialaxiu basins suggests an intense metasomatism of the source lithospheric mantle by H2O- and CO2-rich fluids or melts. These results are used as a starting point for a series of rheological and thermo-mechanical models, to characterize the behaviour of such lithosphere in a continental convergence context. We show that the lithospheric mantle underlying our study area in the Eocene was particularly weak (logmin~2.3) and buoyant (~3310 kg/m3 à 2 GPa), and its solidus was deflected to low temperatures at medium mantle pressures (~930°C à 3 GPa). From these characteristics, thermo-mechanical models forecast an atypical deformational and partial melting regime, through the injection of metasomatized lithospheric mantle into the asthenosphere, whichadequately reproduces the timing and location of Xialaxiu and Nangqian magmatic events, and the magnitude of crustal thickening observed in our study area, without any delamination of the weakened lithospheric root.This eventually leads us to reconsider the available geophysical data for the Tibetan lithospheric mantle : the low-velocity zone imaged beneath Central Tibet could indeed represent a geochemical, rather than thermal anomaly.

Metamorphic rocks constitute a vast volumetric proportion of the Earth’s continental lithosphere and are invaluable recorders of the mechanisms and rates of deformation and metamorphism that occur at the micro-, meso- and macro-scale. As such, they have the potential to provide detailed insight into important tectonic processes such as the subductive transport of material into, and back from, mantle depths and also folding, faulting and thickening of crust that occurs during collisional orogeny. The Himalayan-Karakoram-Tibetan orogen is the youngest and most prominent example of a continent-continent collisional mountain belt on Earth today and is a product of the on-going convergence of the Indian and Asian plates that initiated in the Early Eocene. Thus, it provides an exceptional natural laboratory for the investigation of such processes. Recent advances in the computational ability to replicate natural mineral assemblages through a variety of metamorphic modelling techniques have led to improvements in the amount (and quality) of petrographic data that may be obtained from a typical metamorphic rock. In this study, phase equilibria modelling (pseudosection construction) using THERMOCALC, amongst other techniques, has been integrated with in-situ U–Pb and Th–Pb geochronology of accessory monazite in order to constrain the tectonothermal evolution of four regions intimately associated with the Himalayan-Karakoram-Tibetan orogen. These regions comprise the Karakoram metamorphic complex (north Pakistan), the Tso Morari massif (north-west India), the eastern Himalayan syntaxis (south-east Tibet) and the Day Nui Con Voi metamorphic core complex of the Red River shear zone (North Vietnam). Each case study documents previously unreported metamorphic, magmatic or deformational events that are associated with the India-Asia collision. These data have allowed original interpretations to be made regarding the tectonic evolution of each individual region as well as the large-scale evolution of the Himalayan-Karakoram-Tibetan orogenic system as a whole.

published_or_final_version / abstract / Earth Sciences / Master / Master of Philosophy

published_or_final_version / Education / Doctoral / Doctor of Philosophy

published_or_final_version / Chinese Language and Literature / Master / Master of Arts

published_or_final_version / Earth Sciences / Master / Master of Philosophy

No description available.

Policy-makers, project planners and development organisations are becoming convinced that the failure of the new socio-ecologically sensitive strategies co-opted by 'professional' forestry could be better addressed by indigenous forestry. They believe that indigenous forestry might assist with the development of successful forestry projects that are ecologically sustainable and socio-politically equitable. In order, however, to learn from indigenous forestry systems, the acculturation of foresters in the vernacular culture of the forest users appears to be an essential process for understanding and intervening in a local forest management complex. Acculturation entails not only more attention to the immaterial cultural realm, but an understanding of multiple resource stewardship, local ways of knowing and perceiving, local forest values and 'practices of care'. While acknowledging the significance of the politics of knowledge and political ecology this study examines resource stewardship from an alternative neglected angle that of knowledge sustainability and synergistic bridging. It will examine in general modes of knowing and bridging between 'formal' and indigenous forestry knowledge, and in particular the identification of forest value paradigms that are evidently exemplars of bio-cultural sustainability. The main outcomes of this study include the cognitive mapping of forest values among 'Tibetan minority nationalities' in Eastern Kham, their spatial distribution and the coincidence of changes in forest values with cultural or biophysical phenomena. Conceptually this study relies heavily on knowledge-system, hypertext, and paradigm theory and a critique of the narratives of John Locke. The former provide a platform to compare and contrast alternative knowledge systems and a means of synergistic bridging between them and the latter encapsulates a trajectory of western knowledge often known as modernity. The quantitative methods employed in this study included text analysis for forest value identification, multidimensional scaling for the cognitive mapping of forest values, spatial analysis and kriging for forest value distribution, and boundary or wombling analysis for changes in forest values and their coincidence with cultural or biophysical phenomena. The latter four methods are groundbreaking in that they have never been used to study forest values before. The study concludes that there is compelling evidence suggesting homogeneity in forest values with up to 5 geospatial paradigms and up to 12 cognitive paradigms. The findings, especially close correlation between forest values and ethnolinguistics, provide a potential template for foresters to develop multiple models of natural resource or biodiversity stewardship based on local forest values. In terms of the wider application, indigenous knowledge cannot seemingly be sustained if it is integrated with or into western knowledge systems due to the lack of conceptual frameworks for cross-cultural epistemological or psychological integration. Coalescing under the rubric of post-modernism, however, we do find a number of complimentary trajectories, which seemingly provide space for knowledge equity, sustainability and bridging. These trajectories include hypertext theory, paradigm theory, abductive logic, adaptive management, ecospiritual paradigms, and post-modern forestry paradigms. These trajectories and findings offer planners globally a means for synergistic bridging between local and non-local knowledge systems on the road to sustainable forestry and biodiversity stewardship.