The Himalayan orogen provides a natural laboratory to test models of orogenic development due to large-scale continental collision. The Greater Himalayan Series (GHS), a lithotectonic unit continuous along the entire length of the belt, comprises the metamorphic core of the Himalayan orogen and underlies the highest topography. GHS rocks are exposed as a moderately north-dipping slab bounded below by the Main Central Thrust (MCT) and above by the South Tibetan Detachment System (STDS) of normal faults. Coeval reverse- and normal-sense motion on the crustal-scale MCT and STDS ductile shear zones allows the GHS to be modeled as an extruded wedge or channel of mid-crustal material. Due to this unique tectonic setting, the deformation path of rocks within the bounding shear zones and throughout the core of the GHS profoundly influences the efficiency of extrusion and exhumation processes. Attempts to quantify GHS deformation and metamorphic evolution have provided significant insight into Himalayan orogenic development, but these structural and petrologic studies are often conducted in isolation. Penetrative deformation fabrics developed under mid-upper amphibolite facies conditions within the GHS argue that deformation and metamorphism were coupled, and this should be considered in studies aimed at quantifying GHS teconometamorphic evolution. This work focuses on two projects related to the coupled deformation, thermal and metamorphic evolution during extrusion and exhumation of the GHS, focused on the lower and upper margins of the slab. A detailed examination of the P--T history of a schist collected from within the MCT zone of the Sutlej River, NW India, provides insight into the path experienced by these rocks as they traveled through the crust in response to the extreme shortening related to India-Asia collision. Combined forward thermodynamic and diffusion modeling indicates compositional zoning preserved in garnet has remained unmodified since growth and can be related directly to the P--T--X evolution of rocks from this zone. Classic porphyroblast--matrix relationships coupled with the above models provide a structural framework within which to interpret the microstructures and provide additional constraints on the relative timing of metamorphic and deformation events. A combined microstructural and quartz petrofabric study of rocks from the highest structural levels of the GHS in the Zanskar region was completed. This work provides the first quantitative estimate of temperatures attending normal-sense shearing along the Zanskar Shear Zone, the westernmost strand of the STDS. Results indicate penetrative top-N (extensional) deformation occurred at elevated temperatures and resulted in the telescoping of isothermal surfaces present during shearing and extrusion of GHS rocks. Simple geometric models invoking heterogeneous simple shear parallel to the overlying detachment require dip-slip displacement magnitudes on the order of 15--40 km, identical to estimates derived from nearby barometric analyses. Finally, focus is given to the rotational behavior of rigid inclusions suspended in a flowing viscous matrix from a theoretical perspective. Predictions of clast rotational behavior have been used to construct several kinematic vorticity estimation techniques that have become widely adopted for quantitative studies of naturally deformed rocks. Despite the popularity of the techniques, however, basic questions regarding clast-based analyses remain open. Therefore a numerical model was constructed and a systematic investigation of 2- and 3D clasts suspended in steady and non-steady plane-strain flows was undertaken to determine likely sources of error and the intrinsic strengths and limitations of the techniques. / Ph. D.

Mineral chemistry and thermobarometry of mafic pods in the Liverpool Land Eclogite Terrane (LLET) provide insight into potential relationships with regional high-pressure (HP) and ultrahigh-pressure (UHP) terranes such as the North East Greenland Eclogite Province (NEGEP), the Western Gneiss Region (WGR), and HP granulites in the East Greenland Caledonides at Payer Land. Grt-cpx thermometry and jadeite barometry performed on garnet and omphacite cores in a sequence of retrogressed eclogites give minimum and average P-T values across six samples for eclogite at 18.4 ± 3.7 kbar at 764 ± 156 °C. Granulite facies conditions based on early retrograde Opx-Plag symplectites, garnet rim compositions, and relict omphacite grains give P-T values at 12.7 ± 0.6 kbar at 860 ± 10 °C, based on grt-cpx thermometry and the opx-grt-pl-qtz equilibra. Late retrograde amphibolite facies conditions, marked by matrix plagioclase and biotite and orthopyroxene symplectite replacement by hornblende symplectites, give mean P-T values of 6.8 ± 0.4 kbar at 740 ± 150 °C, based on grt-cpx thermometry and the grt-hbl-plag-qtz equilibra. Thermometers and barometers yield a qualitative P-T path from lower eclogite facies pressures through the granulite facies via hot isothermal and static decompression, preserving symplectite textures, to amphibolite facies conditions via isobaric cooling. The path is consistent with low-pressure WGR eclogites and suggests affinities between the LLET and Baltica.

Cette thèse est centrée sur la ceinture orogénique Attico-Cycladique formée durant l'orogénèse Alpine. Par une approche multi-méthodes et multi-échelles combinant géologie structurale, pétrographie, thermobarométrie des assemblages minéraux, géochimie élémentaire et isotopique, et données PVTX des inclusions fluides associées, ce travail vise à caractériser et comprendre les relations entre circulations fluides, interactions fluides/roches, déformation, et mobilisation-transport-dépôt des métaux. Les marbres et schistes de la péninsule du Lavrion et de l'île d'Eubée témoignent d'une évolution orogénique complexe marquée par une phase d'enfouissement à l'Eocène suivie par deux phases d'exhumation successives syn-et post-orogéniques. Les minéralisations de type Cu-Pb-Zn-Fe-Ag de la région du Lavrion sont synchrones de l’activation du détachement post-orogénique et de la mise en place de plutons de granodiorite. Leurs positions structurales témoignent d’un piégeage depuis un régime de déformation ductile jusqu'à fragile. Les minéralisations mises en place durant le régime de déformation ductile à ductile-fragile (skarn et remplacement de carbonate) sont associées à la décarbonatation des niveaux de marbres et à la circulation des fluides magmatiques. L'exhumation progressive de la racine orogénique se traduit par la transition des roches depuis une déformation ductile vers un régime fragile associé à l’ouverture du système aux fluides de surface et notamment aux fluides météoriques. Cette circulation est responsable d’une remobilisation des métaux des minéralisations primaires permettant alors une seconde phase de précipitation dans un régime cassant (veines épithermales) / This thesis is focused on the Attico-Cycladic orogenic wedge formed during the Alpine orogeny. From a multi-method and multi-scale approach using structural geology, petrography, mineral thermobarometry, element and isotope geochemistry, and PVTX data of associated fluid inclusions, this study deciphers the relationships between fluid circulation, fluid-rock interactions and mobilisation-transport-deposits of metals. Marbles and schists from the Evia Island and the Lavrion peninsula testify to a complex orogenic history marked by an Eocene burial phase followed by syn- and post-orogenic exhumation. Cu-Pb-Zn-Fe-Ag mineralisations from the Lavrion area are synchronous with the formation of the low-angle post-orogenic detachment and the emplacement of granodioritic magmas. The structural position of the deposits attests of an emplacement during ductile to brittle deformation conditions. Deposits associated with ductile to ductile-brittle deformation (skarn, carbonate replacement) are related to a marble decarbonation and magmatic fluid circulation. The progressive exhumation of the orogenic wedge allows the transition toward brittle conditions and opens the system to surficial meteoritic fluids. This meteoritic fluid circulation is responsible to remobilisation of metals from primary deposits allowing thus a second phase of deposition in a pure brittle deformation (epithermal veins)