Science.gov

Sample records for alkali feldspar quartz

  1. Elastic properties of alkali-feldspars

    NASA Astrophysics Data System (ADS)

    Waeselmann, N.; Brown, J.; Angel, R. J.; Ross, N.; Kaminsky, W.

    2013-12-01

    New measurements of single crystal elastic moduli for a suite of the alkali feldspars are reported. In order to interpret Earth's seismic structure, knowledge of the elastic properties of constituent minerals is essential. The elasticity of feldspar minerals, despite being the most abundant phase in Earth's crust (estimated to be more than 60%), were previously poorly characterized. All prior seismic and petrologic studies have utilized 50-year-old results, of questionable quality, based on 1-bar measurements on pseudo-single crystals. Alkali-feldspars present a large experimental challenge associated with their structural complexity. In the K-end member (KAlSi3O8) the symmetry is governed by Al/Si ordering, in the Na-end member (NaAlSi3O8) the symmetry is governed by whether or not there is a displacive collapse of the framework independent of the Al/Si ordering. K-feldspars exhibit monoclinic (C2/m) symmetry (necessitating determination of 13 elastic moduli) if disordered and triclinic (C-1) symmetry (21 elastic moduli) if ordered. Exsolution of Na-rich and K-rich phases is ubiquitous in natural samples, making it difficult to find suitable single phase and untwinned samples for study. The small single domain samples selected for this study were previously characterized by x-ray diffraction and microprobe analysis to ensure adequate sample quality. Surface wave velocities were measured on oriented surfaces of natural and synthetic single crystals using impulsively stimulated light scattering. A surface corrugation with a spacing of about 2 microns was impulsively created by the overlap of 100 ps infrared light pulses. The time evolution of the stimulated standing elastic waves was detected by measuring the intensity of diffraction from the surface corrugation of a variably delayed probe pulse. This method allows accurate (better than 0.2%) determination of velocities on samples smaller than 100 microns. The combination of measured surface wave velocities and

  2. APPLICATIONS OF CATHODOLUMINESCENCE OF QUARTZ AND FELDSPAR TO SEDIMENTARY PETROLOGY.

    USGS Publications Warehouse

    Ruppert, Leslie F.

    1987-01-01

    Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in clastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of clastic rocks when used in conjunction with field and other petrographic analyses.

  3. Cathodoluminescence Characterization of Maskelynite and Alkali Feldspar in Shergottite (Dhofar 019)

    SciTech Connect

    Kayama, M.; Nakazato, T.; Nishido, H.; Ninagawa, K.; Gucsik, A.

    2009-08-17

    Dhofar 019 is classified as an olivine-bearing basaltic shergottite and consists of subhedral grains of pyroxene, olivine, feldspar mostly converted to maskelynite and minor alkali feldspar. The CL spectrum of its maskelynite exhibits an emission band at around 380 nm. Similar UV-blue emission has been observed in the plagioclase experimentally shocked at 30 and 40 GPa, but not in terrestrial plagioclase. This UV-blue emission is a notable characteristic of maskelynite. CL spectrum of alkali feldspar in Dhofar 019 has an emission bands at around 420 nm with no red emission. Terrestrial alkali feldspar actually consists of blue and red emission at 420 and 710 nm assigned to Al-O{sup -}-Al and Fe{sup 3+} centers, respectively. Maskelynite shows weak and broad Raman spectral peaks at around 500 and 580 cm{sup -1}. The Raman spectrum of alkali feldspar has a weak peak at 520 cm{sup -1}, whereas terrestrial counterpart shows the emission bands at 280, 400, 470, 520 and 1120 cm{sup -1}. Shock pressure on this meteorite transformed plagioclase and alkali feldspar into maskelynite and almost glass phase, respectively. It eliminates their luminescence centers, responsible for disappearance of yellow and/or red emission in CL of maskelynite and alkali feldspar. The absence of the red emission band in alkali feldspar can also be due to the lack of Fe{sup 3+} in the feldspar as it was reported for some lunar feldspars.

  4. Anisotropy of magnetic susceptibility in alkali feldspar and plagioclase

    NASA Astrophysics Data System (ADS)

    Biedermann, Andrea R.; Pettke, Thomas; Angel, Ross J.; Hirt, Ann M.

    2016-01-01

    Feldspars are the most abundant rock-forming minerals in the Earth's crust, but their magnetic properties have not been rigorously studied. This work focuses on the intrinsic magnetic anisotropy of 31 feldspar samples with various chemical compositions. Because feldspar is often twinned or shows exsolution textures, measurements were performed on twinned and exsolved samples as well as single crystals. The anisotropy is controlled by the diamagnetic susceptibility and displays a consistent orientation of principal susceptibility axes; the most negative or minimum susceptibility is parallel to [010], and the maximum (least negative) is close to the crystallographic [001] axis. However, the magnetic anisotropy is weak when compared to other rock-forming minerals, 1.53*10-9 m3 kg-1 at maximum. Therefore, lower abundance minerals such as augite, hornblende or biotite often dominate the bulk paramagnetic anisotropy of a rock. Ferromagnetic anisotropy is not significant in most samples. In the few samples that do show ferromagnetic anisotropy, the principal susceptibility directions of the ferromagnetic subfabric do not display a systematic orientation with respect to the feldspar lattice. These results suggest that paleointensity estimates of the geomagnetic field made on single crystals of feldspar will not be affected by a systematic orientation of the ferromagnetic inclusions within the feldspar lattice.

  5. Anisotropy of magnetic susceptibility in alkali feldspar and plagioclase

    NASA Astrophysics Data System (ADS)

    Biedermann, Andrea R.; Pettke, Thomas; Angel, Ross J.; Hirt, Ann M.

    2016-04-01

    Feldspars are the most abundant rock-forming minerals in the Earth's crust, but their magnetic properties have not been rigorously studied. This work focuses on the intrinsic magnetic anisotropy of 31 feldspar samples with various chemical compositions. Because feldspar is often twinned or shows exsolution textures, measurements were performed on twinned and exsolved samples as well as single crystals. The anisotropy is controlled by the diamagnetic susceptibility and displays a consistent orientation of principal susceptibility axes; the most negative or minimum susceptibility is parallel to [010], and the maximum (least negative) is close to the crystallographic [001] axis. However, the magnetic anisotropy is weak when compared to other rock-forming minerals, 1.53 × 10-9 m3 kg-1 at maximum. Therefore, lower abundance minerals, such as augite, hornblende or biotite, often dominate the bulk paramagnetic anisotropy of a rock. Ferromagnetic anisotropy is not significant in most samples. In the few samples that do show ferromagnetic anisotropy, the principal susceptibility directions of the ferromagnetic subfabric do not display a systematic orientation with respect to the feldspar lattice. These results suggest that palaeointensity estimates of the geomagnetic field made on single crystals of feldspar will not be affected by a systematic orientation of the ferromagnetic inclusions within the feldspar lattice.

  6. Sorption Mechanisms of Antibiotic Cephapirin onto Quartz and Feldspar by Raman Spectroscopy

    SciTech Connect

    Peterson, Jonathan; Wang, Wei; Gu, Baohua

    2009-01-01

    Raman spectroscopy was used to investigate the sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO2) and feldspar (KAlSi3O8) at different pH values. Depending on the charge and surface properties of the mineral, different reaction mechanisms including electrostatic attraction, monodentate and bidentate complexation were found to be responsible for CHP sorption. The zwitterion (CHPo) adsorbs to a quartz(+) surface by electrostatic attraction of the carboxylate anion group ( COO-) at a low pH, but adsorbs to a quartz(-) surface through electrostatic attraction of the pyridinium cation and possibly COO- bridge complexes at relatively higher pH conditions. CHP- bonds to a quartz(-) surface by bidentate complexation between one oxygen of COO- and oxygen from the carbonyl (C=O) of the acetoxymethyl group. On a feldspar surface of mixed charge, CHPo forms monodentate complexes between C=O as well as COO- bridging complexes or electrostatically attached to localized edge (hydr)oxy-Al surfaces. CHP- adsorbs to feldspar(-) through monodentate C=O complexation, and similar mechanisms may operate for the sorption of other cephalosporins. This research demonstrates, for the first time, that Raman spectroscopic techniques can be effective for evaluating the sorption processes and mechanisms of cephalosporin antibiotics even at relatively low sorbed concentrations (97-120 μmol/kg).

  7. Thermodynamic assessment of hydrothermal alkali feldspar-mica-aluminosilicate equilibria

    USGS Publications Warehouse

    Sverjensky, D.A.; Hemley, J.J.; d'Angelo, W. M.

    1991-01-01

    The thermodynamic properties of minerals retrieved from consideration of solid-solid and dehydration equilibria with calorimetric reference values, and those of aqueous species derived from studies of electrolytes, are not consistent with experimentally measured high-temperature solubilities in the systems K2O- and Na2O-Al2O3-SiO2-H2O-HCl (e.g., K-fs - Ms - Qtz - K+ - H+). This introduces major inaccuracies into the computation of ionic activity ratios and the acidities of diagenetic, metamorphic, and magmatic hydrothermal fluids buffered by alkali silicate-bearing assemblages. We report a thermodynamic analysis of revised solubility equilibria in these systems that integrates the thermodynamic properties of minerals obtained from phase equilibria studies (Berman, 1988) with the properties of aqueous species calculated from a calibrated equation of state (Shock and Helgeson, 1988). This was achieved in two separate steps. First, new values of the free energies and enthalpies of formation at 25??C and 1 bar for the alkali silicates muscovite and albite were retrieved from the experimental solubility equilibria at 300??C and Psat. Because the latter have stoichiometric reaction coefficients different from those for solid-solid and dehydration equilibria, our procedure preserves exactly the relative thermodynamic properties of the alkali-bearing silicates (Berman, 1988). Only simple arithmetic adjustments of -1,600 and -1,626 (??500) cal/mol to all the K- and Na-bearing silicates, respectively, in Berman (1988) are required. In all cases, the revised values are within ??0.2% of calorimetric values. Similar adjustments were derived for the properties of minerals from Helgeson et al. (1978). Second, new values of the dissociation constant of HCl were retrieved from the solubility equilibria at temperatures and pressures from 300-600??C and 0.5-2.0 kbars using a simple model for aqueous speciation. The results agree well with the conductance-derived dissociation

  8. P- T conditions of crystallization and origin of plagioclase-mantled alkali feldspar megacrysts in the Mesozoic granitoids in the Qinling orogen (China)

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Wang, Tao; Haapala, Ilmari; Mao, Jingwen

    2008-07-01

    The Qinling orogen between the North China and South China cratons was intruded at 211-217 Ma by calc-alkaline quartz monzonitic to monzogranitic plutons characterized by I- to A-type geochemistry and in many places contain plagioclase-mantled alkali feldspar megacrysts (rapakivi texture sensu lato). The felsic rocks contain mafic to intermediate magmatic enclaves suggestive of mingling and mixing of mafic and felsic magmas. The P- T conditions of crystallization have been determined for early mineral assemblages (inner parts of alkali feldspar megacrysts and their plagioclase, quartz, amphibole and biotite inclusions) and late assemblages (matrix minerals) of the rapakivi-textured granitoids. Al contents in amphibole from the early and late mineral assemblages yield pressures of 1.2-3.0 and 0.7-3.0 kbar, respectively, and indicate only minor pressure change between the crystallization of the early and late assemblages. Amphibole-plagioclase thermometry gives temperatures mainly of the order of 900 to 1000 °C for both the early and late assemblages indicating nearly isothermal conditions. Feldspar thermometers yield lower temperatures. Relative abundances of minerals and their chemical compositions indicate that the late mineral assemblages tend to be richer in MgO, Na 2O and CaO than the early assemblages. Rapakivi texture is interpreted in this case mainly as a result of compositional changes related to the hybridization between granitic and more mafic magmas. Small release of pressure during crystallization of the magmas may have contributed to the origin of the mantled alkali feldspar megacrysts.

  9. Experimental alkali feldspar dissolution at 100 degree C by carboxylic acids and their anions

    SciTech Connect

    Stoessell, R.K. ); Pittman, E.D. )

    1990-05-01

    Feldspar dissolution will enhance sandstone porosity if the released aluminum can be transported away in the subsurface waters. Carboxylic acids have been proposed to provide hydrogen ions to promote dissolution and anions to complex aqueous aluminum to keep it in solution. However, the hydrogen ions should react quickly following acid generation in source beds, leaving monocarboxylic anions with lesser amounts of dicarboxylic acids and their anions on feldspar dissolution and the apparent complexing of aluminum in solution. Two-week dissolution experiments of alkali feldspar were run at 100{degree}C and 300 bars in acetic acid, oxalic acid, and sodium salt solutions of chloride, acetate, propionate, oxalate, and malonate. Extrapolation of the results, to reservoir conditions during sandstone diagenesis, implies that concentrations of aluminum-organic complexes are not significant for acetate and propionate and are possibly significant for oxalate and malonate, depending upon fluid compositions. Propionate appeared to inhibit feldspar dissolution and hence might decrease secondary porosity formation. Increases in aluminum concentrations in the presence of oxalic and acetic acid solutions appear to be due to enhanced dissolution kinetics and greater aluminum solubility under low-pH conditions. Such low-pH fluids are generally absent in subsurface reservoirs, making this an unlikely mechanism for enhancing porosity. Furthermore, the observed thermal instability of oxalate and malonate anions explains their general low concentrations in subsurface fluids which limits their aluminum complexing potential in reservoirs during late diagenesis.

  10. Kinetics of feldspar and quartz dissolution at 70-80°C and near-neutral pH: effects of organic acids and NaCl

    NASA Astrophysics Data System (ADS)

    Blake, R. E.; Waltera, L. M.

    1999-07-01

    Effects of the organic acid (OA) anions, oxalate and citrate, on the solubility and dissolution kinetics of feldspars (labradorite, orthoclase, and albite) at 80°C and of quartz at 70°C were investigated at pH 6 in separate batch experiments and in media with different ionic strength (0.02-2.2 M NaCl). Although it has been shown that OAs can increase rates of feldspar dissolution, prior experiments have focused primarily on dilute, highly undersaturated and acidic conditions where feldspar dissolution kinetics are dominated by H + adsorption and exchange reactions. Many natural waters, however, are only weakly acidic and have variable ionic strength and composition which would be expected to influence mineral surface properties and mechanisms of organic ligand-promoted reactions. Oxalate and citrate (2-20 mM) increased the rate of quartz dissolution by up to a factor of 2.5. Quartz solubility, however, was not increased appreciably by these OAs, suggesting that Si-OA complexation is not significant under these conditions. The lack of significant OA-SiO 2 interaction is important to understanding the effects of OAs on the release of both Si and Al from feldspars. In contrast to quartz, both the rates of dissolution and amounts of Si and Al released from the three feldspars studied increased regularly with increasing OA concentration. Feldspar dissolution was congruent at all but the lowest OA concentrations. Total dissolved Al concentrations increased by 1-2 orders of magnitude in the presence of oxalate and citrate, and reached values as high as 43 mg/l (1.6 mM). Si concentrations reached values up to 65 mg/l (2.3 mM) in feldspar-OA experiments. Precipitation of authigenic clays was observed only in experiments without or at very low concentrations of OAs. The high concentrations of dissolved Si attained during dissolution of feldspars in OA solutions, relative to Si concentrations in quartz-OA experiments, is attributed to concomitant release of Si driven by

  11. Lattice strain across Na-K interdiffusion fronts in alkali feldspar: an electron back-scatter diffraction study

    NASA Astrophysics Data System (ADS)

    Schäffer, Anne-Kathrin; Jäpel, Tom; Zaefferer, Stefan; Abart, Rainer; Rhede, Dieter

    2014-11-01

    Cation exchange experiments between gem quality sanidine and KCl melt produced chemical alteration of alkali feldspar starting at the grain surface and propagating inwards by highly anisotropic Na-K interdiffusion on the alkali sublattice. Diffusion fronts developing in b-direction are very sharp, while diffusion fronts within the a- c-plane are comparatively broad. Due to the composition dependence of the lattice parameters of alkali feldspar, the diffusion induced compositional heterogeneity induces coherency stress and elastic strain. Electron back-scatter diffraction combined with the cross-correlation technique was employed to determine the lattice strain distribution across the Na-K interdiffusion fronts in partially exchanged single crystals of alkali feldspar. The strain changes gradually across the broad fronts within the a- c-plane, with a successive extension primarily in a-direction conferring to the composition strain in unstressed alkali feldspar. In contrast, lattice strain characterised by pronounced extension in b-direction is localised at the sharp diffusion fronts parallel to b, followed by a slight expansion in a-direction in the orthoclase-rich rim. This strain pattern does not confer with the composition induced lattice strain in a stress-free alkali feldspar. It may rather be explained by the mechanical coupling of the exchanged surface layer and the mechanically strong substratum. The lattice distortion localised at the sharp diffusion front may have an influence on the diffusion process and appears to produce a self-sharpening feedback, leading to a local reduction of component mobilities.

  12. Crystallization kinetics of alkali feldspars in cooling and decompression-induced crystallization experiments in trachytic melt

    NASA Astrophysics Data System (ADS)

    Arzilli, Fabio; Carroll, Michael R.

    2013-10-01

    Cooling and decompression experiments have been carried out on trachytic melts in order to investigate crystallization kinetics of alkali feldspar, the effect of the degree of undercooling ( ΔT = T liquidus - T experimental) and time on nucleation and crystal growth process. This experimental work gives us new data about crystallization kinetics of trachytic melts, and it that will be useful to better understand the natural system of Campi Flegrei volcanoes. Experiments have been conducted using cold seal pressure vessel apparatus, at pressure between 30 and 200 MPa, temperature between 750 and 855 °C, time between 7,200 and 57,600 s and redox condition close to the NNO +0.8 buffer. These conditions are ideal to reproducing pre- and syn-eruptive conditions of the Campi Flegrei volcanoes, where the "conditions" pertain to the complete range of pressures, temperatures and time at which the experiments were performed. Alkali feldspar is the main phase present in this trachyte, and its abundance can strongly vary with small changes in pressure, temperature and water content in the melt, implying appreciable variations in the textures and in the crystallization kinetics. The obtained results show that crystallization kinetics are strictly related to ΔT, time, final pressure, superheating (- ΔT) and water content in the melt. ΔT is the driving force of the crystallization, and it has a strong influence on nucleation and growth processes. In fact, the growth process dominates crystallization at small ΔT, whereas the nucleation dominates crystallization at large ΔT. Time also is an important variable during crystallization process, because long experiment durations involve more nucleation events of alkali feldspar than short experiment durations. This is an important aspect to understand magma evolution in the magma chamber and in the conduit, which in turn has strong effects on magma rheology.

  13. Characterization of Quartz and Feldspar Deformation in the Mid-crust: Insights from the Cordillera Blanca Shear Zone, Peru

    NASA Astrophysics Data System (ADS)

    Hughes, C. A.; Jessup, M. J.; Shaw, C. A.

    2014-12-01

    Deformation mechanisms within shear zones from various crustal levels must be characterized to develop accurate models of lithospheric rheology. The Cordillera Blanca Shear Zone (CBSZ) in the central Peruvian Andes records changes in temperature, microstructures, and deformation mechanisms that occurred during exhumation through the brittle-ductile-transition during normal-sense slip over the last ~5 m.y. The 100-500-m-thick mylonitic shear zone occupies the footwall of a 200-km-long normal detachment fault, marking the western boundary of the 8 Ma, leucogranodiorite Cordillera Blanca Batholith. Though local variations do occur, including recrystallized quartz veins and local, decimeter- to meter- scale shear zones, the CBSZ follows a general trend of increasing strain towards the detachment. Structurally lowest positions are weakly deformed and transition to protomylonite, mylonite, and ultramylonite at higher positions, truncating at a cataclasite nearest the detachment. We characterize strain using EBSD analyses of quartz lattice preferred orientations and deformation temperatures using quartz and feldspar textures and two-feldspar thermometry of asymmetric strain-induced myrmekite. At the deepest structural positions, feldspar grains record a complex history characterized by bulging recrystallization, myrmekite formation, and brittle fracture, while quartz exhibits dominant grain-boundary migration recrystallization (T> 500 °C) and prism slip. Intermediate samples exhibit more prevalent strain-induced myrmekite, brittle fracture in feldspar, and reaction-associated recrystallization of K-feldspar to mica; quartz records mainly subgrain-rotation recrystallization (400-500 °C) and dominant prism slip with a rhomb component. Shallower positions preserve fewer, smaller, and more rounded feldspar porphyroclasts with no myrmekite, and dominant bulging recrystallization (280-400 °C) in quartz that records prism , rhomb , and some basal slip.

  14. Origin of alkali-feldspar granites: An example from the Poimena Granite, northeastern Tasmania, Australia

    SciTech Connect

    Mackenzie, D.E.; Black, L.P.; Sun, Shensu )

    1988-10-01

    The Lottah Granite is a composite pluton of tin mineralized strongly peraluminous alkali-feldspar granite which intrudes the Poimena Granite, a major component of the mid-Devonian Blue Tier Batholith of northeastern Tasmania. Earlier workers interpreted the Lottah Granite as a metasomatised differentiate of the Poimena Granite. The Poimena Granite is a slightly peraluminous, felsic, I-type biotite granite which contains restite minerals and shows linear trends on Harker plots, both consistent with restite separation. The mineralogy, chemical variation, and isotopic characteristics of the Lottah Granite are consistent with origin as a magma genetically unrelated to the host granite. The Lottah Granite contains sanidine, albite, topaz, zinnwaldite and other minerals consistent with crystallization from a melt. Furthermore, Rb-Sr isotopic dating indicates that the Lottah Granite was emplaced about 10 Ma after the Poimena Granite, and initial Sr and Nd isotope ratios indicate that the Lottah Granite was derived from a higher-{sup 87}Sr/{sup 86}Sr, higher-{epsilon}Nd source composition. Chemical and mineralogical evolution of the Lottah Granite conform to the experimental behavior of Li-F-rich melts, and indicate a possible crystallization temperature range as extreme as 750-430{degree}C. Many other examples of alkali-feldspar granite, and much of the associated mineralization, are probably also of essentially primary magmatic origin rather than of metasomatic or hydrothermal origin as commonly interpreted. They may also be genetically unrelated to granites with which they are associated.

  15. The destruction of quartz, amorphous silica minerals, and feldspars in model experiments and in soils: Possible mechanisms, rates, and diagnostics (the analysis of literature)

    NASA Astrophysics Data System (ADS)

    Sokolova, T. A.

    2013-01-01

    The dissolution of quartz and amorphous SiO2 proceeds via the adsorption of water molecules on the surface of these minerals with the further formation of four silanol groups around the silicon atom and the detachment of the molecules of orthosilicic acid from the surface. The rates of quartz dissolution at pH 7 and 3 constitute 10-15.72 and 10-16.12 mol/m2 s, respectively. They increase by three orders of magnitude upon the rise in pH from 7 to 10; they also increase in the solutions of strong electrolytes and in the presence of the anions of polybasic organic acids. The dissolution of feldspars begins from the release of alkali metals and calcium from the surface of crystal lattices of these minerals into the solution in the course of the cation exchange reaction. This is a fast process, and it does not control the rate of the feldspar dissolution that depends on the concentrations of protonated (in the acid medium) and deprotonated (in the alkaline medium) complexes with participation of the surface Si-O-Si and Al-O-Si groups of the mineral lattices. The rate of dissolution of K-Na feldspars decreases from n × 10-11 to n × 10-12 mol/m2 s upon the rise in pH from 3 to 5; it also increases in the plagioclase series with an increase in the portion of anorthite molecules and in the presence of the anions of polybasic organic acids in the solution. The rate of dissolution of feldspars in the model experiments is by 1-3 orders of magnitude higher than that obtained by different methods for native soils. This may be related to the adequacy of determination of the specific surface and its changes with time in native soils.

  16. 3D distribution and evolution of porosity during albitization and patch perthitization of alkali feldspars

    NASA Astrophysics Data System (ADS)

    Norberg, N.; Neusser, G.; Wirth, R.; Harlov, D. E.

    2010-12-01

    Fluid-mediated replacement of minerals and rocks often results in the formation of an extensive porosity. This reaction-induced porosity is generally assumed to be pervasive enabling the constant progress of the alteration process and fluid infiltration of initially impermeable rocks (e.g. Putnis, 2009 Rev Min Geochem, 70, 87). This hypothesis was tested utilizing state-of-the-art micro- to nano-analytical techniques including FIB in combination with SEM and TEM. For this study two different alkali feldspar replacement reactions common in natural rocks were reproduced experimentally; (i) albitization of K-rich alkali-feldspar (Or85-95) and (ii) patch perthitization of intermediate (exsolved) alkali feldspars (Ab60Or40). 3D analysis of the pore distribution was done by a combination of alternate removal of 100 nm slices using FIB followed by SE imaging of the dissected surface. Series of 100-200 SE images were obtained from 20 × 8 × 20 µm3 sample blocks and translated into a 3-dimensional model using Fiji software package (resolution ~0.03 × 0.03 × 0.1 µm3). Analyses of the experimentally albitized and patch-perthitized alkali feldspar demonstrate that in both cases single-crystalline starting materials are replaced by highly porous, polycrystalline replacement products. In the case of albitization the replacement rim consists of two generations of polycrystalline intergrowths of slightly tilted albite sub-grains visible in TEM. These are a fine-grained, highly porous and a coarse-grained, almost non-porous albite that seems to progressively replace the former. The total reaction-induced porosity clearly exceeds the difference in the molar volume of the reaction of ~ -7.5%. Pores are mostly elongated forming several micron long channels. However, despite the abundance of porosity within the albitized areas, neither 3D analysis nor TEM could detect any significant interconnection between these channels. The same holds true in the case of patch perthitization

  17. Adsorption mechanism of mixed cationic/anionic collectors in feldspar-quartz flotation system.

    PubMed

    Vidyadhar, A; Hanumantha Rao, K

    2007-02-15

    The adsorption mechanism of mixed cationic alkyl diamine and anionic sulfonate/oleate collectors at acidic pH values was investigated on microcline and quartz minerals through Hallimond flotation, electrokinetic and diffuse reflectance FTIR studies. In the presence of anionic collectors, neither of the minerals responded to flotation but the diamine flotation of the minerals was observed to be pH and concentration dependent. The presence of sulfonate enhanced the diamine flotation of the minerals by its co-adsorption. The difference in surface charge between the minerals at pH 2 was found to be the basis for preferential feldspar flotation from quartz in mixed diamine/sulfonate collectors. The infrared spectra revealed no adsorption of sulfonate collector when used alone but displayed its co-adsorption as diamine-sulfonate complex when used with diamine. The presence of sulfonate increased the diamine adsorption due to a decrease in the electrostatic head-head repulsion between the adjacent surface ammonium ions and thereby increasing the lateral tail-tail hydrophobic bonds. The mole ratio of diamine/sulfonate was found to be an important factor in the orientation of alkyl chains and thus the flotation response of minerals. The increase in sulfonate concentration beyond diamine concentration leads to the formation of soluble 1:2 diamine-sulfonate complex or precipitate and the adsorption of these species decreased the flotation since the alkyl chains are in chaotical orientation with a conceivable number of head groups directing towards the solution phase. PMID:17098246

  18. Structure-dependent interactions between alkali feldspars and organic compounds: implications for reactions in geologic carbon sequestration.

    PubMed

    Yang, Yi; Min, Yujia; Jun, Young-Shin

    2013-01-01

    Organic compounds in deep saline aquifers may change supercritical CO(2) (scCO(2))-induced geochemical processes by attacking specific components in a mineral's crystal structure. Here we investigate effects of acetate and oxalate on alkali feldspar-brine interactions in a simulated geologic carbon sequestration (GCS) environment at 100 atm of CO(2) and 90 °C. We show that both organics enhance the net extent of feldspar's dissolution, with oxalate showing a more prominent effect than acetate. Further, we demonstrate that the increased reactivity of Al-O-Si linkages due to the presence of oxalate results in the promotion of both Al and Si release from feldspars. As a consequence, the degree of Al-Si order may affect the effect of oxalate on feldspar dissolution: a promotion of ~500% in terms of cumulative Si concentration was observed after 75 h of dissolution for sanidine (a highly disordered feldspar) owing to oxalate, while the corresponding increase for albite (a highly ordered feldspar) was ~90%. These results provide new insights into the dependence of feldspar dissolution kinetics on the crystallographic properties of the mineral under GCS conditions. PMID:22978468

  19. Quartz and feldspar zoning in the eastern Erzgebirge volcano-plutonic complex (Germany, Czech Republic): evidence of multiple magma mixing

    NASA Astrophysics Data System (ADS)

    Müller, Axel; Breiter, Karel; Seltmann, Reimar; Pécskay, Zoltán

    2005-03-01

    Zoned quartz and feldspar phenocrysts of the Upper Carboniferous eastern Erzgebirge volcano-plutonic complex were studied by cathodoluminescence and minor and trace element profiling. The results verify the suitability of quartz and feldspar phenocrysts as recorders of differentiation trends, magma mixing and recharge events, and suggest that much heterogeneity in plutonic systems may be overlooked on a whole-rock scale. Multiple resorption surfaces and zones, element concentration steps in zoned quartz (Ti) and feldspar phenocrysts (anorthite content, Ba, Sr), and plagioclase-mantled K-feldspars etc. indicate mixing of silicic magma with a more mafic magma for several magmatic phases of the eastern Erzgebirge volcano-plutonic complex. Generally, feldspar appears to be sensitive to the physicochemical changes of the melt, whereas quartz phenocrysts are more stable and can survive a longer period of evolution and final effusion of silicic magmas. The regional distribution of mixing-compatible textures suggests that magma mingling and mixing was a major process in the evolution of these late-Variscan granites and associated volcanic rocks. Quartz phenocrysts from 14 magmatic phases of the eastern Erzgebirge volcano-plutonic complex provide information on the relative timing of different mixing processes, storage and recharge, allowing a model for the distribution of magma reservoirs in space and time. At least two levels of magma storage are envisioned: deep reservoirs between 24 and 17 km (the crystallisation level of quartz phenocrysts) and subvolcanic reservoirs between 13 and 6 km. Deflation of the shallow reservoirs during the extrusion of the Teplice rhyolites triggered the formation of the Altenberg-Teplice caldera above the eastern Erzgebirge volcano-plutonic complex. The deep magma reservoir of the Teplice rhyolite also has a genetic relationship to the younger mineralised A-type granites, as indicated by quartz phenocryst populations. The pre

  20. Fluvial terrace gravels of the "Hochterrasse" (N-Alpine Foreland, Austria): luminescence characteristics of quartz and feldspar

    NASA Astrophysics Data System (ADS)

    Bickel, L.; Lomax, J.; Fiebig, M.

    2012-04-01

    The Northern Alpine Foreland has played a major role in the investigation of glacial and furthermore paleo-climatic events. It was at the beginning of the 20th century, when Albrecht Penck developed the idea of four big alpine glaciations which extended into the alpine foreland. He developed the model of the glacial series in which he correlated terminal moraines with distinguishable terrace bodies. In the case of the fluvial sediments of the Hochterrasse (correlated with marine isotope stage (MIS) 6 in Austrian geological maps) the existence of numerical ages in the Austrian Alpine Foreland is sparse. This study is aimed at shedding light on the luminescence properties of quartz and feldspar derived from Hochterrasse systems in foreland valleys (Traun, Enns and Ybbs valley) so far attributed to the penultimate glaciation. Coarse grain (100-200 µm) K-feldspar and quartz are analyzed by Infrared stimulated luminescence (IRSL), post-Infrared Infrared stimulated luminescence (pIRIR) and optically stimulated luminescence (OSL) methods. One of the issues that arise when dating glaciofluvial quartz from this area is the apparent underestimation of the quartz ages which can vary up to 50% from the calculated IRSL ages. Linearly modulated OSL shows a big contribution of thermally unstable components to the overall equivalent dose (De) which can add to the general underestimation of quartz. Also the measurement of feldspar aliquots is anything but trivial. Luminescence signal intensities are very viable for the samples from the Enns and Traun valley. The samples derived from the Ybbs valley in contrast show very low feldspar signal intensities on most aliquots. Thermal transfer has shown to have negligible impact on the overall paleodose for the feldspar samples (maximum 1% of the paleodose attributed to thermal transfer). In contrast anomalous fading seems to be affecting all feldspar samples. However an assessment of the amount of signal loss in time is difficult to

  1. Ionic conductivity in gem-quality single-crystal alkali feldspar from the Eifel: temperature, orientation and composition dependence

    NASA Astrophysics Data System (ADS)

    El Maanaoui, Hamid; Wilangowski, Fabian; Maheshwari, Aditya; Wiemhöfer, Hans-Dieter; Abart, Rainer; Stolwijk, Nicolaas A.

    2016-05-01

    We measured the ion conductivity of single-crystal alkali feldspar originating from two different locations in the Eifel/Germany, named Volkesfeld and Rockeskyller sanidine and having potassium site fractions C_K of 0.83 and 0.71, respectively. The dc conductivities resulting from electrochemical impedance spectroscopy over the temperature range of 300-900°C show a weak composition dependence but pronounced differences between the b-direction [perp (010)] and c^{*}-direction [perp (001)] of the monoclinic feldspar structure. Conductivity activation energies obtained from the observed linear Arrhenius plots are close to 1.2 eV in all cases, which is closely similar to the activation energies of the ^{22}Na tracer diffusivity in the same crystals. Taking into account literature data on K tracer diffusion and diffusion correlation effects, the present results point to a predominance of the interstitialcy mechanism over the vacancy mechanism in mass and charge transport on the alkali sublattice in potassium-rich alkali feldspar.

  2. Buffering capability of mineral assemblage (feldspar + kaolinite + quartz) and its application to predicting illite occurrence in arkosic sandstones

    SciTech Connect

    Huang, W.L.

    1986-05-01

    Studies of phase relationships using the activity diagrams involving feldspar, illite, kaolinite, and gibbsite (or boehmite) reveal that the common mineral assemblage of feldspar, kaolinite, and quartz found in arkosic sandstone provides a strong driving force to change the fluid chemistry to conditions thermodynamically favoring illite formation. The driving force involves three major diagenetic reactions: the hydrolysis of feldspar with acidic fluid, the reaction of kaolinite with alkaline fluid, and the saturation of the fluid with respect to quartz. The first and second reactions result in, respectively, the increase and decrease of K/sup +//H/sup +/ activity ratio, whereas the third reaction tends to maintain the Si(OH)/sub 4/ activity in the pore fluid. The resultant fluid chemistry of these reactions coincidentally falls in the stability field of illite. This relationship occurs over a wide range of pressure and temperature conditions with low fluid to rock ratio. Experimental results show that an increase in the fluid to rock ratio will decrease the rate that the fluid chemistry approaches the illite stability field. The effectiveness of the buffering capability, therefore, depends on the relative rate of fluid movement and fluid/rock reaction. This study demonstrates that the most likely condition for illite formation is a quartzofeldspathic system involving the presence of kaolinite and low fluid movement. In the absence of these conditions, the opportunity to precipitate illite in the pore space is significantly reduced. The commonly observed illitization of kaolinite or feldspar during burial diagenesis could be caused simply by the reduced influx of fluid (with any compositions: alkaline, neutral, or acidic) due to deep burial of the sandstone.

  3. Time-temperature evolution of microtextures and contained fluids in a plutonic alkali feldspar during heating

    NASA Astrophysics Data System (ADS)

    Parsons, Ian; Fitz Gerald, John D.; Lee, James K. W.; Ivanic, Tim; Golla-Schindler, Ute

    2010-08-01

    Microtextural changes brought about by heating alkali feldspar crystals from the Shap granite, northern England, at atmospheric pressure, have been studied using transmission and scanning electron microscopy. A typical unheated phenocryst from Shap is composed of about 70 vol% of tweed orthoclase with strain-controlled coherent or semicoherent micro- and crypto-perthitic albite lamellae, with maximum lamellar thicknesses <1 μm. Semicoherent lamellae are encircled by nanotunnel loops in two orientations and cut by pull-apart cracks. The average bulk composition of this microtexture is Ab27.6Or71.8An0.6. The remaining 30 vol% is deuterically coarsened, microporous patch and vein perthite composed of incoherent subgrains of oligoclase, albite and irregular microcline. The largest subgrains are ~3 μm in diameter. Heating times in the laboratory were 12 to 6,792 h and T from 300°C into the melting interval at 1,100°C. Most samples were annealed at constant T but two were heated to simulate an 40Ar/39Ar step-heating schedule. Homogenisation of strain-controlled lamellae by Na↔K inter-diffusion was rapid, so that in all run products at >700°C, and after >48 h at 700°C, all such regions were essentially compositionally homogeneous, as indicated by X-ray analyses at fine scale in the transmission electron microscope. Changes in lamellar thickness with time at different T point to an activation energy of ~350 kJmol-1. A lamella which homogenised after 6,800 h at 600°C, therefore, would have required only 0.6 s to do so in the melting interval at 1,100°C. Subgrains in patch perthite homogenised more slowly than coherent lamellae and chemical gradients in patches persisted for >5,000 h at 700°C. Homogenisation T is in agreement with experimentally determined solvi for coherent ordered intergrowths, when a 50-100°C increase in T for An1 is applied. Homogenisation of lamellae appears to proceed in an unexpected manner: two smooth interfaces, microstructurally sharp

  4. Microscopy and Cathodoluminescence Spectroscopy Characterization of Quartz Exhibiting Different Alkali-Silica Reaction Potential.

    PubMed

    Kuchařová, Aneta; Götze, Jens; Šachlová, Šárka; Pertold, Zdeněk; Přikryl, Richard

    2016-02-01

    Different quartz types from several localities in the Czech Republic and Sweden were examined by polarizing microscopy combined with cathodoluminescence (CL) microscopy, spectroscopy, and petrographic image analysis, and tested by use of an accelerated mortar bar test (following ASTM C1260). The highest alkali-silica reaction potential was indicated by very fine-grained chert, containing significant amounts of fine-grained to cryptocrystalline matrix. The chert exhibited a dark red CL emission band at ~640 nm with a low intensity. Fine-grained orthoquartzites, as well as fine-grained metamorphic vein quartz, separated from phyllite exhibited medium expansion values. The orthoquartzites showed various CL of quartz grains, from blue through violet, red, and brown. Two CL spectral bands at ~450 and ~630 nm, with various intensities, were detected. The quartz from phyllite displayed an inhomogeneous dark red CL with two CL spectral bands of low intensities at ~460 and ~640 nm. The massive coarse-grained pegmatite quartz from pegmatite was assessed to be nonreactive and displayed a typical short-lived blue CL (~480 nm). The higher reactivity of the fine-grained hydrothermal quartz may be connected with high concentrations of defect centers, and probably with amorphized micro-regions in the quartz, respectively; indicated by a yellow CL emission (~570 nm). PMID:26790877

  5. Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Lu, Peng; Zheng, Zuoping; Ganor, Jiwchar

    2010-07-01

    This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fourth paper in our series of "Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems". In our third paper, we demonstrated via speciation-solubility modeling that partial equilibrium between secondary minerals and aqueous solutions was not attained in feldspar hydrolysis batch reactors at 90-300 °C and that a strong coupling between dissolution and precipitation reactions follows as a consequence of the slower precipitation of secondary minerals ( Zhu and Lu, 2009). Here, we develop this concept further by using numerical reaction path models to elucidate how the dissolution and precipitation reactions are coupled. Modeling results show that a quasi-steady state was reached. At the quasi-steady state, dissolution reactions proceeded at rates that are orders of magnitude slower than the rates measured at far from equilibrium. The quasi-steady state is determined by the relative rate constants, and strongly influenced by the function of Gibbs free energy of reaction ( ΔG) in the rate laws. To explore the potential effects of fluid flow rates on the coupling of reactions, we extrapolate a batch system ( Ganor et al., 2007) to open systems and simulated one-dimensional reactive mass transport for oligoclase dissolution and kaolinite precipitation in homogeneous porous media. Different steady states were achieved at different locations along the one-dimensional domain. The time-space distribution and saturation indices (SI) at the steady states were a function of flow rates for a given kinetic model. Regardless of the differences in SI, the ratio between oligoclase dissolution rates and kaolinite precipitation rates remained 1.626, as in the batch system case ( Ganor et al., 2007). Therefore, our simulation results demonstrated coupling among dissolution, precipitation, and flow rates

  6. Provenance of sands from the confluence of the Amazon and Madeira rivers based on detrital heavy minerals and luminescence of quartz and feldspar

    NASA Astrophysics Data System (ADS)

    do Nascimento, Daniel R.; Sawakuchi, André O.; Guedes, Carlos C. F.; Giannini, Paulo C. F.; Grohmann, Carlos H.; Ferreira, Manuela P.

    2015-03-01

    Source-to-sink systems are poorly known in tropical rivers. For the Amazonian rivers, the majority of the provenance studies remain focused on the suspended load, implying a poor understanding of the processes governing production and distribution of sands. In this study, we perform heavy mineral and optically stimulated luminescence (OSL) analysis to cover the entire spectrum (heavy and light minerals fraction) of 29 sand samples of the Lower Madeira river region (Amazon and Madeira rivers), of which the main goal was to find provenance indicators specific to these rivers. Despite the tropical humid climate, the sands of the Amazon and Lower Madeira rivers are rich in unstable heavy minerals as augite, hypersthene, green hornblende and andalusite. The Madeira river is highlighted by its higher content of andalusite, with source attributed to the Amazon Craton (medium-to-high grade metamorphic rocks), while the Amazon river, upstream of the Madeira river mouth, has a signature of augite and hypersthene, that suggests an Andean provenance (volcanic rocks). Sands from the Madeira river can be tracked in the Amazon river by the increasing concentration in andalusite. OSL analysis of the light minerals fraction was used as an index of feldspar concentration and sedimentary history of quartz grains. Lower feldspar concentration and quartz grains with longer sedimentary history (higher OSL sensitivity) also point to a major contribution of cratonic sources for the sands in the Madeira river. While the sands from the Lower Madeira would be mainly supplied by cratonic rocks, previous work recognised that suspended sediments (silt and clay) are derived from Andean rocks. Therefore, we interpret a decoupling between the sources of sand and mud (silt and clay) under transport in the Madeira river. Andean sands (rich in augite and hypersthene) would be trapped in the foreland zones of the Beni and Mamoré tributaries. In the Amazon river sands, the low OSL sensitivity of the

  7. New ages for Middle and Later Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz and feldspar grains.

    PubMed

    Gliganic, Luke A; Jacobs, Zenobia; Roberts, Richard G; Domínguez-Rodrigo, Manuel; Mabulla, Audax Z P

    2012-04-01

    The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ~60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for

  8. Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Lu, Peng

    2009-06-01

    In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar-water systems. Speciation and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity-activity diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E. and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona, USA. In Water-Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs, New York. pp. 895-899]. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback between dissolution and

  9. Experimental calibration of cotectic melt compositions coexisting with quartz and feldspar in rhyolitic systems - Application to Snake River Plain rhyolites,Yellowstone hotspot

    NASA Astrophysics Data System (ADS)

    Holtz, F.; Klahn, C.; Bolte, T.; Almeev, R. R.; Christiansen, E. H.; Nash, B. P.

    2013-12-01

    The depth of magma storage prior to eruption is difficult to constrain for rhyolitic systems and remains often unknown because the typical mineral assemblages in rhyolite magmas are not suitable for geobarometry. As an alternative to mineral compositions, the silica content of rhyolitic melts can be used to constrain pressure, provided that the silicate melts have cotectic compositions (melts coexisting with quartz and feldspar). From studies in synthetic haplogranitic systems, it is well known that the silica content of cotectic melts decreases with increasing pressure and that it may be used as barometer. However, the evolution of silica content with pressure is not calibrated for natural rhyolitic systems containing up to 2 wt% CaO and 4 wt% FeO. Crystallization experiments in Fe-, Ca- and Ti-bearing rhyolitic systems have been performed at 200 MPa and a temperature range of 790 to 850°C to calibrate the position of cotectic compositions in natural rhyolitic systems and the results have been projected onto the haplogranitic quartz-albite-orthoclase diagram (Qz-Ab-Or). The starting materials were glasses with various proportions of the Qz, Ab and Or components; all glasses contained 1 wt% FeO, 3.4 wt% An component and 0.2 wt% TiO2. The glasses were pre-hydrated with 3 wt% H2O in an internally heated pressure vessel. The crystallization experiments were conducted in cold seal pressure vessels. The water contents of the pre-hydrated starting glasses were checked by Fourier Transform Infrared Spectroscopy (FTIR) and Karl Fischer titration. The experimental products (glasses and crystals) were analyzed via electron microprobe. Results at 200 MPa show that the cotectic line separating the quartz primary field from the feldspar primary field is shifted towards the Qz apex by 6 wt% when compared with the water-undersaturated haplogranitic system (containing 3 wt% water). The minimum composition is shifted towards the Qz-Or sideline when compared with the haplogranitic

  10. Origin of hydrous alkali feldspar-silica intergrowth in spherulites from intra-plate A2-type rhyolites at the Jabal Shama, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Surour, Adel A.; El-Nisr, Said A.; Bakhsh, Rami A.

    2016-03-01

    Miocene rhyolites (19.2 ± 0.9 Ma) at the Jabal Shama in western Saudi Arabia represent an example of rift-related silicic volcanism that took place during the formation of the Red Sea. They mostly consist of tuffaceous varieties with distinct flow banding, and pea-sized spherulites, obsidian and perlitized rhyolite tuffs. Although they have the geochemical signature of A2-type rhyolites, these silicic rocks are not typically alkaline but alkali-calcic to calc-alkaline. They developed in a within-plate regime and possibly derived from a recycled mafic subducted slab in depleted sub-continental mantle beneath the western Arabian plate. The Jabal Shama rhyolites are younger in age than their Miocene counterparts in Yemen and Ethiopia. The Jabal Shama spherulites consist of hydrous alkali feldspar-silica radial intergrowths with an occasional brown glass nucleus. Carbonate- and glass-free spherulites give up to 4.45 wt% L.O.I. The hydrous nature of these silicates and the absence of magnetite in the spherulites is a strong indication of oxidizing conditions. The spherulites contain hydrous feldspars with up to ∼6 wt% H2O, and they develop by diffusion and devitrification of glass in the rhyolite tuff at ∼800 °C. Owing to higher undercooling due to supersaturation, the radial hydrous phases within spherulites might grow faster and led to coagulation. The polygonal contacts between spherulites and the ∼120° dihedral angle suggest solid-state modification and recrystallization as the process of devitrification proceeds as low as ∼300 °C. The sum of FeO + MgO is positively correlated with total alkalies along with magnetite oxidation in the matrix to Fe-oxyhydroxides, and to the incorporation of OH- into silicates within the spehrulites themselves. Structural H2O in glass of the Jabal Shama perlite (obsidian) is considerable (∼9-12 wt%) with 3.72-5.6 wt% L.O.I. of the whole-rock. The presence of deleterious silica impurities would lower the ore grade due to

  11. Dissolution of Quartz, Albite and K-feldspar Into H2O-Saturated Haplogranitic Melt at 800oC and 200 MPa: Diffusive Transport Properties of Granitic Melts at Crustal Anatectic Temperatures

    NASA Astrophysics Data System (ADS)

    Acosta, A.; London, D.; Dewers, T.; Morgan, G.

    2002-12-01

    With the aim of investigating the diffusive transport properties of granitic melts at crustal anatectic conditions and obtaining some constraints on speciation and coordination in the melt, we conducted albite, K-feldspar and quartz dissolution experiments in H2O-saturated metaluminous haplogranitic glass (nominal composition of the 200 MPa H2O-saturated haplogranite eutectic of Tuttle and Bowen, 1958) at 800oC and 200 MPa. Mineral and glass cylinders were juxtaposed against flat polished surfaces inside platinum or gold capsules, then run for durations in the range 120-960 h. Based on the time dependence of interface retreat dissolution is interface reaction-controlled up to 700 h, and becomes diffusion-controlled afterwards. Upon dissolution of albite, Al and Na entering the melt decouple and Na diffuses away from the interface to maintain a constant Al/Na molar ratio throughout the entire melt column. Potassium from the bulk melt diffuses uphill towards the albite-melt interface to maintain a constant Aluminum Saturation Index (ASI=molar Al2O3/Na2O+K2O) of 1.00 throughout the entire melt column. Dissolution of K-feldspar results in migration of K away from the interface and uphill diffusion of Na from the bulk melt towards the interface, again maintaining constant Al/Na and ASI ratios in the bulk melt. Dissolution of quartz produces enrichment in SiO2 versus dilution of the rest of components in the interface melt. These results indicate that in the five-component H2O-saturated metaluminous haplogranite system, uncoupled diffusion takes place along the following four directions in composition space: SiO2; Na2O; K2O; and a combination of Al2O3 and alkalis such that the Al/Na molar ratio is equal to that in the bulk melt, and the Al2O3/Na2O+K2O molar ratio is equal to the equilibrium ASI of the melt. These observations are in accord with results obtained from corundum and andalusite dissolution experiments in the same system and P-T-X conditions (Acosta-Vigil et

  12. Peralkaline fluid composition in equilibrium with K-feldspar, muscovite and quartz at 10 kbar and 700°C: Al transport in crustal fluids

    NASA Astrophysics Data System (ADS)

    Wohlers, A.; Manning, C. E.

    2012-04-01

    Aluminum is commonly regarded as one of the least soluble elements during metamorphic and metasomatic processes. However, abundant field evidence suggests that aluminum transport can occur in natural hydrothermal processes. For example, late formed aluminumsilicate-bearing and muscovite-bearing veins are widely observed in high-grade metamorphic rocks, and provide a persuasive argument for considerable mobility of aluminum in aqueous fluid. The present study explores the fluid composition coexisting with K-feldspar (K-fsp), muscovite (ms), corundum (co) and quartz (qz) at deep crustal metamorphic conditions, using a piston cylinder device at 10 kbar and 700°C. Starting materials of natural microcline, quartz, synthetic corundum, reagent Al2O3 and KSi3O6.5 glass was used. Ms and K-fsp dissolve incongruently to co + fluid and ms + fluid, respectively. Fluid composition in equilibrium with co + ms and ms + K-fsp were located in experiments with and without qz. In quartz-absent experiments fluid composition with co+ms (I1) is mAl = 0.11, mK = 0.15, mSi = 0.44, and with K-fsp + ms (I2) mAl = 0.18, mK = 0.28 and mSi = 0.81, where mi is molality of the subscripted element. Fluid compositions with qz are: mAl = 0.08, mK = 0.11 and mSi = 1.18 (co + ms + qtz; II1) and mAl = 0.18, mK = 0.29 and mSi = 1.58 for (K-fsp + ms +qtz; II2). Measured fluid compositions are peralkaline (K/Al < 1.4). Bulk solubility of Al in pure H2O at this P and T is reported to be ~0.3 wt% [1], and increase to ~1.9 wt % Al in the presence of SiO2 [2]. This study shows that Al solubility is further enhanced by the presence of K and Si, increasing from ~4.07 wt% for (I1) to ~ 7.14 wt% at (I2). Presence of quartz enhances the bulk solubility from ~ 7.63 wt% (II1) to ~ 12.05 wt % at (II2). Results indicate that substantial aluminum transfer may occur at deep-crust metamorphic conditions in aqueous solutions equilibrated with common crustal bulk compositions such as metapelites and granites. Such high Al

  13. Preparation and characterization of new dental porcelains, using K-feldspar and quartz raw materials. Effect of B2O3 additions on sintering and mechanical properties.

    PubMed

    Harabi, Abdelhamid; Guerfa, Fatiha; Harabi, Esma; Benhassine, Mohamed-Tayeb; Foughali, Lazhar; Zaiou, Soumia

    2016-08-01

    The aim of this work was to determine the effect of temperature and boric oxide (B2O3) addition on sintering and mechanical properties of a newly developed dental porcelain (DP) prepared from local Algerian raw materials. Based on a preliminary work, the new selected composition was 75wt.% feldspar, 20wt.% quartz and 5wt.% kaolin. It was prepared by sintering the mixture at different temperatures (1100-1250°C). The optimum sintering conditions gave a relatively higher density (2.47g/cm(3)) and excellent mechanical properties. The three point flexural strength (3PFS) and Martens micro-hardness of dental porcelains were 149MPa and 2600MPa, respectively. This obtained 3PFS value is more than four times greater than that of hydroxyapatite (HA) value (about 37MPa) sintered under the same conditions. However, the sintering temperature was lowered by about 25 and 50°C for 3 and 5wt.% B2O3 additions, respectively. But, it did not improve furthermore the samples density and their mechanical properties. It has also been found that B2O3 additions provoke a glass matrix composition variation which delays the leucite formation during sintering. PMID:27157725

  14. Complex impedance spectroscopy of alkali impurities in as-grown, irradiated and annealed quartz

    SciTech Connect

    Devautour-Vinot, S.; Cambon, O.; Prud'homme, N.; Giuntini, J. C.; Boy, J.-J.; Cibiel, G.

    2007-11-15

    This work compares the dielectric relaxation properties of different crystalline quartz materials, according to their source (natural or synthetics). It is shown that these relaxation properties are due to a hopping process of alkaline (Li{sup +}, Na{sup +}, and K{sup +}) impurities located near [Al-O{sub 4}]{sup 5-} tetrahedra. A detailed analysis, in terms of the distribution function of the dielectric loss peak, allowed us to perfectly distinguish the different types of as-grown quartz. We show that (i) the natural quartz has less stable M{sup +} charge carriers than the synthetic materials and that (ii) the homogeneity of the M{sup +} trapping sites, created by the [Al-O{sub 4}]{sup 5-} tetrahedra, strongly depends on the crystal growth conditions. These features were then studied using quartz samples with different treatment conditions: as-grown, irradiated, or annealed at high temperature. We propose that the irradiation greatly facilitates the M{sup +} relaxation, by creating additional low energy M{sup +} hosting sites, whose number depends on the source of the quartz crystals. We also show that for 100 krad irradiation, the saturation state of the defects is already reached for all the materials under consideration. Finally, we propose that the irradiation followed by annealing at 450 deg. C improves the M{sup +} stability and homogeneity in quartz materials, compared with the as-grown materials, this trend being much more relevant for the natural than for the synthetic quartz.

  15. Elastic properties of alpha quartz and the alkali halides based on an interatomic force model.

    NASA Technical Reports Server (NTRS)

    Weidner, D. J.; Simmons, G.

    1972-01-01

    A two-body central-force atomic model can be used to describe accurately the elastic properties of alpha quartz if the nontetrahedral O:O forces are included. The strength of the Si:O interaction has little effect on the bulk modulus. The technique is sufficiently general to allow calculations of the elastic properties of a specified structure under arbitrary pressure from a complete description of the interatomic forces. The elastic constants for the NaCl structure and the CsCl structure are examined. Our model includes two-body, central, anion-anion, anion-cation, and electrostatic interactions.

  16. Feldspar dissolution rates in the Topopah Spring Tuff, Yucca Mountain, Nevada

    USGS Publications Warehouse

    Bryan, C.R.; Helean, K.B.; Marshall, B.D.; Brady, P.V.

    2009-01-01

    Two different field-based methods are used here to calculate feldspar dissolution rates in the Topopah Spring Tuff, the host rock for the proposed nuclear waste repository at Yucca Mountain, Nevada. The center of the tuff is a high silica rhyolite, consisting largely of alkali feldspar (???60 wt%) and quartz polymorphs (???35 wt%) that formed by devitrification of rhyolitic glass as the tuff cooled. First, the abundance of secondary aluminosilicates is used to estimate the cumulative amount of feldspar dissolution over the history of the tuff, and an ambient dissolution rate is calculated by using the estimated thermal history. Second, the feldspar dissolution rate is calculated by using measured Sr isotope compositions for the pore water and rock. Pore waters display systematic changes in Sr isotopic composition with depth that are caused by feldspar dissolution. The range in dissolution rates determined from secondary mineral abundances varies from 10-16 to 10-17 mol s-1 kg tuff-1 with the largest uncertainty being the effect of the early thermal history of the tuff. Dissolution rates based on pore water Sr isotopic data were calculated by treating percolation flux parametrically, and vary from 10-15 to 10-16 mol s-1 kg tuff-1 for percolation fluxes of 15 mm a-1 and 1 mm a-1, respectively. Reconciling the rates from the two methods requires that percolation fluxes at the sampled locations be a few mm a-1 or less. The calculated feldspar dissolution rates are low relative to other measured field-based feldspar dissolution rates, possibly due to the age (12.8 Ma) of the unsaturated system at Yucca Mountain; because oxidizing and organic-poor conditions limit biological activity; and/or because elevated silica concentrations in the pore waters (???50 mg L-1) may inhibit feldspar dissolution. ?? 2009 Elsevier Ltd. All rights reserved.

  17. Mineralogy of silicate inclusions of the Colomera IIE iron and crystallization of Cr-diopside and alkali feldspar from a partial melt

    NASA Astrophysics Data System (ADS)

    Takeda, Hiroshi; Hsu, Weibiao; Huss, Gary R.

    2003-06-01

    We studied the mineralogy, mineral chemistry, and compositions of 48 interior silicate inclusions and a large K-rich surface inclusion from the Colomera IIE iron meteorite. Common minerals in the interior silicate inclusions are Cr diopside and Na plagioclase (albite). They are often enclosed by or coexist with albitic glasses with excess silica and minor Fe-Mg components. This mineral assemblage is similar to the "andesitic" material found in the Caddo County IAB iron meteorite for which a partial melt origin has been proposed. The fairly uniform compositions of Cr diopside (Ca 44Mg 46Fe 10) and Na plagioclase (Or 2.5Ab 90.0An 7.5 to Or 3.5Ab 96.1An 0.4) in Colomera interior inclusions and the angular boundaries between minerals and metal suggest that diopside and plagioclase partially crystallized under near-equilibrium conditions from a common melt before emplacement into molten metal. The melt-crystal assemblage has been called "crystal mush." The bulk compositions of the individual composite inclusions form an array between the most diopside-rich inclusion and plagioclase. This is consistent only with a simple mechanical mixing relationship, not a magmatic evolution series. We propose a model in which partly molten metal and crystal mush were mixed together by impact on the IIE parent body. Other models involving impact melting of the chondritic source material followed by growth of diopside and plagioclase do not easily explain near equilibrium growth of diopside and Na plagioclase, followed by rapid cooling. In the K-rich surface inclusion, K feldspar, orthopyroxene, and olivine were found together with diopside for the first time. K feldspar (sanidine, Or 92.7Ab 7.2An 0.1 to Or 87.3Ab 11.0An 1.7) occurs in an irregular veinlike region in contact with large orthopyroxene crystals of nearly uniform composition (Ca 1.3Mg 80.5Fe 17.8 to Ca 3.1Mg 78.1Fe 18.9) and intruding into a relict olivine with deformed-oval shape. Silica and subrounded Cr diopside are

  18. Sintering behaviour of feldspar and influence of electric charge effects

    NASA Astrophysics Data System (ADS)

    Gallala, W.; Gaied, M. E.

    2011-04-01

    The characterization of feldspar for electric porcelain and the behaviour of these materials after heating at 1230°C were studied. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) were used to identify the present phases and the densification level. Feldspar sand was treated by flotation. The floated feldspar is constituted by microcline, quartz, and minor amounts of albite. The microstructure of sintered feldspar at 1230°C is essentially vitreous with open microporosities. The dielectrical properties of composites were characterized by using the induced courant method (ICM), which indicates that the charge trapping capacity depends on the mineralogical and chemical composition of feldspar.

  19. Natural radioactivity and rare earth elements in feldspar samples, Central Eastern desert, Egypt.

    PubMed

    Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman

    2011-05-01

    The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km(2) of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the margins. The feldspars vary in color from rose to milky and in composition from K-feldspar to Na-feldspar, sometimes interactions of both types are encountered. Thirteen feldspar samples were collected from different locations in the Abu Dob area for measuring the natural radioactivity of (238)U, (232)Th and (40)K using an HPGe detector. The variation in concentration of radionuclides for the area under investigation can be classified into regions of high, medium and low natural radioactivity. The average concentration in BqKg(-1) has been observed to be from 9.5 to 183675.7BqKg(-1) for (238)U, between 6.1 and 94,314.2BqKg(-1) for (232)Th and from 0 to 7894.6BqKg(-1) for (40)K. Radium equivalent activities (Ra(eq)), dose rate (D(R)) and external hazard (H(ex)) have also been determined. In the present work, the concentration of rare earth elements are measured for two feldspar samples using two techniques, Environmental Scanning Electron microscope XIL 30 ESEM, Philips, and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The existence of rare earth elements in this area are very high and can be used in different important industries. PMID:21324705

  20. Particle size and X-ray analysis of Feldspar, Calvert, Ball, and Jordan soils

    NASA Technical Reports Server (NTRS)

    Chapman, R. S.

    1977-01-01

    Pipette analysis and X-ray diffraction techniques were employed to characterize the particle size distribution and clay mineral content of the feldspar, calvert, ball, and jordan soils. In general, the ball, calvert, and jordan soils were primarily clay size particles composed of kaolinite and illite whereas the feldspar soil was primarily silt-size particles composed of quartz and feldspar minerals.

  1. A detailed study of ice nucleation by feldspar minerals

    NASA Astrophysics Data System (ADS)

    Whale, T. F.; Murray, B. J.; Wilson, T. W.; Carpenter, M. A.; Harrison, A.; Holden, M. A.; Vergara Temprado, J.; Morris, J.; O'Sullivan, D.

    2015-12-01

    Immersion mode heterogeneous ice nucleation plays a crucial role in controlling the composition of mixed phase clouds, which contain both supercooled liquid water and ice particles. The amount of ice in mixed phase clouds can affect cloud particle size, lifetime and extent and so affects radiative properties and precipitation. Feldspar minerals are probably the most important minerals for ice nucleation in mixed phase clouds because they nucleate ice more efficiently than other components of atmospheric mineral dust (Atkinson et al. 2013). The feldspar class of minerals is complex, containing numerous chemical compositions, several crystal polymorphs and wide variations in microscopic structure. Here we present the results of a study into ice nucleation by a wide range of different feldspars. We found that, in general, alkali feldspars nucleate ice more efficiently than plagioclase feldspars. However, we also found that particular alkali feldspars nucleate ice relatively inefficiently, suggesting that chemical composition is not the only important factor that dictates the ice nucleation efficiency of feldspar minerals. Ice nucleation by feldspar is described well by the singular model and is probably site specific in nature. The alkali feldspars that do not nucleate ice efficiently possess relatively homogenous structure on the micrometre scale suggesting that the important sites for nucleation are related to surface topography. Ice nucleation active site densities for the majority of tested alkali feldspars are similar to those found by Atkinson et al (2013), meaning that the validity of global aerosol modelling conducted in that study is not affected. Additionally, we have found that ice nucleation by feldspars is strongly influenced, both positively and negatively, by the solute content of droplets. Most other nucleants we have tested are unaffected by solutes. This provides insight into the mechanism of ice nucleation by feldspars and could be of importance

  2. Residence times of alkali feldspar phenocrysts from magma feeding the Agnano-Monte Spina Eruption (4.7 ka), Campi Flegrei caldera (Napoli, southern Italy) based on Ba-zonation modelling

    NASA Astrophysics Data System (ADS)

    Iovine, Raffaella Silvia; Wörner, Gerhard; Carmine Mazzeo, Fabio; Arienzo, Ilenia; Fedele, Lorenzo; Civetta, Lucia; D'Antonio, Massimo; Orsi, Giovanni

    2016-04-01

    Timescales governing the development of crustal magma reservoirs are a key for understanding magmatic processes such as ascent, storage and mixing event. An estimate of these timescales can provide important constraints for volcanic hazard assessment of active volcanoes. We studied the Agnano-Monte Spina eruption (A-MS; 4.7 ka; VEI = 4; 0.85 km3 D.R.E. of magma erupted) of the Campi Flegrei caldera, one of the most dangerous volcanic areas on Earth. The A-MS eruption has been fed by magmas varying from more to less evolved trachyte whose variable 87Sr/86Sr and trace elements features suggest magma mixing between two end-members. Ba zonation profiles of alkali feldspar phenocrysts have been determined through combined energy-dispersive and wavelength-dispersive electron microprobe analyses (EDS-WDS-EMPA). We focused on distinct compositional breaks near the rim of the crystals that likely represent the last mixing event prior to eruption. We always chose the steepest gradients close to the crystal rims, taking into account that any effects related to cutting angles or crystal orientation should give longer apparent diffusion times. Two different approaches were undertaken: (1) a quantitative Ba compositional profiles were measured by point analyses along a short transect crossing growth discontinuities and (2) grey-scale profiles were taken parallel to the acquired point profiles. Assuming that Ba dominates the backscattered electron intensities in sanidines, greyscale gradients can be used as a diffusive tracer. BSE images were processed using the ImageJ® software, in order to extract a numerical greyscale profile. In both cases, each profile was interpolated through a non-linear Boltzmann fit curve with the Mathematica® software. A few traverses done at angles smaller than 90° to the compositional boundary interface were corrected by multiplying the distance values by the sinus of the traverse angle relative to the vertical on the interface. Our preliminary

  3. Principles of Thermal Expansion in Feldspars

    NASA Astrophysics Data System (ADS)

    Hovis, Guy; Medford, Aaron; Conlon, Maricate; Tether, Allison; Romanoski, Anthony

    2010-05-01

    Following the recent thermal expansion work of Hovis et al. (1) on AlSi3 feldspars, we have investigated the thermal expansion of plagioclase, Ba-K, and Ca-K feldspar crystalline solutions. X-ray powder diffraction data were collected between room temperature and 925 °C on six natural plagioclase specimens ranging in composition from anorthite to oligoclase, the K-exchanged equivalents of these plagioclase specimens, and five synthetic Ba-K feldspars with compositions ranging from 25 to 99 mol % BaAl2Si2O8. The resulting thermal expansion coefficients (α) for volume have been combined with earlier results for end-member Na- and K-feldspars (2,3). Unlike AlSi3 feldspars, Al2Si2 feldspars, including anorthite and celsian from the present study plus Sr- and Pb-feldspar from other workers (4,5), show essentially constant and very limited thermal expansion, regardless of divalent cation size. In the context of structures where the Lowenstein rule (6) requires Al and Si to alternate among tetrahedra, the proximity of bridging Al-O-Si oxygen ions to divalent neighbors (ranging from 0 to 2) produces short Ca-O (or Ba-O) bonds (7,8) that apparently are the result of local charge-balance requirements (9). Gibbs et al. (10) suggest that short bonds such as these have a partially covalent character. This in turn stiffens the structure. Thus, for feldspar series with coupled substitution the change away from a purely divalent M-site occupant gives the substituting (less strongly bonded) monovalent cations increasingly greater influence on thermal expansion. Overall, then, thermal expansion in the feldspar system is well represented on a plot of α against room-temperature volume, where one sees a quadrilateral bounded by data for (A) AlSi3 feldspars whose expansion behavior is controlled largely by the size of the monovalent alkali-site occupant, (B) Al2Si2 feldspars whose expansion is uniformly limited by partially-covalent bonds between divalent M-site occupants and

  4. Oriented feldspar-feldspathoid intergrowths in rocks of the Khibiny massif: genetic implications

    NASA Astrophysics Data System (ADS)

    Ageeva, Olga A.; Abart, Rainer; Habler, Gerlinde; Ye. Borutzky, Boris; Trubkin, Nikolay V.

    2012-09-01

    Poikilitic megacrysts of alkali feldspar with abundant inclusions of feldspar-nepheline and feldspar-kalsilite micrographic or lamellar intergrowths are characteristic for the rischorrites of the Khibiny massif. Strict crystallographic orientation relations were identified among the intergrowth phases based on optical investigation using a 4-axes universal stage and crystal orientation imaging using electron back scatter diffraction. The most frequently observed orientation relation is the parallel orientation of the kalsilite and nepheline [001] directions with the [010] direction of the alkali feldspar host and concomitant coincidence of the feldspathoid [100] directions with the [100]-, [101]- and [001] directions of the alkali feldspar. The presence of relic nepheline within intergrowth domains and the successive replacement of precursor nepheline by alkali feldspar and associated formation of feldspar-feldspathoid intergrowth suggest development of the rischorrites from feldspar urtites, in which nepheline is the dominant felsic phase. The metasomatic nature of the transformation of urtites to rischorrites is identified from massive introduction of potassium and silica and removal of sodium. Metasomatism occurred at high temperature; the gigantic apatite deposits of the Khibiny massif seem to be related to this metasomatic event.

  5. Identification of Ice Nucleation Active Sites on Feldspar Dust Particles

    PubMed Central

    2015-01-01

    Mineral dusts originating from Earth’s crust are known to be important atmospheric ice nuclei. In agreement with earlier studies, feldspar was found as the most active of the tested natural mineral dusts. Here we investigated in closer detail the reasons for its activity and the difference in the activity of the different feldspars. Conclusions are drawn from scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, and oil-immersion freezing experiments. K-feldspar showed by far the highest ice nucleation activity. Finally, we give a potential explanation of this effect, finding alkali-metal ions having different hydration shells and thus an influence on the ice nucleation activity of feldspar surfaces. PMID:25584435

  6. Can cathodoluminescence of feldspar be used as provenance indicator?

    NASA Astrophysics Data System (ADS)

    Scholonek, Christiane; Augustsson, Carita

    2016-05-01

    We have studied feldspar from crystalline rocks for its textural and spectral cathodoluminescence (CL) characteristics with the aim to reveal their provenance potential. We analyzed ca. 60 rock samples of plutonic, volcanic, metamorphic, and pegmatitic origin from different continents and of 16 Ma to 2 Ga age for their feldspar CL textures and ca. 1200 feldspar crystals from these rocks for their CL color spectra. Among the analyzed rocks, igneous feldspar is most commonly zoned, whereby oscillatory zoning can be confirmed to be typical for volcanic plagioclase. The volcanic plagioclase also less commonly contains twin lamellae that are visible in CL light than crystals from other rock types. Alkali feldspar, particularly from igneous and pegmatitic rocks, was noted to be most affected by alteration features, visible as dark spots, lines and irregular areas. The size of all textural features of up to ca. 150 μm, in combination with possible alteration in both the source area and the sedimentary system, makes the CL textures of feldspar possible to use for qualitative provenance research only. We observed alkali feldspar mostly to luminesce in a bluish color and sometimes in red, and plagioclase in green to yellow. The corresponding CL spectra are dominated by three apparent intensity peaks at 440-520 nm (mainly blue), 540-620 nm (mainly green) and 680-740 nm (red to infrared). A dominance of the peak in the green wavelength interval over the blue one for plagioclase makes CL particularly useful for the differentiation of plagioclase from alkali feldspar. An apparent peak position in red to infrared at < 710 nm for plagioclase mainly is present in mafic rocks. Present-day coastal sand from Peru containing feldspar with the red to infrared peak position mainly exceeding 725 nm for northern Peruvian sand and a larger variety for sand from southern Peru illustrates a discriminative effect of different source areas. We conclude that the provenance application

  7. Elasticity of plagioclase feldspars

    NASA Astrophysics Data System (ADS)

    Brown, J. Michael; Angel, Ross J.; Ross, Nancy L.

    2016-02-01

    Elastic properties are reported for eight plagioclase feldspars that span compositions from albite (NaSi3AlO8) to anorthite (CaSi2Al2O8). Surface acoustic wave velocities measured using Impulsive Stimulated Light Scattering and compliance sums from high-pressure X-ray compression studies accurately determine all 21 components of the elasticity tensor for these triclinic minerals. The overall pattern of elasticity and the changes in individual elastic components with composition can be rationalized on the basis of the evolution of crystal structures and chemistry across this solid-solution join. All plagioclase feldspars have high elastic anisotropy; a* (the direction perpendicular to the b and c axes) is the softest direction by a factor of 3 in albite. From albite to anorthite the stiffness of this direction undergoes the greatest change, increasing twofold. Small discontinuities in the elastic components, inferred to occur between the three plagioclase phases with distinct symmetry (C1>¯, I1>¯, and P1>¯), appear consistent with the nature of the underlying conformation of the framework-linked tetrahedra and the associated structural changes. Measured body wave velocities of plagioclase-rich rocks, reported over the last five decades, are consistent with calculated Hill-averaged velocities using the current moduli. This confirms long-standing speculation that previously reported elastic moduli for plagioclase feldspars are systematically in error. The current results provide greater assurance that the seismic structure of the middle and lower crusts can be accurately estimated on the basis of specified mineral modes, chemistry, and fabric.

  8. Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization

    USGS Publications Warehouse

    Zhu, Chen; Veblen, D.R.; Blum, A.E.; Chipera, S.J.

    2006-01-01

    Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3-5 ??m thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ???105 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the

  9. Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Veblen, David R.; Blum, Alex E.; Chipera, Stephen J.

    2006-09-01

    Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3-5 μm thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ˜10 5 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the

  10. Progressive deformation of feldspar recording low-barometry impact processes, Tenoumer impact structure, Mauritania

    NASA Astrophysics Data System (ADS)

    Jaret, Steven J.; Kah, Linda C.; Harris, R. Scott

    2014-06-01

    The Tenoumer impact structure is a small, well-preserved crater within Archean to Paleoproterozoic amphibolite, gneiss, and granite of the Reguibat Shield, north-central Mauritania. The structure is surrounded by a thin ejecta blanket of crystalline blocks (granitic gneiss, granite, and amphibolite) and impact-melt rocks. Evidence of shock metamorphism of quartz, most notably planar deformation features (PDFs), occurs exclusively in granitic clasts entrained within small bodies of polymict, glass-rich breccia. Impact-related deformation features in oligoclase and microcline grains, on the other hand, occur both within clasts in melt-breccia deposits, where they co-occur with quartz PDFs, and also within melt-free crystalline ejecta, in the absence of co-occurring quartz PDFs. Feldspar deformation features include multiple orientations of PDFs, enhanced optical relief of grain components, selective disordering of alternate twins, inclined lamellae within alternate twins, and combinations of these individual textures. The distribution of shock features in quartz and feldspar suggests that deformation textures within feldspar can record a wide range of average pressures, starting below that required for shock deformation of quartz. We suggest that experimental analysis of feldspar behavior, combined with detailed mapping of shock metamorphism of feldspar in natural systems, may provide critical data to constrain energy dissipation within impact regimes that experienced low average shock pressures.

  11. Modeling H, Na, and K diffusion in plagioclase feldspar by relating point defect parameters to bulk properties

    NASA Astrophysics Data System (ADS)

    Zhang, Baohua; Shan, Shuangming; Wu, Xiaoping

    2016-02-01

    Hydrogen and alkali ion diffusion in plagioclase feldspars is important to study the evolution of the crust and the kinetics of exsolution and ion-exchange reactions in feldspars. Using the available PVT equation of state of feldspars, we show that the diffusivities of H and alkali in plagioclase feldspars as a function of temperature can be successfully reproduced in terms of the bulk elastic and expansivity data through a thermodynamic model that interconnects point defect parameters with bulk properties. Our calculated diffusion coefficients of H, Na, and K well agree with experimental ones when uncertainties are considered. Additional point defect parameters such as activation enthalpy, activation entropy, and activation volume are also predicted. Furthermore, the electrical conductivity of feldspars inferred from our predicted diffusivities of H, Na, and K through the Nernst-Einstein equation is compared with previous experimental data.

  12. Feldspar diagenesis in the Frio Formation, Brazoria County, Texas Gulf Coast

    SciTech Connect

    Land, L.S.; Milliken, K.L.

    1981-07-01

    Tremendous quantities of detrital feldspar have been dissolved or albitized below about 14000 ft (4267 m) in the Frio Formation (Oligocene), Chocolate Bayou Field, Brazoria County, Texas. Some sandstones no longer contain any unmodified detrital feldspar grains. Material transfer involved in these reactions is immense, affecting at least 15% of the rock volume. Thus, albitization has important implications for several other diagenetic processes that involve feldspars or their components. These processes include formation of secondary porosity, precipitation of quartz and carbonate cements, and the evolution of Na-Ca-Cl formation water.

  13. Alkali-granitoids as fragments within the ordinary chondrite Adzhi-Bogdo: Evidence for highly fractionated, alkali-granitic liquids on asteroids

    NASA Technical Reports Server (NTRS)

    Bischoff, A.

    1993-01-01

    Adzhi-Bogdo is an ordinary chondrite regolith breccia (LL3-6) that fell October 30, 1949 in Gobi Altay, Mongolia. The rock consists of submm- to cm-sized fragments embedded in a fine-grained elastic matrix. The breccia contains various types of clasts, some of which must be of foreign heritage. Based on chemical compositions of olivine some components have to be classified as L-type. Components of the breccia include chondrules, impact melts (some are K-rich, similar to those found in other LL-chondrites, highly recrystalized rock fragments ('granulites'), pyroxene-rich fragments with achondritic textures, and alkali-granitoidal fragments that mainly consist of K-feldspar and quartz or tridymite. Probably, this is the first report on granitoids from asteroids. It can be ruled out that these fragments represent huge rock assemblages of the parent body like granites do on Earth. Therefore, to avoid misunderstandings, these rocks will be designated as granitoids. In one thin section four granitoids were observed. The main phases within these clasts are K-feldspar and SiO2-phases. Minor phases include albite, Cl-apatite, whitlockite, ilmenite, zircon, Ca-poor pyroxene, and an unidentified Na,Ti-bearing silicate. Based on chemical composition and on optical properties quartz appears to be the SiO2-phase in two fragments, whereas tridymite seems to occur in the other two. The calculated formula of the unknown Na,Ti-rich silicate is very close to (Na,Ca)2.7(Fe,Mg)6(Ti)1.3(Si)7(O)24. Quartz and K-feldspar can reach sizes of up to 700 microns. Thus, the fragments can be described as coarse-grained (by chondritic standards). This is especially the case considering that quartz and K-feldspar are very rare minerals in ordinary chondrites. Representative analyses of minerals from some granitoidal clasts are given. Based on the mineral compositions and the modal abundances the bulk compositions were calculated. Besides these granitoidal rocks, pyroxene-rich fragments occur that

  14. The Thermal Expansion Of Feldspars

    NASA Astrophysics Data System (ADS)

    Hovis, G. L.; Medford, A.; Conlon, M.

    2009-12-01

    Hovis and others (1) investigated the thermal expansion of natural and synthetic AlSi3 feldspars and demonstrated that the coefficient of thermal expansion (α) decreases significantly, and linearly, with increasing room-temperature volume (VRT). In all such feldspars, therefore, chemical expansion limits thermal expansion. The scope of this work now has been broadened to include plagioclase and Ba-K feldspar crystalline solutions. X-ray powder diffraction data have been collected between room temperature and 925 °C on six plagioclase specimens ranging in composition from anorthite to oligoclase. When combined with thermal expansion data for albite (2,3,4) a steep linear trend of α as a function of VRT emerges, reflecting how small changes in composition dramatically affect expansion behavior. The thermal expansion data for five synthetic Ba-K feldspars ranging in composition from 20 to 100 mole percent celsian, combined with data for pure K-feldspar (3,4), show α-VRT relationships similar in nature to the plagioclase series, but with a slope and intercept different from the latter. Taken as a group all Al2Si2 feldspars, including anorthite and celsian from the present study along with Sr- (5) and Pb-feldspar (6) from other workers, show very limited thermal expansion that, unlike AlSi3 feldspars, has little dependence on the divalent-ion (or M-) site occupant. This apparently is due to the necessitated alternation of Al and Si in the tetrahedral sites of these minerals (7), which in turn locks the tetrahedral framework and makes the M-site occupant nearly irrelevant to expansion behavior. Indeed, in feldspar series with coupled chemical substitution it is the change away from a 1:1 Al:Si ratio that gives feldspars greater freedom to expand. Overall, the relationships among α, chemical composition, and room-temperature volume provide useful predictive tools for estimating feldspar thermal expansion and give insight into the controls of expansion behavior in

  15. An FTIR Calibration for Structural Hydrogen in Feldspars Using 1H MAS NMR

    NASA Astrophysics Data System (ADS)

    Johnson, E. A.; Rossman, G. R.

    2002-05-01

    It is important to know how to determine the speciation and concentration of H in feldspars because this information could be used to determine primary magmatic water activity or to estimate the degree of hydrothermal alteration in igneous rocks. FTIR spectroscopy is sensitive to changes in speciation of hydrogen, and can be calibrated for quantitative determination of H concentration using 1H MAS (magic-angle spinning) NMR spectroscopy. Three pegmatitic albites, one metamorphic albite, three volcanic plagioclases (albite, andesine, and anorthite) and one pegmatite oligoclase were used in this study to provide a range of plagioclase compositions. Two pegmatitic microclines and one sanidine were also studied. Polarized infrared spectra were obtained in the three principal optical directions for each specimen. Samples were prepared for 1H MAS NMR experiments at 12 kHz spinning speed in a dry box, without the use of a liquid grinding aid. A spectrum from anhydrous synthetic corundum was used as a baseline for feldspar NMR spectra. The pegmatitic and metamorphic albites are transparent, but contain submicroscopic fluid inclusions as evidenced by a broad band at 3400 cm-1 and an asymmetric band at 5200 cm-1 in the IR spectra that shift to bands characteristic of ice upon cooling to 77 K. These albites have a very sharp band at 4.7 ppm (relative to TMS) in their NMR spectra consistent with fluid inclusion water. In addition to the broad fluid inclusion band, the pegmatitic albites have sharp bands in the mid-IR similar the OH bands found in quartz. All other plagioclases have broad, anisotropic bands around 3200 cm-1 in the mid-IR and MOH combination stretch-bend bands near 4500 cm-1 in the near-IR, indicative of structural OH. The NMR spectra of these plagioclases have a broad band at 4.7 to 4.9 ppm TMS. The OH vector in plagioclases is preferentially aligned parallel to the a crystallographic axis. The concentration of structural OH in the plagioclases ranges from 50

  16. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction

    SciTech Connect

    Stastna, A.; Sachlova, S.; Pertold, Z.; Prikryl, R.; Leichmann, J.

    2012-03-15

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  17. Energy related studies utilizing K-feldspar thermochronology

    SciTech Connect

    Not Available

    1993-01-01

    Two distinct sources of information are available from a [sup 40]Ar/[sup 39]Ar step-heating experiment: the age spectrum and Arrhenius plot. Model ages are calculated from the flux of radiogenic argon ([sup 40]Ar*) (assuming trapped argon of atmospheric composition) relative to the reactor produced [sup 39]Ar evolved during discrete laboratory heating steps. With the additional assumption that the [sup 39]Ar is uniformly distributed within the sample, we can infer the spatial distribution of the daughter product. ne associated Arrhenius plot, derived by plotting the diffusion coefficient (obtained from the inversion of the 39[sup Ar] release function assuming a single domain) against the inverse temperature of laboratory heating, are a convolution of the parameters which characterize the individual diffusion domains (whether these be dictated by varying length scale, energetics, etc.). However, many and perhaps Most [sup 40]Ar/[sup 39]Ar age spectra for slowly cooled alkali feldspars are significantly different from model age spectra calculated assuming a single diffusion-domain size. In addition, Arrhenius plots calculated from the measured loss of [sup 39]Ar during the step heating experiment show departures from linearity that are inconsistent with diffusion from domains of equal size. By extending the single diffusion-domain closure model (Dodsontype) to apply to minerals with a discrete distribution of domain sizes, we obtained an internally consistent explanation for the commonly observed features of alkali feldspar age spectra and their associated Arrhenius plots.

  18. Exchange of Na+ and K+ between water vapor and feldspar phases at high temperature and low vapor pressure

    USGS Publications Warehouse

    Fournier, R.O.

    1976-01-01

    In order to determine whether gas (steam) containing a small amount of dissolved alkali chloride is effective in promoting base exchange of Na+ and K+ among alkali feldspars and coexisting brine or brine plus solid salt, experiments were carried out at 400-700??C and steam densities ranging down to less than 0.05. For bulk compositions rich in potassium, the low pressure results are close to previous high-pressure results in composition of the fluid and coexisting solid phase. However, when the bulk composition is more sodic, alkali feldspars are relatively richer in potassium at low pressure than at high pressure. This behaviour corresponds to enrichment of potassium in the gas phase relative to coexisting brine and precipitation of solid NaCl when the brine plus gas composition becomes moderately sodic. The gas phase is very effective in promoting base exchange between coexisting alkali feldspars at high temperature and low water pressure. This suggests that those igneous rocks which contain coexisting alkali feldspars out of chemical equilibrium either remained very dry during the high-temperature part of their cooling history or that the pore fluid was a gas containing very little potassium relative to sodium. ?? 1976.

  19. Alteration and fluid flow around a sulfide-carbonate-quartz vein, Lucky Friday mine, Northern Idaho

    SciTech Connect

    Gitlin, E.C.

    1985-01-01

    Wall rocks at the Lucky Friday mine, Coeur d'Alene district, Idaho, contain a >500m wide zone about a steeply dipping Pb-Zn-Ag vein. This zone has experienced local conditions distinct from the regional metamorphism of the quartzite + argillite host rock. Within the district, the host rock (Precambrian Revett Formation) has undergone low grade metamorphism and contains varying proportions of quartz, phengitic muscovite, detrital alkali feldspar, magnetite, hematite, ilmenite, rutile, zircon, tourmaline, +/- calcite, +/- ankeritic dolomite. In contrast, the Lucky Friday wall rocks lack feldspar and Fe-bearing oxides, and contain Fe-poor muscovite and up to 40% carbonate: siderite, ankerite, and/or calcite. A comparison of district-wide Revett rocks with Lucky Friday wall rocks suggests that the wall rocks have undergone localized dephengitization with concomitant Fe-enrichment in the carbonates and Fe-depletion of the oxides. Pertinent metamorphic reactions consume CO/sub 2/ and liberate H/sub 2/O. Fluid inclusions from the vein and wall rock stringers have homogenization temperatures from approx. =200/sup 0/ to <375/sup 0/C, but they define no temperature gradient. With few exceptions, compositions of the carbonates are identical throughout the altered wall rock. These observations suggest that the carbonate subzone contacts are not isograds but isofluxes: the loci of equivalent fluid/reactant mineral ratio. The disposition of isofluxes around a dominant fluid channelway, i.e. the vein, affords an opportunity to interpret fluid flow pathways during low temperatures metamorphism.

  20. Argon Diffusion in Shocked Pyroxene, Feldspar, and Olivine

    NASA Astrophysics Data System (ADS)

    Weirich, J.; Isachsen, C. E.; Johnson, J. R.; Swindle, T.

    2010-12-01

    low activation energy, somewhat similar to that of unshocked alkali feldspar, despite remaining a high temperature mineral due to a much lower frequency factor. References: [1]Jessberger E. K. and Ostertag R. (1982). GCA 46:1465-1471. [2]Stephan T. and Jessberger E. K. (1992). GCA 56:1591-1605.

  1. Comparative Petrographic Maturity of River and Beach Sand, and Origin of Quartz Arenites.

    ERIC Educational Resources Information Center

    Ferree, Rob A.; And Others

    1988-01-01

    Describes a deterministic computer model that incorporates: (1) initial framework composition; (2) abrasion factors for quartz, feldspar, and rock fragments; and (3) a fragmentation ratio for rock fragments to simulate the recycling of coastal sands by rivers and beaches. (TW)

  2. Thermodynamic Mixing Properties of Rb-K-Na Feldspars and Relevance to Rb-, NH4-, K-, Na-, and Li-Feldspar Thermal Expansion

    NASA Astrophysics Data System (ADS)

    Hovis, G. L.; Morabito, J.; Mott, A.

    2006-12-01

    We have investigated a ten-member Rb-K feldspar solid solution series having an ordered Al-Si distribution. Rb-microcline, or rubicline, was synthesized via repeated ion exchange experiments of microcline in molten RbCl. This resulted in Rb-feldspar containing ~92 mol percent Rb, which appears to be the maximum amount of Rb that ordered feldspars can take up using ion-exchange techniques at 1 kbar. [Similarly synthesized Al-Si disordered Rb-feldspar is even more limited in Rb content (Kovalskii and Kotelnikov, EMPG IX, 2002).] Compositions between 0 and 92 mol percent Rb were synthesized by combining rubicline and microcline in the desired molar proportions, then chemically homogenizing the samples at elevated temperature. Enthalpies of solution (20.1 wt percent HF, 50 °C, isoperibolic conditions) for the series are nearly linear with composition, with the possibility of low-magnitude positive enthalpies of Rb-K mixing at Rb-rich compositions. This behavior contrasts sharply with the considerably greater enthalpies of mixing in K-Na feldspars (Hovis, 1986, Journal of Petrology). Feldspars, therefore, which have but a single alkali site, exhibit larger enthalpies of mixing when there is a clear contrast in the sizes of the ions occupying that site. This is not surprising in light of the tendency of chemically homogeneous K-Na feldspars to undergo exsolution with cooling. In the case of the Rb end member, the feldspar structure appears to be stretched nearly to its limit. This is reflected by the coefficients of thermal expansion for Rb, NH4, K, Na and Li feldspar end members (all of which we have measured) that show a linear relationship with room-temperature unit-cell volume: The larger the unit cell at room temperature, the less potential there is for thermal expansion. [Similar relations are found as a function of K:Na in nepheline - kalsilite framework silicates (Hovis and others, Mineralogical Magazine, 2003).] Thus, even at room temperature the Rb-feldspar

  3. Atmospheric weathering and silica-coated feldspar: Analogy with zeolite molecular sieves, granite weathering, soil formation, ornamental slabs, and ceramics

    PubMed Central

    Smith, Joseph V.

    1998-01-01

    Feldspar surfaces respond to chemical, biological, and mechanical weathering. The simplest termination is hydroxyl (OH), which interacts with any adsorption layer. Acid leaching of alkalis and aluminum generated a silica-rich, nanometers-thick skin on certain feldspars. Natural K, Na-feldspars develop fragile surfaces as etch pits expand into micrometer honeycombs, possibly colonized by lichens. Most crystals have various irregular coats. Based on surface-catalytic processes in molecular sieve zeolites, I proposed that some natural feldspars lose weakly bonded Al-OH (aluminol) to yield surfaces terminated by strongly bonded Si-OH (silanol). This might explain why some old feldspar-bearing rocks weather slower than predicted from brief laboratory dissolution. Lack of an Al-OH infrared frequency from a feldspar surface is consistent with such a silanol-dominated surface. Raman spectra of altered patches on acid-leached albite correspond with amorphous silica rather than hydroxylated silica–feldspar, but natural feldspar may respond differently. The crystal structure of H-exchanged feldspar provides atomic positions for computer modeling of complex ideas for silica-terminated feldspar surfaces. Natural weathering also depends on swings of temperature and hydration, plus transport of particles, molecules, and ionic complexes by rain and wind. Soil formation might be enhanced by crushing granitic outcrops to generate new Al-rich surfaces favorable for chemical and biological weathering. Ornamental slabs used by architects and monumental masons might last longer by minimizing mechanical abrasion during sawing and polishing and by silicifying the surface. Silica-terminated feldspar might be a promising ceramic surface. PMID:9520371

  4. Feldspar concentrations in lower Cambrian limestones of the Moroccan Atlas: Pyroclastic vs authigenic processes

    NASA Astrophysics Data System (ADS)

    Álvaro, J. Javier; Bauluz, Blanca

    2008-02-01

    Carbonate strata containing abundant euhedral feldspar, usually considered as authigenic, are characteristic of some lower Cambrian exposures in the Atlas Mountains, Morocco. Impure limestones are abundant in the Issendalenian Amouslek Formation of the western Anti-Atlas, and in the Banian Lemdad Formation of the southern High Atlas. Some of their limestone beds contain up to 40% acid insoluble residue, of which feldspar comprises as much as 65% in some samples, the remainder consisting of detrital and authigenic quartz, apatite, pyrite, and clay minerals. The host limestones are bioclastic tempestites, ooidal-oncoidal-bioclastic shoal complexes, archaeocyathan-microbial peri-reef settings (mainly flanks but not reef cores), and microbial reefs. A volcanic origin is adopted for the feldspars based on: (i) fluctuations in feldspar concentration paralleling bedding, but unrelated to host-facies (except for the aforementioned archaeocyathan-microbial reef cores that were controlled by turbidity); (ii) the local association with glassy fragments (with feldspars embedded in glass shards); and (iii) the scattered occurrence of gradational lithofacies from silty tuff to tuffitic limestone. The mineral and chemical composition of the host-rock and diagenetic fluids was the determining factor for the kind of feldspar preservation. Although the primary type of K-feldspar replacement is albitization, secondary albite subsequently suffered from illitization, chloritization, and/or replacement by calcite. A direct implication of this work is the possible geochronological dating of both volcanic eruptions and archaeocyath- and trilobite-bearing host-rocks based on radiometric analyses within unaltered K-feldspar pyroclasts extracted after etching.

  5. Secondary porosity revisited: The chemistry of feldspar dissolution by carboxylic acids and anions

    SciTech Connect

    Stoessell, R.K. ); Pittman, E.D. )

    1990-12-01

    Carboxylic acids in subsurface waters have been proposed as agents for dissolving feldspars and complexing aluminum to create secondary porosity in sandstones. Previously published experimental work indicated high aluminum mobility in the presence of carboxylic acid solutions. In order to further evaluate aluminum mobility, alkali feldspar dissolution experiments were run at 100C and 300 bars in the presence of mono- and dicarboxylic acids and their anions. Experimental results imply that under reservoir conditions, aluminum-organic anion complexes are insignificant for acetate and propionate and possibly significant for oxalate and malonate. Propionate appeared to inhibit alkali feldspar dissolution and, hence, may retard aluminum mobility. Dissolution of feldspar in the presence of oxalic and acetic acid can be explained by enhanced dissolution kinetics and greater aluminum mobility under low-pH conditions. The general absence of such low-pH fluids in subsurface reservoirs makes this an unlikely mechanism for creating secondary porosity. Also, the thermal instability of oxalate and malonate limits their aluminum-complexing potential in reservoirs at temperatures above 100C.

  6. Systematic variations of argon diffusion in feldspars and implications for thermochronometry

    DOE PAGESBeta

    Cassata, William S.; Renne, Paul R.

    2013-03-07

    Coupled information about the time-dependent production and temperature-dependent diffusion of radiogenic argon in feldspars can be used to constrain the thermal evolution attending a host of Earth and planetary processes. To better assess the accuracy of thermal models, an understanding of the mechanisms and pathways by which argon diffuses in feldspars is desirable. Here we present step-heating Ar diffusion experiments conducted on feldspars with diverse compositions, structural states, and microstructural characteristics. The experiments reveal systematic variations in diffusive behavior that appear closely related to these variables, with apparent closure temperatures for 0.1–1 mm grains of ~200–400 °C (assuming a 10more » °C/Ma cooling rate). Given such variability, there is no broadly applicable set of diffusion parameters that can be utilized in feldspar thermal modeling; sample-specific data are required. Diffusion experiments conducted on oriented cleavage flakes do not reveal directionally-dependent diffusive anisotropy to within the resolution limits of our approach (approximately a factor of 2). Additional experiments aimed at constraining the physical significance of the diffusion domain are presented and indicate that unaltered feldspar crystals with or without coherent exsolution lamellae diffuse at the grain-scale, whereas feldspars containing hydrothermal alteration and/or incoherent sub-grain intergrowths do not. Arrhenius plots for argon diffusion in plagioclase and alkali feldspars appear to reflect a confluence of intrinsic diffusion kinetics and structural transitions that occur during incremental heating experiments. These structural transitions, along with sub-grain domain size variations, cause deviations from linearity (i.e., upward and downward curvature) on Arrhenius plots. An atomistic model for Arrhenius behavior is proposed that incorporates the variable lattice deformations of different feldspars in response to heating and

  7. Systematic variations of argon diffusion in feldspars and implications for thermochronometry

    SciTech Connect

    Cassata, William S.; Renne, Paul R.

    2013-03-07

    Coupled information about the time-dependent production and temperature-dependent diffusion of radiogenic argon in feldspars can be used to constrain the thermal evolution attending a host of Earth and planetary processes. To better assess the accuracy of thermal models, an understanding of the mechanisms and pathways by which argon diffuses in feldspars is desirable. Here we present step-heating Ar diffusion experiments conducted on feldspars with diverse compositions, structural states, and microstructural characteristics. The experiments reveal systematic variations in diffusive behavior that appear closely related to these variables, with apparent closure temperatures for 0.1–1 mm grains of ~200–400 °C (assuming a 10 °C/Ma cooling rate). Given such variability, there is no broadly applicable set of diffusion parameters that can be utilized in feldspar thermal modeling; sample-specific data are required. Diffusion experiments conducted on oriented cleavage flakes do not reveal directionally-dependent diffusive anisotropy to within the resolution limits of our approach (approximately a factor of 2). Additional experiments aimed at constraining the physical significance of the diffusion domain are presented and indicate that unaltered feldspar crystals with or without coherent exsolution lamellae diffuse at the grain-scale, whereas feldspars containing hydrothermal alteration and/or incoherent sub-grain intergrowths do not. Arrhenius plots for argon diffusion in plagioclase and alkali feldspars appear to reflect a confluence of intrinsic diffusion kinetics and structural transitions that occur during incremental heating experiments. These structural transitions, along with sub-grain domain size variations, cause deviations from linearity (i.e., upward and downward curvature) on Arrhenius plots. An atomistic model for Arrhenius behavior is proposed that incorporates the variable lattice deformations of different feldspars in response to heating and

  8. Raman Spectroscopic Characterization of the Feldspars: Implications for Surface Mineral Characterization in Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Freeman, J. J.; Wang, Alian; Kuebler, K. E.; Haskin, L. A.

    2003-01-01

    The availability in the last decade of improved Raman instrumentation using small, stable, intense lasers, sensitive CCD array detectors, and advanced fast grating systems enabled us to develop the Mars Microbeam Raman Spectrometer (MMRS), a field-portable Raman spectrometer with precision and accuracy capable of identifying minerals and their different compositions. For example, we can determine Mg cation ratios in pyroxenes and olivines to +/-0.1 on the basis of Raman peak positions. Feldspar is another major mineral formed in igneous systems whose characterization is important for determining rock petrogenesis and alteration. From their Raman spectral pattern, feldspars can be readily distinguished from ortho- and chain-silicates and from other tecto-silicates such as quartz and zeolites. We show here how well Raman spectral analysis can distinguish among members within the feldspar group.

  9. Authigenic K-feldspar in salt rock (Haselgebirge Formation, Eastern Alps)

    NASA Astrophysics Data System (ADS)

    Leitner, Christoph

    2015-04-01

    The crystallisation of authigenic quartz under low temperature, saline conditions is well known (Grimm, 1962). Also the growth of low temperature authigenic feldspar in sediments is a long known phenomenon (Kastner & Siever, 1979; Sandler et al., 2004). In this study we intend to show that halite (NaCl) is a major catalyser for authigenic mineral growth. During late Permian (c. 255-250 Ma), when the later Eastern Alps were located around north of the equator, the evaporites of the Haselgebirge Formation were deposited (Piller et al., 2004). The Haselgebirge Fm. consists in salt mines of a two-component tectonite of c. 50 % halite and 50 % sedimentary clastic and other evaporite rocks (Spötl 1998). Most of the clastic rocks are mud- to siltstones ("mudrock"). During this study, we investigated rare sandstones embedded in salt rock form four Alpine salt mines. Around 40 polished thin sections were prepared by dry grinding for thin section analysis and scanning electron microscopy. The sandstones consist mainly of quartz, K-feldspar, rock fragments, micas, accessory minerals and halite in the pore space. They are fine grained and well sorted. Mudrock clasts in sandstone were observed locally, and also coal was observed repeatedly. Asymmetric ripples were found only in the dimension of millimeters to centimeters. Euhedral halite crystals in pores indicate an early presence of halite. During early diagenesis, authigenic minerals crystallized in the following chronological order. (1) Where carbonate (mainly magnesite) occurred, it first filled the pore space. Plant remains were impregnated with carbonate. (2) Halite precipitated between the detritic sandstone grains. Carbonate grains can be completely embedded in halite. (3) K-feldspar and quartz grains usually expose a detritic core and a later grown euhedral inclusion free rim. Euhedral rims of K-feldspar often also enclose a halite core. K-feldspar replaced the pre-existing halite along former grain boundaries of

  10. Preferential cataclastic grain size reduction of feldspar in deformation bands in poorly consolidated arkosic sands

    NASA Astrophysics Data System (ADS)

    Exner, Ulrike; Tschegg, Cornelius

    2012-10-01

    This study presents microstructural as well as bulk and mineral chemical investigations of deformation bands in uncemented, friable arkosic sands of Miocene age (Vienna Basin, Austria). Our microstructural study indicates grain size reduction by grain flaking in deformation bands with small offsets (0.5-8 cm), and dominant intragranular fracturing and cataclasis of altered feldspar grains at larger displacements (up to 60 cm). Relative to quartz, the sericitized feldspar grains are preferably fractured and abraded, which additionally leads to an enrichment of mainly phyllosilicates by mechanical expulsion from feldspar. Both cataclasis of quartz and feldspar grains and enrichment of phyllosilicates result in grain size reduction within the deformation bands. The measured reduction in porosity of up to 20% is in some cases associated with a permeability reduction, reflected in the retention of iron-oxide rich fluids along deformation bands. These deformation bands formed at very shallow burial depths in unconsolidated sediments indicate that fault sealing may occur in the absence of chemical alteration of the deformation bands and lead to a compartmentalization of a groundwater or hydrocarbon reservoir.

  11. Preferential cataclastic grain size reduction of feldspar in deformation bands in poorly consolidated arkosic sands

    PubMed Central

    Exner, Ulrike; Tschegg, Cornelius

    2012-01-01

    This study presents microstructural as well as bulk and mineral chemical investigations of deformation bands in uncemented, friable arkosic sands of Miocene age (Vienna Basin, Austria). Our microstructural study indicates grain size reduction by grain flaking in deformation bands with small offsets (0.5–8 cm), and dominant intragranular fracturing and cataclasis of altered feldspar grains at larger displacements (up to 60 cm). Relative to quartz, the sericitized feldspar grains are preferably fractured and abraded, which additionally leads to an enrichment of mainly phyllosilicates by mechanical expulsion from feldspar. Both cataclasis of quartz and feldspar grains and enrichment of phyllosilicates result in grain size reduction within the deformation bands. The measured reduction in porosity of up to 20% is in some cases associated with a permeability reduction, reflected in the retention of iron-oxide rich fluids along deformation bands. These deformation bands formed at very shallow burial depths in unconsolidated sediments indicate that fault sealing may occur in the absence of chemical alteration of the deformation bands and lead to a compartmentalization of a groundwater or hydrocarbon reservoir. PMID:26523078

  12. In situ feldspar dissolution rates in an aquifer

    NASA Astrophysics Data System (ADS)

    Zhu, Chen

    2005-03-01

    In situ silicate dissolution rates within the saturated Navajo sandstone, at Black Mesa, Arizona were determined from elemental fluxes in the aquifer. The mass transfer between groundwater and mineral matrix along flow paths was calculated from inverse mass balance modeling. The reaction time is bound by 14C-based travel time. BET surface areas were measured with N 2 gas adsorption. Dissolution rates for K-feldspar and plagioclase are 10 -19 and 10 -16 mol (feldspar) m -2 s -1, respectively, which are ˜10 5 times slower than laboratory experiment-derived rates under similar pH and temperature but at far from equilibrium conditions. The rates obtained in this study are consistent with the slower field rates found in numerous watershed and soil profile studies. However, these rates are from saturated aquifers, overcoming some concerns on estimated rates from unsaturated systems. The Navajo sandstone is a quartz-sandstone with a relatively simple and well-studied hydrogeology, groundwater geochemistry, and lithology, a large number of groundwater analyses and 14C groundwater ages, groundwater residence times up to ˜37 ky, groundwater pH from ˜8 to 10, and temperature from ˜15 to 35°C.

  13. Shock effects in plagioclase feldspar from the Mistastin Lake impact structure, Canada

    NASA Astrophysics Data System (ADS)

    Pickersgill, Annemarie E.; Osinski, Gordon R.; Flemming, Roberta L.

    2015-09-01

    Shock metamorphism, caused by hypervelocity impact, is a poorly understood process in feldspar due to the complexity of the crystal structure, the relative ease of weathering, and chemical variations, making optical studies of shocked feldspars challenging. Understanding shock metamorphism in feldspars, and plagioclase in particular, is vital for understanding the history of Earth's moon, Mars, and many other planetary bodies. We present here a comprehensive study of shock effects in andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada. Samples from a range of different settings were studied, from in situ central uplift materials to clasts from various breccias and impact melt rocks. Evidence of shock metamorphism includes undulose extinction, offset twins, kinked twins, alternate twin deformation, and partial to complete transformation to diaplectic plagioclase glass. In some cases, isotropization of alternating twin lamellae was observed. Planar deformation features (PDFs) are notably absent in the plagioclase, even when present in neighboring quartz grains. It is notable that various microlites, twin planes, and compositionally different lamellae could easily be mistaken for PDFs and so care must be taken. A pseudomorphous zeolite phase (levyne-Ca) was identified as a replacement mineral of diaplectic feldspar glass in some samples, which could, in some instances, also be potentially mistaken for PDFs. We suggest that the lack of PDFs in plagioclase could be due to a combination of structural controls relating to the crystal structure of different feldspars and/or the presence of existing planes of weakness in the form of twin and cleavage planes.

  14. Biochemical evolution II: origin of life in tubular microstructures on weathered feldspar surfaces.

    PubMed

    Parsons, I; Lee, M R; Smith, J V

    1998-12-22

    Mineral surfaces were important during the emergence of life on Earth because the assembly of the necessary complex biomolecules by random collisions in dilute aqueous solutions is implausible. Most silicate mineral surfaces are hydrophilic and organophobic and unsuitable for catalytic reactions, but some silica-rich surfaces of partly dealuminated feldspars and zeolites are organophilic and potentially catalytic. Weathered alkali feldspar crystals from granitic rocks at Shap, north west England, contain abundant tubular etch pits, typically 0.4-0.6 microm wide, forming an orthogonal honeycomb network in a surface zone 50 microm thick, with 2-3 x 10(6) intersections per mm2 of crystal surface. Surviving metamorphic rocks demonstrate that granites and acidic surface water were present on the Earth's surface by approximately 3.8 Ga. By analogy with Shap granite, honeycombed feldspar has considerable potential as a natural catalytic surface for the start of biochemical evolution. Biomolecules should have become available by catalysis of amino acids, etc. The honeycomb would have provided access to various mineral inclusions in the feldspar, particularly apatite and oxides, which contain phosphorus and transition metals necessary for energetic life. The organized environment would have protected complex molecules from dispersion into dilute solutions, from hydrolysis, and from UV radiation. Sub-micrometer tubes in the honeycomb might have acted as rudimentary cell walls for proto-organisms, which ultimately evolved a lipid lid giving further shelter from the hostile outside environment. A lid would finally have become a complete cell wall permitting detachment and flotation in primordial "soup." Etch features on weathered alkali feldspar from Shap match the shape of overlying soil bacteria. PMID:9860941

  15. Thermal expansion of plagioclase feldspars

    NASA Astrophysics Data System (ADS)

    Tribaudino, M.; Angel, R. J.; Cámara, F.; Nestola, F.; Pasqual, D.; Margiolaki, I.

    2010-12-01

    The volume thermal expansion coefficient and the anisotropy of thermal expansion were determined for nine natural feldspars with compositions, in terms of albite (NaAlSi3O8, Ab) and anorthite (CaAl2Si2O8, An), of Ab100, An27Ab73, An35Ab65, An46Ab54, An60Ab40, An78Ab22, An89Ab11, An96Ab4 and An100 by high resolution powder diffraction with a synchrotron radiation source. Unit-cell parameters were determined from 124 powder patterns of each sample, collected over the temperature range 298-935 K. The volume thermal expansion coefficient of the samples determined by a linear fit of V/ V 0 = α( T - T 0) varies with composition ( X An in mol %) as: αV = 2.90left( 4 right) × 10^{ - 5} - 3.0left( 2 right) × 10^{ - 7} *X_{text{An}} + 1.8left( 2 right) × 10^{ - 9} *X_{text{An}}2 Two empirical models for the non-linear behaviour of volume with temperature give a better fit to the experimental data. The change with composition in the a° parameter of the non-linear Holland-Powell model V/ V 0 = 1 + a°( T - T 0) + 20a° (√ T - √ T 0) is: a^circ = 4.96left( 5 right) × 10^{ - 5} - 4.7left( 2 right) × 10^{ - 7} *X_{text{An}} + 2.2left( 2 right) × 10^{ - 9} *X_{text{An}}2 For the Berman model, V/ V 0 = a 1( T - T 0) + a 2*( T- T 0)2, the parameters change with composition as: begin{aligned}& a1 = 2.44left( {15} right) × 10^{ - 5} - 3.1left( 6 right) × 10^{ - 7} *X_{text{An}}\\& quad + 1.8left( 5 right) × 10^{ - 9} *X_{text{An}}2 \\& a2 = 9left( 1 right) × 10^{ - 9} - 4left( 2 right) × 10^{ - 11} *X_{text{An}} \\ The thermal expansion of all plagioclases is very anisotropic, with more than 70% of the volume expansion being accommodated by a direction fairly close to the (100) plane normal, whereas perpendicular directions exhibit smaller, and in some cases slightly negative or zero, thermal expansion.

  16. Alkali Bee

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The alkali bee, Nomia melanderi, is native to deserts and semi-arid desert basins of the western United States. It is a very effective and manageable pollinator for the production of seed in alfalfa (=lucerne) and some other crops, such as onion. It is the world’s only intensively managed ground-n...

  17. Deformation behaviour of feldspar in greenschist facies granitoide shear zones from the Austroalpine basement to the south of the western Tauern window, Eastern Alps

    NASA Astrophysics Data System (ADS)

    Hentschel, Felix; Trepmann, Claudia

    2015-04-01

    Objective of this study is to elucidate the feldspar deformation behaviour at greenschist facies conditions relevant for the long-term rheological properties of continental crust. Uncertainties in models for the rheological properties are partly due to a poor knowledge of the deformation mechanisms taking place in granitoid rocks at inaccessible depth. The deformation behaviour of feldspar, the most abundant mineral in the continental crust, is characterized by an interaction of brittle, dissolution-precipitation and crystal-plastic processes, which is difficult to evaluate in experiments given the problematic extrapolation of experimental conditions to reasonable natural conditions. However, microfabrics of metamorphic granitoid rocks record the grain-scale deformation mechanisms and involved chemical reactions proceeding during their geological history. This usually includes deformation and modification through several stages in space (depth, i.e., P, T conditions) and/or time. For deciphering the rock's record this implies both, challenge and chance to resolve these different stages. Here, we use the deformation record of mylonitic pegmatites from the Austroalpine basement south to the western Tauern window. The structural, crystallographic and chemical characteristics of the feldspar microfabrics are determined via micro-analytical techniques (polarized light microscopy, scanning electron microscopy, SEM, electron back scatter diffraction, EBSD) to identify the relevant deformation mechanisms and deformation conditions. The pegmatites represent a relatively simple Ca-poor granitoid system, mineralogically dominated by albite-rich plagioclase, K-feldspar and quartz. The matrix of the mylonitic pegmatites is composed of alternating monomineralic albite and quartz ribbons defining the foliation. Fragmented tourmaline and K-feldspar porphyroclasts occur isolated within the matrix. At sites of dilation along the stretching lineation K-feldspar porphyroclasts show

  18. Quartz ball value

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M.

    1979-01-01

    Quartz ball valve consisting of two quartz joints sealed back-to-back and seated in quartz sockets perform at temperatures of up to 1,250 C and in corrosive chemical environments without contamination or degradation.

  19. Characterization and Thermodynamics Studies of Feldspar and Feldspathoid Minerals

    NASA Astrophysics Data System (ADS)

    Rudow, M.; Lilova, K.

    2015-12-01

    The application of thermal analysis and calorimetry for the studies of minerals has a history as long as the existence of the thermal methods themselves. New advanced calorimetric techniques have been developed for more accurate characterization of both bulk and nano materials thus impacting their design, processing, and applications. TG-DTA and TG-DSC are used to characterize the composition of complex minerals (e.g. [KxNa1-x(AlSi3)O8]) based on the weight changes and phase transformations observed with temperature increase. Additionally, those techniques allow to determine the quantity of the different types of water contained in natural feldspars and feldspathoids (absorbed, interlayer, structural). The results for several clays will be discussed. The geochemical properties and thermal stability of another class of minerals - aluminosilicate frameworks (alkali sodalities, natrolites, etc.) as related to high-level nuclear waste treatment facilities, radioactive waste storage and management were studied. The natural sodalite Na8[Al6Si6O24]Cl2 and similar frameworks with different anions are part of sodium-aluminosilicate (NAS) low activity radioactive waste produced during steam reforming process treatment. The enthalpies and entropies of formation and the hydration enthalpies of the above-mentioned feltspathoids are obtained and the effect of the different cations and anions on the thermodynamic stability was studied. The results will allow to predict the long term behavior of the compounds in the environment under different conditions.

  20. Brittle grain-size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, Gustavo; Menegon, Luca; Archanjo, Carlos

    2016-03-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse-grained (> 50 µm) feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (< 15 µm) localized in C' shear bands. Detailed microstructural observations and electron backscatter diffraction (EBSD) analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (˜ 1-2 mm) monomineralic veins transposed along the shear zone foliation or as thin ribbons ( ≤ 25 µm width) dispersed in the feldspathic mixture. The microstructure and c axis crystallographic-preferred orientation are similar in the thick monomineralic veins and in the thin ribbons, and they suggest dominant subgrain rotation recrystallization and activity of prism < a > and rhomb < a > slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the quartz monomineralic veins to the thin ribbons embedded in the feldspathic C' bands (14 µm vs. 5 µm respectively). The fine-grained feldspar mixture has a weak crystallographic-preferred orientation interpreted as the result of shear zone parallel-oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Once C' shear bands were generated and underwent viscous deformation at constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate 1 order of magnitude faster than the monophase quartz monomineralic veins, as evidenced by applying experimentally and theoretically calibrated flow laws for dislocation creep in quartz and diffusion creep in

  1. The surface chemistry of dissolving labradorite feldspar

    NASA Astrophysics Data System (ADS)

    Casey, William H.; Westrich, Henry R.; Arnold, George W.; banfield, Jillian F.

    1989-04-01

    Elastic recoil detection (ERD) analysis was used in conjunction with Rutherford backscattering (RBS) analysis to determine depth profiles of hydrogen, silicon, aluminum and calcium in labradorite crystals reacted under various pH conditions. The inventory of hydrogen in the mineral is strongly affected by solution pH. Hydrogen extensively infiltrates the mineral during reaction for 264 hours with solutions in the pH range 1-3. Infiltration is accompanied by extensive removal of sodium, calcium and aluminum from the mineral. This incongruent reaction proceeds to several hundreds of angstroms of depth and produces a silicon-rich surface which is amorphous to electron diffraction. The amount of hydrogen in the reacted layer is much less than is predicted from knowledge of the quantity of cations leached from the feldspar. These low inventories of hydrogen suggest that hydrogen-bearing groups in the reacted layer repolymermize subsequent to ion exchange and depolymerization reactions. This repolymerization eliminates hydrogen from the layer. At higher pH conditions (pH > 5), hydrogen inventories in the crystals decrease with time relative to an unreacted reference crystal. Hydrogen does not infiltrate beyond the first few unit cells of feldspar. Thus, dissolution in slightly acid, near-neutral, and basic solutions proceeds at the immediate surface of the feldspar. Within the limit of the RBS technique, there is no evidence for incongruent dissolution at these conditions.

  2. Shock melting of K-feldspar and interlacing with cataclastically deformed plagioclase in granitic rocks at Toqqusap Nunaa, southern West Greenland: Implications for the genesis of the Maniitsoq structure

    NASA Astrophysics Data System (ADS)

    Keulen, Nynke; Garde, Adam A.; Jørgart, Tommy

    2015-11-01

    Folded sheets of Mesoarchaean, leucocratic plagioclase-K-feldspar-mesoperthite-bearing granitic rocks in the Toqqusap Nunaa area of the Maniitsoq structure, West Greenland, are characterised by their very fine grain sizes and microstructures without normal igneous or planar/linear tectonic fabrics. Quartz forms equidimensional and branching, ductilely deformed aggregates and bifurcating panels with protrusions, constrictions and chains of ball-shaped grains with healed, radiating intergranular fractures. Plagioclase (An10-20) was cataclastically deformed and comminuted, whereas K-feldspar and mesoperthite are devoid of cataclastic microstructures. K-feldspar forms dispersed, highly irregular grains with numerous cusps and saddles, indicating almost ubiquitous direct (shock) melting of this mineral. It is commonly located along former fractures in plagioclase, resulting in an 'interlaced' feldspar microstructure with contact shapes indicating subsequent melting of plagioclase directly adjacent to K-feldspar. Mesoperthite forms separate, rounded, and irregular grains with protrusions and cusped margins indicating crystallisation from melts. Some mesoperthite grains are texturally and compositionally heterogeneous and contain internal lenses of K-feldspar and/or plagioclase. Other mesoperthite grains comprise coarsened, 'unzipped' areas, presumably due to localised, fluid-controlled dissolution-reprecipitation processes. The ternary feldspar precursor of the mesoperthite is interpreted as having crystallised from variably effectively mixed K-feldspar shock melts and plagioclase contact melts. Direct melting of K-feldspar, but no whole-rock melting, requires shock metamorphism with a short-lived temperature excursion to above the melting temperature of K-feldspar (~ 1300 °C). The presence of three different feldspar species and absence of chemical zonation, magmatic mantling, or metamorphic coronas furthermore hinders interpretations solely by means of endogenic

  3. Energy related studies utilizing K-feldspar thermochronology. Progress performance report, 1990--1993

    SciTech Connect

    Not Available

    1993-05-01

    Two distinct sources of information are available from a {sup 40}Ar/{sup 39}Ar step-heating experiment: the age spectrum and Arrhenius plot. Model ages are calculated from the flux of radiogenic argon ({sup 40}Ar*) (assuming trapped argon of atmospheric composition) relative to the reactor produced {sup 39}Ar evolved during discrete laboratory heating steps. With the additional assumption that the {sup 39}Ar is uniformly distributed within the sample, we can infer the spatial distribution of the daughter product. ne associated Arrhenius plot, derived by plotting the diffusion coefficient (obtained from the inversion of the 39{sup Ar} release function assuming a single domain) against the inverse temperature of laboratory heating, are a convolution of the parameters which characterize the individual diffusion domains (whether these be dictated by varying length scale, energetics, etc.). However, many and perhaps Most {sup 40}Ar/{sup 39}Ar age spectra for slowly cooled alkali feldspars are significantly different from model age spectra calculated assuming a single diffusion-domain size. In addition, Arrhenius plots calculated from the measured loss of {sup 39}Ar during the step heating experiment show departures from linearity that are inconsistent with diffusion from domains of equal size. By extending the single diffusion-domain closure model (Dodsontype) to apply to minerals with a discrete distribution of domain sizes, we obtained an internally consistent explanation for the commonly observed features of alkali feldspar age spectra and their associated Arrhenius plots.

  4. Petrology and geochemistry of alkali gabbronorites from lunar breccia 67975

    NASA Technical Reports Server (NTRS)

    James, Odette B.; Flohr, Marta K.; Lindstrom, Marilyn M.

    1987-01-01

    Detailed results of petrologic and compositional studies of three clasts found in thin sections of the Apollo 16 lunar breccia 67975 and of four clasts extracted from the breccia (for instrumental neutron activation analysis) prior to thin sectioning are reported. The alkali gabbronorites of the breccia form two distinct subgroups, magnesian and ferroan. The magnesian gabbronorites are composed of bytownitic plagioclase, hypersthene, augite, a silica mineral, and trace Ba-rich K-feldspar. The ferroan gabbronorites are composed of ternary plagioclase, pigeonite, augite, Ba-rich K-feldspar, and a silica mineral. Trace minerals in both subgroups are apatite, REE-rich whitlockite, and zircon. The magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same, or closely related, parent REE-rich magmas.

  5. Feldspar-fluid interactions in braid microperthites: pleated rims and vein microperthites

    NASA Astrophysics Data System (ADS)

    Lee, Martin R.; Waldron, Kim A.; Parsons, I.; Brown, William L.

    Braid microperthitic alkali feldspars in the Klokken, South Greenland and Coldwell, Ontario syenite intrusions have bulk-compositional variations along grain boundaries called pleated rims. These, together with vein microperthites in aplites which cross-cut the syenites, have been investigated by SEM and TEM. We distinguish two main types of pleated rims, ``arched '' and ``parallel-sided '', consisting of alternating Ab- and Or-rich areas on (001), which are 0.5-300 μm in length normal to (010) and 0.2-20 μm in width along (010). The smallest pleats, which occur on intracrystalline boundaries in Klokken feldspars, are fully coherent and composed of low albite and low microcline. Above the heads of some of the coarser pleats, braid microperthite grades into a film crypto- and micro-perthite and antiperthite microtexture called a ``transitional zone'' containing roughly planar lamellae of low albite and tweed orthoclase. During pleat development, local alternating volumes form in which the proportions of the phases differ ( phase separation) and the morphology of the intergrowths changes from braided to straight in response to this change in local bulk composition. Straightening is also accompanied by transformation of low microcline to tweed orthoclase. The coarsest pleats, which occur along grain boundaries in feldspars from the Coldwell syenite, are semi- or in-coherent and have a thick coherent and semicoherent transitional zone. Coarsening of pleats and development of the transitional zone has been facilitated by diffusion of ``water'' into grain interiors. In many cases, pleated rims have suffered deuteric alteration, by dissolution-reprecipitation processes, through the action of a water-rich fluid from the grain boundary, in which tweed orthoclase was transformed into irregular microcline and micropores developed. Vein microperthites in aplites from Klokken, and by extension the vein microperthites almost universal in most alkali granites, are interpreted

  6. A natural example of crystal-plastic deformation enhancing the incorporation of water into quartz

    NASA Astrophysics Data System (ADS)

    Gleason, Gayle C.; DeSisto, Stephanie

    2008-01-01

    Water content of quartz in and around a greenschist facies mylonitic shear zone located in the western Adirondacks was analyzed by micro-FTIR spectroscopy. The shear zone is within a pegmatitic dike, which cuts across a granitic gneiss. The thickness of the shear zone varies along strike from 15 cm wide and encompassing all of the pegmatite dike at its northern most exposure to 5 cm wide approximately 10 m south, along strike. Microstructures, including quartz ribbons and recrystallized grains, indicate quartz and feldspar within the mylonite underwent dislocation creep. Infrared spectral analysis was carried out using a Nicolet micro-FTIR on mylonitic quartz ribbons, pegmatitic quartz and gneissic quartz. A small aperture size (56 μm by 50 μm) for the IR beam allowed optically clear regions of the quartz grains to be analyzed without any contribution from grain boundaries. The smallest dimension of the quartz ribbons is 0.3 mm, whereas the pegmatitic quartz has a grain size of 3 to 5 cm. Results show mylonitic quartz ribbons contain the most water (320 H:10 6 Si average, range of 50 to 1120 H:10 6 Si); pegmatite quartz contains much less water (30 H:10 6 Si average, range of 20-40 H:10 6 Si) and the gneissic quartz contained an intermediate amount (200 H:10 6 Si average, range of 20 to 870 H:10 6 Si). These data indicate that water was preferentially incorporated into the deformed quartz ribbons.

  7. Kinetics of carbothermal reduction of quartz under vacuum.

    NASA Technical Reports Server (NTRS)

    Khalafalla, S. E.; Haas, L. A.

    1972-01-01

    Study of the kinetics of carbothermal reduction of quartz in a batch reactor between 0.25 torr and 1 microtorr. The effects of temperature, CO partial pressure, SiO2 phase transformation, and alkali and alkaline-earth oxide additives on the rate of reaction are reported. The results are consistent with a model based on a transitory phase intermediate.

  8. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C.; Morgan, Michael J.

    1986-02-04

    A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

  9. Biochemical evolution. I. Polymerization on internal, organophilic silica surfaces of dealuminated zeolites and feldspars

    PubMed Central

    Smith, Joseph V.

    1998-01-01

    Catalysis at mineral surfaces might generate replicating biopolymers from simple chemicals supplied by meteorites, volcanic gases, and photochemical gas reactions. Many ideas are implausible in detail because the proposed mineral surfaces strongly prefer water and other ionic species to organic ones. The molecular sieve silicalite (Union Carbide; = Al-free Mobil ZSM-5 zeolite) has a three-dimensional, 10-ring channel system whose electrically neutral Si-O surface strongly adsorbs organic species over water. Three -O-Si tetrahedral bonds lie in the surface, and the fourth Si-O points inwards. In contrast, the outward Si-OH of simple quartz and feldspar crystals generates their ionic organophobicity. The ZSM-5-type zeolite mutinaite occurs in Antarctica with boggsite and tschernichite (Al-analog of Mobil Beta). Archean mutinaite might have become de-aluminated toward silicalite during hot/cold/wet/dry cycles. Catalytic activity of silicalite increases linearly with Al-OH substitution for Si, and Al atoms tend to avoid each other. Adjacent organophilic and catalytic Al-OH regions in nanometer channels might have scavenged organic species for catalytic assembly into specific polymers protected from prompt photochemical destruction. Polymer migration along weathered silicic surfaces of micrometer-wide channels of feldspars might have led to assembly of replicating catalytic biomolecules and perhaps primitive cellular organisms. Silica-rich volcanic glasses should have been abundant on the early Earth, ready for crystallization into zeolites and feldspars, as in present continental basins. Abundant chert from weakly metamorphosed Archaean rocks might retain microscopic clues to the proposed mineral adsorbent/catalysts. Other framework silicas are possible, including ones with laevo/dextro one-dimensional channels. Organic molecules, transition-metal ions, and P occur inside modern feldspars. PMID:9520372

  10. CO2 sequestration in feldspar-rich sandstone: Coupled evolution of fluid chemistry, mineral reaction rates, and hydrogeochemical properties

    NASA Astrophysics Data System (ADS)

    Tutolo, Benjamin M.; Luhmann, Andrew J.; Kong, Xiang-Zhao; Saar, Martin O.; Seyfried, William E.

    2015-07-01

    transport modeling experiments to explore processes occurring during the flow-through experiments, we have found that the overall progress of feldspar hydrolysis is negligibly affected by quartz dissolution, but significantly impacted by the rates of secondary mineral precipitation and their effect on feldspar saturation state. The observations produced here are critical to the development of models of CCUS operations, yet more work, particularly in the quantification of coupled dissolution and precipitation processes, will be required in order to produce models that can accurately predict the behavior of these systems.

  11. Milk-alkali syndrome

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000332.htm Milk-alkali syndrome To use the sharing features on this page, please enable JavaScript. Milk-alkali syndrome is a condition in which there ...

  12. Magnetic Properties Of Feldspars And Other Rock-forming Minerals: Evaluation Of Their Potential As Paleointensity Recorders

    NASA Astrophysics Data System (ADS)

    Cottrell, R. D.; Smirnov, A. V.; Tarduno, J. A.

    The continued development of highly sensitive SQUID magnetometers has opened the way for paleomagnetic and paleointensity studies of individual rock forming miner- als. The motivation for these studies is the desire to avoid contamination of magnetic data related to secondary minerals that commonly form in the ground mass of igneous rocks on geologic timescales or during laboratory experiments. As part of a survey of various mineral phases we have examined magnetic hysteresis data of olivine, py- roxene and feldspar separated from mafic lavas flows, quartz separated from tuffs and zircon separated from granites. Our studies of optically clear plagioclase feldspar have shown them to have several properties favorable for paleointensity investigations. Hys- teresis properties indicate that the domain state of magnetic inclusions in the feldspar crystals is single or pseudosingle domain while that of the groundmass is pseudosingle to multidomain. High resolution SEM and TEM analyses indicate that the magnetic inclusions are equant to slightly elongated and are 50 to 350 nm in size. Low tempera- ture data and magnetic unblocking temperatures indicate that the overall composition of the inclusions is similar to that of the bulk volcanic rocks from which they were separated. These properties, together with the relatively rapid cooling characteristics of lavas, suggest that Thellier analyses of plagioclase feldspars will continue to yield important paleointensity data. The potential of other mineral phases for paleomagnetic and paleointensity studies will be discussed.

  13. Timescales of quartz crystallization and the longevity of the Bishop giant magma body.

    PubMed

    Gualda, Guilherme A R; Pamukcu, Ayla S; Ghiorso, Mark S; Anderson, Alfred T; Sutton, Stephen R; Rivers, Mark L

    2012-01-01

    Supereruptions violently transfer huge amounts (100 s-1000 s km(3)) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ~760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies. PMID:22666359

  14. Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body

    SciTech Connect

    Gualda, Guilherme A.R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Jr. , Alfred T.; Sutton, Stephen R.; Rivers, Mark L.

    2013-04-08

    Supereruptions violently transfer huge amounts (100 s-1000 s km{sup 3}) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted {approx}760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

  15. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    USGS Publications Warehouse

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the

  16. Brittle grain size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, Gustavo; Menegon, Luca; Archanjo, Carlos

    2016-04-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse (> 50 μm) grained feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (< 15 μm in size) localized in C' shear bands. Detailed microstructural observations and EBSD analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (˜ 1-2 mm) monomineralic bands or as thin ribbons dispersed in the feldspathic mixture. The microstructure and c-axis crystallographic preferred orientation are similar in the thick monomineralic band and in the thin ribbons, and suggest dominant subgrain rotation recrystallization and activity of prism and rhomb slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the monomineralic veins to the thin ribbons embedded in the feldspathic C' bands (14 μm vs 5 μm, respectively).The fine-grained feldspar mixture has a weak crystallographic preferred orientation interpreted as the result of oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Assuming that the C' shear bands deformed under constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate one order of magnitude faster than the monophase quartz ribbons. Overall, our dataset indicates that feldspar underwent a brittle-viscous transition while quartz was deforming via crystalline plasticity. The resulting rock microstructure consists of a two-phase rheological mixture (fine-grained feldspars and recrystallized quartz) in which the feldspathic material

  17. Brittle grain size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, G.; Menegon, L.; Archanjo, C. J.

    2015-10-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse (> 50 μm) grained feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (~ < 15 μm in size) localized in C' shear bands. Detailed microstructural observations and EBSD analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (~ 1-2 mm) monomineralic bands or as thin ribbons dispersed in the feldspathic mixture. The microstructure and c axis crystallographic preferred orientation are similar in the thick monomineralic band and in the thin ribbons, and suggest dominant subgrain rotation recrystallization and activity of prism ⟨a⟩ and rhomb ⟨a⟩ slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the transposed veins to the thin ribbons embedded in the feldspathic C' bands (14 μm vs. 5 μm, respectively). The fine-grained feldspar mixture has a weak crystallographic preferred orientation interpreted as the result of oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Assuming that the C' shear bands deformed under constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate one order of magnitude faster than the monophase quartz ribbons. Overall, our dataset indicates that feldspar underwent a brittle-viscous transition while quartz was deforming via crystal plasticity. The resulting rock microstructure consists of a two-phase rheological mixture (fine-grained feldspars and recrystallized quartz) in which the polyphase

  18. The evolution and significance of microfracturing within feldspars in low-grade granitic mylonites: A case study from the Eastern Ghats Mobile Belt, India

    NASA Astrophysics Data System (ADS)

    Sinha, Suspa; Alsop, G. Ian; Biswal, T. K.

    2010-10-01

    Patterns of microfracturing are investigated in plagioclase and K-feldspar porphyroclasts formed within granitic mylonites along the boundary of the Eastern Ghats Mobile Belt, India. The mineral assemblage comprising quartz, feldspar, biotite and hornblende suggests lower greenschist facies conditions during mylonitisation, with the contrasting ductile behaviour of quartz and brittle fracturing of feldspars restricting the temperature range during deformation to 300-350 °C. Microfracturing of feldspars takes place by concentration of pure shear within the feldspar-rich layers. This may reflect strain partitioning into dominantly pure and simple shear due to the competency contrasts between the two major constituent minerals (quartz and feldspar). The microfractures occur in conjugates (here designated T 1 and T 2) with T 1 inclined in the same direction as the S-fabric and showing an antithetic sense to the NW verging shear, while T 2 is inclined in an opposite sense to the S-fabric and displays synthetic shear. The direction of maximum compression occurs at high angles to the C-fabric, and the T 1 and T 2 fractures are the result of pure shear localized into brittle layers within the mylonite. With progressive shear, the fractures along with their host feldspar grains are rotated. Theoretical graphs are plotted between bulk shear ( γ) and the angle of initiation ( α) of T 1 and T 2 with respect to C-planes, for fractures hosted in a circular or elliptical objects. The kinematics of these fractures are also analyzed with regard to variations in shear strain and sense of shear along them. The sense of shear may vary or remain stable within fractures, depending on their initial angle of inclination with respect to the C-fabric. As T 1 is inclined at low angles to the XY plane and in the same direction as the S-fabric, it undergoes maximum shear strain compared to T 2 and may even exceed the bulk shear. This facilitates breakdown of feldspar porphyroclasts during

  19. Feldspar microtextures and multistage thermal history of syenites from the Coldwell Complex, Ontario

    NASA Astrophysics Data System (ADS)

    Waldron, Kim A.; Parsons, Ian

    1992-06-01

    Optical and TEM (transmission electron microscopy) observations of perthites from augite syenites in the Coldwell Complex (Ontario) reveal a complex set of microtextures that outline a multistage thermal history. Regular microtextures (linear or braid texture, straincontrolled, coherent intergrowths) show a progressive evolution from the margin of the intrusion inwards with lamellar spacings in the range 40 100 nm. The textures evolve in a manner similar to those for the Klokken intrusion and reflect differences in cooling rates and bulk composition. Superimposed upon the regular microtexture are 10 μm scale compositional fluctuations which we call “ripples”. The boundary relationships and bulk composition of ripples, which are themselves Ab-rich and Or-rich linear coherent cryptoperthites, suggest that they formed by coarsening during a phase of high-temperature (˜530°C) fluid-feldspar interaction. This was followed by a return to coherent exsolution in which fluid was not involved. Coarse, irregular, patch microperthite cross-cuts all other microtextures. These final “deuteric” intergrowths are believed to result from a further low-temperature (< 380° C) fluid-feldspar interaction and are associated with subgrain formation and the presence of micropores. The outermost syenite sample, against a gabbro ring structure, has distinctive, modified microtextures, indicating that the gabbro is, at least in part, a later intrusion. Our findings show that TEM work on alkali feldspar microtextures can identify discrete thermal events in the cooling history of igneous plutons and illustrates the potential of such microtextures for establishing the relative ages of intrusive rocks.

  20. Lunar granites with unique ternary feldspars

    NASA Technical Reports Server (NTRS)

    Ryder, G.; Stoeser, D. B.; Marvin, U. B.; Bower, J. F.

    1975-01-01

    An unusually high concentration of granitic fragments, with textures ranging from holocrystalline to glassy, occurs throughout Boulder 1, a complex breccia of highland rocks from Apollo 17, Station 2. Among the minerals included in the granites are enigmatic K-Ca-rich feldspars that fall in the forbidden region of the ternary diagram. The great variability in chemistry and texture is probably the result of impact degradation and melting of a granitic source-rock. Studies of the breccia matrix suggest that this original granitic source-rock may have contained more pyroxenes and phosphates than most of the present clasts contain. Petrographic observations on Apollo 15 KREEP basalts indicate that granitic liquids may be produced by differentiation without immiscibility, and the association of the granites with KREEP-rich fragments in the boulder suggests that the granites represent a residual liquid from the plutonic fractional crystallization of a KREEP-rich magma. Boulder 1 is unique among Apollo 17 samples in its silica-KREEP-rich composition. We conclude that the boulder represents a source-rock unlike the bedrock of South Massif.

  1. Fractionation of Stable Si Isotopes During in-situ Dissolution of Feldspars and Formation of Secondary Clay Minerals

    NASA Astrophysics Data System (ADS)

    Georg, R. B.; Reynolds, B. C.; Halliday, A. N.; Zhu, C.

    2005-12-01

    It has been proposed that weathering of igneous silicate minerals may fractionate Si isotopes (Douthitt 1982, de la Rocha et al. 2000). This is supported by the observation that clays yield δ30Si compositions between +0.5‰ and -2.5‰ compared to the igneous range for δ30Si between +0.1‰ and -1‰ respectively (Douthitt 1982). The difference may relate to a discrimination against heavier Si isotopes during clay mineral formation. However, no study has yet shown a direct Si isotope fractionation between coexisting primary igneous and secondary clay mineral phases. We have measured the stable Si isotope fractionation during in-situ feldspar dissolution and formation of secondary clay minerals in the Navajo Sandstone, Black Mesa, Arizona. The Jurassic Navajo Sandstone is composed of about 94% quartz and 2-4% K-feldspar. The K-feldspar grains are covered with kaolinite, and both quartz and feldspars are covered with a mantle of smectite coating. Petrographic studies demonstrate that the clay minerals formed in situ as alteration products of feldspar, and the smectite is of a low-temperature variety (Zhu, 2005). Therefore, the Si isotope fractionation at low temperature (15-35°C) can be evaluated - something that is difficult to replicate in the laboratory. For the Si isotope analyses we used 20-30 mg of 5 separated clay samples, and 0.36 mg of hand picked feldspars. The silicates were fused with an alkaline flux and dissolved in a weak HCl acid. The dissolved Si was then separated by ion-exchange chromatography. The relative Si isotope compositions were measured using a high-resolution MC-ICP-MS (The Nu1700 at ETH Zurich) and are reported in δ notation relative to the international Si standard NBS 28. The bulk rock and separated feldspar fraction have Si isotope compositions are -0.09 ± 0.03‰ and -0.15 ±0.03 ‰ (±2σSEM) δ30Si, respectively. The clay samples have δ30Si values of -0.24 ±0.05‰, -0.16 ±0.03‰, -0.30 ±0.03‰, -0.42 ±0.03‰ and -0

  2. Distribution and textures of K-feldspar grains in the George Ashley Block layered-aplite pegmatite intrusive

    NASA Astrophysics Data System (ADS)

    Kleck, W. D.

    2013-12-01

    Both Johns & Tuttle (1963) and London (2008) note that the distribution of potassium is neither uniform nor symmetrical in some pegmatite bodies. A detailed chemical and mineral analysis of the George Ashley Block (Kleck & Foord 1999) shows that the distribution of K-feldspar over the entire body is generally uniform, but not symmetrical. The amounts of quartz, plagioclase, muscovite, and garnet are neither uniform nor symmetrical. It is noted that layered-aplite, pegmatite intrusives (terminology of Jahns & Tuttle 1963) are intruded horizontally, and it is suggested that these are the pegmatite bodies which have this non-uniform distribution of minerals. These types of pegmatite bodies are distinctly different from other pegmatite bodies in several ways. The core zone in these bodies is not centrally located and typically divides these bodies into a pegmatitic top and an aplitic bottom; the top and bottom appear to be contemporaneous. The features and content of the border- and core-zones are not included in this discussion. The texture of the K-feldspar in the top of these bodies is generally pegmatitic; some of the K-feldspar grains may exist as ultra-large grains which have a teardrop shape or minor-crystal surfaces. In the bottom of these bodies, the K-feldspar is commonly rounded grains approximately 1 mm in diameter; rarely, some K-feldspar grains here are centimeter-grained with crystal surfaces indicating growth. In the George Ashley Block, the concentration and distribution of K-feldspar is inversely symmetrical in the top vs. bottom. In the top it increases toward the core zone; K-feldspar--20 increasing to 60 vol% (all values one significant figure) and K2O--3 increasing to 8 wt%. In the bottom it decreases toward the core zone; K-feldspar--40 decreasing to 0 vol% and K2O--4 decreasing to 0 wt%. The two trends are approximately parallel and the total amounts are approximately constant. The suggested conditions and mechanisms (with the added condition of

  3. QUARTZ FIBER ELECTROSCOPES

    DOEpatents

    Henderson, R.P.

    1957-09-17

    An instrument carried unobtrusively about the person such as in a finger ring to indicate when that person has been exposed to an unusual radiation hazard is described. A metallized quartz fiber is electrically charged to indicate a full scale reading on an etched glass background. The quartz fiber and the scale may be viewed through a magnifying lens for ease of reading. Incident radiation will ionize gaseous particles in the sealed structure thereby allowing the charge to leak off the quartz fiber with its resulting movement across the scale proportionally indicating the radiation exposure.

  4. Effects of recrystallization and strain on Ti re-equilibration in quartz in a cooling pluton

    NASA Astrophysics Data System (ADS)

    Bestmann, Michel; Pennacchioni, Giorgio

    2014-05-01

    Since a couple of years the trace amount of Ti in quartz (Ti-in-quartz or TitaniQ) has been used to constrain the deformation temperature in quartzitic rocks. Independently of how precise the estimate of deformation temperature could be, a basic question still remains controversial of how effective is dynamic recrystallization to reset the Ti in quartz in mylonites. The study of a heterogeneous ductile shear zone developed during post-magmatic cooling of a titanite-bearing granodiorite allows the effect of strain and recrystallization on Ti re-equilibration in quartz to be assessed. The different strain facies show a heterogeneous distribution of Ti content (measured by SIMS) which correlates well with cathodoluminescence (CL) intensity. In the granodiorite protolith CL-bright Ti-rich (20-38 ppm) quartz shows CL-dark Ti-poor haloes (Ti as low as 6-8 ppm) surrounding euhedral titanite. Grain-scale heterogeneities include Ti depleted (CL-darker) grain boundaries (Ti 4-6 ppm). In the protomylonite quartz shows a variable degree of recrystallization associated with strain gradients along S-C foliations anastomosing around feldspar porphyroclasts. Original CL-dark haloes surrounding titanite were passively stretched into the foliation; away from these haloes recrystallized quartz appears mainly bright in CL and retained high Ti contents as in the protolith. Quartz-filled pressure shadows, appended to disrupted feldspar porphyroclasts, show dark CL indicative of very low Ti content (1-3 ppm). In the mylonites and ultramylonites quartz forms totally recrystallized layers that are dominantly dark in CL but show internally a "subtle" CL layering subparallel to foliation reflecting variations of Ti in the range of 3 to 12 ppm. EBSD analysis of quartz indicates that prism was the dominant crystallographic slip system, associated with subgrain formation and subgrain rotation recrystallization, at all stages of deformation. This indicates together with dynamic

  5. Crystallized alkali-silica gel in concrete from the late 1890s

    SciTech Connect

    Peterson, Karl . E-mail: cee@mtu.edu; Gress, David . E-mail: dlgress@unh.edu; Van Dam, Tom . E-mail: cee@mtu.edu; Sutter, Lawrence . E-mail: cee@mtu.edu

    2006-08-15

    The Elon Farnsworth Battery, a concrete structure completed in 1898, is in an advanced state of disrepair. To investigate the potential for rehabilitation, cores were extracted from the battery. Petrographic examination revealed abundant deposits of alkali silica reaction products in cracks associated with the quartz rich metasedimentary coarse aggregate. The products of the alkali silica reaction are variable in composition and morphology, including both amorphous and crystalline phases. The crystalline alkali silica reaction products are characterized by quantitative X-ray energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). The broad extent of the reactivity is likely due to elevated alkali levels in the cements used.

  6. Vacuum electrolysis of quartz

    DOEpatents

    King, James Claude

    1976-01-13

    The disclosure is directed to a method for processing quartz used in fabricating crystal resonators such that transient frequency change of resonators exposed to pulse irradiation is virtually eliminated. The method involves heating the crystal quartz in a hydrogen-free atmosphere while simultaneously applying an electric field in the Z-axis direction of the crystal. The electric field is maintained during the cool-down phase of the process.

  7. Alkali differentiation in LL-chondrites

    NASA Astrophysics Data System (ADS)

    Wlotzka, F.; Palme, H.; Spettel, B.; Wanke, H.; Fredriksson, K.; Noonan, A. F.

    1983-04-01

    The Kraehenberg and Bhola LL-group chondrites are heterogeneous agglomerates which contain a variety of lithic fragments and chondrules as well as crystal fragments. Both meteorites contain large, cm-sized fragments with high K enrichments. The K-rich inclusions are fragments of larger rock bodies which crystallized from melts of chondritic parent material that had previously been enriched in K and in heavier alkalies,while also being depleted in Na and metal. It is suggested that the K enrichment occurred as an exchange for Na in feldspars via a vapor phase, whose presence on the chondrite parent body (or bodies) is supported by the recent finding of fluid inclusions in chondritic silicates. Cooling rate considerations indicate that the K-rich rock units could not have been very large, implying that the K-rich materials were locally molten by, for example, impact.

  8. Quartz cementation mechanisms between adjacent sandstone and shale in Middle Cambrian, West Lithuania

    NASA Astrophysics Data System (ADS)

    Zhou, Lingli; Friis, Henrik

    2013-04-01

    Quartz is an important cementing material in siliciclastic sandstones that can reduce porosity and permeability severely. For efficiently predicting and extrapolating petrophysical properties such as porosity and permeability, the controls on the occurrence and the degree of quartz cementation need to be better understood. Because it is generally difficult to identify specific sources for quartz cement, many models attempting to explain quartz cementation conclude that external sources of silica are needed to explain the observed quantity of quartz cement, such as the mass transfer between sandstone and shale. Cambrian sandstones in Lithuania have abundant quartz cement which has significant effect on reservoir properties. The detrital quartz grains have been dissolved extensively along the shale-quartz contacts zones, making it a natural laboratory to study the influence of mass transfer between sandstone and shale to quartz cementation on petrophysical properties and reservoir quality. Our Cambrian shale samples in west Lithuania are mainly silty shale or siltstone (sample locations vary from 330 to 2090 m of burial depth). They are composed of quartz, clay and traces of feldspars, sericite, calcite, and pyrite. The clay minerals are mainly illite, with variable content of kaolinite and traces of chlorite. In the sandstone lamina, authigenic illite occurs as pore-filling cement which was composed of fibrous illite; pore-filling kaolinite is generally well crystallized and occurs as hexagonal plates arranged in booklets; quartz overgrowth are obvious in these sandstone laminas, especially in the contact zones between sandstone and shale. Dolomite and pyrite cementation are also present in some sandstone laminas but with few quartz overgrowth. Depositional facies and architecture played an important role in the precipitation of silica. Three different possible sources are distinguished for the quartz overgrowths in the intercalated sandstones: 1) Pressure

  9. Immersion freezing of aqueous suspensions of K-feldspar

    NASA Astrophysics Data System (ADS)

    Peckhaus, Andreas; Kiselev, Alexei; Leisner, Thomas

    2014-05-01

    Recent laboratory measurements showed an increased ice nucleation ability of Kalium-rich feldspar particles in the immersion freezing mode [1]. It was suggested that the proportion of K-feldspar in atmospherically relevant ice nuclei is related to their ice nucleation ability. The importance of K-feldspar is further supported by the field measurements, indicating that it can make a mass fraction of up to 24% in Asian and African mineral dusts [2]. In this contribution we present results of immersion freezing experiments with monodisperse droplets of aqueous suspensions of K-feldspar on a cold stage. We show that the ice nucleation activity strongly depends on i) the particle size distribution (in particular the ice nucleation properties of submicron feldspar particles) ii) the weight concentration of the particles in the aqueous suspension and thus on the total particle surface immersed into the droplets and iii) the age of the particles in an aqueous environment. Further a comparison of different K-feldspars is presented indicating that the origin and the processing methods have a significant impact on the IN activity. The mineralogical composition of feldspar samples is analyzed by means of Raman spectroscopy and a quantification of the particle surface is carried out with environmental scanning electron microscopy (ESEM). The results of freezing experiments are interpreted within the concept of ice nucleation active surface site (INAS) density, which allows a comparison with data obtained with different experimental methods (IN counters, expansion chambers, etc.) 1. Atkinson, J.D., et al., The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds. Nature, 2013. 498(7454): p. 355-358. 2. Nickovic, S., et al., Technical Note: High-resolution mineralogical database of dust-productive soils for atmospheric dust modeling. Atmospheric Chemistry and Physics, 2012. 12(2): p. 845-855.

  10. In situ 40K-40Ca ‘double-plus’ SIMS dating resolves Klokken feldspar 40K-40Ar paradox

    NASA Astrophysics Data System (ADS)

    Harrison, T. Mark; Heizler, Matthew T.; McKeegan, Kevin D.; Schmitt, Axel K.

    2010-11-01

    The 40K- 40Ca decay system has not been widely utilized as a geochronometer because quantification of radiogenic daughter is difficult except in old, extremely high K/Ca domains. Even these environments have not heretofore been exploited by ion microprobe analysis due to the very high mass resolving power (MRP) of 25,000 required to separate 40K + from 40Ca +. We introduce a method that utilizes doubly-charged K and Ca species which permits isotopic measurements to be made at relatively low MRP (~ 5000). We used this K-Ca 'double-plus' approach to address an enduring controversy in 40Ar/ 39Ar thermochronology revolving around exsolved alkali feldspars from the 1166 Ma Klokken syenite (southern Greenland). Ion microprobe 40K- 40Ca analysis of Klokken samples reveal both isochron and pseudoisochron behaviors that reflect episodic isotopic and chemical exchange of coarsely exsolved perthites and a near end-member K-feldspar until ≤ 719 Ma, and perhaps as late at ~ 400 Ma. Feldspar microtextures in the Klokken syenite evolved over a protracted interval by non-thermal processes (fluid-assisted recrystallization) and thus this sample makes a poor model from which to address the general validity of 40Ar/ 39Ar thermochronological methodologies.

  11. Investigation of Potassium Feldspar Reactivity in Wet Supercritical CO2 by In Situ Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, C.; Widener, C.; Schaef, T.; Loring, J.; McGrail, B. P.

    2014-12-01

    Capture and subsequent storage of CO2 in deep geologic reservoirs is progressively being considered as a viable approach to reduce anthropogenic greenhouse gas emissions. In the long term, injected CO2 may become permanently entrapped as silicate minerals react with CO2 enriched fluids to form stable carbonate minerals. Potassium feldspars are highly abundant in the earth's crust and are present in the caprocks and storage formations of many target reservoirs. While the dissolution kinetics and carbonation reactions of feldspars have been well studied in the aqueous phase, comparatively little work has focused on K-feldspar reactivity in the CO2-rich fluid. In this study, we used in situ infrared spectroscopy to investigate the carbonation reactions of natural microcline samples. Experiments were carried out at 50 °C and 91 bar by circulating dry or wet supercritical CO2 (scCO2) past a thin film of powdered sample. Water concentrations ranged from 0% to 125% relative to saturation, and transmission-mode absorbance spectra were recorded as a function of time for 48 hours. No discernible reaction was detected when the samples were exposed to anhydrous scCO2. However, in fully water-saturated scCO2, a thin film of liquid-like water was observed on the samples' surfaces, and up to 0.6% of the microcline was converted to a carbonate phase. Potassium carbonate is the most likely reaction product, but minor amounts of sodium carbonate and siderite may also have formed from minor sample impurities. The extent of reaction appears to be related to the thickness of the water film and is likely a consequence of the film's ability to solvate and transport ions in the vicinity of the mineral surface. Other features observed in the spectra correspond to microcline dissolution and precipitation of amorphous silica. Implications about the role of water in these reactions and the relative effectiveness of alkali feldspars for mineral trapping of CO2 will be discussed.

  12. Differential rates of feldspar weathering in granitic regoliths

    USGS Publications Warehouse

    White, A.F.; Bullen, T.D.; Schulz, M.S.; Blum, A.E.; Huntington, T.G.; Peters, N.E.

    2001-01-01

    Differential rates of plagioclase and K-feldspar weathering commonly observed in bedrock and soil environments are examined in terms of chemical kinetic and solubility controls and hydrologic permeability. For the Panola regolith, in the Georgia Piedmont Province of southeastern United States, petrographic observations, coupled with elemental balances and 87Sr/86Sr ratios, indicate that plagioclase is being converted to kaolinite at depths > 6 m in the granitic bedrock. K-feldspar remains pristine in the bedrock but subsequently weathers to kaolinite at the overlying saprolite. In contrast, both plagioclase and K-feldspar remain stable in granitic bedrocks elsewhere in Piedmont Province, such as Davis Run, Virginia, where feldspars weather concurrently in an overlying thick saprolite sequence. Kinetic rate constants, mineral surface areas, and secondary hydraulic conductivities are fitted to feldspar losses with depth in the Panola and Davis Run regoliths using a time-depth computer spreadsheet model. The primary hydraulic conductivities, describing the rates of meteoric water penetration into the pristine granites, are assumed to be equal to the propagation rates of weathering fronts, which, based on cosmogenic isotope dating, are 7 m/106 yr for the Panola regolith and 4 m/106 yr for the Davis Run regolith. Best fits in the calculations indicate that the kinetic rate constants for plagioclase in both regoliths are factors of two to three times faster than K-feldspar, which is in agreement with experimental findings. However, the range for plagioclase and K-feldspar rates (kr = 1.5 x 10-17 to 2.8 x 10-16 mol m-2 s-1) is three to four orders of magnitude lower than for that for experimental feldspar dissolution rates and are among the slowest yet recorded for natural feldspar weathering. Such slow rates are attributed to the relatively old geomorphic ages of the Panola and Davis Run regoliths, implying that mineral surface reactivity decreases significantly with

  13. Calorimetric investigation of the excess entropy of mixing in analbite-sanidine solid solutions: lack of evidence for Na,K short- range order and implications for two-feldspar thermometry.

    USGS Publications Warehouse

    Haselton, H.T., Jr.; Hovis, G.L.; Hemingway, B.S.; Robie, R.A.

    1983-01-01

    Heat capacities (5-380 K) have been measured by adiabatic calorimetry for five highly disordered alkali feldspars (Ab99Or1, Ab85Or15, Ab55Or45, Ab25Or75 and Ab1Or99). The thermodynamic and mineralogical implications of the results are discussed. The new data are also combined with recent data for plagioclases in order to derive a revised expression for the two-feldspar thermometer. T calculated from the revised expression tend to be higher than previous calculations.-J.A.Z.

  14. Optical contacting of quartz

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

  15. Quartz ball valve

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M. (Inventor)

    1980-01-01

    A ball valve particularly suited for use in the handling of highly corrosive fluids is described. It is characterized by a valve housing formed of communicating segments of quartz tubing, a pair of communicating sockets disposed in coaxial alignment with selected segments of tubing for establishing a pair of inlet ports communicating with a common outlet port, a ball formed of quartz material supported for displacement between the sockets and configured to be received alternately thereby, and a valve actuator including a rod attached to the ball for selectively displacing the ball relative to each of the sockets for controlling fluid flow through the inlet ports.

  16. Grain size reduction of feldspar and pyroxene, phase mixing, and strain localization in lower crustal shear zones (Lofoten, Norway)

    NASA Astrophysics Data System (ADS)

    Menegon, L.; Stunitz, H.; Nasipuri, P.; Svahnberg, H.; Heilbronner, R.

    2011-12-01

    High temperature shear zones are common in the magmatic suite of the granulite facies Lofoten basement of Norway, and typically consist of narrow structures (1 cm to 1 m in thickness) showing a mylonite-to ultramylonite transition from the shear zone boundary to the shear zone center. In this contribution we examine the deformation microstructures and synkinematic mineral assemblages of shear zones developed from a mangerite (=monzonite) protolith. The mineral assemblage in the host mangerite indicates anhydrous conditions (mesoperthite + clinopyroxene ± orthopyroxene), whereas the mineral assemblage in the shear zones consists of plagioclase + K-feldspar + quartz + hornblende + calcite + biotite ± clinopyroxene and indicates hydrated conditions. Hornblende-plagioclase geothermobarometry yields upper amphibolite- to granulite facies conditions during shearing (730-760° C, 0.55-0.8 GPa). The mylonite consists of two distinct compositional domains: a pyroxene-derived aggregate and a feldspar-derived aggregate. The pyroxene-derived aggregate consists of the products of the following breakdown reaction: clinopyroxene + plagioclase ± K-feldspar ± orthopyroxene + H2O + CO2 --> quartz + hornblende + calcite ± biotite. In the feldspar-derived aggregate fractured fragments of mesoperthite are surrounded by a bi-phase mixture of recrystallized plagioclase and K-feldspar. EBSD analysis indicates that the recrystallized grains originated as micro-fragments from fracturation, and recrystallization was compositionally-induced (e.g. An22 average composition of plagioclase in the mesoperthite, An14 in the recrystallized aggregate). Detailed grain size, grain shape and EBSD analysis indicate that diffusion creep was the dominant deformation mechanism in both aggregates. Spatial distribution of K-feldspar and plagioclase shows a well dispersed aggregate and may serve as a tool to characterize diffusion creep deformation in phase mixtures. In the ultramylonite the two

  17. Evidence for the compaction of feldspar-rich cumulates in the Pleasant Bay layered intrusion, coastal Maine

    SciTech Connect

    Horrigan, E.K. )

    1993-03-01

    The Pleasant Bay intrusion is roughly 12 km by 20 km. It consists of prominent rhythmic layers, up to 100 m thick, that grade from chilled gabbro on the base, to coarse-grained gabbroic, dioritic, or granitic rocks on the top. These layers were formed by multiple injections of basalt into a large chamber of silicic magma. The focus of this study is on one layer that is about 100 m thick, and is overlain by another basally chilled gabbroic layer at least 50 m thick. Silicic pipes and veins extend upward into the overlying gabbroic chill. The lower part of the layer has dominant calcic plagioclase, An60, augite, and olivine, with subordinate hornblende and biotite. The uppermost part has dominant sodic plagioclase, An20, and two pyroxenes with subordinate quartz, K-feldspar and hornblende. SiO[sub 2] and MgO vary from 49% and 5% at the base to 58% and 1% at the top, respectively. The top 7 m of this layer are characterized by variably deformed minerals. The deformation grades from bent biotite and plagioclase near the bottom to sutured plagioclase at the top. Pockets of undeformed quartz and K-feldspar in the uppermost rocks demonstrate that interstitial liquid was present during a after compaction. The pipes and veins probably represent trapped liquid and some crystals that were expelled into the overlying gabbroic chill.

  18. Galileo quartz clock

    NASA Technical Reports Server (NTRS)

    Block, M.; Meirs, M.; Rosenfeld, M.; Garriga, P. C.

    1979-01-01

    A quartz oscillator for use in the Galileo experiment (orbiter and Probe) for Jupiter mission 1982 are described. This oscillator has achieved significant performance breakthroughs by the use of an SC cut, double rotated, crystal in a titanium dewar flask. Some of the performance parameters as well as the design feature of the oscillator are presented.

  19. [The characteristics of microstructure and chemical compositions of K-feldspar, sphene and zircon with zoning structure].

    PubMed

    Liu, Chun-Hua; Wu, Cai-Lai; Lei, Min; Qin, Hai-Peng; Li, Ming-Ze

    2013-08-01

    K-feldspar, sphene and zircon in quartz monzonite from Shahewan, south Qinling, showing strong zoning structure. Characteristics of microstructure and chemical compositions of K-feldspar, sphene and zircon with zoning structure were investigated using advanced instruments of electron probe micro analyses equipped with wavelength dispersive spectrometer (EPM-WDS), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and laser ablation--inductively coupled plasma--mass spectrometry (LA-ICP-MS). Our study suggests that K+ could be substituted by small amounts of Na+, Ca2+, Ba2+, Fe2+ and Ce3+. Ca2+ in sphene could be replaced by V3+, Ce3+, Ba2+ and Ti4+ could be substituted by both Fe2+ and Al3+. Zircon contains trace elements like Fe, Th, U, Nb, Ta, Y, Hf, Yb and Pb. Concentration of Si, Al, K, Ca, Na, Mg and Ba in K-feldspar ranked from high to low, among which the contents of K and Na are negatively correlated, the lighter part of BSE images featuring K-feldspar is attributed to comparably higher Ba content, additionally, Si and K contents are elevated while Na content decreased rimward. Ca, Si, Ti, Ba, V, Ce, Al and Fe concentration listed downward, among which higher iron content corresponds to brighter portion of BSE images. Element concentration of zircon could be ranked from high to low as Zr, Si, Nd, Ce, Hf, U, Pb and Th, in which Hf and Zr exhibit negatively correlated. Zr concentration increased while Hf, U and Th concentration decreased from core to rim. PMID:24159884

  20. Petrology, composition, and age of intrusive rocks associated with the Quartz Hill molybdenite deposit, southeastern Alaska.

    USGS Publications Warehouse

    Hudson, T.; Smith, James G.; Elliott, R.L.

    1979-01-01

    A large porphyry molybdenum deposit (Quartz Hill deposit) was recently discovered in the heart of the Coast Range batholithic complex about 70 km E of Ketchikan, SE Alaska. Intrusive rocks associated with the mineral deposit form two composite epizonal to hypabyssal stocks and many dikes in country rocks. All observed metallization and alteration is within the Quartz Hill stock. Molybdenite forms fracture coatings and occurs in veins with quartz. Alteration is widespread and includes development of secondary quartz, pyrite, K-feldspar, biotite, white mica, chlorite, and zeolite. Field relations indicate that the stocks were emplaced after regional uplift and erosion of the Coast Range batholithic complex, and K-Ar data show that intrusion and alteration took place in late Oligocene time, about 27 to 30 Ma ago. Data from the Ketchikan quadrangle indicate that porphyry molybdenum metallization in the Coast Range batholithic complex is associated with regionally extensive but spotty, middle Tertiary or younger, felsic magmatism. -from Authors

  1. Time-resolved luminescence from quartz: An overview of contemporary developments and applications

    NASA Astrophysics Data System (ADS)

    Chithambo, M. L.; Ankjærgaard, C.; Pagonis, V.

    2016-01-01

    Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz-feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.

  2. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  3. Immersion Freezing of Potassium-feldspar and related Natural Samples

    NASA Astrophysics Data System (ADS)

    Zolles, Tobias; Burkart, Julia; Grothe, Hinrich

    2014-05-01

    Ice nucleation activities of mineral dust particles were investigated. The experiments were carried out using cryo-microscopy which is an oil-emulsion based method. The immersion freezing mode was addressed with this experimental setup. The studied samples were common inorganic atmospheric aerosols. Single minerals and natural samples were tested [1]. Mineral dust particles are active ice nuclei in the immersion freezing mode up to 256 K. Only recently potassium-feldspar has been identified as the by far most active ice nucleus followed by other silicates [2, 3]. Natural samples which contain more than 5% K-feldspar are also active. The activity of K-feldspar can be attributed to its surface structure and the presence of potassium ions in the surface. Ice nucleation on mineral dust particles takes place at certain nucleation sites. These sites are domains of molecular sites where water is stabilized in an ice-like structure. To form a good ice nucleation site, the site density of molecular sites needs to be high. More molecular sites are able to form larger domains on the surface, leading to better nucleation sites. This suggests further that the nucleation temperature of mineral dust particles scales with the surface area. The exact configuration of a molecular site is material specific and influenced by the local chemistry and structure of the dust particle surface. A favourable arrangement of the functional groups like surface hydroxyl and oxygen is proposed for the K-feldspar. Potassium ions seem to have a positive or neutral effect on the ice nucleation property of a silicate surface while cations with a higher charge density like calcium and sodium have a negative influence. K-feldspar is abundant in the environment and actually is the most important dust ice nucleus in the atmosphere. The nucleation temperatures of the K-feldspar particles are sufficient to enable further meteorological glaciation processes in high altitude clouds. References [1] Zolles, T

  4. The generation of HCl in the system NaCl-KCl-H{sub 2}O-quartz at 600{degrees}C: Implications regarding HCl in natural systems at lower temperatures

    SciTech Connect

    Fournier, Robert O.; Thompson, J. Michael

    1993-01-28

    In experiments at 600°C in the system NaCI-KCI-H2O, within the analytical uncertainty, stoichiometric quantities of Cl and total alkali metals (Na+K) appear to dissolve in steam coexisting with chloride-rich brine at high pressures in the absence of solid salt. In contrast, at lower pressures, where steam coexists with precipitated salts, significant excess chloride as associated hydrogen chloride (HCI°) dissolves in steam. The HCI° appears to be generated by the reaction of solid NaCl(s) (halite) with steam, producing solid NaOH(s) that diffuses into halite, forming a solid solution. Where HCI° is present highly associated NaOH° as well as associated NaCI° appear to dissolve in steam, and the solubility of each is increased as the mole fraction of NaOH(s) in halite increases. In our quasi-static experiments, compared to dynamic flow-through experiments of others, higher initial ratios of H2O/NaCI have resulted in higher mole fractions of NaOH(s) in solid solution in halite and, accordingly, higher solubilities of NaCI" and NaOH" dissolved in steam. Addition of quartz to the system NaCI-KCI-H2O results in the formation of sodium disilicate by reaction of silica with NaOH(s) and an order of magnitude increase in the concentration of HCl° dissolved in steam. In natural hydrothermal systems at lower temperatures where brine or brine plus steam are present in the absence of precipitated salt, the pH of the brine is controlled mainly by base exchange reactions involving a variety of silicates that fix Na+/H+ and K+/H+ activity ratios. Where feldspars are present pH values generally are near neutral. Where mica, but no feldspar is present pH values may become only moderately acid. High acidity in salt-absent brine systems occurs only where all feldspars and mica have been altered to other minerals (generally pyrophyllite/ kaolinite or alunite). The situation changes significantly when

  5. Heat transfer in quartz, orthoclase, and sanidine at elevated temperature

    NASA Astrophysics Data System (ADS)

    Höfer, M.; Schilling, F.

    The thermal diffusivity of quartz, orthoclase, and sanidine was measured in different directions by a transient method, to determine the second-rank tensor of thermal transport properties as a function of temperature up to 800 °C. Thermal diffusivity of phonons is described as D=1/3 v l, where v is the phonon velocity and l the mean free path length of phonons. In quartz the thermal diffusivity at room temperature is 3.60 mm2 s-1 in [1 0 0] and 7.00 mm2 s-1 in [0 0 1] direction. A 1/T dependency of thermal diffusivity is observed for both directions up to 550 °C with a pronounced anisotropy (A=62% A=(Dmax - Dmin)/Daverage), which decreases with increasing temperature. Close to the α-β-phase transition, we observed a minimum in thermal diffusivity and a negligible anisotropy. Up to 573 °C the maximam of thermal diffusivity, average phonon velocity, and mean free path length are observed in [0 0 1] direction. However, above the temperature of phase transition the maximum values of the properties are observed in [1 0 0] direction. The observed behavior is explained by a model which interrelates velocity and mean free path length of phonons. A further contribution to the thermal diffusivity behavior is related to the higher symmetry of β-quartz, resulting in a reduced phonon-phonon-scattering probability. At ambient temperature, orthoclase and sanidine show similar values of thermal diffusivities ( 1 mm2 s-1) and a temperature-independent anisotropy behavior between 22 and 350 °C of 30%. For both feldspars a small 1/T temperature dependence of thermal diffusivity up to 350 °C is observed. The transparent sanidine in gemstone quality shows a strong increase in thermal diffusivity above 350 °C proportional to T 3. The contribution of the radiative heat-transfer mechanism leads to values more than two times higher in sanidine than in a milky-cloudy orthoclase at 800 °C. For the feldspars the mean free path length of phonons shows a small temperature dependence

  6. Quartz crystal growth

    DOEpatents

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  7. Colorado quartz: occurrence and discovery

    USGS Publications Warehouse

    Kile, D.E.; Modreski, P.J.; Kile, D.L.

    1991-01-01

    The many varieties and associations of quartz found throughout the state rank it as one of the premier worldwide localities for that species. This paper briefly outlines the historical importance of the mineral, the mining history and the geological setting before discussing the varieties of quartz present, its crystallography and the geological enviroments in which it is found. The latter include volcanic rocks and near surface igneous rocks; pegmatites; metamorphic and plutonic rocks; hydrothermal veins; skarns and sedimentary deposits. Details of the localities and mode of occurrence of smoky quartz, amethyst, milky quartz, rock crystal, rose quartz, citrine, agate and jasper are then given. -S.J.Stone

  8. Thermoluminescence signal in K-feldspar grains: Revisited.

    PubMed

    Gong, Gelian; Sun, Weidong; Xu, Hongyun

    2015-11-01

    Recent work has shown that infrared stimulated luminescence (IRSL) signals in sedimentary coarse-grain K-feldspars are derived mainly from high temperature thermoluminescence (TL) peaks around 400°C, and the fading components of the IRSL signal can be preferentially removed by prior IR stimulation at relatively low temperature. Considering the complexity of TL signal for very old samples, we may choose non-fading components from K-feldspar TL signals using the combination of optical and thermal activation methods. This paper examines a protocol of post-IR isothermal TL (i.e. pIRITL) signal for sedimentary coarse-grain K-feldspars, which results from isothermal TL measurements following elevated temperature IR bleaching. We show that a sum of two exponential decay functions can fit well to the pIRITL decay curves, and both the holding temperature for isothermal TL measurements and the prior elevated temperature IR bleaching can affect greatly the fast components of pIRITL signal. The dose response ranges of pIRITL signal are wider than those of post-IR IRSL signals, but the relative high residual pIRITL signal means that it is not appropriate for dating young samples. It is expected that one isothermal TL signal for K-feldspar measured at ~400°C following IR bleaching at 290°C (i.e. pIRITL400) is useful for dating very old samples. PMID:26257084

  9. The compression pathway of quartz

    SciTech Connect

    Thompson, Richard M.; Downs, Robert T.; Dera, Przemyslaw

    2011-11-07

    The structure of quartz over the temperature domain (298 K, 1078 K) and pressure domain (0 GPa, 20.25 GPa) is compared to the following three hypothetical quartz crystals: (1) Ideal {alpha}-quartz with perfectly regular tetrahedra and the same volume and Si-O-Si angle as its observed equivalent (ideal {beta}-quartz has Si-O-Si angle fixed at 155.6{sup o}). (2) Model {alpha}-quartz with the same Si-O-Si angle and cell parameters as its observed equivalent, derived from ideal by altering the axial ratio. (3) BCC quartz with a perfectly body-centered cubic arrangement of oxygen anions and the same volume as its observed equivalent. Comparison of experimental data recorded in the literature for quartz with these hypothetical crystal structures shows that quartz becomes more ideal as temperature increases, more BCC as pressure increases, and that model quartz is a very good representation of observed quartz under all conditions. This is consistent with the hypothesis that quartz compresses through Si-O-Si angle-bending, which is resisted by anion-anion repulsion resulting in increasing distortion of the c/a axial ratio from ideal as temperature decreases and/or pressure increases.

  10. Characterization of unswept and swept quartz crystals for space applications

    NASA Astrophysics Data System (ADS)

    Lefèvre, J.; Devautour-Vinot, S.; Cambon, O.; Boy, J.-J.; Guibert, P.; Chapoulie, R.; Inguimbert, C.; Picchedda, D.; Largeteau, A.; Demazeau, G.; Cibiel, G.

    2009-06-01

    Unswept and vacuum-swept synthetic quartz crystals were investigated in order to determine the mechanisms responsible for the radiation sensitivity of this material. Results were obtained by means of infrared (IR) spectroscopy, dielectric relaxation spectroscopy (DRS), and thermoluminescence (TL). First, the effect of vacuum sweeping was clearly demonstrated in IR absorption by a significant decrease in the amount of hydroxyl ions and in DRS by the disappearance of the dielectric loss peak arising from the relaxation of alkali ions. Second, it was shown that swept quartz is less sensitive to irradiation than the unswept crystal. A sharp decrease in the TL sensitivity of the electrolyzed material was observed in the energy range corresponding to the recombination of alkaline-electronic defects. DRS results indicated that the dielectric signal is shifted toward a lower energy range for both types of crystals, suggesting that the irradiation greatly facilitates the relaxation of alkaline species by creating low energy hosting sites. However, this shift is drastically less pronounced in the swept quartz because relaxing species are more stable in this material. Third, a correlation was established in TL between trapped charge carriers at point defects in quartz and the frequency variation in quartz oscillators, which is a very promising result for space applications.

  11. Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body

    PubMed Central

    Gualda, Guilherme A. R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Alfred T.; Sutton, Stephen R.; Rivers, Mark L.

    2012-01-01

    Supereruptions violently transfer huge amounts (100 s–1000 s km3) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ∼760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500–3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies. PMID:22666359

  12. Igneous origin of K-feldspar Megacrysts in Granitic Rocks of the Sierra Nevada Batholith

    NASA Astrophysics Data System (ADS)

    Moore, J. G.; Sisson, T. W.

    2007-12-01

    Study of the four principal K-feldspar megacrystic granitic plutons and related porphyrys in the Sierra Nevada composite batholith indicates that the included megacrysts are phenocrysts that grew in contact with granitic melt in long-lasting magma chambers. These 89-83 Ma plutons or intrusions are the youngest in the range, and represent the culminating magmatic phase of the batholith. They are the: Granodiorite of Topaz Lake; Cathedral Peak Granodiorite, Mono Creek Granite, Whitney Granodiorite, Johnson Granite Porphyry, and Golden Bear Dike. The zoned megacrysts in each of these igneous bodies attain 4-10 cm in length and all display oscillatory zoning with each zone beginning with a sharp increase followed by a gradual decrease in the concentration of BaO - commonly from 3 to 1 weight percent. Some of the more pronounced zones overlie resorption and channeling features on the underlying zone. Trains of small mineral inclusions (plagioclase, biotite, hornblende, quartz, sphene, and accessory minerals) are parallel to the BaO-delineated zones. The long axes of the inclusions are preferentially aligned parallel to the zone boundaries and inclusions are sorted by size from zone to zone. The growth temperature of sphene included in K-feldspar megacrysts is estimated by use of a Zr-in-sphene geothermometer. The sphene grains all yield igneous temperatures, mainly 735 - 760 °C. Sphene grains in the granodiorite host marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus range. The zoning of the megacrysts, their presence in quenched porphry dikes, and the limited range and igneous values of growth temperatures of sphene inclusions within them, support the interpretation that the megacrysts formed as igneous sanidine phenocrysts, and that intrusion temperatures varied by only small amounts while the megacrysts grew. Each Ba- enriched zone was apparently formed by a repeated surge of new, hot melt injected into the large

  13. Potassium Feldspar Megacrysts in Granites: Passive Markers of Magma Dynamics or Products of Textural Coarsening?

    NASA Astrophysics Data System (ADS)

    Johnson, B. R.; Glazner, A. F.; Coleman, D. S.

    2006-12-01

    Megacrysts of potassium feldspar (K-spar) in granitic rocks are commonly interpreted as early-crystallizing phases whose textural relationships record flow, settling, and diapirism within evolving magma chambers. However, experimental studies on granitic magmas show that K-spar does not begin to nucleate until the system is at least 30% crystalline, and that much of the final crystallization history records co-crystallization of K-spar, quartz, and sodic plagioclase. These data require that the megacrysts cannot have reached large sizes until the magma was largely crystallized and incapable of flow. We have made chemical and textural observations of K-spar megacrysts from the Tuolumne Intrusive Suite (TIS), California. Cathodoluminescence images show sawtooth oscillatory zoning in K-spars, albite-rich rims on plagioclase, reaction zones at boundaries between plagioclase and K-spar, and almost no perthite. Electron microprobe analyses of the sawtooth zones reveal a sharp outward increase in Ba concentration at each zone boundary. Plagioclase core compositions follow whole-rock compositions, becoming increasingly albitic toward the center of the TIS, but K-spar in all units is highly potassic (Or80-95). A three-feldspar assemblage (An15-35, An1-7, and Or80-95) occurs in several megacrystic samples. Stained rock slabs reveal tentacles of interstitial K-spar radiating from megacryst edges far into the adjacent matrix, and a deficit of smaller K-spar crystals in megacrystic units. K-spar size measurements across the contacts of the TIS from the 10 largest crystals within a 1 m2 area show a steady increase in the average megacryst area from 0.2 to 30 cm2. In contrast, bulk rock K2O and K-spar mode (vol%) are constant across this same transect (at 3.7± 0.5 wt% and 22± 5 vol% respectively). Extreme feldspar compositions, phase equilibria, and textural observations argue for late development of K- spar megacrysts during the prolonged and probably cyclic cooling history of

  14. (Energy related studies utilizing K-feldspar thermochronology)

    SciTech Connect

    Not Available

    1992-01-01

    In our second year of current funding cycle, we have investigated the Ar diffusion properties and microstructures of K-feldspars and the application of domain theory to natural K-feldspars. We completed a combined TEM and argon diffusion study of the effect of laboratory heat treatment on the microstructure and kinetic properties of K-feldspar. We conclude in companion papers that, with one minor exception, no observable change in the diffusion behavior occurs during laboratory extraction procedures until significant fusion occurs at about 1100{degrees}C. The effect that is observed involves a correlation between the homogenization of cryptoperthite lamelle and the apparent increase in retentivity of about 5% of the argon in the K-feldspar under study. We can explain this effect of both as an artifact of the experiment or the loss of a diffusion boundary. Experiments are being considered to resolve this question. Refinements have been made to our experimental protocol that appears that greatly enhance the retrieval of multi-activation energies from K-feldspars. We have applied the multi-domain model to a variety of natural environments (Valles Caldera, Red River fault, Appalachian basin) with some surprising results. Detailed {sup 40}Ar/{sup 39} Ar coverage of the Red River shear zone, thought to be responsible for the accommodation of a significant fraction of the Indo-Asian convergence, strongly suggests that our technique can precisely date both the termination of ductile strike-slip motion and the initiation of normal faulting. Work has continued on improving our numerical codes for calculating thermal histories and the development of computer based graphing tools has significantly increased our productivity.

  15. Energy related studies utilizing K-feldspar thermochronology

    NASA Astrophysics Data System (ADS)

    In our second year of funding, we investigated the Ar diffusion properties and microstructures of K-feldspars and the application of domain theory to natural K-feldspars. We completed a combined TEM and argon diffusion study of the effect of laboratory heat treatment on the microstructure and kinetic properties of K-feldspar. We conclude in companion papers that, with one minor exception, no observable change in the diffusion behavior occurs during laboratory extraction procedures until significant fusion occurs at about 1100 C. The effect that is observed involves a correlation between the homogenization of cryptoperthite lamelle and the apparent increase in retentivity of about 5 percent of the argon in the K-feldspar under study. We can explain this effect of both as an artifact of the experiment or the loss of a diffusion boundary. Experiments are being considered to resolve this question. Refinements have been made to our experimental protocol that appear to enhance the retrieval of multi-activation energies from K-feldspars. We have applied the multi-domain model to a variety of natural environments (Valles Caldera, Red River fault, Appalachian basin) with some surprising results. Detailed Ar-40/Ar-39 coverage of the Red River shear zone, thought to be responsible for the accommodation of a significant fraction of the Indo-Asian convergence, strongly suggests that our technique can precisely date both the termination of ductile strike-slip motion and the initiation of normal faulting. Work has continued on improving our numerical codes for calculating thermal histories and the development of computer based graphing tools has significantly increased our productivity.

  16. Apparatus enables accurate determination of alkali oxides in alkali metals

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.; Gahn, R. F.; Graab, J. W.; Maple, W. E.; Rosenblum, L.

    1966-01-01

    Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure.

  17. Alkali-calcic and alkaline post-orogenic (PO) granite magmatism: petrologic constraints and geodynamic settings

    NASA Astrophysics Data System (ADS)

    Bonin, Bernard; Azzouni-Sekkal, Abla; Bussy, François; Ferrag, Sandrine

    1998-12-01

    The end of an orogenic Wilson cycle corresponds to amalgamation of terranes into a Pangaea and is marked by widespread magmatism dominated by granitoids. The post-collision event starts with magmatic processes still influenced by subducted crustal materials. The dominantly calc-alkaline suites show a shift from normal to high-K to very high-K associations. Source regions are composed of depleted and later enriched orogenic subcontinental lithospheric mantle, affected by dehydration melting and generating more and more K- and LILE-rich magmas. In the vicinity of intra-crustal magma chambers, anatexis by incongruent melting of hydrous minerals may generate peraluminous granitoids bearing mafic enclaves. The post-collision event ends with emplacement of bimodal post-orogenic (PO) suites along transcurrent fault zones. Two suites are defined, (i) the alkali-calcic monzonite-monzogranite-syenogranite-alkali feldspar granite association characterised by [biotite+plagioclase] fractionation and moderate [LILE+HFSE] enrichments and (ii) the alkaline monzonite-syenite-alkali feldspar granite association characterised by [amphibole+alkali feldspar] fractionation and displaying two evolutionary trends, one peralkaline with sodic mafic mineralogy and higher enrichments in HFSE than in LILE, and the other aluminous biotite-bearing marked by HFSE depletion relative to LILE due to accessory mineral precipitation. Alkali-calcic and alkaline suites differ essentially in the amounts of water present within intra-crustal magma chambers, promoting crystallisation of various mineral assemblages. The ultimate enriched and not depleted mantle source is identical for the two PO suites. The more primitive LILE and HFSE-rich source rapidly replaces the older orogenic mantle source during lithosphere delamination and becomes progressively the thermal boundary layer of the new lithosphere. Present rock compositions are a mixture of major mantle contribution and various crustal components

  18. Alkalis and Skin.

    PubMed

    Greenwood, John E; Tan, Jin Lin; Ming, Justin Choong Tzen; Abell, Andrew D

    2016-01-01

    The aim of this editorial is to provide an overview of the chemical interactions occurring in the skin of our patients on contact with alkaline agents. Strongly basic alkali is highly aggressive and will readily hydrolyze (or cleave) key biological molecules such as lipids and proteins. This phenomenon is known as saponification in the case of lipids and liquefactive denaturation for peptides and proteins. A short section on current first-aid concepts is included. A better understanding of the basic science behind alkali burns will make us better teachers and provide an insight into the urgency needed in treating these common and dangerous chemical injuries. PMID:26182072

  19. QUARTZ FIBER ELECTROSCOPES

    DOEpatents

    Henderson, R.P.

    1956-04-17

    This patent pertains to quartz fiber electroscopes of small size for use by personnel to monitor nuclear radiation. The invention resides tn a novel way of charging the electroscope whereby the charging of the electroscope whereby the charging of the electroscope is carried out without obtaining contact with the fiber system or its support and the electroscope can therefore be constructed without a protective cap to prevent wrongful discharge. The electroscope is charged by placing a voltage between an electrode located in close proximity to the element to be charged and the electroscope me metallic case. ABSTRACTS

  20. Progressive hydrothermal alteration of feldspars from the Comstock Lode Region, Nevada: Submicron elemental imaging by Time of Flight-SIMS

    NASA Astrophysics Data System (ADS)

    Handler, M. R.; Vicenzi, E. P.; Sorensen, S. S.

    2002-05-01

    Time of Flight-Secondary Ionization Mass Spectrometry (ToF-SIMS) allows elemental mapping and depth profiling at lateral and depth resolutions of several hundred nanometers, with near-simultaneous acquisition of the entire elemental mass range and extending to larger hydrocarbon molecules. ToF-SIMS has been greatly utilized by surface scientists, but has rarely been used in terrestrial geosciences (e.g. [1]). Essentially a surface imaging technique, with shallow depth profiling abilities, it is ideal for investigating the distribution of elements and molecules (e.g. OH) on mineral surfaces, thin films [1], around fluid inclusions, and to trace chemical changes during weathering or hydrothermal alteration. To illustrate the potential of this analytical technique we highlight the progressive hydrothermal alteration of feldspars in the host andesites of the Comstock Lode paleohydrothermal system, Nevada. The Miocene Comstock Lode and related Ag-Au deposits are hosted mainly within Miocene Alta andesites, which were extensively sampled in the 1880s by G.F. Becker[2]. A sub-suite of these samples from the Sutro Tunnel document progressive hydrothermal alteration, with whole rock δ 18O values progressing from ~ +6 ‰ in distal andesites to -1.5 ‰ at the Coryell Lode [3]. The andesites are porphyritic with up to 50% feldspar phenocrysts, and minor mafic phases. Feldspar phenocrysts show systematic progression of alteration and replacement textures with decreasing whole rock δ 18O values and increasing proximity to the Coryell Lode. Relatively fresh igneous zoned phenocrysts (An35-55) grade into grains with fluid inclusions, crosscutting calcite +/- quartz veins, and increasingly complex reaction rims. Chemical alteration of feldspar progresses along cracks filled with fluid inclusions. Within 400 m of the Coryell Lode, feldspar phenocrysts have fully recrystallized, following crystallographic controls: Ab98-90 + An58-68, +/- sericite +/- calcite. A combination of BSE

  1. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  2. P-T-D histories from quartz: A case study of the application of the TitaniQ thermobarometer to progressive fabric development in metapelites

    NASA Astrophysics Data System (ADS)

    Ashley, Kyle T.; Webb, Laura E.; Spear, Frank S.; Thomas, Jay B.

    2013-09-01

    This study investigates the ability of quartz to record segments of the pressure-temperature-deformation (P-T-D) path in poly-deformed metamorphic terranes and the associated application of the Ti-in-quartz thermobarometer (TitaniQ). Metapelites from the Strafford Dome (eastern Vermont) were selected for this study because they record progressive fabric development during prograde metamorphism and have well constrained P-T-D histories from previous work. Results of this investigation are in agreement with previous studies and demonstrate that quartz in these samples records additional distinct intervals of the P-T-D path. Six preserved quartz equilibration events include: (1) early prograde growth during burial; (2) kyanite-in quartz-producing reactions; (3) prenappe emplacement equilibration during isobaric heating; (4) precipitation of quartz in quartz-feldspar domains during crenulation cleavage development due to solution transfer; (5) quartz-producing (chlorite-out) reactions during heating postnappe emplacement; and (6) retrograde quartz overgrowths from an influx of siliceous fluids. Modeling quartz volume allows for the identification of quartz-producing reactions in P-T space; the same may be done for Ti-phases to better constrain activities during reequilibration events. An integration of cathodoluminescence imaging, microstructural and petrographic investigation, isochemical forward stability modeling, and thermobarometry allows identification and interpretation of zoning patterns in quartz to unravel histories that would otherwise not be obtainable.

  3. Methods of recovering alkali metals

    DOEpatents

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  4. Sr and Pb isotopic geochemistry of feldspars and implications for the growth of megacrysts in plutonic settings.

    NASA Astrophysics Data System (ADS)

    Munnikhuis, J.; Glazner, A. F.; Coleman, D. S.; Mills, R. D.

    2015-12-01

    Why megacrystic textures develop in silicic igneous rocks is still unknown. One hypothesis is that these crystals nucleate early in a magma chamber with a high liquid content. A supportive observation of this hypothesis is areas in plutons with high concentrations of megacrysts suggesting flow sorting. Another group of hypotheses suggest megacrystic textures form during protracted late-stage coarsening in a low-melt, interlocked matrix due to either thermal oscillations from incremental pluton emplacement, or Ostwald ripening. Isotopic analyses of large, euhedral K-feldspar megacrysts from the Cretaceous intrusive suites of the Sierra Nevada batholith (SNB) provide new insight into their origin. Megacrysts from the SNB reach the decimeter scale, are Or rich (85-90%), are perthitic, and host mineral inclusions of nearly all phases in the host rock. In-situ micro-drilling of transects, from core to rim, of the alkali feldspars provides material for Sr and Pb isotopic analyses by thermal ionization mass spectrometry (TIMS). Preliminary 87Sr/86Sr(i) isotopic data from samples from the Cathedral Peak Granodiorite, of the Tuolumne Intrusive Suite range from 0.706337 to 0.706452 (~1.6ɛSr) near the cores, whereas a sawtooth pattern with larger variability, 0.706179 to 0.706533 (~5ɛSr), occurs nears the rims. We interpret these preliminary data to indicate that the late portion of growth (i.e. crystal rim) was dominated by either cannibalism of small K-feldspar crystals with isotopic variability, or by addition of isotopically diverse late components to the magma. By comparing the Sr and Pb isotopic stratigraphy of megacrysts from a variety of rock matrices and different granitoids in the SNB isotopic trends can be evaluated to determine if crystals sizes are dependent on disequilibrium processes or grow at a steady state.

  5. Chlor-Alkali Technology.

    ERIC Educational Resources Information Center

    Venkatesh, S.; Tilak, B. V.

    1983-01-01

    Chlor-alkali technology is one of the largest electrochemical industries in the world, the main products being chlorine and caustic soda (sodium hydroxide) generated simultaneously by the electrolysis of sodium chloride. This technology is reviewed in terms of electrochemical principles and manufacturing processes involved. (Author/JN)

  6. Insights Into the Formation of Rhyolite From the Searchlight Pluton: Evidence from Oriented Quartz Clusters

    NASA Astrophysics Data System (ADS)

    Froemming, N.; Deering, C. D.; Beane, R. J.; Bachmann, O.

    2012-12-01

    The Miocene Searchlight pluton (SLP) in the Colorado River extensional corridor of southern Nevada, is well-exposed and tilted near-vertical for exceptional cross-sectional study of magma reservoir dynamics and crystal fractionation of a mid- to upper-crustal pluton (3 to 13 km depth). The upper quartz monzonite section is dominated by minerals in apparent random orientation with a medium- to fine-grained texture due to direct contact with the cold host rock. The middle granitic section is dominated by coarse-grained quartz and feldspar, and interpreted to be a zone of extracted liquid from an intermediate magma. The lower monzonite section is composed of coarse-grained plagioclase and potassium feldspar. We used the crystallographic orientations of quartz clusters, as determined by Electron Backscatter Diffraction (EBSD), to test for crystal accumulation in the SLP. Clusters of quartz crystals with matched dipyramidal faces (parallel or Esterel twin orientation) may indicate a period of crystal accumulation. By analyzing representative samples from each section of the pluton, we found that the lower section (intermediate cumulate) and upper section (crystallization front) do not have quartz clusters with matched dipyramidal faces. Although plagioclase grains are aligned in the lower section, the late crystallization of quartz appears to have prevented aligned or preferred growth orientations. In contrast, the middle section has a high percentage of quartz clusters with matched dipyramidal faces - similar to that found in granite porphyry of the Vinalhaven pluton, Maine. The aligned grains may have formed by fractional crystallization, compaction and synneusis of the early forming quartz in this granitic section. We interpret the middle section of the Searchlight pluton as being similar to shallow, upper crustal plutons (3-8 km depth) such as Vinalhaven pluton. The deep vertical exposure of the SLP, shows that the middle section was formed from periodic episodes of

  7. ORIGIN OF QUARTZ IN COAL.

    USGS Publications Warehouse

    Ruppert, Leslie F.; Cecil, C. Blaine; Stanton, Ronald W.

    1984-01-01

    Both a scanning electron microscope and an electron microprobe (EMP) were used in this study to analyze the cathodoluminescence properties of quartz grains in samples of the Upper Freeport coal bed because quartz grains in coal are small (silt sized) and below the resolution capabilities of a standard luminoscope. Quartz grains were identified by the detection of silicon alone with energy dispersive X-ray units attached to both the SEM and the EMP.

  8. Mesoscale Approach to Feldspar Dissolution: Quantification of Dissolution Incongruency Based on Al/Si Ordering State

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Min, Y.; Jun, Y.

    2012-12-01

    Dissolution mechanism of aluminosilicates is important for understanding natural and anthropogenic carbon cycles. The total mass of atmospheric CO2 is regulated by the weathering of silicate minerals, and the fate of geologically sequestered CO2 is affected by the interactions between brine, sandstone, caprock, and CO2, which is initiated by mineral dissolution. It has been shown through both experimental and ab initio studies that the dissolution/weathering reactivities of Al and Si in the matrix of an aluminosilicate can be different under many conditions. A subsequent observation is that the release rates of Al and Si, both from the same mineral, may not be stoichiometric when compared to the bulk chemistry of the mineral. For a very long time, the relationship between mineral dissolution incongruency and mineral crystallographic properties remain largely qualitative and descriptive. Here we study the dissolution incongruency of feldspars, the most abundant aluminosilicate on earth. Mineral dissolution experiments for a series of alkali feldspars (albite, anorthoclase, sanidine, and microcline) and plagioclases (oligoclase, andesine, labradorite, bytownite, and anorthite) were conducted at pH 1.68 under ambient conditions. Synchrotron-based X-ray diffraction (HR-XRD), Fourier transform infrared spectroscopy (FTIR), and water chemistry analysis (ICP-MS) are combined to examine the effect of Al/Si ordering on mineral dissolution. Our analysis based on a C1 structure model shows that the incongruency, stemming from the different reactivities of Al-O-Si and Si-O-Si linkages in feldspar's framework, is quantifiable and closely related to the Al/Si ordering state of a feldspar. Our results also suggest that the more random the Al/Si distribution of a mineral, the greater the dissolution incongruency. Our results have significant implications for understanding water-rock interactions. First, when studying the effect of water chemistry on water-rock interaction, smaller

  9. Visible/Near-Infrared Spectra of Experimentally Shocked Plagioclase Feldspars

    NASA Technical Reports Server (NTRS)

    Johnson, J. R.

    2003-01-01

    Minerals subjected to high shock pressures exhibit structural changes with increasing pressure (e.g., fractures, deformations, formation of diaplectic glass, and complete melting [1-6]). Petrologic and thermal infrared spectroscopic studies have shown that diaplectic glass (maskelynite) formation in feldspars occurs between 25-45 GPa, while significant melting occurs above 45 GPa [7- 12]. Past studies of visible/near-infrared spectra of shocked plagioclase feldspars demonstrated few variations in spectral features with pressure except for a decrease in the absorption feature near 1250 nm and an overall decrease in albedo [13-17]. We report new visible/near-infrared spectra of albite- and anorthiterich rocks experimentally shocked from 17-56 GPa.

  10. Visible/near-infrared spectra of experimentally shocked plagioclase feldspars

    USGS Publications Warehouse

    Johnson, J. R.; Horz, F.

    2003-01-01

    High shock pressures cause structural changes in plagioclase feldspars such as mechanical fracturing and disaggregation of the crystal lattice at submicron scales, the formation of diaplectic glass (maskelynite), and genuine melting. Past studies of visible/ near-infrared spectra of shocked feldspars demonstrated few spectral variations with pressure except for a decrease in the depth of the absorption feature near 1250-1300 nm and an overall decrease in reflectance. New visible/near-infrared spectra (400-2500 nm) of experimentally shocked (17-56 GPa) albite- and anorthite-rich rock powders demonstrate similar trends, including the loss of minor hydrated mineral bands near 1410, 1930, 2250, and 2350 nm. However, the most interesting new observations are increases in reflectance at intermediate pressures, followed by subsequent decreases in reflectance at higher pressures. The amount of internal scattering and overall sample reflectance is controlled by the relative proportions of micro-fractures, submicron grains, diaplectic glass, and melts formed during shock metamorphism. We interpret the observed reflectance increases at intermediate pressures to result from progressively larger proportions of submicron feldspar grains and diaplectic glass. The ensuing decreases in reflectance occur after diaplectic glass formation is complete and the proportion of genuine melt inclusions increases. The pressure regimes over which these reflectance variations occur differ between albite and anorthite, consistent with thermal infrared spectra of these samples and previous studies of shocked feldspars. These types of spectral variations associated with different peak shock pressures should be considered during interpretation and modeling of visible/near-infrared remotely sensed spectra of planetary and asteroidal surfaces.

  11. OSL-thermochronometry of feldspar from the KTB borehole, Germany

    NASA Astrophysics Data System (ADS)

    Guralnik, Benny; Jain, Mayank; Herman, Frédéric; Ankjærgaard, Christina; Murray, Andrew S.; Valla, Pierre G.; Preusser, Frank; King, Georgina E.; Chen, Reuven; Lowick, Sally E.; Kook, Myungho; Rhodes, Edward J.

    2015-08-01

    The reconstruction of thermal histories of rocks (thermochronometry) is a fundamental tool both in Earth science and in geological exploration. However, few methods are currently capable of resolving the low-temperature thermal evolution of the upper ∼2 km of the Earth's crust. Here we introduce a new thermochronometer based on the infrared stimulated luminescence (IRSL) from feldspar, and validate the extrapolation of its response to artificial radiation and heat in the laboratory to natural environmental conditions. Specifically, we present a new detailed Na-feldspar IRSL thermochronology from a well-documented thermally-stable crustal environment at the German Continental Deep Drilling Program (KTB). There, the natural luminescence of Na-feldspar extracted from twelve borehole samples (0.1-2.3 km depth, corresponding to 10-70 °C) can be either (i) predicted within uncertainties from the current geothermal gradient, or (ii) inverted into a geothermal palaeogradient of 29 ± 2 °C km-1, integrating natural thermal conditions over the last ∼65 ka. The demonstrated ability to invert a depth-luminescence dataset into a meaningful geothermal palaeogradient opens new venues for reconstructing recent ambient temperatures of the shallow crust (<0.3 Ma, 40-70 °C range), or for studying equally recent and rapid transient cooling in active orogens (<0.3 Ma, >200 °C Ma-1 range). Although Na-feldspar IRSL is prone to field saturation in colder or slower environments, the method's primary relevance appears to be for borehole and tunnel studies, where it may offer remarkably recent (<0.3 Ma) information on the thermal structure and history of hydrothermal fields, nuclear waste repositories and hydrocarbon reservoirs.

  12. Visible/near-infrared spectra of experimentally shocked plagioclase feldspars

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey R.; Hörz, Friedrich

    2003-11-01

    High shock pressures cause structural changes in plagioclase feldspars such as mechanical fracturing and disaggregation of the crystal lattice at submicron scales, the formation of diaplectic glass (maskelynite), and genuine melting. Past studies of visible/near-infrared spectra of shocked feldspars demonstrated few spectral variations with pressure except for a decrease in the depth of the absorption feature near 1250-1300 nm and an overall decrease in reflectance. New visible/near-infrared spectra (400-2500 nm) of experimentally shocked (17-56 GPa) albite- and anorthite-rich rock powders demonstrate similar trends, including the loss of minor hydrated mineral bands near 1410, 1930, 2250, and 2350 nm. However, the most interesting new observations are increases in reflectance at intermediate pressures, followed by subsequent decreases in reflectance at higher pressures. The amount of internal scattering and overall sample reflectance is controlled by the relative proportions of micro-fractures, submicron grains, diaplectic glass, and melts formed during shock metamorphism. We interpret the observed reflectance increases at intermediate pressures to result from progressively larger proportions of submicron feldspar grains and diaplectic glass. The ensuing decreases in reflectance occur after diaplectic glass formation is complete and the proportion of genuine melt inclusions increases. The pressure regimes over which these reflectance variations occur differ between albite and anorthite, consistent with thermal infrared spectra of these samples and previous studies of shocked feldspars. These types of spectral variations associated with different peak shock pressures should be considered during interpretation and modeling of visible/near-infrared remotely sensed spectra of planetary and asteroidal surfaces.

  13. Europium anomaly in plagioclase feldspar: experimental results and semiquantitative model.

    PubMed

    Weill, D F; Drake, M J

    1973-06-01

    The partition of europium between plagioclase feldspar and magmatic liquid is considered in terms of the distribution coefficients for divalent and trivalent europium. A model equation is derived giving the europium anomaly in plagioclase as a function of temperature and oxygen fugacity. The model explains europium anomalies in plagioclase synthesized under controlled laboratory conditions as well as the variations of the anomaly observed in natural terrestrial and extraterrestrial igneous rocks. PMID:17806582

  14. Quartz CPO in a polymineralic ultramylonite

    NASA Astrophysics Data System (ADS)

    Kilian, R.; Heilbronner, R.; Stünitz, H.

    2012-04-01

    Polymineralic ultramylonites often show microstructures indicative of diffusion creep. Disintegration of monomineralic aggregates and phase mixing inhibits dislocation creep of single phases. Grain boundary sliding can lead to rigid body rotation of individual grains and low differential stresses prevent dislocation glide to occur at a significant rate. Thus, grain boundary sliding and low differential stresses usually preclude the presence of a strong crystallographic preferred orientation (CPO). The Truzzo granite in the Central Alps (Italy) hosts ultramylonitic shear zones which formed under amphibolite facies conditions. At high strain quartz aggregates with a preexisting CPO disintegrate and form a grain-scale phase mixture together with oligoclase, biotite and K-feldspar. Within the ultramylonite quartz CPOs are very weak but distinct from random. Shape and size dependent CPOs and CPO-dependent shapes have been analyzed by means of computer integrated polarization microscopy, EBSD and image analysis techniques. In partially mixed layers, larger grains (> 50 µm), which are more elongated (axial ratio > 0.5) and have a small angle between the grain long axis and the lineation, show a preferred c-axis orientation close to the lineation. This is usually interpreted to result from prism [c] slip. Smaller grains (< 50 µm) with more equant shapes show a peripheral c-axis orientation at a high angle to the lineation, inclined against the sense of shear. At the highest degree of phase mixing, only a peripheral c-axis maximum is observed, which is inclined against the sense of shear. This CPO type is different from what would typically occur in monomineralic quartz aggregates, which are deformed by dominant simple shear. Larger grains (> 50 µm) contain abundant low angle boundaries. Analysis of the intragranular crystallographic misorientation indicates that at least some low angle boundaries can be attributed to subgrain boundaries related to the basal or prism

  15. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  16. Quartz resonator processing system

    DOEpatents

    Peters, Roswell D. M.

    1983-01-01

    Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

  17. Dual quartz crystal microbalance

    SciTech Connect

    Dunham, G.C.; Benson, N.H.; Petelenz, D.; Janata, J. )

    1995-01-15

    Construction and performance of a dual quartz crystal microbalance is described. The final probe has a dipstick configuration that is particularly suitable for sensing and monitoring applications in viscous and/or conducting liquids. The differential (heterodyned) frequency measurement substantially eliminates the deleterious effects of viscosity, temperature, and conductivity. The corresponding performance coefficients are temperature df/dT = 1.5 Hz/[degree]C, viscosity df/d[eta][sub L] = 103 Hz/cP, and conductivity df/dM = 108 Hz/M, where conductivity is expressed in terms of molarity of sodium chloride. As an example, the etching of a 2000-A-thick layer of aluminum has been monitored as a function of time. 13 refs., 8 figs., 1 tab.

  18. Alkali basalts and enclosed ultramafic xenoliths near Ushuaia, Tierra Del Fuego, Argentina.

    PubMed

    Acevedo, Rogelio Daniel

    2016-01-01

    At the southernmost part of Tierra del Fuego a few outcrops and erratic boulders of alkali basaltic rocks with ultramafic enclaves have been studied. Alkali basalt plugs or pipes hitherto identified are scarce, and host rocks are constituted by slates that belong to Mesozoic deposition. The petrography, texture and composition of the basalt and xenoliths were investigated by petrographic microscope and electron microprobe analysis. Xenocrysts of amphibole and alkali feldspar, phenocrysts of nepheline, olivine, spinel, phlogopite and Fe-Ti minerals (10 %) and a diversity of xenoliths, mainly lherzolitic, pyroxenite and wehrlitic nodules (15 %), but also from metamorphic rocks provenance, are contained in the basalt groundmass (75 %). This finer-grained material is made up of laths or needles of plagioclase, pyroxene, opaque minerals, apatite and glass, with intersertal, hyalopilitic and pilotaxitic. Locally, rock has an even granoblastic texture. Former amygdules are filled by analcite, zeolites, sodalite and calcite. The normative classification, based on nepheline content, conclude that this rock is an alkali basalt. The chemical classification, considering immobile elements as Zr/TiO2 versus Nb/Y indicate an alkali basalt too and plots over the TAS diagram fall in the foidite (Na-rich or nephelinite) and basanite fields. The REE patterns are fractionated (La/Yb primitive mantle normalized is approximately 30). The K-Ar isotopic technique on individual macrocrysts gave ages of 146 ± 5 Ma (amphibole) and 127 ± 4 Ma (alkali feldspar); and K-Ar whole rock datum reported 8.3 ± 0.3 Ma. Nevertheless, fertile samples show geochemical features typical of deep derived material thus, based on the position in the actual tectonic setting, indicate that the basalt is older than its isotopic age. PMID:27610313

  19. MDD Analysis of Microtexturally Characterized K-Feldspar Fragments

    NASA Astrophysics Data System (ADS)

    Short, C. H.; Heizler, M. T.; Parsons, I.; Heizler, L.

    2011-12-01

    Multiple diffusion domain (MDD) analysis of K-feldspar 40Ar/39Ar age spectra is a powerful thermochronological tool dating back 25 years, but continued validation of the basic assumptions of the model can be afforded by microanalysis of K-feldspar crystal fragments. MDD theory assumes that diffusion of Ar in K-feldspars is controlled by domains of varying size bounded by infinitely fast diffusion pathways. However, the physical character of these domain boundaries is not fully understood and this issue remains a point of criticism of the MDD model. We have evaluated the relationship between texture, age, and thermal history via step heating and modeling of texturally characterized K-feldspar crystal fragments (250-500 μm). K-feldspar phenocrysts from the Shap granite, chosen for their well-studied and relatively simple microtextures, contain large areas of homogenous regular strain-controlled film perthite with periodicities on the order of ~1 μm and abundant misfit dislocations, as well as areas of much coarser, irregular, slightly turbid, patch and vein perthite. Total gas ages (TGA) for all Shap fragments, regardless of texture, show less than 2% variation, but the shape of the age spectra varies with microtexture. Film perthites produce flat spectra whereas patch/vein perthite spectra have initial steps 5 - 25% older than the age of the emplacement with younger plateau or gently rising steps afterward. Patch/vein perthites have substantial microporosity and their spectral shapes may be a consequence of trapped 40Ar* that has diffused into micropores or other defects that have no continuity with the crystal boundaries. Correlations between spectral shape and heating schedule suggest that initial old ages are produced by the early release of trapped 40Ar* separated from the K parent rather than degassing of excess 40Ar*. The MH-42 K-feldspar from the Chain of Ponds Pluton has two primary microtextures: a coarse patch/vein perthite with lamellae 1-20 μm in

  20. Simple model potential and model wave functions for (H-alkali)+ and (alkali-alkali)+ ions

    NASA Astrophysics Data System (ADS)

    Patil, S. H.; Tang, K. T.

    2000-07-01

    A simple model potential is proposed to describe the interaction of a valence electron with the alkali core, which incorporates the correct asymptotic behavior in terms of dipolar polarizabilities, and the short-range exchange effects in terms of a hard core adjusted to give the correct energy for the valence electron. Based on this potential, simple wave functions are developed to describe the (H-alkali)+ and (alkali-alkali)+ ions. These wave functions exhibit some important structures of the ions, and provide a universal description of the properties of all (H-alkali)+ and (alkali-alkali)+ ions, in particular, the equilibrium separations of the nuclei and the corresponding dissociation energies. They also allow us to calculate the dipolar polarizabilities of Li2+, Na2+, K2+, Rb2+, and Cs2+.

  1. Geology of quartz and hydrated silica-bearing deposits near Antoniadi Crater, Mars

    NASA Astrophysics Data System (ADS)

    Smith, Matthew R.; Bandfield, Joshua L.

    2012-06-01

    The only area on Mars where crystalline quartz has been identified from orbit is near Antoniadi Crater, on the northern edge of the Syrtis Major shield volcano. However, the method of quartz formation has remained unknown. In this study, we use high-resolution satellite imagery as well as thermal and near-infrared spectroscopy to construct a geologic history of these deposits and their local context. We find that the quartz-bearing deposits are consistently co-located with hydrated silica. This spatial coherence suggests that the quartz formed as a diagenetic product of amorphous silica, rather than as a primary igneous mineral. Diagenetic quartz is a mature alteration product of hydrated amorphous silica, and indicates more persistent water and/or higher temperatures at this site. Beneath the silica-bearing rocks, we also find spectral evidence for smectites in the lowermost exposed Noachian-aged breccia. A similar stratigraphic sequence — smectite-bearing breccias beneath deposits containing minerals suggesting a greater degree of alteration — has also been found at nearby exposures at Nili Fossae and Toro Crater, suggesting a widespread sequence of alteration. By merging the mineral detections of thermal infrared (quartz, feldspar) and near-infrared spectroscopy (hydrated silica, smectite clays) we are able to construct a more complete geologic history from orbit.

  2. Alkali-vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.; Krupke, W. F.

    2010-02-01

    We report on the results from several of our alkali laser systems. We show highly efficient performance from an alexandrite-pumped rubidium laser. Using a laser diode stack as a pump source, we demonstrate up to 145 W of average power from a CW system. We present a design for a transversely pumped demonstration system that will show all of the required laser physics for a high power system.

  3. Quartz crystal fabrication facility

    NASA Astrophysics Data System (ADS)

    Ney, R. J.

    1980-05-01

    The report describes the design and operation of a five chamber, interconnected vacuum system, which is capable of cleaning, plating, and sealing precision quartz crystal units in ceramic flatpack enclosures continuously in a high vacuum environment. The production rate design goal was 200 units per eight hour day. A unique nozzle beam gold deposition source was developed to operate for extended periods of time without reloading. The source puts out a narrow beam of gold typically in the order of 2 1/2 deg included cone angle. Maximum deposition rates are in the order of 400 a/min at 5.5 in. 'throw' distance used. Entrance and exit air lock chambers expedite the material throughput, so that the processing chambers are at high vacuum for extended periods of time. A stainless steel conveyor belt, in conjunction with three vacuum manipulators, transport the resonator components to the various work stations. Individual chambers are normally separated from each other by gate valves. The crystal resonators, mounted in flatpack frames but unplated, are loaded into transport trays in a lid-frame-lid sequency for insertion into the system and exit as completed crystal units. The system utilizes molybdenum coated ball bearings at essentially all friction surfaces. The gold sources and plating mask heads are equipped with elevators and gate valves, so that they can be removed from the system for maintenance without exposing the chambers to atmosphere.

  4. Hydrogen speciation in synthetic quartz

    USGS Publications Warehouse

    Aines, R.D.; Kirby, S.H.; Rossman, G.R.

    1984-01-01

    The dominant hydrogen impurity in synthetic quartz is molecular H2O. H-OH groups also occur, but there is no direct evidence for the hydrolysis of Si-O-Si bonds to yield Si-OH HO-Si groups. Molecular H2O concentrations in the synthetic quartz crystals studied range from less than 10 to 3,300 ppm (H/Si), and decrease smoothly by up to an order of magnitude with distance away from the seed. OH- concentrations range from 96 to 715 ppm, and rise smoothly with distance away from the seed by up to a factor of three. The observed OH- is probably all associated with cationic impurities, as in natural quartz. Molecular H2O is the dominant initial hydrogen impurity in weak quartz. The hydrolytic weakening of quartz may be caused by the transformation H2O + Si-O-Si ??? 2SiOH, but this may be a transitory change with the SiOH groups recombining to form H2O, and the average SiOH concentration remaining very low. Synthetic quartz is strengthened when the H2O is accumulated into fluid inclusions and cannot react with the quartz framework. ?? 1984 Springer-Verlag.

  5. Thermal infrared spectroscopy and modeling of experimentally shocked plagioclase feldspars

    USGS Publications Warehouse

    Johnson, J. R.; Horz, F.; Staid, M.I.

    2003-01-01

    Thermal infrared emission and reflectance spectra (250-1400 cm-1; ???7???40 ??m) of experimentally shocked albite- and anorthite-rich rocks (17-56 GPa) demonstrate that plagioclase feldspars exhibit characteristic degradations in spectral features with increasing pressure. New measurements of albite (Ab98) presented here display major spectral absorptions between 1000-1250 cm-1 (8-10 ??m) (due to Si-O antisymmetric stretch motions of the silica tetrahedra) and weaker absorptions between 350-700 cm-1 (14-29 ??m) (due to Si-O-Si octahedral bending vibrations). Many of these features persist to higher pressures compared to similar features in measurements of shocked anorthite, consistent with previous thermal infrared absorption studies of shocked feldspars. A transparency feature at 855 cm-1 (11.7 ??m) observed in powdered albite spectra also degrades with increasing pressure, similar to the 830 cm-1 (12.0 ??m) transparency feature in spectra of powders of shocked anorthite. Linear deconvolution models demonstrate that combinations of common mineral and glass spectra can replicate the spectra of shocked anorthite relatively well until shock pressures of 20-25 GPa, above which model errors increase substantially, coincident with the onset of diaplectic glass formation. Albite deconvolutions exhibit higher errors overall but do not change significantly with pressure, likely because certain clay minerals selected by the model exhibit absorption features similar to those in highly shocked albite. The implication for deconvolution of thermal infrared spectra of planetary surfaces (or laboratory spectra of samples) is that the use of highly shocked anorthite spectra in end-member libraries could be helpful in identifying highly shocked calcic plagioclase feldspars.

  6. Genetic significance of the trace element content in metamorphic and hydrothermal quartz: a reconnaissance study

    NASA Astrophysics Data System (ADS)

    Monecke, T.; Kempe, U.; Götze, J.

    2002-09-01

    A reconnaissance study on trace elements in metamorphic and hydrothermal quartz was carried out using quartz samples from the tin district Erzgebirge, Germany, the gold mineralization at Ka\\vsperské Hory, Czech Republic, and the gold-quartz vein deposits Muruntau and Myutenbai, Uzbekistan. A new method of sample preparation has been developed to prepare pure quartz samples by combining conventional hand-picking with microscopic and spectroscopic studies as well as acid wash/etch procedures. Preparation of monomineralic samples was followed by sample dissolution and measurement by ICP-MS. The metamorphic quartz has very low concentrations of Li (≤0.4 ppm), Al (≤30 ppm), K (≤35 ppm), Rb (≤50 ppb), Sr (≤0.3 ppm), and Y (≤15 ppb). Moreover, it is characterized by light rare earth element enriched lanthanide distribution patterns lacking Eu anomalies. The low element concentrations in metamorphic quartz are interpreted to result from recrystallization. Metamorphic quartz from alteration halos enveloping tin and gold deposits has distinctly different trace element signatures. These differences are related to the hydrothermal overprint of the pre-existing metamorphic quartz by the mineralizing fluids. Hydrothermally altered metamorphic quartz from tin deposits has elevated concentrations of Li (≥0.9 ppm), Al (≥50 ppm), K (≥45 ppm), Rb (≥250 ppb), and Y (≥40 ppb) whereas altered metamorphic quartz from gold deposits is characterized by elevated concentrations of Sr (≥0.5 ppm). The rare earth element distribution patterns of altered metamorphic quartz show variable enrichments of the heavy rare earth elements and frequently display positive Eu anomalies. Hydrothermal vein quartz from the gold deposits usually has elevated Al (≥50 ppm) and Sr (≥0.6 ppm) contents. The lanthanide distribution patterns exhibit variable enrichments of the heavy rare earth elements and commonly show positive Eu anomalies. The elevated Sr concentrations in the quartz

  7. Release characteristics of alkali and alkaline earth metallic species during biomass pyrolysis and steam gasification process.

    PubMed

    Long, Jiang; Song, Hu; Jun, Xiang; Sheng, Su; Lun-Shi, Sun; Kai, Xu; Yao, Yao

    2012-07-01

    Investigating the release characteristics of alkali and alkaline earth metallic species (AAEMs) is of potential interest because of AAEM's possible useful service as catalysts in biomass thermal conversion. In this study, three kinds of typical Chinese biomass were selected to pyrolyse and their chars were subsequently steam gasified in a designed quartz fixed-bed reactor to investigate the release characteristics of alkali and alkaline earth metallic species (AAEMs). The results indicate that 53-76% of alkali metal and 27-40% of alkaline earth metal release in pyrolysis process, as well as 12-34% of alkali metal and 12-16% of alkaline earth metal evaporate in char gasification process, and temperature is not the only factor to impact AAEMs emission. The releasing characteristics of AAEMs during pyrolysis and char gasification process of three kinds of biomass were discussed in this paper. PMID:22525260

  8. The effect of SEM imaging on the Ar/Ar system in feldspars

    NASA Astrophysics Data System (ADS)

    Flude, S.; Sherlock, S.; Lee, M.; Kelley, S. P.

    2010-12-01

    Complex microtextures form in K-feldspar crystals as they cool and are affected by deuteric alteration. This complex structure is the cause of variable closure temperatures for Ar-Ar, a phenomenon which has been utilized in multi domain diffusion (MDD) modelling to recover thermal histories [1]. However, there has been substantial controversy regarding the precise interaction between feldspar microtextures and Ar-diffusion [2,3]. A number of studies have addressed this issue using coupled SEM imaging and Ar/Ar UV laser ablation microprobe (UV-LAMP) analysis on the same sample, to enable direct comparison of microtextures with Ar/Ar age data [4]. Here we have tested the idea that SEM work may affect Ar/Ar ages, leading to inaccurate results in subsequent Ar/Ar analyses. Three splits of alkali feldspar from the Dartmoor Granite in SW England were selected for Ar/Ar UV-LAMP analysis. Split 1 (“control”) was prepared as a polished thick section for Ar/Ar analysis. Split 2 (“SEM”) was prepared as a polished thick section, was chemically-mechanically polished with colloidal silica and underwent SEM imaging (uncoated) and focussed ion beam (FIB) milling (gold coated); electron beam damage in the SEM was maximised by leaving the sample at high magnification for eight minutes. Split 3 (“Etch”) is a cleavage fragment that was etched with HF vapour and underwent low to moderate magnification SEM imaging. The control split gave a range of laser-spot ages consistent with the expected cooling age of the granite and high yields of radiogenic 40Ar* (>90%). The area of the “SEM” split that experienced significant electron beam damage gave younger than expected ages and 40Ar* yields as low as 57%. These are interpreted as a combination of implantation of atmospheric Ar and local redistribution of K within the sample. The area of “SEM” that underwent FIB milling gave ages and 40Ar* yields comparable to the control split, suggesting that the Au-coat minimises FIB

  9. Adsorption on Alkali Halides.

    NASA Astrophysics Data System (ADS)

    Urzua Duran, Gilberto Antonio

    1995-01-01

    Using a variety of interionic potentials, I have computed the configurations of adsorbed alkali halides monomers on the (001) surface of selected alkali halides crystals. In the majority of cases studied it is found that the monomer adsorbs perpendicular to the surface with the cation sitting nearly on top of the surface anion. In about ten percent of the cases though the monomer adsorbs tilted from the vertical. In these cases the ion that is closer to the surface can be the cation or the anion. The effect of polarization forces is found to be important. In order to discuss the effects of surface retaxation with adsorbates, I have evaluated the surface relaxation of the alkali halide crystals, using a shell model for the interionic forces. It is found that surface relaxation and rumpling are generally small, especially when the van der Waals forces are included. A theory of the effect of substrate vibrations on the binding of an adsorbed atom is developed. At T = 0 the binding energy is D_0-E, where D_0 is the surface well depth (classical binding energy) and E is the quantum correction. For several simple models, it is found that E is surprisingly model-independent. We compare D _0-E with the binding energies to a rigid substrate, D_0-E_{rs}, and to a vibrationally averaged substrate, D _0-E_{va}. We prove that E_{va}>=q E>=q E_ {rs} and that similar relations hold at finite temperature for the free energy of binding. In most cases E_{rs} is better than E_{va} as an approximation to E.

  10. Thermoelectrically-cooled quartz microbalance

    NASA Technical Reports Server (NTRS)

    Mckeown, D.

    1975-01-01

    Temperature of microbalance can be maintained at ambient temperature or held at some other desired temperature. Microbalance has tow-stage thermoelectric device that controls temperature of quartz crystal. Heat can be pumped to or from balance by Peltier effect.

  11. Low-temperature multi-OSL-thermochronometry of feldspar

    NASA Astrophysics Data System (ADS)

    King, Georgina; Herman, Frederic; Lambert, Renske; Valla, Pierre; Guralnik, Benny

    2016-04-01

    Constraining exhumation rates and landscape histories over Quaternary timescales represents a major challenge for understanding the interaction between changing climate and erosion processes. Facilitated by closure temperatures of as low as ~30 C, OSL-thermochronometry is able to constrain cooling rates from the top few km of the earth's crust, and offers the potential for recent changes in erosion to be determined. Based on the well-established Quaternary dating technique of optically stimulated luminescence dating, OSL-thermochronometry benefits from a strong methodological and theoretical foundation. A further advantage of OSL-thermochronometry is that it is possible to measure multiple luminescence signals from a single mineral, such as feldspar. Therefore OSL-thermochronometry can be used as a multi-thermochronometer whereby different signals from the same mineral have closure temperatures in the range of 30-70 C, enabling the derivation of very precise cooling histories. However, in contrast to other low-temperature methods, OSL-thermochronometry is limited by signal saturation, restricting its application to either elevated temperature settings (e.g. bore holes, tunnels) or rapidly exhuming terranes. Here we outline the principles of multi-OSL-thermochronometry of feldspar and its potential as a low-temperature thermochronometry system.

  12. Chemical Zoning of Feldspars in Lunar Granitoids: Implications for the Origins of Lunar Silicic Magmas

    NASA Technical Reports Server (NTRS)

    Mills, R. D; Simon, J. I.; Alexander, C.M. O'D.; Wang, J.; Christoffersen, R.; Rahman, Z..

    2014-01-01

    Fine-scale chemical and textural measurements of alkali and plagioclase feldspars in the Apollo granitoids (ex. Fig. 1) can be used to address their petrologic origin(s). Recent findings suggest that these granitoids may hold clues of global importance, rather than of only local significance for small-scale fractionation. Observations of morphological features that resemble silicic domes on the unsampled portion of the Moon suggest that local, sizable net-works of high-silica melt (>65 wt % SiO2) were present during crust-formation. Remote sensing data from these regions suggest high concentrations of Si and heat-producing elements (K, U, and Th). To help under-stand the role of high-silica melts in the chemical differentiation of the Moon, three questions must be answered: (1) when were these magmas generated?, (2) what was the source material?, and (3) were these magmas produced from internal differentiation. or impact melting and crystallization? Here we focus on #3. It is difficult to produce high-silica melts solely by fractional crystallization. Partial melting of preexisting crust may therefore also have been important and pos-sibly the primary mechanism that produced the silicic magmas on the Moon. Experimental studies demonstrate that partial melting of gabbroic rock under mildly hydrated conditions can produce high-silica compositions and it has been suggested by that partial melting by basaltic underplating is the mechanism by which high-silica melts were produced on the Moon. TEM and SIMS analyses, coordinated with isotopic dating and tracer studies, can help test whether the minerals in the Apollo granitoids formed in a plutonic setting or were the result of impact-induced partial melting. We analyzed granitoid clasts from 3 Apollo samples: polymict breccia 12013,141, crystalline-matrix breccia 14303,353, and breccia 15405,78

  13. Lithological influence of aggregate in the alkali-carbonate reaction

    SciTech Connect

    Lopez-Buendia, A.M. . E-mail: angel.lopez@aidico.es; Climent, V. . E-mail: vcliment@grupogla.com; Verdu, P.

    2006-08-15

    The reactivity of carbonate rock with the alkali content of cement, commonly called alkali-carbonate reaction (ACR), has been investigated. Alkali-silica reaction (ASR) can also contribute in the alkali-aggregate reaction (AAR) in carbonate rock, mainly due to micro- and crypto-crystalline quartz or clay content in carbonate aggregate. Both ACR and ASR can occur in the same system, as has been also evidenced on this paper. Carbonate aggregate samples were selected using lithological reactivity criteria, taking into account the presence of dedolomitization, partial dolomitization, micro- and crypto-crystalline quartz. Selected rocks include calcitic dolostone with chert (CDX), calcitic dolostone with dedolomitization (CDD), limestone with chert (LX), marly calcitic dolostone with partial dolomitization (CD), high-porosity ferric dolostone with clays (FD). To evaluate the reactivity, aggregates were studied using expansion tests following RILEM AAR-2, AAR-5, a modification using LiOH AAR-5Li was also tested. A complementary study was done using petrographic monitoring with polarised light microscopy on aggregates immersed in NaOH and LiOH solutions after different ages. SEM-EDAX has been used to identify the presence of brucite as a product of dedolomitization. An ACR reaction showed shrinkage of the mortar bars in alkaline solutions explained by induced dedolomitization, while an ASR process typically displayed expansion. Neither shrinkage nor expansion was observed when mortar bars were immersed in solutions of lithium hydroxide. Carbonate aggregate classification with AAR pathology risk has been elaborated based on mechanical behaviours by expansion and shrinkage. It is proposed to be used as a petrographic method for AAR diagnosis to complement the RILEM AAR1 specifically for carbonate aggregate. Aggregate materials can be classified as I (non-reactive), II (potentially reactive), and III (probably reactive), considering induced dedolomitization ACR

  14. Evaluation of laboratory test method for determining the potential alkali contribution from aggregate and the ASR safety of the Three-Gorges dam concrete

    SciTech Connect

    Lu Duyou . E-mail: duyoulu@njut.edu.cn; Zhou, Xiaoling; Xu Zhongzi; Lan Xianghui; Tang Mingshu; Fournier, Benoit

    2006-06-15

    The releasable alkali from granite, which was used in the Three-Gorges concrete dam project in China, and from gneiss and feldspar was estimated by extraction in distilled water and super-saturated Ca(OH){sub 2} solution. Results show that: i) the finer the particles and the higher the temperature, the greater and faster the release of alkali; ii) compared with extraction by distilled water, super-saturated Ca(OH){sub 2} solution had a stronger activation on feldspar than on granite and gneiss; iii) for the three rocks tested, thermal activation had the largest effect on gneiss and a lower and similar effect on granite and feldspar. For very fine particles, temperature had a similar effect on the release of alkali by all three rocks. Because the aggregate used in the Three-Gorges dam concrete is non-reactive and a low calcium fly ash was used in the concrete, ASR would not be an issue for the dam, despite the release of alkali from the aggregate into the concrete.

  15. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

    A process is described of recovering alkali metal vapor by sorption on activated alumina, activated carbon, dehydrated zeolite, activated magnesia, or Fuller's earth preheated above the vaporization temperature of the alkali metal and subsequent desorption by heating the solvent under vacuum. (AEC)

  16. Preparation of alkali metal dispersions

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Landel, R. F. (Inventor)

    1968-01-01

    A method is described for producing alkali metal dispersions of high purity. The dispersions are prepared by varying the equilibrium solubility of the alkali metal in a suitable organic solvent in the presence of aromatic hydrocarbons. The equilibrium variation is produced by temperature change. The size of the particles is controlled by controlling the rate of temperature change.

  17. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  18. Dissolution of K-feldspar at CO2-saturated conditions

    NASA Astrophysics Data System (ADS)

    Rosenqvist, Jörgen; Kilpatrick, Andrew D.; Yardley, Bruce W. D.; Rochelle, Christopher A.

    2014-05-01

    Underground storage of carbon dioxide on a very large scale is widely considered to be an essential part of any strategy to reduce greenhouse gas emissions to the atmosphere. Aquifers in deep sedimentary basins have been identified as suitable targets for geological carbon dioxide storage, especially aquifers located in sandstone host rock. This has led to renewed interest in studying the interaction between sandstone minerals and aqueous fluids, as there is a paucity of data for CO2-containing systems at relevant conditions. In an attempt to improve data coverage for important silicate minerals, we have measured the dissolution kinetics of K-feldspar in CO2-saturated fluids over a range of temperatures. K-feldspar fragments were hand-picked from a larger sample, crushed to a narrow size range and cleaned. The grains were reacted with water in batch-type reactors at temperatures from 20°C to 200°C and pressures up to 200 bar, and the dissolution was followed by periodic withdrawal of aliquots of solution. The mineral grains were allowed to react with pure water for a number of weeks before injection of CO2 into the system. Excess CO2 was provided to ensure CO2 saturation in the experimental systems. While the reaction time before injection was not long enough to attain complete equilibrium, it did considerably lower the degree of undersaturation with respect to K-feldspar and helped highlight the effect of CO2 injection into a rock-equilibrated aqueous fluid. At all temperatures studied, injection of CO2 resulted in a rapid increase in the soluble concentrations of K and Si (and also Na from a plagioclase component). The dissolution then reached apparent steady state conditions after a few days, with observed dissolution rates in the range of 1E-9 to 1E-12 mol/m2/s over the temperature range studied. The CO2-saturated solutions maintained mildly acidic conditions throughout the experiments and the observed rates therefore fall roughly between rates measured in

  19. Dislocation creep of dry quartz

    NASA Astrophysics Data System (ADS)

    Kilian, Rüdiger; Heilbronner, Renée.; Holyoke, Caleb W.; Kronenberg, Andreas K.; Stünitz, Holger

    2016-05-01

    Small-scale shear zones within the Permian Truzzo meta-granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250-750 µm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/106Si and very little broad band absorption, <100 H/106Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta-granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions.

  20. Role of Substrate on Quartz Cementation in Quartz Aggregates

    NASA Astrophysics Data System (ADS)

    Farver, J. R.; Winslow, D.; Onasch, C.

    2010-12-01

    Quartz cementation in quartz aggregates has been experimentally investigated. The starting material was disaggregated detrital quartz grains from the well-sorted, mature St. Peter Sandstone. The ‘as-is’ grains have patches of iron oxide coatings and some have euhedral overgrowths that contain iron oxide dust rims. In addition a set of experiments was run using grains that were cleaned by soaking in sodium hydrosulfite and sodium bisulfate solutions to remove exposed iron oxide coatings. Experimental charges consisted of amorphous silica powder (≈30 mg) to provide a source of silica for the quartz cement, AlCl3 powder (≈3 mg) to provide a tracer for Cathodoluminescence (CL) identification of cement formed during the experiment, 25 wt% NaCl brine solution (≈25 mg) to increase the silica solubility and to better mimic oil field brines, and the natural quartz grains (100-130 mg). The charges were weld-sealed in Au capsules and run in cold-seal pressure vessels at 250°C to 450°C at 150 MPa confining pressure for up to 8 weeks. After the experiments, the samples were vacuum impregnated with a low viscosity epoxy containing a blue dye. After curing, the sample charge was sawn in half along its long axis and one half was polished (to 1 micron diamond paste) for analysis. The nature and amount of quartz cement in the samples were determined by a combination of CL, light microscopy, and scanning electron microscopy. Photomosaics of the samples were created and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement formed during the experiment was easily recognized from the quartz grains (and previous overgrowths) by the difference in luminescence. The results indicate the amorphous silica powder provides a ready source for silica for quartz cementation due to its greater solubility than the quartz. The cementation rates are rapid (>14% cement formed in 2 weeks at 450°C and >7% in 8 weeks at 250°C). Compared to

  1. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  2. Feldspars Detected by ChemCam in Gale Crater with Implications for Future Martian Exploration

    NASA Astrophysics Data System (ADS)

    Gasda, P. J.; Carlson, E.; Wiens, R. C.; Bridges, J.; Sautter, V.; Cousin, A.; Maurice, S.; Gasnault, O.; Clegg, S. M.

    2015-12-01

    Feldspar is a common igneous mineral that can shed light on parent magma temperatures, pressures, and compositions. During the first 801 sols of the NASA Mars Science Laboratory mission, we have detected 125 possible feldspar grains using the ChemCam LIBS instrument. We analyzed spectra from successive laser shots at the same location and approximate whole rock compositions for each target. Feldspar-containing targets range from tephrite-basanite to trachyandesite. The most common feldspar type is andesine; no targets are >An60. Over 30% are anorthoclase, and ~10% have potassium contents up to Or60. Individual shot measurements in a single spot suggest some feldspars are zoned. Most of these rocks are either float or incorporated into conglomerates, and thus we do not know their provenance. Many of the samples may originate from the Gale crater walls, indicative of Southern Highland ancient crust. Some may also be flung from further away (e.g., emplaced by impact processes). Hence, these rocks may give us a general clue to the variety of evolved igneous materials on Mars. The ubiquity of feldspars at Gale suggests that they have been significantly underestimated for the Southern Highlands, if not for the whole of Mars. For example, significant abundance of andesitic feldspars in both the southern highland and northern lowlands of Mars would imply that Martian volcanism has produced a greater extent of evolved igneous materials to a greater degree than previously thought. Remote sensing instruments are insensitive to plagioclase due to dust cover, lack of exposures, or low feldspar FeO content. However, the Mars 2020 rover will be equipped with 3 new instruments, the arm-mounted SHERLOC Raman, PIXL μXRF, and the mast-mounted SuperCam combined Raman-LIBS instruments, which should help characterize Martian feldspars. Additionally, the SuperCam instrument plans to include three feldspars in its suite of 20+ onboard standards to improve feldspar chemical analysis.

  3. Water Content of Lunar Alkali Fedlspar

    NASA Technical Reports Server (NTRS)

    Mills, R. D.; Simon, J. I.; Wang, J.; Alexander, C. M. O'D.; Hauri, E. H.

    2016-01-01

    Detection of indigenous hydrogen in a diversity of lunar materials, including volcanic glass, melt inclusions, apatite, and plagioclase suggests water may have played a role in the chemical differentiation of the Moon. Spectroscopic data from the Moon indicate a positive correlation between water and Th. Modeling of lunar magma ocean crystallization predicts a similar chemical differentiation with the highest levels of water in the K- and Th-rich melt residuum of the magma ocean (i.e. urKREEP). Until now, the only sample-based estimates of water content of KREEP-rich magmas come from measurements of OH, F, and Cl in lunar apatites, which suggest a water concentration of < 1 ppm in urKREEP. Using these data, predict that the bulk water content of the magma ocean would have <10 ppm. In contrast, estimate water contents of 320 ppm for the bulk Moon and 1.4 wt % for urKREEP from plagioclase in ferroan anorthosites. Results and interpretation: NanoSIMS data from granitic clasts from Apollo sample 15405,78 show that alkali feldspar, a common mineral in K-enriched rocks, can have approx. 20 ppm of water, which implies magmatic water contents of approx. 1 wt % in the high-silica magmas. This estimate is 2 to 3 orders of magnitude higher than that estimated from apatite in similar rocks. However, the Cl and F contents of apatite in chemically similar rocks suggest that these melts also had high Cl/F ratios, which leads to spuriously low water estimates from the apatite. We can only estimate the minimum water content of urKREEP (+ bulk Moon) from our alkali feldspar data because of the unknown amount of degassing that led to the formation of the granites. Assuming a reasonable 10 to 100 times enrichment of water from urKREEP into the granites produces an estimate of 100-1000 ppm of water for the urKREEP reservoir. Using the modeling of and the 100-1000 ppm of water in urKREEP suggests a minimum bulk silicate Moon water content between 2 and 20 ppm. However, hydrogen loss was

  4. The contribution of quartz and the role of aluminum for understanding the AAR with greywacke

    SciTech Connect

    Huenger, Klaus-Juergen E-mail: huenger@tu-cottbus.de

    2007-08-15

    Precambrian Greywacke from Lower Lusatia (Germany) has been well known as an alkali sensitive aggregate for several years. It can cause considerable damages in concrete buildings due to an Alkali-Aggregate-Reaction. The investigations are focused on quartz as the main releaser of silica, its characterization and its behavior in an alkaline solution. But there are no relations between quartz properties and the alkali sensitivities of greywacke samples. To understand this fact the role of aluminum which greywacke releases in different amounts into the alkaline solution too must be considered. Aluminum affects the silica concentration by three different mechanisms. The result is always a decrease of the silica concentration in the solution caused by an alumino silicate formation. The silica bound by alumino silicate structures can be quantified by {sup 27}Al-NMR-spectroscopy. The expansions of concrete samples can now be described much well as a function of a so called 'free' silica. Based on this results a direct test method for the assessment of the alkali sensitivity of greywackes could be created and suggestions for an inhibition can be given.

  5. Fault core and damage zone fracture attributes vary along strike owing to interaction of fracture growth, quartz accumulation, and differing sandstone composition

    NASA Astrophysics Data System (ADS)

    Laubach, S. E.; Eichhubl, P.; Hargrove, P.; Ellis, M. A.; Hooker, J. N.

    2014-11-01

    Small, meter-to decimeter-displacement oblique-slip faults cut latest Precambrian lithic arkose to feldspathic litharenite and Cambrian quartz arenite sandstones in NW Scotland. Despite common slip and thermal histories during faulting, the two sandstone units have different fault-core and damage-zone attributes, including fracture length and aperture distributions, and location of quartz deposits. Fault cores are narrow (less than 1 m), low-porosity cataclasite in lithic arkose/feldspathic litharenites. Damage zone-parallel opening-mode fractures are long (meters or more) with narrow ranges of lengths and apertures, are mostly isolated, have sparse quartz cement, and are open. In contrast, quartz arenites, despite abundant quartz cement, have fault cores that contain porous breccia and dense, striated slip zones. Damage-zone fractures have lengths ranging from meters to centimeters or less, but with distributions skewed to short fractures, and have power-law aperture distributions. Owing to extensive quartz cement, they tend to be sealed. These attributes reflect inhibited authigenic quartz accumulation on feldspar and lithic grains, which are unfavorable precipitation substrates, and favored accumulation on detrital quartz. In quartz breccia, macropores >0.04 mm wide persist where surrounded by slow-growing euhedral quartz. Differences in quartz occurrence and size distributions are compatible with the hypothesis that cement deposits modify the probability of fracture reactivation. Existing fractures readily reactivate in focused growth where quartz accumulation is low and porosity high. Only some existing, partly cemented fractures reactivate and some deformation is manifest in new fracture formation in partitioned growth where quartz accumulation is high. Consequences include along-strike differences in permeability and locus of fluid flow between cores and damage zones and fault strength.

  6. Planar deformation features in quartz from impact-produced polymict breccia of the Xiuyan crater, China

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Koeberl, Christian; Xiao, Wansheng; Xie, Xiande; Tan, Dayong

    2011-05-01

    The 1.8 km-diameter Xiuyan crater is an impact structure in northeastern China, exposed in a Proterozoic metamorphic rock complex. The major rocks of the crater are composed of granulite, hornblendite, gneiss, tremolite marble, and marble. The bottom at the center of the crater covers about 100 m thick lacustrine sediments underlain by 188 m thick crater-fill breccia. A layer of polymict breccia composed of clasts of granulite, gneiss, hornblendite, and fragments of glass as well as clastic matrix, occurs near the base, in the depth interval from 260 to 295 m. An investigation in quartz from the polymict breccia in the crater-fill units reveals abundant planar deformation features (PDFs). Quartz with multiple sets of PDFs is found in clasts of granulite that consist of mainly quartz and feldspar, and in fine-grained matrix of the impact-produced polymict breccia. A universal stage was used to measure the orientation of PDFs in 70 grains of quartz from five thin sections made from the clasts of granulite of polymict breccia recovered at the depth of 290 m. Forty-four percent of the quartz grains contain three sets of PDFs, and another 40% contain two sets of PDFs. The most abundant PDFs are rhombohedron forms of ?, ?, and ? with frequency of 33.5, 22.3, and 9.6%, respectively. A predominant PDF form of ? in quartz suggests a shock pressure >20 GPa. The occurrence of PDFs in quartz from the polymict breccia provides crucial evidence for shock metamorphism of target rocks and confirms the impact origin of this crater, which thus appears to be the first confirmed impact crater in China.

  7. Shocked quartz and more: Impact signatures in K-T boundary clays and claystones

    NASA Technical Reports Server (NTRS)

    Bohor, Bruce F.

    1988-01-01

    Quartz grains displaying multiple sets of planar features are described from numerous Cretaceous-Tertiary (K-T) boundary clays and claystones at both marine and nonmarine depositional sites around the world. All these sites also show anomalously high amounts of iridium and enrichments of other siderophile elements in cosmic ratios within these boundary units. This combination of mineralogical and geochemical features are used in support of an impact hypothesis for the end-Cretaceous event. Recently, it was suggested that some combination of explosive and nonexplosive volcanism associated with the formation of the Deccan traps in India could be responsible for the mineralogy and geochemistry seen in the K-T boundary units. Besides the obvious contradition of simultaneous explosive and nonexplosive volcanism from one locality during an instant of geologic time, there remains the difficulty of spreading both iridium (and trace elements in cosmic proportions) and quartz grains around the world by volcanic (atmospheric) transport. In addition, the ability of volcanism to produce the type of shock metamorphism seen in minerals at the K-T boundary was not demonstrated. Multiple sets of shock lamellae in quartz are considered characteristic of shock metamorphism in rocks at the sites of known impact craters and are the type of deformation seen in quartz from K-T boundary clays and claystones. Single sets of poorly defined lamellae described from rare quartz grains in certain volcanic deposits are characteristic of tectonic deformation and do not correspond to the shock lamellae in quartz from K-T sediments and impact structures. So-called shock mosaicism in quartz and feldspar grains described from volcanic deposits can result from many processes other than shock metamorphism, and therefore is not considered to be an effect characteristic solely of shock. The mineralogy of shock-metamorphosed grains at the K-T boundary also argues against a volcanic origin.

  8. Formation of parting in quartz

    NASA Astrophysics Data System (ADS)

    Jørgen Kjøll, Hans; Eske Sørensen, Bjørn

    2014-05-01

    This paper presents hydrothermal quartz with macroscopic planar parting from the Mesoproterozoic Modum complex in southern Norway. Similar macroscopic parting in hydrothermal quartz with macroscopic planar structures has only been described from two localities in the world; Madagascar (Flörke et al., 1981) and Southern California (Murdoch et al., 1938). The study area consists of well foliated and banded sillimanite- garnet- amphibolite- mica gneiss that is cut at high angle by hydrothermal veins containing albite, chlinoclore, hornblende, hydroxyl apatite and quartz. The rim of the veins is generally made up of almost pure end-member euhedral albite. Then there is vugs with euhedral hornblende (10-25cm long) and euhedral hydroxyl apatite with size ranging from mm scale to several cm. Some places the quartz encloses apatite and hornblende. The quartz is anhedral, inequigranular with undulose extinction bordering sub grain rotation. It has large planar penetrative parting faces with pearly luster; however this is not consistent throughout the outcrop and some places the penetrative faces disappears and the quartz has a conchoidal fracture. The planar faces continue throughout the specimens with a few mm spacing. Thin sections oriented perpendicular to the most pronounced planar structure show lamellas that extinguishes at small angles (2 degrees) to each other. EBSD mapping of the planar faces shows two orientations {0-111} and {1-101}, corresponding to the r- and z-faces respectively, separated by irregular boundaries. The misorientation between these two crystallographic orientations on the parting is a 60 degree rotation on [0 0 1] in correspondence to the dauphiné twin law. Investigations conducted on thin sections cut orthogonal to the parting shows that the parting cuts and offsets the dauphiné twins, indicating a late genesis of the parting. However some internal stress induced movement of the twins are visible. SEM-CL documents three generations of quartz

  9. Feldspar basalts in lunar soil and the nature of the lunar continents

    NASA Technical Reports Server (NTRS)

    Reid, A. M.; Ridley, W. I.; Harmon, R. S.; Warner, J.; Brett, R.; Jakes, P.; Brown, R. W.

    1974-01-01

    It is found that 25% on the Apollo-14 glasses have the same composition as the glasses in two samples taken from the Luna-16 column. The compositions are equivalent to feldspar basalt and anorthosite gabbro, and are similar to the feldspar basalts identified from Surveyor-7 analysis for lunar continents.

  10. Aluminum position in Rb-feldspar as determined by X-ray photoelectron spectroscopy.

    PubMed

    Kyono, Atsushi; Kimata, Mitsuyoshi; Hatta, Tamao

    2003-09-01

    Al/Si configurations in some natural and synthetic Rb-feldspars have been examined carefully by EMPA and XPS analyses. Our results indicate that a small amount of H2O and excess Si and Al are incorporated in hydrothermally synthesized Rb-feldspar. The quantities of excess Al are 0.056 atoms per formula unit and are negatively correlated with those of the Rb, suggesting the presence of excess Al occupying non-tetrahedral sites in feldspar structures. This leads to incorporation of Al(Al3Si)O8 endmember into Rb-feldspars, estimated as one appropriate endmember indication for unusual chemistry of feldspars. In addition, Si2p, Al2p and O1s XPS signals of Rb-feldspars shift drastically toward the higher energy side than those of any natural feldspars. These provide conclusive evidence not only for existence of perceptible excess Si and Al, but also for Al at both extra-framework and tetrahedral sites in feldspar structures. PMID:14504785

  11. Comminution characteristics of quartz in natural and experimental faults; Implications for brittle shear localization

    NASA Astrophysics Data System (ADS)

    Hadizadeh, J.; Konkachbaev, A.; Goldsby, D.

    2004-05-01

    We studied a number of faults in weakly cemented Aztec sandstone (92.6% quartz, 6.1% clay, 1.2% K-feldspar; well/sub-rounded grains; mean grain size 330μ m; porosity 17-24%) from Valley of Fire (VOF) State Park in Nevada, USA, with true displacements 1.5 to150 cm. The deformation is typically asymmetric core/damage zone type microstructure with fault core thickness varying between the samples from 2 to 50mm. Digital optical and SEM images were used to obtain PSD, and fractal dimension (D) of the comminuted quartz with ~4μ m particle segmentation resolution. A shape descriptor algorithm (POL) was used for quantifying particle angularity. The VOF results were compared with those of quartz and feldspars in simulated Westerly granite gouge (WG) sheared at 25MPa pressure. Compared to WG samples of similar displacement, typical VOF fault gouge appears to be less isotropic and includes larger and more survivor particles. The incidence of D values >2.58 seems to correlate with shear localization microstructures regardless of total displacement on the faults. There is considerable reduction in particle angularity with increased displacement in the VOF samples, and higher D values correlate well with lower POL numbers, i.e. comminution results in rounding of quartz particles. Similar correlation of D and POL values is found for the quartz fraction in the WG samples in which feldspar particles become more angular with increased shear displacement. The results provide a tentative basis for relating the evolution of particle geometry to angle of internal friction in active bands within the fault gouge. Our observations support a model in which an episode of displacement on the fault initially generates series of dilatant oblique shears (e.g. a stack of R-shears). The dilatant shears should occur with diminishing frequency as further comminution reduces the band thickness via packing density increases. This process tends to lower the angle of internal friction by reducing the

  12. Upgrading platform using alkali metals

    SciTech Connect

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  13. Laser welding of fused quartz

    DOEpatents

    Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

    2003-06-10

    Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

  14. The Interfacial Transition Zone in Alkali-Activated Slag Mortars

    NASA Astrophysics Data System (ADS)

    San Nicolas, Rackel; Provis, John

    2015-12-01

    The interfacial transition zone (ITZ) is known to strongly influence the mechanical and transport properties of mortars and concretes. This paper studies the ITZ between siliceous (quartz) aggregates and alkali activated slag binders in the context of mortar specimens. Backscattered electron images (BSE) generated in an environmental scanning electron microscope (ESEM) are used to identify unreacted binder components, reaction products and porosity in the zone surrounding aggregate particles, by composition and density contrast. X-ray mapping is used to exclude the regions corresponding to the aggregates from the BSE image of the ITZ, thus enabling analysis of only the binder phases, which are segmented into binary images by grey level discrimination. A distinct yet dense ITZ region is present in the alkali-activated slag mortars, containing a reduced content of unreacted slag particles compared to the bulk binder. The elemental analysis of this region shows that it contains a (C,N)-A-S-H gel which seems to have a higher content of Na (potentially deposited through desiccation of the pore solution) and a lower content of Ca than the bulk inner and outer products forming in the main binding region. These differences are potentially important in terms of long-term concrete performance, as the absence of a highly porous interfacial transition zone region is expected to provide a positive influence on the mechanical and transport properties of alkali-activated slag concretes.

  15. Dissolution rates and surface chemistry of feldspar glass and crystal. Final technical report, June 15, 1995 - August 14, 2001

    SciTech Connect

    Brantley, S.; Pantano, C.

    2002-06-11

    Final report summarizing the completed work of the project entitled 'Dissolution of Feldspar in the Field and Laboratory.' One of the highly debated questions today in low-temperature geochemical kinetics centers upon the rate and mechanism of dissolution of feldspar, the most common mineral in the crust. In this project, the mechanisms of feldspar dissolution were investigated by emphasizing experiments with feldspar glass and crystal while comparing surface and solution chemistry. Specifically, laboratory work focused on the structure of altered surface layers on feldspars, the rate of dissolution of feldspar crystal and glass, and the presence of porosity and surface coatings on feldspars. In a complementary field project, the use of Sr concentrations and isotopic ratios were used to calculate feldspar dissolution rates.

  16. pKa at Quartz/Electrolyte Interfaces.

    PubMed

    Pfeiffer-Laplaud, Morgane; Gaigeot, Marie-Pierre; Sulpizi, Marialore

    2016-08-18

    Acidity of silanol sites at the crystalline quartz/aqueous electrolyte (NaCl, NaI, KCl) interfaces are calculated from ab initio molecular dynamics simulations. pKa's are found to follow a combination of the cationic and anionic Hofmeister series in the order pKa(neat solution) < pKa(NaCl) < pKa(NaI) < pKa(KCl), in agreement with experimental measurements. Rationalization of this ranking is achieved in terms of the microscopic local solvation of the protonated silanols and their conjugated bases, the silanolates SiO(-). The change in the pKa is the result of both water destructuring by alkali halides, as well as of the specific cation/SiO(-) interaction, depending on the electrolyte. Molecular modeling at the atomistic level is required to achieve such comprehension, with ab initio molecular dynamics being able to model complex inhomogeneous charged interfaces and the associated interfacial chemical reactivity. PMID:27483195

  17. Formation of halloysite from feldspar: Low temperature, artificial weathering versus natural weathering

    USGS Publications Warehouse

    Parham, W.E.

    1969-01-01

    Weathering products formed on surfaces of both potassium and plagioclase feldspar (An70), which were continuously leached in a Soxhlet extraction apparatus for 140 days with 7.21 of distilled water per day at a temperature of approximately 78 ??C, are morphologically identical to natural products developed on potassium feldspars weathered under conditions of good drainage in the humid tropics. The new products, which first appear as tiny bumps on the feldspar surface, start to develop mainly at exposed edges but also at apparently random sites on flat cleavage surfaces. As weathering continues, the bumps grow outward from the feldspar surface to form tapered projections, which then develop into wide-based thin films or sheets. The thin sheets of many projections merge laterally to form one continuous flame-shaped sheet. The sheets formed on potassium feldspars may then roll to form tubes that are inclined at a high angle to the feldspar surface. Etch pits of triangular outline on the artificially weathered potassium feldspars serve as sites for development of continuous, non-rolled, hollow tubes. It is inferred from its morphology that this weathering product is halloysite or its primitive form. The product of naturally weathered potassium feldspars is halloysite . 4H2O. The flame-shaped films or sheets formed on artificially weathered plagioclase feldspar do not develop into hollow tubes, but instead give rise to a platy mineral that is most probably boehmite. These plates form within the flame-shaped films, and with continued weathering are released as the film deteriorates. There is no indication from this experiment that platy pseudohexagonal kaolinite forms from any of these minerals under the initial stage of weathering. ?? 1969.

  18. Brittle-viscous deformation of vein quartz under fluid-rich lower greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Kjøll, H. J.; Viola, G.; Menegon, L.; Sørensen, B. E.

    2015-06-01

    We studied by Electron BackScatter Diffraction (EBSD) and optical microscopy a coarse-grained (ca. 0.5-6 mm) quartz vein embedded in a phyllonitic matrix to gain insights into the recrystallization mechanisms and the processes of strain localization in quartz deformed under lower greenschist facies conditions, broadly coincident with the brittle-viscous transition. The vein deformed during faulting along a phyllonitic thrust of Caledonian age within the Porsa Imbricate Stack in the Paleoproterozoic Repparfjord Tectonic Window in northern Norway. The phyllonite hosting the vein formed at the expense of a metabasaltic protolith through feldspar breakdown to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the quartz vein acted as a relatively rigid body. Viscous deformation in the vein was initially accommodated by quartz basal slip. Under the prevailing deformation conditions, however, dislocation glide- and possibly creep-accommodated deformation of quartz was inefficient, and this resulted in localized strain hardening. In response to the (1) hardening, (2) progressive and cyclic increase of the fluid pressure, and (3) increasing competence contrast between the vein and the weakly foliated host phyllonite, vein quartz crystals began to deform by brittle processes along specific, suitably oriented lattice planes, creating microgouges along microfractures. Nucleated new grains rapidly sealed these fractures as fluids penetrated the actively deforming system. The grains grew initially by solution precipitation and later by grain boundary migration. We suggest that the different initial orientation of the vein crystals led to strain accommodation by different mechanisms in the individual crystals, generating remarkably different microstructures. Crystals suitably oriented for basal slip, for example, accommodated strain mainly viscously and experienced only minor fracturing. Instead, crystals

  19. Shock metamorphism of deformed quartz

    NASA Technical Reports Server (NTRS)

    Gratz, Andrew J.; Christie, John; Tyburczy, James; Ahrens, Thomas; Pongratz, Peter

    1988-01-01

    The effect produced by shock loading (to peak pressures of 12 and 24) on deformed synthetic quartz containing a dislocation and abundant bubbles and small inclusions was investigated, and the relationships between preexisting dislocation density shock lamellae in the target material were examined. The resultant material was found to be inhomogeneously deformed and extremely fractured. Results of TEM examinations indicate that no change in dislocation density was caused by shock loading except in regions containing shock lamellae, where the dislocation density was lowered. The shock-induced defects tend to nucleate on and be controlled by preexisting stress concentrators; shock lamellae, glassy veins, and most curviplanar defects form in tension, presumably during release. An extremely mobile silica fluid is formed and injected into fractures during release, which forcibly removes crystalline fragments from vein walls. It is concluded that shock deformation in quartz is dominated by fracture and melting.

  20. Triboluminescence of glasses and quartz

    NASA Astrophysics Data System (ADS)

    Chapman, G. N.; Walton, Alan J.

    1983-10-01

    The triboluminescent spectra of a variety of glasses and of crystalline quartz were measured while specimens were cut with a rotating diamond-impregnated saw blade. The spectra, which resemble the emission of a blackbody radiator, were recorded using an image-intensifier spectrograph. The data were intensity-corrected before being fitted to blackbody emission curves. Emission temperatures of around 1850 K for armor plate glass, 2100 K for Pyrex glass, 2400 K for soda lime glass, 2300 K for high-density lead glass, and 2800 K for cut quartz were obtained. It was found that the blackbody temperatures could be accounted for by a model in which a rectangular-shaped high-temperature zone, uniformly heated by energy released by plastic deformation near the crack tip, is supposed to propagate with the crack velocity [R. Weichert and K. Schonert, Q. J. Mech. Appl. Math. 31, 363-379 (1978)]. The measured blackbody temperatures imply zone widths of around 1×10-9 m. The spectrum from impact-fractured quartz was also measured; it was found to have a photoluminescent origin.

  1. Alkalis in Coal and Coal Cleaning Products / Alkalia W Węglu I Productach Jego Wzbogacania

    NASA Astrophysics Data System (ADS)

    Bytnar, Krzysztof; Burmistrz, Piotr

    2013-09-01

    In the coking process, the prevailing part of the alkalis contained in the coal charge goes to coke. The content of alkalis in coal (and also in coke) is determined mainly by the content of two elements: sodium and potasium. The presence of these elements in coal is connected with their occurrence in the mineral matter and moisture of coal. In the mineral matter and moisture of the coals used for the coke production determinable the content of sodium is 26.6 up to 62. per cent, whereas that of potassium is 37.1 up to 73.4 per cent of the total content of alkalis. Major carriers of alkalis are clay minerals. Occasionally alkalis are found in micas and feldspars. The fraction of alkalis contained in the moisture of the coal used for the production of coke in the total amount of alkalis contained there is 17.8 up to 62.0 per cent. The presence of sodium and potassium in the coal moisture is strictly connected with the presence of the chloride ions. The analysis of the water drained during process of the water-extracting from the flotoconcentrate showed that the Na to K mass ratio in the coal moisture is 20:1. Increased amount of the alkalis in the coal blends results in increased content of the alkalis in coke. This leads to the increase of the reactivity (CRI index), and to the decrease of strength (CSR index) determined with the Nippon Steel Co. method. W procesie koksowania przeważająca część zawartych we wsadzie węglowym alkaliów przechodzi do koksu. Zawartość alkaliów w węglu, a co za tym idzie i w koksie determinowana jest głównie zawartością dwóch pierwiastków: sodu i potasu. Obecność tych pierwiastków w węglu wiąże się z występowaniem ich w substancji mineralnej i wilgoci węgla. W substancji mineralnej oraz wilgoci węgli stosowanych do produkcji koksu, oznaczona zawartość sodu wynosi od 26.6 do 62.9%, a zawartość potasu od 37.1 do 73.4% alkaliów ogółem. Głównymi nośnikami alkaliów w substancji mineralnej są minera

  2. Experimental studies of alunite: II. Rates of alunite-water alkali and isotope exchange

    USGS Publications Warehouse

    Stoffregen, R.E.; Rye, R.O.; Wasserman, M.D.

    1994-01-01

    Rates of alkali exchange between alunite and water have been measured in hydrothermal experiments of 1 hour to 259 days duration at 150 to 400??C. Examination of run products by scanning electron microscope indicates that the reaction takes place by dissolution-reprecipitation. This exchange is modeled with an empirical rate equation which assumes a linear decrease in mineral surface area with percent exchange (f) and a linear dependence of the rate on the square root of the affinity for the alkali exchange reaction. This equation provides a good fit of the experimental data for f = 17% to 90% and yields log rate constants which range from -6.25 moles alkali m-2s-1 at 400??C to - 11.7 moles alkali m-2s-1 at 200??C. The variation in these rates with temperature is given by the equation log k* = -8.17(1000/T(K)) + 5.54 (r2 = 0.987) which yields an activation energy of 37.4 ?? 1.5 kcal/mol. For comparison, data from O'Neil and Taylor (1967) and Merigoux (1968) modeled with a pseudo-second-order rate expression give an activation energy of 36.1 ?? 2.9 kcal/mol for alkali-feldspar water Na-K exchange. In the absence of coupled alkali exchange, oxygen isotope exchange between alunite and water also occurs by dissolution-reprecipitation but rates are one to three orders of magnitude lower than those for alkali exchange. In fine-grained alunites, significant D-H exchange occurs by hydrogen diffusion at temperatures as low as 100??C. Computed hydrogen diffusion coefficients range from -15.7 to -17.3 cm2s-1 and suggest that the activation energy for hydrogen diffusion may be as low as 6 kcal/mol. These experiments indicate that rates of alkali exchange in the relatively coarse-grained alunites typical of hydrothermal ore deposits are insignificant, and support the reliability of K-Ar age data from such samples. However, the fine-grained alunites typical of low temperature settings may be susceptible to limited alkali exchange at surficial conditions which could cause

  3. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles primarily in the form of water soluble alkali metal formates by treating the particles with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of added carbon monoxide. During the treating process the water insoluble alkali metal compounds comprising the insoluble alkali metal residues are converted into water soluble alkali metal formates. The resultant aqueous solution containing water soluble alkali metal formates is then separated from the treated particles and any insoluble materials formed during the treatment process, and recycled to the gasification process where the alkali metal formates serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. This process permits increased recovery of alkali metal constituents, thereby decreasing the overall cost of the gasification process by reducing the amount of makeup alkali metal compounds necessary.

  4. Feldspar-Bearing Igneous Rocks at Gale: A ChemCam Campaign

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Fabre, C.; Toplis, M.; Wiens, R. C.; Gasnault, O.; Forni, O.; Mangold, N.

    2014-09-01

    We present the first in situ evidences of feldspar-rich rocks ranging from granodioritic and alkalin effusive rocks (trachy basalts and syenitic liquids). Implication for primitive noachain crust will be discussed.

  5. Authigenic potassium feldspar in Cambrian carbonates: Evidence of Alleghanian brine migration

    USGS Publications Warehouse

    Hearn, P.P., Jr.; Sutter, J.F.

    1985-01-01

    The shallow-water limestones and dolostones of the Conococheague Limestone (Upper Cambrian) of western Maryland contain large amounts of authigenic potassium feldspar. The presence of halite daughter crystals in breached fluid inclusions, low whole-rock ratios of chlorine to bromine, and thermochemical data suggest that the potassium feldspar formed at low temperature by the reaction of connate brines with intercalated siliciclastic debris. Analyses of argon age spectra indicate that the authigenic feldspar probably formed during Late Pennsylvanian to Early Permian time. These results may indicate mobilization and migration of connate brines brought about by Alleghanian folding. The widespread occurrence of authigenic potassium feldspar in Cambrian and Ordovician carbonate rocks throughout the Appalachians suggests that this may have occurred throughout the entire basin.

  6. Evidence for Coordination and Redox Changes of Iron in Shocked Feldspar from Synchrotron MicroXANES

    NASA Technical Reports Server (NTRS)

    Delaney, J. S.; Dyar, M. D.; Hoerz, F.; Johnson, J. R.

    2003-01-01

    Shock modification of feldspar has been documented and experimentally reproduced in many studies since the recognition of maskelynite in Shergotty. Experimentally shocked feldspar samples have been well studied using chemical and crystallographic techniques. The crystallographic, site-specific characterization of major and minor elements is less well documented. We present early x-ray absorption (XAS) spectral data for a suite of albitite samples that were experimentally shocked at pressures between 17 and 50 Gpa.

  7. [Study on the fine structure of K-feldspar of Qichun granite].

    PubMed

    Du, Deng-Wen; Hong, Han-Lie; Fan, Kan; Wang, Chao-Wen; Yin, Ke

    2013-03-01

    Fine structure of K-feldspar from the Qichun granite was investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), and inductively coupled plasma mass spectrometry methods to understand the evolution of the granitic magmatism and its correlation to molybdenite mineralization. The XRD results showed that K-feldspar of the potassic alteration veins has higher ordering index and triclinicity and is namely microcline with triclinic symmetry. K-feldspar of the early cretaceous granite has relatively lower ordering index and has widening [131] peak and is locally triclinic ordering. K-feldspar of the late cretaceous granite has lowest ordering index and sharp [131] peak and is honiogeneously monoclinic. The FTIR results showed that the IR spectra of the Qichun K-feldspar are similar to that of orthoclase reported by Farmer (1974). The 640 cm-1 absorption band increases while the 540 cm-' absorption band decreases with increase in K-feldspar ordering index, also, the 1,010 cm-1 absorption band separates into 1,010 and 1,046 cm-1 absorption bands, with a change in the band shape from widening to sharp outline. The ICP-MS results suggested that K-feldspar of the early cretaceous granite has relatively higher metal elements and rare earth elements, and the granite exhibits better mineralization background, K-feldspar of the potassic alteration veins has markedly lower Sr and Ba, indicating that the alteration fluid originated from the granitic magmatism, and hence, potassic alteration is a good indicator for molybdenite exploration. PMID:23705418

  8. Investigation of structural properties associated with alkali-silica reaction by means of macro- and micro-structural analysis

    SciTech Connect

    Mo Xiangyin . E-mail: moxiangyin@njnu.edu.cn; Fournier, Benoit

    2007-02-15

    Structural properties associated with alkali-silica reaction were systematically investigated by means of macro-structural accelerated mortar prism expansion levels testing, combined with micro-structural analysis. One part of this study is to determine the reactivity of the aggregate by means of accelerated mortar bar tests, and also to evaluate perlite aggregate constituents, especially the presence of deleterious components and find main causes of the alkali-silica reaction, which was based on the petrographic studies by optical microscope and the implication of X-ray diffraction on the aggregate. Results implied that the aggregate was highly alkali-silica reactive and the main micro-crystalline quartz-intermediate character and matrix that is mainly composed of chalcedony are potentially suitable for alkali-silica reaction. The other part is to study the long-term effect of lithium salts against alkali-silica reaction by testing accelerated mortar prism expansion levels. The macro-structural results were also consistent with the micro-structural mechanisms of alkali-silica reaction of mortar prisms containing this aggregate and the effect of chemical admixtures by means of the methods of scanning electron microscope-X-ray energy-dispersive spectroscopy and X-ray diffraction. It was indicated by these techniques that lithium salts, which were introduced into concrete containing reactive aggregate at the mixing stage, suppressed the alkali-silica reaction by producing non-expansive crystalline materials.

  9. Fluid Inclusion Study of Quartz Xenocrysts in Mafic Dykes from Kawant Area, Chhota Udaipur District, Gujarat, India

    NASA Astrophysics Data System (ADS)

    Randive, Kirtikumar; Hurai, Vratislav

    2015-09-01

    Unusual mafic dykes occur in the proximity of the Ambadongar Carbonatite Complex, Lower Narmada Valley, Gujarat, India. The dykes contain dense population of quartz xenocrysts within the basaltic matrix metasomatised by carbonate-rich fluids. Plagioclase feldspars, relict pyroxenes, chlorite, barite, rutile, magnetite, Fe-Ti oxides and glass were identified in the basaltic matrix. Quartz xenocrysts occur in various shapes and sizes and form an intricate growth pattern with carbonates. The xenocrysts are fractured and contain several types of primary and secondary, single phase and two-phase fluid inclusions. The two-phase inclusions are dominated by aqueous liquid, whereas the monophase inclusions are composed of carbonic gas and the aqueous inclusions homogenize to liquid between 226°C and 361°C. Majority of the inclusions are secondary in origin and are therefore unrelated to the crystallization of quartz. Moreover, the inclusions have mixed carbonic-aqueous compositions that inhibit their direct correlation with the crustal or mantle fluids. The composition of dilute CO2-rich fluids observed in the quartz xenocrysts appear similar to those exsolved during the final stages of evolution of the Amba Dongar carbonatites. However, the carbonates are devoid of fluid inclusions and therefore their genetic relation with the quartz xenocrysts cannot be established.

  10. Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

    NASA Astrophysics Data System (ADS)

    Omer, Muhamed F.; Friis, Henrik

    2014-03-01

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic studies showed that the silica cementation occurred in five successive phases which can be distinguished by their luminescence pattern. The precipitations of two phases have predated the major compaction process while the other phases are younger. The successive phases represent a sequence of changes in silica supply which were classified as very early and early, derived from dissolved biogenic silica that precipitated as opal/microquartz, possibly pre-compactional and of non-luminescent quartz overgrowth type. This was followed by phases whose silica supply derived from pressure solution of quartz, dissolution of feldspar, and hydrothermal fluids related to major thrust fault event. These successive quartz cement phases showed an increase in luminescence and the development of complicated zonation pattern in late-stage quartz cementation.

  11. Doubly rotated contoured quartz resonators.

    PubMed

    Sinha, B K

    2001-09-01

    Doubly rotated contoured quartz resonators are used in the design of temperature-compensated stable clocks and dual-mode sensors for simultaneous measurements of pressure and temperature. The design of these devices is facilitated by models that can predict frequency spectra associated with the three thickness modes and temperature and stress-induced frequency changes as a function of crystalline orientation. The Stevens-Tiersten technique for the analysis of the C-mode of a doubly rotated contoured quartz resonator is extended to include the other two thickness modes. Computational results for harmonic and anharmonic overtones of all three thickness modes of such resonators help in optimizing the radius of curvature of the contour and electrode shape for suppression of unwanted modes and prevention of activity dips. The temperature and stress-induced changes in thickness-mode resonator frequencies are calculated from a perturbation technique for small dynamic fields superposed on a static bias. The static bias refers to either a temperature or stress-induced static deformation of the resonator plate. Phenomenological models are also used for calculating the temperature and stress-induced changes in resonant frequencies as a function of crystalline orientation. Results for the SBTC-cut quartz plate with a spherical convex contour of 260 mm indicate that normal trapping occurs for the third (n = 3) and fifth (n = 5) harmonic of the A-mode, the fundamental (n = 1) and third (n = 3) harmonic of the B-mode, and the fundamental (n = 1) and fifth (n = 5) harmonic of the C-mode. PMID:11570746

  12. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

    DOEpatents

    Joshi, Ashok V.; Balagopal, Shekar; Pendelton, Justin

    2011-12-13

    Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

  13. The calcium-alkali syndrome.

    PubMed

    Arroyo, Mariangeli; Fenves, Andrew Z; Emmett, Michael

    2013-04-01

    The milk-alkali syndrome was a common cause of hypercalcemia, metabolic alkalosis, and renal failure in the early 20th century. It was caused by the ingestion of large quantities of milk and absorbable alkali to treat peptic ulcer disease. The syndrome virtually vanished after introduction of histamine-2 blockers and proton pump inhibitors. More recently, a similar condition called the calcium-alkali syndrome has emerged as a common cause of hypercalcemia and alkalosis. It is usually caused by the ingestion of large amounts of calcium carbonate salts to prevent or treat osteoporosis and dyspepsia. We describe a 78-year-old woman who presented with weakness, malaise, and confusion. She was found to have hypercalcemia, acute renal failure, and metabolic alkalosis. Upon further questioning, she reported use of large amounts of calcium carbonate tablets to treat recent heartburn symptoms. Calcium supplements were discontinued, and she was treated with intravenous normal saline. After 5 days, the calcium and bicarbonate levels normalized and renal function returned to baseline. In this article, we review the pathogenesis of the calcium-alkali syndrome as well as the differences between the traditional and modern syndromes. PMID:23543983

  14. Metasomatism, titanian acmite, and alkali amphiboles in lithic- wacke inclusions within the Coyote Peak diatreme, Humboldt County, California.

    USGS Publications Warehouse

    Czamanske, S.A.; Atkin, G.K.

    1985-01-01

    Lithic-wacke inclusions within the alkali-ultramafic diatreme at Coyote Peak record a history of pronounced metasomatism and crystal growth. The dominant metasomatic changes were loss of Si from the inclusions and mass influx of K, due to an unusually high K activity in the ultramafic host. The reaction with K converted much of the clay, quartz and lithic fraction of the lithic wacke into microcline, and exchanged Na from abundant clastic albite. Probe analyses are tabulated for cores and rims of titanian acmites, augites and alkali amphiboles. -J.A.Z.

  15. Anisotropy in Experimentally Compressed Kaolinite-Illite-Quartz Aggregates: Microstructure, Preferred Orientation and Acoustic Velocities

    NASA Astrophysics Data System (ADS)

    Voltolini, M.; Wenk, H.; Mondol, N. H.; Bjørlykke, K.; Jahren, J.

    2007-12-01

    Shales and mudstones composed of clay minerals and quartz are important sedimentary rocks that frequently display anisotropy of physical properties. This study investigates anisotropy in experimentally compressed kaolinite-illite-quartz aggregates by determining preferred orientation (texture) of component phases and comparing results with acoustic anisotropy. Sample were prepared compressing clay (81% kaolinite, 14% illite and 4% K-feldspar)-silt (~99% quartz) mixtures (0 to 100% clay) at 5 and 50 MPa vertical effective stress to explore the role of clay content and compaction stress on the elastic properties. Optical and scanning electron microscopy have been used to characterize microstructures. Texture patterns are quantified based on synchrotron X-ray diffraction patterns analyzed with the Rietveld method. Preferred orientation of quartz is more or less random. Clay minerals are strongly oriented. Pole figures display axisymmetric (001) maxima parallel to the compression direction, ranging in strength from 1.6 to 8 multiples of a random distribution. Texture strength strongly increases with compaction pressure and clay content. Both microstructure and preferred orientation are essential contributions to aggregate elastic properties that have been calculated by averaging single crystal properties over the orientation distributions. Calculated P-wave velocity anisotropies range from 0% (100% quartz) to 44% (100% clay, 50 MPa). Anisotropy roughly doubles by increasing the vertical effective stress from 5 to 50 MPa. In experiments only P- and S-wave velocities parallel to the compression direction were measured and values (2-3 km/s) are much lower than those predicted by single crystal averaging (5-7 km/s) which we attribute mainly to the influence of porosity that was not considered in the model. With these experimental compaction data we are currently refining a model to determine macroscopic properties of mudstones and shales based on detailed information of

  16. Nature and origin of authigenic K-feldspar in Precambrian basement rocks of the North American midcontinent

    SciTech Connect

    Duffin, M.E. )

    1989-08-01

    Authigenic K-feldspar occurs in alteration profiles in uppermost Precambrian igneous and metamorphic basement rocks of the midcontinent. The K-feldspar is widespread and has been identified in six states. The profiles occur directly below the Cambrian-Precambrian unconformity and range from about <1 to 8 m in thickness. Authigenic K-feldspar occurs throughout the profile. The K-feldspar is monoclinic or triclinic by X-ray diffraction, of end-member composition, and may compose 63% of rock volume. Much of the K-feldspar formed by replacement of primary feldspar. A sample of wholly authigenic K-feldspar from altered basement in southern Illinois gives a K/Ar data of 549 {plus minus} 18 Ma (Early Cambrian). This data is in agreement with Early Cambrian Rb/Sr dates for potassic alteration of uppermost Precambrian basement in Ohio. Dated authigenic K-feldspars from both Ohio and Illinois give identical {delta}{sup 18}O values of 17.5, suggesting formation from a very similar fluid. Concordancy of both dates and {delta}{sup 18}O values suggests that the K-feldspar formed during an episode of potassic alteration during Early Cambrian time that affected much of midcontinent North America. The dates and {delta}{sup 18}O values for K-feldspar, when considered together, do not fit any of the hypotheses presented here.

  17. Impact polymorphs of quartz: experiments and modelling

    NASA Astrophysics Data System (ADS)

    Price, M. C.; Dutta, R.; Burchell, M. J.; Cole, M. J.

    2013-09-01

    We have used the light gas gun at the University of Kent to perform a series of impact experiments firing quartz projectiles onto metal, quartz and sapphire targets. The aim is to quantify the amount of any high pressure quartz polymorphs produced, and use these data to develop our hydrocode modelling to enable the predict ion of the quantity of polymorphs produced during a planetary scale impact.

  18. New observations on the quartz monzodiorite-granite suite. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Marvin, U. B.; Holmberg, B. B.; Lindstrom, M. M.; Martinez, R. R.

    1991-01-01

    Five new fragments of quartz monzodiorite (QMD) were identified in particles from soil 15403, which was collected from the boulder sampled as rock 15405, an impact-melt breccia containing clasts of KREEP basalt, QMD, granite, and a more primitive alkali norite. Petrographic and geochemical studies of the fragments show considerable variation in modal proportions and bulk composition. This heterogeneity is due to unrepresentative sampling in small fragments of coarse-grained rocks. Variations in the proportions of accessory minerals have marked effects on incompatible-trace-element concentrations and ratios. Semiquantitative calculations support the derivation of QMD from 60-percent fractional crystallization of a KREEP basalt magma as suggested by Hess (1989). Apollo 15 KREEP basalt cannot be the actual parent magma because the evolved rocks predate volcanic KREEP basalts. It is suggested that ancient KREEP basalt magmas have crystallized as plutons, with alkali norite clasts offering the only direct evidence of this precursor.

  19. A Single-Crystalline Mesoporous Quartz Superlattice.

    PubMed

    Matsuno, Takamichi; Kuroda, Yoshiyuki; Kitahara, Masaki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2016-05-10

    There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li(+) only on the surface of silica nanospheres is effective for crystallization. PMID:27060365

  20. Progress in Understanding Alkali-Alkali Spin Relaxation

    NASA Astrophysics Data System (ADS)

    Erickson, Christopher J.; Happer, William; Chann, Bien; Kadlecek, Stephen; Anderson, L. W.; Walker, Thad G.

    2000-06-01

    In extensive experiments we have shown that a spin interaction with a relatively long correlation time causes much of the spin relaxation in very dense alkali-metal vapors. The spin relaxation is affected by the pressure of the helium or nitrogen buffer gas, although there is little dependence at pressures above one atmosphere. There are substantial differences in the relaxation rates for different isotopes of the same element, for example ^87Rb and ^85Rb. We have completed extensive modeling of how singlet and triplet dimers and doublet trimers of the alkali-metal atoms could cause spin relaxation in dense alkali-metal vapors. In the case of doublet trimers or triplet dimers, we assume the main coupling to the nuclear spins is through the Fermi Contact interaction with the unpaired electrons. Spin loss to the rotation of the molecule is assumed to occur through the electronic spin-rotation and spin-axis (dipole-dipole) interactions for the triplet dimers. For the singlet dimers, we assume that the nuclear spins couple directly to the rotational angular momentum of the molecule through the electric quadrupole interaction. We account for all of the total nuclear spin states that occur for the dimers and trimers. We have also considered the possibility that the collisional breakup and formation rates of the dimers or trimers could saturate with increasing buffer gas pressure. Such saturation occurs in many other unimolecular reactions and is often ascribed to breakup through activated states.

  1. Solubility of Albite + Paragonite +/- Quartz in H2O at 1 GPa, 580° C: Implications for Metamorphic Fluids

    NASA Astrophysics Data System (ADS)

    Antignano, A.; Manning, C.

    2003-12-01

    One of the most common mineral assemblages in crustal metamorphism is feldspar + quartz; however, little is known about the solubility of this assemblage in metamorphic fluids. We measured the solubility of albite and albite+quartz in H2O at 580° C and 1.0 GPa using a piston cylinder apparatus. Experiments were conducted using Amelia albite in NaCl-graphite assemblies. Experiments were conducted using a double capsule arrangement. Inner capsules consisting of perforated 1.6 mm OD Pt capsules containing a single albite crystal were load in 3.5mm OD outer capsules containing ultra pure H2O +/- quartz. Solubility was determined by the weight loss of single albite and quartz grains after 8 hr runs. Time series experiments on this system show no variation in fluid composition or solubility after 4hrs. Albite exhibited incongruent dissolution, yielding paragonite as a husk that mantles the albite grain. The composition of the fluid was determined by mass balance as determined by the weights of albite, quartz, and paragonite. In the albite-only experiments, the concentration of total dissolved solids (TDS) were 0.628 molal, with Na, Al and Si in the fluid of 0.137, 0.081, and 0.41 molal, respectively, and Na/Al of 1.691. In the presence of quartz, there is an increase in the overall TDS to 0.777 molal. Albite-quartz experiments produce an increase in Si concentration to 0.628 molal, with lower Na and Al concentrations of 0.098 and 0.051 molal, respectively, and Na/Al of 1.922. The aqueous Si concentrations in the albite-only experiments are higher than those in fluid equilibrated with quartz (Manning, 1994, GCA, 58, 4831) at the same conditions. This is consistent with the data of Anderson and Burnham (1983, Am. J. Sci., 283-A, 283) on albite. In the quartz-present experiments results show still higher Si concentration in the fluid phase. Our results demonstrate enhanced solubility of silica in the presence of albite and albite+quartz, relative to quartz alone

  2. Rock-Forming feldspars of the Khibiny alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Konopleva, N. G.; Kalashnikov, A. O.; Korchak, Yu. A.; Selivanova, E. A.; Yakovenchuk, V. N.

    2010-12-01

    This paper describes the structural-compositional zoning of the well-known Khibiny pluton in regard to rock-forming feldspars. The content of K-Na-feldspars increases inward and outward from the Main foidolite ring. The degree of coorientation of tabular K-Na-feldspar crystals sharply increases in the Main ring zone, and microcline-dominant foyaite turns into orthoclase-dominant foyaite. The composition of K-Na-feldspars in the center of the pluton and the Main ring zone is characterized by an enrichment in Al. This shift is compensated by a substitution of some K and Na with Ba (the Main ring zone) or by an addition of K and Na cations to the initially cation-deficient microcline (the central part of the pluton). Feldspars of volcanosedimentary rocks occurring as xenoliths in foyaite primarily corresponded to plagioclase An15-40, but high-temperature fenitization and formation of hornfels in the Main ring zone gave rise to the crystallization of anorthoclase subsequently transformed into orthoclase and albite due to cooling and further fenitization. Such a zoning is the result of filling the Main ring fault zone within the homogeneous foyaite pluton with a foidolite melt, which provided the heating and potassium metasomatism of foyaite and xenoliths of volcanosedimentary rocks therein. The process eventually led to the transformation of foyaite into rischorrite-lyavochorrite, while xenoliths were transformed into aluminum hornfels with anorthoclase, annite, andalusite, topaz, and sekaninaite.

  3. Asbestos contamination in feldspar extraction sites: a failure of prevention? Commentary.

    PubMed

    Cavariani, Fulvio

    2016-01-01

    Fibrous tremolite is a mineral species belonging to the amphibole group. It is present almost everywhere in the world as a natural contaminant of other minerals, like talc and vermiculite. It can be also found as a natural contaminant of the chrysotile form of asbestos. Tremolite asbestos exposures result in respiratory health consequences similar to the other forms of asbestos exposure, including lung cancer and mesothelioma. Although abundantly distributed on the earth's surface, tremolite is only rarely present in significant deposits and it has had little commercial use. Significant presence of amphibole asbestos fibers, characterized as tremolite, was identified in mineral powders coming from the milling of feldspar rocks extracted from a Sardinian mining site (Italy). This evidence raises several problems, in particular the prevention of carcinogenic risks for the workers. Feldspar is widespread all over the world and every year it is produced in large quantities and it is used for several productive processes in many manufacturing industries (over 21 million tons of feldspar mined and marketed every year). Until now the presence of tremolite asbestos in feldspar has not been described, nor has the possibility of such a health hazard for workers involved in mining, milling and handling of rocks from feldspar ores been appreciated. Therefore the need for a wider dissemination of knowledge of these problems among professionals, in particular mineralogists and industrial hygienists, must be emphasized. In fact both disciplines are necessary to plan appropriate environmental controls and adequate protections in order to achieve safe working conditions. PMID:27033611

  4. Positron-alkali atom scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.; Ward, S. J.

    1990-01-01

    Positron-alkali atom scattering was recently investigated both theoretically and experimentally in the energy range from a few eV up to 100 eV. On the theoretical side calculations of the integrated elastic and excitation cross sections as well as total cross sections for Li, Na and K were based upon either the close-coupling method or the modified Glauber approximation. These theoretical results are in good agreement with experimental measurements of the total cross section for both Na and K. Resonance structures were also found in the L = 0, 1 and 2 partial waves for positron scattering from the alkalis. The structure of these resonances appears to be quite complex and, as expected, they occur in conjunction with the atomic excitation thresholds. Currently both theoretical and experimental work is in progress on positron-Rb scattering in the same energy range.

  5. Alkali metal/sulfur battery

    DOEpatents

    Anand, Joginder N.

    1978-01-01

    Alkali metal/sulfur batteries in which the electrolyte-separator is a relatively fragile membrane are improved by providing means for separating the molten sulfur/sulfide catholyte from contact with the membrane prior to cooling the cell to temperatures at which the catholyte will solidify. If the catholyte is permitted to solidify while in contact with the membrane, the latter may be damaged. The improvement permits such batteries to be prefilled with catholyte and shipped, at ordinary temperatures.

  6. Superconductivity in alkali metal fullerides

    NASA Astrophysics Data System (ADS)

    Murphy, D. W.; Rosseinsky, M. J.; Haddon, R. C.; Ramirez, A. P.; Hebard, A. F.; Tycko, R.; Fleming, R. M.; Dabbagh, G.

    1991-12-01

    The recent synthesis of macroscopic quantities of spherical molecular carbon compounds, commonly called fullerenes, has stimulated a wide variety of studies of the chemical and physical properties of this novel class of compounds. We discovered that the smallest of the known fullerenes, C 60, could be made conducting and superconducting by reaction with alkali metals. In this paper, an overview of the motivation for these discoveries and some recent results are presented.

  7. Alkali metal sources for OLED devices

    NASA Astrophysics Data System (ADS)

    Cattaneo, Lorena; Longoni, Giorgio; Bonucci, Antonio; Tominetti, Stefano

    2005-07-01

    In OLED organic layers electron injection is improved by using alkali metals as cathodes, to lower work function or, as dopants of organic layer at cathode interface. The creation of an alkali metal layer can be accomplished through conventional physical vapor deposition from a heated dispenser. However alkali metals are very reactive and must be handled in inert atmosphere all through the entire process. If a contamination takes place, it reduces the lithium deposition rate and also the lithium total yield in a not controlled way. An innovative alkali metal dispensing technology has been developed to overcome these problems and ensure OLED alkali metal cathode reliability. The alkali Metal dispenser, called Alkamax, will be able to release up to a few grams of alkali metals (in particular Li and Cs) throughout the adoption of a very stable form of the alkali metal. Lithium, for example, can be evaporated "on demand": the evaporation could be stopped and re-activated without losing alkali metal yield because the metal not yet consumed remains in its stable form. A full characterization of dispensing material, dispenser configuration and dispensing process has been carried out in order to optimize the evaporation and deposition dynamics of alkali metals layers. The study has been performed applying also inside developed simulations tools.

  8. Sealed-in-quartz resistance heater

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Stephens, J. B.

    1980-01-01

    Electric resistance quartz heater operates at 1,400 F without developing excessively hot spots that can fail prematurely. Since resistance element is sealed in quartz, heater can be used in hostile environments. Sealed construction also keeps heater from contaminating heated object.

  9. Precise Sealing of Fused-Quartz Ampoules

    NASA Technical Reports Server (NTRS)

    Debnan, W. J. J.; Clark, I. O.

    1982-01-01

    New technique rapidly evacuates and seals fused-quartz ampoule with precise clearance over contents without appreciably thinning ampoule walls. Quartz plug is lowered into working section of ampoule after ampoule has been evacuated. Plug is then fused to ampoule walls, forming vacuum seal. New technique maintains wall strength and pumping speed.

  10. The Quartz Analog Watch: A Wonder Machine.

    ERIC Educational Resources Information Center

    Crane, H. Richard, Ed.

    1993-01-01

    Summarizes how a quartz watch works. Discusses the quartz crystal, its form, and how its frequency is set to a standard; the integrated circuit chip that drives the crystal in vibration, scales its frequency down, and forms pulses that turn the motor; and the motor that drives the gear train that turns the hands. (ZWH)

  11. Regional and local correlations of feldspar geochemistry of the Peach Spring Tuff, Alvord Mountain, California

    USGS Publications Warehouse

    Buesch, David C.

    2016-01-01

    The chemical composition of feldspar grains in an ignimbrite from the Spanish Canyon Formation in the Alvord Mountain area, California, have been used to confirm similarities in three measured sections locally, and they are similar to exposures of the Peach Spring Tuff (PST) regionally. Feldspar grains were identified on the basis of texture (zoning, as mantled feldspars, or in crystal clusters), whether the grains were attached to glass or were in pumice clasts, or were simply crystal fragments with no textural context. Chemistry was determined by electron microprobe analysis, and each analysis is calculated in terms of the percent endmember and plotted on orthoclase (Or) versus anorthite (An) plots. In general, the PST has sanidine and plagioclase compositions that are consistent with having formed in high-silica rhyolite and trachyte within a zoned magma chamber. Feldspars from the PST in Spanish Canyon area cluster along the rhyolitic trend with no grains along the trachytic trend. Similar clustering of feldspars along the rhyolitic trend with no grains along the trachytic trend also occur in the PST from Granite Spring and Providence Mountains to the east of the Alvord Mountain area, and the ranges in compositions are also similar in these locations. In contrast, the PST in the Kane Wash area of the Newberry Mountains has feldspars only from the rhyolitic trend in the basal deposits, but some grains from the trachytic trend are in the upper part of the deposit, and the range in compositions are greater than in the Spanish Canyon area. The variations in vertical compositional zoning and compositional range in these different deposits suggests there were probably different flow paths (or timing of the delivery) during the eruption and runout of the pyroclastic flow(s) generated from the climactic eruption of the PST magma chamber.

  12. Quartz gauge response in ion radiation

    NASA Astrophysics Data System (ADS)

    Taylor, P. E.; Gilbert, P. H.; Kernthaler, C.; Lee, L. M.; Smith, E. A.; Reeder, S. T.; Anderson, M. U.

    1996-05-01

    This paper describes recent work to make high quality quartz gauge (temporal and spatial) shock wave measurements in a pulsed ion beam environment. Intense ion beam radiation, nominally 1 MeV protons, was deposited into material samples instrumented with shunted quartz gauges adjacent to the ion deposition zone. Fluence levels were chosen to excite three fundamentally different material response modes (1) strong vapor, (2) combined vapor and melt phase and (3) thermoelastic material response. A unique quartz gauge design was utilized that employed printed circuit board (PCB) technology to facilitate electrical shielding, ruggedness, and fabrication while meeting the essential one dimensional requirements of the characterized Sandia shunted quartz gauge. Shock loading and unloading experiments were conducted to evaluate the piezoelectric response of the coupled quartz gauge/PCB transducer. High fidelity shock wave profiles were recorded at the three ion fluence levels providing dynamic material response data for vapor, melt and solid material phases.

  13. Quartz gauge response in ion radiation

    SciTech Connect

    Taylor, P.E.; Gilbert, P.H.; Kernthaler, C.; Lee, L.M.; Smith, E.A.; Reeder, S.T.; Anderson, M.U.

    1995-12-31

    This paper describes recent work to make high quality quartz gauge (temporal and spatial) shock wave measurements in a pulsed ion beam environment. Intense ion beam radiation, nominally 1 MeV protons, was deposited into material samples instrumented with shunted quartz gauges adjacent to the ion deposition zone. Fluence levels were chosen to excite three fundamentally different material response modes (1) strong vapor, (2) combined vapor and melt phase and (3) thermoelastic material response. A unique quartz gauge design was utilized that employed printed circuit board (PCB) technology to facilitate electrical shielding, ruggedness, and fabrication @e meeting the essential one dimensional requirements of the characterized Sandia shunted quartz gauge. Shock loading and unloading experiments were conducted to evaluate the piezoelectric response of the coupled quartz gauge/PCB transducer. High fidelity shock wave profiles were recorded at the three ion fluence levels providing dynamic material response data for vapor, melt and solid material phases.

  14. Deformation of the deep crust: Insights from physiochemical characteristics of deformation microstructures of plagioclase and quartz in gneiss from the Salt Mylonite Zone, Western Gneiss Region, Norway

    NASA Astrophysics Data System (ADS)

    Renedo, R. N.; Piazolo, S.; Whitney, D. L.; Teyssier, C. P.

    2014-12-01

    The deformation behavior of quartz and feldspar controls the rheology of large parts of the continental crust. One way to understand the deformation of these abundant and important minerals in the deep crust is to compare their behavior within and outside of naturally-deformed shear zones. To this end, three samples of quartzofeldspathic gneiss within and adjacent to the Salt Mylonite Zone, a discrete ductile deformation zone in the ultrahigh-pressure Western Gneiss Region of Norway, are investigated in terms of microstructure, chemical composition, and fabric. The three samples represent the microstructural variation across the shear zone including grain size variation, layered (quartz ribbon bearing) v. non-layered gneiss, and variation in modal abundance. Layered gneiss is composed of one grain thick, laterally continuous quartz ribbons with plagioclase and accessory phases in the intervening regions. Non-layered gneiss consists of isolated quartz (individual grains or clusters of up to four grains) within an interconnected network of plagioclase and accessory phases. In layered gneiss, quartz preserves a well-developed crystallographic preferred orientation consistent with dominant activation of the prism and rhomb slip systems, and plagioclase preserves a nearly random fabric. Quartz fabrics from layered shear zone gneiss are stronger than those of quartz from layered gneiss outside of the shear zone. In non-layered gneiss, plagioclase develops a fabric that is consistent with activation of the (001) <010> slip system whereas quartz exhibits a random fabric. Plagioclase in all samples is zoned from Na-richer cores to Ca-richer rims (reverse zoning); zoning is weaker outside of the shear zone (average core-to-rim ΔAn 6%) than within the shear zone (average core-to-rim ΔAn 10%). Results suggest a change in plagioclase and quartz deformation mechanisms occurred during decompression and shear zone development owing to strain/strain-rate variation.

  15. Ti distribution in quartz across a heterogeneous shear zone within a granodiorite: the effect of deformation mechanism and strain on Ti resetting

    NASA Astrophysics Data System (ADS)

    Bestmann, Michel; Pennacchioni, Giorgio

    2015-04-01

    The study of a heterogeneous ductile shear zone developed at ca. 500 °C and 0.2 GPa during post-magmatic cooling of a granodiorite allows the effect of strain and recrystallization on Ti re-equilibration of quartz to be assessed. Understanding this effect is critical for applying Ti-in-quartz (TitaniQ) thermobarometry to mylonites. Differently strained quartz across the shear zone shows a heterogeneous distribution of Ti (measured by SIMS) with overall Ti range between 2 and 45 ppm. Quartz cathodoluminescence (CL) is proved by spectral analysis to be univocally correlated to Ti content and CL images were calibrated as Ti maps using SIMS measurements. Coarse grained weakly deformed domains consist of magmatic quartz extensively recrystallized by grain boundary migration (GBM) and mostly (65-75% area) contain 20-38 ppm Ti. Ti resetting to lower amounts occurred locally: (i) in haloes surrounding titanite and biotite inclusions (Ti as low as 6 ppm); (ii) along grain boundaries and healed microfractures; and (iii) towards the quartz domain boundary. With increasing strain quartz underwent progressive grainsize reduction and developed a bimodal microstructure with elongate grains (>100's µm long) surrounded by mantles of new grains (10-30 µm in size) recrystallized by subgrain rotation (SR). Dynamic recrystallization by SGR, associated with prism slip, became increasingly important over GBM as strain increased towards the shear zone core. Relevant resetting of Ti in quartz only occurred in high strain domains (shear strain gamma ≥ 10) in the shear zone core where fine recrystallization amounts at 50-60% area and coarser cores are strongly substructured. These domains are not compositionally homogeneous and still show a range of Ti content between 2 and 10 ppm. In all strain facies of the shear zone quartz-filled pressure shadows associated with feldspar show an almost constant Ti of ~ 2ppm. Therefore the pristine Ti content of the magmatic quartz mylonitized in

  16. Isothermal thermoluminescence dating of K-feldspar from sediments to determine fault slip rates: development and assessment

    NASA Astrophysics Data System (ADS)

    Rhodes, E. J.; Roder, B. J.; Lawson, M. J.; Dolan, J. F.; McGill, S. F.; McAuliffe, L.

    2012-04-01

    Faults in California accommodate most of the relative motion between the Pacific and North American tectonic plates, along either one main strike-slip fault, - the San Andreas fault - or a network of sub-parallel faults (e.g., the San Jacinto, Elsinore and San Andreas faults). Slip is also accommodated along many other associated faults and folds, and the region suffers frequent damaging earthquakes. Contemporary movements of different fault-bounded blocks are relatively well established on decadal timescales using remote sensing and GPS, and on timescales of 106 to 107 years, by dating offset geologic features with radiometric methods. However, on timescales of decades to several hundred thousand years, determining total fault offset and mean slip rate is harder. Critical questions for understanding fault dynamics and improving earthquake risk assessment include the degree to which slip is clustered into episodes of more rapid movement, and how slip is accommodated by different sub-parallel faults. In many cases, streams with offset courses can be recognised, and in some cases offset terrace surfaces can be located, especially when using LiDAR data to complement field mapping. Radiocarbon and terrestrial cosmogenic nuclides have been used to date these features, but both have limitations of age range, sample suitability and availability. OSL (optically stimulated luminescence) and IRSL (infra-red stimulated luminescence) have great potential to complement these techniques, though the characteristics of quartz in some parts of southern California are suboptimal, displaying low sensitivity and other limitations. In order to overcome these limitations encountered using quartz OSL, we are developing a new geochronometer based on the isothermal thermoluminescence (ITL) signal of K feldspar measured at 250°C. Preliminary ITL age estimates from the paleoseismic site of El Paso Peaks on the Central Garlock fault in the Mojave Desert, California, agree well with a well

  17. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  18. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  19. Geology of the Quartz Creek Pegmatite District, Gunnison County Colorado

    USGS Publications Warehouse

    Staatz, Mortimer H.; Trites, A.F.

    1952-01-01

    Inferred reserves of the district are estimated for beryl, scrap mica, both hand-cobbing and milling feldspar, lepidolite, columbite-tantalite, topaz, monazite, and microlite. No sheet mica was found. Reserves are small and transportation costs are high so substantial production of low-priced feldspar and scrap mica will depend on the adoption of economica milling techniques for recovering the large quantities of feldspar available.  Beryl is irregularly distributed and its recovery as a byproduct will depend on the establishment of a stable market for feldspar and scrap mica.  Lepidolite reserves are small low grade.

  20. Alkali-Activated Aluminium-Silicate Composites as Insulation Materials for Industrial Application

    NASA Astrophysics Data System (ADS)

    Dembovska, L.; Bajare, D.; Pundiene, I.; Bumanis, G.

    2015-11-01

    The article reports on the study of thermal stability of alkali-activated aluminium- silicate composites (ASC) at temperature 800-1100°C. ASC were prepared by using calcined kaolinite clay, aluminium scrap recycling waste, lead-silicate glass waste and quartz sand. As alkali activator, commercial sodium silicate solution modified with an addition of sodium hydroxide was used. The obtained alkali activation solution had silica modulus Ms=1.67. Components of aluminium scrap recycling waste (aluminium nitride (AlN) and iron sulphite (FeSO3)) react in the alkali media and create gases - ammonia and sulphur dioxide, which provide the porous structure of the material [1]. Changes in the chemical composition of ASC during heating were identified and quantitatively analysed by using DTA/TG, dimension changes during the heating process were determined by using HTOM, pore microstructure was examined by SEM, and mineralogical composition of ASC was determined by XRD. The density of ASC was measured in accordance with EN 1097-7. ASC with density around 560 kg/m3 and heat resistance up to 1100°C with shrinkage less than 5% were obtained. The intended use of this material is the application as an insulation material for industrial purposes at elevated temperatures.

  1. Alkali-Metal Spin Maser.

    PubMed

    Chalupczak, W; Josephs-Franks, P

    2015-07-17

    Quantum measurement is a combination of a read-out and a perturbation of the quantum system. We explore the nonlinear spin dynamics generated by a linearly polarized probe beam in a continuous measurement of the collective spin state in a thermal alkali-metal atomic sample. We demonstrate that the probe-beam-driven perturbation leads, in the presence of indirect pumping, to complete polarization of the sample and macroscopic coherent spin oscillations. As a consequence of the former we report observation of spectral profiles free from collisional broadening. Nonlinear dynamics is studied through exploring its effect on radio frequency as well as spin noise spectra. PMID:26230788

  2. Quartz structure transformation under a shock wave

    NASA Astrophysics Data System (ADS)

    Vettegren', V. I.; Kuksenko, V. S.; Shcherbakov, I. P.; Mamalimov, R. I.

    2015-12-01

    The structure of a fragment formed after quartz single-crystal fracture under a shock wave has been studied using the Fourier transform infrared spectroscopy (FTIR) method. The wave is initiated by electrical breakdown of air in a hole within the single crystal. It has been found that a layer ~0.15 μm thick consisting of "diaplectic glass," i.e., quartz with a strongly distorted lattice, is formed on the fragment surface. A layer 2 μm thick with a compressed quartz lattice is located under it.

  3. SCR neon and argon in Kapoeta feldspar: Evidence for an active ancient Sun

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Garrison, D. H.; Bogard, D. D.

    1993-01-01

    From etched feldspar size-fractions of Kapoeta, we determine a significant excess of cosmogenic Ne-21 and Ar-38 over that produced by galactic cosmic rays. This excess component is attributed to early production by energetic solar protons and suggest that the energetic proton flux from the ancient Sun was several hundred times more intense than that of the contemporary Sun.

  4. Re-Examination of Anomalous I-Xe Ages: Orgueil and Murchison Magnetites and Allegan Feldspar

    NASA Technical Reports Server (NTRS)

    Hohenberg, Charles M.; Pravdivtseva, Olga V.; Meshik, Alex P.

    2000-01-01

    Old I-Xe age for Orgueil (and Murchison) magnetite is not confirmed. New results show closure 2.8 Ma after Shallowater/Bjurbole standard, 10.3 Ma later than previously reported. The anomalously old I-Xe age of Allegan feldspar is attributed to shock.

  5. I-Xe Record of Cooling in K-Feldspar Inclusion from the Colomera (IIE) Iron

    NASA Technical Reports Server (NTRS)

    Pravdivtseva, Olga; Meshik, Alex; Hohenberg, Charles M.; Wasserburg, Gerald J.

    2000-01-01

    Individual mineral grains from a silicate inclusion of the Colomera IIE iron meteorite were studied by laser extraction to find suitable host phases for I-Xe dating. K-feldspar separate yields an I-Xe age of 4.552 Ga and a cooling rate of 4-16 C/Ma.

  6. Ti distribution in quartz across a heterogeneous shear zone within a granodiorite: The effect of deformation mechanism and strain on Ti resetting

    NASA Astrophysics Data System (ADS)

    Bestmann, Michel; Pennacchioni, Giorgio

    2015-06-01

    The study of a heterogeneous ductile shear zone that developed at ~ 500 °C and 0.2 GPa during post-magmatic cooling of a granodiorite has allowed the effect of strain and recrystallization on Ti re-equilibration of quartz to be assessed. Understanding this effect is critical for applying Ti-in-quartz thermobarometry to mylonites. Differently strained quartz across the shear zone shows a heterogeneous distribution of Ti concentrations ([Ti]) (measured by Secondary Ion Mass Spectrometry, SIMS) ranging between 2 and 45 ppm. Quartz cathodoluminescence (CL) is proven by spectral analysis to be correlated with [Ti], allowing CL images to be calibrated as Ti maps using SIMS measurements. Coarse-grained weakly deformed domains consist of magmatic quartz extensively recrystallized by grain boundary migration (GBM) and mostly (65-75% area) contain 20-38 ppm Ti. Resetting to lower [Ti] occurred locally: (i) in haloes surrounding titanite and biotite inclusions ([Ti] as low as 6 ppm); (ii) along grain boundaries; and (iii) towards the interface of quartz domains with other mineral domains. With increasing strain, quartz underwent progressive grain size reduction and developed a bimodal microstructure with elongate grains (> 100's μm long) surrounded by mantles of new grains (10-30 μm in size) recrystallized by subgrain rotation (SGR). Dynamic recrystallization by SGR, associated with prism < a > slip, became increasingly dominant over GBM as strain increased towards the shear zone core. Significant resetting of Ti in quartz only occurred in high strain domains (at shear strain γ probably >> 10) in the shear zone core where fine recrystallization amounts to 50-60% by area and coarser cores are strongly sub-structured. These domains are not compositionally homogeneous and still show a range of [Ti] mostly between 2 and 10 ppm. In all strain facies of the shear zone quartz-filled pressure shadows associated with feldspar show an almost constant [Ti] of ~ 2 ppm. The pristine

  7. Mineral dissolution in the Cape Cod aquifer, Massachusetts, USA: I . Reaction stoichiometry and impact of accessory feldspar and glauconite on strontium isotopes, solute concentrations, and REY distribution

    NASA Astrophysics Data System (ADS)

    Bau, Michael; Alexander, Brian; Chesley, John T.; Dulski, Peter; Brantley, Susan L.

    2004-03-01

    To compare relative reaction rates of mineral dissolution in a mineralogically simple groundwater aquifer, we studied the controls on solute concentrations, Sr isotopes, and rare earth element and yttrium (REY) systematics in the Cape Cod aquifer. This aquifer comprises mostly carbonate-free Pleistocene sediments that are about 90% quartz with minor K-feldspar, plagioclase, glauconite, and Fe-oxides. Silica concentrations and pH in the groundwater increase systematically with increasing depth, while Sr isotopic ratios decrease. No clear relationship between 87Sr/ 86Sr and Sr concentration is observed. At all depths, the 87Sr/ 86Sr ratio of the groundwater is considerably lower than the Sr isotopic ratio of the bulk sediment or its K-feldspar component, but similar to that of a plagioclase-rich accessory separate obtained from the sediment. The Si- 87Sr/ 86Sr-depth relationships are consistent with dissolution of accessory plagioclase. In addition, solutes such as Sr, Ca, and particularly K show concentration spikes superimposed on their respective general trends. The K-Sr- 87Sr/ 86Sr systematics suggests that accessory glauconite is another major solute source to Cape Cod groundwater. Although the authigenic glauconite in the Cape Cod sediment is rich in Rb, it is low in in-grown radiogenic 87Sr because of its young Pleistocene age. The low 87Sr/ 86Sr ratios are consistent with equilibration of glauconite with seawater. The impact of glauconite is inferred to vary due to its variable abundance in the sediments. In the Cape Cod groundwater, the variation of REY concentrations with sampling depth resembles that of K and Rb, but differs from that of Ca and Sr. Shale-normalized REY patterns are light REY depleted, show negative Ce anomalies and super-chondritic Y/Ho ratios, but no Eu anomalies. REY input from feldspar, therefore, is insignificant compared to input from a K-Rb-bearing phase, inferred to be glauconite. These results emphasize that interpretation of

  8. [Energy related studies utilizing K-feldspar thermochronology]. Progress report, 1991--1992

    SciTech Connect

    Not Available

    1992-03-01

    In our second year of current funding cycle, we have investigated the Ar diffusion properties and microstructures of K-feldspars and the application of domain theory to natural K-feldspars. We completed a combined TEM and argon diffusion study of the effect of laboratory heat treatment on the microstructure and kinetic properties of K-feldspar. We conclude in companion papers that, with one minor exception, no observable change in the diffusion behavior occurs during laboratory extraction procedures until significant fusion occurs at about 1100{degrees}C. The effect that is observed involves a correlation between the homogenization of cryptoperthite lamelle and the apparent increase in retentivity of about 5% of the argon in the K-feldspar under study. We can explain this effect of both as an artifact of the experiment or the loss of a diffusion boundary. Experiments are being considered to resolve this question. Refinements have been made to our experimental protocol that appears that greatly enhance the retrieval of multi-activation energies from K-feldspars. We have applied the multi-domain model to a variety of natural environments (Valles Caldera, Red River fault, Appalachian basin) with some surprising results. Detailed {sup 40}Ar/{sup 39} Ar coverage of the Red River shear zone, thought to be responsible for the accommodation of a significant fraction of the Indo-Asian convergence, strongly suggests that our technique can precisely date both the termination of ductile strike-slip motion and the initiation of normal faulting. Work has continued on improving our numerical codes for calculating thermal histories and the development of computer based graphing tools has significantly increased our productivity.

  9. CO2 Sequestration in Feldspar-Rich Sandstone: The Importance of Saturation State and Fluid Composition

    NASA Astrophysics Data System (ADS)

    Tutolo, B. M.; Luhmann, A. J.; Kong, X. Z.; Seyfried, W. E., Jr.; Saar, M. O.

    2014-12-01

    To investigate CO2 Capture, Utilization, and Storage (CCUS) in sandstones, we performed 150°C flow-through experiments on K-feldspar rich cores from the Eau Claire Formation. We observed mass transfer processes operating on a range of scales by measuring sample porosity, permeability, and surface area and fluid and solid chemistry. The close agreement between our measured K-feldspar dissolution rates and literature values demonstrate that feldspar-fluid interaction can be confidently modeled using our chosen rate parameters and characterization methods, but other hydrogeochemical processes evolve somewhat less predictably. Specifically, a sandstone core through which CO2-rich deionized water was recycled for 52 days decreased in porosity and permeability and increased in surface area while an Al hydroxide mineral, such as boehmite, precipitated within its pore space. However, two samples subjected to ~3 day single-pass experiments run with CO2-rich NaCl brines generally increased in porosity and surface area and decreased in permeability as K-feldspar was converted to a phase with kaolinite-like stoichiometry. Notably, boehmite remained two orders of magnitude less supersaturated than kaolinite in all samples from all experiments, and we therefore hypothesize that the identity of the secondary phase is related to the presence of NaCl in solution. Regardless of their identity, long-lived secondary phase supersaturations and low measured Al molalities suggest that Al is precipitated at approximately the same rate at which it is released to solution through feldspar hydrolysis. Finally, we note that, although core permeability measurably decreased in all three experiments, the magnitude of these changes is unlikely to impact CO2 injectivity over a CCUS reservoir's lifetime. The observations produced here are critical to the application of reactive transport models to CCUS systems, yet more work will be required in order to improve model predictions.

  10. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Kjøll, H. J.; Viola, G.; Menegon, L.; Sørensen, B. E.

    2015-01-01

    A coarse grained, statically crystallized quartz vein, embedded in a phyllonitic matrix, was studied by EBSD and optical microscopy to gain insights into the processes of strain localization in quartz deformed under low-grade conditions, broadly coincident with the frictional-viscous transition. The vein is from a high strain zone at the front of the Porsa Imbricate Stack in the Paleoproterozoic Repparfjord Tectonic Window in northern Norway. The vein was deformed under lower greenschist facies conditions during deformation along a large out-of-sequence phyllonitic thrust of Caledonian age. The host phyllonite formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation was initially accommodated by basal ⟨a⟩ slip of quartz during the development of a mesoscopic pervasive extensional crenulation cleavage. Under the prevailing boundary conditions, however, dislocation glide-accommodated deformation of quartz resulted inefficient and led to dislocation tangling and strain hardening of the vein. In response to hardening, to the progressive increase of fluid pressure and the increasing competence contrast between the vein and the weak foliated host phyllonite, quartz crystals began to deform frictionally along specific, optimally oriented lattice planes, creating microgouges along microfractures. These were, however, rapidly sealed by nucleation of new grains as transiently over pressured fluids penetrated the deforming system. The new nucleated grains grew initially by solution-precipitation and later by grain boundary migration. Due to the random initial orientation of the vein crystals, strain was accommodated differently in the individual crystals, leading to the development of remarkably different microstructures. Crystals

  11. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    PubMed Central

    Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2014-01-01

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis. PMID:24686729

  12. Quartz Mountain/Oklahoma Summer Arts Institute.

    ERIC Educational Resources Information Center

    Frates, Mary Y.; Madeja, Stanley S.

    1982-01-01

    Describes the Quartz Mountain Oklahoma Summer Arts Institute program. It is designed to nurture artistic talent and to provide intensive arts experiences in music, dance, theater, and the visual arts for talented students aged 14-18. (AM)

  13. Quartz crystal microbalance use in biological studies

    NASA Technical Reports Server (NTRS)

    Green, R. H.; Godfrey, J. F.; Laue, E. G.; Laue, T. M.; Paik, W. W.; Wardle, M. D.

    1972-01-01

    Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described.

  14. Process for the disposal of alkali metals

    DOEpatents

    Lewis, Leroy C.

    1977-01-01

    Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level.

  15. The alkali metals: 200 years of surprises.

    PubMed

    Dye, James L

    2015-03-13

    Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides! PMID:25666067

  16. Erosion-corrosion of cooled thermal sprayed coatings impacted by mixtures of quartz and chemically active compounds

    SciTech Connect

    Wang, B.; Luer, K.

    1996-08-01

    A series of erosion-corrosion tests was carried out on AISI 1018 steel and four thermal sprayed coatings using a nozzle type elevated temperature erosion tester. The erodent particles were mechanical mixtures of SiO{sub 2} (quartz) with 1--4% NaCl or 1--4% KCl. The specimens were water-cooled on the backside. Test conditions attempted to simulate erosion-corrosion (E-C) conditions at the tubes in the convection pass of FBC boilers. The effect of Cl-bearing salt/quartz mixtures on the E-C wastage mechanisms of these materials were investigated. It was found that the E-C wastage of 1018 steel and carbide coating specimens increased with increasing amounts of NaCl and KCl doped in the quartz. Among the four coatings tested, a WC-17CoCr coating demonstrated the lowest thickness loss of all of the quartz/salt mixtures while the Cr{sub 3}C{sub 2}-25NiCr coating exhibited the highest E-C wastage. Meanwhile, quartz doped with NaCl or KCl had no effect on the E-C wastage of an HVOF Ni20Cr15Mo metal coating. The accelerating effect of doping alkali chlorides increased with both specimen surface temperature and environmental temperature.

  17. Quartz resonator fluid monitors for vehicle applications

    SciTech Connect

    Cernosek, R.W.; Martin, S.J.; Wessendorf, K.O.; Terry, M.D.; Rumpf, A.N.

    1994-09-01

    Thickness shear mode (TSM) quartz resonators operating in a new {open_quotes}Lever oscillator{close_quotes} circuit are used as monitors for critical automotive fluids. These monitors respond to the density and viscosity of liquids contacting the quartz surface. Sensors have been developed for determining the viscosity characteristics of engine lubricating oil, the state-of-charge of lead-acid storage batteries, and the concentration variations in engine coolant.

  18. Quartz resonator fluid monitors for vehicle applications

    NASA Astrophysics Data System (ADS)

    Cernosek, R. W.; Martin, S. J.; Wessendorf, K. O.; Terry, M. D.; Rumpf, A. N.

    Thickness shear mode (TSM) quartz resonators operating in a new 'Lever oscillator' circuit are used as monitors for critical automotive fluids. These monitors respond to the density and viscosity of liquids contacting the quartz surface. Sensors have been developed for determining the viscosity characteristics of engine lubricating oil, the state-of-charge of lead-acid storage batteries, and the concentration variations in engine coolant.

  19. New hole centers in natural quartz

    NASA Astrophysics Data System (ADS)

    Maschmeyer, D.; Lehmann, G.

    1983-11-01

    In natural citrines five new hole centers were detected and analyzed by electron paramagnetic resonance. An additional one was observed in rose-colored quartz crystals with radiation defects as the cause of coloration. Characteristic hyperfine patterns due to an adjacent aluminum impurity were resolved in the spectra of three of these centers. Their relations to other hole centers of well-known structure in quartz and fused silica are discussed and possible models for their structures are proposed.

  20. Method of making a quartz resonator

    DOEpatents

    Vig, John R.; Filler, Raymond L.; Peters, R. Donald; Frank, James M.

    1981-01-01

    A quartz resonator is made from a chemically polished quartz plate. The plate is placed in an enclosure fitted with at least three mounting clips to receive the plate. The plate is secured to the clips with an electrically conductive adhesive capable of withstanding operation at 350 degrees C. The assembly is cleaned and a metallic electrode deposited onto the plate until the desired frequency is reached. The enclosure is then hermetically sealed. The resulting resonator can consistently withstand extremely high shocks.

  1. Studies on interfacial behavior and wettability change phenomena by ionic and nonionic surfactants in presence of alkalis and salt for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Mandal, Ajay

    2016-05-01

    Surfactant flooding is one of the most promising method of enhanced oil recovery (EOR) used after the conventional water flooding. The addition of alkali improves the performance of surfactant flooding due to synergistic effect between alkali and surfactant on reduction of interfacial tension (IFT), wettability alteration and emulsification. In the present study the interfacial tension, contact angle, emulsification and emulsion properties of cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polysorbate 80 (Tween 80) surfactants against crude oil have been investigated in presence of sodium chloride (NaCl) and alkalis viz. sodium hydroxide (NaOH), sodium carbonate (Na2CO3), ammonium hydroxide (NH4OH), sodium metaborate (SMB) and diethanolamine (DEA). All three surfactants significantly reduce the IFT values, which are further reduced to ultra-low value (∼10-4 mN/m) by addition of alkalis and salt. It has been found experimentally that alkali-surfactant systems change the wettability of an intermediate-wet quartz rock to water-wet. Emulsification of crude oil by surfactant and alkali has also been investigated in terms of the phase volume and stability of emulsion. A comparative FTIR analysis of crude oil and different emulsions were performed to investigate the interactions between crude oil and displacing water in presence of surfactant and alkali.

  2. Method of handling radioactive alkali metal waste

    DOEpatents

    Wolson, Raymond D.; McPheeters, Charles C.

    1980-01-01

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  3. Method of handling radioactive alkali metal waste

    DOEpatents

    Wolson, R.D.; McPheeters, C.C.

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  4. ESR studies on bleached sedimentary quartz

    NASA Astrophysics Data System (ADS)

    Walther, R.; Zilles, D.

    Some ESR signals in quartz are reported to be bleachable by sunlight and so they promise to be useful for dating sediments (Grün, 1989). The Ge signal in quartz is the only one that shows bleaching effects with UV light in short time scales (hours). Therefore we used quartz samples from the sites of Mauer ( 'Homo erectus heidelbergensis'), samples from a borehole in the Neckar valley ('Entensee', Ladenburg near Heidelberg) and samples from a pegmatite for basic studies on the Ge signal. The results show that with our standard sample preparation procedure for quartz separation (using red light as for TL samples), the natural Ge signal is not detectable, but rises clearly with gamma irradiation. Several experiments for examination of the stability and sensitivity of the Ge centre in quartz were carried out. For comparison with the behaviour of the Ge signal we measured the Al signal as well. Our experiments show that the Al signal is bleachable in long time scales (weeks). The behaviour on bleaching, irradiation and thermal annealing is very complicated, as the Al centre is a hole centre (it possibly interacts with several electron centres in the quartz and so the processes are of higher order).

  5. The mineralogy and geochemistry of quartz-tourmaline schlieren in the granites of the Primorsky Complex, Western Baikal Region

    NASA Astrophysics Data System (ADS)

    Savel'eva, V. B.; Bazarova, E. P.; Kanakin, S. V.

    2014-12-01

    Quartz-tourmaline schlieren have been found within rapakivi-like granites of the Early Proterozoic Primorsky Complex in the Western Baikal Region. These rocks are biotite leucogranites with normal alkalinity (A/CNK = 1.00-1.04); a high iron mole fraction (92-95%); a K2O/Na2O value of about 2.0; relatively high F, Li, Rb, Cs, Sn, Pb, Th, and U contents; and low Ba, Sr, Eu, Zn, Sc, and V contents. The schlieren composed of quartz and tourmaline with relics of feldspar also contain fluorite, rare muscovite, chlorite, and accessory rutile, ilmenite, zircon, monazite, xenotime, and bastnäsite. B2O3 and F contents in the schlieren are 2.29-2.63 and 0.30-0.47 wt %, respectively. Fe2O3 (4.8-5.4 wt %), F, and H2O contents are higher in these schlieren than in the host granite, while SiO2, CaO, Na2O, K2O, and P2O5 contents are lower than in host rocks. K2O/Na2O values decrease in the schlieren down to 0.4. Enrichment of the schlieren in Fe and other ore elements (Zn, Co, Cu, Sn, etc.), together with B, F, H2O, and Na, suggests that they crystallized from fluid-saturated melt segregated from aluminosilicate melt in the apical part of a shallow-seated intrusion. The formation of tourmaline may be related to the interaction of the fluid with feldspars in the crystallizing granites; it was accompanied by a separation of fluid F-CO2. Quartz precipitated at the next stage, due to the acidic character of the aqueous fluid. In general, the relationships of minerals in the schlieren indicate distinct fractionation of LREE, HREE, and Y in the fluid-saturated melt.

  6. Intensity of quartz cathodoluminescence and trace-element content in quartz from the porphyry copper deposit at Butte, Montana

    USGS Publications Warehouse

    Rusk, B.G.; Reed, M.H.; Dilles, J.H.; Kent, A.J.R.

    2006-01-01

    Textures of hydrothermal quartz revealed by cathodoluminescence using a scanning electron microscope (SEM-CL) reflect the physical and chemical environment of quartz formation. Variations in intensity of SEM-CL can be used to distinguish among quartz from superimposed mineralization events in a single vein. In this study, we present a technique to quantify the cathodoluminescent intensity of quartz within individual and among multiple samples to relate luminescence intensity to specific mineralizing events. This technique has been applied to plutonic quartz and three generations of hydrothermal veins at the porphyry copper deposit in Butte, Montana. Analyzed veins include early quartz-molybdenite veins with potassic alteration, pyrite-quartz veins with sericitic alteration, and Main Stage veins with intense sericitic alteration. CL intensity of quartz is diagnostic of each mineralizing event and can be used to fingerprint quartz and its fluid inclusions, isotopes, trace elements, etc., from specific mineralizing episodes. Furthermore, CL intensity increases proportional to temperature of quartz formation, such that plutonic quartz from the Butte quartz monzonite (BQM) that crystallized at temperatures near 750 ??C luminesces with the highest intensity, whereas quartz that precipitated at ???250 ??C in Main Stage veins luminesces with the least intensity. Trace-element analyses via electron microprobe and laser ablation-ICP-MS indicate that plutonic quartz and each generation of hydrothermal quartz from Butte is dominated by characteristic trace amounts of Al, P, Ti, and Fe. Thus, in addition to CL intensity, each generation of quartz can be distinguished based on its unique trace-element content. Aluminum is generally the most abundant element in all generations of quartz, typically between 50 and 200 ppm, but low-temperature, Main Stage quartz containing 400 to 3600 ppm Al is enriched by an order of magnitude relative to all other quartz generations. Phosphorous

  7. Example of trondhjemite genesis by means of alkali metasomatism: Rockford Granite, Alabama Appalachians

    SciTech Connect

    Drummond, M.S.; Wesolowski, D.; Ragland, P.C.; Ragland, J.

    1985-01-01

    An alternative model for trondhjemite genesis is proposed where granite is transformed to trondhjemite via infiltration by a Na-rich metamorphic fluid. The Rockford Granite serves as the case example for this process and is characterized as a synmetamorphic, peraluminous trondhjemite-granite suite. The major process operative in the conversion of granite to trondhjemite involves cation exchange of Na for K in the feldspar and mica phases through a volatile fluid medium. Whole-rock delta/sup 18/O values for the trondhjemites are negatively correlated with the atomic prop. K/Na ratio indicating a partial reequilibration of the altered granitoids with a Na- and /sup 18/O-rich metamorphically derived fluid. Biotite decomposition to an Al-epidote-paragonitic muscovite-quartz assemblage is also associated with the Na-metasomatism, as are apatite replacement by Al-epidote and secondary zircon crystallization. The replacement of magmatic phases by metasomatic phases exemplifies the chemical changes produced during infiltration metasomatism where the trondhjemites are depleted in all REE's. The timing of the infiltration metasomatism is thought to have occurred during regional metamorphism, producing a discrete fluid phase in the surrounding amphibolite-grade metasediments. Foliation planes in the granitoid apparently served as conduts for fluid flow with reaction enhanced permeability accompanying the 8% molar volume reduction during Na for K exchange in the feldspars. A model is proposed where metamorphic fluids migrated updip and along strike from their source and were buffered by the presence or absence of two feldspars in the metasediments.

  8. Study on water-dispersible colloids in saline-alkali soils by atomic force microscopy and spectrometric methods.

    PubMed

    Liu, Zhiguo; Xu, Fengjie; Zu, Yuangang; Meng, Ronghua; Wang, Wenjie

    2016-06-01

    Recent studies have revealed that water-dispersible colloids play an important role in the transport of nutrients and contaminants in soils. In this study, water-dispersible colloids extracted from saline-alkali soils have been characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV absorption spectra. AFM observation indicated that the water-dispersible colloids contain some large plates and many small spherical particles. XRD, XPS, and UV absorption measurement revealed that the water-dispersible colloids are composed of kaolinite, illite, calcite, quartz and humic acid. In addition, UV absorption measurement demonstrated that the humic acids are associated with clay minerals. Water-dispersible colloids in the saline-alkali soils after hydrolyzed polymaleic anhydride treatment and an agricultural soil (nonsaline-alkali soil) were also investigated for comparison. The obtained results implied that the saline-alkali condition facilitates the formation of a large quantity of colloids. The use of AFM combined with spectrometric methods in the present study provides new knowledge on the colloid characteristics of saline-alkali soils. Microsc. Res. Tech. 79:525-531, 2016. © 2016 Wiley Periodicals, Inc. PMID:27062427

  9. Alkali burns from wet cement.

    PubMed Central

    Peters, W. J.

    1984-01-01

    When water is added to the dry materials of Portland cement calcium hydroxide is formed; the wet cement is caustic (with a pH as high as 12.9) and can produce third-degree alkali burns after 2 hours of contact. Unlike professional cement workers, amateurs are usually not aware of any danger and may stand or kneel in the cement for long periods. As illustrated in a case report, general physicians may recognize neither the seriousness of the injury in its early stages nor the significance of a history of prolonged contact with wet cement. All people working with cement should be warned about its dangers and advised to immediately wash and dry the skin if contact does occur. Images Fig. 1 PMID:6561052

  10. Age of K-feldspar authigenesis in Lower Paleozoic and uppermost Precambrian rocks of the Mississippi Valley area

    SciTech Connect

    Hay, R.L.; Liu, J. . Dept. of Geology); Deino, A. . Geochronology Center); Kyser, T.K. . Dept. of Geology)

    1992-01-01

    Published K-Ar dates (n = 12) of authigenic K-feldspar in Cambrian and Ordovician rocks of the Mississippi Valley area range from 448 to 375 Ma (Late Ordovician to Middle Devonian), suggesting a lengthy episode of K-feldspar authigenesis. Here the authors report an age span of 465--400 Ma (Middle Ordovician to Early Devonian) for authigenic K-feldspar of two samples from the alteration profile widely developed over Precambrian rocks at the unconformity with Cambrian deposits. This dating was done on 42 to 48 mesh grains of K-feldspar by the laser incremental-heating Ar-40/Ar-39 method. One sample, from west-central Wisconsin, is from a vein formed along a fracture in kaolinitic altered granite. Three grains nearest the fracture yielded plateau ages with a range of 9 Ma and an average of 430 Ma. Three grains distant from the fracture yielded a similar range of 10 Ma but with an average age of 397 Ma. Thus the grains grew over an extended period from at least 430 to 400 Ma. The other sample, from the St. Francois Mts. of Missouri, is of diabase replaced by K-feldspar. Three grains yielded plateau ages ranging over 20 Ma and apparently recording an extended history of K-feldspar growth. The average age of these grains is 454 Ma, compared to a K-Ar date of 444 [+-] 9 Ma obtained from a split of the same sample. The period(s) of K-feldspar authigenesis does not support its linkage with orogenic activity. Oxygen-isotope values of authigenic K-feldspar from lower Paleozoic and uppermost Precambrian rocks range from +19.8 to +23.0 [per thousand] and average 21.4 [per thousand] (N = 11). These values are compatible with formation of the K-feldspar from similar fluids and comparable temperatures.

  11. Effects of chemical surface modification on the ice nucleation ability of feldspar and illite

    NASA Astrophysics Data System (ADS)

    Augustin, Stefanie; Wex, Heike; Kanter, Sandra; Ebert, Martin; Niedermeier, Dennis; Stratmann, Frank

    2014-05-01

    Mineral dust is the most abundant ice nuclei (IN) in the atmosphere and thus it is thought to be important for ice nucleation in clouds (Murray et al. [2012]). The clay minerals contribute approximately two thirds of the mineral dust mass (Atkinson et al. [2013]), and illite is the most abundant clay mineral found in the atmosphere [Broadley et al., 2012]. In the past years a lot of the ice nucleation research focused on proxies for clay minerals like Arizona Test Dust (ATD), kaolinite and illite (see reviews by Murray et al. [2012] and Hoose and Möhler. [2012]). In most experiments, these substances acted as IN only at relatively low temperatures (lower than -25°C). Very recently Atkinson et al. (2013) showed that K-feldspar, which is a common crustal material, is the most active mineral dust with freezing temperatures above -20°C. In the present study we compared the immersion freezing behavior of size segregated illite and feldspar particles. We used illite-NX (Arginotec) and a feldspar sample from Minas Gerais, Brazil (consisting to roughly 80% of a K-feldspar with the remainder being a Na-feldspar). Both substances were examined in the framework of the INUIT research project. For the illite-NX particles freezing onset was observed at temperatures around -34°C. The feldspar sample already induced freezing at -23°C. The data obtained was in agreement to those reported in Broadley el al. [2012] and Atkinson et al. [2013]. To simulate chemical aging of the particle surface we coated the particles with sulfuric acid and repeated the measurements. The illite-NX showed a rather small change in the ice nucleation ability, whereas the freezing ability of the feldspar was strongly reduced and became similar to that of illite-NX. It seems that the sulfuric acid destroyed those sites on the particle surface which are responsible for the initiation of freezing. We continue our work in trying to better understand what exactly it is that gives K-feldspar its good IN

  12. Microfluidic Leaching of Soil Minerals: Release of K+ from K Feldspar.

    PubMed

    Ciceri, Davide; Allanore, Antoine

    2015-01-01

    The rate of K+ leaching from soil minerals such as K-feldspar is believed to be too slow to provide agronomic benefit. Currently, theories and methods available to interpret kinetics of mineral processes in soil fail to consider its microfluidic nature. In this study, we measure the leaching rate of K+ ions from a K-feldspar-bearing rock (syenite) in a microfluidic environment, and demonstrate that at the spatial and temporal scales experienced by crop roots, K+ is available at a faster rate than that measured with conventional apparatuses. We present a device to investigate kinetics of mineral leaching at an unprecedented simultaneous resolution of space (~101-102 μm), time (~101-102 min) and fluid volume (~100-101 mL). Results obtained from such a device challenge the notion that silicate minerals cannot be used as alternative fertilizers for tropical soils. PMID:26485160

  13. Microfluidic Leaching of Soil Minerals: Release of K+ from K Feldspar

    PubMed Central

    Ciceri, Davide; Allanore, Antoine

    2015-01-01

    The rate of K+ leaching from soil minerals such as K-feldspar is believed to be too slow to provide agronomic benefit. Currently, theories and methods available to interpret kinetics of mineral processes in soil fail to consider its microfluidic nature. In this study, we measure the leaching rate of K+ ions from a K-feldspar-bearing rock (syenite) in a microfluidic environment, and demonstrate that at the spatial and temporal scales experienced by crop roots, K+ is available at a faster rate than that measured with conventional apparatuses. We present a device to investigate kinetics of mineral leaching at an unprecedented simultaneous resolution of space (~101-102 μm), time (~101-102 min) and fluid volume (~100-101 mL). Results obtained from such a device challenge the notion that silicate minerals cannot be used as alternative fertilizers for tropical soils. PMID:26485160

  14. Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

    NASA Astrophysics Data System (ADS)

    Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank; Chithambo, Makaiko L.

    2016-09-01

    Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IRSL signals, both during and after short infrared stimulation pulses. The equations are developed using a recently proposed kinetic model, which describes localized electronic recombination via tunneling between trapped electrons and recombination centers in luminescent materials. Recombination is assumed to take place from the excited state of the trapped electron to the nearest-neighbor center within a random distribution of luminescence recombination centers. Different possibilities are examined within the model, depending on the relative importance of electron de-excitation and recombination. The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results.

  15. 40Ar/39Ar ages in deformed potassium feldspar: evidence of microstructural control on Ar isotope systematics

    NASA Astrophysics Data System (ADS)

    Reddy, Steven M.; Potts, Graham J.; Kelley, Simon P.

    2001-05-01

    Detailed field and microstructural studies have been combined with high spatial resolution ultraviolet laser 40Ar/39Ar dating of naturally deformed K-feldspar to investigate the direct relationship between deformation-related microstructure and Ar isotope systematics. The sample studied is a ~1,000 Ma Torridonian arkose from Skye, Scotland, that contains detrital feldspars previously metamorphosed at amphibolite-facies conditions ~1,700 Ma. The sample was subsequently deformed ~430 Ma ago during Caledonian orogenesis. The form and distribution of deformation-induced microstructures within three different feldspar clasts has been mapped using atomic number contrast and orientation contrast imaging, at a range of scales, to identify intragrain variations in composition and lattice orientation. These variations have been related to thin section and regional structural data to provide a well-constrained deformation history for the feldspar clasts. One hundred and forty-three in-situ 40Ar/39Ar analyses measured using ultraviolet laser ablation record a range of apparent ages (317-1030 Ma). The K-feldspar showing the least strain records the greatest range of apparent ages from 420-1,030 Ma, with the oldest apparent ages being found close to the centre of the feldspar away from fractures and the detrital grain boundary. The most deformed K-feldspar yields the youngest apparent ages (317-453 Ma) but there is no spatial relationship between apparent age and the detrital grain boundary. Within this feldspar, the oldest apparent ages are recorded from orientation domain boundaries and fracture surfaces where an excess or trapped 40Ar component resides. Orientation contrast images at a similar scale to the Ar analyses illustrate a significant deformation-related microstructural difference between the feldspars and we conclude that deformation plays a significant role in controlling Ar systematics of feldspars at both the inter- and intragrain scales even at relatively low

  16. Integrating Sphere Alkali-Metal Vapor Cells

    NASA Astrophysics Data System (ADS)

    McGuyer, Bart; Ben-Kish, Amit; Jau, Yuan-Yu; Happer, William

    2010-03-01

    An integrating sphere is an optical multi-pass cavity that uses diffuse reflection to increase the optical path length. Typically applied in photometry and radiometry, integrating spheres have previously been used to detect trace gases and to cool and trap alkali-metal atoms. Here, we investigate the potential for integrating spheres to enhance optical absorption in optically thin alkali-metal vapor cells. In particular, we consider the importance of dielectric effects due to a glass container for the alkali-metal vapor. Potential applications include miniature atomic clocks and magnetometers, where multi-passing could reduce the operating temperature and power consumption.

  17. Alkali Silicate Vehicle Forms Durable, Fireproof Paint

    NASA Technical Reports Server (NTRS)

    Schutt, John B.; Seindenberg, Benjamin

    1964-01-01

    The problem: To develop a paint for use on satellites or space vehicles that exhibits high resistance to cracking, peeling, or flaking when subjected to a wide range of temperatures. Organic coatings will partially meet the required specifications but have the inherent disadvantage of combustibility. Alkali-silicate binders, used in some industrial coatings and adhesives, show evidence of forming a fireproof paint, but the problem of high surface-tension, a characteristic of alkali silicates, has not been resolved. The solution: Use of a suitable non-ionic wetting agent combined with a paint incorporating alkali silicate as the binder.

  18. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  19. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  20. Advancements in flowing diode pumped alkali lasers

    NASA Astrophysics Data System (ADS)

    Pitz, Greg A.; Stalnaker, Donald M.; Guild, Eric M.; Oliker, Benjamin Q.; Moran, Paul J.; Townsend, Steven W.; Hostutler, David A.

    2016-03-01

    Multiple variants of the Diode Pumped Alkali Laser (DPAL) have recently been demonstrated at the Air Force Research Laboratory (AFRL). Highlights of this ongoing research effort include: a) a 571W rubidium (Rb) based Master Oscillator Power Amplifier (MOPA) with a gain (2α) of 0.48 cm-1, b) a rubidium-cesium (Cs) Multi-Alkali Multi-Line (MAML) laser that simultaneously lases at both 795 nm and 895 nm, and c) a 1.5 kW resonantly pumped potassium (K) DPAL with a slope efficiency of 50%. The common factor among these experiments is the use of a flowing alkali test bed.

  1. Gamma activity of stream sediment feldspars as ceramic raw materials and their environmental impact.

    PubMed

    Aboelkhair, Hatem; Ibrahim, Tarek; Saad, Ahmed

    2012-08-01

    In situ gamma spectrometric measurements have been performed to characterise the natural radiation that emitted from the stream sediment feldspars in Wadi El Missikat and Wadi Homret El Gergab, Eastern Desert, Egypt. The measurements of potassium (K, %), equivalent uranium (eU, ppm) and equivalent thorium (eTh, ppm) were converted into specific activities and equivalent dose rate. The average specific activities were 1402 Bq kg(-1) for K, 113 Bq kg(-1) for eU and 108 Bq kg(-1) for eTh in Wadi El Missikat, while they were 1240, 104 and 185 Bq kg(-1) in Wadi Homret El Gergab. The calculated outdoor average effective dose rates was 1.1 mSv y(-1) in wadi El Missikat and 1.3 mSv y(-1) in Wadi Homret El Gergab. The terrestrial-specific activities and effective dose rate levels of the natural radioactivity in the two areas lie within the international recommended limits for occupational feldspar quarry workers. On the other hand, these results indicated that irradiation is higher than the allowable level for members of the public. Therefore, quarrying the feldspar sediments from these locations as ceramic raw materials may yield an undesired impact on the environment, especially through the indoor applications. PMID:22171098

  2. Preparation of ultrafine silica from potash feldspar using sodium carbonate roasting technology

    NASA Astrophysics Data System (ADS)

    Liu, Jia-nan; Shen, Xiao-yi; Wu, Yan; Zhang, Jun; Zhai, Yu-chun

    2016-08-01

    A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na2CO3 and was followed by leaching using NaOH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na2CO3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO2 was 98.13%. The optimized carbonation conditions included a final solution pH value of 9.0, a temperature of 40°C, a CO2 flow rate of 6 mL/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.

  3. Isochron dating of sediments using luminescence of K-feldspar grains

    NASA Astrophysics Data System (ADS)

    Li, Bo; Li, Sheng-Hua; Wintle, Ann G.; Zhao, Hui

    2008-06-01

    A new method for dating well-bleached sediments is presented, with results for thirteen samples from China. The method uses an isochron constructed from the measurement of natural radiation doses received by potassium-feldspar grains in a range of grain sizes using the infrared stimulated luminescence (IRSL) signal. The age of deposition of the sediment is calculated from this isochron and from the internal dose rate to the grains from 40K and 87Rb in the crystal lattice. This procedure appears to overcome age underestimation due to anomalous fading, a phenomenon that has precluded conventional luminescence dating of K-feldspars and would be applicable to K-feldspars for which the natural dose is beyond the linear dose response region. Also, since the isochron IRSL method is reliant on only the internal dose rate, it overcomes problems related to (1) changes in past dose rate due to postdepositional migration of radionuclides, (2) changes in water content as water-lain sediments dry out, (3) spatial heterogeneity in the gamma dose rate, and (4) uncertainties in the cosmic ray dose rate during the period of sample burial.

  4. Titanium, vanadium, and niobium mineralization and alkali metasomatism from the Magnet Cove complex, Arkansas

    USGS Publications Warehouse

    Flohr, M.J.K.

    1994-01-01

    The Christy deposit formed through a series of complex processes. The initial phase of mineralization is directly related to the infiltration of novaculite by alkali-rich fluids that were probably derived from carbonatite magma. Titanium, V, Nb, and Li were introduced by the alkali-rich fluids at temperatures that were as high as 600??C. During the initial stage of mineralization, V was concentrated in aegirine and sodic amphibole, Li was concentrated in taeniolite, minor amounts of Ti were concentrated in aegirine, and pyrite formed. The replacement of novaculite by the aforementioned minerals yielded excess silica, which precipitated as quartz. Niobium- and V-bearing brookite precipitated with the quartz. Minerals formed during the first stage reacted with a second fluid at temperatures of 100?? to 300??C and V was then concentrated in smectite and goethite. The second fluid was a mixture of low-temperature metasomatic fluid and groundwater. Vanadium was further concentrated in clay minerals in goethite, and in vug minerals as low-temperature alteration proceeded. -from Author

  5. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick (Inventor); Fraschetti, George A. (Inventor); Mccann, Timothy A. (Inventor); Mayall, Sherwood D. (Inventor); Dunn, Donald E. (Inventor); Trauger, John T. (Inventor)

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  6. Adsorption of goethite onto quartz and kaolinite

    USGS Publications Warehouse

    Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

    1984-01-01

    The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

  7. Sediment grain size and surface textural observations of quartz grains in late quaternary lacustrine sediments from Schirmacher Oasis, East Antarctica: Paleoenvironmental significance

    NASA Astrophysics Data System (ADS)

    Warrier, Anish Kumar; Pednekar, Hemant; Mahesh, B. S.; Mohan, Rahul; Gazi, Sahina

    2016-03-01

    In this study we report the sediment grain size parameters and surface textural observations (using scanning electron microscopy (SEM)) of quartz grains from sediments of Sandy Lake, Schirmacher Oasis, East Antarctica. The sediment core spans the last 43 cal ka B.P. The statistical parameters of grain size data (sorting, skewness, kurtosis, mean grain size, D10, D50, D90 and SPAN index) indicate that the sediments are primarily transported by melt-water streams and glaciers. However, during the last glacial period, sediments seem to be transported due to wind activity as evident by the good correlation between rounded quartz data and dust flux data from EPICA ice-core data. The mean grain size values are low during the last glacial period indicating colder climatic conditions and the values increase after the last glacial maximum suggesting an increase in the energy of the transporting medium, i.e., melt-water streams. The sediments are poorly sorted and finely skewed and show different modes of grain size distribution throughout the last 43 cal ka B.P. SEM studies of selected quartz grains and analyses of various surface textures indicate that glacigenic conditions must have prevailed at the time of their transport. Semi-quantitative analyses of mineral (quartz, feldspar, mica, garnet and rock fragments & other minerals) counts suggest a mixed population of minerals with quartz being the dominant mineral. Higher concentration of quartz grains over other minerals indicates that the sediments are compositionally mature. The study reveals the different types of physical weathering, erosive signatures, and chemical precipitation most of them characteristic of glacial environment which affected these quartz grains before final deposition as lake sediments. The palaeoclimatic signals obtained from this study show similarities with ice-core and lake sediment records from Schirmacher Oasis and other ice-free regions in East Antarctica.

  8. Alkali Metal Handling Practices at NASA MSFC

    NASA Technical Reports Server (NTRS)

    Salvail, Patrick G.; Carter, Robert R.

    2002-01-01

    NASA Marshall Space Flight Center (MSFC) is NASA s principle propulsion development center. Research and development is coordinated and carried out on not only the existing transportation systems, but also those that may be flown in the near future. Heat pipe cooled fast fission cores are among several concepts being considered for the Nuclear Systems Initiative. Marshall Space Flight Center has developed a capability to handle high-purity alkali metals for use in heat pipes or liquid metal heat transfer loops. This capability is a low budget prototype of an alkali metal handling system that would allow the production of flight qualified heat pipe modules or alkali metal loops. The processing approach used to introduce pure alkali metal into heat pipe modules and other test articles are described in this paper.

  9. Alkali-metal intercalation in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  10. Age and thermochronology of K-feldspars from the Manson Impact Structure

    NASA Technical Reports Server (NTRS)

    Zeitler, P. K.; Kunk, M. J.

    1993-01-01

    As a contribution to the effort to obtain a precise age for the Manson Impact Structure, we are approaching the problem from a thermo chronological perspective, with the goal of extracting an age from Ar-40/Ar-39 age-spectrum analysis of partially overprinted K-feldspars taken from granitoid clasts. We find that shocked feldspars from Manson generally show a strong overprint in their age spectra, with more than 50 percent of each spectrum being reset. The reset portions of the age spectra correspond to gas lost from very small diffusion domains, and a characteristic of the Manson samples is the very large range in apparent diffusion dimensions that they display, with the smallest domains being some 400 times smaller than the largest domains. It is also noteworthy that the small domains comprise a substantial portion of the volume of the feldspars (50 percent or more). These observations are consistent with the extreme shock experienced by these samples. In detail, the spectra we have measured to date are saddle-shaped and show minimum ages of between 67 and 72 Ma, which we interpret to be maximum estimates for the age of the impact. In the case of one sample (M1-678.3; K-feldspar from a large syenite block located well below the apparent melt-matrix breccia in the M1 borehole), isotope correlation analysis suggests the presence of a non-atmospheric trapped Ar component (Ar-40/Ar-36 of 660 plus or minus 40), and an age of about 65.3 plus or minus 0.5 Ma (2 sigma). Our interpretation of our results is that the shock of impact greatly reduced the diffusion-domain sizes of our samples, making them susceptible to significant Ar loss during heating associated with impact. It appears that while our feldspars were partially open to Ar loss, they equilibrated with a non-atmospheric Ar component, probably related to impact-related degassing of old basement around the impact site.

  11. Age and thermochronology of K-feldspars from the Manson Impact Structure

    NASA Astrophysics Data System (ADS)

    Zeitler, P. K.; Kunk, M. J.

    1993-03-01

    As a contribution to the effort to obtain a precise age for the Manson Impact Structure, we are approaching the problem from a thermo chronological perspective, with the goal of extracting an age from Ar-40/Ar-39 age-spectrum analysis of partially overprinted K-feldspars taken from granitoid clasts. We find that shocked feldspars from Manson generally show a strong overprint in their age spectra, with more than 50 percent of each spectrum being reset. The reset portions of the age spectra correspond to gas lost from very small diffusion domains, and a characteristic of the Manson samples is the very large range in apparent diffusion dimensions that they display, with the smallest domains being some 400 times smaller than the largest domains. It is also noteworthy that the small domains comprise a substantial portion of the volume of the feldspars (50 percent or more). These observations are consistent with the extreme shock experienced by these samples. In detail, the spectra we have measured to date are saddle-shaped and show minimum ages of between 67 and 72 Ma, which we interpret to be maximum estimates for the age of the impact. In the case of one sample (M1-678.3; K-feldspar from a large syenite block located well below the apparent melt-matrix breccia in the M1 borehole), isotope correlation analysis suggests the presence of a non-atmospheric trapped Ar component (Ar-40/Ar-36 of 660 plus or minus 40), and an age of about 65.3 plus or minus 0.5 Ma (2 sigma). Our interpretation of our results is that the shock of impact greatly reduced the diffusion-domain sizes of our samples, making them susceptible to significant Ar loss during heating associated with impact. It appears that while our feldspars were partially open to Ar loss, they equilibrated with a non-atmospheric Ar component, probably related to impact-related degassing of old basement around the impact site.

  12. Alkali metal intercalates of molybdenum disulfide.

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1973-01-01

    Study of some of the physicochemical properties of compounds obtained by subjecting natural molybdenite and single crystals of molybdenum disulfide grown by chemical vapor transport to intercalation with the alkali group of metals (Li, Na, K, Rb, and Cs) by means of the liquid ammonia technique. Reported data and results include: (1) the intercalation of the entire alkali metal group, (2) stoichiometries and X-ray data on all of the compounds, and (3) superconductivity data for all the intercalation compounds.

  13. Superconductivity in alkali-doped C60

    NASA Astrophysics Data System (ADS)

    Ramirez, Arthur P.

    2015-07-01

    Superconductivity in alkali-doped C60 (A3C60, A = an alkali atom) is well described by an s-wave state produced by phonon mediated pairing. Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures (Tc) up to 33 K in single-phase material. The good understanding of pairing in A3C60 offers a paradigm for the development of new superconducting materials.

  14. Desulfurizing Coal With an Alkali Treatment

    NASA Technical Reports Server (NTRS)

    Ravindram, M.; Kalvinskas, J. J.

    1987-01-01

    Experimental coal-desulfurization process uses alkalies and steam in fluidized-bed reactor. With highly volatile, high-sulfur bituminous coal, process removed 98 percent of pyritic sulfur and 47 percent of organic sulfur. Used in coal liquefaction and in production of clean solid fuels and synthetic liquid fuels. Nitrogen or steam flows through bed of coal in reactor. Alkalies react with sulfur, removing it from coal. Nitrogen flow fluidizes bed while heating or cooling; steam is fluidizing medium during reaction.

  15. What classic greywacke (litharenite) can reveal about feldspar diagenesis: An example from Permian Rotliegend sandstone in Hessen, Germany

    NASA Astrophysics Data System (ADS)

    Molenaar, Nicolaas; Felder, Marita; Bär, Kristian; Götz, Annette E.

    2015-08-01

    Rotliegend siliciclastic sediments in southern Hessen (Germany) are a good example of dissolution of detrital feldspars, which is a common feature in many sandstones. Dissolution occurred after mechanical compaction of the lithic-rich sandstone, which experienced framework collapse with pores and pore connections filled and obstructed by deformed ductile lithic grains (pseudomatrix) thereby reducing pore space to microporosity., The advanced degree of compaction and reduced porosity caused low permeability and low hydraulic conductivity of the rock mass. This is further reduced by the presence of wackes and shales that occur intercalated with the sandstones. Feldspar dissolution thus took place in low permeable sediments when large-scale flow of meteoric or acidic fluids is ruled out as a cause of feldspar dissolution. Mineral precipitation (illite, kaolinite, and albite) took place within pseudomatrix and detrital matrix as well as in secondary pores created by feldspar dissolution. Feldspar was the source for the authigenesis. The system was thus closed during burial after framework collapse, and diagenetic reactants in the form of detrital components were already present within the system. The original mass was preserved, but redistributed and diagenetic minerals were the local sinks for the dissolved reactants, precipitating within the system. This also suggests that burial diagenesis in general might be more mass conservative than usually assumed. Rotliegend sandstones thus form a case where, despite of the lack of external exchange of mass by fluid flow, major diagenetic processes did take place and significantly modified the original mineralogy and texture. Feldspar diagenesis can take place from other processes than mere large-scale flushing of open systems as often supposed. It implies that the volumes of rock affected by feldspar diagenesis may be much larger than anticipated based upon the common hold believe that feldspar diagenesis is linked to

  16. Comment on “Systematic variations of argon diffusion in feldspars and implications for thermochronometry” by Cassata and Renne

    NASA Astrophysics Data System (ADS)

    Lovera, Oscar M.; Harrison, T. Mark; Boehnke, Patrick

    2015-02-01

    Cassata and Renne (2013) is a data-rich paper potentially providing opportunities to systematically test long-standing models of argon diffusion behavior in feldspars and we congratulate them on a heroic achievement. That said, several of their interpretations are highly problematic due to misconceptions of both the nature of their sample and diffusion modeling. Evidence of grain-scale diffusion in an exsolved feldspar

  17. Alkali metal crystalline polymer electrolytes.

    PubMed

    Zhang, Chuhong; Gamble, Stephen; Ainsworth, David; Slawin, Alexandra M Z; Andreev, Yuri G; Bruce, Peter G

    2009-07-01

    Polymer electrolytes have been studied extensively because uniquely they combine ionic conductivity with solid yet flexible mechanical properties, rendering them important for all-solid-state devices including batteries, electrochromic displays and smart windows. For some 30 years, ionic conductivity in polymers was considered to occur only in the amorphous state above Tg. Crystalline polymers were believed to be insulators. This changed with the discovery of Li(+) conductivity in crystalline poly(ethylene oxide)(6):LiAsF(6). However, new crystalline polymer electrolytes have proved elusive, questioning whether the 6:1 complex has particular structural features making it a unique exception to the rule that only amorphous polymers conduct. Here, we demonstrate that ionic conductivity in crystalline polymers is not unique to the 6:1 complex by reporting several new crystalline polymer electrolytes containing different alkali metal salts (Na(+), K(+) and Rb(+)), including the best conductor poly(ethylene oxide)(8):NaAsF(6) discovered so far, with a conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)(6):LiAsF(6). These are the first crystalline polymer electrolytes with a different composition and structures to that of the 6:1 Li(+) complex. PMID:19543313

  18. AUthigenic feldspar as an indicator of paleo-rock/water interactions in Permian carbonates of the Northern Calcareous Alps, Austria

    USGS Publications Warehouse

    Spotl, C.; Kralik, M.; Kunk, M.J.

    1996-01-01

    Dolostones interbedded with Upper Permian evaporites at the base of the Northern Calcareous Alps contain abundant authigenic K-feldspar. Two petrographically, structurally, and isotopically distinct generations of K-feldspar can be distinguished: crystals composed of an inclusion-rich core and a clear rim, and optically unzoned, transparent crystals. Both feldspar types have essentially identical K-feldspar end-member compositions with ??? 99.5 mole % Or component. Low oxygen isotope ratios (+16.1??? to +18.1??? SMOW) suggest precipitation from 18O-enriched, saline fluids at temperatures in excess of ??? 140??C. 40Ar/39Ar plateau-age spectra of five samples range from 145 ?? 1 to 144 ?? 1 Ma (Early Berriasian) and suggest that both types of feldspar were formed within an interval that did not exceed ??? 2 m.y. Rb/Sr model ages range from 152 to 140 Ma, assuming that the burial diagenetic regime was buffered with respect to strontium by the associated marine Permian evaporites. Authigenic K-feldspar records two distinct events of hot brine flow, most likely triggered by tectonic movements (detachment) and by an increase in the subsurface temperature in response to thrust loading.

  19. Surface chemistry of labradorite feldspar reacted with aqueous solutions at pH = 2, 3, and 12

    NASA Astrophysics Data System (ADS)

    Casey, William H.; Westrich, Henry R.; Arnold, George W.

    1988-12-01

    The reaction of feldspar with an aqueous solution is examined by complementing dissolution rate measurements with analysis of mineral surface chemistry. Rates of feldspar dissolution were measured in H 2O - HCl and D 2O - DCl solutions. These measurements were combined with elastic recoil detection (ERD) analysis of hydrogen isotope concentration, and Rutherford backscattering analysis (RBS) of silicon, aluminum and calcium concentrations near the surface of the mineral. Dissolution rates of labradorite feldspar in H 2O - HCl solutions ( pH = 1.7) are 33% more rapid than in D 2O - DCl mixtures ( pD = 1.7). The depth of penetration and inventory of hydrogen in the feldspar is a strong function of solution pH, temperature, and reaction time. Hydrogen infiltrates the feldspar more extensively from an acidic solution than from a basic solution, and complete isotopic exchange between the hydration layer and water proceeds in time on the order of hours. The hydrolysis of bridging Si - O - Al bonds by reaction with a strongly acidic solution for several hundreds of hours progresses to depths of several hundreds of Angstroms into the mineral. Calcium is also removed from the mineral to this depth during reaction with an acidic solution. The composition of the reacted surface, however, cannot be explained solely on the basis of ion exchange or depolymerization reactions. The data suggest that the silicon-rich surface of feldspar continually repolymerizes during reaction, and that this repolymerization eliminates hydrogen from the hydration layer.

  20. Fluorous-based carbohydrate quartz crystal microbalance.

    PubMed

    Chen, Lei; Sun, Pengfei; Chen, Guosong

    2015-03-20

    Fluorous chemistry has brought many applications from catalysis to separation science, from supramolecular materials to analytical chemistry. However, fluorous-based quartz crystal microbalance (QCM) has not been reported so far. In the current paper, fluorous interaction has been firstly utilized in QCM, and carbohydrate-protein interaction and carbohydrate-carbohydrate interaction have been detected afterward. PMID:25541017

  1. Effects of magma mingling in the granites of Mount Desert Island, Maine

    SciTech Connect

    Seaman, S.J.; Ramsey, P.C. )

    1992-07-01

    Textures and compositional relationships associated with dark-colored, fine-grained enclaves in the Cadillac Mountain and Somesville granites, Mount Desert Island, Maine, preserve abundant evidence for contamination of host granitic magmas by enclave liquids. Fine-grained enclaves, which apparently represent chilled magmatic droplets, have affected the composition and texture of the host granites by three possible mechanisms: (1) crystallization of feldspar-quartz-hornblende pegmatite pods from fluids of enclave origin in the granite surrounding enclaves, and the disaggregation of the pods and dispersion of crystals into the granite; (2) ionic exchange between enclaves and granitic magmas; (3) the generation around enclaves of rinds consisting of an inner alkali feldspar-quartz zone and an outer zone of hornblende-enriched granite. Thermal calculations suggest that the alkali feldspar-quartz zones of the rinds surrounding enclaves may result from resorption of alkali feldspar and quartz crystals in the granitic magma by heat of cooling and crystallization of enclave material. The interaction between the hot enclave and the alkali feldspar-quartz composition liquid may be analogous to that between a pluton and meteoric water in a hydrothermal system. The segregation of alkali feldspar-quartz and hornblende-rich zones may result from the minimum melt composition fluid migrating toward the enclave, leaving behind unmelted hornblende, as part of a convection circuit set up by the enclave. Alternatively, hornblende-rich zones concentric to and outside of the alkali feldspar-quartz rinds may record limit of movement of a front of hydrous fluid driven from the enclave boundary down a thermal gradient.

  2. Solution-precipitation of K-feldspar in deformed granitoids and its relationship to the distribution of water

    NASA Astrophysics Data System (ADS)

    Fukuda, Jun-ichi; Okudaira, Takamoto; Satsukawa, Takako; Michibayashi, Katsuyoshi

    2012-04-01

    We have investigated K-feldspar recrystallisation in granitoid mylonites within a ductile shear zone from the Ryoke metamorphic belt, SW Japan. Fine-grained K-feldspar (20 μm on average) occurs in the matrix and in pull-apart areas within fractured K-feldspar porphyroclasts. These fine grains are elongated and oriented parallel to the main foliation in the matrix, and their grain surfaces, observed with the scanning electron microscope, are not smooth, but rough due to the development of very fine (< 1 μm) round grains of K-feldspar on the surface of each grain. In pull-apart areas, the crystallographic orientation of fine-grained K-feldspar, as measured by electron backscatter diffraction (EBSD), is strongly controlled by that of the host porphyroclast, and shows rotations with shear components parallel to fractures. In the matrix, the crystallographic orientation of fine-grained K-feldspar is not consistent with intracrystalline plasticity, but rather with a growth rate that is slightly controlled by nearby porphyroclasts. All this, together with the growth features on grains, suggests that solution-precipitation of K-feldspar from K-rich aqueous fluid occurred during progressive deformation. Infrared (IR) mapping was performed to evaluate the distribution of water in pull-apart areas and the matrix. Water is heterogeneously distributed within K-feldspar porphyroclasts, which contain 150-2200 ppm H2O. In contrast, the water content is low (150-300 ppm H2O) and homogeneously distributed in fine-grained K-feldspar in the matrix and pull-apart areas, even though included in these analyses are grain boundaries that can generally contain abundant aqueous fluid. The results of EBSD analysis and IR mapping indicate that water is released during solution-precipitation of K-feldspar under mid-crustal conditions. The solution-precipitation process under a water-rich environment in the middle crust results in the formation of fine grains, possibly deforming dominantly by

  3. Effect of ageing of K-feldspar on its ice nucleating efficiency in immersion, deposition and contact freezing modes

    NASA Astrophysics Data System (ADS)

    Peckhaus, Andreas; Bachmann, Felix; Hoffmann, Nadine; Koch, Michael; Kiselev, Alexei; Leisner, Thomas

    2015-04-01

    Recently K-feldspar was identified as one of the most active atmospheric ice nucleating particles (INP) of mineral origin [1]. Seeking the explanation to this phenomena we have conducted extensive experimental investigation of the ice nucleating efficiency of K-feldspar in three heterogeneous freezing modes. The immersion freezing of K-feldspar was investigated with the cold stage using arrays of nanoliter-size droplets containing aqueous suspension of polydisperse feldspar particles. For contact freezing, the charged droplets of supercooled water were suspended in the laminar flow of the DMA-selected feldspar-containing particles, allowing for determination of freezing probability on a single particle-droplet contact [2]. The nucleation and growth of ice via vapor deposition on the crystalline surfaces of macroscopic feldspar particles have been investigated in the Environmental Scanning Electron Microscope (ESEM) under humidified nitrogen atmosphere. The ice nucleation experiments were supplemented with measurements of effective surface area of feldspar particles and ion chromatography (IC) analysis of the leached framework cations (K+, Na+, Ca2+, Mg2+). In this contribution we focus on the role of surface chemistry influencing the IN efficiency of K-feldspar, in particular the connection between the degree of surface hydroxylation and its ability to induce local structural ordering in the interfacial layer in water molecules (as suggested by recent modeling efforts). We mimic the natural process of feldspar ageing by suspending it in water or weak aqueous solution of carbonic acid for different time periods, from minutes to months, and present its freezing efficiency as a function of time. Our immersion freezing experiments show that ageing have a nonlinear effect on the freezing behavior of feldspar within the investigated temperature range (-40°C to -10°C). On the other hand, deposition nucleation of ice observed in the ESEM reveals clear different pattern

  4. OSL dating of fine-grained quartz from Holocene Yangtze delta sediments

    NASA Astrophysics Data System (ADS)

    Sugisaki, S.; Buylaert, J. P.; Murray, A. S.; Tada, R.; Zheng, H.; Ke, W.; Saito, K.; Irino, T.; Chao, L.; Shiyi, L.; Uchida, M.

    2014-12-01

    Flood events in the Yangtze River are associated with variation in East Asian Summer Monsoon (EASM) precipitation. Understanding the frequency and scale of the EASM precipitation during the Holocene is a key to understanding the mechanism and cyclicity of floods and droughts. Because about 70% of the annual discharge occurs during the flood season, the Yangtze delta sediments provide a good archive of EASM precipitation. In this study, we investigate the possibility of applying OSL dating to establishing high-resolution chronologies for the Yangtze delta sediment cores YD13-1H and G3. The objectives of this study are: (1) test whether fine grained quartz in present day suspended particle matter (SPM) is fully bleached or reset before deposition, (2) where possible, test quartz fine- and coarse-grain OSL dating against radiocarbon shell ages, (3) interpret the sediment transport processes through the differential bleaching of quartz and feldspar OSL signals. We show that the SPM collected from the surface water column of the Yangtze River during the flood season is well-bleached (offset ~60 years). Fine-grained pro-delta sediments are thus potentially a good dosimeter for OSL dating. OSL ages sediment cores indicate a pronounced change in sedimentation rate at ~6 ka and ~2ka. These events are consistent with what is known of the evolution of the Yangtze catchment and delta. The delta began to build at ~6 ka (Zhao et al., 1979), and human activities increased significantly in the catchment at ~2ka (Chen et al., 1985). It is however surprising that the entire top 9 m of sediment only records these two events. The question of whether significant deposition was limited to 2 ka and 6 ka, or whether the record has been disturbed by erosion/reworking remains. These issues are discussed in terms of the reliability of the quartz OSL ages, the degree of bleaching by comparison with polymineral OSL signals, and the relationship of the OSL ages to the sedimentary record.

  5. Open grain boundaries of quartz as fluid pathways in metamorphic rocks

    NASA Astrophysics Data System (ADS)

    Kruhl, J. H.; Wirth, R.; Morales, L. F. G.

    2012-04-01

    TEM analyses coupled with SEM/FIB sequential imaging of quartz from a metamorphic contact aureole and from greenschist-facies regional metamorphism shows that quartz grain boundaries are partly open on the nanometre scale. Three different types of voids occur: (i) up to 500 nm wide open zones parallel to the grain boundaries, (ii) cavities of variable shape and up to micrometer size along the open grain boundaries, and (iii) cone-shaped, nanometre-sized depressions at sites where dislocation lines meet the open grain boundaries. From animations generated with a pile of 100 pictures it is obvious that in three dimensions the larger cavities are interconnected and form channel-like structures which 'migrate' along the grain boundaries and change in dimensions and shape. Consequently, the partly connected open grain boundaries and cavities form a pathway for fluid percolation. Comparison between the measurements and the results of semi-quantitative modelling indicates that the partially open grain boundaries most probably result (i) from reduction of cell dimensions during cooling below the diffusion threshold of quartz (~300°C; Voll, 1976) and (ii) from the fact that this reduction is anisotropic, i.e., different for different crystallographic directions (Kihara, 1990). Preliminary imaging of phase boundaries of quartz, plagioclase, K-feldspar, amphibole and pyroxene and of grain boundaries in calcite show similar features: several hundred nanometre wide open zones parallel to the boundaries and cavities of variable shape and size, often with euhedral segmentation. In addition, newly-grown, partly euhedral crystalline matter of similar composition as the neighbouring minerals may cover the open grain boundaries. These observations indicate locally strong dissolution-precipitation processes within a connected network of open grain and phase boundaries. All these minerals are common in rocks of the middle and lower continental crust, which partly cooled from higher

  6. Age of authigenic K-feldspar in Lower Paleozoic and uppermost Precambrian rocks of the Mississippi Valley area

    SciTech Connect

    Hay, R.L.; Liu, J. . Dept. of Geology); Deino, A. . Geochronology Center); Kyser, T.K. . Dept. of Geology)

    1993-03-01

    Published K-Ar dates of authigenic K-feldspar in Cambrian and Ordovician rocks of the Mississippi Valley area range from 448 to 375 Ma (Late Ordovician to Middle Devonian), suggesting a lengthy episode of K-feldspar authigenesis. Here the authors report an age span of [approximately]464--400 Ma (Middle Ordovician to Early Devonian) for authigenic K-feldspar of two samples from the alteration profile widely developed over Precambrian rocks at the unconformity with Cambrian deposits. This dating was done on 42 to 48 mesh grains of K-feldspar by the laser incremental-heating [sup 40]Ar/[sup 39]Ar method. One sample, from west-central Wisconsin, is from an 8-mm-thick vein formed along a fracture in kaolinitic altered granite. Three grains nearest the fracture yielded plateau ages with a range of [approximately]9 Ma and an average of 430 Ma. Three grains distant from the fracture yielded a similar range of 10 Ma but with an average age of 397 Ma. Thus the grains grew over an extended period from at least [approximately]430 to 400 Ma. A K-Ar date of 411 Ma was obtained from a sample representing the entire thickness of the vein. The other sample, from the St. Francois Mts. of Missouri, is of diabase replaced by K-feldspar. Three grains yielded plateau ages ranging from [approximately]444 to 464 Ma. Oxygen-isotope values of authigenic K-feldspar from lower Paleozoic and uppermost Precambrian rocks range from +19.8 to +22.2[per thousand] and average 21.4[per thousand] (n = 11). These values are compatible with formation of the K-feldspar from similar fluids and comparable temperatures.

  7. Authigenic potassium feldspar: a tracer for the timing of palaeofluid flow in carbonate rocks, Northern Calcareous Alps, Austria

    USGS Publications Warehouse

    Spotl, C.; Kunk, M.J.; Ramseyer, K.; Longstaffe, F.J.

    1998-01-01

    This paper is included in the Special Publication entitled 'Dating and duration of fluid flow and fluid-rock interaction', edited by J. Parnell. Feldspar is a common authigenic constituent in Permian carbonate rocks which occur as tectonically isolated blocks within the evaporitic Haselgebirge melange in the Northern Calcareous Alps (NCA). Coexisting with pyrite, anhydrite, (saddle) dolomite, magnesite, fluorite and calcite, K-feldspar and minor albite record an event of regionally extensive interaction of hot brines with carbonate rocks. Detailed petrographic, crystallographic and geochemical studies reveal a variability in crystal size and shape, Al-Si ordering, elemental and stable isotopic compositions of the K-feldspar, which is only partially consistent with the traditional view of authigenic feldspar as a well-ordered, compositionally pure mineral. 40Ar-39Ar step- heating measurements of authigenic potassium feldspar from several localities yield two age populations, an older one of 145-154 Ma, and a younger one of c.90-97 Ma. Most age spectra reflect cooling through the argon retention temperature interval, which was rapid in some localities (as indicated by plateau ages) and slower in others. Rb-Sr isotope data are more difficult to interpret, because in many K-feldspar samples they are controlled largely by Sr-bearing inclusions. The Jurassic 40Ar-39Ar dates are interpreted as minimum ages of feldspar growth and hence imply that fluid-rock interaction is likely to be simultaneous with or to slightly predate melange formation. Deformation associated with the closure and subduction of the Meliata-Hallstatt ocean south of the NCA during the Upper Jurassic is regarded as the principal geodynamic driving force for both enhanced fluid circulation and melange formation. Some localities were reheated beyond the argon retention temperature for microcline during mid-Cretaceous nappe stacking of the NCA, thus obliterating the older signal.

  8. Millimeter And Submillimeter-Wave Integrated Circuits On Quartz

    NASA Technical Reports Server (NTRS)

    Mehdi, Imran; Mazed, Mohammad; Siegel, Peter; Smith, R. Peter

    1995-01-01

    Proposed Quartz substrate Upside-down Integrated Device (QUID) relies on UV-curable adhesive to bond semiconductor with quartz. Integrated circuits including planar GaAs Schottky diodes and passive circuit elements (such as bandpass filters) fabricated on quartz substrates. Circuits designed to operate as mixers in waveguide circuit at millimeter and submillimeter wavelengths. Integrated circuits mechanically more robust, larger, and easier to handle than planar Schottky diode chips. Quartz substrate more suitable for waveguide circuits than GaAs substrate.

  9. ASR potential of quartz based on expansion values and microscopic characteristics of mortar bars

    NASA Astrophysics Data System (ADS)

    Stastna, Aneta; Sachlova, Sarka; Kuchynova, Marketa; Pertold, Zdenek; Prikryl, Richard

    2016-04-01

    The alkali-silica reaction (ASR) is one of the most damaging factors for concrete structures. Different analytical techniques are used to quantify ASR potential of aggregates. The accelerated mortar bar test (ASTM C1260) in combination with the petrographic examination of aggregates by microscopic techniques belongs to the frequently employed methods. Such a methodical approach enables quantification of the ASR potential, based on the expansion values of accelerated mortar bars; and also to identify deleterious components in aggregates. In this study, the accelerated mortar bar test (ASTM C1260) was modified and combined with the scanning electron microscopy of polished sections prepared from mortar bars. The standard 14-day test period of mortar bars was prolonged to 1-year. ASR potential of aggregates was assessed based on expansion values (both 14-day and 1-year) of mortar bars and microscopic analysis of ASR products (alkali silica gels, microcracks, dissolution gaps) detected in the sections. Different varieties of quartz-rich rocks including chert, quartz meta-greywacke, three types of quartzite and pegmatite were used as aggregate. Only quartz from pegmatite was assessed to be non reactive (14-day expansion of 0.08%, 1-year expansion of 1.25%). Aggregate sections exhibited minor ASR products even after 1-year of mortar bar immersion in 1 M NaOH. Expansion values of the rest of samples exceeded the limit of 0.10% after 14-day test period indicating aggregates as reactive. The highest ASR potential was detected in mortar bars containing chert (14-day expansion of 0.55%, 1-year expansion of 2.70%) and quartz meta-greywacke (14-day expansion of 0.46%, 1-year expansion of 2.41%). The high ASR potential was explained by presence of cryptocrystalline matrix in significant volumes (24 - 65 vol%). Influence of the lengths of the immersion in the alkaline solution was observed mainly in the microstructure of the cement paste and on the extension of ASR products. The

  10. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1996-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy.

  11. Hysteresis in quartz resonators-a review.

    PubMed

    Kusters, J A; Vig, J R

    1991-01-01

    The literature on the frequency versus temperature characteristics of quartz crystal resonators is reviewed. Three papers that deal with frequency versus pressure hysteresis are included, as these may possibly have relevance to frequency versus temperature hysteresis. It is seen that the causes of hysteresis are not well understood. The evidence to date is inconclusive. The mechanisms that can cause hysteresis include: strain changes changes in the quartz, contamination redistribution, oscillator circuitry hysteresis, and apparent hysteresis due to thermal gradients. The results to date seem to indicate that lattice defects are somehow related to thermal hysteresis. Stress relief in the mounting structure can also produce significant hysteresis. As crystal processing techniques have improved. contamination has become less of a problem. PMID:18267585

  12. Multi-quartz-enhanced photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, Yufei; Yu, Xin; Yu, Guang; Li, Xudong; Zhang, Jingbo; Chen, Deying; Sun, Rui; Tittel, Frank K.

    2015-07-01

    A multi-quartz-enhanced photoacoustic spectroscopy (M-QEPAS) sensor system for trace gas detection is reported. Instead of a single quartz tuning fork (QTF) as used in QEPAS technique, a dual QTF sensor platform was adopted in M-QEPAS to increase the signal strength by the addition of the detected QEPAS signals. Water vapor was selected as the target analyte. M-QEPAS realized a 1.7 times signal enhancement as compared to the QEPAS method for the same operating conditions. A minimum detection limit of 23.9 ppmv was achieved for the M-QEPAS sensor, with a calculated normalized noise equivalent absorption coefficient of 5.95 × 10-8 cm-1W/√Hz. The M-QEPAS sensor performance can be further improved when more QTFs are employed or an acoustic micro-resonator architecture is used.

  13. Quartz-superconductor quantum electromechanical system

    NASA Astrophysics Data System (ADS)

    Woolley, M. J.; Emzir, M. F.; Milburn, G. J.; Jerger, M.; Goryachev, M.; Tobar, M. E.; Fedorov, A.

    2016-06-01

    We propose and analyze a quantum electromechanical system composed of a monolithic quartz bulk acoustic wave oscillator coupled to a superconducting transmon qubit via an intermediate L C electrical circuit. Monolithic quartz oscillators offer unprecedentedly high effective masses and quality factors for the investigation of mechanical oscillators in the quantum regime. Ground-state cooling of such mechanical modes via resonant piezoelectric coupling to an L C circuit, which is itself sideband cooled via coupling to a transmon qubit, is shown to be feasible. The fluorescence spectrum of the qubit, containing motional sideband contributions due to the couplings to the oscillator modes, is obtained and the imprint of the electromechanical steady state on the spectrum is determined. This allows the qubit to function both as a cooling resource for, and transducer of, the mechanical oscillator. The results described are relevant to any hybrid quantum system composed of a qubit coupled to two (coupled or uncoupled) thermal oscillator modes.

  14. Alkali metal adsorption on Al(111)

    NASA Astrophysics Data System (ADS)

    Andersen, J. N.; Lundgren, E.; Nyholm, R.; Qvarford, M.

    1993-06-01

    The submonolayer adsorption of Na, K, Rb, and Cs on the Al(111) surface at 100 K and at room temperature is investigated by high resolution core level spectroscopy and low energy electron diffraction. It is found that the first alkali atoms on the surface adsorb at surface defects. At higher coverages, up to approximately one third of the maximum submonolayer coverage, alkali atoms adsorbed at defects coexist with a dispersed phase. At higher coverages island formation is found to occur for the majority of the systems. It is argued that all of the ordered structures formed at room temperature involve a disruption of the Al(111) surface in contrast to the situation at 100 K where the alkali atoms adsorb as adatoms.

  15. SAFE Alkali Metal Heat Pipe Reliability

    NASA Astrophysics Data System (ADS)

    Reid, Robert S.

    2003-01-01

    Alkali metal heat pipes are among the best understood and tested of components for first generation space fission reactors. A flight reactor will require production of a hundred or more heat pipes with assured reliability over a number of years. To date, alkali metal heat pipes have been built mostly in low budget development environments with little formal quality assurance. Despite this, heat pipe test samples suggest that high reliability can be achieved with the care justified for space flight qualification. Fabrication procedures have been established that, if consistently applied, ensure long-term trouble-free heat pipe operation. Alkali metal heat pipes have been successfully flight tested in micro gravity and also have been shown capable of multi-year operation with no evidence of sensitivity to fast neutron fluence up to 1023 n/cm2. This represents 50 times the fluence of the proposed Safe Affordable Fission Engine (SAFE-100) heat pipe reactor core.

  16. Error analysis of quartz crystal resonator applications

    SciTech Connect

    Lucklum, R.; Behling, C.; Hauptmann, P.; Cernosek, R.W.; Martin, S.J.

    1996-12-31

    Quartz crystal resonators in chemical sensing applications are usually configured as the frequency determining element of an electrical oscillator. By contrast, the shear modulus determination of a polymer coating needs a complete impedance analysis. The first part of this contribution reports the error made if common approximations are used to relate the frequency shift to the sorbed mass. In the second part the authors discuss different error sources in the procedure to determine shear parameters.

  17. Saddle-shaped 40Ar /39Ar age spectra from young, microstructurally complex potassium feldspars

    NASA Astrophysics Data System (ADS)

    Zeitler, Peter K.; Fitz Gerald, John D.

    1986-06-01

    A suite of young potassium feldspars show markedly saddle-shaped 40Ar /39Ar age spectra as a result of incorporating 10 -10 to 10 -9 mol/g of excess 40Ar. The minima of these age spectra record reasonable cooling ages, based on the known thermal history and geology of the samples. Acid etching of one sample indicates that excess 40Ar is concentrated near grain margins. The release of a substantial portion of this excess Ar at high temperatures in the laboratory requires that this component be situated in a more retentive site than radiogenic 40Ar. Anion vacancies have been proposed to act in this role in plagioclase, and we speculate that this is so in K-feldspar as well. Such a mechanism would explain the observation that relative to radiogenic 40Ar, excess 40Ar is incorporated at low temperatures in nature but is released at high temperatures in the laboratory. Oxygen diffusion provides an appropriate analogy for this phenomenon, being relatively fast under natural, hydrothermal conditions, but extremely slow in anhydrous environments such as an Ar-extraction system. TEM observations made on two of the samples confirm that their effective grain sizes for diffusion are likely to be on the order of ten microns, due to the presence of such microstructures as incoherent exsolution lamellae, dislocations, and stepped twins. TEM observations also reveal the presence in one sample of orthoclase enclaves in a microcline host.

  18. Rate equations for sodium catalyzed quartz dissolution

    NASA Astrophysics Data System (ADS)

    Rimstidt, J. Donald

    2015-10-01

    Quartz dissolution rate data were fit to an equation that predicts the dissolution flux (J, mol/m2 sec) as a function of temperature (T, K), sodium concentration (mNa+, molal), and hydrogen ion activity (aH+). The same data fit equally well to an equation that expresses the rate as a function of temperature, sodium concentration, and hydroxide ion activity (aOH-) . These equations are more convenient to use than those given by Bickmore et al. (2008) because rates can be predicted without the implementation of a surface speciation model. They predict that at 25 °C quartz dissolves more than 200 times faster in seawater than in pure water. These two equations fit the data just as well as five other equations from Bickmore et al. (2008) that are based on surface species concentrations. All of these rate equations contain information about the reaction mechanism(s) for quartz dissolution but that information is ambiguous because the independent variables used to develop the equations are correlated. This means that rate equations alone cannot be used to infer the dissolution mechanism. Existing surface complexation, surface charge, terrace-ledge-kink, and Lewis acid-base models must be modified and amalgamated in order to develop a reliable model of the reaction mechanism(s).

  19. Quartz-superconductor quantum electromechanical system

    NASA Astrophysics Data System (ADS)

    Woolley, Matt; Emzir, Muhammad; Milburn, Gerard; Jerger, Markus; Goryachev, Maxim; Tobar, Mike; Fedorov, Arkady

    Quartz bulk acoustic wave oscillators support mechanical modes with very high resonance frequencies and extremely high quality factors. As such, they provide an appealing platform for quantum optics experiments with phonons, gravitational wave detection, and tests of quantum mechanics. We propose to cool and measure the motion of a quartz oscillator using a transmon, with the coupling mediated by a tuneable superconducting LC circuit. The mechanical motion (~250MHz) is resonantly coupled to the LC circuit (~250MHz) by a piezoelectric interaction, the LC circuit is coupled to the transmon (~8GHz) via sideband transitions, and there is a smaller direct coupling between the quartz oscillator and the transmon. By driving the transmon on its red sideband, the mechanical and electrical oscillators may be cooled close to their quantum ground state. By observing the fluorescence of the qubit, the occupations of the oscillators may be determined via the motional sidebands they induce. A minimal model of this system consists of a qubit coupled to two oscillators, which are themselves mutually coupled. The steady-state of the system and the qubit fluorescence spectrum are evaluated analytically using a perturbative projection operator technique, and verified numerically.

  20. Diode pumped alkali lasers (DPALs): an overview

    NASA Astrophysics Data System (ADS)

    Krupke, William F.

    2008-05-01

    The concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.

  1. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Koch, M. E.

    1980-01-01

    The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

  2. Alkali-aggregate reaction in concrete containing high-alkali cement and granite aggregate

    SciTech Connect

    Owsiak, Z

    2004-01-01

    The paper discusses results of the research into the influence of high-alkali Portland cement on granite aggregate. The deformation of the concrete structure occurred after 18 months. The research was carried out by means of a scanning electron microscope equipped with a high-energy dispersive X-ray analyzer that allowed observation of unpolished sections of concrete bars exhibiting the cracking pattern typical of the alkali-silica reaction. Both the microscopic observation and the X-ray elemental analysis confirm the presence of alkali-silica gel and secondary ettringite in the cracks.

  3. Recovery of alkali metal constituents from catalytic coal conversion residues

    DOEpatents

    Soung, W.Y.

    In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide to precipitate silicon constituents, the pH of the resultant solution is increased, preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  4. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1995-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

  5. Silica Transport and Cementation in Quartz Aggregates

    NASA Astrophysics Data System (ADS)

    Pebble, C.; Farver, J.; Onasch, C.; Winslow, D.

    2008-12-01

    Silica transport and cementation in quartz aggregates have been experimentally investigated. Starting materials include a natural quartz arenite (Pocono sandstone), sized clasts of synthetic quartz, and sized grains of disaggregated natural sandstones. Experimental charges consisted of amorphous silica powder (~25 mg), AlCl3 powder (~3 mg), 25 wt% NaCl brine solution (~20 mg), and the starting material (~150 mg). The charges were weld-sealed in gold capsules and run in cold-seal pressure vessels at 300°C to 600°C at 150 MPa confining pressure for up to 4 weeks. Detailed calibrations of the furnaces indicate the maximum temperature variation across the length of the sample charges (3-7mm) was <5°C, and typically <3°C. After the experiments, samples were vacuum impregnated with epoxy containing a blue dye and sawn in half along the long axis of the sample charge. The nature and amount of silica transport and cementation in the samples was determined by a combination of Cathodoluminescence (CL), Light Microscopy (LM), and Scanning Electron Microscopy (SEM). Photomosaics of the samples were collected and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement was easily recognized from the quartz grains by the difference in luminescence. The experiments indicate that the presence of amorphous silica results in rapid silica cementation in quartz aggregates (e.g., up to 12% cement by volume in 4 weeks at 450°C). The amount of cementation is a function of substrate type, time, temperature, and ionic strength of the brine. The rate of silica transport through the length of the experimental charge appears to be limited by the silica solubility and its rapid depletion by cementation. Although most of the cement was derived from the amorphous silica, evidence for local dissolution-precipitation was observed. The experiments demonstrate that the mobility of silica, and consequent precipitation of cement, does not require a

  6. Assessment of quality of quartz crystals by EPR and γ-ray diffraction

    NASA Astrophysics Data System (ADS)

    Nienhaus, K.; Stegger, P.; Lehmann, G.; Schneider, J. R.

    1986-03-01

    Natural amethysts from amygdoidal cavities and from fissures as well as synthetic iron-doped quartz crystals of different origins were studied by EPR and γ-ray diffraction. Anisotropic broadening proportional to the slopes of the transitions consistent with a distribution of orientations, most likely due to a mosaic structure, was observed in the EPR spectra of Fe 3+. This broadening was considerably smaller or completely absent in natural amethysts from fissures as well as in a synthetic crystal grown from NH 4F solution. From this broadening average distributions of orientations could be evaluated for substitutional Fe 3+ in good overall agreement with those obtained for the whole crystals by γ-ray diffraction. Thus Fe 3+ is a good probe for the overall quality of the crystals, but the γ-ray diffraction experiments clearly show predominance of a few orientations rather than a random distribution. In the quartz samples of high perfection a hyperfine splitting from an alkali nucleus could be resolved in the EPR spectra of substitutional Fe 3+ at low temperatures and a contribution of vibrations to the minimum linewidths was also observed.

  7. The role of carboxylic acids in albite and quartz dissolution: An experimental study under diagenetic conditions

    SciTech Connect

    Franklin, S.P. ); Hajash, A. Jr.; Tieh, T.T. ); Dewers, T.A. )

    1994-10-01

    Simple water soluble organic acids may promote secondary porosity development in sandstones during diagenesis by increasing feldspar solubility and dissolution rate. To test this hypothesis, Amelia albite and Brazilian hydrothermal quartz were reacted with 0.07 m acetate and 0.07 m acetate-0.005 m oxalate solutions at selected pH values, and distilled water. Pore fluid chemistry was monitored through time at various flow rates to obtain both solubility and dissolution rate data. The experiments were conducted in large volume, semi-static, flow-through systems at 100[degrees]C and 347 bars. These systems simulate subsurface flow rates, low mass water/rock, and high surface area/fluid mass. Acetate and acetate + oxalate solutions significantly increase albite solubility at temperatures, pressures, and pH values typical of diagenetic environments. Albite solubilities increased in acetate and acetate + oxalate solutions by factors of 2 and 3.4, respectively, compared to distilled water. In these same solutions, Al concentrations were [approx] 140 and [approx] 480 times higher than that calculated for kaolinite solubility at the same conditions without organic species. These enhanced solubilities occur at pH values (4.6-4.8) that may overlap with formation waters. In contrast to albite, quartz solubility was essentially identical in all solutions investigated. Dissolution rates in the acid region decreased with increasing pH in the acetate and acetate + oxalate solutions. Slopes of log rate vs. pH curves were [approx] 0.6 for acetate and [approx] 0.3 for acetate + oxalate. Although the effects of acetate on the dissolution rate are small, the effects of oxalate are significant. A rate law valid for albite dissolution at 100[degrees]C, oxalate concentrations to 0.01 m, and pH values ranging from 3.4 to 5.5 is given.

  8. Salts of alkali metal anions and process of preparing same

    DOEpatents

    Dye, James L.; Ceraso, Joseph M.; Tehan, Frederick J.; Lok, Mei Tak

    1978-01-01

    Compounds of alkali metal anion salts of alkali metal cations in bicyclic polyoxadiamines are disclosed. The salts are prepared by contacting an excess of alkali metal with an alkali metal dissolving solution consisting of a bicyclic polyoxadiamine in a suitable solvent, and recovered by precipitation. The salts have a gold-color crystalline appearance and are stable in a vacuum at -10.degree. C. and below.

  9. Evaluation of ASR potential of quartz-rich rocks by alkaline etching of polished rock sections

    NASA Astrophysics Data System (ADS)

    Šachlová, Šárka; Kuchařová, Aneta; Pertold, Zdeněk; Přikryl, Richard

    2015-04-01

    Damaging effect of alkali-silica reaction (ASR) on concrete structures has been observed in various countries all over the World. Civil engineers and real state owners are demanding reliable methods in the assessment of ASR potential of aggregates before they are used in constructions. Time feasible methods are expected, as well as methods which enable prediction of long-term behaviour of aggregates in concrete. The most frequently employed accelerated mortar bar test (AMBT) quantifies ASR potential of aggregates according to the expansion values of mortar bars measured after fourteen days testing period. Current study aimed to develop a new methodical approach facilitating identification and quantification of ASR potential of aggregates. Polished rock sections of quartz and amorphous SiO2 (coming from orthoquartzite, quartz meta-greywacke, pegmatite, phyllite, chert, and flint) were subjected to experimental leaching in 1M NaOH solution at 80°C. After 14 days of alkaline etching, the rock sections were analyzed employing scanning electron microscope combined with energy dispersive spectrometer. Representative areas were documented in back scattered electron (BSE) images and measured using fully-automatic petrographic image analysis (PIA). Several features connected to alkaline etching were observed on the surface of polished rock sections: deep alkaline etching, partial leach-out of quartz and amorphous particles, alkaline etching connected to quartz grain boundaries, and alkaline etching without any connection to grain boundaries. All features mentioned above had significant influence on grey-scale spectrum of BSE images. A specific part of the grey-scale spectrum (i.e. grey-shade 0-70) was characteristic of areas affected by alkaline etching (ASR area). By measuring such areas we quantified the extent of alkaline etching in studied samples. Very good correlation was found between the ASR area and ASR potential of investigated rocks measured according to the

  10. Authigenic quartz in the Upper Freeport coalbed, west- central Pennsylvania

    SciTech Connect

    Ruppert, L.P.

    1985-05-01

    Cathodoluminescence petrography was used to examine quartz grains contained in facies of the Upper Freeport coalbed (Middle Pennsylvanian) of west-central Pennsylvania. Samples included ash concentrates, polished blocks of different lithotypes, and standard petrographic pellets of specific gravity separates of facies channel samples. More than 80% of the quartz in mineral and vitrain-rich bands in the polished blocks do not exhibit cathodoluminescence. In specific gravity separates, 100% of the quartz in the lightest gravity separates did not luminesce. In the heaviest gravity separates, which included shale-parting material, 60% of the quartz did not luminesce. In contrast, in a sample of shale directly overlying the coalbed, more than 90% of the quartz luminesced. On the basis of these data and of other published data, quartz in the Upper Freeport coalbed is interpreted to be authigenic in origin. The authigenic quartz grains are postulated to have been derived from phytoclasts.

  11. Faraday rotation density measurements of optically thick alkali metal vapors

    NASA Astrophysics Data System (ADS)

    Vliegen, E.; Kadlecek, S.; Anderson, L. W.; Walker, T. G.; Erickson, C. J.; Happer, William

    2001-03-01

    We investigate the measurement of alkali number densities using the Faraday rotation of linearly polarized light. We find that the alkali number density may be reliably extracted even in regimes of very high buffer gas pressure, and very high alkali number density. We have directly verified our results in potassium using absorption spectroscopy on the second resonance (4 2S→5 2P).

  12. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  13. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  14. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  15. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for...

  16. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  17. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  18. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  19. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  20. 40 CFR 721.4660 - Alcohol, alkali metal salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alcohol, alkali metal salt. 721.4660... Substances § 721.4660 Alcohol, alkali metal salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance generically identified as alcohol, alkali metal salt (PMN P-91-151)...

  1. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  2. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  3. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  4. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject...

  5. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  6. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  7. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting...

  8. Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

    DOE PAGESBeta

    Deng, Zhi; Mo, Yifei; Ong, Shyue Ping

    2016-03-25

    The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. Here, the scope of this review includes the monovalent lithium- and sodium-ion chemistries that aremore » currently of the most commercial interest.« less

  9. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    DOEpatents

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  10. Terahertz radiation in alkali vapor plasmas

    SciTech Connect

    Sun, Xuan; Zhang, X.-C.

    2014-05-12

    By taking advantage of low ionization potentials of alkali atoms, we demonstrate terahertz wave generation from cesium and rubidium vapor plasmas with an amplitude nearly one order of magnitude larger than that from nitrogen gas at low pressure (0.02–0.5 Torr). The observed phenomena are explained by the numerical modeling based upon electron tunneling ionization.

  11. The Additive Coloration of Alkali Halides

    ERIC Educational Resources Information Center

    Jirgal, G. H.; and others

    1969-01-01

    Describes the construction and use of an inexpensive, vacuum furnace designed to produce F-centers in alkali halide crystals by additive coloration. The method described avoids corrosion or contamination during the coloration process. Examination of the resultant crystals is discussed and several experiments using additively colored crystals are…

  12. Effects of Al/Si ordering on feldspar dissolution: Part II. The pH dependence of plagioclases' dissolution rates

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Min, Yujia; Jun, Young-Shin

    2014-02-01

    The rate of mineral dissolution in an aquatic environment is sensitive to the pH of the contacting solution. The pH dependence of mineral dissolution rate has been interpreted by the Transition State Theory-Surface Complexation Model (TST-SCM) formalism in terms of pH-sensitive variability in surface chemistry. In this study, we provide an alternative interpretation for the experimentally observed nonlinear pH dependence of feldspar dissolution rates. The interpretation is based on a new formalism for feldspar dissolution which, while compatible with the TST-SCM formalism, incorporates the effects of both surface chemistry and bulk chemistry on feldspar dissolution into the quantification of dissolution rate. The pH dependence of dissolution rate varies from one feldspar specimen to another because different TOT linkages within one solid matrix can respond differently to the attack of proton. Our results suggest that the pH dependence of feldspar dissolution rate is not a constant in general, and could be affected by pH, substitutional Al/Si ordering, chemical composition of the specimen, and the relative rapidness of linkage hydrolysis according to different mechanisms. The rate law proposed in this study is able to capture the experimentally observed pH dependence of the dissolution rates of a series of plagioclases, including albite, andesine, labradorite, bytownite, and anorthite. The effectiveness of the newly proposed formalism for feldspar dissolution, hence, suggests that dissolution reactions of minerals are combinations of surface renewal and heterogeneous chemical reactions. The currently widely used TST-SCM-based rate laws can be further improved by taking into account the effects of bulk chemistry and surface renewal in the prediction of mineral dissolution rates. An improved formalism for mineral dissolution will be mineral-specific, and will reflect the effects of the temporal decay in the availability of reactive surface sites as well as the

  13. Ar Ar dating of authigenic K-feldspar: Quantitative modelling of radiogenic argon-loss through subgrain boundary networks

    NASA Astrophysics Data System (ADS)

    Mark, D. F.; Kelley, S. P.; Lee, M. R.; Parnell, J.; Sherlock, S. C.; Brown, D. J.

    2008-06-01

    We have analysed two distinct generations of authigenic K-feldspar in Fucoid Bed sandstones from An-t-Sron and Skiag Bridge, NW Highlands, Scotland, which have experienced post-growth heating to levels in excess of the predicted Ar-closure temperature. Authigenic K-feldspars show microtextural similarities to patch perthites; that is subgrains separated by dislocation-rich boundary networks that potentially act as fast diffusion pathways for radiogenic argon. The two generations of authigenic K-feldspar in the Fucoid Bed sandstones can be distinguished by different microtextural zones, bulk mineral compositions, fluid-inclusion populations, and inferred temperatures and chemistries of parent fluids. Ar-Ar age data obtained using high-resolution ultraviolet laser ablation, show that the first cementing generation is Ordovician and the second cementing generation is Silurian. Modelling of Ar diffusion using subgrain size as the effective diffusion dimension and a simplified tectono-thermal thrust model assuming transient heating of the Fucoid Beds is inconsistent with observed data. Removal of heat from the thrust zone through rapid flushing of heated fluids rather than transient heating can be invoked to explain the observed Ar-Ar ages for both generations of cement. Alternatively, Ar-diffusion modelling using overgrowth thickness as the effective diffusion dimension instead of subgrain size also yields models that are consistent with both the Fucoid Bed palaeothermal maxima and determined Ar-Ar age ages for the two generations of K-feldspar cement. Based on this alternate explanation, we propose a theoretical microtextural model that highlights fundamental differences between the microtextures of deuterically formed patch perthites and authigenic K-feldspars, explaining the apparent robustness of authigenic K-feldspar with respect to Ar-retention.

  14. Hyaline membrane disease, alkali, and intraventricular haemorrhage.

    PubMed Central

    Wigglesworth, J S; Keith, I H; Girling, D J; Slade, S A

    1976-01-01

    The relation between intraventricular haemorrhage (IVH) and hyaline membrane disease (HMD) was studied in singletons that came to necropsy at Hammersmith Hospital over the years 1966-73. The incidence of IVH in singleton live births was 3-22/1000 and of HMD 4-44/1000. Although the high figures were partily due to the large number of low birthweight infants born at this hospital, the incidence of IVH in babies weighing 1001-1500 g was three times as great as that reported in the 1658 British Perinatal Mortality Survey. Most IVH deaths were in babies with HMD, but the higher frequency of IVH was not associated with any prolongation of survival time of babies who died with HMD as compared with the 1958 survey. IVH was seen frequently at gestations of up to 36 weeks in babies with HMD but was rare above 30 weeks' gestation in babies without HMD. This indicated that factors associated with HMD must cause most cases of IVH seen at gestations above 30 weeks. Comparison of clinical details in infants with HMD who died with or without IVH (at gestations of 30-37 weeks) showed no significant differences between the groups other than a high incidence of fits and greater use of alkali therapy in the babies with IVH. During the 12 hours when most alkali therapy was given, babies dying with IVD received a mean total alkali dosage of 10-21 mmol/kg and those dying without IVH 6-34 mmol/kg (P less than 0-001).There was no difference in severity of hypoxia or of metabolic acidosis between the 2 groups. Babies who died with HMD and germinal layer haemorrhage (GLH) without IVH had received significantly more alkali than those who died with HMD alone, whereas survivors of severe respiratory distress syndrome had received lower alkali doses than other groups. It is suggested that the greatly increased death rate from IVH in babies with HMD indicates some alteration of management of HMD (since 1958) as a causative factor. Liberal use of hypertonic alkali solutions is the common factor

  15. Quartz deformation mechanisms during Barrovian metamorphism: Implications from crystallographic orientation of different generations of quartz in pelites

    NASA Astrophysics Data System (ADS)

    Rahimi-Chakdel, A.; Boyle, A. P.; Prior, D. J.

    2006-12-01

    The behaviour of quartz during metamorphism is studied based on two case studies from the Barrovian terrains of Sulitjelma in arctic Scandinavia and Loch Tay in the Central Highlands Dalradian of Scotland. Both terrains preserve evidence for metamorphism in pelites involving nucleation and growth of garnet at different times in the deformation history. Data are presented on the size, shape and crystallographic orientation of quartz preserved as inclusions in garnet and as grains in the surrounding matrix. While quartz-grains remain small and dispersed between mica grains, deformation appears to be dominated by grain-boundary sliding accommodated by dissolution-precipitation. At amphibolite facies, textural coarsening occurs by dissolution of small quartz grains and growth of larger quartz grains, coupled with segregation of quartz from mica. As a result, quartz deforms by dislocation creep, developing crystallographic preferred orientations (CPO) consistent with both coaxial and non-coaxial strain. Quartz CPOs with <0001> axes lying parallel to foliation and stretching direction are commonly developed, and best explained by mechanical rotation of inequant (detrital?) quartz grains. There is no evidence for selective entrapment of quartz inclusions in garnet on the basis of quartz crystallographic orientation.

  16. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Jørgen Kjøll, Hans; Viola, Giulio; Menegon, Luca; Sørensen, Bjørn

    2015-04-01

    A coarse grained, statically crystallized quartz vein with a random CPO, embedded in a phyllonitic matrix, was studied by optical microscopy, SEM imaging and EBSD to gain insights into the processes of strain localization in quartz deformed under low greenschist facies conditions at the frictional-viscous transition. The vein is located in a high strain zone at the front of an imbricate stack of Caledonian age along the northwesternmost edge of the Repparfjord Tectonic Window in northern Norway. The vein was deformed within the Nussirjavrri Fault Zone (NFZ), an out-of-sequence thrust with a phyllonitic core characterized by a ramp-flat-ramp geometry, NNW plunging stretching lineations and top-to-the SSE thrusting kinematics. Deformation conditions are typical of the frictional-viscous transition. The phyllonitic core formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation, related to the development of a mesoscopic pervasive extensional crenulation cleavage, was accommodated within the vein initially by basal slip of suitably oriented quartz crystals, which produced e.g. undulose extinction, extinction bands and bulging grain boundaries. In the case of misoriented quartz crystals, however, glide-accommodated dislocation creep resulted soon inefficient and led to localized dislocation tangling and strain hardening. In response to 1) hardening, 2) progressive increase of fluid pressure within the actively deforming vein and 3) increasing competence contrast between the vein and the surrounding weak, foliated phyllonitic fault core, quartz crystals began to deform frictionally along specific lattice planes oriented optimally with respect to the imposed stress field. Microfaulting generated small volumes of gouge along

  17. An Experimental Study of Lithium Isotope Partitioning Among Quartz, Muscovite, and Fluid

    NASA Astrophysics Data System (ADS)

    Lynton, S. J.; Walker, R. J.; Candela, P. A.

    2002-05-01

    Preliminary results from an experimental study suggest that lithium isotopes may serve as an indicator of magmatic hydrothermal processes in felsic environments, such as granitic pegmatites and porphyry-type ore deposits. The experiments were carried out with natural (pegmatitic) specimens of quartz and muscovite and with a chloride-bearing aqueous fluid at 400-500° C and 50-100 MPa. Lithium was introduced into the experimental charges through the fluid, which also contains KCl and HCl (K/Li/H = 100/10/1) and is 1M in total chloride. Two other phases (K-feldspar and phlogopite) were included in the charges to permit coupled substitutions by Li + Al and by Li + Mg into Qz and Ms. In contrast with experiments in other isotope systems (eg., O), Li partitioning experiments require allowance for coupled substitutions because some crystallographic sites only become available to Li through coupled substitutions and because the chemical potentials of components necessary for coupled substitutions must be fixed to define fully the thermodynamic conditions of Li partitioning. In two of the experiments a 6Li spike was used to prepare the fluid to magnify the shifts in Li isotopic compositions among run products. The experiments were conducted for 15-60 days under argon pressure with Pt capsules, which were loaded into Inconel 625 cold seal vessels. The experimental design permits simultaneous determination of isotopic fractionation and elemental partitioning by Li among quartz, muscovite and the fluid. Lithium isotopic compositions were determined by thermal ionization mass spectrometry with a triple-filament technique, in which samples are evaporated from side filaments as a phosphate and Li ions are measured directly by the peak-jumping method. Replicate analyses and duplicate experiments indicate reproduceability within approximately +/-1-2‰ . Li concentrations were determined by isotope dilution. For the 500° C runs, the preliminary results provide some indications

  18. Kinetics of the coesite to quartz transformation

    USGS Publications Warehouse

    Mosenfelder, J.L.; Bohlen, S.R.

    1997-01-01

    The survival of coesite in ultrahigh-pressure (UHP) rocks has important implications for the exhumation of subducted crustal rocks. We have conducted experiments to study the mechanism and rate of the coesite ??? quartz transformation using polycrystalline coesite aggregates, fabricated by devitrifying silica glass cylinders containing 2850H/106 Si at 1000??C and 3.6 GPa for 24h. Conditions were adjusted following synthesis to transform the samples at 700-1000??C at pressures 190-410 MPa below the quartz-coesite equilibrium boundary. Reaction proceeds via grain-boundary nucleation and interface-controlled growth, with characteristic reaction textures remarkably similar to those seen in natural UHP rocks. We infer that the experimental reaction mechanism is identical to that in nature, a prerequisite for reliable extrapolation of the rate data. Growth rates obtained by direct measurement differ by up to two orders of magnitude from those estimated by fitting a rate equation to the transformation-time data. Fitting the rates to Turnbull's equation for growth therefore yields two distinct sets of parameters with similar activation energies (242 or 269 kJ/mol) but significantly different pre-exponential constants. Extrapolation based on either set of growth rates suggests that coesite should not be preserved on geologic time scales if it reaches the quartz stability field at temperatures above 375-400??C. The survival of coesite has previously been linked to its inclusion in strong phases, such as garnet, that can sustain a high internal pressure during decompression. Other factors that may play a crucial role in preservation are low fluid availability - possibly even less than that of our nominally "dry" experiments - and the development of transformation stress, which inhibits nucleation and growth. These issues are discussed in the context of our experiments as well as recent observations from natural rocks. ?? 1997 Elsevier Science B.V.

  19. Evidence for 26Al in Feldspars from the H4 Chondrite Ste. Marguerite

    NASA Astrophysics Data System (ADS)

    Zinner, E.; Gopel, C.

    1992-07-01

    One of the important questions for the history of the early solar system is whether or not there was enough ^26Al to melt small planetary bodies through the heat released by its decay. Although there is ample evidence for the existence of live ^26Al in refractory inclusions (Wasserburg and Papanastassiou, 1982; Hutcheon, 1982; Podosek et al., 1991), CAIs are special objects with peculiar properties and their Al is not necessarily representative of that of their host meteorites nor the early solar systems. Furthermore, some inclusions do not show any evidence for ^26Al (Wasserburg and Papanastassiou, 1982; Ireland, 1990; Virag et al., 1991), raising the possibility of ^26Al heterogeneity. The only previous observation of ^26Mg excesses attributed to the decay of ^26Al outside of CAIs was in an igneous clast from Semarkona (Hutcheon and Hutchison, 1989) leading to the conclusion that ^26Al indeed could have been a heat source for planetary melting. We have measured Al-Mg in plagioclase grains from the H4 chondrite Ste. Marguerite by ion microprobe mass spectrometry. Feldspars from H4 chondrites are good samples for addressing the problem of ^26Al as heat source because most Al resides in this phase and some H4s experienced fast cooling (Pellas and Storzer, 1981); in fact, the possibility of live ^26Al in feldspars from H4 chondrites that cooled fast has been predicted by Pellas and Storzer (1981). Furthermore, extremely precise absolute Pb/Pb ages exist for these meteorites (Gopel et al., 1991). Figure 1 shows the measurements on five feldspar crystals. All show ^26Mg excesses. A fit through the data points and the normal ^26Mg/^24Mg ratio of 0.13962 obtained from Lake County plagioclase measured under the same instrumental conditions as the Ste. Marguerite samples yields a (^26Al/^27Al)(sub)0 ratio of (2.0 +- 0.6) x 10^-7. If interpreted chronologically this ratio dates the retention of radiogenic ^26Mg in Ste. Marguerite feldspar to 5.6 +- 0.4 Ma after the

  20. Laboratory measurements of upwelled radiance and reflectance spectra of Calvert, Ball, Jordan, and Feldspar soil sediments

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Usry, J. W.; Witte, W. G.; Gurganus, E. A.

    1977-01-01

    An effort to investigate the potential of remote sensing for monitoring nonpoint source pollution was conducted. Spectral reflectance characteristics for four types of soil sediments were measured for mixture concentrations between 4 and 173 ppm. For measurements at a spectral resolution of 32 mm, the spectral reflectances of Calvert, Ball, Jordan, and Feldspar soil sediments were distinctly different over the wavelength range from 400 to 980 nm at each concentration tested. At high concentrations, spectral differences between the various sediments could be detected by measurements with a spectral resolution of 160 nm. At a low concentration, only small differences were observed between the various sediments when measurements were made with 160 nm spectral resolution. Radiance levels generally varied in a nonlinear manner with sediment concentration; linearity occurred in special cases, depending on sediment type, concentration range, and wavelength.

  1. Elemental content of feldspar from Eastern Desert, Egypt, determined by INAA and XRF.

    PubMed

    El-Taher, A

    2010-06-01

    Instrumental neutron activation analysis (INAA) and HPGe detector gamma-spectroscopy were used to determine a total of 16 elements qualitatively and quantitatively for the first time from feldspar rock samples collected from Gabel El Dubb, Eastern desert, Egypt. The elements determined are (Na, Mg, K, Sc, Ga, Cr, Fe, Co, Zn, Nb, Ba, Ce, Eu, Hf, Th and U). The samples were properly prepared together with their standard reference material and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor at a neutron flux of 7x10(11)n/cm(2)s. XRF was also used. Comparison of the results obtained by both techniques showed good agreement for such elements as K, Na, Fe, Mg, Ba and Cr. PMID:20185321

  2. Spherical quartz crystals investigated with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Pereira, N. R.; Macrander, A. T.; Hill, K. W.; Baronova, E. O.; George, K. M.; Kotick, J.

    2015-10-01

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal's x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal's local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background.

  3. Spherical quartz crystals investigated with synchrotron radiation.

    PubMed

    Pereira, N R; Macrander, A T; Hill, K W; Baronova, E O; George, K M; Kotick, J

    2015-10-01

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal's x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal's local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background. PMID:26520963

  4. Environmental sensitivities of quartz crystal oscillators

    NASA Technical Reports Server (NTRS)

    Walls, Fred L.

    1990-01-01

    The frequency, amplitude, and noise of the output signal of a quartz crystal controlled oscillator is affected by a large number of environmental effects. The physical basis for the sensitivity of precision oscillators to temperature, humidity, pressure, vibration, magnetic field, electric field, load, and radiation is discussed. The sensitivity of crystal oscillators to radiation is a very complex topic and poorly understood. Therefore only a few general results are mentioned. The sensitivity to most external influences often varies significantly from one oscillator type to another and from one unit of given type to another. For a given unit, the sensitivity to one parameter often depends on the value of other parameters and history.

  5. Control of electroosmosis in coated quartz capillaries

    NASA Technical Reports Server (NTRS)

    Herren, Blair J.; Van Alstine, James; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

    1987-01-01

    The effectiveness of various coatings for controlling the electroosmotic fluid flow that hinders electrophoretic processes is studied using analytical particle microelectrophoresis. The mobilities of 2-micron diameter glass and polystyrene latex spheres (exhibiting both negative and zero effective surface charge) were measured in 2-mm diameter quartz capillaries filled with NaCl solutions within the 3.5-7.8 pH range. It is found that capillary inner surface coatings using 5000 molecular weight (or higher) poly(ethylene glycol): significantly reduced electroosmosis within the selected pH range, were stable for long time periods, and appeared to be more effective than dextran, methylcellulose, or silane coatings.

  6. Calorimetric thermobarometry of experimentally shocked quartz

    NASA Technical Reports Server (NTRS)

    Ocker, Katherine D.; Gooding, James L.; Hoerz, Friedrich

    1994-01-01

    Structural damage in experimentally shock-metamorphosed, granular quartz is quantitatively measurable by differential scanning calorimetry (DSC). Shock-induced loss of crystallinity is witnessed by disappearance of the alpha/beta phase transformation and evolution of a broad endoenthalpic strain peak at 650-900 K. The strain-energy peak grows rapidly at less than 10 GPa but declines with increasing shock pressure; it approaches zero at 32 GPa where vitrification is extensive. Effects of grain size and post-shock thermal history must be better understood before calorimetric thermobarometry of naturally shocked samples becomes possible.

  7. Suspended polymer nanobridge on a quartz resonator

    NASA Astrophysics Data System (ADS)

    Yun, Minhyuk; Lee, Seongjae; Yim, Changyong; Jung, Namchul; Thundat, Thomas; Jeon, Sangmin

    2013-07-01

    A chemical vapor sensor based on a free-standing polystyrene (PS) nanofilm suspended between the tines of a quartz tuning fork (QTF) is demonstrated. Exposure to ethanol vapor decreased the modulus of the PS membrane, which resulted in a decrease in the resonance frequency of the QTF as a function of ethanol concentration. The suspended PS membrane structure on the QTF allowed gas molecules to diffuse into the membrane from both the top and bottom allowing faster response. The QTF response time was found to be 6.5 times faster than the response time of a conventional PS film-coated resonator sensor.

  8. Immunosensors using a quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shigeru; Aizawa, Hidenobu; Tozuka, Mitsuhiro; Nakamura, Miki; Park, Jong-Won

    2003-11-01

    Better analytical technology has been demanded for accurate and rapid determination of trace amounts of chemical compounds, such as marker proteins for disease or endocrine disrupters like dioxin, which might be contained in blood, food and the environment. The study of immunosensors using a quartz crystal microbalance (QCM) has recently focused on conventional detection methods for the determination of chemical compounds together with the development of reagents and processes. This paper introduces the principle of the detection method of QCM immunosensors developed at AIST and its application to the detection of trace amounts of chemical compounds.

  9. Spherical quartz crystals investigated with synchrotron radiation

    SciTech Connect

    Pereira, N. R.; Macrander, A. T.; Hill, K. W.; Baronova, E. O.; George, K. M.; Kotick, J.

    2015-10-15

    The quality of x-ray spectra and images obtained from plasmas with spherically bent crystals depends in part on the crystal’s x-ray diffraction across the entire crystal surface. We employ the energy selectivity and high intensity of synchrotron radiation to examine typical spherical crystals from alpha-quartz for their diffraction quality, in a perpendicular geometry that is particularly convenient to examine sagittal focusing. The crystal’s local diffraction is not ideal: the most noticeable problems come from isolated regions that so far have failed to correlate with visible imperfections. Excluding diffraction from such problem spots has little effect on the focus beyond a decrease in background.

  10. Physics and chemistry of alkali-silica reactions

    SciTech Connect

    Diamond, S.; Barneyback, R.S. Jr.; Struble, L.J.

    1981-01-01

    The philosophy underlying recent research on alkali-silica reactions is reviewed and illustrations of recent results are provided. It has been possible to follow the kinetics of the chemical reaction between dissolved alkalis and opal in mortars by monitoring the rate at which alkalis are removed from the pore solutions of reacting mortars. Studies of the expansion behavior of synthetic alkali silica gels under controlled conditions were carried out and show no obvious correlation to chemical composition. The alkali reaction in mortars was found to produce changes in the appearance of opal grains documentable by the use of a scanning electron microscope.

  11. Calcium-Alkali Syndrome in the Modern Era

    PubMed Central

    Patel, Ami M.; Adeseun, Gbemisola A.; Goldfarb, Stanley

    2013-01-01

    The ingestion of calcium, along with alkali, results in a well-described triad of hypercalcemia, metabolic alkalosis, and renal insufficiency. Over time, the epidemiology and root cause of the syndrome have shifted, such that the disorder, originally called the milk-alkali syndrome, is now better described as the calcium-alkali syndrome. The calcium-alkali syndrome is an important cause of morbidity that may be on the rise, an unintended consequence of shifts in calcium and vitamin D intake in segments of the population. We review the pathophysiology of the calcium-alkali syndrome. PMID:24288027

  12. Deformation of ⊥m single quartz crystals

    NASA Astrophysics Data System (ADS)

    Krasner, P.; Holyoke, C. W., III; Kronenberg, A. K.

    2015-12-01

    The rheology of quartz deformed by dislocation creep is essential to understanding the strength of the mid to lower continental crust. Our current understanding of quartz rheology is derived primarily from studies of polycrystalline quartz and little is known about the temperature, strain rate, or water dependence of the individual quartz slip systems. In order to better understand the rheology of quartz slip systems, we have deformed synthetic quartz single crystals with the prism oriented at 45° to the compression direction (⊥m orientation). We converted the gel-type water found in synthetic quartz crystals to free water fluid inclusions, similar to water observed in milky quartz crystals, by annealing the crystals at 900°C/0.1 MPa for 24 hours. The single crystals were deformed at a confining pressure of 1.5 GPa with temperatures of 850 to 1000°C and strain rates of 10-6 to 10-4/s. FTIR measurements of water concentrations in the starting material, annealed synthetic crystals and deformed synthetic quartz crystals indicate that the water concentrations (125-300 H/106Si) are not affected by the annealing process or deformation. However, the spectra in the annealed and deformed samples are similar to those of natural milky quartz rather than those of synthetic quartz. Results of temperature and strain rate stepping experiments indicate that the strength of the crystals decreases with increasing temperature and/or decreasing strain rate. Undulatory extinction is the predominant microstructure observed in deformed samples, which is consistent with deformation by dislocation creep. The strength of the ⊥m oriented quartz crystals deformed in this study with free water is greater than those of the studies of synthetic quartz with gel type water (Linker and Kirby, 1981 and Muto et al., 2011).

  13. Alkali metal recovery from carbonaceous material conversion process

    DOEpatents

    Sharp, David W.; Clavenna, LeRoy R.; Gorbaty, Martin L.; Tsou, Joe M.

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced in the gasifier or similar reaction zone, alkali metal constitutents are recovered from the particles by withdrawing and passing the particles from the reaction zone to an alkali metal recovery zone in the substantial absence of molecular oxygen and treating the particles in the recovery zone with water or an aqueous solution in the substantial absence of molecular oxygen. The solution formed by treating the particles in the recovery zone will contain water-soluble alkali metal constituents and is recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preventing contact of the particles with oxygen as they are withdrawn from the reaction zone and during treatment in the recovery zone avoids the formation of undesirable alkali metal constituents in the aqueous solution produced in the recovery zone and insures maximum recovery of water-soluble alkali metal constituents from the alkali metal residues.

  14. Alkali element background reduction in laser ICP-MS

    NASA Astrophysics Data System (ADS)

    Magee, C. W., Jr.; Norris, C. A.

    2014-11-01

    Alkali backgrounds in laser ablation ICP-MS analyses can be enhanced by electron-induced ionization of alkali contamination on the skimmer cone, reducing effective detection limits for these elements. Traditionally, this problem is addressed by isolating analyses of high alkali materials onto a designated cone set, or by operating the ICP-MS in a "soft extraction" mode, which reduces the energy of electrons repelled into the potentially contaminated sampling cone by the extraction field. Here we present a novel approach, where we replace the traditional alkali glass tuning standards with synthetic low-alkali glass reference materials. Using this vitreous tuning solution, we find that this approach reduces the amount of alkali contamination produced, halving backgrounds for the heavy alkali elements without any change to analytical procedures. Using segregated cones is still the most effective method for reducing lithium backgrounds, but since the procedures are complimentary both can easily be applied to the routine operations of an analytical lab.

  15. Alkali element background reduction in laser ICP-MS

    NASA Astrophysics Data System (ADS)

    Magee, C. W., Jr.; Norris, C. A.

    2015-03-01

    Alkali backgrounds in laser ablation ICP-MS analyses can be enhanced by electron-induced ionisation of alkali contamination on the skimmer cone, reducing effective detection limits for these elements. Traditionally, this problem is addressed by isolating analyses of high-alkali materials onto a designated cone set, or by operating the ICP-MS in a "soft extraction" mode, which reduces the energy of electrons repelled into the potentially contaminated sampling cone by the extraction field. Here we present a novel approach, where we replace the traditional alkali glass tuning standards with synthetic low-alkali glass reference materials. Using this vitreous tuning solution, we find that this approach reduces the amount of alkali contamination produced, halving backgrounds for the heavy alkali elements without any change to analytical procedures. Using segregated cones is still the most effective method for reducing lithium backgrounds, but since the procedures are complimentary, both can easily be applied to the routine operations of an analytical lab.

  16. Discovery of coesite and shocked quartz associated with the upper Eocene cpx spherule layer

    NASA Technical Reports Server (NTRS)

    Liu, S.; Kyte, T.; Glass, B. P.

    2002-01-01

    At least two major impact ejecta layers have been discovered in upper Eocene strata. The upper layer is the North American microtektite layer. lt consists tektite fragments, microtektites, and shocked mineral grains (e.g., quartz and feldspar with multiple sets of PDFs, coesite and reidite (a high-pressure polymorph of zircon)). The slightly older layer contains clinopyroxene-bearing (cpx) spherules and microtektites associated with an Ir anomaly. The North American tektite layer may be derived from the Chesapeake Bay impact structure, and the cpx spherule layer may from the Popigai impact crater. A cpx spherule layer associated with a positive Ir anomaly was recently found at ODP Site 709, western Indian Ocean. A large sample (Hole 709C, core 31, section 4, 145-150 cm), originally used for a study of interstitial water by shipboard scientists, was acquired for the purpose of recovering a large number of spherules for various petrographic and geochemical studies. A split of the sample (50.35 g) was disaggregated and wet-sieved. More than 17,000 cpx spherules and several hundred microtektites (larger than 125 microns) were recovered from the sample. Rare white opaque grains were observed in the 125-250 micron size fraction after removal of the carbonate component using dilute HCI. Seven of the white opaque grains were X-rayed using a Gandolfi camera and six were found to be coesite (probably mixed with lechatelierite). Eighty translucent colorless grains from the 63-125 micron size fraction were studied with a petrographic microscope. Four of the grains exhibit one to two sets of planar deformation features (PDFs). The only other possible known occurrence of shocked minerals associated with the cpx spherule layer is at Massignano, Italy, where pancake-shaped clay spherules (thought to be diagenetically altered cpx spherules are associated with a positive Ir anomaly and Ni- rich spinel crystals. Shocked quartz grains with multiple sets of PDFs also occur at this site

  17. Universal elastic-hardening-driven mechanical instability in α-quartz and quartz homeotypes under pressure.

    PubMed

    Dong, Juncai; Zhu, Hailiang; Chen, Dongliang

    2015-01-01

    As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably α-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of α-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the transition through Born criteria B3. However, by using density-functional theory, we surprisingly found that both C44 and C66 in α-quartz exhibit strong nonlinearity under compression and the Born criteria B3 vanishes dominated by stiffening of C14, instead of by decreasing of C44. Further studies of archetypal quartz homeotypes (GeO2 and AlPO4) repeatedly reproduced the same elastic-hardening-driven mechanical instability, suggesting a universal feature of this family of crystals and challenging the long-standing idea that negative pressure derivatives of individual elastic moduli can be interpreted as the precursor effect to an intrinsic structural instability preceding PIA. The implications of this elastic anomaly in relation to the dispersive softening of the lowest acoustic branch and the possible transformation mechanism were also discussed. PMID:26099720

  18. Universal elastic-hardening-driven mechanical instability in α-quartz and quartz homeotypes under pressure

    PubMed Central

    Dong, Juncai; Zhu, Hailiang; Chen, Dongliang

    2015-01-01

    As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably α-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of α-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the transition through Born criteria B3. However, by using density-functional theory, we surprisingly found that both C44 and C66 in α-quartz exhibit strong nonlinearity under compression and the Born criteria B3 vanishes dominated by stiffening of C14, instead of by decreasing of C44. Further studies of archetypal quartz homeotypes (GeO2 and AlPO4) repeatedly reproduced the same elastic-hardening-driven mechanical instability, suggesting a universal feature of this family of crystals and challenging the long-standing idea that negative pressure derivatives of individual elastic moduli can be interpreted as the precursor effect to an intrinsic structural instability preceding PIA. The implications of this elastic anomaly in relation to the dispersive softening of the lowest acoustic branch and the possible transformation mechanism were also discussed. PMID:26099720

  19. Insitu Calibration of Quartz Crystal Microbalances

    NASA Technical Reports Server (NTRS)

    Albyn, Keith; Burns, Dewit

    2006-01-01

    Computer models that predict the rate at which molecular contamination will deposit on optical surfaces typically use outgassing source terms, measured with quartz crystal microbalances, as a basis for the prediction. The American Society of Testing and Materials, Standard Test Method for Contamination Outgassing Characteristics of Spacecraft Materials (Method E-1559), is probably the best know technique used by the aerospace community to measure the outgassing rates or source terms of materials. A simple method for the insitu calibration of quartz crystal microbalances, based on the heat of enthalphy of Adipic Acid, has been developed and demonstrated by the Marshall Space Flight Center, Environmental Effects Group. The calibration has been demonstrated over a sample temperature range of 25 to 66 degrees Celsius and deposition rates of 7 x 10 (exp -11) grams/cm(sup 2)-s and greater, for several measurement system configurations. This calibration technique is fully compatible with the American Society for Testing and Materials, Method E-1559, as well as other methodology. The calibration requires no modification of outgassing facilities employing an effusion cell and does not degrade the performance or function of typical vacuum systems.

  20. Shock characterization of quartz phenolic composite

    SciTech Connect

    Weirick, L.J.; Chhabildas, L.C.

    1994-03-01

    Goal was to obtain dynamic mechanical property data on a quartz phenolic (abbreviated QP) composite. Shock loading and shock release measurements have been conducted using impact techniques utilizing both a light-gas gun and a powder gun at impact pressures up to 20 GPa. The primary diagnostic tool used was a velocity interferometer. The data analysis includes Hugoniot measurements to give both pressure-particle velocity and shock velocity-particle velocity relationships; spall measurements to determine the fracture stress at which the material spells; and attenuation measurements to determine the shock attenuation with material thickness. The QP Hugoniot relationship was found to be significantly different than that of a phenolic without a filler material indicating that the impedance of the QP used in this investigation was higher. The spall strength was measured to be {approximately}0.075 GPa, similar to nonfilled phenolic, which indicated that the presence of quartz fibers was not contributing to the fracture strength. The material was found to attenuate an imposed shock of approximately 6.3 GPa pressure and 0.18 {mu}s to 50% of the initial impact value after a propagation distance of 7mm.

  1. Developments in alkali-metal atomic magnetometry

    NASA Astrophysics Data System (ADS)

    Seltzer, Scott Jeffrey

    Alkali-metal magnetometers use the coherent precession of polarized atomic spins to detect and measure magnetic fields. Recent advances have enabled magnetometers to become competitive with SQUIDs as the most sensitive magnetic field detectors, and they now find use in a variety of areas ranging from medicine and NMR to explosives detection and fundamental physics research. In this thesis we discuss several developments in alkali-metal atomic magnetometry for both practical and fundamental applications. We present a new method of polarizing the alkali atoms by modulating the optical pumping rate at both the linear and quadratic Zeeman resonance frequencies. We demonstrate experimentally that this method enhances the sensitivity of a potassium magnetometer operating in the Earth's field by a factor of 4, and we calculate that it can reduce the orientation-dependent heading error to less than 0.1 nT. We discuss a radio-frequency magnetometer for detection of oscillating magnetic fields with sensitivity better than 0.2 fT/ Hz , which we apply to the observation of nuclear magnetic resonance (NMR) signals from polarized water, as well as nuclear quadrupole resonance (NQR) signals from ammonium nitrate. We demonstrate that a spin-exchange relaxation-free (SERF) magnetometer can measure all three vector components of the magnetic field in an unshielded environment with comparable sensitivity to other devices. We find that octadecyltrichlorosilane (OTS) acts as an anti-relaxation coating for alkali atoms at temperatures below 170°C, allowing them to collide with a glass surface up to 2,000 times before depolarizing, and we present the first demonstration of high-temperature magnetometry with a coated cell. We also describe a reusable alkali vapor cell intended for the study of interactions between alkali atoms and surface coatings. Finally, we explore the use of a cesium-xenon SERF comagnetometer for a proposed measurement of the permanent electric dipole moments (EDMs

  2. Design of a tuning-fork gyro made of quartz

    NASA Astrophysics Data System (ADS)

    Jia, Yubin; Sun, Yunan; Qin, BingKun; Cui, Fang; Chen, Gang

    1998-08-01

    Based on piezoelectric effect of quartz, a design of tuning- fork gyroscopes made of quartz was presented in this paper. The gyroscope is a kind of micro-machined quartz angular rate sensor. Its structure is similar to a tuning fork in quartz watch. In the gyroscope, the piezoelectric effect in quartz is used both to excite a reference vibration in the plane of tuning fork and to detect a vibration normal to this plane due to an externally applied rotation. The amplitude of the second vibration is directly proportional to the angular velocity of the applied rotation. In contrast to ordinary types of tuning fork gyroscopes, this gyroscope uses a single piece of quartz, the sensor element is of a design in which the only vibrationally, active areas are the tines of the tuning fork.

  3. The role of deformation on trace element solubility in quartz: Observations from naturally deformed quartz-rich rocks and experimentally deformed Ti-doped synthetic quartz aggregates

    NASA Astrophysics Data System (ADS)

    Nachlas, W.; Whitney, D. L.; Teyssier, C.; Seaton, N. C.; Hirth, G.

    2011-12-01

    Recent advances in resolving the significance of trace element solubility (e.g., Ti) in quartz have largely focused on reconstructing the P-T-X conditions of equilibration. The calibration of Ti in quartz thermometry (TitaniQ) and the refined precision of analytical instrumentation for in-situ quantitative analysis make this a very effective technique for thermobarometric reconstructions of geologic events. However, the incorporation of trace impurities in the quartz lattice is likely to be affected by deformation, as crystal plasticity may influence the mobility of trace elements. To investigate the role of dynamic recrystallization on the accommodation of changing trace element solubility in quartz, this study combines measurements of trace element concentrations and distribution in naturally deformed quartz with high P-T deformation experiments of trace element doped synthetic quartz aggregates. Measurements of the trace element concentration of quartz from an extensional shear zone in the North American Cordillera provide insight to the behavior of trace elements during dynamic recrystallization associated with retrograde cooling and exhumation. Rutile-bearing quartzite mylonites from the Thor-Odin core complex, British Columbia, were selected for analysis based on the ability to determine Ti activity, the identification of a suitable protolith, and the existence of stable isotope thermometry that allows comparison with independent thermometers. High resolution quantitative analysis reveals systematic compositional variability: the interior of deformed quartz grains preserves a higher Ti concentration than the adjacent rim of the grain. This correlation between microstructural domain and trace element distribution suggests a relationship between the solubility of trace impurities and the mechanism of dynamic recrystallization in quartz. To experimentally investigate the role of deformation on the solubility of trace elements in quartz, synthetic quartz

  4. Effect of alkali lignins with different molecular weights from alkali pretreated rice straw hydrolyzate on enzymatic hydrolysis.

    PubMed

    Li, Yun; Qi, Benkun; Luo, Jianquan; Wan, Yinhua

    2016-01-01

    This study investigated the effect of alkali lignins with different molecular weights on enzymatic hydrolysis of lignocellulose. Different alkali lignins fractions, which were obtained from cascade ultrafiltration, were added into the dilute acid pretreated (DAP) and alkali pretreated (AP) rice straws respectively during enzymatic hydrolysis. The results showed that the addition of alkali lignins enhanced the hydrolysis and the enhancement for hydrolysis increased with increasing molecular weights of alkali lignins, with maximum enhancement being 28.69% for DAP and 20.05% for AP, respectively. The enhancement was partly attributed to the improved cellulase activity, and filter paper activity increased by 18.03% when adding lignin with highest molecular weight. It was found that the enhancement of enzymatic hydrolysis was correlated with the adsorption affinity of cellulase on alkali lignins, and the difference in surface charge and hydrophobicity of alkali lignins were responsible for the difference in affinity between cellulase and lignins. PMID:26496216

  5. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, B.L.

    1996-11-19

    An optical furnace for annealing a process wafer is disclosed comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy. 5 figs.

  6. Active feedback cooling of massive electromechanical quartz resonators

    SciTech Connect

    Jahng, Junghoon; Lee, Manhee; Stambaugh, Corey; Bak, Wan; Jhe, Wonho

    2011-08-15

    We present a general active feedback cooling scheme for massive electromechanical quartz resonators. We cool down two kinds of macrosized quartz tuning forks and find several characteristic constants for this massive quartz-resonator feedback cooling, in good agreement with theoretical calculations. When combined with conventional cryogenic techniques and low-noise devices, one may reach the quantum sensitivity for macroscopic sensors. This may be useful for high sensitivity measurements and for quantum information studies.

  7. Mineral resource of the month: cultured quartz crystal

    USGS Publications Warehouse

    U.S. Geological Survey

    2008-01-01

    The article presents information on cultured quartz crystals, a mineral used in mobile phones, computers, clocks and other devices controlled by digital circuits. Cultured quartz, which is synthetically produced in large pressurized vessels known as autoclaves, is useful in electronic circuits for precise filtration, frequency control and timing for consumer and military use. Several ingredients are used in producing cultured quartz, including seed crystals, lascas, a solution of sodium hydroxide or sodium carbonate, lithium salts and deionized water.

  8. Cathodoluminescence of shocked quartz at the Cretaceous-Tertiary boundary

    NASA Technical Reports Server (NTRS)

    Owen, Michael R.; Anders, Mark H.

    1988-01-01

    Empirical studies have documented an association between rock type and the cathodoluminescence color of constituent quartz grains. Quartz from extrusive igneous sources luminesces uniform pale blue. Quartz from intrusive igneous and high-grade metamorphic rocks generally luminesces darker purple-blue, whereas quartz recrystallized under low-grade metamorphic conditions luminesces reddish-brown. Quartz grains in most sandstones luminesce a heterogeneous mixture of these colors because the grains were derived from a variety of ultimate source rocks. If shocked quartz found at the Cretaceous-Tertiary (K-T) boundary is volcanic in origin, its cathodoluminescence should be predominantly pale blue. Alternatively, quartz grains derived from bolide impact upon, and ejection of, mixed igneous, metamorphic, and sedimentary rocks should luminesce a variety of colors. Grain mounts of sand collected at the K-T boundary horizon from the Clear Creek North site in the Raton Basin, Colorado were examined. Shocked quartz luminesced a variety of colors and very few grains luminesced the pale blue color that is typical of volcanic quartz. It was concluded that the shocked quartz was derived from a petrologically diverse source region without substantial volcanic contribution. Most shocked grains apparently were derived from low-grade metamorphic rocks, with a slightly smaller contribution from high-grade metamorphic and intrusive igneous rocks. Rare quartz grains with brown-luminescing rims reflect a minor addition from detrital sedimentary sources. The apparent relative abundances of intrusive (and rare extrusive) igneous, metamorphic, and sedimentary ultimate source rocks suggested by CL colors of shock-deformed quartz at the K-T boundary is consistent with a crustal/supracrustal origin for the grains.

  9. Crystallization and uplift path of late Variscan granites evidenced by quartz chemistry and fluid inclusions: Example from the Land's End granite, SW England

    NASA Astrophysics Data System (ADS)

    Drivenes, Kristian; Larsen, Rune Berg; Müller, Axel; Sørensen, Bjørn Eske

    2016-05-01

    The megacrystic, coarse-grained granite of the Land's End granitic complex, SW England, has been investigated by analyzing fluid inclusions, trace elements, and cathodoluminescence textures of quartz. By applying the TitaniQ geothermobarometer together with the cathodoluminescence textures, a two-stage emplacement process is proposed. K-feldspar and quartz phenocrysts crystallized in a deep magma chamber at ca. 18-20 km depth. The phenocrysts were transported together with the melt to a shallow emplacement depth at ca. 5-9 km in multiple intrusive events, causing the composite appearance of the granitic complex. This model of emplacement concurs with similar granites from the Erzgebirge. At the emplacement level, the magma exsolved an aqueous fluid with average salinity of 17.3% m/m NaCl and 9.7% m/m CaCl2. Fluids with higher salinities were exsolved deeper in the system, as the magma experienced stages of water saturation and water undersaturation during ascent from the deep magma chamber. The complex fluid inclusion textures are the results of multiple stages of entrapment of aqueous fluids in the host phases as multiple recharge events from the deeper magma chamber supplied fresh melts and aqueous volatiles. Titanium contents in quartz are closely related to the panchromatic cathodoluminescence intensity, and the Al/Ti ratio is reflected by the 3.26 eV/2.70 eV ratio of hyperspectral cathodoluminescence.

  10. Paragenesis and chemical characteristics of the celsian-hyalophane-K-feldspar series and associated Ba-Cr micas in barite-bearing strata of the Mesoarchaean Ghattihosahalli Belt, Western Dharwar Craton, South India

    NASA Astrophysics Data System (ADS)

    Raith, Michael M.; Devaraju, Tadasore C.; Spiering, Beate

    2014-04-01

    The upper greenschist - lower amphibolite facies, argillaceous to chemical-exhalative metasedimentary sequence of the Mesoarchaean Ghattihosahalli Schist Belt (GHSB), southern India, has been examined with a special focus on the paragenesis and solid solution characteristics of barian feldspars and associated dioctahedral Ba-Cr-bearing micas. Barian feldspars occur as untwinned porphyroblasts in a recrystallized finely banded matrix of barite, quartz and minor white mica. Idioblastic celsian (Cls98-76Or2-20Ab1-8) and hyalophane (Cls55-39Or35-51Ab10) predate the greenschist-facies foliation, whereas xenoblastic hyalophane (Cls44-35Or45-59Ab8-17) and mantles on celsian (Cls45-35Or42-60Ab13-5) as well as xenoblastic barian K-feldspar (Cls6Or90Ab2) postdate the last fabric-defining event. The preservation of extremely complex zoning patterns down to the micron-scale shows that diffusional homogenization did not operate at fluid-present low to medium-grade conditions (350-550 °C, 3-5 kb). Microstructures indicate that at these conditions barian feldspars deform exclusively by brittle fracturing and do not undergo recrystallization. Barian feldspar compositions confirm the positive correlation of Na-content with temperature and the existence of a narrow asymmetric compositional gap (Cls90-85↔Cls55, ~350 °C) which probably closes at lower amphibolite facies conditions (Xc ~Cls75; Tc ~550 °C). White micas are solid solutions of the end-members muscovite, ganterite (Ba0.5 K0.5)Al2(Al1.5Si2.5)O10(OH)2, paragonite, celadonite with a significant substitution of [VI]Al by Cr. Zoning is a common feature with cores being enriched in Ba. The data document extensive Ba substitution for K from muscovite to ganterite, exclusively controlled by the coupled substitution [XII]K + [IV]Si ↔ [XII]Ba + [IV]Al and strongly dependent on bulk composition. The extent of solid solution from (Ms+Gnt) towards paragonite and celadonite end-members is controlled by the miscibility gap in the

  11. Removal of Retired Alkali Metal Test Systems

    SciTech Connect

    BREHM, W.F.

    2003-01-01

    This paper describes the successful effort to remove alkali metals, alkali metal residues, and piping and structures from retired non-radioactive test systems on the Hanford Site. These test systems were used between 1965 and 1982 to support the Fast Flux Test Facility and the Liquid Metal Fast Breeder Reactor Program. A considerable volume of sodium and sodium-potassium alloy (NaK) was successfully recycled to the commercial sector; structural material and electrical material such as wiring was also recycled. Innovative techniques were used to safely remove NaK and its residues from a test system that could not be gravity-drained. The work was done safely, with no environmental issues or significant schedule delays.

  12. Removal of Retired Alkali Metal Test Systems

    SciTech Connect

    Brehm, W. F.; Church, W. R.; Biglin, J. W.

    2003-02-26

    This paper describes the successful effort to remove alkali metals, alkali metal residues, and piping and structures from retired non-radioactive test systems on the Hanford Site. These test systems were used between 1965 and 1982 to support the Fast Flux Test Facility and the Liquid Metal Fast Breeder Reactor Program. A considerable volume of sodium and sodium-potassium alloy (NaK) was successfully recycled to the commercial sector; structural material and electrical material such as wiring was also recycled. Innovative techniques were used to safely remove NaK and its residues from a test system that could not be gravity-drained. The work was done safely, with no environmental issues or significant schedule delays.

  13. Geopolymers and Related Alkali-Activated Materials

    NASA Astrophysics Data System (ADS)

    Provis, John L.; Bernal, Susan A.

    2014-07-01

    The development of new, sustainable, low-CO2 construction materials is essential if the global construction industry is to reduce the environmental footprint of its activities, which is incurred particularly through the production of Portland cement. One type of non-Portland cement that is attracting particular attention is based on alkali-aluminosilicate chemistry, including the class of binders that have become known as geopolymers. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint and with the potential for performance advantages over traditional cements in certain niche applications. This review discusses the synthesis of alkali-activated binders from blast furnace slag, calcined clay (metakaolin), and fly ash, including analysis of the chemical reaction mechanisms and binder phase assemblages that control the early-age and hardened properties of these materials, in particular initial setting and long-term durability. Perspectives for future research developments are also explored.

  14. Contributed Review: Quartz force sensing probes for micro-applications.

    PubMed

    Abrahamians, Jean-Ochin; Pham Van, Laurent; Régnier, Stéphane

    2016-07-01

    As self-sensing and self-exciting probes, quartz sensors present many advantages over silicon cantilevers for microscopy, micro-robotics, and other micro-applications. Their development and use is further bolstered by the fact that they can be manufactured from common quartz components. This paper therefore reviews applications of the increasingly popular quartz tuning fork probes as force sensors in the literature and examines the options for higher-frequency quartz probes using the other available types of flexional, thickness-shear or length-extensional resonators. PMID:27475541

  15. The Occurrence of Quartz in Coal Fly Ash Particles.

    PubMed

    Meij, R; Nagengast, S; Te Winkel, H

    2000-01-01

    In spite of the presence of quartz, coal fly ash can be considered as a nuisance or inert dust. Respirable crystalline silica (e.g., quartz) is notorious for the induction of, for example, progressive massive fibrosis (PMF); besides, in 1997 the IARC stated that crystalline silica in the form of quartz or cristobalite from occupational sources is carcinogenic to humans. Quartz is present in both coal and residual ash. Ash originates from combustion of pulverised coal and, once removed from the flue gases by electrostatic precipitators (ESPs), it is called pulverized fuel ash (PFA). Thus, occupational exposure to PFA could also include exposure to silica. However, epidemiological studies did not show evidence of progressive massive fibrosis (PMF). In vitro tests demonstrated that PFA is less toxic than silica, and in vivo data of PFA did not support the importance of silica content for toxicity. Commissioned by the Dutch coal-fired power plants, KEMA has started a research project to determine the quartz content in coal and the corresponding PFA. It appears that on average 50% of the a-quartz in coal is found again in the total fraction of PFA (D50(ae) 31 µm, where Dsotae) is the aerodynamically mass median diameter), whereas 16% is found in an even finer fraction (D50(ae) 10 µm). The remaining part of the quartz is embedded in a glass phase. Scanning electron microscopy (SEM) with x-ray microanalyses (XMA) of cross-sections of 11,130 ash particles showed that quartz in PFA is present as unmelted sand particles. These quartz particles are angularly shaped. However, two types are to be distinguished: free coarse angular quartz particles (not respirable) and small angular quartz particles within the PFA particles. From the SEM/XMA results, it has to be concluded that the quartz in the respirable fraction is predominantly present within the original molten PFA particle. Since the effects of quartz are surface related, this elucidates the negative results of quartz

  16. Contributed Review: Quartz force sensing probes for micro-applications

    NASA Astrophysics Data System (ADS)

    Abrahamians, Jean-Ochin; Pham Van, Laurent; Régnier, Stéphane

    2016-07-01

    As self-sensing and self-exciting probes, quartz sensors present many advantages over silicon cantilevers for microscopy, micro-robotics, and other micro-applications. Their development and use is further bolstered by the fact that they can be manufactured from common quartz components. This paper therefore reviews applications of the increasingly popular quartz tuning fork probes as force sensors in the literature and examines the options for higher-frequency quartz probes using the other available types of flexional, thickness-shear or length-extensional resonators.

  17. Partial melting and fractionation in the Mesa Chivato alkali basalt-trachyte series, Mount Taylor Volcanic Field, New Mexico

    NASA Astrophysics Data System (ADS)

    Schrader, C. M.; Schmidt, M. E.; Crumpler, L. S.; Wolff, J. A.

    2012-12-01

    Mesa Chivato comprises a series of alkaline cones, flows, and domes within the Mount Taylor Volcanic Field (MTVF) in northwest New Mexico. Compositions range from alkali basalt to trachyte. Intermediate magmas are less well represented than mafic and felsic rocks, but benmoreites and transitional benmoreite-trachytes provide a window into the differentiation processes. Major element, trace element, and isotopic data suggest that petrogenesis of benmoreite proceeded by fractional crystallization of mafic liquids and magma mixing with partially melted mafic rocks. Major element mass balance models permit the derivation of transitional benmoreite/trachyte from the benmoreite by 20-25% crystallization of microphenocryst phases (olivine, plagioclase, Ti-magnetite, and apatite) and further fractionation to trachyte by 10-15% crystallization of olivine, plagioclase and alkali feldspar, Fe-Ti oxide, and apatite. These models are supported by SiO2-Sr and -Ba systematics. However, the hawaiite to benmoreite gap cannot be crossed by fractional crystallization alone. While major element models permit the mafic lavas to yield the benmoreite, they require extensive fractionation of clinopyroxene and plagioclase - this is unsupported by petrography (clinopyroxene phenocrysts are rare in the mafic rocks and lacking in the intermediate rocks) and cannot explain the benmoreite's very high Sr contents (>1800 ppm), which would have been depleted by plagioclase fractionation. From LA-ICPMS analysis of plagioclase: 87Sr/86Sr of early alkali basalt (0.70285-0.70300) and late hawaiite (0.70406-0.70421) bracket the 87Sr/86Sr of the benmoreite (0.70361-0.70406). Thus, either could represent the fractionated liquid parental to the benmoreite and the other the partially melted source.

  18. Quantum magnetism of alkali Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Malinovskaya, Svetlana; Liu, Gengyuan

    2016-05-01

    We discuss a method to control dynamics in many-body spin states of 87Rb Rydberg atoms. The method permits excitation of cold gases and form ordered structures of alkali atoms. It makes use of a two-photon excitation scheme with circularly polarized and linearly chirped pulses. The method aims for controlled quantum state preparation in large ensembles. It is actual for experiments studding the spin hopping dynamics and realization of quantum random walks.

  19. Alkali Metal Heat Pipe Life Issues

    NASA Technical Reports Server (NTRS)

    Reid, Robert S.

    2004-01-01

    One approach to space fission power system design is predicated on the use of alkali metal heat pipes, either as radiator elements, thermal management components, or as part of the core primary heat-transfer system. This synopsis characterizes long-life core heat pipes. References are included where more detailed information can be found. Specifics shown here are for demonstrational purposes and do not necessarily reflect current Project Prometheus point designs.

  20. Alkali metal protective garment and composite material

    SciTech Connect

    Ballif, J.L.; Yuan, W.W.

    1980-09-16

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium are described. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  1. Alkali metal protective garment and composite material

    SciTech Connect

    Ballif, III, John L.; Yuan, Wei W.

    1980-01-01

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  2. Study of superconducting state parameters of alkali alkali binary alloys by a pseudopotential

    NASA Astrophysics Data System (ADS)

    Vora, Aditya M.

    2006-12-01

    A detailed study of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential μ∗, transition temperature TC, isotope effect exponent α and effective interaction strength N OV of ten alkali-alkali binary alloys i.e. Li 1- xNa x, Li 1- xK x, Li 1- xRb x, Li 1- xCs x, Na 1- xK x, Na 1- xRb x, Na 1- xCs x, K 1- xRb x, K 1- xCs x and Rb 1- xCs x are made within the framework of the model potential formalism and employing the pseudo-alloy-atom (PAA) model for the first time. We use the Ashcroft’s empty core (EMC) model potential for evaluating the superconducting properties of alkali alloys. Five different forms of local field correction functions viz. Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used to incorporate the exchange and correlation effects. A considerable influence of various exchange and correlation functions on λ and μ∗ is found from the present study. Reasonable agreement with the theoretical values of the SSP of pure components is found (corresponding to the concentration x = 0 or 1). It is also concluded that nature of the SSP strongly depends on the value of the atomic volume Ω0 of alkali-alkali binary alloys.

  3. Quantitative modeling of quartz vein sealing

    NASA Astrophysics Data System (ADS)

    Wendler, Frank; Okamoto, Atsushi; Schwarz, Jens-Oliver; Enzmann, Frieder; Blum, Philipp

    2014-05-01

    Mineral precipitation significantly effects many aspects of fluid-rock interaction across all length scales, as the dynamical change of permeability, of mechanical interaction and redistribution of dissolved material. The hydrothermal growth of quartz establishes one of the most important mineralization processes in fractures. Tectonically caused fracturing, deformation and fluid transport leaves clear detectable traces in the microstructure of the mineralized veins. As these patterns give hints on the deformation history and the fluid pathways through former fracture networks, accurate spatio-temporal modeling of vein mineralization is of special interest, and the objective of this study. Due to the intricate polycrystalline geometries involved, the underlying physical processes like diffusion, advection and crystal growth have to be captured at the grain scale. To this end, we adapt a thermodynamically consistent phase-field model (PFM), which combines a kinetic growth law and mass transport equations with irreversible thermodynamics of interfaces and bulk phases. Each grain in the simulation domain is captured by a phase field with individual orientation given by three Euler angles. The model evolves in discrete time steps using a finite difference algorithm on a regular grid, optimized for large grain assemblies. The underlying processes are highly nonlinear, and for geological samples, boundary conditions as well as many of the physical parameters are not precisely known. One motivation in this study is to validate the adequately parameterized model vs. hydrothermal experiments under defined (p,T,c) conditions. Different from former approaches in vein growth simulation, the PFM is configured using thermodynamic data from established geochemical models. Previously conducted batch flow experiments of hydrothermal quartz growth were analyzed with electron backscatter diffraction (EBSD) and used to calibrate the unknown kinetic anisotropy parameters. In the

  4. Transport properties of alkali metal doped fullerides

    SciTech Connect

    Yadav, Daluram Yadav, Nishchhal

    2015-07-31

    We have studied the intercage interactions between the adjacent C{sub 60} cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C{sub 60} phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, T{sub c}, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C{sub 60} phonons as 5 K, which is much lower as compared to reported T{sub c} (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity.

  5. Transport properties of alkali metal doped fullerides

    NASA Astrophysics Data System (ADS)

    Yadav, Daluram; Yadav, Nishchhal

    2015-07-01

    We have studied the intercage interactions between the adjacent C60 cages and expansion of lattice due to the intercalation of alkali atoms based on the spring model to estimate phonon frequencies from the dynamical matrix for the intermolecular alkali-C60 phonons. We considered a two-peak model for the phonon density of states to investigate the nature of electron pairing mechanism for superconducting state in fullerides. Coulomb repulsive parameter and the electron phonon coupling strength are obtained within the random phase approximation. Transition temperature, Tc, is obtained in a situation when the free electrons in lowest molecular orbital are coupled with alkali-C60 phonons as 5 K, which is much lower as compared to reported Tc (20 K). The superconducting pairing is mainly driven by the high frequency intramolecular phonons and their effects enhance it to 22 K. The importance of the present study, the pressure effect and normal state transport properties are calculated within the same model leading superconductivity.

  6. Ion Pairing in Alkali Nitrate Electrolyte Solutions.

    PubMed

    Xie, Wen Jun; Zhang, Zhen; Gao, Yi Qin

    2016-03-10

    In this study, we investigate the thermodynamics of alkali nitrate salt solutions, especially the formation of contact ion pairs between alkali cation and nitrate anion. The ion-pairing propensity shows an order of LiNO3 < NaNO3 < KNO3. Such results explain the salt activity coefficients and suggest that the empirical "law of matching water affinity" is followed by these alkali nitrate salt solutions. The spatial patterns of contact ion pairs are different in the three salt solutions studied here: Li(+) forms the contact ion pair with only one oxygen of the nitrate while Na(+) and K(+) can also be shared by two oxygens of the nitrate. In reproducing the salt activity coefficient using Kirkwood-Buff theory, we find that it is essential to include electronic polarization for Li(+) which has a high charge density. The electronic continuum correction for nonpolarizable force field significantly improves the agreement between the calculated activity coefficients and their experimental values. This approach also improves the performance of the force field on salt solubility. From these two aspects, this study suggests that electronic continuum correction can be a promising approach to force-field development for ions with high charge densities. PMID:26901167

  7. Quartz tuning fork based microwave impedance microscopy

    NASA Astrophysics Data System (ADS)

    Cui, Yong-Tao; Ma, Eric Yue; Shen, Zhi-Xun

    2016-06-01

    Microwave impedance microscopy (MIM), a near-field microwave scanning probe technique, has become a powerful tool to characterize local electrical responses in solid state samples. We present the design of a new type of MIM sensor based on quartz tuning fork and electrochemically etched thin metal wires. Due to a higher aspect ratio tip and integration with tuning fork, such design achieves comparable MIM performance and enables easy self-sensing topography feedback in situations where the conventional optical feedback mechanism is not available, thus is complementary to microfabricated shielded stripline-type probes. The new design also enables stable differential mode MIM detection and multiple-frequency MIM measurements with a single sensor.

  8. Contact freezing induced by biological (Snomax) and mineral dust (K-feldspar) particles

    NASA Astrophysics Data System (ADS)

    Hoffmann, N.; Schäfer, M.; Duft, D.; Kiselev, A. A.; Leisner, T.

    2013-12-01

    The contact freezing of supercooled cloud droplets is one of the potentially important and the least investigated heterogeneous mechanism of ice formation in tropospheric clouds [1]. On the time scales of cloud lifetime the freezing of supercooled water droplets via contact mechanism may occur at higher temperature compared to the same IN immersed in the droplet. In our experiment we study single water droplets freely levitated in an Electrodynamic Balance [2]. We have shown previously that the rate of freezing at given temperature is governed only by the rate of droplet -particle collision and by the properties of the contact ice nuclei [2, 3]. Recently, we have extended our experiments to feldspar, being the most abundant component of the atmospheric mineral dust particles, and Snomax, as a proxy for atmospheric biological Ice Nuclei (IN). In this contribution we show that both IN exhibits the same temperature, size and material dependency observed previously in immersion mode [4, 5]. Based on these results, we limit the number of mechanisms that could be responsible for the enhancement of contact nucleation of ice in supercooled water. [1] - Ladino, L. A., Stetzer, O., and Lohmann, U.: Contact freezing: a review, Atmos. Chem. Phys. Discuss., 13, 7811-7869, doi:10.5194/acpd-13-7811-2013, 2013. [2] - Hoffmann, N., Kiselev, A., Rzesanke, D., Duft, D., and Leisner, T.: Experimental quantification of contact freezing in an electrodynamic balance, Atmos. Meas. Tech. Discuss., 6, 3407-3437, doi:10.5194/amtd-6-3407-2013, 2013. [3] - Hoffmann, N., Duft, D., Kiselev, A., and Leisner, T.: Contact freezing efficiency of mineral dust aerosols studied in an electrodynamic balance: quantitative size and temperature dependence for illite particles, Faraday Discuss., doi: 10.1039/C3FD00033H, 2013. [4] - Atkinson, James D., Murray, Benjamin J., Woodhouse, Matthew T., Whale, Thomas F., Baustian, Kelly J., Carslaw, Kenneth S., Dobbie, Steven, O'Sullivan, Daniel, and Malkin, Tamsin

  9. Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

    PubMed Central

    Ma, Yufei; Yu, Guang; Zhang, Jingbo; Yu, Xin; Sun, Rui; Tittel, Frank K.

    2015-01-01

    A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 μm continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively. PMID:25825977

  10. Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

    NASA Astrophysics Data System (ADS)

    Lammert, Heiko; Heuer, Andreas

    2005-12-01

    The mixed-alkali effect in the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed-alkali slow down longer residence times and an increased probability of correlated backjumps are identified. The slow down is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronger and more retarding for the larger ions, the smaller ions can be temporarily accommodated. Also correlations between unlike as well as like cations are demonstrated that support cooperative behavior.

  11. Method for the safe disposal of alkali metal

    DOEpatents

    Johnson, Terry R.

    1977-01-01

    Alkali metals such as those employed in liquid metal coolant systems can be safely reacted to form hydroxides by first dissolving the alkali metal in relatively inert metals such as lead or bismuth. The alloy thus formed is contacted with a molten salt including the alkali metal hydroxide and possibly the alkali metal carbonate in the presence of oxygen. This oxidizes the alkali metal to an oxide which is soluble within the molten salt. The salt is separated and contacted with steam or steam-CO.sub.2 mixture to convert the alkali metal oxide to the hydroxide. These reactions can be conducted with minimal hydrogen evolution and with the heat of reaction distributed between the several reaction steps.

  12. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film.

    PubMed

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong

    2016-09-01

    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone. PMID:27501513

  13. Passivation of quartz for halogen-containing light sources

    DOEpatents

    Falkenstein, Zoran

    1999-01-01

    Lifetime of halogen containing VUV, UV, visible or IR light sources can be extended by passivating the quartz or glass gas containers with halogens prior to filling the quartz with the halogen and rare gas mixtures used to produce the light.

  14. Determination of the common and rare alkalies in mineral analysis

    USGS Publications Warehouse

    Wells, R.C.; Stevens, R.E.

    1934-01-01

    Methods are described which afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. The procedures are relatively rapid and based chiefly on the use of chloroplatinic acid, absolute alcohol and ether, and ammonium sulfate. The percentages of all the alkalies found in a number of minerals are given.

  15. Environmental mercury contamination around a chlor-alkali plant

    SciTech Connect

    Lodenius, M.; Tulisalo, E.

    1984-04-01

    The chlor-alkali industry is one of the most important emitters of mercury. This metal is effectively spread from chlor-alkali plants into the atmosphere and it has been reported that only a few percent of the mercury emissions are deposited locally the major part spreading over very large areas. The purpose of this investigation was to study the spreading of mercury up to 100 km from a chlor-alkali plant using three different biological indicators.

  16. Accretion and canal impacts in a rapidly subsiding wetland II: Feldspar marker horizon technique

    USGS Publications Warehouse

    Cahoon, D.R.; Turner, R.E.

    1989-01-01

    Recent (6-12 months) marsh sediment accretion and accumulation rates were measured with feldspar marker horizons in the vicinity of natural waterways and man-made canals with spoil banks in the rapidly subsiding environment of coastal Louisiana. Annual accretion rates in a Spartina alterniflora salt marsh in the Mississippi deltaic plain averaged 6 mm in marsh adjacent to canals compared to 10 mm in marsh adjacent to natural waterways. The rates, however, were not statistically significantly different. The average rate of sediment accretion in the same salt marsh region for a transect perpendicular to a canal (13 mm yr-1) was significantly greater than the rate measured for a transect perpendicular to a natural waterway (7 mm yr-1). Measurements of soil bulk density and organic matter content from the two transects were also different. This spatial variability in accretion rates is probably related to (1) spoil bank influences on local hydrology; and (2) a locally high rate of sediment input from lateral erosion associated with pond enlargement. In a brackish Spatina patens marsh on Louisiana's chenier plain, vertical accretion rates were the same along natural and canal waterways (3-4 mm yr-1) in a hydrologically restricted marsh region. However, the accretion rates for both waterways were significantly lower than the rates along a nonhydrologically restricted natural waterway nearby (11 mm yr-1). The vertical accretion of matter displayed semi-annual differences in the brackish marsh environment.

  17. Xenon diffusion following ion implantation into feldspar - Dependence on implantation dose

    NASA Technical Reports Server (NTRS)

    Melcher, C. L.; Burnett, D. S.; Tombrello, T. A.

    1982-01-01

    The diffusion properties of xenon implanted into feldspar, a major mineral in meteorites and lunar samples, are investigated in light of the importance of xenon diffusion in the interpretation of early solar system chronologies and the retention time of solar-wind-implanted Xe. Known doses of Xe ions were implanted at an energy of 200 keV into single-crystal plagioclase targets, and depth profiles were measured by alpha particle backscattering before and after annealing for one hour at 900 or 1000 C. The fraction of Xe retained following annealing is found to be strongly dependent on implantation dose, being greatest at a dose of 3 x 10 to the 15th ions/sq cm and decreasing at higher and lower doses. Xe retention is also observed to be unaffected by two-step anneals, or by implantation with He or Ar. Three models of the dose-dependent diffusion properties are considered, including epitaxial crystal regrowth during annealing controlled by the extent of radiation damage, the creation of trapping sites by radiation damage, and the inhibition of recrystallization by Xe during annealing

  18. Microwave GaAs Integrated Circuits On Quartz Substrates

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.; Mehdi, Imran; Wilson, Barbara

    1994-01-01

    Integrated circuits for use in detecting electromagnetic radiation at millimeter and submillimeter wavelengths constructed by bonding GaAs-based integrated circuits onto quartz-substrate-based stripline circuits. Approach offers combined advantages of high-speed semiconductor active devices made only on epitaxially deposited GaAs substrates with low-dielectric-loss, mechanically rugged quartz substrates. Other potential applications include integration of antenna elements with active devices, using carrier substrates other than quartz to meet particular requirements using lifted-off GaAs layer in membrane configuration with quartz substrate supporting edges only, and using lift-off technique to fabricate ultrathin discrete devices diced separately and inserted into predefined larger circuits. In different device concept, quartz substrate utilized as transparent support for GaAs devices excited from back side by optical radiation.

  19. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

    Hitchcock, D.C.; Mailhe, C.C.; De Jonghe, L.C.

    1985-07-10

    Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

  20. Electrochemical devices utilizing molten alkali metal electrode-reactant

    DOEpatents

    Hitchcock, David C.; Mailhe, Catherine C.; De Jonghe, Lutgard C.

    1986-01-01

    Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

  1. A model that helps explain Sr-isotope disequilibrium between feldspar phenocrysts and melt in large-volume silicic magma systems

    NASA Astrophysics Data System (ADS)

    Duffield, Wendell A.; Ruiz, Joaquin

    1998-12-01

    Feldspar phenocrysts of silicic volcanic rocks are commonly in Sr-isotopic disequilibrium with groundmass. In some cases the feldspar is more radiogenic, and in others it is less radiogenic. Several explanations have been published previously, but none of these is able to accommodate both senses of disequilibrium. We present a model by which either more- or less-radiogenic feldspar (or even both within a single eruptive unit) can originate. The model requires a magma body open to interaction with biotite- and feldspar-bearing wall rock. Magma is incrementally contaminated as wall rock melts incongruently. Biotite preferentially melts first, followed by feldspar. Such melting behavior, which is supported by both field and experimental studies, first contaminates magma with a relatively radiogenic addition, followed by a less-radiogenic addition. Feldspar phenocrysts lag behind melt (groundmass of volcanic rock) in incorporating the influx of contaminant, thus resulting in Sr-isotopic disequilibrium between the crystals and melt. The sense of disequilibrium recorded in a volcanic rock depends on when eruption quenches the contamination process. This model is testable by isotopic fingerprinting of individual feldspar crystals. For a given set of geologic boundary conditions, specific core-to-rim Sr-isotopic profiles are expectable. Moreover, phenocrysts that nucleate at different times during the contamination process should record different and predictable parts of the history. Initial results of Sr-isotopic fingerprinting of sanidine phenocrysts from the Taylor Creek Rhyolite are consistent with the model. More tests of the model are desirable.

  2. Electrodes For Alkali-Metal Thermoelectric Converters

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  3. High power diode pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.

    2008-05-01

    Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

  4. Cathode architectures for alkali metal / oxygen batteries

    SciTech Connect

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  5. Elucidation of transport mechanism and enhanced alkali ion transference numbers in mixed alkali metal-organic ionic molten salts.

    PubMed

    Chen, Fangfang; Forsyth, Maria

    2016-07-28

    Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion transference number at concentrations approaching 50 mol% Li(+) or Na(+), relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali-anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li(+) in a phosphonium ionic liquid, thus an increasing alkali transference number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions. PMID:27375042

  6. (abstract) Fundamental Mechanisms of Electrode Kinetics and Alkali Metal Atom Transport at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kisor, A.; Kikkert, S. K.

    1993-01-01

    The mechanisms of electrode kinetics and mass transport of alkali metal oxidation and alkali metal cation reduction at the solid electrolyte/porous electrode boundary as well as alkali metal transport through porous metal electrodes has important applications in optimizing device performance in alkali metal thermal to electric converter (AMTEC) cells which are high temperature, high current density electrochemical cells. Basic studies of these processes also affords the opportunity to investigate a very basic electrochemical reaction over a wide range of conditions; and a variety of mass transport modes at high temperatures via electrochemical techniques. The temperature range of these investigations covers 700K to 1240K; the alkali metal vapor pressures range from about 10(sup -2) to 10(sup 2) Pa; and electrodes studied have included Mo, W, Mo/Na(sub 2)MoO(sub 4), W/Na(sub 2)WO(sub 4), WPt(sub x), and WRh(sub x) (1.0 < x < 6.0 ) with Na at Na-beta'-alumina, and Mo with K at K-beta'-alumina. Both liquid metal/solid electrolyte/alkali metal vapor and alkali metal vapor/solid electrolyte/vapor cells have been used to characterize the reaction and transport processes. We have previously reported evidence of ionic, free molecular flow, and surface transport of sodium in several types of AMTEC electrodes.

  7. Intracavity quartz-enhanced photoacoustic sensor

    SciTech Connect

    Borri, S. Galli, I.; Mazzotti, D.; Giusfredi, G.; De Natale, P.; Patimisco, P.; Scamarcio, G.; Spagnolo, V.; Akikusa, N.; Yamanishi, M.

    2014-03-03

    We report on a spectroscopic technique named intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) employed for sensitive trace-gas detection in the mid-infrared spectral region. It is based on a combination of QEPAS with a buildup optical cavity. The sensor includes a distributed feedback quantum cascade laser emitting at 4.33 μm. We achieved a laser optical power buildup factor of ∼500, which corresponds to an intracavity laser power of ∼0.75 W. CO{sub 2} has been selected as the target molecule for the I-QEPAS demonstration. We achieved a detection sensitivity of 300 parts per trillion for 4 s integration time, corresponding to a noise equivalent absorption coefficient of 1.4 × 10{sup −8} cm{sup −1} and a normalized noise-equivalent absorption of 3.2 × 10{sup −10} W cm{sup −1} Hz{sup −1/2}.

  8. Recycling of quartz-poor/lithic-rich foreland-basin sediments in arid climate (Euphrates-Tigris-Karun river system)

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Juboury, Ali Ismail Al; Zoleikhaei, Yousef; Vermeesch, Pieter; Hamzah Abdulhussein Jotheri, Jaafar; Akkoca, Dicle Bal; Allen, Mark; Andò, Sergio; Limonta, Mara; Padoan, Marta; Resentini, Alberto; Vezzoli, Giovanni

    2016-04-01

    In this detailed petrological analysis of a large source-to-sink sediment-routing system (catchment area > 1 million km2) we document its several peculiarities, and illustrate a rich petrographic and heavy-mineral dataset integrated by bulk-sediment geochemistry and detrital-zircon U-Pb geochronological data that widens the spectrum of compositions generally assumed as paradigmatic for orogenic settings. We test traditional versus upgraded sedimentary-petrology models in the endeavor to derive a more refined conceptual model of reference, in order to enhance the power of provenance analysis but also to define its limitations and understand which secret of nature is likely to remain beyond reach in our efforts to reconstruct orogenic landscapes of the past. Sands derived from the Zagros-Southeast Anatolian fold-thrust belt contain an abundance of lithic grains derived not only first-cycle from carbonates, cherts, mudrocks, arc volcanics, and obducted mantle serpentinites representing the exposed shallow structural level of the orogen, but also recycled from Neogene molassic strata exposed in the foothills. Quartz, K-feldspar and mica are equally scarce in first-cycle and recycled sediments. This quartz-poor petrographic signature, characterizing the broad undissected tectonic domain of the Anatolia-Iranian plateau, is markedly distinct from that of sands shed by highly elevated and dissected collision orogens of the same mountain system such as the Himalaya or the Alps. Arid climate in the region allows full preservation of chemically unstable grains including carbonate and mafic/ultramafic rock fragments even through more than a single sedimentary cycle. Also, it reduces transport capacity of fluvial systems, which dump most of their load in Mesopotamian marshlands upstream of the Arabian/Persian Gulf allochemical carbonate factory. Quartz-poor orogenic sediments from the Zagros-Southeast Anatolian range mix with quartz-rich recycled sands ultimately derived from

  9. The role of carboxylic acids in albite and quartz dissolution: An experimental study under diagenetic conditions

    NASA Astrophysics Data System (ADS)

    Franklin, Stan P.; Hajash, Andrew, Jr.; Dewers, Thomas A.; Tieh, Thomas T.

    1994-10-01

    Simple water soluble organic acids may promote secondary porosity development in sandstones during diagenesis by increasing feldspar solubility and dissolution rate. To test this hypothesis, Amelia albite and Brazilian hydrothermal quartz were reacted with 0.07 m acetate and 0.07 m acetate-0.005 m oxalate solutions at selected pH values, and distilled water. Pore fluid chemistry was monitored through time at various flow rates to obtain both solubility and dissolution rate data. The experiments were conducted in large volume, semi-static, flow-through systems at 100°C and 347 bars. These systems simulate subsurface flow rates, low mass water/rock, and high surface area/fluid mass. Acetate and acetate + oxalate solutions significantly increase albite solubility at temperatures, pressures, and pH values typical of diagenetic environments. Albite solubilities increased in acetate and acetate + oxalate solutions by factors of 2 and 3.4, respectively, compared to distilled water. In these same solutions, Al concentrations were ≈ 140 and ≈480 times higher than that calculated for kaolinite solubility at the same conditions without organic species. These enhanced solubilities occur at pH values (4.6-4.8) that may overlap with formation waters. In contrast to albite, quartz solubility was essentially identical in all solutions investigated. Dissolution rates in the acid region decreased with increasing pH in the acetate and acetate + oxalate solutions. Slopes of log rate vs. pH curves were ≈0.6 for acetate and ≈0.3 for acetate + oxalate. Although the effects of acetate on the dissolution rate are small, the effects of oxalate are significant. A rate law valid for albite dissolution at 100°C, oxalate concentrations to 0.01 m, and pH values ranging from 3.4 to 5.5 is given below (assuming activity coefficients = 1 and acetate rate ≈ the proton-promoted rate): Rtotal = 5.88 × 10 -11+ 5.01 × 10 -8m 0.56H+ + 6.7 ×10 -102.3 × 10 -4m O x/(1.0+2.3 × 10 -4 m O x

  10. Correlation of basic TL, OSL and IRSL properties of ten K-feldspar samples of various origins

    NASA Astrophysics Data System (ADS)

    Sfampa, I. K.; Polymeris, G. S.; Pagonis, V.; Theodosoglou, E.; Tsirliganis, N. C.; Kitis, G.

    2015-09-01

    Feldspars stand among the most widely used minerals in dosimetric methods of dating using thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Having very good dosimetric properties, they can in principle contribute to the dating of every site of archaeological and geological interest. The present work studies basic properties of ten naturally occurring K-feldspar samples belonging to three feldspar species, namely sanidine, orthoclase and microcline. The basic properties studied are (a) the influence of blue light and infrared stimulation on the thermoluminescence glow-curves, (b) the growth of OSL, IRSL, residual TL and TL-loss as a function of OSL and IRSL bleaching time and (c) the correlation between the OSL and IRSL signals and the energy levels responsible for the TL glow-curve. All experimental data were fitted using analytical expressions derived from a recently developed tunneling recombination model. The results show that the analytical expressions provide excellent fits to all experimental results, thus verifying the tunneling recombination mechanism in these materials and providing valuable information about the concentrations of luminescence centers.

  11. Highly retentive core domains in K-feldspar preserve argon ages from high temperature stages of granite exhumation

    NASA Astrophysics Data System (ADS)

    Forster, Marnie; Lister, Gordon

    2016-04-01

    Retentive core domains are characterized by diffusion parameters that imply K-feldspar should be able to retain argon even at temperatures near or above the granite solidus. In this case it should be possible to date granite emplacement using argon geochronology, and the same answer should be obtained as by using other methods. We present one case study where this is the case, from the elevated Capoas granite stock on Palawan, in the Philippines, and another where it is not, from the South Cyclades Shear Zone, on Ios, Greece. We attempt to determine the factors such as the role of fluid ingress in triggering the in situ recrystallization that can eliminate and/or modify the core domains, leading to relatively youthful ages. Thermochronology is still possible, because less retentive diffusion domains exist, but different methods need to be applied to interpret the data. The work also demonstrates that K-feldspar can be sufficiently retentive as to allow direct dating of processes that reduce the dimensions of diffusion domains, e.g., cataclased and/or recrystallized K-feldspar in fault rock and/or mylonite. These are important developments in the methodology of 40Ar/39Ar geochronology, but to further advance we need to clarify the nature of these highly retentive core domains. In particular, we need better understand how they are modified by microstructural processes during deformation and metamorphism. We need also to assess the role of any crystal structural changes during step-heating in vacuo.

  12. Towards a magmatic quartz database: tracing melt sources

    NASA Astrophysics Data System (ADS)

    Tailby, N. D.; Ackerson, M. R.; Watson, E. B.; Thomas, J. B.

    2014-12-01

    Quartz composition has seen increasing interest among the scientific community over the last decade due to new calibrations (e.g., Ti-in-quartz) and the proliferation of trace element analytical facilities. What is presently lacking in the field of quartz research is a quartz composition database. Such a single body of information can be used to evaluate whether variation seen in different crystallization environments is equally manifest in quartz composition. In this study we present >2000 new quartz analyses from >70 different granitoids and volcanic settings from around the globe (Lachlan Fold Belt, High Himalaya, French Massif, Cordilleran, Caledonian, White Mountains, Bishop, Toba, Snake River, Oman ophiolite and a number of other select locations). This dataset also combines data from a number of previous studies and together the data may collectively be used to determine which geochemical characteristics can be used to distinguish quartz from different magma types. A number of trace element concentrations or ratios (e.g., Al/Ti, Ge, Li, P and B) are notably useful when distinguishing peraluminous (e.g., cordierite-bearing granitoid) systems from more metaluminous systems (e.g., hornblende granodiorite) or plagiogranites.

  13. Climate dependence of feldspar weathering in shale soils along a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Dere, Ashlee L.; White, Timothy S.; April, Richard H.; Reynolds, Brian; Miller, Thomas E.; Knapp, Elizabeth P.; McKay, Larry D.; Brantley, Susan L.

    2013-12-01

    Although regolith, the mantle of physically, chemically, and biologically altered material overlying bedrock, covers much of Earth’s continents, the rates and mechanisms of regolith formation are not well quantified. Without this knowledge, predictions of the availability of soil to sustain Earth’s growing population are problematic. To quantify the influence of climate on regolith formation, a transect of study sites has been established on the same lithology - Silurian shale - along a climatic gradient in the northern hemisphere as part of the Susquehanna Shale Hills Critical Zone Observatory, Pennsylvania, USA. The climate gradient is bounded by a cold/wet end member in Wales and a warm/wet end member in Puerto Rico; in between, mean annual temperature (MAT) and mean annual precipitation (MAP) increase to the south through New York, Pennsylvania, Virginia, Tennessee and Alabama. The site in Puerto Rico does not lie on the same shale formation as the Appalachian sites but is similar in composition. Soils and rocks were sampled at geomorphologically similar ridgetop sites to compare and model shale weathering along the transect. Focusing on the low-concentration, non-nutrient element Na, we observe that the extent and depth of Na depletion is greater where mean annual temperature (MAT) and precipitation (MAP) are higher. Na depletion, a proxy for feldspar weathering, is the deepest reaction documented in the augerable soil profiles. This may therefore be the reaction that initiates the transformation of high bulk-density bedrock to regolith of low bulk density. Based on the shale chemistry along the transect, the time-integrated Na release rate (QNa) increases exponentially as a function of MAT and linearly with MAP. NY, the only site with shale-till parent material, is characterized by a QNa that is 18 times faster than PA, an observation which is attributed to the increased surface area of minerals due to grinding of the glacier and kinetically limited

  14. Relationship between amorphous silica and precious metal in quartz veins

    NASA Astrophysics Data System (ADS)

    Harrichhausen, N.; Rowe, C. D.; Board, W. S.; Greig, C. J.

    2015-12-01

    Super-saturation of silica is common in fault fluids, due to pressure changes associated with fracture, fault slip, or temperature gradients in hydrothermal systems. These mechanisms lead to precipitation of amorphous silica, which will recrystallize to quartz under typical geologic conditions. These conditions may also promote the saturation of precious metals, such as gold, and the precipitation of nanoparticles. Previous experiments show that charged nanoparticles of gold can attach to the surface of amorphous silica nanoparticles. Thus, gold and silica may be transported as a colloid influencing mineralization textures during amorphous silica recrystallization to quartz. This may enrich quartz vein hosted gold deposits, but the instability of hydrous silica during subsequent deformation means that the microstructural record of precipitation of gold is lost. We investigate a recent, shallow auriferous hydrothermal system at Dixie Valley, Nevada to reveal the nano- to micro-scale relationships between gold and silica in fresh veins. Fault slip surfaces at Dixie Valley exhibit layers of amorphous silica with partial recrystallization to quartz. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) show amorphous silica can contain a few wt. % gold while areas recrystallized to quartz are barren. At the Jurassic Brucejack deposit in British Columbia, Canada we observe the cryptocrystalline quartz textures that may indicate recrystallization from amorphous silica within quartz-carbonate veins containing high grade gold. Comb quartz within syntaxial veins, vugs, and coating breccia clasts indicate structural dilation. Vein geometry is investigated to determine relative importance of fault slip in creating dilational sites. By comparing quartz-carbonate veins from the Dixie Valley to Brucejack, we can determine whether amorphous silica formed in different environments show similar potential to affect precious metal mineralization.

  15. Plastic Deformation of O+ Oriented Quartz Single Crystals

    NASA Astrophysics Data System (ADS)

    Poston, E. J.; Holyoke, C. W., III; Kronenberg, A. K.

    2015-12-01

    The strength of wet quartz deforming by dislocation creep significantly influences the strength of mid to lower crust. Dislocation creep of quartz in Earth's crust is dominated by slip on the basal slip system. However, very little is known about the temperature, strain rate, or water fugacity dependence of this slip system. In order to better understand the rheology of the basal slip system, we deformed single crystals of synthetic quartz, with the basal slip system oriented at 45° to the compression direction (O+ orientation). Each core was annealed at 900°C and 1 atm for 24 hours to convert the gel-type water defects found in synthetic quartz into fluid inclusions, like those observed in milky quartz. FTIR analysis indicate that water contents (200-450 H/106Si) were not affected by the annealing process. The annealed single crystals were then deformed in a Griggs piston-cylinder rock deformation apparatus using a solid salt assembly, at temperatures from 800 to 900°C, strain rates from 10-6 to 10-4/s, and a confining pressure of 1.5 GPa. The strength of the quartz crystals increases with faster strain rates and decreases with increasing temperature. During some of the faster strain rate steps at 800°C, the crystals did not deform plastically before the differential stress reached the confining pressure, whereas they deformed at low stresses at 800°C and 10-6/s. The microstructures visible in the deformed samples are consistent with dislocation creep. The samples exhibit undulatory extinction, and show no deformation lamellae or subgrain formation. The strength of synthetic quartz crystals with low water contents deformed in this study is greater than milky quartz single crystals with high water contents deformed at the same conditions in other studies. These results indicate that the strength of basal slip system in quartz is affected by both water content and water fugacity.

  16. Mechanisms of classical crystal growth theory explain quartz and silicate dissolution behavior

    PubMed Central

    Dove, Patricia M.; Han, Nizhou; De Yoreo, James J.

    2005-01-01

    The central control of mineral weathering rates on biogeochemical systems has motivated studies of dissolution for more than 50 years. A complete physical picture that explains widely observed variations in dissolution behavior is lacking, and some data show apparent serious inconsistencies that cannot be explained by the largely empirical kinetic “laws.” Here, we show that mineral dissolution can, in fact, be understood through the same mechanistic theory of nucleation developed for mineral growth. In principle, this theory should describe dissolution but has never been tested. By generalizing nucleation rate equations to include dissolution, we arrive at a model that predicts how quartz dissolution processes change with undersaturation from step retreat, to defect-driven and homogeneous etch pit formation. This finding reveals that the “salt effect,” recognized almost 100 years ago, arises from a crossover in dominant nucleation mechanism to greatly increase step density. The theory also explains the dissolution kinetics of major weathering aluminosilicates, kaolinite and K-feldspar. In doing so, it provides a sensible origin of discrepancies reported for the dependence of kaolinite dissolution and growth rates on saturation state by invoking a temperature-activated transition in the nucleation process. Although dissolution by nucleation processes was previously unknown for oxides or silicates, our mechanism-based findings are consistent with recent observations of dissolution (i.e., demineralization) in biological minerals. Nucleation theory may be the missing link to unifying mineral growth and dissolution into a mechanistic and quantitative framework across the continuum of driving force. PMID:16230632

  17. Superconductivity in alkali metal intercalated iron selenides.

    PubMed

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  18. Durability of Alkali Activated Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Ellis, K.; Alharbi, N.; Matheu, P. S.; Varela, B.; Hailstone, R.

    2015-11-01

    The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. The scientific literature provides many examples of alkali activated slag with high compressive strengths; however research into the durability and resistance to aggressive environments is still necessary for applications in harsh weather conditions. In this study two design mixes of blast furnace slag with mine tailings were activated with a potassium based solution. The design mixes were characterized by scanning electron microscopy, BET analysis and compressive strength testing. Freeze-thaw testing up to 100 freeze-thaw cycles was performed in 10% road salt solution. Our findings included compressive strength of up to 100 MPa after 28 days of curing and 120 MPa after freeze-thaw testing. The relationship between pore size, compressive strength, and compressive strength after freeze-thaw was explored.

  19. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  20. Unconventional Superconductivity of Alkali-doped Fullerenes

    NASA Astrophysics Data System (ADS)

    Potocnik, Anton; Krajnc, Andraz; Jeglic, Peter; Prassides, Kosmas; Rosseinsky, Matthew J.; Arcon, Denis

    2014-03-01

    The superconductivity of the alkali-doped fullerenes (A3C60, A = alkali metal) has been so far discussed within the standard theory of superconductivity developed by Bardeen, Cooper and Shrieffer (BCS), even thought, they exhibit relatively high critical temperatures (up to Tc = 32 K). However, after our recent high-pressure measurements on Cs3C60 such description became questionable. We have shown that the superconducting phase of A3C60, in fact, borders the antiferromagnetic insulating phase (AFI), commonly observed for high-temperature superconductors like cuprates or pnictides. In addition, we also increased the maximal Tc to 38 K. To investigate this peculiar superconductivity close to the border with AFI state we employed nuclear magnetic resonance technique on Cs3-xRbxC60 and on Cs3C60 at various high pressures. Our results could not be correctly explained either by the standard BCS or the extended BCS that includes electron-electron repulsion interaction - the Migdal-Eliashberg theory. Far better agreement is obtained by the Dynamical Mean Field Theory. Due to similarity with other unconventional superconductors these results could also be relevant to other unconventional high-temperature superconductors.

  1. Decalcification resistance of alkali-activated slag.

    PubMed

    Komljenović, Miroslav M; Baščarević, Zvezdana; Marjanović, Nataša; Nikolić, Violeta

    2012-09-30

    This paper analyses the effects of decalcification in concentrated 6M NH(4)NO(3) solution on mechanical and microstructural properties of alkali-activated slag (AAS). Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Decalcification process led to a decrease in strength, both in AAS and in CEM II, and this effect was more pronounced in CEM II. The decrease in strength was explicitly related to the decrease in Ca/Si atomic ratio of C-S-H gel. A very low ratio of Ca/Si ~0.3 in AAS was the consequence of coexistence of C-S-H(I) gel and silica gel. During decalcification of AAS almost complete leaching of sodium and tetrahedral aluminum from C-S-H(I) gel also took place. AAS showed significantly higher resistance to decalcification in relation to the benchmark CEM II due to the absence of portlandite, high level of polymerization of silicate chains, low level of aluminum for silicon substitution in the structure of C-S-H(I), and the formation of protective layer of polymerized silica gel during decalcification process. In stabilization/solidification processes alkali-activated slag represents a more promising solution than Portland-slag cement due to significantly higher resistance to decalcification. PMID:22818592

  2. Dynamics of reactive ultracold alkali polar molecules

    NASA Astrophysics Data System (ADS)

    Quéméner, Goulven; Bohn, John; Petrov, Alexander; Kotochigova, Svetlana

    2011-05-01

    Recently, ultracold polar molecules of KRb have been created. These molecules are chemically reactive and their lifetime in a trap is limited. However, their lifetime increases when they are loaded into a 1D optical lattice in the presence of an electric field. These results naturally raise the question of manipulating ultracold collisions of other species of alkali dimer molecules, with an eye toward both novel stereochemistry, as well as suppressing unwanted reactions, to enable condensed matter applications. In this talk, we report on a comparative study between the bi-alkali polar molecules of LiNa, LiK, LiRb, LiCs which have been predicted to be reactive. We compute the isotropic C6 coefficients of these systems and we predict the elastic and reactive rate coefficients when an electric field is applied in a 1D optical lattice. We will discuss the efficacy of evaporative cooling for each species. This work was supported by a MURI-AFOSR grant.

  3. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical..., chemical destruction and carbon adsorption. (iv) Release to water. Requirements as specified in § 721.90...

  4. Formation of lysinoalanine in egg white under alkali treatment.

    PubMed

    Zhao, Yan; Luo, Xuying; Li, Jianke; Xu, Mingsheng; Tu, Yonggang

    2016-03-01

    To investigate the formation mechanism of lysinoalanine (LAL) in eggs during the alkali treatment process, NaOH was used for the direct alkali treatment of egg white, ovalbumin, and amino acids; in addition, the amount of LAL formed during the alkali treatment process was measured. The results showed that the alkali treatment resulted in the formation of LAL in the egg white. The LAL content increased with increasing pH and temperature, with the LAL content first increasing and then leveling off with increasing time. The amount of LAL formed in the ovalbumin under the alkali treatment condition accounted for approximately 50.51% to 58.68% of the amount of LAL formed in the egg white. Thus, the LAL formed in the ovalbumin was the main source for the LAL in the egg white during the alkali treatment process. Under the alkali treatment condition, free L-serine, L-cysteine, and L-cystine reacted with L-lysine to form LAL; therefore, they are the precursor amino acids of LAL formed in eggs during the alkali treatment process. PMID:26772660

  5. Recovery of alkali metal constituents from catalytic coal conversion residues

    DOEpatents

    Soung, Wen Y.

    1984-01-01

    In a coal gasification operation (32) or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by contacting them (46, 53, 61, 69) with water or an aqueous solution to remove water-soluble alkali metal constituents and produce an aqueous solution enriched in said constituents. The aqueous solution thus produced is then contacted with carbon dioxide (63) to precipitate silicon constituents, the pH of the resultant solution is increased (81), preferably to a value in the range between about 12.5 and about 15.0, and the solution of increased pH is evaporated (84) to increase the alkali metal concentration. The concentrated aqueous solution is then recycled to the conversion process (86, 18, 17) where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.

  6. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  7. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  8. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  9. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... defined in 40 CFR 721.3) containing amines. (b) ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject...

  10. Self-discharge in bimetallic cells containing alkali metal

    NASA Technical Reports Server (NTRS)

    Foster, M. S.; Hesson, J. C.; Shimotake, H.

    1969-01-01

    Theoretical analysis of thermally regenerative bimetallic cells with alkali metal anodes shows a relation between the current drawn and the rate of discharge under open-circuit conditions. The self-discharge rate of the cell is due to the dissolution and ionization of alkali metal atoms in the fused-salt electrolyte

  11. COMPLEX FLUORIDES OF PLUTONIUM AND AN ALKALI METAL

    DOEpatents

    Seaborg, G.T.

    1960-08-01

    A method is given for precipitating alkali metal plutonium fluorides. such as KPuF/sub 5/, KPu/sub 2/F/sub 9/, NaPuF/sub 5/, and RbPuF/sub 5/, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal- fluoride.

  12. 40 CFR 721.4740 - Alkali metal nitrites.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in...

  13. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl...

  14. Feldspar dissolution kinetics and Gibbs free energy dependence in a CO 2-enriched groundwater system, Green River, Utah

    NASA Astrophysics Data System (ADS)

    Kampman, Niko; Bickle, Mike; Becker, John; Assayag, Nelly; Chapman, Hazel

    2009-07-01

    Reactions between CO 2-charged brines and reservoir minerals might either enhance the long-term storage of CO 2 in geological reservoirs or facilitate leakage by corroding cap rocks and fault seals. Modelling the progress of such reactions is frustrated by uncertainties in the absolute mineral surface reaction rates and the significance of other rate limiting steps in natural systems. Here we use the chemical evolution of groundwater from the Jurassic Navajo Sandstone, part of a leaking natural accumulation of CO 2 at Green River, Utah, in the Colorado Plateau, USA, to place constraints on the rates and potential controlling mechanisms of the mineral-fluid reactions, under elevated CO 2 pressures, in a natural system. The progress of individual reactions, inferred from changes in groundwater chemistry is modelled using mass balance techniques. The mineral reactions are close to stoichiometric with plagioclase and K-feldspar dissolution largely balanced by precipitation of clay minerals and carbonate. Mineral modes, in conjunction with published surface area measurements and flow rates estimated from hydraulic head measurements, are then used to quantify the kinetics of feldspar dissolution. Maximum estimated dissolution rates for plagioclase and K-feldspar are 2 × 10 - 14 and 4 × 10 - 16 mol m - 2 s - 1 , respectively. Fluid ion-activity products are close to equilibrium (e.g. Δ Gr for plagioclase between - 2 and - 10 kJ/mol) and lie in the region in which mineral surface reaction rates show a strong dependence on Δ Gr. Local variation in Δ Gr is attributed to the injection and disassociation of CO 2 which initially depresses silicate mineral saturation in the fluid, promoting feldspar dissolution. With progressive flow through the aquifer feldspar hydrolysis reactions consume H + and liberate solutes to solution which increase mineral saturation in the fluid and rates slow as a consequence. The measured plagioclase dissolution rates at low Δ Gr of 2 × 10

  15. Effects of alkali treatments on Ag nanowire transparent conductive films

    NASA Astrophysics Data System (ADS)

    Kim, Sunho; Kang, Jun-gu; Eom, Tae-yil; Moon, Bongjin; Lee, Hoo-Jeong

    2016-06-01

    In this study, we employ various alkali materials (alkali metals with different base strengths, and ammonia gas and solution) to improve the conductivity of silver nanowire (Ag NW)-networked films. The alkali treatment appears to remove the surface oxide and improve the conductivity. When applied with TiO2 nanoparticles, the treatment appears more effective as the alkalis gather around wire junctions and help them weld to each other via heat emitted from the reduction reaction. The ammonia solution treatment is found to be quick and aggressive, damaging the wires severely in the case of excessive treatment. On the other hand, the ammonia gas treatment seems much less aggressive and does not damage the wires even after a long exposure. The results of this study highlight the effectiveness of the alkali treatment in improving of the conductivity of Ag NW-networked transparent conductive films.

  16. Performance of Straight Steel Fibres Reinforced Alkali Activated Concrete

    NASA Astrophysics Data System (ADS)

    Faris, Meor Ahmad; Bakri Abdullah, Mohd Mustafa Al; Nizar Ismail, Khairul; Muniandy, Ratnasamy; Putra Jaya, Ramadhansyah

    2016-06-01

    This paper focus on the performance of alkali activated concrete produced by using fly ash activated by sodium silicate and sodium hydroxide solutions. These alkali activated concrete were reinforced with straight steel fibres with different weight percentage starting from 0 % up to 5 %. Chemical composition of raw material in the production alkali activated concrete which is fly ash was first identified by using X-ray fluorescence. Results reveal there have an effect of straight steel fibres inclusion to the alkali activated concrete. Highest compressive strength of alkali activated concrete which is 67.72 MPa was obtained when 3 % of straight fibres were added. As well as flexural strength, highest flexural strength which is 6.78 MPa was obtained at 3 % of straight steel fibres inclusions.

  17. Diversity and Mechanisms of Alkali Tolerance in Lactobacilli▿

    PubMed Central

    Sawatari, Yuki; Yokota, Atsushi

    2007-01-01

    We determined the maximum pH that allows growth (pHmax) for 34 strains of lactobacilli. High alkali tolerance was exhibited by strains of Lactobacillus casei, L. paracasei subsp. tolerans, L. paracasei subsp. paracasei, L. curvatus, L. pentosus, and L. plantarum that originated from plant material, with pHmax values between 8.5 and 8.9. Among these, L. casei NRIC 1917 and L. paracasei subsp. tolerans NRIC 1940 showed the highest pHmax, at 8.9. Digestive tract isolates of L. gasseri, L. johnsonii, L. reuteri, L. salivarius subsp. salicinius, and L. salivarius subsp. salivarius exhibited moderate alkali tolerance, with pHmax values between 8.1 and 8.5. Dairy isolates of L. delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, and L. helveticus exhibited no alkali tolerance, with pHmax values between 6.7 and 7.1. Measurement of the internal pH of representative strains revealed the formation of transmembrane proton gradients (ΔpH) in a reversed direction (i.e., acidic interior) at alkaline external-pH ranges, regardless of their degrees of alkali tolerance. Thus, the reversed ΔpH did not determine alkali tolerance diversity. However, the ΔpH contributed to alkali tolerance, as the pHmax values of several strains decreased with the addition of nigericin, which dissipates ΔpH. Although neutral external-pH values resulted in the highest glycolysis activity in the presence of nigericin regardless of alkali tolerance, substantial glucose utilization was still detected in the alkali-tolerant strains, even in a pH range of between 8.0 and 8.5, at which the remaining strains lost most activity. Therefore, the alkali tolerance of glycolysis reactions contributes greatly to the determination of alkali tolerance diversity. PMID:17449704

  18. EPR study of Fe3+ in α-quartz: Further lithium-compensated centers

    NASA Astrophysics Data System (ADS)

    Choi, Deok; Weil, John A.

    1990-12-01

    Fe3+ (S=52) centers in synthetic α-quartz, designated by S'1 and S''1 by previous workers, which are very similar to the previously studied center [FeO4/Li]0α (called S1), have been examined at temperatures around 35 K via an X-band electron-paramagnetic-resonance study. Hyperfine signals due to the Li7 nucleus were detected for both centers, establishing their alkali-metal-ion content. The spin-Hamiltonian parameters were determined, allowing for anisotropy of the g factor as well as [g,D,A(Li7), P(Li7)]-matrix noncoaxiality, and including high-spin terms of the form S4. Evaluation of the results indicates that the lithium 1+ ion is present interstitially near to the substitutional Fe3+ ion (located at a Si4+ site) on the same crystal twofold axis, for all three centers: S1, S'1 and S''1. The designations [FeO4/Li]0α' are proposed for the centers S'1 and S''1, respectively. The relative concentrations of these centers appear to depend sensitively on the growth regions within each crystal.

  19. Quartz crystals detect gas contaminants during vacuum chamber evacuation

    NASA Technical Reports Server (NTRS)

    Stephens, J. B.

    1967-01-01

    Piezoelectric quartz crystals detect condensable gas contaminants backstreaming into a vacuum chamber when a pump is evacuating the chamber. One crystal acts as a thermometer, the other detects mass change. They are energized by electronic equipment which records frequency changes.

  20. Degradation of Glycine and Alanine on Irradiated Quartz

    NASA Astrophysics Data System (ADS)

    Pawlikowski, Maciej; Benko, Aleksandra; Wróbel, Tomasz P.

    2013-04-01

    Recent researches suggest participation of minerals in the formation of life under primordial conditions. Among all of the minerals, quartz seems to be one of the most probable to take part in such processes. However, an external source of energy is needed, e.g. electric discharge. A device simulating the proposed conditions was designed and was used to simulate prebiotic conditions. Investigation of processes occurring during the stimulation of quartz with electric discharge was studied by means of Ultraviolet-visible (UV-VIS) spectroscopy, in order to monitor the generation kinetics of free radicals. Additionally, infrared spectroscopy was applied to identify chemical reaction products created in a solution of alanine or glycine, in the presence of quartz treated with electric discharge. Formation of increased amounts of free radicals, compared to experiments performed without quartz and/or amino acid, is reported, along with identification of possible degradation products of alanine. No synthetic reactions were observed.

  1. A study of optically contacted quartz at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    Optical contacting as a method of joining the quartz components of the instruments for the Gravity Probe-B experiment is evaluated. The strength of the bond between optically contacted fused quartz surfaces at liquid helium temperature was investigated. A test apparatus which can be used for making measurements of the tensile strength of these bonds was designed. Results of the tensile pull tests are given and the reliability of such bonds analyzed.

  2. Solvent-averaged potentials for alkali-, earth alkali-, and alkylammonium halide aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hess, Berk; van der Vegt, Nico F. A.

    2007-12-01

    We derive effective, solvent-free ion-ion potentials for alkali-, earth alkali-, and alkylammonium halide aqueous solutions. The implicit solvent potentials are parametrized to reproduce experimental osmotic coefficients. The modeling approach minimizes the amount of input required from atomistic (force field) models, which usually predict large variations in the effective ion-ion potentials at short distances. For the smaller ion species, the reported potentials are composed of a Coulomb and a Weeks-Chandler-Andersen term. For larger ions, we find that an additional, attractive potential is required at the contact minimum, which is related to solvent degrees of freedom that are usually not accounted for in standard electrostatics models. The reported potentials provide a simple and accurate force field for use in molecular dynamics and Monte Carlo simulations of (poly-)electrolyte systems.

  3. Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

    NASA Technical Reports Server (NTRS)

    Roth, R. S.; Parker, H. S.; Brower, W. S.; Minor, D.

    1974-01-01

    A search was made for new cationic conducting phases in alkali-tantalate and niobate systems. The phase equilibrium diagrams were constructed for the six binary systems Nb2O5-LiNbO3, Nb2O5-NaNbO3, Nb2O5-KNbO3, Ta2O5-NaTaO3, Ta2O5-LiTaO3, and Ta2O5-KTaO3. Various other binary and ternary systems were also examined. Pellets of nineteen phases were evaluated (by the sponsoring agency) by dielectric loss measurements. Attempts were made to grow large crystals of eight different phases. The system Ta2O5-KTaO3 contains at least three phases which showed peaks in dielectric loss vs. temperature. All three contain structures related to the tungsten bronzes with alkali ions in non-stoichiometric crystallographic positions.

  4. Effect of quartz inclusions on plastic flow in marble

    NASA Astrophysics Data System (ADS)

    Dresen, Georg; Evans, Brian; Olgaard, David L.

    To investigate the effect of variations in volume fraction of a second phase on the strength and microstructure of rocks, we produced synthetic marbles with a grainsize of 5-25 µm, containing quartz of similar size, with volume fractions of 0, 5.1, and 20.4 vol.%, and between 3 to 9% porosity. These rocks were deformed in triaxial compression at a strain-rate of 3 × 10-5 s-1 confining pressure of 200 MPa, and 600°C. Marbles containing 20.4 vol.% quartz were almost 5 times stronger than those containing no quartz. The work-hardening rate at given strain increased with quartz content. Marbles containing 20.4 vol.% quartz work-hardened up to 10% strain whereas in single-phase samples work hardening was negligible beyond 3% strain. The dislocation density in the calcite increased with increasing quartz content. The data are consistent with models for the strength of ceramic matrix composites, or with the hypothesis that strength is increased by decreasing porosity.

  5. Optical detectors based on thermoelastic effect in crystalline quartz

    NASA Astrophysics Data System (ADS)

    Chelibanov, V. P.; Ishanin, G. G.

    2015-06-01

    Optical detectors developed on base of thermo elastic effect In quartz crystalline (PTEK) attributed to the thermal detectors group. Such detectors occurred very effective for the registration of pulsed light energy or power of harmonically modulated laser radiation flux in a wide spectral (from UV to far IR) and dynamic ranges (from 10-6 to 300 W / cm2 with cooling) with a time constant up to10-6 seconds. When exposed to electromagnetic radiation occurs at the receiver thermal field which causes mechanical stress in the transient crystalline quartz, which in turn leads to a change in the polarization of crystalline quartz and, as a consequence, to an electric potential difference at the electrodes (the front surface with a conductive coating and damper). The capacitive characteristic of the detector, based on a thermo elastic effect in crystalline quartz, eliminates the possibility of working with constant flow of radiation, which also affects at the frequency response of the detector, since the potential difference appearance in the piezoelectric plate depends on the direction of the forces relative to the axes X, Y, Z of the crystal. Therefore, a certain choice of orientation of the receiving element is necessary in accordance with the physical properties of crystalline quartz. In this paper, a calculation of the sensitivity and frequency characteristics of optical detectors based on the thermo elastic effect in crystalline quartz at the harmonic effects of electromagnetic radiation flux are reported.

  6. Thermal diffusivity of pyroxene, feldspar, and silica melts, glasses, and single-crystals at high temperature

    NASA Astrophysics Data System (ADS)

    Pertermann, M.; Branlund, J.; Whittington, A.; Hofmeister, A.

    2007-12-01

    Thermal diffusivity (D) due to phonon transport (the lattice component) was measured using laser-flash analysis from oriented single-crystals and of glasses above the glass transition, which proxy as melts. Compositions include SiO2, CaMgSi2O6, LiAlSi2O6, NaAlSi3O8, and CaAl2Si2O8. KAlSi3O8 was studied previously. Viscosity measurements of the supercooled liquids, in the range 106.8 to 1012.3 Pas, confirm near-Arrhenian behavior. For all compositions and for crystal and glass, D decreases with T, approaching a constant generally near 1000 K: Dsat, which is larger in the crystal than in the glass. A rapid decrease in D as T is increased further (ca 1400 K for orthoclase) is consistent with crossing the glass transition, verified from our viscosity data on these systems. The amount of the decrease depends on the chemical composition and similar to the relative decrease observed in heat capacity. Orthoclase values for Dsat are 0.65± 0.3 mm2/s for bulk crystal and 0.53+/-0.03 mm2/s for the glass. Constant D = 0.475+/-.01 mm2/s represents melt. Thermal conductivity (klat) of orthoclase glass, calculated using previous results for heat capacity (CP) and our density data, increases with T due to CP strongly increasing with T, reaching a plateau near 1.45 W/m-K for melt, but is always below klat of the crystal. Similar results were obtained from the other systems studied. Melting of silica, pyroxene, and feldspars impedes heat transport, providing positive thermal feedback that may promote further melting in the continental crust. The consistency of the behavior for these different compositions and structures suggests that our results are universal, holding for oceanic lithosphere as well. Melts, due to being disordered, are poor transporters of heat via vibrations. However, d(ln klat)/dP depends inversely on bulk modulus, suggesting that at some high pressure, the thermal conductivity of the melt and corresponding crystal become equal so that retention of heat by melts

  7. Resolving the gap between laboratory and field rates of feldspar weathering

    NASA Astrophysics Data System (ADS)

    Gruber, Chen; Zhu, Chen; Georg, R. Bastian; Zakon, Yevgeny; Ganor, Jiwchar

    2014-12-01

    Weathering rates of silicate minerals observed in the laboratory are in general up to five orders of magnitude higher than those inferred from field studies. The differences between experimental conditions in the laboratory and natural conditions in the field have been thoroughly discussed in previous studies, however, the discrepancy was never fully resolved. It has been shown in past work that if the field conditions are fully simulated in standard laboratory experiments, it is not possible to measure the slow rates of mineral dissolution that are observed in the field using standard laboratory experiments. Therefore, a novel method that uses the change of Si isotopes ratio in spiked solutions is used in the present study to measure weathering rates of feldspar under close-to-natural conditions. A single-point batch experiment (SPBE) of albite dissolution was performed in the present study with an “untreated” albite sample. During the SPBE the dissolution rate was affected by the change of deviation from equilibrium and by the change in the mineral surface reactivity. In order to quantify the effect of the change in surface reactivity on the measured dissolution rates, two multi-point batch experiments (MPBE) were conducted. In those experiments, surface reactivity was found to depend on the amount of dissolved mineral. The decrease in surface reactivity as a function of the amount of dissolved mineral may be described using empirical power laws. Another MPBE was used to measure far-from-equilibrium dissolution rate of albite using a sample that lost most of the highly reactive sites and highly reactive fine crystal during the initial stage of the experiment. Therefore, the change of its surface reactivity is small over the duration of the laboratory experiment (henceforth, “treated” albite sample). Another SPBE was conducted to quantify the effect of deviation from equilibrium on albite dissolution rate under close-to-equilibrium using the

  8. Grain boundary diffusion of oxygen, potassium and calcium in natural and hot-pressed feldspar aggregates

    NASA Astrophysics Data System (ADS)

    Farver, John R.; Yund, Richard A.

    1995-01-01

    Grain boundary diffusion rates of oxygen, potassium and calcium in fine-grained feldspar aggregates were determined experimentally. The starting materials were a natural albite rock from the Tanco pegmatite and aggregates hot-pressed from fragments of Amelia albite or Ab, Or and An composition glasses. The technique employed isotopic tracers (18O, 41K, 42Ca) either evaporated onto the surface or in an aqueous solution surrounding the sample, and depth profiling using an ion microprobe (SIMS). From the depth profiles, the product of the grain boundary diffusion coefficient (D') and effective boundary width (δ) was calculated using numerical solutions to the appropriate diffusion equation. The experimental reproducibility of D'δ is a factor of 3. A separate determination of D' independent of δ yields an effective grain boundary width of ˜3 nm, consistent with high resolution TEM observations of a physical grain boundary width <5 nm. Oxygen (as molecular water) grain boundary diffusion rates were determined in the Ab and Or aggregates at 450°-800°C and 100 MPa (hydrothermal), potassium rates in Or aggregates at 450°-700°C both at 0.1 MPa (in air) and at 100 MPa (hydrothermal), and calcium rates in An aggregates at 700°-1100°C and 0.1 MPa (in air). Oxygen grain boundary diffusion rates are similar in all three of the Ab aggregates and in the Or aggregate. Potassium and oxygen depth profiles measured in the same samples yield different D'δ values, confirming a diffusional transport mechanism. Potassium diffusion in the Or aggregate has a greater activation energy (216 vs 78 kJ/mol) than oxygen, and the Arrhenius relations cross at ˜625°C. Potassium D'δ values in Or aggregates are about a factor of five greater in hydrothermal experiments at 100 MPa than in experiments at 0.1 MPa in air. Calcium grain boundary diffusion rates in An aggregates are 4 to 5 orders of magnitude slower than potassium in Or and have a greater (291 kJ/mol) activation energy. This

  9. Melt rock components in KREEPy breccia 15205: Petrography and mineral chemistry of KREEP basalts and quartz-normative mare basalts

    NASA Technical Reports Server (NTRS)

    Shervais, John W.; Vetter, Scott K.

    1993-01-01

    Many current models for the origin of lunar highland rocks feature as an essential component the assimilation of KREEPy material by primitive magmas parental to the Mg-rich suite and alkali suite plutonic rocks. Similar models have also been proposed for the origin of various mare basalt suites. However, any model which considers assimilation of KREEP an important petrologic process must sooner-or-later deal with the question: what is KREEP? Because pristine KREEP basalts are rare, and most known samples are small (e.g., 15382/15386), the geochemical variability of KREEP basalts is poorly known. Other KREEP compositions which are commonly used in these models include the hypothetical 'high-K KREEP' component of Warren and Wasson, which is derived from Apollo 14 soil data, and the 'superKREEP' quartz-monzodiorite 15405. Lunar breccia 15205 is a polymict regolith breccia that consists of approximately 20% KREEP basalt clasts and 20% quartz-normative basalt clasts in a KREEP-rich matrix. Bulk rock mixing calculations show that this sample comprises about 84% KREEP. The clasts range up to 1 cm in size, but most are considerably smaller. The primary aim is to characterize pristine KREEP basalts petrographically, to establish the range in chemical compositions of KREEP basalts, and to test models that were proposed for their origin. In addition, we may be able to extend the compositional range recognized in the quartz-normative basalt suite and cast some light on its origin as well. Preliminary whole rock geochemical data on the KREEP basalts are presented in a companion paper by M.M. Lindstrom and co-workers. Concentration is on petrography and mineral chemistry of these clasts, and the implications these data have for the origin of the different melt rock suites.

  10. Volcanic Origin of Alkali Halides on Io

    NASA Technical Reports Server (NTRS)

    Schaefer, L.; Fegley, B., Jr.

    2003-01-01

    The recent observation of NaCl (gas) on Io confirms our earlier prediction that NaCl is produced volcanically. Here we extend our calculations by modeling thermochemical equilibrium of O, S, Li, Na, K, Rb, Cs, F, Cl, Br, and I as a function of temperature and pressure in a Pele-like volcanic gas with O/S/Na/Cl/K = 1.518/1/0.05/0.04/0.005 and CI chondritic ratios of the other (as yet unobserved) alkalis and halogens. For reference, the nominal temperature and pressure for Pele is 1760 plus or minus 210 K and 0.01 bars based on Galileo data and modeling.

  11. Heat pipes containing alkali metal working fluid

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1981-01-01

    A technique for improving high temperature evaporation-condensation heat-transfer devices which have important and unique advantage in terrestrial and space energy processing is described. The device is in the form of a heat pipe comprising a sealed container or envelope which contains a capillary wick. The temperature of one end of the heat pipe is raised by the input of heat from an external heat source which is extremely hot and corrosive. A working fluid of a corrosive alkali metal, such as lithium, sodium, or potassium transfers this heat to a heat receiver remote from the heat source. The container and wick are fabricated from a superalloy containing a small percentage of a corrosion inhibiting or gettering element. Lanthanum, scandium, yttrium, thorium, and hafnium are utilized as the alloying metal.

  12. Comparative alkali washing of simulated radioactive sludge

    SciTech Connect

    Fugate, G.A.; Ensor, D.D.; Egan, B.Z.

    1996-10-01

    The treatment of large volumes of radioactive sludge generated from uranium and plutonium recovery processes is a pressing problem in the environmental restoration currently planned at various U.S. Department of Energy sites. This sludge, commonly stored in underground tanks, is mainly in the form of metal oxides or precipitated metal hydroxides and the bulk of this material is nonradioactive. One method being developed to pretreat this waste takes advantage of the amphoteric character of aluminum and other nonradioactive elements. Previous studies have reported on the dissolution of eleven elements from simulated sludge using NaOH solutions up to 6M. This work provides a comparative study using KOH. The effectiveness of the alkali washing as a treatment method to reduce the bulk of radioactive sludge requiring long term isolation will be discussed.

  13. Solid state cell with alkali metal halo-alkali thiocyanate electrolyte

    SciTech Connect

    Rao, B. M.; Silbernagel, B. G.

    1980-02-26

    A novel electrochemical cell is disclosed utilizing: (A) an anode which contains an alkali metal as an anode-active material; (B) a cathode and (C) an electrolyte comprising an electrolytically effective amount of one or more compounds having the formula: (Ax)ma'scn wherein a is an alkali metal, X is a halogen, a' is an alkali metal and 0.1 < or = N < or = 10. Preferred systems include lithium-containing anodes, lithium-containing electrolytes and cathodes which contain cathode-active material selected from the group consisting of cathode-active sulfurs, halogens, halides, chromates, phosphates, oxides and chalcogenides, especially those chalcogenides of the empirical formula mzm wherein M is one or more metals selected from the group consisting of iron, titanium, zirconium, hafnium, niobium, tantalum and vanadium, Z is one or more chalcogens selected from the group consisting of oxygen, sulfur, selenium and tellurium, and M is a numerical value between about 1.8 and about 3.2.

  14. Ionic alkali halide XUV laser feasibility study

    SciTech Connect

    Yang, T.T.; Gylys, V.T.; Bower, R.D.; Harris, D.G.; Blauer, J.A.; Turner, C.E.; Hindy, R.N.

    1989-11-10

    The objective of this work is to assess the feasibility of a select set of ionic alkali halide XUV laser concepts by obtaining the relevant kinetic and spectroscopic parameters required for a proof-of-principle and conceptual design. The proposed lasers operate in the 80--200 nm spectral region and do not require input from outside radiation sources for their operation. Frequency up-conversion and frequency mixing techniques and therefore not considered in the work to be described. An experimental and theoretical study of a new type of laser operating in the extreme ultraviolet wavelength region has been conducted. The lasing species are singly ionized alkali halide molecules such as Rb{sup 2+}F{sub {minus}}, Rb{sup 2+}Br{sup {minus}} and Cs{sup 2+}F{sup {minus}}. These species are similar in electronic structure to the rare gas halide excimers, such as XeF and Krf, except that the ionic molecules emit at wavelengths of 80--200 nm, much shorter than the conventional rare-gas halide excimer laser. The radiative lifetime of these molecules are typically near 1 ns, which is about an order of magnitude shorter than that for rare-gas halide systems. The values of the cross section for stimulated emission are on the order of 1 {times} 10{sup {minus}16}cm{sup 2}. Because of the fundamental similarity to existing UV lasers, these systems show promise as a high power, efficient XUV lasers. 55 refs., 50 figs., 5 tabs.

  15. Composition of steam in the system NaCl-KCl-H2O-quartz at 600°C

    USGS Publications Warehouse

    Fournier, Robert O.; Thompson, J. Michael

    1993-01-01

    In the system NaCl-KCl-H2O, with and without ??-quartz present, steam was equilibrated in a large-volume reaction vessel with brine and/or precipitated salt at 600??C and pressures ranging from about 100 to 0.4 MPa. Episodically, steam was extracted for chemical analysis, accompanied by a decrease in pressure within the reaction vessel. In the absence of precipitated salt, within the analytical uncertainty stoichiometric quantities of Cl and total alkali, metals (Na + K) dissolve in steam coexisting with chloriderich brine. In contrast, in the presence of precipitated salt (in our experiments halite with some KCl in solid solution), significant excess chloride as associated hydrogen chloride (HCl0??) dissolves in steam. The HCl0 is generated by the reaction of steam with solid NaCl(s), producing solid NaOH(s) that diffuses into halite, forming a solid solution. In our quasistatic experiments, compared to dynamic flow-through experiments of others, higher initial ratios of H2O/NaCl have apparently resulted in higher model fractions of NaOH(s) in solid solution in halite. This, in turn, resulted in incrementally higher concentrations of associated NaOHo dissolved in steam. Addition of quartz to the system NaCl + KC1 + H2O resulted in an order of magnitude increase in the concentration of HCl0 dissolved in steam, apparently as a consequence of the formation of sodium disilicate by reaction of silica with NaOH(s). The measured dissolved silica in steam saturated with alkali halides at 600??C in the pressure range 7-70 MPa agrees nicely with calculated values of the solubility of ??-quartz obtained using the equation of Fournier and Potter (1982), corrected for dissolved salt by the method of fournier (1983). Na K ratios in steam at 600??C tend to be slightly greater than in coexisting brine. When precipitated halite is present, larger mole fractions of NaOH(s) in solid solution in that halite apparently result in even larger Na K ratios in coexisting steam

  16. Controlled in-situ dissolution of an alkali metal

    DOEpatents

    Jones, Jeffrey Donald; Dooley, Kirk John; Tolman, David Donald

    2012-09-11

    A method for the controllable dissolution of one or more alkali metals from a vessel containing a one or more alkali metals and/or one or more partially passivated alkali metals. The vessel preferably comprising a sodium, NaK or other alkali metal-cooled nuclear reactor that has been used. The alkali metal, preferably sodium, potassium or a combination thereof, in the vessel is exposed to a treatment liquid, preferably an acidic liquid, more preferably citric acid. Preferably, the treatment liquid is maintained in continuous motion relative to any surface of unreacted alkali metal with which the treatment liquid is in contact. The treatment liquid is preferably pumped into the vessel containing the one or more alkali metals and the resulting fluid is extracted and optionally further processed. Preferably, the resulting off-gases are processed by an off-gas treatment system and the resulting liquids are processed by a liquid disposal system. In one preferred embodiment, an inert gas is pumped into the vessel along with the treatment liquid.

  17. Ultrasonic coal washing to leach alkali elements from coals.

    PubMed

    Balakrishnan, S; Reddy, V Midhun; Nagarajan, R

    2015-11-01

    Deposition of fly ash particles onto heat-transfer surfaces is often one of the reasons for unscheduled shut-downs of coal-fired boilers. Fouling deposits encountered in convective sections of a boiler are characterized by arrival of ash particles in solidified (solid) state. Fouling is most frequently caused by condensation and chemical reaction of alkali vapors with the deposited ash particles creating a wet surface conducive to collect impacting ash particles. Hence, the amount of alkali elements present in coals, which, in turn, is available in the flue gas as condensable vapors, determines the formation and growth of fouling deposits. In this context, removal of alkali elements becomes vital when inferior coals having high-ash content are utilized for power generation. With the concept of reducing alkali elements present in a coal entering the combustor, whereby the fouling deposits can either be minimized or be weakened due to absence of alkali gluing effect, the ultrasonic leaching of alkali elements from coals is investigated in this study. Ultrasonic water-washing and chemical-washing, in comparison with agitation, are studied in order to estimate the intensification of the alkali removal process by sonication. PMID:26186840

  18. Alkali elemental and potassium isotopic compositions of Semarkona chondrules

    USGS Publications Warehouse

    Alexander, C.M. O'D.; Grossman, J.N.

    2005-01-01

    We report measurements of K isotope ratios in 28 Semarkona chondrules with a wide range of petrologic types and bulk compositions as well as the compositions of CPX-mesostasis pairs in 17 type I Semarkona chondrules, including two chondrules with radial alkali zonation and 19 type II chondrules. Despite the wide range in K/Al ratios, no systematic variations in K isotopic compositions were found. Semarkona chondrules do not record a simple history of Rayleigh-type loss of K. Experimentally determined evaporation rates suggest that considerable alkali evaporation would have occurred during chondrule formation. Nevertheless, based on Na CPX-mesostasis distribution coefficients, the alkali contents of the cores of most chondrules in Semarkona were probably established at the time of final crystallization. However, Na CPX-mesostasis distribution coefficients also show that alkali zonation in type I Semarkona chondrules was produced by entry of alkalis after solidification, probably during parent body alteration. This alkali metasomatism may have gone to completion in some chondrules. Our preferred explanation for the lack of systematic isotopic enrichments, even in alkali depleted type I chondrule cores, is that they exchanged with the ambient gas as they cooled. ?? The Meteoritical Society, 2005.

  19. Similar quartz crystallographic textures in rocks of continental earth's crust (by neutron diffraction data): I. Quartz textures in monomineral rocks

    NASA Astrophysics Data System (ADS)

    Nikitin, A. N.; Ivankina, T. I.; Ullemeyer, K.; Vasin, R. N.

    2008-09-01

    Quartz crystallographic textures in different rocks have been investigated by neutron diffraction. Various types of crystallographic textures of quartz-bearing mineral associations in monomineral and multiphase rocks from a representative collection of samples have been revealed and classified. Experimental investigations have been performed on special neutron texture diffractometers designed at the Frank Laboratory of Neutron Physics and mounted in the seventh channel of the IBR-2 reactor at the Joint Institute for Nuclear Research (Dubna).

  20. Similar quartz crystallographic textures in rocks of continental earth's crust (by neutron diffraction data): I. Quartz textures in monomineral rocks

    SciTech Connect

    Nikitin, A. N. Ivankina, T. I.; Ullemeyer, K.; Vasin, R. N.

    2008-09-15

    Quartz crystallographic textures in different rocks have been investigated by neutron diffraction. Various types of crystallographic textures of quartz-bearing mineral associations in monomineral and multiphase rocks from a representative collection of samples have been revealed and classified. Experimental investigations have been performed on special neutron texture diffractometers designed at the Frank Laboratory of Neutron Physics and mounted in the seventh channel of the IBR-2 reactor at the Joint Institute for Nuclear Research (Dubna).

  1. The Nature of Feldspar Clouding and Its Paleomagnetic Significance With Reference To The 2.45 Ga Matachewan Dyke Swarm, Canada

    NASA Astrophysics Data System (ADS)

    Halls, Henry C.; Zhang, Baoxing; Garland, Mary

    Clouding in calcic plagioclase is a common occurrence in Precambrian diabase dyke swarms worldwide, particularly those of Paleoproterozoic age. The occurrence of this clouding in 2.45 Ga Matachewan dykes within uplifted blocks of the Kapuskasing Zone (KZ) in Canada, and not in dykes of the same swarm at shallower crustal levels in surrounding terranes, suggests that the clouding is produced as a re- equilibration of the felspar in response to declining temperatures but in the presence of pressures appropriate to mid - to lower- crustal levels. We have made the following observations on feldspar separates extracted from the dykes: (1) Curie Balance, and low temperature SIRM acquisition studies show Curie temperarures of 580° C and a Verwey transition at 110-120K appropriate for Ti-poor magnetite; (2) Saturation magnetization is proportional to clouding intensity as determined from image analysis techniques; (3) Hysteresis and SEM studies indicate that the particles are small, typically about 1 micron (PSD) in size; (4) A baked contact test on cloudy feldspar dykes within the KZ is negative, but positive for dykes outside the KZ; (5) Magnetite in cloudy feldspars carries a high coercivity N component of magnetization which increases with clouding intensity, whereas dykes outside the KZ mostly carry an older R remanence; (6) Since sets of R dykes become N along strike on entering the KZ, the magnetization carried by cloudy feldspars is secondary; (7) The presence of R host rocks adjacent to an N cloudy dyke and the occasional survival of lower Hc and lower Tub R components in N cloudy dykes within the KZ suggests that the N magnetization of the feldspar magnetite is a CRM; (8) SEM shows that feldspars of different clouding intensity (from image analysis) have a near constant atomic percentage of Fe, so that the degree of clouding is determined in part by the concentration of magnetite rather than by total Fe and indicates that from 30-90% of the total Fe is used in

  2. Suitability of alkaline leaching and etching experiments in the quantification of ASR potential of quartz-rich rocks

    NASA Astrophysics Data System (ADS)

    Kuchařová, Aneta; Šachlová, Šárka; Pertold, Zdeněk; Přikryl, Richard

    2015-04-01

    Three groups of methods are conventionally applied in the assessment of the susceptibility of aggregates used in concrete to be affected by alkali-silica reaction (ASR). The most frequently employed expansion tests (accelerated mortar bar test and concrete prism test, e.g. ASTM C1260, RILEM AAR2, RILEM AAR4.1) quantify ASR potential of aggregates according to the expansion values of mortar bars (resp. concrete prisms) measured after certain testing time period. Petrographic methods are based on the quantification of alkali-reactive phases by polarizing microscopy (e.g. RILEM AAR1). Chemical methods quantify ASR potential according to the amount of Si4+ dissolved into alkaline solution combined with the reduction of alkalinity of the solution (e.g. ASTM C289). The current study focused on the comparison of three approaches: the alkaline etching of polished rock sections and standard chemical method (following ASTM C289) with the measuring of expansion values of mortar bars (following ASTM C1260). Various types of quartz and amorphous SiO2 used for the experiments were separated from rock samples of orthoquartzite, quartz meta-greywacke, pegmatite, phyllite, chert, and flint. Polished rock sections (resp. crushed fraction 0.125/0.250) were used and subjected to leaching in 1M NaOH solution at 80°C for 14 days (resp. 24 hours). After alkaline etching in alkaline solution, the rock sections were analyzed by scanning electron microscopy combined with energy dispersive spectrometer. Representative areas were documented in back scattered electron images and quantified using fully-automatic petrographic image analysis. ASR potential of the polished rock sections was evaluated by the vol. % of area affected by alkaline etching. ASR potential of crushed aggregate was estimated by measurements of Si4+ dissolved into the solution versus the reduction of alkalinity of the solution (following ASTM C289). Classification according to the ASTM C289 indicated three of investigated

  3. Increasing Class C fly ash reduces alkali silica reactivity

    SciTech Connect

    Hicks, J.K.

    2007-07-01

    Contrary to earlier studies, it has been found that incremental additions of Class C fly ash do reduce alkali silica reactivity (ASR), in highly reactive, high alkali concrete mixes. AST can be further reduced by substituting 5% metakaolin or silica fume for the aggregate in concrete mixes with high (more than 30%) Class C fly ash substitution. The paper reports results of studies using Class C fly ash from the Labadie Station plant in Missouri which typically has between 1.3 and 1.45% available alkalis by ASTM C311. 7 figs.

  4. Electrochemical cell utilizing molten alkali metal electrode-reactant

    DOEpatents

    Virkar, Anil V.; Miller, Gerald R.

    1983-11-04

    An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

  5. Synkinematic quartz cementation in partially open fractures in sandstones

    NASA Astrophysics Data System (ADS)

    Ukar, Estibalitz; Laubach, Stephen E.; Fall, Andras; Eichhubl, Peter

    2014-05-01

    Faults and networks of naturally open fractures can provide open conduits for fluid flow, and may play a significant role in hydrocarbon recovery, hydrogeology, and CO2 sequestration. However, sandstone fracture systems are commonly infilled, at least to some degree, by quartz cement, which can stiffen and occlude fractures. Such cement deposits can systematically reduce the overall permeability enhancement due to open fractures (by reducing open fracture length) and result in permeability anisotropies. Thus, it is important to identify the factors that control the precipitation of quartz in fractures in order to identify potential fluid conduits under the present-day stress field. In many sandstones, quartz nucleates syntaxially on quartz grain or cement substrate of the fracture wall, and extends between fracture walls only locally, forming pillars or bridges. Scanning electron microscope cathodoluminescence (SEM-CL) images reveal that the core of these bridges are made up of bands of broken and resealed cement containing wall-parallel fluid inclusion planes. The fluid inclusion-rich core is usually surrounded by a layer of inclusion-poor clear quartz that comprises the lateral cement. Such crack-seal textures indicate that this phase was precipitating while the fractures were actively opening (synkinematic growth). Rapid quartz accumulation is generally believed to require temperatures of 80°C or more. Fluid inclusion thermometry and Raman spectroscopy of two-phase aqueous fluid-inclusions trapped in crack-seal bands may be used to track the P-T-X evolution of pore fluids during fracture opening and crack-seal cementation of quartz. Quartz cement bridges across opening mode fractures in the Cretaceous Travis Peak Formation of the tectonically quiescent East Texas Basin indicate individual fractures opened over a 48 m.y. time span at rates of 16-23 µm/m.y. Similarly, the Upper Cretaceous Mesaverde Group in the Piceance Basin, Colorado contains fractures that

  6. A model that helps explain Sr-isotope disequilibrium between feldspar phenocrysts and melt in large-volume silicic magma systems

    USGS Publications Warehouse

    Duffield, W.A.; Ruiz, J.

    1998-01-01

    Feldspar phenocrysts of silicic volcanic rocks are commonly in Sr-isotopic disequilibrium with groundmass. In some cases the feldspar is more radiogenic, and in others it is less radiogenic. Several explanations have been published previously, but none of these is able to accommodate both senses of disequilibrium. We present a model by which either more- or less-radiogenic feldspar (or even both within a single eruptive unit) can originate. The model requires a magma body open to interaction with biotite- and feldspar-bearing wall rock. Magma is incrementally contaminated as wall rock melts incongruently. Biotite preferentially melts first, followed by feldspar. Such melting behavior, which is supported by both field and experimental studies, first contaminates magma with a relatively radiogenic addition, followed by a less-radiogenic addition. Feldspar phenocrysts lag behind melt (groundmass of volcanic rock) in incorporating the influx of contaminant, thus resulting in Sr-isotopic disequilibrium between the crystals and melt. The sense of disequilibrium recorded in a volcanic rock depends on when eruption quenches the contamination process. This model is testable by isotopic fingerprinting of individual feldspar crystals. For a given set of geologic boundary conditions, specific core-to-rim Sr-isotopic profiles are expectable. Moreover, phenocrysts that nucleate at different times during the contamination process should record different and predictable parts of the history. Initial results of Sr-isotopic fingerprinting of sanidine phenocrysts from the Taylor Creek Rhyolite are consistent with the model. More tests of the model are desirable.Feldspar phenocrysts of silicic volcanic rocks are commonly in Sr-isotopic disequilibrium with groundmass. In some cases the feldspar is more radiogenic, and in others it is less radiogenic. Several explanations have been published previously, but none of these is able to accommodate both senses of disequilibrium. We present a

  7. Electron microprobe study of lunar and planetary zoned plagioclase feldspars: An analytical and experimental study of zoning in plagioclase

    NASA Technical Reports Server (NTRS)

    Smith, R. K.; Lofgren, G. E.

    1982-01-01

    Natural and experimentally grown zoned plagioclase feldspars were examined by electron microprobe. The analyses revealed discontinuous, sector, and oscillary chemical zoning superimposed on continuous normal or reverse zoning trends. Postulated mechanisms for the origin of zoning are based on either physical changes external to the magma (P, T, H2O saturation) or kinetic changes internal to the magma (diffusion, supersaturation, growth rate). Comparison of microprobe data on natural zoned plagioclase with zoned plagioclase grown in controlled experiments show that it may be possible to distinguish zonal development resulting from physio-chemical changes to the bulk magma from local kinetic control on the growth of individual crystals.

  8. Soil chemistry in lithologically diverse datasets: the quartz dilution effect

    USGS Publications Warehouse

    Bern, Carleton R.

    2009-01-01

    National- and continental-scale soil geochemical datasets are likely to move our understanding of broad soil geochemistry patterns forward significantly. Patterns of chemistry and mineralogy delineated from these datasets are strongly influenced by the composition of the soil parent material, which itself is largely a function of lithology and particle size sorting. Such controls present a challenge by obscuring subtler patterns arising from subsequent pedogenic processes. Here the effect of quartz concentration is examined in moist-climate soils from a pilot dataset of the North American Soil Geochemical Landscapes Project. Due to variable and high quartz contents (6.2–81.7 wt.%), and its residual and inert nature in soil, quartz is demonstrated to influence broad patterns in soil chemistry. A dilution effect is observed whereby concentrations of various elements are significantly and strongly negatively correlated with quartz. Quartz content drives artificial positive correlations between concentrations of some elements and obscures negative correlations between others. Unadjusted soil data show the highly mobile base cations Ca, Mg, and Na to be often strongly positively correlated with intermediately mobile Al or Fe, and generally uncorrelated with the relatively immobile high-field-strength elements (HFS) Ti and Nb. Both patterns are contrary to broad expectations for soils being weathered and leached. After transforming bulk soil chemistry to a quartz-free basis, the base cations are generally uncorrelated with Al and Fe, and negative correlations generally emerge with the HFS elements. Quartz-free element data may be a useful tool for elucidating patterns of weathering or parent-material chemistry in large soil datasets.

  9. Quartz concentration trends in metal and nonmetal mining.

    PubMed

    Watts, Winthrop F; Huynh, Tran B; Ramachandran, Gurumurthy

    2012-01-01

    From 1974 through 2010, the Mine Safety and Health Administration (MSHA) collected nearly 147,000 respirable dust samples with a mass of at least 0.1 mg and a minimum of 1% quartz. These samples represent about 50% of all respirable dust compliance samples collected by MSHA. Analysis of these data shows that pockets of high concentrations and overexposure continue to exist. At underground mines, from 2005 to 2010, occupations with >20% of the samples exceeding the permissible exposure limit (PEL) and geometric mean quartz concentrations exceeding the ACGIH threshold limit value of 25 μg/m(3) included mucking, crusher operator, general laborer/utility, and front-end loader operator. During the same period, stone and rock saw operators and bagger and packers working at surface mines and mills also had >20% of the samples exceeding the PEL and geometric mean quartz concentrations >25 μg/m(3). Regardless of mine type or location, slow but steady improvement in exposure levels is seen in jobs involving crushing operations, which are widespread in the mining industry. Crusher operators are more likely to work in an enclosed area where it is easier to apply dust controls and air conditioning. A downward trend is also observed for vehicle equipment operators who drive load-haul-dumps, front-end loaders, trucks, and similar equipment. Crusher operators and vehicle equipment operators represent occupational categories that are widely sampled by MSHA inspectors. A small but statistically significant reduction in the overall mean respirable quartz dust and quartz concentrations from 1993 to 2010 was observed in most commodity groups. Variability from year to year and between commodities is high. Reduction in respirable quartz dust concentration does not necessarily correspond to a reduction in quartz concentration within the same commodity group. These trends are consistent with those reported in previous studies. PMID:23092305

  10. Treated and untreated rock dust: Quartz content and physical characterization.

    PubMed

    Soo, Jhy-Charm; Lee, Taekhee; Chisholm, William P; Farcas, Daniel; Schwegler-Berry, Diane; Harper, Martin

    2016-11-01

    Rock dusting is used to prevent secondary explosions in coal mines, but inhalation of rock dusts can be hazardous if the crystalline silica (e.g., quartz) content in the respirable fraction is high. The objective of this study is to assess the quartz content and physical characteristics of four selected rock dusts, consisting of limestone or marble in both treated (such as treatment with stearic acid or stearates) and untreated forms. Four selected rock dusts (an untreated and treated limestone and an untreated and treated marble) were aerosolized in an aerosol chamber. Respirable size-selective sampling was conducted along with particle size-segregated sampling using a Micro-Orifice Uniform Deposit Impactor. Fourier Transform Infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analyses were used to determine quartz mass and particle morphology, respectively. Quartz percentage in the respirable dust fraction of untreated and treated forms of the limestone dust was significantly higher than in bulk samples, but since the bulk percentage was low the enrichment factor would not have resulted in any major change to conclusions regarding the contribution of respirable rock dust to the overall airborne quartz concentration. The quartz percentage in the marble dust (untreated and treated) was very low and the respirable fractions showed no enrichment. The spectra from SEM-EDX analysis for all materials were predominantly from calcium carbonate, clay, and gypsum particles. No free quartz particles were observed. The four rock dusts used in this study are representative of those presented for use in rock dusting, but the conclusions may not be applicable to all available materials. PMID:27314444

  11. Coating Characterization with the Quartz Crystal Microbalance

    NASA Astrophysics Data System (ADS)

    Sturdy, Lauren F.

    The quartz crystal microbalance is a sensitive tool that can be used to measure the mass, modulus and phase angle of films of appropriate thicknesses. It is can be applied to systems with very varied properties, from liquid to solid, and under many different conditions. In this thesis its capabilities have been used to study the properties of several different systems of relevance to the coatings, art conservation, and rubber communities, in the process of which new techniques and tools were developed to analyze data and improve QCM data collection and experimental design. Alkyd resins, which have been used in artists' paints since the twentieth century, are the subject of the first studies. Alkyds are oil-modified polyesters. These resins are of interest because of their relatively recent use in art and how little is known of the mechanical properties in the early stages of cure. The QCM was shown to be sensitive to the curing process, changes in temperature, and mass change due to exposure to water. Kinetic studies during the first days of curing showed that the curing process can be divided into three regions. The first is dominated by solvent evaporation. In the second, oxygen absorption dominates and the mechanical properties change rapidly. The final stage extends from when the film is touch dry after about a day to years and is characterized by mass loss and continued increases in the modulus. Studying the curing at different temperatures revealed that the reactions do proceed much more rapidly at higher temperatures and an overall energy of activation was calculated for the curing process. The mechanical properties of alkyd resins containing zinc oxide, a white pigment, were studied with the QCM, nanoindentation and dynamic mechanical analysis. These measurements showed increases in the modulus with the inclusion of zinc oxide, and the QCM data showed that the second region started at earlier times as the pigment concentration was increased. Linseed oil is

  12. PB2+ AND ZN2+ ADSORPTION BY A NATURAL ALUMINUM- AND IRON BEARING SURFACE COATING ON AN AQUIFER SAND

    EPA Science Inventory

    Pb 2+ and Zn 2+ adsorption was studied in batch experiments with material collected from a shallow, unconfined aquifer of glacial outwash sand and gravel in Falmouth, Massachusetts, USA. he aquifer solids contain primarily quartz (951 w/w), with minor amounts of alkali feldspars ...

  13. Acoustic wave flow sensor using quartz thickness shear mode resonator.

    PubMed

    Qin, Lifeng; Zeng, Zijing; Cheng, Hongbin; Wang, Qing-Ming

    2009-09-01

    A quartz thickness shear mode (TSM) bulk acoustic wave resonator was used for in situ and real-time detection of liquid flow rate in this study. A special flow chamber made of 2 parallel acrylic plates was designed for flow measurement. The flow chamber has a rectangular flow channel, 2 flow reservoirs for stabilizing the fluid flow, a sensor mounting port for resonator holding, one inlet port, and one outlet port for pipe connection. A 5-MHz TSM quartz resonator was edge-bonded to the sensor mounting port with one side exposed to the flowing liquid and other side exposed to air. The electrical impedance spectra of the quartz resonator at different volumetric flow rate conditions were measured by an impedance analyzer for the extraction of the resonant frequency through a data-fitting method. The fundamental, 3rd, 5th, 7th, and 9th resonant frequency shifts were found to be around 920, 3572, 5947, 8228, and 10,300 Hz for flow rate variation from 0 to 3000 mL/min, which had a corresponding Reynolds number change from 0 to 822. The resonant frequency shifts of different modes are found to be quadratic with flow rate, which is attributed to the nonlinear effect of quartz resonator due to the effective normal pressure imposing on the resonator sensor by the flowing fluid. The results indicate that quartz TSM resonators can be used for flow sensors with characteristics of simplicity, fast response, and good repeatability. PMID:19811997

  14. Nature of radiation-induced defects in quartz

    NASA Astrophysics Data System (ADS)

    Wang, Bu; Yu, Yingtian; Pignatelli, Isabella; Sant, Gaurav; Bauchy, Mathieu

    2015-07-01

    Although quartz (α-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage has not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si-O connectivity defects, e.g., small Si-O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on E' centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependence on the incident energy, of the amount of each type of the point defects formed, and quantify unambiguously the threshold displacement energies for both O and Si atoms. These results provide a comprehensive basis to assess the nature and extent of radiation damage in quartz.

  15. Nature of radiation-induced defects in quartz

    SciTech Connect

    Wang, Bu; Yu, Yingtian; Bauchy, Mathieu; Pignatelli, Isabella; Sant, Gaurav

    2015-07-14

    Although quartz (α-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage has not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si–O connectivity defects, e.g., small Si–O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on E′ centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependence on the incident energy, of the amount of each type of the point defects formed, and quantify unambiguously the threshold displacement energies for both O and Si atoms. These results provide a comprehensive basis to assess the nature and extent of radiation damage in quartz.

  16. All-in-quartz optics for low focal shifts

    NASA Astrophysics Data System (ADS)

    Blomqvist, Mats; Blomster, Ola; Pålsson, Magnus; Campbell, Stuart; Becker, Frank; Rath, Wolfram

    2011-02-01

    High laser power levels in combination with increasing beam quality bring optics performance into focus, particularly with regard to systems with low focal shifts along the optical axis. In industrial applications, this often influences the overall performance of the process, especially if the focal shift is comparable to or in excess of the Rayleigh length. It is commonly accepted that the focal shifts are of thermal nature where lens material, lens coating, geometry and surface contamination all contribute to the direction and extent of the focal shifts. In this paper we will present a novel design of lens packages where a patented all-in-quartz concept is explored. By mounting quartz lenses in hermetically sealed quartz tubes and applying water cooling on the perimeter of the quartz tubes we will reduce or eliminate a number of contributing factors to focal shift problems. The hermetic sealing, carried out in a clean-room environment, will minimize lens surface contamination. Differences in thermal expansion between lens and housing are eliminated as the lens and housing will be of the same material. Absorption of scattered laser light will be efficient as the energy is removed quickly by cooling water and not absorbed by fixed surroundings. Finally, indirect heating from the housing transmitted by radiation and convection to the lenses is avoided. Values of the normalized System Focal Shift Factors (SFSF) for the all-in-quartz optics will be compared to standard lens assemblies at multi-kW laser power levels.

  17. Electric field-induced softening of alkali silicate glasses

    NASA Astrophysics Data System (ADS)

    McLaren, C.; Heffner, W.; Tessarollo, R.; Raj, R.; Jain, H.

    2015-11-01

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  18. The 4843 Alkali Metal Storage Facility Closure Plan

    SciTech Connect

    Not Available

    1991-06-01

    The 4843 AMSF has been used primarily to provide a centralized building to receive and store dangerous and mixed alkali metal waste, including sodium and lithium, which has been generated at the Fast Flux Test Facility and at various other Hanford Site operations that used alkali metals. Most of the dangerous and mixed alkali metal waste received consists of retired equipment from liquid sodium processes. The unit continues to store material. In general, only solid alkali metal waste that is water reactive is stored at the 4843 AMSF. The 4843 AMSF will be closed in a manner consistent with Ecology guidelines and regulations (WAC 173-303-610). The general closure procedure is detailed as follows.

  19. Hall Determination of Atomic Radii of Alkali Metals

    ERIC Educational Resources Information Center

    Houari, Ahmed

    2008-01-01

    I will propose here an alternative method for determining atomic radii of alkali metals based on the Hall measurements of their free electron densities and the knowledge of their crystal structure. (Contains 2 figures.)

  20. Method for intercalating alkali metal ions into carbon electrodes

    DOEpatents

    Doeff, M.M.; Ma, Y.; Visco, S.J.; DeJonghe, L.

    1995-08-22

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.