This study addresses the origin of the combined He-Ne-Ar-Xe noble gas isotopic variation in mantle derived oceanic basalts. High precision heavy noble gas compositions of basalts from the Rochambeau Rift along the Northwestern Lau Basin, the Gakkel Ridge, the Southeast Indian Ridge and the South Atlantic Ridge presented here confirms fundamental differences between the volatile constituents of the depleted mid-ocean ridge basalt (MORB) source and plume sources. We find that the depleted MORB mantle is characterized by systematically lower proportions of Pu-fission derived Xe than the Iceland plume and the Samoan-like plume sampled at the Rochambeau Rift. These two plume sources are associated with low radiogenic \(^{129}Xe/^{130}Xe\) ratios that are not attributable to recycled atmosphere and must sample ancient (4.45 Ga) volatile rich mantle reservoir that experienced a lower degree of mantle processing than the depleted MORB source. I report \(^{128}Xe/^{130}Xe\) ratios in excess with respect to the atmosphere in deeply erupting Gakkel lavas, similar to mantle derived volatiles in natural gas samples. Deconvolution of fission derived xenon isotopes indicate that natural gas samples and the Gakkel MORBs are derived from the same volatile depleted mantle reservoir. The radiogenic He isotopic composition, the low estimated ratio of Pu to U derived xenon isotopes, and the low \(^{129}Xe/^{130}Xe_E\) ratio found in the source of the West Volcanic Zone (WVZ) along the Gakkel Ridge indicates the presence of increased amounts of recycled atmospheric volatiles. I suggest that the low \(^{129}Xe/^{130}Xe\) ratio beneath the WVZ cannot be explained by sampling an ancient (>4.45 Ga) lithospheric mantle component that evolved in isolation from convection throughout Earth's history. Instead, the Xe isotopic composition may be consistent with the presence of subduction derived metasomatizing fluids with atmospheric heavy noble gases trapped in the sub-continental lithospheric mantle sampled along the ridge. Available Ne isotope MORB data and new high precision Ne data presented in this study (including basalts from the East Pacific Rise, the Galapagos Spreading Center, and the Juan de Fuca Ridge) allows me to construct a combined He-Ne isotope distribution and infer first order source mixing systematics in the upper mantle. / Earth and Planetary Sciences

We have built an imaging mass spectrometer adapted for ultrashort laser pulses as its ionization technique, as an alternative to other imaging techniques. Before my arrival, the mass spectrometer has only been subject to preliminary tests on noble gases. Since then, we’ve made some modifications to the system in order to properly analyze solids. This thesis shows how we obtain our ultrashort laser pulses, the inner workings of our homemade imaging mass spectrometer, and the results that we’ve obtained with it so far. We tested two modes of operation concerning the extraction of the ions from the system into the mass analyzer: continuous and pulsed. We discuss the advantages and disadvantages of each configuration. We also display preliminary imaging results with our imaging technique of a simple WO3 and ITO structure. We conclude by comparing the resolution of this image to the different techniques in imaging mass spectrometry, how we can further improve our mass spectrometer, and the future use of this machine. Nous avons construit un spectromètre de masse adapté pour les pulses de laser très courts comme technique d’ionisation, pour acquisition des images d’un échantillon. Avant je suis arrivé, le spectromètre de masse avait seulement été utilisé pour des tests préliminaires de gaz nobles. Depuis ce moment, nous avons modifié le système pour analyser les solides. Cette thèse démontre comment on obtient nos pulses de laser très courts, comment notre spectromètre fait maison fonctionne et les résultats nous avons obtenus jusqu’à présent. Nous avons testé deux configurations différentes au sujet de l’extraction des ions du système : constant et pulsé. Nous discutons aussi les avantages et désavantages de chaque mode d’opération. Nous démontrons aussi des images préliminaires d’un substrat mixte de WO3 et ITO. Nous concluons par comparer la résolution des images aux autres techniques de collection d’images, comment nous pouvons améliorer notre spectromètre de masse et les plans pour la machine dans le futur.

Im Rahmen der Dissertation wurden an Wässern und freien Gasen aus Thermalquellen sowie an weniger als 5 Millionen Jahre alten basischen Vulkaniten des zentralandinen Puna-Hochplateaus (NE-Argentinien) umfangreiche element- und isotopengeochemische Untersuchungen durchgeführt und die Edelgasgehalte und -isotopensignaturen in diesen Medien bestimmt. Damit soll ein Beitrag zum besseren Verständnis der jüngeren Subduktionsgeschichte im Bereich der südlichen Zentralanden geleistet, die Wechselwirkungen zwischen ozeanischer Unter- und kontinentaler Oberplatte sichtbar gemacht und die Edelgassystematik verbessert werden. Wie die Ergebnisse der Untersuchungen an Gasen aus den Thermalquellen der Puna-Region zeigen, ist der Anteil an Mantel-Helium in den Thermalquellen dieser Region mit bis zu 67 % wesentlich höher als in der westlich gelegenen vulkanisch aktiven Westkordillere und den anderen angrenzenden Gebieten. In einigen Quellen konnten sogar Anteile an Mantel-Neon nachgewiesen werden, was aufgrund von Überlagerungen mit Neon atmosphärischen und krustalen Ursprungs weltweit bisher nur vereinzelt gelungen ist. Für kontinentale Bereiche mit großer Krustendicke ist ein solch starker Mantelgasfluss äußerst ungewöhnlich und bedeutet, dass Mantelschmelzen bis in die Kruste aufgedrungen sind und tief reichende Wegsamkeiten existieren, so dass die Mantelgase aufsteigen können, ohne stark krustal beeinflusst zu werden. Dass im Bereich der Puna rezent Mantelmaterial in die Kruste aufsteigt, zu diesem Ergebnis kommen auch aktuelle seismologische Untersuchungen. Zudem wurden junge, vorwiegend monogenetische Basalte bis basaltische Andesite geochemisch auf ihre Haupt-, Neben- und Spurenbestandteile sowie ihre Gehalte an Seltenenerdenelementen hin untersucht. Auch wurden die Isotopenverhältnisse von Sr, Nd und Pb in den Gesteinen bestimmt und petrographisch-mineralogische Analysen der darin enthaltenen Olivine und Pyroxene durchgeführt. Wie die Resultate belegen, haben die Magmen bei ihrem Aufstieg durch die Erdkruste insbesondere Material aus der Oberkruste assimiliert und sind zudem durch Fluide aus der abtauchenden Platte beeinflusst worden. Damit konnte gezeigt werden, dass einfache geochemische Methoden allein nicht ausreichen, um die Mantelquelle der Magmen ermitteln oder Aussagen über die Asthenosphärendynamik in der Region machen zu können. Im Gegensatz dazu zeigen die Messungen der Edelgasisotopenverhältnisse in den Fluideinschlüssen der Olivine und Pyroxene, dass deren Edelgaszusammensetzung nicht durch Krustenkontamination beeinflusst wurde, weil die Magmen erst nach der Olivin- bzw. Pyroxen-Kristallisation Schmelzen aus der Oberkruste assimiliert haben. Darüber hinaus konnten durch die Edelgasisotopenmessungen die bisher höchsten magmatischen He- und Ne-Isotopenverhältnisse von ganz Südamerika nachgewiesen werden. Aus der unterschiedlichen Höhe der Messwerte ist zu schließen, dass die im Osten der Puna vorkommenden älteren Laven aus einem nichtkonvektiven (lithosphärischen) Mantel stammen, während die am vulkanischen Bogen und Westrand der Puna gelegenen jüngeren Laven, ihren Ursprung in einer konvektiven (asthenosphärischen) Mantelquelle haben. Zudem konnte gezeigt werden, dass der Mantelgasfluss in der Region in den letzten 5 Millionen Jahren stark zunahm und sich die Eruption von mantelstämmigen basischen Laven in dieser Zeit kontinuierlich in westliche Richtung zum aktiven Vulkanbogen hin verlagerte. Im daraus abgeleiteten Modell beruht dieser Prozess (1) auf einer an die Kontinentalverschiebung gekoppelten W-Drift des Kontinents und (2) auf einem mit der Versteilung der Unterplatte verbundenen Vordringen des subkontinentalen asthenosphärischen Mantels nach W, nach dem Ende der Subduktion des unterseeischen aseismischen Juan Fernández-Rückens in der Region. Zudem gibt es starke Argumente dafür, dass die asthenosphärischen Magmen aus einer fluidreichen Zone in 500 – 600 km Tiefe parallel zur subduzierten Platte aufsteigen und nicht, wie bisher angenommen, durch Schmelzbildung in Bereichen unter 200 km Tiefe, allein durch Entwässerung der abtauchenden Platte erzeugt werden. Zu diesem Resultat führt vor allem die Kombination der He-Isotopenverhältnisse mit Ergebnissen seismologischer Untersuchungen. / This study has determined the concentrations and isotopic composition of noble gases in water and gas samples from thermal springs and in samples of post Miocene basic volcanic rocks from the central Andean Puna Plateau (NW Argentina). The aim of this study is to shed light on questions related to the Neogene subduction history, the geochemical relationship between the oceanic and continental plate and on the distribution of noble gases in mantle-derived rocks of the Central Andes. The results of the geothermal water study show that the Puna plateau has higher values of mantle-derived He between 22° and 26° S compared to the neighbouring Western and Eastern Cordilleras. The highest 3He/4He ratio (5,4 Ra) was obtained close to the Tuzgle volcano, and this is rather high for back-arc gases considering they have ascended through a relatively thick 65 km crust, enriched in crustal 4He. In some cases it was also possible to detect the presence of mantle-derived Ne, which has so far only been demonstrated in a few locations around the world, because of the ubiquitous contamination by atmospheric- and crustal-Ne. Hence, this study clearly demonstrates a higher flux of noble gases from the mantle in the Puna Plateau region than in nearby regions of the Altiplano, the Salta-Rift and the Eastern and Western Cordilleras. In addition to the water study, a series of samples from post Miocene basic volcanic rocks in the Puna back-arc region were analyzed for major, minor and trace element composition as well as Sr, Nd and Pb isotopic ratios. Mineralogical analysis of olivine and pyroxenes from the lavas show that the rocks compositions have signatures that vary depending on the distance from the volcanic arc. Accordingly, magma compositions reflect processes that took place in the subduction-modified mantle wedge and the overlying continental plate. During their ascent, most of the magmas were contaminated with acid crustal melts that mask the geochemical signature of their mantle sources. This makes it difficult to accurately reconstruct the specific geotectonic setting for the magmas and their related mantle sources from the whole rock compositions. However, it is possible to put limits on the origin and amount of contamination from the Pb, Nd and Sr isotopic data. The results show that contaminants are mainly from the upper mantle. Mixing models suggest degrees of crustal assimilation on the order of 10 % and less. Given the problems of interpreting conventional geochemical studies on the origin of the back-arc magmas as just described, the combination of whole rock geochemical results with the corresponding noble gas data is potentially very important. For this purpose, olivine and pyroxene mineral separates mechanically and thermally degassed in order to measure their noble gases content and isotopic ratios. As the results show, the He isotopic signatures in the rocks are quite variable (4,5 - 8,1 Ra), depending on the age and distance to the volcanic arc. Whereas the samples nearest to the arc have MORB-type 3He/4He > 7 Ra, those farthest from the arc have 3He/4He < 7 Ra similar to the typical signature of a subcontinental lithospheric mantle (SCLM). The youngest Puna lavas have the highest primordial 3He/4He ratios and therefore the highest values for mantle-derived He yet found in the whole Andes chain. This implies that the mantle gas flux in the Puna region has increased since the Pliocene while during the same time interval, the focus of back-arc volcanic activity migrated progressively west towards the position of the present volcanic arc. This migration can be correlated with steepening of the subducted slab and advance of the asthenospheric mantle wedge to the west as a consequence of the drift of the Juan Fernández ridge towards the south. A consequence of the westward drift of the subduction zone at ca. 26 km/Ma is the ascent of asthenosphere into the mantle wedge. Geophysical studies suggest that this material ascends parallel to the slab (return flow). The He isotopic signatures from this study show that the asthenospheric ascent was not spacious but took place along certain channels or branches that may relate to deep-reaching weak lithospheric zones but not to a widespread delamination in the SCLM. The isotopic He, Ne and Xe relations of the lava samples collected in the back-arc region far from the volcanic arc indicate the presence of SCLM during back-arc volcanism in this region, which is a grave argument against a crustal delamination. Crustal contamination could not have been responsible for these values as the assimilation of crustal melts essentially took place after the olivine crystallization, as indicated by the variations in Sr- and He-isotope data and the coexistence of quartz and olivine in the samples.

The volatile inventories of the Earth and Moon reflect unique histories of volatile acquisition and loss in the early Solar System. The terrestrial volatile inventory was established after the giant impact phase of accretion, and the planet subsequently settled into a regime of long-term volatile exchange between the mantle and surface reservoirs in association with plate tectonics. Therefore, volatiles in the Earth and Moon shed light on a diverse array of processes that shaped planetary bodies in the Solar System as they evolved to their present-day states. / Earth and Planetary Sciences

The interaction of intense laser pulses with nanometer scale atomic clusters has been an active area of study since the advent of amplified femtosecond lasers. In the case of infrared irradiation of noble gas clusters, direct field-driven ionization results in the ejection of energetic electrons, high ion charge states, and Coulomb explosion of the ion core of the clusters. These processes result from electron motion driven by the cluster potential and the large ponderomotive potential of the laser field. When extreme ultraviolet (XUV) pulses interact with clusters, the mechanisms responsible for the infrared response are 'turned off' because the ponderomotive potential is very small. We have conducted cluster experiments at 38nm using focused XUV pulses produced by high harmonic generation with a 15TW Ti:Sapphire laser. We measured the charge states and kinetic energy spectra of ions produced in the interaction, and observe substantial ion population up to Xe⁵⁺, with a small number of Xe⁶⁺-Xe⁸⁺ ions produced by collisional ionization by hot plasma electrons. The ion kinetic energy spectrum indicates a hydrodynamic expansion at an ion temperature of 8eV. This is in stark contrast to intense infrared/cluster interactions, where clusters are stripped of electrons to a large degree and expand by Coulomb forces, resulting in far higher ion kinetic energy for similar degrees of ionization. / text

Carbon capture and sequestration are considered to be a temporary fix to the climate change global crisis. Following the noble gas tracers injection field experiment at Salt Creek in the state of Wyoming, USA, these tracers may be used to characterise the reservoir as a potential geological sequestration site for carbon dioxide. This study aims to investigate various thermodynamics properties of the five noble gases (Xe, Kr, Ar, Ne, and He) in n-decane at reservoir conditions (340 K – 460 K and 10 MPa – 200 MPa). The study utilises the SKS force field to describe n-decane and both Gibbs Ensemble Monte Carlo and molecular dynamics simulations were used to investigate the solubility, diffusivity, and vapour-liquid equilibrium of the five binary mixtures. The size of the noble gases was found to be important in these nonpolar mixtures where typical interactions are weak and short-ranged. The enthalpies of solvation were calculated and found to be directly correlated to the size of the solute where the energy required for the formation of a cavity to accommodate the solute is compensated by the nature of the intermolecular interaction between solvent and solute. The mixture of Ar + n-decane is of interest particularly because the sigma value for Ar is very similar to that of the CH3 group, resulting in the overall non-mononicity of several thermodynamics properties. Additionally, maxima in enthalpies of solvation were observed in Xe and Kr in n-decane solution at 200 MPa. While these maxima were observed in two different species at similar conditions, they are accommodated by unusually high uncertainties - further investigation is required before definitive conclusions can be drawn. The results from the vapour-liquid equilibrium study of the five noble gas + n-decane binary mixtures were in good agreement with the Peng-Robinson equation of state predictions. What is more, the diffusion coefficient ratios amongst the five noble gases in n-decane were investigated in light of Stoke-Einstein’s relation and Enskog’s hard-sphere relation. Three different radii of solute-solvent interaction were investigated and the best fit was observed when R =radius of solute + radius of gyration of n-decane. Additionally, the diffusion coefficients were utilised in the reservoir simulation to investigate the role of diffusion within the reservoir.

Noble gas partitioning between supercritical CO2-H2O phases can be used to monitor Carbon Capture and Storage (CCS) sites and their natural analogues. However, in order for viable application, noble gas partitioning within these environments must be well constrained. Present estimates of partition coefficient for these systems are taken from the low pressure pure noble gas-water experiments of Crovetto et al. and Smith (Crovetto et al., 1982; Smith, 1985). The effect a supercritical CO2 phase may have on noble gas partitioning is assumed negligible, although this has not been empirically verified. In this work this assumption of noble gas behaviour within a supercritical CO2-H2O binary phase system is evaluated using a combined approach of experiment and simulation. Using a specially commissioned high pressure system at the British Geological Survey paired CO2 and H2O samples were collected from noble gas-enriched systems at pressures and temperatures ranging between 90 – 140 bar and 323.15 – 373.15 K. These were analysed for their noble gas content using a quadrupole mass spectrometer system developed specifically for this project. By comparing the relative concentrations of noble gases in each phase partition coefficients were defined for the experimental conditions. These were compared to their low pressure analogues. At higher CO2 densities all noble gases expressed a significant deviation from predicted partition coefficients. At the highest density (656 kg/m3) helium values decreased by -54% (i.e. reduced solubility within CO2) while argon, krypton and xenon values increased by 76%, 106% and 291% respectively. These deviations are due to supercritical CO2 acting as a polar solvent, the solvation power of which increases as a function of density. Polarisation is induced in each noble gas within this solvent based on their respective polarisabilities. Hence xenon, krypton and argon become more easily solvated as a function of CO2 density while solvating helium becomes harder. These deviation trends are well described using a second order polynomial. This fit defines a deviation coefficient which can be used to adapt low pressure partition coefficients to allow accurate predictions of partitioning within highly dense CO2 phases. Concurrently a Gibbs Ensemble Monte Carlo (GEMC) molecular model was iteratively developed to reproduce noble gas behaviour within these experimental systems. By optimising noble gas-water interactions a pure noble gas-water system was constructed for each noble gas at low pressure which replicated published partition coefficients. These optimised interactions were subsequently applied to low pressure CO2-H2O systems where partition coefficients were derived by calculating excess chemical potentials of noble gases in each phase. Again a good agreement was observed with published values. When the model was applied to the experimental conditions however, a poor agreement with the experimental values was observed. Instead simulated values replicated the low pressure Crovetto et al. and Smith datasets (Crovetto et al., 1982; Smith, 1985). This was due to no CO2-noble gas polarisation terms being included in the current iteration of the model. By including this within the model in the future a full reconciliation between the datasets is expected.

This thesis extends our fundamental knowledge in the area of high oxidation state chemistry of xenon trioxide, XeO3. Oxygen coordination to the Xe(VI) atom of XeO3 was observed in its adducts with triphenylphosphine oxide, [(C6H5)3PO]2XeO3, dimethylsulfoxide, [(CH3)2SO]3(XeO3)2, pyridine-N-oxide, (C5H5NO)3(XeO3)2, and acetone, [(CH3)2CO]3XeO3. The crystalline adducts were characterized by low-temperature single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO3, which detonates when mechanically or thermally shocked, the solid [(C6H5)3PO]2XeO3, [(CH3)2SO]3(XeO3)2, and (C5H5NO)3(XeO3)2 adducts are insensitive to mechanical shock, but undergo deflagration when exposed to a flame. Both [(C6H5)3PO]2XeO3 and (C5H5NO)3(XeO3)2 are air-stable at room temperature. The xenon coordination sphere in [(C6H5)3PO]2XeO3 is a distorted square pyramid and provides the first example of a five-coordinate Xe center in a XeO3 adduct. The xenon coordination sphere of the remaining adducts are distorted octahedral comprised of three equivalent Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO3. Hirshfeld surfaces of XeO3 and (C6H5)3PO in [(C6H5)3PO]2XeO3 show the adduct is well-isolated in its crystal structure and provide a visual representation of the secondary Xe---O bonding in this adduct. Crown ethers have been known for over 50 years, but no example of a complex between a noble-gas compound and a crown ether or another polydentate ligand had been reported. Xenon trioxide is shown to react with 15-crown-5 to form the kinetically stable (CH2CH2O)5XeO3 adduct which, in marked contrast with solid XeO3, does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO3. The gas-phase Wiberg bond valences and indices and empirical bond valences indicate the Xe---Ocrown bonds are predominantly electrostatic, σ-hole, bonds. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO3 and 15-crown-5 in (CH2CH2O)5XeO3 and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO3 and (CH2CH2O)5 reveal regions of negative EP on the oxygen atoms of (CH2CH2O)5 and regions of high positive EP on the xenon atom that are also consistent with σ-hole bonding. Reactions of crown ethers with HF acidified aqueous solutions of XeO3 at room-temperature yielded adducts of 12-crown-4, (CH2CH2O)4XeO3, and 18-crown-6, [(CH2CH2O)6XeO3∙2H2O]2∙HF, whereas slow cooling of a solution of XeO3 with 18-crown-6 in acetone yielded (CH2CH2O)6XeO3∙2H2O. The adducts (CH2CH2O)4XeO3 and (CH2CH2O)6XeO3∙2H2O are shock-insensitive whereas the former adduct is air-stable at room temperature. The low-temperature, single-crystal X-ray structures show the Xe atom of XeO3 coordinated to the oxygen atoms of the crown ether ring. Uncharacteristic xenon coordination numbers exceeding six (including the three primary bonds of XeO3) were observed for all crown ether adducts. Raman spectroscopy frequency shifts are consistent with complex formation and provided evidence for the 2,2,1-cryptand adduct of XeO3. Gas-phase Wiberg bond valences and indices and empirical solid-state bond valences confirmed the electrostatic nature of the Xe---O bonding interactions. Comparisons between the XeO3 and SbF3 18-crown-6, 15-crown-5, and 12-crown-4 complexes are made. Incorporation of xenon trioxide, XeO3, into inorganic polyatomic salts under ambient conditions has been observed in several mixed xenate salts; K[XeO3XO3] (X = Cl, Br), K2[XeO3SeO4]∙HF, K[(XeO3)nZO3] (Z = I, N), and M2[(XeO3)nCO3]∙xH2O (M = Na, K, Rb, Ba). Raman spectroscopy was used to identify the aforementioned compounds and K[XeO3ClO3], K[XeO3BrO3], K2[XeO3SeO4]∙HF, and Rb2[(XeO3)2CO3]∙2H2O were also characterized by low-temperature, single-crystal X-ray diffraction. The xenon atom of XeO3 is seven coordinate in K[XeO3ClO3] and six coordinate in all other compounds with Xe---O distances that are significantly less than the sum of the Xe and O van der Waals radii. These salts provide examples of XeO3 coordinated to inorganic compounds and may provide insights into the inclusion of xenon oxides in minerals. / Thesis / Master of Science (MSc)

No description available.

In der vorliegenden Arbeit werden anhand der Edelgaszusammensetzung von Kimberliten und Lamproiten sowie ihrer gesteinsbildenden Minerale die Wechselwirkungen dieser Gesteine mit Fluiden diskutiert. Die untersuchten Proben stammen vom östlichen Baltischen Schild, vom Kola-Kraton (Poria Guba und Kandalaksha) und vom karelischen Kraton (Kostamuksha). Edelgasanalysen nach thermischer oder mechanischer Gasextraktion von 23 Gesamtgesteinsproben und 15 Mineralseparaten ergeben folgendes Bild: Helium- und Neon-Isotopendaten der Fluideinschlüsse von Lamproiten aus Kostamuksha lassen auf den Einfluss einer fluiden Phase krustaler Herkunft schliessen. Diese Wechselwirkungen fanden wahrscheinlich schon während des Magmenaufstiegs statt, denn spätere Einflüsse krustaler Fluide auf die Lamproite und ihr Nebengestein (Quarzit) sind gering, wie anhand der C/³⁶Ar-Zusammensetzung gezeigt wird. Auch sind die mit verschiedenen Datierungsmethoden (Rb-Sr, Sm-Nd, K-Ar) an Mineralseparaten und teilweise an Gesamtgestein ermittelten Alter konsistent und machen eine metamorphe Überprägung unwahrscheinlich. Aufgrund der Verteilung der primordialen Edelgasisotope zwischen Fluideinschlüssen und Gesteinsmatrix ist ein langsamer Magmenaufstieg anzunehmen, was die Möglichkeit der Kontamination mit einem krustalen Fluid während des Magmenaufstiegs erhöht.<br /> <br>Die Gasextraktion aus Mineralseparaten erfolgte thermisch, wodurch eine Freisetzung der Gase ausschließlich aus Fluideinschlüssen nicht möglich ist. Hierbei zeigen Amphibol und Klinopyroxen, separiert aus Kostamuksha-Lamproiten, in ihrer Neon-Isotopenzusammensetzung im Vergleich zur krustalen Zusammensetzung (Kennedy et al., 1990) ein leicht erhöhtes Verhältnis von ²⁰Ne/²²Ne, was ein Hinweis auf Mantel-Neon sein könnte. Kalifeldspäte, Quarz und Karbonate enthalten dagegen nur Neon krustaler Zusammensetzung. Phlogopite haben sehr kleine Verhältnisse von ²⁰Ne/²²Ne und ²¹Ne/²²Ne, zurückzuführen auf in-situ-Produktion von ²²Ne in Folge von U- und Th-Zerfallsprozessen.<br><br /> Wie unterschiedliche thermische Entgasungsmuster für ⁴⁰Ar und ³⁶Ar zeigen, ist ³⁶Ar in Fluideinschlüssen konzentriert. Das ⁴⁰Ar/³⁶Ar-Isotopenverhältnis der Fluideinschlüsse von Lamproiten aus Kostamuksha ist antikorreliert mit der durch thermische Extraktion bestimmten Gesamtmenge an ³⁶Ar. Argon aus Fluideinschlüssen setzt sich daher aus zwei Komponenten zusammen: Einer Komponente mit atmosphärischer Argon-Isotopenzusammensetzung und einer krustalen Komponente mit einem Isotopenverhältnis ⁴⁰Ar/³⁶Ar > 6000. Diffusion von radiogenem ⁴⁰Ar aus der Kristallmatrix in die Fluideinschlüsse spielt keine wesentliche Rolle.<br /> <br>Kimberlite aus Poria Guba und Kandalaksha zeigen anhand der Helium- und z. T. auch der Neon-Isotopenzusammensetzung eine Mantelkomponente in den Fluideinschlüssen an. Bei einem angenommenen ²⁰Ne/²²Ne-Isotopenverhältnis von 12,5 in der Mantelquelle ergibt sich ein ²¹Ne/²²Ne-Isotopenverhältnis von 0,073 ± 0,011 sowie ein ³He/⁴He-Isotopenverhältnis, welches im Vergleich zum subkontinentalem Mantel (Dunai und Baur, 1995) stärker radiogen geprägt ist. Solche Isotopensignaturen sind mit höheren Konzentrationen an Uran und Thorium in der Mantelquelle der Kimberlite zu erklären.<br /> <br>Rb-Sr- und Sm-Nd-Altersbestimmungen erfolgten von russischer Seite (Belyatskii et al., 1997; Nikitina et al., 1999) und ergeben ein Alter von 1,23 Ga für den Lamproitvulkanismus in Kostamuksha. Eigene K-Ar-Datierungen an Phlogopiten und Kalifeldspäten stimmen mit einem Alter von 1193 ± 20 Ma fast mit den Rb-Sr- und Sm-Nd-Altern überein. Die K-Ar-Datierung an einem Phlogopit aus Poria Guba, separiert aus dem Kimberlit PGK 12a, ergibt ein Alter von 396 Ma, ebenfalls in guter Übereinstimmung mit Rb-Sr-und Sm-Nd-Altern (ca. 400 Ma, Lokhov, pers. Mitteilung). K-Ar-Altersbestimmungen an Gesamtgestein aus Poria Guba erbrachten kein schlüssiges Alter. Die Rb-Sr- und Sm-Nd-Alter des Lamproitmagmatismus in Poria Guba betragen 1,72 Ga (Nikitina et al., 1999).<br /> <br>Vergleiche von gemessenen mit berechneten Edelgaskonzentrationen aus in-situ-Produktion zeigen weiterhin, dass in Abhängigkeit vom Alter der Probe Diffusionsprozesse stattgefunden haben, die zu unterschiedlichen und z. T. erheblichen Verlusten an Helium und Neon führten. Diffusionsverluste an Argon sind dagegen kaum signifikant. Unterschiedliche Diffusionsverluste in Abhängigkeit von Alter und betrachtetem Edelgas zeigen auch die primordialen Edelgase. / In the present thesis, interactions of kimberlites and lamproites as well as their constituent minerals with fluids are discussed based on noble gas compositions. The samples originate from the eastern Baltic Shield, more specifically from the Kola craton (Poria Guba and Kandalaksha) and the Karelia craton (Kostamuksha). Gas was extracted by stepwise heating and crushing from 23 whole rock samples and 15 mineral separates. These two techniques allow differential extraction of gas from fluid inclusions (crushing technique) and from the bulk sample (stepwise heating). The noble gas analyses provide the following information:</P> <P>Helium and neon isotopic compositions of fluid inclusions in lamproites reveal the presence of a crustal fluid phase. Fluid interaction probably ocurred already during the process of magma ascent. Interaction after lamproite emplacement seems unlikely. The lamproites and their host rock differ in the degree of fluid-rock interaction, as demonstrated by the C/³⁶Ar composition. In addition, various dating methods (Rb-Sr, Sm-Nd, K-Ar) yield almost the same age within analytical error. Thus, a metamorphic overprint can be excluded. The distribution of primordial noble gases between fluid inclusions and crystal lattice suggests a relatively slow magma ascent, making an interaction of the lamproitic magma with crustal fluids even more likely. Since noble gases from mineral separates were extracted only by the stepwise heating method, gases stored in fluid inclusions could not be released separately.</P> <P>Amphibole and clinopyroxene separates yielded a higher ²⁰Ne/²²Ne ratio in comparison to crustal composition (Kennedy et al., 1990). This presumably is an indication of a mantle derived fluid phase. On the other hand, neon isotopic composition of K-feldspar, quartz and carbonate separates are indistinguishable from the crustal composition. In comparison to other mineral separates, phlogopite yields very low ratios of ²⁰Ne/²²Ne and ²¹Ne/²²Ne due to in situ production of ²²Ne, which is a result of nuclear reactions.</P> <P>The distinct thermal gas release patterns of ⁴⁰Ar and ³⁶Ar indicates that ³⁶Ar is concentrated in fluid inclusions. The ⁴⁰Ar/³⁶Ar isotopic ratio in fluid inclusions shows a negative correlation with the total amount of ³⁶Ar released by thermal extraction. Therefore, argon from fluid inclusions is a simple 2-component mixture of air and a crustal component with an ⁴⁰Ar/³⁶Ar ratio > 6000. It can be shown that diffusion of ⁴⁰Ar from the matrix into fluid inclusions is negligible.</P> <P>In contrast to lamproites, whole rock kimberlite samples from Poria Guba and Kandalaksha show clear evidence in helium and, to a certain extentalso in neon isotope ratios, of interaction with a mantle derived fluid phase. Assuming a ²⁰Ne/²²Ne ratio of 12.5 for the mantle endmember, a ²¹Ne/²² Ne ratio of 0.073 ± 0.011 can be calculated. Likewise, the resulting ³He/⁴He ratio is more strongly influenced by radiogenic helium in comparison to the mean subcontinental mantle (Dunai und Baur, 1995). Such behaviour reflects higher concentrations of uranium and thorium in the magma source of kimberlites than the subcontinental mantle.</P> <P>Rb-Sr and Sm-Nd age determinations (Belyatskii et al., 1997; Nikitina et al., 1999) yield 1.23 Ga for the lamproite magmatism in Kostamuksha. K-Ar dating of phlogopite and K-feldspar provides similar ages (1.19 Ga). K-Ar dating of a single phlogopite separate from the Kimberlite sample PGK12a from Poria Guba, yields an age of 396 Ma which corresponds well with Rb-Sr and Sm-Nd ages.</P> <P>Depending on sample age, distinct and partly extensive diffusive loss of helium and neon has occurred, as shown by comparison of measured and calculated concentrations of in situ produced isotopes. Diffusion loss is negligible for argon. This is also strongly supported by primordial noble gas composition.