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The Cima Lunga unit in the Central Alps is dominated by quartzofeldspathic gneisses with subordinate mafic, ultramafic, and metacarbonate rocks. Only mafic and ultramafic lithologies were thought to preserve clear evidence of Alpine high-P metamorphism. This led to the questions of whether the different rock types were subducted and exhumed as a coherent unit or underwent different pressure���temperature (P���T) histories. New petrological and geochemical data from a metapelite associated with garnet peridotite from Cima di Gagnone (Cima Lunga unit, Switzerland) were obtained using major and trace element mapping. Complex zoning patterns in garnet and white mica are observed. In particular, high Ti content in phengite and increasing P, Zr, and HREE contents in pyrope-rich garnet indicate that this metapelite underwent high-P and high-T (HP���HT) metamorphism involving fluid-fluxed partial melting. A P���T path is reconstructed by combining textural analysis with petrological���geochemical data and thermodynamic simulations. We show that the mineral record preserves an evolution from prograde to HP���HT peak conditions (2.7 �� 0.1 GPa and 800���) followed by near-isobaric cooling (~2.5 GPa and 700���750���) prior to decompression (1.0 GPa and ~620���). The reconstructed P���T path suggests that the studied metapelites were subducted to depths where the slab gets heated by proximity to asthenospheric mantle related to slab break-off. This heating resulted in the dehydration of chlorite-to garnet peridotite and the liberated fluids triggered partial melting in the associated metapelites, which might have favoured the fast exhumation of the entire Cima Lunga unit. Metapelites and garnet peridotite from Cima di Gagnone underwent a common prograde to peak and retrograde P���T path without significant tectonic pressure difference between the different lithologies, and deviation from lithostatic pressure is excluded. Lastly, the peak metamorphic conditions of metapelite from Cima di Gagnone are comparable with P���T estimates of ultramafic lithologies from the southern Adula nappe and the Dascio Bellinzona zone, thus opening new scenarios for the geodynamic interpretation of the Central Alps.

Mutnovsky Volcano, located in Kamchatka, Russia, is a young volcano that has formed a series of four overlapping stratocones over its approximately 80 ka history. Erupted products at Mutnovsky range in composition from basalts to dacites; basalts are the most common. In this study, melt inclusions from representative samples of all erupted compositions from all four eruptive centers were analyzed to investigate the causes of the compositional heterogeneity, melt evolution, and pre-eruptive magma dynamics. Melt inclusions from Mutnovsky were sampled in olivine, plagioclase, orthopyroxene, and clinopyroxene. The melt inclusion data represent a wide range of melt compositions, from basalt through rhyolite. Geochemical modeling of melt inclusion data, combined with field evidence and chemical zoning of plagioclase phenocrysts, indicates that fractional crystallization and magma mixing produced the range of erupted bulk rock compositions. The measured variability of melt inclusion compositions in each host mineral phase indicates that different host minerals trapped unique melts that evolved separately from one another. The melt inclusion data suggest that individual melt portions evolved by fractional crystallization, perhaps in different magma chambers, within the Mutnovsky plumbing system, and were mixed prior to eruption. Our data do not indicate whether the mixing events were the cause of eruption or are simply the manifestation of the eruption process.

An efficient, clean procedure for the measurement of element mass fractions in bulk rock nanoparticulate pressed powder pellets (PPPs) by 193 nm laser ablation ICP-MS is presented. Samples were pulverised by wet milling and pelletised with microcrystalline cellulose as a binder, allowing non-cohesive materials such as quartz or ceramics to be processed. The LA-ICP-MS PPP analytical procedure was optimised and evaluated using six different geological reference materials (JP-1, UB-N, BCR-2, GSP-2, OKUM and MUH-1), with rigorous procedural blank quantification employing synthetic quartz. Measurement trueness of the procedure was equivalent to that achieved by solution ICP-MS and LA-ICPMS analysis of glass. The measurement repeatability was as low as 0.5–2% (1s, n = 6) and, accordingly, PPP homogeneity could be demonstrated. Calibration based on the reference glasses NIST SRM 610, NIST SRM 612, BCR- 2G and GSD-1G revealed matrix effects for glass and PPP measurement with NIST SRM 613; using basalt glasses eliminated this problem. Most significantly, trace elements not commonly measured (flux elements Li, B; chalcophile elements As, Sb, Tl, In, Bi) could be quantified. The PPP-LA-ICP-MS method overcomes common problems and limitations in analytical geochemistry and thus represents an efficient and accurate alternative for bulk rock analysis.

A petrographic investigation revealed polyphase quartz cementation in the Finefrau Sandstone (Upper Carboniferous, Western Germany) and the Solling Sandstone (Lower Triassic, Central Germany). Three different cements could be distinguished in each sandstone based on their cathodoluminescence and trace element composition. The first quartz generation is suggested to have been formed during eogenesis due to dissolution and replacement of feldspar. The mesogenetic paragenesis comprises two generations of quartz and illite, which are accompanied by albite in the Solling Sandstone. Sharp luminescence zoning in quartz overgrowths points to distinct episodes of cementation in both sandstones. Significant amounts of Al, Li and H and traces of Ge and B have been detected in the quartz overgrowths. The Al-content of the quartz cements in the Finefrau Sandstones exceeds that in the quartz cements in the Solling Sandstone by a factor of five. It is suggested that this compositional variation reflects the conditions in the pore-water, such as temperature and pH. The Al-concentration is generally correlated to the Li-content with the exception of the latest quartz generation in the Finefrau Sandstones which is also most enriched in trace elements. The ratio of Li/Al varies between 0·11 and 0·25 in the two sandstones. The Li/H-ratio, which ranges from 0·12 to 0·3, is controlled by the activity ratio of Li and H in the pore fluid. Clay minerals are the most important source for Li and high salinities favour the mobilization of Li during diagenesis. Thus, a relatively low salinity and low pH are responsible for the low Li/H-ratio in the Finefrau Sandstone, while high salinity and neutral to alkaline pH results in a high Li/H-ratio for the Solling Sandstone. The Ge-contents are generally near the average of detrital quartz and indicate that pressure dissolution is a major source for quartz cementation. Different chemical compositions of distinct quartz generations indicate changes in the physico-chemical conditions and point to mobilization of silica from different sources (for example, pressure solution and clay mineral transformations).

Molybdenum concentration and δ98/95Mo values for NIST SRM 610 and 612 (solid glass), NIST SRM 3134 (lot 891307; liquid) and IAPSO seawater reference material are presented based on comparative measurements by MC-ICP-MS performed in laboratories at the Universities of Bern and Oxford. NIST SRM 3134 and NIST SRM 610 and 612 were found to have identical and homogeneous 98Mo/95Mo ratios at a test portion mass of 0.02 g. We suggest, therefore, that NIST SRM 3134 should be used as reference for the δ–Mo notation and to employ NIST SRM 610 or 612 as solid silicate secondary measurement standards, in the absence of an isotopically homogeneous solid geological reference material for Mo. The δ98/95MoJMC Bern composition (Johnson Matthey ICP standard solution, lot 602332B as reference) of NIST SRM 3134 was 0.25 ± 0.09‰ (2s). Based on five new values, we determined more precisely the mean open ocean δ98/95MoSRM 3134 value of 2.09 ± 0.07‰, which equals the value of δ98/95MoJMC Bern of 2.34 ± 0.07‰. We also refined the Mo concentration data for NIST SRM 610 to 412 ± 9 μg g−1 (2s) and NIST SRM 612 to 6.4 ± 0.7 μg g−1 by isotope dilution. We propose these concentration data as new working values, which allow for more accurate in situ Mo determination using laser ablation ICP-MS or SIMS.

Orthorhombic Al2O3-rich aluminoborate samples are synthesized by solid state reactions between α-Al2O3 and B2O3 or H3BO3 (Pt crucible, 1100—1200 °C).

Single crystals of the title compound are prepared by sintering mixtures of ZrO2, La2O3, and Li2CO3 using ceramic crucibles in initial steps and later sealed Pt capsules.

Terra Nova, 22, 303–308, 2010 Abstract The nature of uranium source rocks, transport conditions and deposition processes are still highly controversial for world-class unconformity-related U deposits. This article presents the first detailed chemistry of brines associated with the giant McArthur River U deposit, Canada. LA-ICP-MS analysis of individual fluid inclusions suggests mixing between a Na–Ca–Mg–K–Sr–Ba brine and a Ca–Mg–Na–K–Sr–Ba brine. The brines share a common origin (evaporated seawater) and show evidence for contrasting interaction with basement rocks. The Na-rich brine lost Mg and K in alteration haloes around U ores, while the Ca-rich brine results from Na–Ca exchange and Sr–Ba gain. U concentrations (0.3–530 μg g−1) are anomalously high compared with usual basinal fluids, this indicating that U uptake occurred within basement rocks. The two brine end-members have mixed within the main U deposit area, which could be one of the major driving forces for U deposition.

Die weltweit reichsten Quellen von Kupfer, Molybdan, Wolfram, Zinn, und ein wesentlicher Anteil an Gold stammen aus porphyrischen Erzlagerstatten wie die riesige Kupfer-Gold-Mine von Bajo de la Alumbrera in Argentinien. Hier werden Erzreserven von 800 Millionen Tonnen mit Gehalten von rund 0, 6 Gewichtsprozent Kupfer und 0, 6 g/t Gold im Tagebau gewonnen. Vorstellungen zur Bildung dieser Metallvorkommen gehen davon aus, dass in 5—10 Kilometern Tiefe in vulkanisch aktiven Gebieten Magmakammern existieren.