Les chondres, témoin des débuts du Système Solaire, ont une origine encore débattue. En particulier, l'origine de leurs olivines est encore mal comprise. Furent-elles formées par processus magmatique ou de condensation ? Héritées ou formées directement dans le chondre ? Pour répondre cette question, une étude chimique détaillée a été réalisée sur des inclusions vitreuses piégées dans les olivines magnésiennes d'Allende (CV3). Des images 3D et des profils chimiques en profondeur des éléments majeurs montrent un comportement chimique similaire à celui d'inclusions magmatiques synthétiques, un argument en faveur d'une origine magmatique. Les inclusions ont ensuite été chauffées à haute température (1 800 °C) grâce à une platine chauffante unique au monde, développée au cours du projet, afin d'étudier le verre homogène. Les teneurs élevées en Na2O des inclusions chauffées montrent que les inclusions évoluent en système fermé et que les olivines se sont formées dans un environnement riche en Na. Du fait de la volatilité du Na à haute température, un tel environnement est difficilement conciliable avec une formation des olivines par condensation ou magmatique au sein des chondres. Ceci suggère donc que les olivines sont héritées. Des mesures de REE ont été réalisées par SIMS dans les inclusions et leurs olivines hôtes afin de calculer le taux de cristallisation nécessaire à la formation de ces olivines. Les compositions chimiques des magmas parents calculés d'après ces taux de cristallisation correspondent à celles attendues d'après les études expérimentales déjà existantes. Celles-ci suggèrent la formation des olivines au sein de planétésimaux fondus de composition CV ou CI / Chondrules, witnesses of the beginning of the Solar System still have a debated origin ti this day. In particular, the origin of chondrules' olivines is still poorly understood. Were they formed by magmatism or condensation processes? Inherited or grown directly within the chondrule? In order to answer this, a detailed chemical study was undertook on glass inclusions trapped in Mg-rich olivines from Allende (CV3) meteorite. 3D images and chemical depth profiles showed a similar behavior between Allende's inclusions and synthetic magmatic ones, which is an argument in favor of a magmatic origin for olivines. Glass inclusions were then heated at high temperature (1 800 °C) via a new and unique heating stage developed during the project, in order to study the homogeneous glasses. High Na2O amounts in heated inclusions show that they behave as closed systems and that olivines formed in a Na-rich environment. Because Na is highly volatile at high temperatures, such an environment is hard to reconcile with olivines forming by condensation or magmatism within chondrules. This suggests that olivines are inherited. Measurements of REE were performed via SIMS in inclusions and hosts olivines in order to calculate the crystallization rates necessary to olivines formation. Chemical compositions of parent magmas, calculated from crystallization rates correspond to those expected from previous experimental studies. They suggest that olivines from chondrules form within molten planetesimals of global CI to CV composition

The Harrington Peak Quadrangle is located within the Caribou National Forest of southeast Idaho. Within this quadrangle are outcrops of olivine trachyte of Pliocene(?) age overlying sedimentary rocks of Mississippian to Tertiary age. The region contains thrust faults and later normal faults (generally trending north-south} formed during Basin and Range extension. The Largest outcrop of olivine trachyte (approximately1 1/2 X 3 km) probably formed as the result of a fissure eruption. Two other outcrop areas show evidence of being sites of local extrusion. Whole-rock chemical analyses revealed the olivine trachyte to have moderate amounts of SiO2 and Al2O3, high MgO and CaO, and K2O in excess over Na2O (approximately 2:1). Mineralogical characteristics include microphenocrysts of Mg-rich olivine and diopsidic augite in a groundmass of Ba-rich sanidine, diopsidic augite, Fe-Ti oxides, and less commonly phlogopite and/or plagioclase. The olivine trachyte closely resembles the ciminites from the Viterbo region of Italy and has some petrological and mineralogical similarities to many other continental potassic volcanic rocks. The olivine trachyte may have formed by partial melting of a heterogenous mica peridotite mantle source enriched in incompatible elements during a previous tectonic event.

Processes that take place in the Earth’s mantle are not accessible to direct observation. Natural samples of mantle material that have been transported to the surface as xenoliths provide useful information on phase relations and compositions of phases at the pressure and temperature conditions of each rock fragment. In the past, considerable effort has been devoted by petrologists to investigate upper mantle processes experimentally. Results of high temperatures, high pressure experiments have provided insight into lower crust-upper mantle phase relations as a function of temperature, pressure and composition. However, the attainment of equilibrium in these experiments, especially in complex systems, may be very difficult to test rigorously. Furthermore, experimental results may also require extrapolation to different pressures, temperatures or bulk compositions. More recently, thermodynamic modeling has proved to be a very powerful approach to this problem, allowing the deciphering the physicochemical conditions at which mantle processes occur. On the other hand, a comprehensive thermodynamic model to investigate lower crust-upper mantle phase assemblages in complex systems does not exist. ¶ In this study, a new thermodynamic model to describe phase equilibria between silicate and/or oxide crystalline phases has been derived. For every solution phase the molar Gibbs free energy is given by the sum of contributions from the energy of the end-members, ideal mixing on sites, and excess site mixing terms. It is here argued that the end-member term of the Gibbs free energy for complex solid solution phases (e.g. pyroxene, spinel) has not previously been treated in the most appropriate manner. As an example, the correct expression of this term for a pyroxene solution in a general (Na-Ca-Mg-Fe2+-Al-Cr-Fe3+-Si-Ti) system is presented and the principle underlying its formulation for any complex solution phase is elucidated.¶ Based on the thermodynamic model an algorithm to compute lower crust-upper mantle phase equilibria for subsolidus mineral assemblages as a function of composition, temperature and pressure has been developed. Included in the algorithm is a new way to represent the total Gibbs free energy for any multi-phase complex system. At any given temperature and pressure a closed multi-phase system is at its equilibrium condition when the chemical composition of the phases present in the system and the number of moles of each are such that the Gibbs free energy of the system reaches its minimum value. From a mathematical point of view, the determination of equilibrium phase assemblages can, in short, be defined as a constrained minimization problem. To solve the Gibbs free energy minimization problem a ‘Feasible Iterate Sequential Quadratic Programming’ method (FSQP) is employed. The system’s Gibbs free energy is minimized under several different linear and non-linear constraints. The algorithm, coded as a highly flexible FORTRAN computer program (named ‘Gib’), has been set up, at the moment, to perform equilibrium calculations in NaO-CaO-MgO-FeO-Al2O3-Cr2O3-Fe2O3- SiO2-TiO2 systems. However, the program is designed in a way that any other oxide component could be easily added.¶ To accurately forward model phase equilibria compositions using ‘Gib’, a precise estimation of the thermodynamic data for mineral end-members and of the solution parameters that will be adopted in the computation is needed. As a result, the value of these parameters had to be derived/refined for every solution phase in the investigated systems. A computer program (called ‘GibInv’) has been set up, and its implementation is here described in detail, that allows the simultaneous refinement of any of the end-member and mixing parameters. Derivation of internally consistent thermodynamic data is obtained by making use of the Bayesian technique. The program, after being successfully tested in a synthetic case, is initially applied to pyroxene assemblages in the system CaO-MgO-FeO-Al2O3-SiO2 (i.e. CMFAS) and in its constituent subsystems. Preliminary results are presented.¶ The new thermodynamic model is then applied to assemblages of Ca-Mg-Fe olivines and to assemblages of coexisting pyroxenes (orthopyroxene, low Ca- and high Ca clinopyroxene; two or three depending on T-P-bulk composition conditions), in CMFAS system and subsystems. Olivine and pyroxene solid solution and end-member parameters are refined, in part using ‘GibInv’ and in part on a ‘trial and error’ basis, and, when necessary, new parameters are derived. Olivine/pyroxene phase relations within such systems and their subsystems are calculated over a wide range of temperatures and pressures and compare very favorably with experimental constraints.

Cette thèse est consacrée à l'analyse des données multispectrales de la caméra infrarouge NIR de la sonde Clementine. La Lune est le seul corps planétaire pour lequel on dispose à la fois d'une vérité terrain (échantillons lunaires) et de données de télédétection globales non perturbées par une atmosphère. C'est donc le cas le plus favorable pour tester et valider des méthodes de télédétection, ces méthodes pouvant ensuite être extrapolées à d'autres corps du système solaire. Les données NIR, bien que dans le domaine public depuis 1995, n'avaient jamais été exploitées auparavant du fait de problèmes majeurs d'étalonnage. La première partie de ce travail a consisté à s'affranchir des problèmes d'étalonnage, donnant ainsi accès à des observations inédites couvrant la totalité de la surface lunaire. Ces observations ont ensuite été mises à profit pour aborder les problèmes de l'identification des minéraux et de l'extrapolation de la connaissance de quelques sites à l'ensemble du satellite. Des zones riches en olivine, minéral associé au manteau lunaire et rarement détecté en surface, ont été mises en évidence dans les régions des cratères Aristarchus et Copernicus. L'analyse systématique des propriétés spectrales et chimiques d'échantillons lunaires représentatifs, couplée aux données NIR, a ensuite permis de mettre en place une méthode de cartographie quantitative de la teneur en fer des sols observés, clarifiant ainsi le lien entre information spectrale et chimique. Cette méthode permet de discriminer entre les effets de composition et les effets d'altération de la surface suite aux impacts de micrométéorites et de particules du vent solaire. L'expérience acquise dans le cas lunaire est directement transposable à l'étude d'autres surfaces rocheuses sans atmosphère (cas de Mercure et des astéroïdes), et représente un premier pas vers le cas plus difficile de Mars (présence d'une atmosphère)

The present work focuses on mineral reactions and slag formation of LKAB olivine iron ore pellets (MPBO) subjected to reducing conditions in the LKAB experimental blast furnace (EBF). The emphasis is on olivine reactions with surrounding iron oxides. Many factors influence the olivine behaviour. The study was performed by use of micro methods; optical microscopy, micro probe analysis, micro Raman and Mössbuer spectroscopy and thremodynamic modeling. During manufacturing, in oxidising atmosphere at high temperature (1350°C), olivine alterations occur through slag formation and rim reactions with iron oxides and other additives. To be able to describe olivine behaviour in the rather complex blast furnace reduction process one has to consider factors such as reactions kinetics, reduction degree of iron oxides, vertical and horizontal position in the furnace and reactions with alkali. Samples were collected from the EBF both from in shaft probing during operation and from excavation following quenching of the EBF. The initial slag forming olivine consist of primary forsterite – (Mg1.9Fe0.1)SiO4 – with inclusions of hematite and an amorphous silica rich phase, a first corona with lamellae of magnesioferrite, olivine and orthopyroxene, a second corona of amorphous silica and magnesioferrite. During reduction in the upper shaft in the EBF (700-900°C) Fe3+ reduces to Fe2+. The amorphous silica in the second corona absorbs alkali, Al, Fe2+, Mg, and Ca and form glasses of varying compositions. The lamellae in the first corona will merge into a single phase olivine rim. With further reduction the glasses in the second corona will merge with the olivine rim forming an iron rich olivine rim and leaving the elements that do not fit into the olivine crystal lattice as small silicate glass inclusions. Diffusion of magnesium and iron between olivines and iron oxides increase with increasing temperature in the lower shaft of the EBF (750-1100°C). In the cohesive zone of the EBF (1100-1200°C) Fe2+ is not stable any longer and Fe2+ will be expelled from the olivine as metallic iron blebs, and the olivine will form a complex melt with a typical composition of alkali-Al2O3-MgO-SiO2. Alkali plays an important role in this final olivine consumption. The quench time for samples collected with probes and excavation are minutes respectively hours. A study of the quench rate’s effect on the phases showed no differences in the upper shaft. However, in the lower shaft wüstite separates into wüstite and magnetite when wüstite grows out of its stability field during slow cooling of excavated samples. There is also a higher alkali and aluminium deposition in the glass phases surrounding olivines in excavated pellets as a result of alkali and aluminium gas condensing on the burden in the EBF during cooling. Coating applied to olivine pellets was studied in the EBF with the aim to investigate its behaviour, particularly its ability to capture alkali. The coating materials were kaolinite, bauxite, olivine and limestone. No significant reactions were observed in the upper shaft. In the lower shaft a majority of the phases were amorphous and reflecting the original coating compositions. Deposition from the EBF gas phase occurs and kalsilite (KAlSiO4) is found in all samples; coating used for binding alkali is redundant from a quality perspective.

Four different kinds of filter-materials with reactive surfaces have been studied concerning their capacity to absorb heavy metals in leachate from a municipal waste deposit. The heavy metals studied were: lead, cadmium, copper, mercury, chromium, nickel and zinc. The leachate contains high levels of dissolved organic carbon (DOC) and has a high pH-value along with a high buffer capacity. These characteristics of the leachate make it difficult to remove pollutants and require efficient filters. The filters that were examined in the report are blast-furnace slag with CaO, sand covered with iron oxides, olivine and nepheline. The experiment was carried out in two sets, starting with batch experiments followed by a column study. The objective of the batch experiments was to find out how variations in pH affected the sorption capacity of the materials. The interval used during the test was from pH 5 to pH 10. The computer program VisualMinteq was used to evaluate the dominating sorption processes when the materials interacted with the solutions. Two different kinds of solutions were used in the batch experiment. One of them was the leachate, to which known concentrations of heavy metals were added (about 1 μM) and the other consisted of sodium nitrate, a solution without organic compounds, which was used as a reference. The sodium nitrate solution was also spiked with the same concentration of heavy metals as the leachate. The results from the batch experiment showed that the sorption of heavy metals was lowered if the DOC level was high. No relation between pH and sorption ability could be found for the leachate, but for some metals in the sodium solution a higher pH improved the removal of heavy metals. The two materials that showed best results in the batch experiment were the blast-furnace slag and the sand with iron oxides. These materials were used in the column study. The olivine material was somewhat better than the nepheline in the batch experiment. Four columns were used in the column study, two for each material. Leachate with heavy metals was pumped into the columns with a specific flow rate; at first a low flow rate was used and when half the experiment time had passed the flow rate was increased. The flow rates used were 0.12 m/24 h and 0.62 m/24 h. The outcome of the column experiment showed that the slag had the highest ability to adsorb metals. The metal sorption was over 60 percent for lead, cadmium and zinc, where the highest sorption was obtained for lead. No affects were noticed when the flow rate was increased. / I detta examensarbete har fyra olika reaktiva filtermaterials kapaciteter att ur deponilakvatten avskilja tungmetallerna bly, kadmium, koppar, kvicksilver, krom, nickel och zink testats. Deponilakvatten är ett avloppsvatten med höga halter organiskt material (DOC), högt pH och en hög buffertkapacitet. Dess sammansättning ställer stora krav på ett filter och närvaron av ligander påverkar sorptionprocesserna. Filtren som ingått i studien är kalciumoxiddopad masugnsslagg, järnoxidtäckt sand, olivin och nefelin. Försöken utfördes i två delar, med inledande skakförsök och därefter kolonnförsök. I båda försöken användes lakvatten med en extra tillsats av tungmetaller. I skakförsöken användes även natriumnitrat; ett referensvatten utan organiska ligander, även det spikat med tungmetaller. I skakförsöken studerades avskiljningens pH-beroende för de olika filtren, med ett pH-intervall på ca 5 – 10. Därefter modellerades resultaten i jämviktsprogrammet VisualMinteq för att fastställa vilka processer som styr avskiljningen. Skakförsöken och kolonnförsöken utfördes båda i klimatrum vid 8 ºC, för att efterlikna markens naturliga temperatur. Resultaten från skakförsöken visade att masugnsslagg och järnoxidsand gav bäst avskiljning för de flesta tungmetaller. Olivin och nefelin var sämre metallsorbenter, där olivin uppvisade något bättre resultat än nefelin. Inget tydligt pH-beroende för lakvattnet kunde utläsas, men för natriumnitratlösningen gav en pH-höjning en ökad sorption för vissa metaller. Den kemiska jämviktsmodelleringen visade att den dominerande processen i filtermaterialen var sorption på filterytorna. De två filtermaterialen som visade bäst resultat i skakförsöken (slagg och järnoxid) studerades vidare i kolonnförsök, där ett bestämt lakvattenflöde pumpades genom kolonner packade med materialen. Två olika flödeshastigheter testades (0,12 m/dygn och 0,62 m/dygn) och sorptionen av metaller analyserades. Slaggen uppvisade högst avskiljningskapacitet av de studerade filtren. De metaller som sorberades bäst var bly, kadmium och zink (över 60 % avskiljning), där den högsta sorptionen erhölls för bly. Gemensamt för både skak- och kolonnförsöken var att sorptionen försvårades då halten organiskt material (DOC) ökade, vilket beror på att DOC konkurrerar med de reaktiva ytorna på filtren om att binda den fria metalljonen. Ingen minskande avskiljningseffekt av en flödesökning kunde utläsas.

Natural and synthetic common-rock forming minerals were examined using single-crystal X-ray diffraction (SXRD) and electron microprobe (EMP) analyses. The influences of common defect features, such as inclusions in spinel and oxygen positional disorder and twinning in kalsilite, were reported on the respective structures. The case studies show that these defect features could lead to a misinterpretation of X-ray intensity data. The structural interpretations obtained from these XSRD analyses could be significantly different when physical properties of the crystals are considered.In the second part of my dissertation, comparative crystal chemical studies on mantle-derived minerals such as spinel, clinopyroxene, and olivine are reported. These studies were carried out to examine temperature, pressure, and compositional effects on the structures of these phases. In particular, packing arrangements of oxygen atoms were examined in detail to investigate how the packing affects element partitioning among upper-mantle minerals. At ambient conditions, oxygen packing is more distorted in the order of spinel < olivine < clinopyroxene. The packing of oxygen atoms in olivine might have a significant control on element substitutions at high pressure. Because elements whose radius is larger than that of Mg distort the packing of mantle olivine (Fo~89), olivine might limit the amount of those elements, such as Fe2+, entering the structure. In contrast, substitutions of smaller cations in C2/c clinopyroxenes increase packing distortion. For clinopyroxenes enclosed in peridotite and eclogite, higher equilibration pressures are associated with more distorted, less efficiently packed structures. Unlike many minerals reported in Thompson and Downs (2001), spinel becomes more packed with rising temperature when intracrystalline cation exchange reactions are possible. Despite wide chemical variations, spinel samples from one geological environment display a constant packing distortion, which might suggest that spinel is capable of achieving an optimal packing configuration at a given P and T.

Methane (CH4) plays an important role in regulating Earth’s climate. Its atmospheric concentrations are related to both biotic and abiotic processes. The biotic one can be formed either by chemoautotrophic or heterotrophic pathways by methanogens. Abiotic CH4 formation can occur from several sequential reactions starting with H2 production by serpentinization of Fe-bearing minerals followed by Fischer-Tropsch Type reactions or thermogenic reactions from hydrocarbons. In the presence of suitable electron acceptors, microbial oxidation utilizes CH4 and contributes to regulating its emission.  From the perspectives of astrobiology and Earth climate regulation, this thesis focuses on: (1) Dynamics of CH4 formation and oxidation in lake sediments (Paper I), (2) Constructing an automatic flux chamber to facilitate its emission measurements (Paper II), (3) dynamics of both abiotic and biotic CH4 formation processes related to olivine water interaction in temperature range 30 - 70°C (Paper III and IV). Paper I showed that potential CH4 oxidation strongly correlated to in situ its formation rates across a wide variety of lake sediments. This means that the oxidation rates could be enhanced in environments having the high formation rates. Thereby, the oxidation would likely be able to keep up with potentially increasing the formation rates, as a result diffusive CH4 release from freshwater sediments might not necessarily increase due to global warming. Paper II presented a new automated approach to assess temporal variability of its aquatic fluxes. Paper III and IV together revealed that H2 can be formed via olivine-water interaction. Abiotic CH4 formation was formed likely by Fischer-Tropsch Type reactions at low inorganic carbon concentration but by thermogenic processes at high inorganic carbon concentration. Paper IV showed that biotic methanogenic metabolism could harvest H2 and produce CH4. The dynamics of these processes seemed strongly affected by carbonate chemistry. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Submitted.

Novel techniques for in-situ lead isotope analysis of melt inclusions using multicollector inductively coupled plasma mass spectrometry, and parallel Faraday cup and ion counter detection have been developed. These provide for measurement of the critical 204Pb isotope, which has been unavailable in melt inclusion Pb isotope studies, but requires on-line determination of 200Hg to correct for 204Hg isobaric interferences. External standardisation allows for effective mass fractionation correction and ion counter gain calibration. An off-line Tau correction was applied and standard glass analyses suggest that this correction provides more accurate and precise results.

Foram estudados as propriedades de absorção ótica, de termoluminescência e de ressonância paramagnética eletrônica do mineral natural de silicato de nome MONTICELITA do grupo Olivina, para caracterização desse mineral, cuja formula química é CaMgSiO4. A absorção ótica mostrou que há três bandas de absorção em 450 nm, 660 nm e 1050 nm. As duas primeiras bandas, a primeira no azul e a segunda no amarelo-vermelho são responsáveis pela cor verde da Monticelita. Essas duas bandas são consequência do elemento cromo contido no mineral absorver fótons do feixe universal no visível de frequências centradas em 450 nm e 660 nm. A banda em 1050 nm é devido ao Fe2+. As curvas de emissão de uma amostra de Monticelita irradiada com raios gama de doses entre 10 e 1000 Gy apresenta três picos em 150 °C , 270 °C e 370 °C . Pelo método da deconvolução e de várias taxas de aquecimento foram obtidos energia E1=1,35 eV e fator de frequência s1=4,98x1011 s-1 para o pico 270 °C e E2=1,70 eV e s2=1,88x1011 s-1 para pico 370 °C . A irradiação com raios gama de doses entre 5 kGy e 50 kGy produziram pico TL de 380 °C com intensidade TL em função da dose linear e crescente. Este resultado e importante para dosimetria da radiação de altas doses. O espectro EPR de uma amostra natural, mostrou um resultado não esperado e interessante. Além dos sinais típicos de interação hiperfina do Mn2+, um sinal avantajado de g =6,34 indica que o ferro formou moléculas de hematita, Fe2O3. Esse sinal desaparece com aquecimento acima de 800 °C de recozimento, dando origem dipolos magnéticos de Fe3+, que dá origem a um sinal típico em g =2. Esta descrição mostra bem a caracterização do mineral Monticelita. / The properties of optical absorption, thermoluminescence and electron paramagnetic resonance of natural silicate mineral named MONTICELLITE belonging to Olivine group have been investigate in order to characterize this mineral of chemical formula CaMgSiO4. The optical absorption spectrum has shown that there are three bands in visible and near infrared. They occur at 450, 660 and 1050 nm. The two first absorption bands, first one around blue and second one around yellow-red are responsible for green colour of mineral. It was shown that these two absorption bands are due to absorption by chromium contained in the material of 450 nm photon and 660 nm photon from incident beam in the spectrophotometer causing excitation from fundamental to two excited states. 1050 nm band is due to Fe2+. Glow curves of Monticellite sample irradiated with &gamma;-rays have shown TL peaks at 150, 270 e 370 °C. Using deconvolution method and various heating rates method following activation energy and frequency factor values for 270 °C peak, E1=1.35 eV and s1=4,98x1011 s-1 and for 370 °C peak E2=1.70 eV and s2=1,88x1011 s-1. Irradiation with y-rays with dose varying from 5 to 50 kGy a linear TL vs dose curve was obtained. This result shows that Monticellite Mineral can be used for high dose radiation dosimetry. The EPR spectrum of the natural sample presented an unexpected and interesting result. Besides a typical six lines due to hyperfine interaction in Mn2+ ion, a large signal with g =6,34 indicate an aggregate of hematite (Fe2O3). This signal changes into Fe3+ signal with g =2, under annealing at high temperatures of 800 to 1100 °C. Altogether these results characterize sufficiently enough the mineral Monticellite.