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  • 1
    Monograph available for loan
    Monograph available for loan
    The Role of Halogens in Terrestrial and Extraterrestrial Geochemical Processes : Surface, Crust, and Mantle (2017)
    Cham : Springer International Publishing
    Details Availability
    Call number: 10/M 18.90965 ; M 18.90965
    Description / Table of Contents: The book summarizes the knowledge and experiences concerning the role of halogens during various geochemical processes, such as diagenesis, ore-formation, magma evolution, metasomatism, mineralization, and metamorphism in the crust and mantle of the Earth. It comprises the role of halogens in other terrestrial worlds like volatile-rich asteroids, Mars, and the ice moons of Jupiter and Saturn. Review chapters outline and expand upon the basis of our current understanding regarding how halogens contribute to the geochemical/geophysical evolution and stability of terrestrial worlds overall.
    Type of Medium: Monograph available for loan
    Pages: vi, 1030 Seiten
    Edition: 1st edition 2018
    ISBN: 978-3-319-61665-0
    Series Statement: Springer Geochemistry
    Classification:
    Geochemistry
    Language: English
    Location: Reading room
    Location: Upper compact magazine
    Branch Library: GFZ Library
    Branch Library: GFZ Library
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  • 2
    Electronic Resource
    Electronic Resource
    K-feldspar–quartz and K-feldspar–plagioclase phase boundary interactions in garnet–orthopyroxene gneiss's from the Val Strona di Omegna, Ivrea–Verbano Zone, northern Italy (2000)
    Springer
    Contributions to mineralogy and petrology 140 (2000), S. 148-162 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A detailed study based on textural observations combined with microanalysis [back scattered electron imaging (BSE) and electron microprobe analysis (EMPA)] and microstructural data transmission electron microscopy (TEM) has been made of K-feldspar micro-veins along quartz–plagioclase phase and plagioclase–plagioclase grain boundaries in granulite facies, orthopyroxene–garnet-bearing gneiss's (700–825 °C, 6–8 kbar) from the Val Strona di Omegna, Ivrea–Verbano Zone, northern Italy. The K-feldspar micro-veins are commonly associated with quartz and plagioclase and are not found in quartz absent regions of the thin section. This association appears to represent a localised reaction texture resulting from a common high grade dehydration reaction, namely: amphibole + quartz = orthopyroxene + clinopyroxene + plagioclase + K-feldspar + H2O, which occurred during the granulite facies metamorphism of these rocks. There are a number of lines of evidence for this. These include abundant Ti-rich biotite, which was apparently stable during granulite facies metamorphism, and total lack of amphibole, which apparently was not. Disorder between Al and Si in the K-feldspar indicates crystallisation at temperatures 〉500 °C. Myrmekite and albitic rim intergrowths in the K-feldspar along the K-feldspar–plagioclase interface could only have formed at temperatures 〉500–600 °C. Symplectic intergrowths of albite and Ca-rich plagioclase between these albitic rim intergrowths and plagioclase suggest a high temperature grain boundary reaction, which most likely occurred at the start of decompression in conjunction with a fluid phase. Relatively high dislocation densities (〉2 × 109 to 3 × 109/cm2) in the K-feldspar suggest plastic deformation at temperatures 〉500 °C. We propose that this plastic deformation is linked with the extensional tectonic environment present during the mafic underplating event responsible for the granulite facies metamorphism in these rocks. Lastly, apparently active garnet grain rims associated with side inclusions of K-feldspar and quartz and an exterior K-feldspar micro-vein indicate equilibrium temperatures within 20–30 °C of the peak metamorphic temperatures estimated for the sample (770 °C). Contact between these K-feldspar micro-veins and Fe-Mg silicate minerals, such as garnet, orthopyroxene, clinopyroxene or biotite along the interface, is observed to be very clean with no signs of melt textures or alteration to sheet silicates. This lends support to the idea that these micro-veins did not originate from a melt and, if fluid induced, that the water activity of these fluids must have been relatively low. All of these lines of evidence point to a high grade origin for the K-feldspar micro-veins and support the hypothesis that they formed during the granulite facies metamorphism of the metabasite layers in an extensional tectonic environment as the consequence of localised dehydration reactions involving the breakdown of amphibole in the presence of quartz to orthopyroxene, clinopyroxene, plagioclase, K-feldspar and H2O. It is proposed that the dehydration of the metabasite layers to an orthopyroxene–garnet-bearing gneiss over a 4-km traverse in the upper Val Strona during granulite facies metamorphism was a metasomatic event initiated by the presence of a high-grade, low H2O activity fluid (most likely a NaCl–KCl supercritical brine), related to the magmatic underplating event responsible for the Mafic Formation; and that this dehydration event did not involve partial melting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100000185
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  • 3
    Electronic Resource
    Electronic Resource
    Titaniferous magnetite–ilmenite thermometry and titaniferous magnetite–ilmenite–orthopyroxene–quartz oxygen barometry in granulite facies gneisses, Bamble Sector, SE Norway: implications for the role of high-grade CO2-rich fluids during granulite genesis (2000)
    Springer
    Contributions to mineralogy and petrology 139 (2000), S. 180-197 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Oxygen fugacities have been estimated for a wide distribution of samples from the granulite facies terrane (region C) of the Bamble Sector, SE Norway using both the titaniferous magnetite–ilmenite and orthopyroxene–titaniferous magnetite–quartz oxygen barometers. These oxygen fugacities are estimated using temperatures calculated from the titaniferous magnetite–ilmenite thermometer of Ghiorso and Sack (1991) and are both internally consistent with each other as well with the thermometer. In samples for which the estimated temperature is high, the two oxygen barometers show good agreement whereas agreement is poor for low temperature samples. In these low temperature samples, oxygen fugacities estimated from titaniferous magnetite–ilmenite are considerably less than those estimated from orthopyroxene–titaniferous magnetite–quartz. An increase in this discrepancy with decrease in temperature appears to reflect preferential resetting of the hematite component in the ilmenite grains without significant alteration of the more numerous titaniferous magnetite grains. This is due, in part, to greater re-equilibration of the ilmenite grains during retrograde interoxide resetting between the ilmenite grains and the titaniferous magnetite grains. The mean temperature for the non-reset samples, 791 ± 17 °C (1σ), is in good agreement with temperatures obtained from garnet–orthopyroxene KD exchange thermometry in the same region, 785–795 °C (1σ) (Harlov 1992, 2000a). Most non-reset oxygen fugacities range from log10 f O2=−14 to −11.8 or approximately 0.5–1.5 log units above quartz–fayalite–magnetite at 7.5 kbar. Both these temperatures and the range of oxygen fugacities are in good agreement with those estimated using the titaniferous magnetite–ilmenite thermometer/oxygen barometer of Andersen et al. (1991). The QUIlP equilibrium (quartz–ulvöspinel–ilmenite–pyroxene) is used to project self-consistent equilibrium temperatures and oxygen fugacities for samples reset due to hematite loss from the ilmenite grains. These projected temperatures and oxygen fugacities agree reasonably well with the non-reset samples. The mean projected QUIlP temperature is 823 ± 6 °C (1σ). This result supports the conclusion that low titaniferous magnetite–ilmenite temperatures (down to 489 °C) and accompanying low oxygen fugacities are the result of hematite loss from the ilmenite grains. Non-reset oxygen fugacities lie approximately 1.5 log10 units above the upper graphite stability curve indicating that the stable C–O–H fluid phase interacting with these gneisses, whether regionally or locally, was CO2. This is borne out by the presence of numerous CO2-rich fluid inclusions in these rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007670
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  • 4
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    High‐Grade K‐Feldspar Veining in Granulites From the Ivrea‐Verbano Zone, Northern Italy: Fluid Flow in the Lower Crust and Implications For Granulite Facies Genesis (1998)
    University of Chicago Press
    Details
    Publication Date: 1998-07-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
    Published by University of Chicago Press
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  • 5
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    Comparative Oxygen Barometry in Granulites, Bamble Sector, SE Norway (1992)
    University of Chicago Press
    Details
    Publication Date: 1992-07-01
    Print ISSN: 0022-1376
    Electronic ISSN: 1537-5269
    Topics: Geosciences
    Published by University of Chicago Press
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  • 6
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    Characterization of fluor-chlorapatites by electron probe microanalysis with a focus on time-dependent intensity variation of halogens (2012)
    Mineralogical Society of America
    Details
    Publication Date: 2012-07-01
    Description: Prior research has shown that fluorine and chlorine X-ray count rates vary with exposure to the electron beam during electron probe microanalysis (EPMA) of apatite. Stormer et al. (1993) and Stormer and Pierson (1993) demonstrate that the EPMA-operating conditions affect the halogen intensities in F-rich natural Durango and Wilberforce apatites and in a Cl-rich apatite. Following these studies, we investigated the effects of operating conditions on time-dependent X-ray intensity variations of F and Cl in a broad range of anhydrous fluor-chlorapatites. We tested 7, 10, and 15 kV accelerating voltages; 4, 10, and 15 nA beam currents; 2, 5, and 10 μm diameter fixed spot sizes; and the influence of 2 distinct crystal orientations under the electron beam. We find that the halogen X-ray intensity variations fluctuate strongly with operating conditions and the bulk F and Cl contents of apatite.We determined the optimal EPMA operating conditions for these anhydrous fluor-chlorapatites to be: 10 kV accelerating voltage, 4 nA beam current (measured at the Faraday cup), 10 μm diameter fixed spot, and the apatite crystals oriented with their c-axes perpendicular to the incident electron beam. This EPMA technique was tested on a suite of 19 synthetic anhydrous apatites that covers the fluorapatite-chlorapatite solid-solution series. The results of these analyses are highly accurate; the F and Cl EPMA data agree extremely well with wet-chemical analyses and have an R2 value 〉0.99.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 7
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    A new semi-micro wet chemical method for apatite analysis and its application to the crystal chemistry of fluorapatite-chlorapatite solid solutions (2011)
    Mineralogical Society of America
    Details
    Publication Date: 2011-01-01
    Description: A series of synthetic apatite crystals along the fluorapatite-chlorapatite Ca5(PO4)3(F,Cl) join have been synthesized at 1220 to 1375 {degrees}C from Ca3(PO4)2 dissolved in a CaF2-CaCl2 melt. The solid solutions have then been characterized both chemically and structurally. Because of well-known difficulties in measuring the chemical composition of apatites containing F and Cl by electron microprobe a new semi-micro wet chemical method has been developed. Apatite is relatively well dissolved in mineral acids including HNO3. Nitric acid digestion of apatite for analysis of F and Cl has not been applied in the past to our knowledge. One reason is the potential risk of losing gaseous HF and HCl during acid decomposition. We present an analytical procedure that enables the analyses of F, Cl, Ca, P, and trace elements after digestion of 10 mg apatite with a small amount of 1 N HNO3 in gas-tight PTFE tubes at 80 {degrees}C. Analytical results from three independent closed acid digestions of 20 synthetic fluor-chlorapatites are presented. The reliability of this method was tested on the basis of charge balance, the Ca/P, Ca/(F+Cl), and P/(F+Cl) ratios, and the total cation sum. Independently derived Cl/F ratios by XRD using Rietveld refinement of apatite crystals from the same synthesis experiments are additionally presented. The apatite solid solutions were characterized by IR spectroscopy, X-ray powder diffraction using Rietveld refinements (XRD), and single-crystal diffraction (SCXRD) structure determinations. IR spectra indicate no or only a very minor hydroxylapatite component in the solid solutions. Lattice parameters of the apatite solid solutions vary systematically with composition. The a-lattice parameter varies linearly. In contrast to F-, which occupies a special position at (0,0,1/4) in the unit cell, Cl- occupies split positions ranging from 0.346(4) to 0.4428(2) in the z-coordinate because of the larger ionic Cl- radius. Single-crystal structure determinations reveal that the Ca2 site is also split into Ca2A and Ca2B sites for F- and Cl- as nearest neighbors, respectively. In comparison to the Ca2A-F- arrangements, the larger Cl- ion presses the triangular arrangement of Ca-ions outward to facilitate an energetic more favorable constellation resulting in the formation of Ca2B-Cl- arrangements. The occupancies of the Ca2A and Ca2B sites, as determined by SCXRD, correlate strictly with the F-Cl content. Apatites rich in Cl (xCl 〉 0.5) show a deficiency in halogens, which is probably charge balanced by oxygen (Cl-+Cl- {leftrightarrow} O2-+{square}) forming an oxyapatite component. The oxyapatite component prevents the F-absent, Cl-rich apatite from crystallizing with a monoclinic symmetry and stabilizes the observed hexagonal symmetry.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 8
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    Experimental incorporation of Th into xenotime at middle to lower crustal P-T utilizing alkali-bearing fluids (2012)
    Mineralogical Society of America
    Details
    Publication Date: 2012-04-01
    Description: In this study, a natural Th-absent xenotime [(Y+HREE)PO4], is enriched in specific areas with respect to Th + Si utilizing a series of alkali-bearing fluids that included 2 N NaOH, 2 N KOH, Na2Si2O5 + H2O, and NaF + H2O, in addition to ThO2 and SiO2. Charge and fluid were sealed in Au capsules and placed in the piston-cylinder apparatus (CaF2 assemblies) at 1000 MPa and 900 °C (8 to 25 days) or in cold-seal autoclaves on a hydrothermal line at 500 MPa and 600 °C (23 days). BSE imaging, EMP analysis, and TEM indicate that a fraction of the xenotime grains in the 2 N KOH, Na2Si2O5 + H2O, and NaF + H2O experiments have altered areas enriched in Th + Si. No reaction was observed in the 2 N NaOH experiments. The altered areas occur as a series of curvilinear intergrowths with sharp compositional boundaries that extend from the edge of the xenotime grain into the interior. Formation of these Th + Si enriched areas is interpreted as a consequence of fluid-mediated coupled dissolution-reprecipitation.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 9
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    Experimental determination of stability relations between monazite, fluorapatite, allanite, and REE-epidote as a function of pressure, temperature, and fluid composition (2011)
    Mineralogical Society of America
    Details
    Publication Date: 2011-10-01
    Description: The experimental alteration of monazite to allanite, REE-epidote, fluorapatite, and/or fluorapatite-britholite was investigated at 450 to 610 MPa and 450 to 500 {degrees}C. Experiments involved monazite + albite {+/-} K-feldspar + muscovite {+/-} biotite + SiO2 + CaF2 and variety of fluids including H2O, (KCl + H2O), (NaCl + H2O), (CaCl2 + H2O), (Na2Si2O5 + H2O), 1 M HCl, 2 M NaOH, 2 M KOH, 1 M Ca(OH)2, 2 M Ca(OH)2, and (CaCO3 + H2O). The reaction products, or lack thereof, clearly show that the stability relations between monazite, fluorapatite, and allanite or REE-epidote are more dependent on the fluid composition and the ratio of silicate minerals than on the P-T conditions. A high Ca content in the fluid promotes monazite dissolution and the formation of fluorapatite and allanite or REE-epidote. Lowering the Ca content and raising the Na content in the fluid decreases the solubility of monazite but promotes the formation of allanite. Replacing Na with K in the same fluid causes fluorapatite, with a britholite component, to form from the monazite. However, allanite and REE-epidote are not formed. Monazite is stable in the presence of NaCl brines. In KCl brine, monazite shows a very limited reaction to fluorapatite. When the fluid is (Na2Si2O5 + H2O), strong dissolution of monazite occurs resulting in the mobilization of REEs, and actinides to form fluorapatite-britholite and turkestanite. These experimental results are consistent with natural observations of the partial to total replacement of monazite by fluorapatite, REE-epidote, and allanite in fluid-aided reactions involving the anorthite component in plagioclase at mid- to high-grade metamorphic conditions. In contrast, an alkali-bearing environment with excess Na prevents the growth of allanite and eventually promotes the precipitation of secondary monazite. The results from this study provide implications for geochronology and for deducing fluid compositions in metamorphic rocks.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 10
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    The solubility of monazite (LaPO4, PrPO4, NdPO4, and EuPO4) endmembers in aqueous solutions from 100 to 250 °C (2020)
    Elsevier
    Details
    Publication Date: 2020-07-01
    Print ISSN: 0016-7037
    Electronic ISSN: 1872-9533
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Elsevier
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