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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Interaction Between Different Magma Types in the Reyðarártindur Magma Chamber, SE Iceland / Interaktion mellan olika magmatyper i magmakammaren Reyðarártindur, sydöstra Island

Rousku, Sabine January 2019 (has links)
Southeast Iceland exhibits a granophyre pluton called Reyðarártindur, which has never been described in detail before. The Reyðarártindur magma chamber formed 7.30 ± 0.06 Ma ago (Padilla, 2015). Glacial and coastal erosion expose the pluton, and a river cuts through the pluton roof and walls, revealing interaction between different blob-like structures of magma. The formation of magma chambers can take a very long time, it is therefore likely for several different magmas to interact. Incremental formation of different magma batches give rise to mixing and mingling in magma chambers. To understand when the magma mixing was initiated and the mechanisms controlling it, descriptive analysis were made to obtain textural properties of collected rock samples from the field. The purpose for this thesis study was to examine if there is a frequency size and shape distribution of the magma blobs and if the different magma blobs are systematically distributed across the river. Previous studies have inferred conduit locations and magma mixing processes through similar methods. Extensive field studies have provided all samples for this thesis. Five distinct, magma types were described and found to be interacting. There was one ‘host magma’ which the other four different magma types are exposed as ‘blobs’ within. The statistical analysis involved mapping the blob-like structures from photos taken with an Unmanned Aerial System (URA; drone), using the software Inkscape. The data and measurements for the blobs was collected and summarized in ImageJ. The data was then statistically analyzed in Excel, illustrating the frequency of the magma blob’s size and shape distribution in selected parts of the river. The results of the statistical analysis of the magma blobs showed that ~80 % of the blobs existed in a size interval between 0 – 0.1 m2 . This thesis provides a discussion about the implications of the blob distributions for magma chamber recharge and processes within this section of the magma chamber. The shape distribution analysis showed an indication for all the blobs to be more rounded and equant. This suggest that the magma mixing event probably happened at the same time, during a liquid phase. / På sydöstra Island återfinns en granofyrisk pluton kallad Reyðarártindur. Det är en magmakammare som aldrig tidigare blivit beskriven i detalj. Magmakammaren bildades för 7,30 ± 0,06 Ma sedan (Padilla, 2015). Plutonen har blivit exponerad genom glacial- och fluvial erosion samt att en flod skär igenom plutonens tak och väggar. Den eroderande floden exponerar olika fläckliknande strukturer av magmainteraktioner. Ett gradvist bildande av olika magmasatser har över lång tid gett upphov till en blandning i magmakammaren. För att förstå när magmablandningen initierades och mekanismerna bakom fenomenet, har en beskrivande analys gjorts för att ta reda på texturella egenskaper av insamlade bergartsprover från fält. Syftet med denna studie var att undersöka om det fanns en storleks- och formdistribuering av magmafläckarna samt om de olika magmafläckarna är systematiskt distribuerade i flodbädden. Tidigare studier har antytt var undersökta magmakanalsystemen kan finnas samt hur blandningsprocesser för magma går till med hjälp av liknande metoder. Redan genomförda fältstudier har samlat in allt råmaterial som ligger till grund för denna studie. Fem olika magmatyper har beskrivits och påvisades interagera. Det fanns en ”värdmagma” som de andra fyra magmatyperna var exponerade som fläckar i. De statistiska analyserna inkluderade kartering av de fläckliknande magmaformerna baserat på foton tagna med hjälp av en drönare. Tre olika mjukvaror användes för att samla in, mäta och analysera data; Inkscape, Image J och Excel. Resultaten från den statistiska analysen visade att ungefär 80 % av alla fläckar existerade inom ett areaintervall mellan 0 – 0,1 m2 . Denna studie innehåller en diskussion om implikationerna av magmafläckarnas distribution med avseende på magmaomladdning och -processer inuti denna sektion av magmakammaren. Den generella formdistributionen visade en indikation för att alla fläckar tenderar att vara mer rundade och kvadratiska. Detta antyder att magmans blandningsförlopp troligtvis inträffade vid ungefär samma tidpunkt, under en flytande fas.
22

Étude dynamique des systèmes multiples de petits corps : application au système de Pluton

Beauvalet, Laurène 14 December 2011 (has links) (PDF)
Un système multiple est un ensemble de petits corps du Système solaire en interaction gravitationnelle et orbitant autour de leur barycentre, lui-même en révolution autour du Soleil. L'observation astrométrique de ces systèmes permet d'avoir accès à des paramètres physiques plus difficilement accessibles par d'autres techniques, en premier lieu la masse des composantes du système. Pour déduire des observations la valeur de ces paramètres, nous avons créé un modèle numérique à N-corps. Notre modèle intègre les équations variationnelles associées aux mouvements orbitaux pour permettre un ajustement du modèle par la méthode des moindres carrés. Notre modèle a par la suite été appliqué au système de Pluton, le système multiple pour lequel on dispose de la plus longue période d'observations. Ce système s'apparente aussi bien aux systèmes planétaires classiques, Pluton étant un objet en équilibre hydrostatique et Nix, Hydra et S2011(134340)1 ayant des masses négligeables face à lui, qu'à un système de petits corps, le principal satellite du système, Charon, étant suffisamment massif pour faire de Pluton/Charon un objet binaire. De manière à modéliser aussi bien le mouvement héliocentrique de Pluton, fortement perturbé par ses satellites, que le mouvement des dits-satellites, nous avons intégré les équations du mouvement dans un repère d'axes fi xes centrés sur le barycentre du Système Solaire, en prenant en compte l'influence des planètes et des aplatissements polaires au second ordre de Pluton et Charon. Le modèle numérique ainsi obtenu est ajusté par la méthode des moindres carrés à des observations simulées ou réelles. Dans un premier temps, en ajustant notre modèle à des observations simulées, nous avons étudié l'évolution de l'incertitude des masses de Nix et Hydra. Nous avons montré que leurs masses ne seront probablement réellement contraintes que grâce aux observations de New Horizons. Nous avons également montré que l'effet de l'aplatissement de Pluton et Charon sur les mouvements orbitaux n'est pas assez important pour pouvoir être déduit des observations astrométriques seules. Nous avons également utilisé cette méthode pour quantifi er le futur apport de Gaia à notre connaissance du système. Par la suite, nous avons ajusté notre modèle aux observations réelles du système de Pluton. Nous avons obtenu des résidus astrométriques proches de ceux obtenus par de précédents modèles, malgré des valeurs des masses de Nix et Hydra très différentes de celles obtenues par ces précédentes études. Néanmoins, les masses de ces derniers étant très faiblement contraintes actuellement, nos estimations et celles obtenues par d'autres restent cohérentes. La solution du mouvement des satellites ainsi obtenue a été utilisée lors de notre ajustement de manière reproduire de la façon la plus exacte possible le mouvement de Pluton autour du barycentre de son système. Finalement, nous avons adapté notre modèle au système d'Eugénia pour lequel nous avons trouvé des résultats compatibles avec ceux des études précédentes du système. Néanmoins, notre solution dérivant d'un ajustement sur une plus longue plage d'observations, notre modélisation du système sera valide sur une plus grande période de temps.
23

Constructing a sheeted magmatic complex within the lower arc crust : insights from the Tenpeak pluton, North Cascades, Washington

Chan, Christine F. 19 November 2012 (has links)
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
24

Les plutons de Guider et de Bossoum-Pologozom (chaîne panafricaine au Nord-Cameroun): analyses pétrographique, structurale, magnétique, géochronologique et implications géodynamiques

Dawaï, Daouda 14 March 2014 (has links) (PDF)
Le pluton de Guider (PG), mis en place vers 593 Ma dans des orthogneiss, est composé principalement de diorite et de syénites transalcalines. Le magma parent de ce pluton serait issu d'une large fusion partielle d'une source basaltique, et les différents faciès résulteraient de processus de cristallisation fractionnée, assimilation crustale et métasomatisme. Le pluton de Bossoum-Pologozom (PBP) est composé de syénite et de syénogranite ferro-potassiques issues d'un magma granodioritique essentiellement par cristallisation fractionnée. L'encaissant du PG qui s'est mis en place vers 632 Ma, a subi une déformation transpressive à cisaillement pur dominant dextre, orienté N-S à NNE-SSW, qui a débuté vers 612 Ma. Les microstructures et l'ASM suggèrent que sa mise en place a eu lieu avant la fin de la déformation transpressive de son encaissant. Le PBP s'est mis en place vers 566 Ma, au sein d'orthogneiss et granites syntectoniques. L'installation des granites syntectoniques est synchrone d'un second épisode cisaillant, postérieur à l'épisode transpressif dextre sus-cité. Le sens de cisaillement de ce second épisode reste incertain. Les structures internes du PBP suggèrent qu'il est syn- à tardi-tectonique du second épisode de la transpression. Cette transpression régionale est la conséquence de la collision entre les domaines Mayo-Kébbi et NW-Cameroun qui se serait achevée vers 566 Ma. Enfin le magmatisme transalcalin du PBP est semblable et contemporain du magmatisme de certains plutons de l'Est du Nigéria et du Nordeste brésilien, ce qui à suggère que le second épisode de transpression du secteur de Guider est contemporain des grands cisaillements de la zone de Patos.
25

Correlation of Magma Intrusions in the Slaufrudalur Pluton With 3D Modeling and Photogrammetry / Korrelation av magma intrusion i Slaufrudalur plutonen med 3D modulering och fotogrammetri

Solberg, Maximilian January 2022 (has links)
Photogrammetry has become a great tool when analyzing geological outcrops. The Slaufrudalur plutonis located in southeast Iceland and is composed of multiple granitic intrusions. With the help of 3Dmodeling and photogrammetry one of these intrusions is recreated to see if layers in the mountainsMosfell, Bleikitindur and Skeggtindur can be correlated. This project will help to understand thecorrelation of the layers and which places in the pluton should be further investigated in the future.                                Agisoft metashape was used to create a 3D model from aerial photographs, LIME was used to markthe layers in the model and MOVE was used to recreate the intrusion on the model. The 3D modelingshowed that the layers in the different mountains were at very similar altitudes and had very similarthicknesses. The intrusion model acted very similar in Mosfell and Bleikitindur and quite similar inSkeggtindur as well. An extension of the top of the intrusion showed that there is a possibility that theintrusion layer can be found in the northern part of the pluton. These findings show that there is apossibility that the intrusion could have covered the whole pluton. With more research this could leadto more knowledge about how the Slaufrudalur pluton was created. / Fotogrammetri har blivit ett väldigt bra verktyg för att analysera geologiska strukturer. Slaufrudalurplutonen ligger i Sydöstra Island och består av ett flertal felsiska intrusioner. Med hjälp av 3Dmodelering och fotogrammetri ska en av de felsiska intrusionerna i plutonen återskapas för att se ifalllager i Mosfell, Bleikitindur och Skeggtindur kan korreleras med varandra. Det här arbetet kommerbidra till mer förståelse kring Slaufrudalur plutonen och vilka ställen som skulle vara bra att undersökamer noggrant i framtiden.  Agisoft metashape användes för att skapa en 3D modell utifrån flygplansbilder, LIMEanvändes för att markera ut var lagergränserna fanns och MOVE användes för att återskapaintrusionerna i modellen. Modellerna visade att lagrena i bergen var på liknande altitud ochhade ungefär samma tjocklek. I Mosfell och Blekitindur var den återskapade intrusionenväldigt likformig, i Skeggtindur påminde den ganska mycket om hur den var i de andra bergenmen inte lika mycket. En förlängning av toppen på intrusionen visade att det möjligtvis går atthitta lagret i den norra delen av plutonen.Resultaten från det här arbetet visar att det finns en möjlighet att intrusionen kan ha täckt helaplutonen. Med mer forskning kan det här leda till mer kunskap om hur Slaufrudalur plutonenskapades.
26

Magnetická stavba, tok magmatu a tektonická deformace ve vulkano-plutonických systémech / Magnetic fabric, magma flow and tectonic deformation in volcano-plutonic systems

Tomek, Filip January 2015 (has links)
Magnetic fabric, magma flow and tectonic deformation in volcano-plutonic systems ABSTRACT This Ph.D. thesis aims to investigate dynamics of emplacement and tectonic history of selected volcano-plutonic complexes in a continental magmatic arc and back arc setting. The thesis presents new data sets from five field areas, presented in separate chapters, which could be viewed as representing a vertical sections through upper part of an intermediate to felsic magmatic system. From top to bottom in this ‛imaginary' vertical system, the examined units are: (1) andesitic lava domes and (2) sub-volcanic magma chambers (<3 km deep) of the Miocene Štiavnica volcano- plutonic complex, Western Carpathians (Slovakia), (3) Shellenbarger pluton (<3 km depth) within the mid-Cretaceous Minarets caldera, Sierra Nevada batholith in California (USA), and ~7-10 km deep granitoids of (4) Lower-Cretaceous Wallowa batholith, Blue Mountains province in Oregon (USA) and (5) Late Devonian Staré Sedlo complex, central Bohemian Massif (Czech Republic). The research incorporates extensive field and structural data, supported by analysis of igneous textures and anisotropy of magnetic susceptibility (AMS). The latter is further accompanied by detailed examination of magnetic mineralogy using thermomagnetic measurements and optical and back...
27

Åskkäpp, bössa och dunderpåk : Automatkarbinen i den svenska försvarsmakten / Thundercane, gun and thunderstick : The assault rifle in the Swedish Armed Forces

Lundin, Sven January 2010 (has links)
<p>Under 1990-talet märktes en tydlig förändring bland automatkarbinerna. De blev mer och mer anpassningsbara och fler tillbehör blev tillgängliga för soldaterna. Samtidigt blev automatkarbiner mer kompakta för att bli mer lämpliga för operationer i urbaniserad terräng och fordonstjänst. Med invasionen av Afghanistan och den därefter följande upprorsbekämpningen upplever många försvarsmakter problem, eftersom striderna sker på antingen väldigt korta eller väldigt långa avstånd. Den ena situationen kräver ett kompakt vapen för SIB medan den andra situationen kräver ett vapen med lång pipa för att kunna uppnå verkan mot en fiende som ofta anfaller från avstånd på 500 meter eller mer. Försvarsmakten hade just startat försök med en uppdaterad version av AK5 när de förband sig att bidra med en reguljär styrka till ISAF. Författaren är av åsikten att Försvarsmakten saknar ett vapensystem på grupp och plutonsnivå för att uppnå verkan på avstånd större än 400 meter som ofta är fallet. Denna uppsats syftar därför till att undersöka hur nästa svenska automatkarbin kan komma att se ut utifrån erfarenheter dragna ifrån Operation Enduring Freedom.</p> / <p>During the 1990ies there is notable change in the assault rifle. They start to get more and more adaptable with a lot more accessories being available to the user. At the same time the assault rifle moves from rifle to carbine as many models become shorter to better suit operations in urban terrainas well as riding in vehicles. With the invasion and the following counter-insurgency operation in Afghanistan a lot of armies are experiencing problems since combat takes places at either very short or long ranges. One calls for acompact carbine suited for close quarters battle and one for a long barrelled rifle which enables soldiers to engage the enemy who often attacks from ranges exceeding the 500 meter mark. The Swedish Armed Forces had just started testing a new updated version of their AK5 assault rifle called AK5C when they committed to contributing a regular force to ISAF. The Author is of the opinion that Swedish forces lack a weapon system on squad and platoon level to engage an enemy atgreater distance than 400m which is often the case. This paper seeks to take a look at what the next Swedish assault rifle could look like taking in mind the experiences from Operation Enduring Freedom.</p>
28

Åskkäpp, bössa och dunderpåk : Automatkarbinen i den svenska försvarsmakten / Thundercane, gun and thunderstick : The assault rifle in the Swedish Armed Forces

Lundin, Sven January 2010 (has links)
Under 1990-talet märktes en tydlig förändring bland automatkarbinerna. De blev mer och mer anpassningsbara och fler tillbehör blev tillgängliga för soldaterna. Samtidigt blev automatkarbiner mer kompakta för att bli mer lämpliga för operationer i urbaniserad terräng och fordonstjänst. Med invasionen av Afghanistan och den därefter följande upprorsbekämpningen upplever många försvarsmakter problem, eftersom striderna sker på antingen väldigt korta eller väldigt långa avstånd. Den ena situationen kräver ett kompakt vapen för SIB medan den andra situationen kräver ett vapen med lång pipa för att kunna uppnå verkan mot en fiende som ofta anfaller från avstånd på 500 meter eller mer. Försvarsmakten hade just startat försök med en uppdaterad version av AK5 när de förband sig att bidra med en reguljär styrka till ISAF. Författaren är av åsikten att Försvarsmakten saknar ett vapensystem på grupp och plutonsnivå för att uppnå verkan på avstånd större än 400 meter som ofta är fallet. Denna uppsats syftar därför till att undersöka hur nästa svenska automatkarbin kan komma att se ut utifrån erfarenheter dragna ifrån Operation Enduring Freedom. / During the 1990ies there is notable change in the assault rifle. They start to get more and more adaptable with a lot more accessories being available to the user. At the same time the assault rifle moves from rifle to carbine as many models become shorter to better suit operations in urban terrainas well as riding in vehicles. With the invasion and the following counter-insurgency operation in Afghanistan a lot of armies are experiencing problems since combat takes places at either very short or long ranges. One calls for acompact carbine suited for close quarters battle and one for a long barrelled rifle which enables soldiers to engage the enemy who often attacks from ranges exceeding the 500 meter mark. The Swedish Armed Forces had just started testing a new updated version of their AK5 assault rifle called AK5C when they committed to contributing a regular force to ISAF. The Author is of the opinion that Swedish forces lack a weapon system on squad and platoon level to engage an enemy atgreater distance than 400m which is often the case. This paper seeks to take a look at what the next Swedish assault rifle could look like taking in mind the experiences from Operation Enduring Freedom.
29

Petrologia e geoquímica de granitóides a sudeste da zona de cisalhamento Afogados da Ingazeira – PE Nordeste do Brasil

MELO, Evenildo Bezerra de 26 February 2004 (has links)
Submitted by Isaac Francisco de Souza Dias (isaac.souzadias@ufpe.br) on 2016-03-02T19:40:38Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE Evenildo de Melo.pdf: 12846711 bytes, checksum: 78cce42f5c2b4b7945cd698bf7c3a622 (MD5) / Made available in DSpace on 2016-03-02T19:40:38Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE Evenildo de Melo.pdf: 12846711 bytes, checksum: 78cce42f5c2b4b7945cd698bf7c3a622 (MD5) Previous issue date: 2004-02-26 / Os granitóides estudados se situam geotectonicamente na Faixa Pajeú- Paraíba, Domínio Tectônico Central da Província da Borborema, ao Sul da Zona de Cisalhamento Afogados da Ingazeira, tão proximais que não distam mais de 3 (três) Km do traço principal do cisalhamento. São corpos de pequenas dimensões, com áreas de exposição de até 20Km², denominados plútons Serra do Pereiro, Serra do Boqueirão, Açude do Caroá, Serra do Zuza e Serra do Minador. Os três primeiros são intrudidos no contato entre ortognaisses e metassedimentos (Complexo Sertânea) do Paleoproterozóico, enquanto os dois últimos fazem contato também com metassedimentos (Complexo São Caetano) do Eo- NeoProterozóico. Petrograficamente são monzonitos, monzogranitos, sienogranitos e álcalifeldspato- granitos contendo enclaves de quartzodioritos, quartzomonzodioritos, monzodioritos e granodioritos. A intrusão de Açude do Caroá é caracteristicamente quartzodiorítica a quartzomonzodioritica. Os plútons de Serra do Pereiro e Serra do Boqueirão são mais alongados, ao contrário de Serra do Zuza e Serra do Minador, sem orientação mineral, linear ou planar. Enclaves métricos a decimétricos, mostrando contatos crenulados e composição quartzomonzodiorítica a diorítica, são observados nos plútons Serra do Pereiro e Serra do Boqueirão, enquanto em Serra do Zuza e Minador predominam enclaves menores que decímetros, mais alongados e com composição mais granodiorítica. Dados de química mineral indicam biotitas enriquecidas na molécula de annita, com razão Fe / (Fe + Mg) variando desde 0,62 a 0,87, enquanto os anfibólios são cálcicos, ricos em ferro, classificados como hornblenda ferro-edenítica e hornblenda ferro-potássica-pargasíticas, cuja razão Fe / (Fe + Mg) varia desde 0,55 a 0,85. Os plagioclásios variam desde Ab83,3An16,7 a Ab61,6An38,4, dominantemente oligoclásicos, enquanto o K-feldspato varia no intervalo de Or100 a Or80Ab20. Utilizados para geotermobarometria, dados de química mineral determinaram pressões 3,57 to 5,86 +- 0,6 Kbar e as correspondentes temperaturas de 776,2°C a 892,5°C, para as intrusões quartzomonzodioríticas a quartzodioríticas de Açude do Caroá, com profundidade de alojamento da ordem 15Km. Seguiram-se todos os preceitos ao geobarômetro Alumínio em Hornblenda e ao geotermômetro anfibólio-plagioclásio, calculando-se as pressões usando a equação de Schmidt. A avaliação da temperatura (776°C a 812°C, sob pressão de 3,57 a 5,86Kbar) considerou apenas os pares anfibólio-plagioclásio, cujo equilíbrio foi testado através de diagramas de correlação entre as razões Na/Ca e Si/Al, adicionando este critério estatístico conjugal às restrições individuais tais como o teor em albita do plagioclásio ( inferior a 90%) e o respeito ao intervalo 0,45 a 0,65 para a razão Fe / (Fe + Mg) no anfibólio. Dados de litogeoquímica permitiram determinar a temperatura de saturação de zircônio, quando começa a cristalizar zircão, fase mineral cedo-formada em todas as rochas analisadas. Para os magmas que originaram as rochas máficas, os resultados se mostraram compatíveis com aqueles determinados por química mineral e, em geral, bastante coerentes: quartzomonzonitos e quartzodioritos de Açude do Caroá (872°C e 883°C, respectivamente), monzodiorito de Serra do Boqueirão (865°C), quartzodiorito de Serra do Pereiro (890°C) e granodioritos de Serra do Zuza (830°C a 862°C). Para os litotipos mais félsicos do pluton Serra do Minador, as temperaturas de saturação em Zr mostraram variação entre 779°C e 844°C, enquanto os de Serra do Zuza variaram desde 815°C a 909°C. A litogeoquímica dos elementos maiores mostra que os granitoides estudados são metaluminosos a peraluminosos, corroborando os dados obtidos com as composições das biotitas. Mostram teores de SiO2 variando desde 56% a 76%, (K2O / Na2O) > 1, baixos teores de CaO, sendo melhor classificados como álcali-cálcicos. Os granitoides mostram elevados teores de Ba, Zr, Y e Nb e baixos teores de Sr, semelhantes aos do tipo-A, mais caracteristicamente Serra do Pereiro, Serra do Boqueirão e Açude do Caroá. Os teores de Zr, Ba e Sr diminuem para os lititipos mais ricos em SiO2, o que não acontece com Y e Nb. Os padrões dos elementos Terras Raras - ETR, normalizados em relação ao condrito, revelam pronunciada anomalia negativa de Eu, corroborando a semelhança com os granitóides tipo A, mais pronunciada nos plútons Serra do Zuza e Serra do Minador. As razões Ce/Yb mais elevadas sugerem maior fracionamento para o plúton Serra do Zuza (56 a 75, nos granitoides e 29 a 38, nos enclaves máficos). Também se revela o mais regular e extensivamente rico em Th, explicando-se as anomalias radiométricas. O plúton Serra do Minador apresenta a menor razão entre aqueles Terras Raras, da ordem de 11 a 22, ao passo que Serra do Pereiro as correspondentes razões Ce/Yb variam desde 46 a 62. Os diagramas do tipo spider LILE/HFSE, multielementos, revelam que os granitoides dos plútons Serra do Minador, Serra do Pereiro, Serra do Boqueirão e Açude do Caroá são enriquecidos em relação ao manto primitivo, porém dez vezes menos que o plúton Serra do Zuza. Há depressão em Sr sugestiva de alcalinidade do magma. Dados combinados de Nd-Sr apontam para uma origem de crosta inferior (0 > Nd > -20 e 0 < Sr < 80), com protólito dominantemente ígneo, cujo T(DM) remete ao Transamazônico ( 1,8 a 2,0 Ga.). Idades absolutas obtidas pelo método U-Pb em zircão apontam para o plúton Serra do Pereiro 543 +- 7 Ma. e para o plúton Serra do Zuza 538 +- 23 Ma., dados que podem ser aproximados para 540Ma. Todos os plútons plotam como intra-placa e tardi-orogênicos, mas Serra do Zuza e Serra do Minador tendem a anorogênicos nos diagramas discriminantes de ambiente tectônico. Coexistência e mistura de magmas, nos plútons de Serra do Pereiro, Açude do Caroá e Serra do Boqueirão, são evidenciadas por: presença de enclaves microgranulares mostrando contatos crenulados e lobados com os granitoides hospedeiros; cristais de feldspatos cortando transversalmente o contato entre enclaves/granitoide hospedeiro; textura de desequilíbrio com feldspatos e anfibólios manteados; presença de apatita acicular ; e ainda xenocristais de feldspatos e fragmentos de rochas félsicas inclusas nas máficas. Os estudos de anisotropia de susceptibilidade magnética – ASM – realizados no plúton de Serra do Zuza revelaram um controle através de minerais paramagnéticos e o baixo grau de anisotropia indica inexistência de deformação no estado sólido e estruturas magnéticas adquiridas no estado magmático, sugestão confirmada pela falta de relação entre o grau de anisotropia e a susceptibilidade magnética total. Os padrões de lineação e foliação magnéticas resultam numa trama mista sem prioridade para qualquer dos elementos – linear ou planar – indicando que o plúton Serra do Zuza se alojou em um ambiente transtensional, vinculado com o traço do cisalhamento. O caimento preferencial das lineações é para Sudoeste ou Oeste- Sudoeste, espraiando-se para Sudeste e para Nordeste, donde se conclui um alojamento ascendente do magma procedente desde Sudoeste ou Oeste-Sudoeste. Finalmente, os menores valores de caimento das lineações magnéticas caracterizam maior distanciamento da raiz, o que também se evidencia pelo tamanho reduzido e forma mais alongada dos enclaves. Os dados possibilitam que os plútons Serra do Boqueirão e Serra do Pereiro representam nível crustal mais profundo do que Serra do Zuza, mas o magma, que aqui se alojou, teve procedência justamente do sentido oposto, sugerindo-se que se tratem de pontos transtensivos isolados, ao longo do traço da zona de cisalhamento de Afogados da Ingazeira, considerado como um limite isotópico e estrutural, de segunda ordem. / Granitoids founded at Pajeú-Paraiba belt, Alto Pajeú Terrain, Central Tectonic Domain of Borborema Province, as near as 3Km maximum at south of Afogados da Ingazeira shear zone were studied. Short outcropping at most 20Km² each, Serra do Pereiro, Serra do Boqueirão, Açude do Caroá, Serra do Zuza and Serra do Minador pluton. The three first bodies intruded orthogneiss and metassediments (Sertanea complex) from the age Paleoproterozoic while last two intrude early Neoproterozoic São Caetano complex too. Monzonites, monzogranites, sienogranites and alkali-feldspar-granites rocks, while quartzdiorites, quartz monzodiorites, monzodiorites and granodiorites are petrographical compositions of enclaves. Açude do Caroa pluton is characteristically quartz diorite and quartz monzodiorite. Serra do Pereiro and Serra do Boqueirão pluton are longest, the other way round Serra do Zuza and Serra do Minador pluton without foliation or lineation mineral. Metric and submetric enclaves reveal crenulate boundary and quartzmonzodioritc or dioritic composition at Serra do Pereiro and Serra do Boqueirão pluton, while there is smaller enclaves in Serra do Zuza and Serra do Minador pluton, leading decimeter to millimeter, longer and with more granodiorite in composition. Microprobe data point out biotites annite-rich, Fe / ( Fe + Mg) rate varies 0.62 to 0.87, while amphiboles are calcic, Fe-rich, named Fe-edenite hornblende and hornblend Fe-K-pargasitic, with rate Fe / (Fe + Mg) varying since 0.55 to 0.85. Plagioclases are Ab82.3 An16.7 until Ab61.6 An38.4 oligoclases, and K-feldspar varies since Or100 to Or80 Ab20. Microprobe data was applied to geothermobarometry to definite 3.57 to 5.86 +- 1.6 Kbar and temperatures since 776.2°C to 892.5°C for quartzmonzodiorites and quartzdiorites in Açude Caroá pluton, emplaced at 15 Km deep in crust. All path for Al-in-Hornblend barometry and amphibole-plagioclase geothermometer was regarded and calculate the pressures using Schmidt`s equation, regarding the interval 0.45 to 0.65 for a rate Fe / (Fe + Mg). The temperature evaluation counts only each amphibole plagioclase pair that equilibrium Na/Ca versus Si/Al has been verified through statistics correlation diagrams. This statistic criteria is grouped with other restrictions as the albite content plagioclase less than Ab90An10 and regard the interval 0,45 to 0,65 for a rate Fe / (Fe + Mg) of amphibole. Geochemical data in whole-rock calculate temperature Zr saturation when begin zircon crystallization, mineral phase common in most rocks. Mafic rocks and their magmas leading compatible results with microprobe data, as coherent as 872°C to 883°C for quartz monzodiorite and quartzdiorite of Açude do Caroá pluton, 865°C for monzodiorite of Serra do Boqueirão pluton, 890°C for quartzdiorite of Serra do Pereiro pluton and 830°C until 862°C for granodiorite of the Serra do Zuza pluton. Analogously in the type of rocks with more felsic mineral composition from Serra do Minador pluton, the temperatures of saturation in Zr show variation between 779°C and 844°C, while the Serra do Zuza`s types show variation between 815°C to 909°C. The geochemical of the bigger elements displays that the granitoids studied are metaluminous to peraluminous. It was took when this were compared with the biotites composition. It shows substances of SiO2 altering since 56% to 76%, (K2O / Na2O) > 1, low substance of CaO. So it's better classified lyke alkali-calcic. The granitoids show high purport of Ba, Zr, Y and Nb and low purport of Sr, as the same as the A-type granites. It can be seem in Serra do Pereiro, Serra do Boqueirão and Açude do Caroá. The substances of Zr, Ba and Sr get less in case of the type of rocks wealthy in SiO2. And it not happens with Y and Nb. REE patterns normalized for CHUR reveal Eu anomalies, as similarity as A-type Granitoids, mainly Serra do Zuza and Serra do Minador plutons. The higher relations Ce/Yb suggest a larger breach to the Serra do Zuza pluton (56 a 75 in granitoids and 29 to 38 in mafic enclaves) it is response to disclose the most regular an rich in Th, explaining the radiometric anomalies. Serra do Minador pluton exhibits the smallest relation between the REE, in class of 11 to 22, and in Serra do Pereiro the relations Ce/Yb changes since 46 to 62. The spiderdiagrams LILE/HFSE shows granitoids enriched, compared to the original mantle, in plutons of Serra do Minador, Serra do Pereiro, Serra do Boqueirão and Açude do Caroá. But this granitoids are ten times less enriched compared with Serra do Zuza pluton. There is a depression in Sr that suggests aluminous magma. Combined data of Nd-Sr aim to a lower crust origin (0 > Nd > -20 and 0 < Sr < 80) with protolite prevailing igneous, whose T (DM) send to Transamazonic ( 1.8 Gy. to 2.0 Gy). Absolut ages obtained by U-Pb in zircon method aim to the Serra do Pereiro 543 +- 7 Ma, and to the Serra do Zuza pluton 538 +- 23 Ma. This datas can be approximated to 540 Ma. All plutons are within plate and late orogenic, but Serra do Zuza and Serra do Minador plot as anorogenic in diagrams. There is features showing magma mixing evidences in Serra do Boqueirão pluton and Serra do Pereiro pluton and Caroá pluton, too: presence of microgranular enclaves showing crenular and cuspate contacts with hostless granitoids; feldspar crystals cutting crossly the contact between the hostless enclaves/granitoids; imbalance condition of texture with feldspar and amphibole manted; presence of acicular apatite; and feldspars xenocrystals and fragments of felsic rocks in mafic rocks. The lineation and foliation magnetic patterns results in a mixed texture without priority to any elements – linear or planar – showing the Serra do Zuza pluton took lodgings in a transtentional ambient, linked with the shear line. The preferential depression of the features is to the SW or WSW, widening to SE and NE, from we can conclude about an ascendant lodging of the magma that comes since SW or WSW. Finally, the less datas of depression of the magnetic lineations characterize amre separation from the rule. And that also is proved by reduced size and lengthened shape of enclaves. The data make possible that Serra do Boqueirão and Serra do Pereiro plutons represent crustal level deeper that Serra do Zuza. However, the magma which lodgings there, origins in the opositte direction, It suggests that this plutons are from the isolate relief points along the Afogados da Ingazeira shear zone, that is considered a isotopic and structural boundary.
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Préparation et analyses des observations de l'atmosphère et des glaces de Pluton par la mission NASA New Horizons à l'aide de modèles numériques de climat / Preparation and analysis of the observations of the atmosphere and ices of Pluto by the NASA new horizons spacecraft using numerical climate models

Bertrand, Tanguy 27 September 2017 (has links)
Le 14 juillet 2015, la sonde New Horizons a survolé Pluton et a révélé un monde glacé débordant d’activité. Pour interpréter les observations, nous avons développé deux modèles numériques, l’un simulant les interactions surface-atmosphère des espèces volatiles sur des milliers d’années, l’autre dédié au climat 3D complet de Pluton. Avec ces modèles, nous analysons les cycles annuels et paléoclimatiques des glaces. Nos simulations reproduisent la distribution des espèces volatiles observées à la surface de Pluton, ainsi que leur abondance dans l’atmosphère. Nous montrons que l’insolation sur Pluton et la nature de son atmosphère favorisent la condensation d’azote au fond du bassin Sputnik Planitia, comme observé. Nous simulons, sur des échelles de millions d’années, des écoulements glaciaires de la calotte de glace dans Sputnik Planitia, ainsi que la formation de glaciers de méthane à l’équateur, des résultats très cohérents avec les observations. Nous nous intéressons ensuite à l’état de l’atmosphère de Pluton en 2015 avec le modèle 3D, caractérisant les régimes de vents, formation des nuages, températures, etc.... Nos derniers résultats mettent en évidence la sensibilité de la circulation générale à la distribution de la glace d’azote à la surface et suggèrent une rétro-rotation dans l’atmosphère de Pluton, induite par les flux de condensation-sublimation de l’azote dans Sputnik Planitia. Nous montrons également que plusieurs phénomènes sont à l’origine de la couche limite froide observée dans Sputnik Planitia. Enfin, en reproduisant les processus qui mènent à la formation de la brume organique, nous parvenons à expliquer l’extension de la brume observée au pôle nord. / On July 14, 2015, the New Horizons spacecraft flew by Pluto and revealed an active frozen world.These observations call upon modelling efforts to complete their analysis and understand the mechanisms at play on Pluto. For this purpose, we have developed two numerical models of Pluto’s climate: a 2D model dedicated to the study of Pluto’s surface and a 3D model of Pluto’s atmosphere. We analyse the annual and paleoclimatic volatile cycles. Our simulations reproduce the distribution of the volatile observed on Pluto’s surface and their abundance in the atmosphere. We show that the solar insolation on Pluto and the nature of its atmosphere favour the condensation of nitrogen in the Sputnik Planitia basin, as observed. We simulate the glacial activity of the Sputnik Planitia ice cap on a timescale of millions of years, as well as the formation of methane glaciers at the equator. Our results are in agreement with the observations. We then focus on Pluto’s atmosphere in 2015 with the full 3D model where we performed a comprehensive characterization of the atmosphere: wind regimes, cloud formation, temperatures etc. ...We demonstrate the sensitivity of the general circulation to the distribution of the nitrogen ice on the surface and show that Pluto’s atmosphere currently undergoes retrograde rotation, induced by the condensation-sublimation of nitrogen in Sputnik Planitia. We also show that several phenomena originate at the cold boundary layer observed deep in Sputnik Planitia. Finally, by reproducing the processes that lead to the formation of organic haze, we simulate haze transport in the atmosphere and explain the greater extension of the haze observed at the north pole.

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