Mid-ocean ridge hydrothermal systems are known to extend to deep levels of the oceanic crust, including the plutonic section, but little is known about the timing and nature of fluid-rock interactions at these levels. To investigate the temporal and spatial characteristics of hydrothermal alteration in the lower crust, this study investigates a suite of hydrothermally altered (<5 to >20% hydrous alteration) gabbroic rocks recovered from the Hess Deep Rift, where 1.2 Ma fast-spreading East Pacific Rise crust is well-exposed. These samples were altered to amphibole-dominated assemblages with chlorite-rich samples occurring in a restricted region of the field area. Hornfels, indicative of reheated, previously altered rocks, are clustered in the central part of the field area. The entire sample suite has elevated 87Sr/86Sr (mean: 0.70257±0.00007 (2σ), n=16) with respect to fresh rock (0.7024). Bulk rock 87Sr/86Sr is strongly correlated with percentage of hydrous alteration and weakly correlated with bulk rock Sr content. The distribution of Sr in igneous and metamorphic minerals suggests that greenshist-facies alteration assemblages (chlorite, actinolitic amphibole, albitic plagioclase) lose Sr to the fluid while amphibolite-facies secondary assemblages (secondary hornblende, anorthitic plagioclase) take up Sr. The temperature-dependent mobilization of Sr in hydrothermal systems has implications for the 87Sr/86Sr and ultimately fluid/rock ratio calculations based on the assessed 87Sr/86Sr systematics. Considering Sr behaviour, minimum fluid/rock ratios of ~1 were calculated for the plutonic section. Due to the large uncertainty regarding fluid Sr composition at depth and the sensitivity of fluid/rock ratio calculations on this parameter, a model combining the sheeted dike complex and the plutonic section to one hydrothermal system is introduced, yielding a fluid/rock ratio of 0.5. This value may be more realistic since the fluid composition entering and exiting the sheeted dike complex is better constrained. The regional distribution of hornfelsed material with elevated 87Sr/86Sr suggests that fluid ingress into the upper plutonics at Hess Deep occurred on-axis in a dynamic interface of a vertically migrating axial magma chamber (AMC) and the base of the hydrothermal system. / Graduate

Despite increasing concern about the presence of heavy metals, pesticides and other toxins in indoor environments, very little is known about the physical and chemical composition of ordinary household dust. This study represents the first systematic investigation of the mineralogical composition of indoor dust in residential housing in Canada. Specimens of dust were obtained from homes in six geographically separate cities in the Province of Ontario: two located on the metamorphic and igneous rocks of the Precambrian Canadian Shield (Thunder Bay and Sudbury), the other four located on Palaeozoic limestone and shale dominated bedrock (Barrie, Burlington, Cambridge, and Hamilton). Forty samples of household vacuum dust were obtained. The coarse fraction (80 – 300 µm) of this dust was subjected to flotation (using water) to separate the organic components (e.g. insect fragments, dander), natural and synthetic materials (e.g. fibres, plastics) from the mineral residue. The mineral fraction was then analyzed using quantitative point counting, polarizing light microscopy, powder X-ray diffraction and scanning electron microscopy methods. Despite the great distances between the sampling localities and the distinct differences in bedrock geology, the mineral fraction of dust from all six cities is remarkably similar and dominated by quartz and feldspar, followed by lithic fragments, calcite, and amphibole. Some evidence of the influence of local geology can nevertheless be found. For example, a relatively higher proportion of sulphide minerals is observed in the two cities on the Canadian Shield where these minerals are clearly more abundant in the bedrock. Specimens from Sudbury, Canada’s largest mining centre located atop a nickel-sulphide mineral deposit, showed the highest sulphide contents. Quartz is the dominant mineral in all cities. All quartz grains have internal strain features and fluid inclusions that are indicative of a metamorphic-igneous provenance. In all cities, sand is used on the streets as an abrasive for traction during the icy winter season. This sand is obtained in all cases from local glaciofluvial deposits that were ultimately derived principally from the rocks of the Canadian Shield in the last Pleistocene glaciations that affected all of Ontario. Thus, tracking in sand is the most plausible mechanism by which quartz was introduced into these homes since sampling was done, in all cases, in the winter season. The results indicate that glacial deposits dominate the mineral composition of indoor dust in Ontario cities and that nature of the bedrock immediately underlying the sampling sites is relatively of minor importance.

The Chachahuén volcanic complex, with the Cerro Bayo laccolith as one of the largest intrusions, is part of back-arc Payenia volcanic province in western central Argentina. Laccoliths show potential for generating oil in sedimentary basins and producing ore deposits. It is crucial to put more effort into understanding the magma plumbing system beneath the Chachahuén volcanic complex, which the Cerro Bayo laccolith is part of. Thus this project present the first thermobarometric modelling for the Cerro Bayo laccolith and the Chachahuén volcanic complex. Several thermometers and barometers were applied to plagioclase, amphibole and clinopyroxene to understand magma evolution in the underlying plumbing system. The dacitic to rhyodacitic laccolith rocks from Cerro Bayo have porphyric textures with plagioclase in the form of both clots (glomerocrysts) and single crystals, amphibole and clinopyroxene as main phenocrysts, while enclaves are more mafic in composition and have equigranular textures. Plagioclase in the sample varies from andesine to labradorite with a composition of An22-An68, while the clinopyroxene can be classified into diopside to augite with cores (Mg#=76-84) and rims (Mg#62-72). Amphibole, varies from pargasite, ferropargasite to magesiohastingsite and hastingsite, which can be grouped into three groups according to the Mg#: low Mg# amphibole (Mg# = 40-51), medium Mg# amphibole (Mg# = 52-61) and high Mg# amphibole (Mg# = 62-78). Besides, most of the Fe-Ti oxides in the samples are titanomagnetite with Usp mol.% in the range of 0.04-0.54. Results from clinopyroxene-liquid thermobarometers suggest a crystallization depth of 44 to 51 km for clinopyroxene cores and a crystallization depth of 19 to 31 km for rims, of which the derived crystallization temperatures are in the range of 1144 to 1170 °C and 973 to 1002 °C respectively. On the other hand, different thermobarometers of amphibole give consistent results of crystallization temperatures and depths. According to the amphibole-liquid thermometer, low Mg# (Mg#= 40-51) amphiboles have the lowest crystallization temperature in the range of 898 to 931°C, while medium Mg# (Mg#=52-61) amphiboles have higher crystallization temperatures in the range of 951 to 972°C and high Mg# (Mg# = 62-78) amphiboles have highest crystallization temperatures between 991 and 1013°C. The depth translated from pressure derived from amphibole-liquid barometers give a shallower crystallization depth range from 19 to 30 km for low Mg# amphiboles, a deeper crystallization depth in the range of 22 to 39 km for high Mg# amphiboles and deepest crystallization depth range of 27 to 41 km for medium Mg# amphiboles. Moreover, a depth from 2 to 20 km could be gained from the plagioclase-liquid thermobarometry which crystallized at 883 to 910°C. It is worth to point out that crystallization depth of clinopyroxene cores is deeper than the Moho in the Chachahuén area, while crystallization depth and temperatures of clinopyroxene rims are consistent with those of high Mg# amphiboles. Consistent temperatures and depths are also found for crystallization of plagioclase and low Mg# amphiboles which intergrow with each other. Thus, a multi-level magma plumbing system began from below the Moho, with a mushy zone in the upper crust, could be suggested to exist beneath the Cerro Bayo laccolith. Evidence from both petrology and geochemistry also indicate fractional crystallization as well as processes of magma mixing and recharge during magma evolution. / Chachahuén火山综合体，包含其最大的侵入体Cerro Bayo岩盘，是位于阿根廷中西部Payenia弧后火山区的一部分。前人研究多着重于岩石学、地球化学和地层学方面，因而针对下伏岩浆涌升系统的研究在该地区极具前瞻性，需要投入更多工作。本文首次尝试对Chachahuén火山复合体应用温压计进行研究，针对斜长石、角闪石和单斜辉石应用了不同的温度计和压力计，以揭示下伏于Cerro Bayo岩盘的岩浆涌升系统中的岩浆演化。 来自Chachahuén火山复合体Cerro Bayo岩盘的英安质-流纹英安质火成岩具有板状-似斑状结构，其斑晶主要为单晶或聚合物形式存在的斜长石、角闪石及单斜辉石。此外，岩盘中还发现具等粒结构的酸性捕虏体的存在。样品中斜长石（An=22-68）主要成分为中长石至拉长石.单斜辉石主要为透辉石和普通辉石，常发育高镁值核部（Mg#=76-84）和低镁值环带（Mg#62-72）。角闪石主要为韭闪石、铁韭闪石、镁绿钙闪石和绿钙闪石，可根据镁值进一步划分为三个组：低镁值组（Mg# = 40-51），低镁值组（Mg# = 52-61）和高镁值组（Mg# = 62-71）。此外，样品中的钛铁氧化物重要为钛磁铁矿（Usp%=0.04-0.54）。 单斜辉石-熔体温压计的结果表明单斜辉石的核部和环带的结晶温度和深度有所差异：核部具有较高的结晶温度（1144-1170 °C）和较深的结晶深度（44-50km），而环带具有较低的结晶温度（973-1002 °C）和较浅的结晶深度（18-31 km）。与角闪石相关的不同温压计给出了类似的结晶温度和压力，其中存在的微小差异均在误差范围内。因此本文将角闪石-熔体温压计的结果作为最终结果，其显示低镁值角闪石具有较低结晶温度（898-931°C），中镁值角闪石具较高结晶温度（951-972°C），而髙镁值角闪石具最高结晶温度（991-1013°C）。角闪石的结晶深度特征有所不同：低镁值角闪石的结晶深度最浅（19-30km），髙镁值角闪石的结晶深度较深（22-39 km），反而中镁值角闪石结晶深度最深（27-41 km）。斜长石-熔体温压计给出的斜长石结晶温度和深度分别为883-910°C及1-20km。 值得一提的是单斜辉石核部的结晶深度位于研究区莫霍面之下。同时，单斜辉石的环带与髙镁值角闪石具有相似的结晶温度和深度，而斜长石及共生的低镁值角闪石具有相似的结晶温度。因此可以推测，Cerro Bayo岩盘之下，发育一个自莫霍面之下开始的多层岩浆上涌系统。而岩石学和地球化学的证据还表明在岩浆发育过程中岩浆分化结晶和岩浆重注和混合作用并存。 / En lakkolit är en grund magmaficka och en vanligt förekommande del av en vulkan, vilken kan bilda en länk mellan djupa magmatiska aktiviteter och vulkanutbrott. Forskning om kompositionen och bildandet av grunda magmafickor kan hjälpa till att öka förståelsen om geologiska faror och naturresurser. Vid Cerro Bayo exponeras en grund magmakammare vilken utgör en del av Chachahuén vulkankomplexet i Argentina. Det här projektet fokuserar på det magmatiska lagringssystemet och magmautvecklingen vid Cerro Bayo. Magmasammansättningen och magmakammarens förhållanden såsom tryck, temperatur och vattenhalt samt vattensystemets struktur är viktiga faktorer som styr magmatiska processer. För att förstå magmautvecklingen under Cerro Bayo inleddes projektet med en kompositionsanalys av bergprover och mineral. Därefter genomfördes termobarometrisk modellering för att bestämma temperatur- och tryckförhållandena för kristalliseringen av mineraler i det magmatiska systemet. Resultaten av modelleringen tyder på att ett magmatiskt rörsystem av flera nivåer existerar under Cerro Bayo lakkoliten. Det djupaste magmamagasinet ligger på 44-50 km och når upp till 22-41 km i nedre jordskorpan, medan de grunda reservoarerna av magma ligger på ett djup av 2-20 km i övre jordskorpan som slutligen når den grunda magmafickan. Vidare indikerar analysen av mineralstruktur och mineralkemi processer av fraktionerad kristallisering samt påfyllning och blandning av magma under magmautvecklingen. Magman genomgick fraktionerad kristallisering under rörelser uppåt från de djupaste magmakammarna. Magmans temperatur varierar från högre än 1100 ° C till ~ 900 ° C. Ansamlingar av magma fortsatte att fylla på magmamagasin i nedre och övre jordskorpan. Blandning av magma inträffade när en ansamling varmare magma rörde sig från nedre till övre jordskorpreservoarer och påverkade såväl migrering av magma som placeringen av Cerro Bayo lakkoliten

Despite increasing concern about the presence of heavy metals, pesticides and other toxins in indoor environments, very little is known about the physical and chemical composition of ordinary household dust. This study represents the first systematic investigation of the mineralogical composition of indoor dust in residential housing in Canada. Specimens of dust were obtained from homes in six geographically separate cities in the Province of Ontario: two located on the metamorphic and igneous rocks of the Precambrian Canadian Shield (Thunder Bay and Sudbury), the other four located on Palaeozoic limestone and shale dominated bedrock (Barrie, Burlington, Cambridge, and Hamilton). Forty samples of household vacuum dust were obtained. The coarse fraction (80 – 300 µm) of this dust was subjected to flotation (using water) to separate the organic components (e.g. insect fragments, dander), natural and synthetic materials (e.g. fibres, plastics) from the mineral residue. The mineral fraction was then analyzed using quantitative point counting, polarizing light microscopy, powder X-ray diffraction and scanning electron microscopy methods. Despite the great distances between the sampling localities and the distinct differences in bedrock geology, the mineral fraction of dust from all six cities is remarkably similar and dominated by quartz and feldspar, followed by lithic fragments, calcite, and amphibole. Some evidence of the influence of local geology can nevertheless be found. For example, a relatively higher proportion of sulphide minerals is observed in the two cities on the Canadian Shield where these minerals are clearly more abundant in the bedrock. Specimens from Sudbury, Canada’s largest mining centre located atop a nickel-sulphide mineral deposit, showed the highest sulphide contents. Quartz is the dominant mineral in all cities. All quartz grains have internal strain features and fluid inclusions that are indicative of a metamorphic-igneous provenance. In all cities, sand is used on the streets as an abrasive for traction during the icy winter season. This sand is obtained in all cases from local glaciofluvial deposits that were ultimately derived principally from the rocks of the Canadian Shield in the last Pleistocene glaciations that affected all of Ontario. Thus, tracking in sand is the most plausible mechanism by which quartz was introduced into these homes since sampling was done, in all cases, in the winter season. The results indicate that glacial deposits dominate the mineral composition of indoor dust in Ontario cities and that nature of the bedrock immediately underlying the sampling sites is relatively of minor importance.

La vaste distribution géographique et la longue durée du magmatisme au Mésozoïque supérieur (Jurassique et Crétacé) en Chine du Sud présente le cas unique dans le monde. Ceci présente un laboratoire naturel très favorable a l’étude des processus de magmatogénèse, et des modes de mise place des plutons granitiques. Il permet également d’aborder l’analyse des relations magmatisme-tectonique et les contextes géodynamiques de la mise en place de magma dans leur cadre lithosphérique. Depuis les années 50, et surtout les années 90, des scientifiques ont mis un effort important sur la cartographie géologique, mené des études pétrologiques et géochronologiques et ainsi obtenu une base solide pour la compréhension de l’évolution tectonique du Bloc de Chine du Sud (SCB). Cependant, des questions fondamentales restent encore sans réponses ou vivement débattues. Dans le but de progresser sur ces sujets fondamentaux, nous avons mené des études pluridisciplinaires sur les massifs d’âge Mésozoïque supérieur de Qingyang-Jiuhua (Province d’Anhui), Hengshan (Province de Hunan) et certains plutons affleurant dans la zone côtière du Fujian. Le choix des massifs est fonde sur leur distance variable par rapport à la paléozone de subduction, les âges comparables de ces massifs et les déformations associées. Les méthodes d’étude comprennent l’observation de terrain, l’analyse microscopique de lames minces, la datation par U-Pb de monazite, l’ASM, le paléomagnétisme, la modélisation gravimétrique et la barométrie à partir de Al-total dans l’amphibole magmatique. Bien que chaque massif présente des caractéristiques distinctes, ils partagent des points communs du point de vue de leur orientation préférentielle, de la déformation de leurs encaissants et de l’influence de la tectonique régionale sur leur mise en place, D’après nos nouveaux résultats et en intégrant les données précédentes, nous discutons dans cette thèse les contextes tectoniques de mise en place de ces massifs granitiques et l’évolution géodynamique de SCB, et proposons un scénario géodynamique en 3 étapes. (1) Pendant la période 145-130 Ma, la subduction vers le NW de la plaque Paléo-Pacifique sous le continent asiatique fait rapprocher le micro-continent de l’Ouest-Philippines avec le continent de Chine du Sud, produisant l’important magmatisme d’arc et formant un régime tectonique en extension en SCB ? Dans l’arrière-arc; (2) Pendant la période 130-110 Ma, dûe à la collision entre le micro-continent de l’Ouest Philippines et SCB, une structure compressive vers le NW a été développée dans la zone de Changle Nan’ao, produisant des déformations ductiles. Cependant, l’intérieur de la partie orientale du SCB était encore en régime tectonique extensif de direction NW-SE; (3) Pendant la période 105-90Ma, une nouvelle zone de subduction a été développée au SE du micro-continent de l’Ouest Philippines, le panneau subductant atteint la zone de Changle-Nan’ao, avec probablement des morceaux de panneau cassé, provocant l’ascension de l’asthénosphère, responsable de la mise en place d’importants massifs granitiques et de filons. La tectonique de SCB pendant cette période est caractérisée par un système tectonique d’extension générale. Ce dispositif a été significativement perturbe par l’ouverture oligo-miocène de la mer de Chine du Sud et par la compression miocène de la marge à Taiwan. Ce modèle géodynamique reste à être amélioré par de futures investigations géologiques, géophysiques et géochimiques. / The vast distribution and long duration of the Late Mesozoic magmatism in the eastern part of South China presents a unique case in the world. This offers a natural laboratory to study the process of magma genesis, the magma emplacement mode, the relationship between magmatism and tectonics, the geodynamic role on the magma emplacement and lithospheric evolution. Since 50’s, particularly 90’s of the last century, geoscientists have made important efforts in geological cartography and carried out numerous studies with remarkable scientific achievements, building a solid background to understand the tectonic evolution of the South China Block (SCB). However, certain fundamental questions mentioned above remain unsolved and/or are in hot debate. In order to make progress in these scientific issues, we have carried out in a multi-disciplinary study in the Late Mesozoic Qingyang-Jiuhua massif, Hengshan massif and Fujian coastal zone according to their distance with respect to the paleo subduction zone of the Paleo-Pacific plate, the ages of granitic massifs and related tectonics, including field observation on the structure geology, micro-observation on thin section, U-Pb dating on monazite, AMS, paleomagnetism, gravity modeling and P condition concern the granite emplacement. In the view of deformation in these granitic massifs and their country rocks, mode and influence of regional tectonics on the emplacement, though each studied zone reveals its distinguished characteristics, they show some intrinsic and common relationships between them. With our new results and integrating previous data, in this thesis, we discuss the tectonic context of emplacement of these Late Mesozoic magmatic massifs and the geodynamic evolution of the SCB., We propose a 3-step geodynamic model: (1) during 145-130 Ma period, the Paleo-Pacific plate subducted northwestwardly, the West Philippines micro-continent, approaching to SCB, important subduction-related arc volcanism was produced in the coastal areas of Southeast China coast (Zhejiang-Fujian-Guangdong), forming a back-arc extension tectonic system in SCB; (2) during 130-110 Ma period, due to the collision between the West Philippines microcontinent and SCB, the compressional tectonic structures were developed in the Changle-Na’ao coastal zone, producing ductile deformation zones. However, the inland of the eastern part of SCB was under a NW-SE extensional tectonic regime; (3) during 105-90 Ma period, a new subduction zone was developed in the SE flank of the West Philippines micro-continent, the subducting slab reached the Changle-Nan’ao tectonic belt, with the possible break-off of slab, the asthenospheric ascent was responsible for the important emplacement of plutonic massifs and dykes. The tectonics of the eastern part of SCB was characterized by a general extensional system in this period. This tectonic pattern has been significantly disturbed by the Oligocene-Eocene opening of the South China sea,and the Miocene shortening of the SCB margin in Taiwan. Of course, this model should be improved by more geological, geophysical and geochemical investigations.