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A new cathodoluminescence-microscope has been developed with a considerably improved detection limit. Time-dependent luminescence intensity changes observed during electron bombardment enabled the recognition of short-lived, long-lived, and brown luminescence colour types in ~-quartz.Short-rived bottle-green or blue luminescence colours with zones of non-luminescing bands are very common in authigenic quartz overgrowths, fracture fillings or idiomorphic vein crystals. Dark brown, short-lived yellow or pink colours are often found in quartz replacing sulphate minerals. Quartz from tectonically active regions commonly exhibits a brown luminescence colour. A red luminescence colour is typical for quartz crystallized close to a volcanic dyke or sill.The causes of these different and previously poorly understood luminescence colours were investigated using heat treatment, electron bombardment and electrodiffusion. Both natural and induced brown luminescence colours reflect the presence of lattice defects (nonbonding Si-O) due to twinning, mechanical deformation, particle bombardment or extremely rapid growth. The bottle-green and blue linearly polarized luminescence colour, characterized by a plane of polarization parallel to the c-axis, both depend on the presence of interstitial cations. The yellow and red luminescence colours in ~-quartz both exhibit a plane of polarization perpendicular to the c-axis and appear to be related to the presence of trace elements in an oxidizing solution and to ferric iron respectively.

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Quantitative analysis of gases by Raman spectroscopy is based on relative Raman scattering cross-sections (RRSCS) and the evolution of different spectral parameters (peak position, peak area, peak intensity, etc.). However, most of the calibration data were established at low pressure (low density) and without evaluating the effect of the composition. Using these data may lead to considerable errors, especially when applied to gas mixtures at high pressure as found in natural fluid inclusions. The aim of this study is to reevaluate the RRSCS of CO2 and to establish new calibration data based on the variation of CO2 Fermi diad splitting as a function of pressure (density) and composition over a pressure range of 5 to 600 bars at 22 and 32 °C. A high-pressure optical cell system (HPOC) and a heating-cooling stage were used for Raman in-situ analyses at controlled PTX conditions. Our experimental results show that the RRSCS of CO2 varies slightly with pressure but can be considered constant over the studied pressure range. It can be used to measure the proportion of CO2 in gas mixtures with an uncertainty of about ± 0.5 mol%. Different polynomial equations were provided to calculate pressure and density of CO2-N2 gas mixtures with an uncertainty of ± 20 bar or 0.01 g.cm −3. A comparison of PVTX properties of natural CO2-N2 fluid inclusions hosted in quartz from the Central Alps (Switzerland) obtained by Raman measurement and as derived from phase transition temperatures by microthermometry experiments shows comparable values. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Detailed uncertainty calculations and the coefficients of regression polynomial equations 3, 4 and 5 (PDF)

Th‐Pb age dating of zoned hydrothermal monazite from alpine‐type fissures/clefts is a powerful tool for constraining polyphase deformation at temperatures below 350°C and presents an alternative to K/Ar and 40Ar/39Ar dating techniques for dating brittle tectonics. This study considers the relationship between cleft orientations in ductile shear zones and cleft mineral crystallization during subsequent brittle overprinting. In the Grimsel area, located in the Aar Massif of the Central Alps, horizontal clefts formed during a primary thrust dominated deformation, while younger and vertically oriented clefts developed during secondary strike‐slip movements. The change is due to a switch in orientation between the principal stress axes σ2 and σ3. The transition is associated with monazite crystallization and chloritization of biotite at around 11.5 Ma. Quartz fluid inclusion data allow a link between deformation stages and temperatures to be established and indicate that primary monazite crystallization occurred in both cleft systems at 300–350°C. While cleft monazite crystallization ceases at ~11 Ma in inactive shear zones, monazite growth, and/or dissolution‐reprecipitation continues under brittle deformation conditions in vertical clefts during later deformation until ~7 Ma. This younger shear zone activity occurs in association with dextral strike‐slip movement of the Rhone‐Simplon fault system. With the exception of varying Th/U values correlated with the degree of oxidation, there is only limited compositional variation in the studied cleft monazites.

L'étude des inclusions fluides des cristaux de quartz syncinématiques donne un éclairage nouveau sur la composition des fluides et la distribution des températures et des pressions dans la région externe des Alpes centrales. A partir de la densité du méthane et des températures minimales de formation, les inclusions fluides des systèmes CH4-H2O et CH4 ont été utilisées comme thermomètres et baromètres. Les conclusions suivantes peuvent être tirées à l'échelle régionale : 1. Les fluides piégés dans les inclusions définissent des zones dont la composition varie suivant les zones métamorphiques : — zone non métamorphique : > 1 mole % hydrocarbures plus lourds que le méthane, CH4, H2O, CO2,... — anchizone supérieure et moyenne : CH4, < x mole % hvdrocarbures plus lourds que le méthane H2O, CO2, ... — anchizone profonde et épizone : H2O, CO2, ... 2. Les conditions minimales de formation des fentes à minéraux et de leurs cristaux de quartz sont pour l'anchizone supérieure et moyenne : 200-270° C — 1 200-1 700 bars, avec des gradients géothermiques de 25-45° C/km. 3. A partir de l'étude des inclusions fluides, les conditions minimales de température et pression suivantes ont été trouvées pour le métamorphisme : — transition entre zone non métamorphique et anchizone supérieure : T > 200° C — P > 1 200 bars — transition entre anchizone moyenne et anchizone profonde : T > 270° C — P > 1 700 bars 4. L'évolution des fluides est un produit du métamorphisme progressif. Les fluides ont été piégés dans les cristaux de quartz à. la fin du charriage des nappes et durant la surrection des Alpes (Miocène moyen à terminal). Comme des unités tectoniques contenant des fluides de métamorphisme plus intense se trouvent au-dessus d'unités tectoniques contenant des fluides de métamorphisme plus faible, on en déduit que le métamorphisme des unités transportées s'est produit avant la mise en place finale des nappes.