1,721,042 research outputs found
Quartz chemistry in polygeneration Sveconorwegian pegmatites, Froland, Norway
No full textElement concentrations in quartz, feldspar and biotite of Sveconorwegian (1.13-0.9 Ga) granitic pegmatites in Froland, Norway, were analysed by LA-lCP-MS, EPMA and XRF, respectively, in order to determine chemical variations between different pegmatite types and within individual pegmatitic bodies. A refined classification of the syn-, late- and post-orogenic granitic pegmatites of Froland is presented basing on the pegmatite structure, bulk composition and mineral chemistry. Syn-orogenic pegmatites (1.13-1.06 Ga) are relative primitive with respect to granite differentiation. Late-orogenic pegmatites linked to the Herefoss pluton (0.93 Ga) have the most primitive composition and contain Fe phlogopite. Post-orogenic zinnwaldite pegmatites (< 0.93 Ga) are the most evolved. Pegmatitic quartz has an astonishingly consistent trace element signature between and within syn-orogenic pegmatites. Average concentrations are in the range of 6-10 mu gg(-1) for Li, 34-44 mu gg(-1) for Al, 4-8 mu gg(-1) for Ti, and 0.9-1.8 mu gg(-1) for Ge, Al, Li, Fe, Ge, and Ti in quartz of late- and post-orogenic and contact-metamorphosed syn-orogenic pegmatites are more variable. Micro-mylonitisation and contact metamorphism caused the lowering of Li and Al and the increase of Ti and Ge in pegmatitic quartz of some syn-orogenic granites. Several generations of secondary quartz replaced pegmatitic quartz at the micro scale (< 1 mm) during retrograde fluid-driven overprint. Secondary quartz is depleted in Al, Ti and Li compared to the host quartz. In contrast to quartz, the feldspar and biotite chemistry depends largely on the differentiation degree of the pegmatites and varies significantly within structurally-zoned pegmatite bodies. Feldspar and biotite chemistry reflects changes in melt composition within pegmatites, which includes a decrease of Mg and Sr and increase of Li, Rb, and Ba. The syn-orogenic pegmatites were formed during the crustal accretion on the western margin of Fennoscandia under constant PTX-conditions causing the homogeneous trace element signature of quartz
Raman spectroscopy of synthetic (Mg,Fe)SiO3 single crystals. An analytical tool for natural orthopyroxenes
No full textSingle crystals of synthetic orthopyroxene were analyzed by Raman spectroscopy and electron microprobe in order to calibrate the effect of chemical composition on the position of Raman bands. For the Raman peak close to 670 cm(-1) we obtain the correlations between Raman shift (RS) and chemical composition FeO(wt%) = - 1.998 . RS(cm (1)) + 1373.2 and MgO(wt%) = 1.4537. RS(cm (-1)) - 959.02, allowing the determination of FeO with an accuracy of +/- 0.4 wt% and MgO with an accuracy of +/- 0.3 wt%, corresponding to less than 1 mole% ferrosilite or enstatite. A test of this calibration using natural orthopyroxene crystals shows larger deviations up to 3 wt%. These deviations can mainly be related to significant amounts of CaO and Al2O3, leading to an overestimation of FeO or MgO, respectively
DATA ON 61 CHEMICAL ELEMENTS FOR THE CHARACTERIZATION OF THREE MAJOR GLASS COMPOSITIONS IN LATE ANTIQUITY AND THE MIDDLE AGES
No full textSets of 20 soda ash, 16 soda lime and 23 wood ash glasses mainly from excavations in Europe were analysed by microprobe and LA-ICP-MS for 61 elements and are presented as average concentrations with standard deviations. Concentrations of sodium, potassium and magnesium allow the major glass type to be identified. Specific compositions of the raw materials of glass production indicate certain sources, technical processes and ages. Heavy minerals etc. of quartz sands contain rare earth elements (REE) from crustal fractionations that are different for the three major glass types. Accumulations of P, B, Ba, Mn and K in wood from soils by organic processes can characterize glass from certain regions
Viscosity of soda-lime glass and potash-based glass of the Carolingian period (8th – 9th century CE)
No full textThe mosaics of the Cappella Palatina in Palermo (CPP), Sicily; Scientific chemical investigations
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Anorthite-calibrated backscattered electron profiles, trace elements, and growth textures in feldspars from the Teide-Pico Viejo volcanic complex (Tenerife)
No full textMagma chamber dynamics at the phonolitic to basanitic Teide-Pico Viejo volcanic complex on Tenerife, Canary Islands, have been investigated using feldspar zonation and chemistry. Backscattered electron-image grey value profiles, obtained by electron microprobe and calibrated on anorthite content, allow the investigation of much better spatially resolved zonation profiles than quantitative point analysis alone. On the basis of these zonation patterns and trace element analyses by electron microprobe, magma chamber processes such as magma recharge and mingling, as well as whole-chamber overturn events, can be identified and characterized in more detail. Samples from all investigated eruption centres contain feldspars, which have experienced growth in a deep reservoir, followed by ascent, resorption, and growth of mantles in more shallow levels in the crust just prior to eruption. Two Pico Viejo samples exhibit feldspars with a characteristic drop in anorthite content, which is not accompanied by resorption. Trace element behaviour in these samples shows that cores and mantles have grown from the same magma reservoir: The conclusion from these data is that there occurred complete overturn events in layered magma chambers, presumably induced by cold plumes from the cupola layers. A mass balance calculation shows that the proportions of the layers are similar to 75 wt.% lower part and similar to 25 wt.% cupola layer. Correlations between zonation patterns of single crystals in different rocks show that the Teide magma chambers are larger and chemically buffered compared with the smaller Pico Viejo system. Feldspars from Pico Viejo exhibit rather complex anorthite-profiles and more frequently display disturbances likely to be caused by arrival of new magma batches. (c) 2006 Elsevier B.V. All rights reserved
Release of zirconia nanoparticles at the metal stem-bone cement interface in implant loosening of total hip replacements
No full textIn a previous failure analysis performed on femoral components of cemented total hip replacements, we determined high volumes of abraded bone cement. Here, we describe the topography of the polished surface of polymethyl methacrylate (PMMA) bone cement containing zirconia radiopacifier, analyzed by scanning electron microscopy and vertical scanning interferometry. Zirconia spikes protruded about 300 nm from the PMMA matrix, with pits of former crystal deposition measuring about 400 nm in depth. We deduced that the characteristically mulberry-shaped agglomerates of zirconia crystals are ground and truncated into flat surfaces and finally torn out of the PMMA matrix. Additionally, evaluation of in vitro PMMA-on-PMMA articulation confirmed that crystal agglomerations of zirconia were exposed to grain pullout, fatigue, and abrasion. In great quantities, micron-sized PMMA wear and zirconia nanoparticles accumulate in the cement-bone interface and capsular tissues, thereby contributing to osteolysis. Dissemination of nanoparticles to distant lymph nodes and organs of storage has been reported. As sufficient information is lacking, foreign body reactions to accumulated nanosized zirconia in places of long-term storage should be investigated. Statement of Significance The production of wear particles of PMMA bone cement in the interface to joint replacement devices, presents a local challenge. The presence of zirconia particles results in frustrated digestion attempts by macrophages, liberation of inflammatory mediators, and necrosis leading to aseptic inflammation and osteolyses. Attempts to minimize wear of articulating joints reduced the attention to the deterioration of cement cuffs. We therefore investigated polished surfaces of retrieved cuffs to demonstrate their morphology and to measure surface roughness. Industrially admixed agglomerates of the radiopacifier are abraded to micron and nano-meter sized particles. The dissemination of zirconia particles in the reticulo-endothelial system to storage organs is a possible burden. Research to replace the actual contrast media by non-particulate material deserves more attention. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Deciphering fluid inclusions in high-grade rocks
No full textAbstractThe study of fluid inclusions in high-grade rocks is especially challenging as the host minerals have been normally subjected to deformation, recrystallization and fluid-rock interaction so that primary inclusions, formed at the peak of metamorphism are rare. The larger part of the fluid inclusions found in metamorphic minerals is typically modified during uplift. These late processes may strongly disguise the characteristics of the “original” peak metamorphic fluid. A detailed microstructural analysis of the host minerals, notably quartz, is therefore indispensable for a proper interpretation of fluid inclusions. Cathodoluminescence (CL) techniques combined with trace element analysis of quartz (EPMA, LA-ICPMS) have shown to be very helpful in deciphering the rock-fluid evolution. Whereas high-grade metamorphic quartz may have relatively high contents of trace elements like Ti and Al, low-temperature re-equilibrated quartz typically shows reduced trace element concentrations. The resulting microstructures in CL can be basically distinguished in diffusion patterns (along microfractures and grain boundaries), and secondary quartz formed by dissolution-reprecipitation. Most of these textures are formed during retrograde fluid-controlled processes between ca. 220 and 500 °C, i.e. the range of semi-brittle deformation (greenschist-facies) and can be correlated with the fluid inclusions. In this way modified and re-trapped fluids can be identified, even when there are no optical features observed under the microscope
Die Minerale des Kalksteinbruches Oppermann bei Emmenhausen, 10 km westlich von Göttingen
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