Agência Nacional do Petróleo / Na região de Lauro Müller, sul de Santa Catarina, a presença de óleo nos arenitos das formações Rio Bonito e Palermo foi observada em diversos poços e nas galerias de uma das minas da Carbonífera Catarinense. Amostras desse óleo foram submetidas às análises de isótopos estáveis de carbono e cromatografia gasosa espectrometria de massas visando, a princípio, identificar a sua origem. O óleo apresentou feições moleculares típicas de ambiente anóxico hipersalino, sendo correlacionado ao Membro Assistência da Formação Irati. Parâmetros moleculares revelaram que o mesmo foi gerado durante o pico de geração de hidrocarbonetos e encontra-se leve a moderadamente biodegradado. A comparação entre o óleo catarinense e os arenitos asfálticos de Anhembi (SP) revelou diferenças moleculares relacionadas à fácies orgânica, grau de evolução térmica e biodegradação. A geração do óleo no sul catarinense está intimamente relacionada ao efeito térmico das intrusões ígneas cretácicas sobre os intervalos geradores da Formação Irati, haja vista que a unidade encontra-se termicamente imatura na maior parte da bacia. O óleo teria migrado lateralmente da Formação Irati para os arenitos reservatório da Formação Rio Bonito através de falhas com rejeitos verticais superiores a 150 m, as quais foram identificadas em mapas e seções geológicas. Também foram realizadas análises de pirólise, isótopos de carbono e de biomarcadores em amostras da Formação Irati no poço CAT 204, realizado pela Carbonífera Catarinense, a fim de avaliar o efeito térmico de duas soleiras de diabásio intrudidas no Membro Assistência. Foi observado um aumento dos valores de δ13C em direção ao contato com as intrusivas e a completa senilização da unidade. O halo termal abaixo da soleira inferior se estendeu, pelo menos, até a base da Formação Irati, situada a uma distância de 1,4 vezes a espessura do corpo intrusivo. Amostras da parte inferior da Formação Palermo, coletadas no poço CAT 204, e das três principais camadas de carvão do sul catarinense, coletadas nas minas da Carbonífera Catarinense, também se encontram termicamente maturas, sugerindo a proximidade de outros corpos intrusivos. Dessa forma, conclui-se que deve ter havido um aquecimento generalizado dos sedimentos no sul de Santa Catarina causado pela grande incidência de soleiras na região. / In the region of Lauro Müller, south of Santa Catarina, the presence of oil in sandstones of Rio Bonito and Palermo formations were observed in several wells and in the galleries of a coal mine. Samples of oil were subjected to stable carbon isotopes and gas chromatography mass spectrometry analysis to identify its origin. The oil had typical features of a hypersaline anoxic environment, achieving a positive correlation with Assistência Member of Irati Formation. Molecular parameters revealed that it was generated during the peak of hydrocarbon generation and is light to moderately biodegraded. The comparison between oil encountered in Lauro Müller and the tar sands of Anhembi (SP) revealed molecular differences related to organic facies, level of biodegradation and thermal maturity. The generation of oil in southern Santa Catarina is closely related to the thermal effect of igneous intrusions in the source rocks of Irati formation, given that the unit is thermally immature in most of the basin. The oil would have migrated laterally from Irati Formation to the reservoir sandstones of Rio Bonito Formation through faults with vertical slips over 150 m, identified on maps and geological sections. Pyrolysis, stable carbons isotopes and biomarkers analysis was also performed in a local section of Irati Formation to evaluate the heating effect of two dolerite sills intruded into Assistência Member. It was observed an increase in δ13C toward the intrusive contacts and that Assistência Member was completely overmature. The thermal halo below the lower sill reached, at least, the bottom of the Irati Formation, located at a distance of 1.4 times the thickness of the intrusive body. Samples from the lower portion of Palermo Formation, collected in the well CAT 204, and the three main coal layers from southern Santa Catarina, collected in Carbonífera Catarinenses mines, are also thermally mature, suggesting the proximity of other intrusive bodies. Thus, it is concluded that there was a general heating of the sediments of southern Santa Catarina caused by the high incidence of igneous intrusions in the region.

Agência Nacional do Petróleo / Na região de Lauro Müller, sul de Santa Catarina, a presença de óleo nos arenitos das formações Rio Bonito e Palermo foi observada em diversos poços e nas galerias de uma das minas da Carbonífera Catarinense. Amostras desse óleo foram submetidas às análises de isótopos estáveis de carbono e cromatografia gasosa espectrometria de massas visando, a princípio, identificar a sua origem. O óleo apresentou feições moleculares típicas de ambiente anóxico hipersalino, sendo correlacionado ao Membro Assistência da Formação Irati. Parâmetros moleculares revelaram que o mesmo foi gerado durante o pico de geração de hidrocarbonetos e encontra-se leve a moderadamente biodegradado. A comparação entre o óleo catarinense e os arenitos asfálticos de Anhembi (SP) revelou diferenças moleculares relacionadas à fácies orgânica, grau de evolução térmica e biodegradação. A geração do óleo no sul catarinense está intimamente relacionada ao efeito térmico das intrusões ígneas cretácicas sobre os intervalos geradores da Formação Irati, haja vista que a unidade encontra-se termicamente imatura na maior parte da bacia. O óleo teria migrado lateralmente da Formação Irati para os arenitos reservatório da Formação Rio Bonito através de falhas com rejeitos verticais superiores a 150 m, as quais foram identificadas em mapas e seções geológicas. Também foram realizadas análises de pirólise, isótopos de carbono e de biomarcadores em amostras da Formação Irati no poço CAT 204, realizado pela Carbonífera Catarinense, a fim de avaliar o efeito térmico de duas soleiras de diabásio intrudidas no Membro Assistência. Foi observado um aumento dos valores de δ13C em direção ao contato com as intrusivas e a completa senilização da unidade. O halo termal abaixo da soleira inferior se estendeu, pelo menos, até a base da Formação Irati, situada a uma distância de 1,4 vezes a espessura do corpo intrusivo. Amostras da parte inferior da Formação Palermo, coletadas no poço CAT 204, e das três principais camadas de carvão do sul catarinense, coletadas nas minas da Carbonífera Catarinense, também se encontram termicamente maturas, sugerindo a proximidade de outros corpos intrusivos. Dessa forma, conclui-se que deve ter havido um aquecimento generalizado dos sedimentos no sul de Santa Catarina causado pela grande incidência de soleiras na região. / In the region of Lauro Müller, south of Santa Catarina, the presence of oil in sandstones of Rio Bonito and Palermo formations were observed in several wells and in the galleries of a coal mine. Samples of oil were subjected to stable carbon isotopes and gas chromatography mass spectrometry analysis to identify its origin. The oil had typical features of a hypersaline anoxic environment, achieving a positive correlation with Assistência Member of Irati Formation. Molecular parameters revealed that it was generated during the peak of hydrocarbon generation and is light to moderately biodegraded. The comparison between oil encountered in Lauro Müller and the tar sands of Anhembi (SP) revealed molecular differences related to organic facies, level of biodegradation and thermal maturity. The generation of oil in southern Santa Catarina is closely related to the thermal effect of igneous intrusions in the source rocks of Irati formation, given that the unit is thermally immature in most of the basin. The oil would have migrated laterally from Irati Formation to the reservoir sandstones of Rio Bonito Formation through faults with vertical slips over 150 m, identified on maps and geological sections. Pyrolysis, stable carbons isotopes and biomarkers analysis was also performed in a local section of Irati Formation to evaluate the heating effect of two dolerite sills intruded into Assistência Member. It was observed an increase in δ13C toward the intrusive contacts and that Assistência Member was completely overmature. The thermal halo below the lower sill reached, at least, the bottom of the Irati Formation, located at a distance of 1.4 times the thickness of the intrusive body. Samples from the lower portion of Palermo Formation, collected in the well CAT 204, and the three main coal layers from southern Santa Catarina, collected in Carbonífera Catarinenses mines, are also thermally mature, suggesting the proximity of other intrusive bodies. Thus, it is concluded that there was a general heating of the sediments of southern Santa Catarina caused by the high incidence of igneous intrusions in the region.

Lead isotope compositions have been obtained from five major volcanic and intrusive rock suites and several ore deposits on Vancouver Island. Lead, uranium and thorium concentrations and strontium isotope ratios have been obtained for a subset of these samples. The rock suites examined are the Paleozoic Sicker Group, Triassic Karmutsen Formation, Jurassic Island Intrusions and Bonanza Group volcanic rocks, and the Eocene Catface intrusions. Isotope geochemistry of the Sicker Group is consistent with the interpretation that it formed as an island arc. Relatively high 207pb/204pb ratios indicate sediment involvement in the subduction process, which suggests that the Sicker Group formed close to a continent. Buttle Lake ore deposits display decreasingly radiogenic lead isotope ratios with time, suggesting that the associated magmas become increasingly primitive. This supports the hypothesis that these deposits formed during the establishment of rifting in a back-arc environment. Karmutsen Formation flood basalts display isotopic mixing between an ocean island-type mantle source and average crust. Isotopic evidence is used to support a Northern Hemisphere origin for these basalts. Mixing is apparent in the lead and strontium isotope signatures of the Island Intrusions and Bonanza Group volcanic rocks, between depleted mantle and crustal (possibly trench sediments) components. This is consistent with formation of these rocks in an island arc environment. Eocene Catface intrusions have relatively high 207pb/204pb indicating that crustal material was involved in their formation. There are two groups of plutons corresponding to an east belt and west belt classification. Galena from the Zeballos mining camp related to the Eocene Zeballos pluton indicates that the mineralization was derived from the pluton. Galena lead isotope data from Vancouver Island may be interpreted in a general way by comparison with data from deposits elsewhere of known age and origin. No single growth curve model can be applied. Lead isotope characteristics of Vancouver Island are clearly different from those of the North American craton, reflecting the oceanic affinities of this terrane. A new technique has been developed to compare 207pb/204pb ratios between samples with differing 206pb/204pb ratios. The procedure projects 207pb/204pb ratios along suitable isochrons until they intersect a reference value of 206pb/204pb. This technique can be used for interpreting lead isotope data from old terranes, in which lead and uranium may have undergone loss or gain, and if lead and uranium abundances have not been measured. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Denna rapport undersöker grundvattenmagasin på öar i Stockholms skärgård och hur de förväntas påverkas av klimatförändringarna. Främst granskas grundvattnets kvantitet och kvalitet fram till år 2100 utifrån två olika klimatscenarion framtagna av FN:s klimatpanel. Detta kopplas sedan till hur boende på ön kan komma att påverkas av dessa förändringar samt hur de kan hantera de problem som förväntas uppstå. Vidare undersöks kommuners roll samt lösningar de kan bidra med. Ämnet kopplar till det svenska miljömålet ”Grundvatten av god kvalitet” som betonar vikten av kunskap om dagens grundvattenstånd i utsatta områden, till vilka kustnära regioner tillhör.  För att besvara frågorna som ställts i rapporten har bland annat litteraturstudie, fältstudie, intervjuer, modelleringar av månadsvisa grundvattenstånd samt beräkningar av risk för saltvatteninträngning i brunnar tillämpats. Fältstudien gjordes på Aspö, en typisk skärgårdsö i Stockholm, för vilken sedan all modellering och beräkningar utförts på. Aspö fungerar därför i denna rapport som modell för Stockholms skärgårdsöar.  I modelleringar och beräkningar har aspekter som vattenanvändning, geologi, nederbörd, evapotranspiration och växtperiodens längd beaktats. Resultatet från modelleringarna tyder på stora risker för sinande grundvattenmagasin på skärgårdsöar under sommarmånaderna, både i dagsläget och i framtiden. Under sommaren är grundvattenbildningen liten till obefintlig och vattenanvändningen som störst, på grund av den stora mängd sommarboende i skärgården, vilket kan leda till vattenbrist och vattenkvalitetsproblem. På grund av en förlängd växtperiod som hämmar grundvattenbildningen förväntas dessa problem bli värre i framtiden. Vad gäller beräkningarna av saltvatteninträngning är det brunnar i strandnära lägen som löper störst risk. Eftersom en höjning av havsnivån förväntas till följd av ökad medeltemperatur, förväntas risken för saltvatteninträngning öka än mer i framtiden.  Både modelleringarna och beräkningarna tyder på att en sparsam vattenanvändning gör situationen mindre ansträngd. Utöver detta föreslås att kommunen utvidgar kartläggningen av riskområden med hjälp av lagstöd för att ta över delar av ansvaret som idag främst vilar på fastighetsägaren för den enskilda vattentäkten. / This thesis examines groundwater reservoirs of islands in the Stockholm archipelago and  how they will be affected by climate change. Mainly the quality and quantity of reservoirs in the year 2100 are looked at based on two different climate scenarios developed by IPCC (Intergovernmental Panel on Climate Change). That gets connected to how the inhabitants on the islands will be affected by the changes and how they can deal with the potential problems that arises. Furthermore, the municipalities’ roles will be examined along with the solutions they can contribute with regarding water shortage. The subject of the thesis also connects to the Swedish environmental goal “Good-Quality Groundwater” which puts an emphasis on the importance of knowledge regarding groundwater levels in exposed areas such as coastal regions.  To answer the questions posed in the thesis, methods such as literature review, field study, interviews, modeling of monthly groundwater level and calculations of the risk of saltwater intrusions in wells have been applied. The field study was done on the island Aspö, a typical archipelago island in Stockholm, for which all the modelling and calculations later have been made. Thus, Aspö acts as a model of Stockholm’s archipelago islands in this thesis.  In the modelling and calculations factors like water usage, geology, precipitation, evapotranspiration, and the length of the growing season have been considered. The results of the groundwater modelling indicate a great risk of diminishing groundwater reservoirs on archipelago islands during the summer months, both now and in the future. In the summer the groundwater recharge is little to nonexistent and the water usage at its peak, due to the large quantity of summer occupants in the archipelago, which can lead to a water shortage and problems with the water quality. Because of a prolonged growing season that disturbs the groundwater recharge, these issues are expected to become worse in the future. When it comes to the calculations of the saltwater intrusions in wells, the wells closest to the coasts are at a greater risk. Since an increase in the sea level are to be expected due to a rise in global temperature the risk for saltwater intrusion also increases.  Both the modelling and the calculations indicates that a sparing water usage will make the situation less strained. In addition, it’s suggested that the municipalities should expand their mapping of sensitive areas through legal support to shoulder some of the responsibility that today rests on property owners of the individual water supply.

Cone-sheet swarms are magmatic sheet intrusions and part of volcanic plumbing systems and are pathways for magma to the Earth’s surface, where they feed volcanic eruptions. The analysis of cone-sheets provides information on the geometry of the magmatic plumbing system of a volcano and allows to understand processes and dynamics of magma transport. This is important to interpret information during a volcanic crisis and to help reduce risks to humans and infrastructure. In order to create a realistic model, the structure and shape of cone-sheet complexes can be reconstructed in three-dimensional space. Most cone-sheet swarms are not sufficiently exposed to allow such a reconstruction. The Tejeda cone-sheet swarm on Gran Canaria (Canary Islands, Spain), however, is an excellent location to study a cone-sheet complex in great detail, as it is exposed over 15 kmhorizontally and 1000 m vertically. This allows to determine its geometry in 3D space. The felsic deposits of the Miocene Tejeda caldera were intruded by cone-sheets between 11.7 and 7.3 Ma. Schirnick et al. (1999) assumed straight cone-sheets, based on 2D projections, and suggested that the Tejeda cone-sheet swarm is formed by a stack of uniformly dipping, parallel intrusive sheets that converge towards a common, static, laccolith-like source, forming a concentric structure around acentral axis that has the geometry of a truncated cone. This hypothesis was tested in this study, using structural data from Schirnick (1996) as well as additional data collected in the field. Using the software Move™, the extensive data set was visualized and projected in three dimensional space. The underlying magmatic source of the cone-sheets was reconstructed using two different approaches, with the first one based on sets of cross-sections to select intersection points, following an approach prognosed by Burchardt et al. (2013a). To improve the quality of the reconstruction of the magma chamber, a second method was developed using geometric calculations in MATLAB. The results indicate that individual cone-sheets are straight with parallel to slightly fanning dips, which can be steeper in the central part of the cone-sheet complex. They converge towards a common centre, creating a sub-spherical geometry of the source of the cone-sheet complex. Comparison of the two approaches used for the magma chamber reconstruction indicate that the second approach (geometric calculations) produces less uncertainties in data interpretation. The modelling results lead to the proposition of a dynamic model for the emplacement of the Tejeda cone-sheet complex. Cone-sheets would start to intrude from a reservoir situated at about 4500m below sea level that became successively shallower with time. / Inverterade koniska intrusionssvärmar är en del av det underjordiska vulkaniska systemet som möjliggör vägar för magma till jordens yta, där de livnär vulkaniska utbrott. Genom analys av inverterade koniska intrusioner kan information om geometrin hos magmatiska system erhållas vilket gör det möjligt att förstå magmans processer och transportdynamik. Detta är viktigt då det hjälper att tolka information under vulkaniska kriser och kan bidra till att minska risker för människor och infrastruktur. För att skapa en realistisk modell, kan strukturer och former av komplexa inverterade koniska intrusionssvärmar rekonstrueras i ett tredimensionellt utrymme. De flesta inverterade koniska intrusionssvärmar är inte tillräckligt blottade på jordens yta för att möjliggöra en sådan rekonstruktion.Tejedas inverterade koniska intrusionssvärm på Gran Canaria (Kanarieöarna, Spanien) är dock utmärktbelägen för att studera ett inverterat koniskt intrusionskomplex i detalj, detta då den är blottad i över 15 km horisontell och 1000 m i vertikal utsträckning. Detta gör det möjligt att bestämma dess geometrii tre dimensioner. De felsiska avlagringarna av den Miocena Tejeda kalderan blev intruderade av inverterade koniskaintrusioner mellan 11,7 och 7,3 Ma. Schirnick et al. (1999) antog att dessa intrusioner var raka, baseratpå 2D-projektioner, och föreslog att Tejedas inverterade koniska intrusionssvärm bildades som enlikformigt stupande stapel av parallella intruderande plan som konvergerar mot en gemensam, statiskoch lakkolitisk källa, vilken i sin tur bildar en koncentrisk struktur runt en central axel med samma geometri som en inverterad stympad kon. Denna hypotes undersöktes i detta arbete, med hjälp avstrukturell data från Schirnick (1996) samt ytterligare data insamlat från fält. Den omfattande datamängden visualiserades och projicerades i tre dimensioner med hjälp av mjukvaran Move™. Denunderliggande magmatiska källan till det inverterade koniska intrusionskomplexet rekonstruerades medhjälp av två olika metoder, den första är baserad på tvärsnitt där planens skärningspunkter kan studeras, följt av ett tillvägagångssätt framställt av Burchardt et al. (2013a). För att förbättra kvalitén pårekonstruktionen av magmakammaren utvecklades en andra metod med hjälp av geometriskaberäkningar i MATLAB. Resultaten tyder på att enskilda inverterade koniska intrusioner är raka med parallellt till svagt flacktstupning, vilka kan vara brantare mot den centrala delen av komplexet. De konvergerar mot ettgemensamt centrum, vilket skapar en sub-sfärisk geometri hos källan till det inverterade koniskaintrusionskomplexet. Jämförelse av de två metoderna som används för magmakammarens rekonstruktion tyder på att denandra metoden (geometriska beräkningar) ger färre osäkerheter i tolkningen. Modelleringsresultatettyder på en dynamisk modell för bildningen av Tejedas inverterade koniska intrusionskomplex. Enligtdessa resultat skulle de inverterade koniska intrusionerna till en början ha utgått från en reservoarungefär 4500 m under havsytan som med tiden förflyttade sig mot grundare nivåer.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Le Massif composite du Tichka a été étudié dans le but de préciser les mécanismes de sa formation, pour les raisons suivantes : il offre une coupe verticale de 2500m avec une qualité exceptionnelle d'affleurements qui permet de faire des observations et des échantillonnages en continu ; il montre une gamme de composition allant des gabbros aux leucogranites avec des relations spectaculaires entre les diorites et les granitoïdes contemporains. Les études de terrain, pétrographiques, minéralogiques, géochimiques, isotopiques (Sr et Nd) ont été utilisées pour mieux cerner sa genèse. De plus, l'étude des structures magmatiques et des propriétés rhéologiques des magmas a permis de mieux comprendre le mode d'ascension et de mise place du pluton. Le modèle génétique ainsi proposé peut être appliqué à d'autres associations plutoniques comparables, d'âges et d'environnements géotectoniques variés. Le Massif du Tichka s'est mis en place il y a 291 ± 5 Ma (isochrone Rb-Sr sur roches totales) dans des séries cambriennes au Nord de l'accident du Tizi n'Test (N70), branche de la faille Sud-Atlasique. La profondeur de cette mise en place a été estimée, par barométrie sur les amphiboles des plutonites, à 7 km environ, en accord (1) avec les estimations des épaisseurs de la pile sédimentaire encaissante et (2) avec les conditions thermobarométriques de développement des minéraux, par métamorphisme de contact, à proximité immédiate du pluton. Sur l'ensemble du massif, cinq groupes de roches ont été identifiés sur la base de critères de terrain, pétrographiques et géochimiques : gabbros, diorites (subdivisées en méladiorites, diorites communes et diorites hétérogènes), granodiorites-tonalites, monzogranites, leucogranites (subdivisés en leucogranites à biotite ± amphibole et leucogranites à deux micas). Toutes ces roches, mis à part les leucogranites à deux micas plus jeunes, sont contemporaines. L'étude des structures acquises' à l'état magmatique montre que: (1) le complexe est constitué de trois intrusions composites, à géométrie bien définie, sub - contemporaines, limitées au Sud par des écrans d'encaissant méta-volcanosédimentaire, et d'une intrusion de leucogranites à deux micas, localisée dans le Nord-Est, légèrement plus tardive et à géométrie mal définie; (2) la source magmatique a migré au cours du temps du Sud-Ouest vers le Nord-Est; (3) le mouvement de la composante décrochante dextre de l'accident du Tizi n'Test était -relativement faible par rapport à la composante inverse au moment de la mise en place; (4) les parties internes du massif montaient plus vite que, les parties externes lors de l'ascension des intrusions; (5) l'intrusion de leucogranites à deux micas, la plus récente, est constituée de petits corps diapiriques rassemblés autour du diapir kilométrique du Tasghimout; elle s'est mise en place alors que les autres intrusions étaient déjà cristallisées mais pas entièrement refroidies. Les études pétrographiques, minéralogiques, géochimiques, isotopiques (Sr et Nd) ont permis de proposer le type de genèse suivant: deux magmas basiques issus du manteau sous-continental par des taux de fusion différents, se mettent en place successivement en base de croûte. Le premier cristallise rapidement en évoluant peu et pratiquement sans contamination; il donnera le groupe des gabbros. Le second est soumis à un processus complexe qui allie cristallisation fractionnée et contamination (AFC) par la croûte. Il formera le groupe des diorites. La montée de ces magmas et de l'anomalie thermique qui les accompagne induit la fusion de la base de la croûte de nature hétérogène et litée. Cette croûte a été injectée de magmas basiques à intermédiaires peu de temps avant sa fusion. Son anatexie génère des magmas de composition granodioritique et monzogranitique. Le magma monzogranitique évolue par cristallisation fractionnée jusqu'à des leucogranites à biotite ± amphibole. Les magmas dioritique et granodioritique sont rassemblés à la profondeur de 15 à 20 km dans une chambre magmatique où une stratification est obtenue par convection et instabilité gravitaire et où des échanges entre les magmas, qui commencent à cristalliser, ont probablement eu lieu mais de façon limitée. Les leucogranites à deux micas qui forment l'essentiel de l'intrusion Nord-Est sont des granites de type S formés par anatexie de la croûte supérieure. Ils se mettent en place tardivement alors que le bâti avait un comportement cassant. La fin de l'activité magmatique est marquée par une activité hydrothermale localisée et par la mise en place de filons doléritiques. Le Massif du Tichka est de type calédonien post collision; les roches basiques qui le composent ont des caractères de basaltes intraplaques continentales plus précisément transitionnels et les granitoïdes ont des traits de granites post-collision. L'association du Tichka est de, type cafémique métalumineuse, transitionnelle à tendance suba1caline sodique. Les leucogranites à deux micas appartiennent au domaine alumino-potassique. Les calculs des densités et des viscosités des magmas montrent que (1) leur montée a pu se faire sous forme diapirique, (2) le magma dioritique a une viscosité plus faible (104 poises) que le magma granodioritique (106 poises) et (3) les viscosités peuvent s'inverser au cours de la cristallisation vers des températures de 850°C. L'évolution des viscosités au cours du refroidissement et l'inversion de leur courbe, permettent d'expliquer toutes les figures observées aux interfaces entre les diorites et les granodiorites synchrones. L'accident du Tizi n'Test (de direction N70) et, dans une moindre mesure, la zone faillée ouest-atlasique (subméridienne), à proximité desquels le Massif du Tichka s'est mis en place, ont joué un rôle important dans la genèse du pluton. Le premier a permis, en effet, par décompression adiabatique et introduction d'eau, la fusion du manteau et a facilité la montée des magmas basiques. Cette genèse est intracontinentale dans un bloc émergé (ou presque) depuis le Tournaisien ; elle se déroulerait dans cette période charnière entre la collision (épaississement) continentale carbonifère et la distension permienne. Par son histoire complexe impliquant des intrusions emboîtées multiples, des sources magmatiques nombreuses, des processus de genèse variés, le Massif du Tichka présente des affinités avec d'autres massifs hercyniens au Maroc ou ailleurs dans la chaîne varisque ouest européenne.

C'est a l'échelle de la turbulence que se produit l'entraînement d'air sec du flux d'Harmattan a l'intérieur du flux humide de Mousson. Ce processus de petite échelle est analysé dans le cadre du programme AMMA (Analyse Multidisciplinaires de la Mousson Africaine) qui vise a mieux renseigner et prévoir la mousson de l'Afrique de l'ouest. Les mesures atmosphériques réalisées par l'avion de recherche français ATR-42 et la modélisation des grands tourbillons (LES) sont complémentaires et permettent de documenter la structure verticale, moyenne et turbulente de la couche limite Sahélienne, de d'écrire les intrusions d'air sec et leur contribution dans les transferts turbulents, de quantifier le processus d'entraînement, de tester les paramétrisations existantes et de les relier aux conditions de grande échelle, et aux caractéristiques de la couche limite et de ses interfaces, notamment du cisaillement de vent Mousson/Harmattan.

We develop a two dimensional model that simulates the response of the crust to prolonged mantle-derived intrusions in arc environments. The domain includes the entire crustal section and upper mantle and focuses on the evolving thermal structure due to intrusions and external tectonic forcing. We monitor the thermal response, melt fraction and volume for different environments after a definite time by considering geologically relevant melt flux and extensional tectonic rates. The amount of crustal melt versus fractionated primary mantle melts present in the crustal column helps determine crustal structure and growth through time. We observe that with a geophysically estimated flux and tectonic rate, the mantle-derived magma bodies can melt the surrounding volume of crust. We express the amount of crustal melting in terms of an efficiency; therefore we define the melting efficiency as the ratio of the melted volume of crustal material to the volume of melt expected from a strict enthalpy balance as explained by Dufek and Bergantz (2005). Melting efficiencies are less than 1.0 in real systems because heat diffuses to sections of the crust that never melt. The maximum calculated efficiency is 0.05 in our model while most of our simulations show zero efficiency. Additionally, maximum total melt amount is observed in relatively greater extensional environments (0.02 m/yr) and high intrusion rates (10⁻² m³/m²/yr) and in long time periods (2 x 10⁶ years). However, maximum crustal melting in the same environment is reached in 1.2 x 10⁶ years. The relative amounts of mantle-derived and crustal melts in the total volume of magma suggest that the majority of magma composition in crustal column is derived from the mantle material.

The sheeted complex of the ~92 Ma Tenpeak pluton, in the Northern Washington Cascades crystalline core, forms a <1.5-km wide zone with a moderate, NE-dip at the SW margin of the pluton. Sheeted magmatic complexes, such as the one in the Tenpeak pluton, are common in plutons and represent examples of incremental growth of plutons. Though it is widely accepted that plutons are constructed incrementally over prolonged timescales of several million years, it is not clear if and to what degree individual batches of magma interact, the timing and size of each magma pulse, and the role, timing, and location of magmatic differentiation. This project uses a combination of field evidence, bulk rock chemistry, and mineral geochemistry to address the (1) role of magma mixing and fractionation, (2) constraints on the relative timing of magma differentiation, (3) diversity of mixing styles preserved, and (4) physical properties that dictate how individual batches of magma interact within this sheeted complex. Rock samples were collected throughout the complex from mafic, felsic, dioritic, thinly-banded, and gradational sheets. Field evidence shows a range of sheet contacts that vary from sharp to diffuse, strong prevalence of mafic enclaves, and localized cases of mechanical mixing in which plagioclase feldspars from a felsic sheet are incorporated into a mafic sheet. In general, sheet thickness increases farther from the contact with the White River shear zone. The bulk rock and mineral chemistry suggests that the felsic magmas in sheets formed independently from the more mafic and hybridized sheets. The composition of the felsic sheets cannot be modeling by binary mixing processes involving mafic and felsic magmas or result from fractionating the most mafic magmas. However, mass-balance calculations using a linear least-squares mass balance calculation and Rayleigh fractionation models indicate that it is possible to explain the range of felsic compositions by internal, crystal fractionation driven mostly by plagioclase crystallization (~40-58%). Negative Eu anomalies in amphiboles from the felsic sheets imply that plagioclase fractionation commenced prior to the onset of amphibole crystallization. With the exception of the most primitive mafic sheet sampled, the mafic and hybridized sheets represent variable proportions of the mafic parental magma and the range of felsic differentiated magmas. Efficient mixing that resulted in these mafic to hybridized magmas must also have occurred prior to mineral growth as the mineral chemistry reflects intermediate, mixed compositions. The bulk rock and mineral chemistry of the most primitive, mafic sheet suggest that it did not mix with any felsic magmas. However there is evidence that the mafic sheet underwent plagioclase fractionation prior to emplacement. This is evident by lower bulk rock Sr/Ba relative to calculated Sr/Bamelt of plagioclase that cannot be reconciled without removing ~40-58% plagioclase. In contrast to the felsic sheets, the amphiboles from this mafic sheet lack Eu anomalies implying that amphibole crystallization occurred prior to major plagioclase fractionation. Chemical evidence reveals that magma mixing played an important role in controlling the chemical composition of individual sheets and field observations suggesting that there was a range of mixing styles. Throughout the sheeted complex, there are localized sites of mechanical mixing where plagioclase phenocrysts from adjacent felsic sheets are mechanically mixed into mafic sheets. Evidence for mechanical mixing is present across both sharp and gradational contacts. This implies varying rheological and viscosity contrasts between different sheets, though in both cases crystallinity and viscosity appears sufficiently low to allow crystals to migrate across sheet contacts. Variability in sheet thickness and contact type suggests that the physical parameters (i.e. temperature, viscosity, rheology, and magma flux) of the system continue to evolve throughout the formation of the sheeted complex. Near the White River, sheets are thin and more heterogeneous but become progressively thicker (>302 m) and more felsic in composition up-section. The composition of plagioclase and amphibole is remarkably uniform in all of the felsic sheets suggesting that each sheet formed from an array of felsic parental magmas. Thicker, felsic sheets most likely reflect hotter conditions where larger magma fluxes could be accommodated or viscosity-temperature contrasts that were low enough to allow for efficient mixing between two adjacent sheets and therefore erase sheet contacts. / Graduation Date: 2013