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Sample records for zn-rich phyllosilicate zn-layered

  1. Liquid crystalline composites containing phyllosilicates

    DOEpatents

    Chaiko, David J.

    2004-07-13

    The present invention provides phyllosilicate-polymer compositions which are useful as liquid crystalline composites. Phyllosilicate-polymer liquid crystalline compositions of the present invention can contain a high percentage of phyllosilicate while at the same time be transparent. Because of the ordering of the particles liquid crystalline composite, liquid crystalline composites are particularly useful as barriers to gas transport.

  2. Liquid crystalline composites containing phyllosilicates

    DOEpatents

    Chaiko,; David, J [Naperville, IL

    2007-05-08

    The present invention provides barrier films having reduced gas permeability for use in packaging and coating applications. The barrier films comprise an anisotropic liquid crystalline composite layer formed from phyllosilicate-polymer compositions. Phyllosilicate-polymer liquid crystalline compositions of the present invention can contain a high percentage of phyllosilicate while remaining transparent. Because of the ordering of the particles in the liquid crystalline composite, barrier films comprising liquid crystalline composites are particularly useful as barriers to gas transport.

  3. Polymer-phyllosilicate nanocomposites and their preparation

    DOEpatents

    Chaiko, David J.

    2007-01-09

    Polymer-phyllosilicate nanocomposites that exhibit superior properties compared to the polymer alone, and methods-for producing these polymer-phyllosilicate nanocomposites, are provided. Polymeric surfactant compatabilizers are adsorbed onto the surface of hydrophilic or natural phyllosilicates to facilitate the dispersal and exfoliation of the phyllosilicate in a polymer matrix. Utilizing polymeric glycol based surfactants, polymeric dicarboxylic acids, polymeric diammonium surfactants, and polymeric diamine surfactants as compatabilizers facilitates natural phyllosilicate and hydrophilic organoclay dispersal in a polymer matrix to produce nanocomposites.

  4. Composite materials with improved phyllosilicate dispersion

    DOEpatents

    Chaiko, David J.

    2004-09-14

    The present invention provides phyllosilicates edge modified with anionic surfactants, composite materials made from the edge modified phyllosilicates, and methods for making the same. In various embodiments the phyllosilicates are also surface-modified with hydrophilic lipophilic balance (HLB) modifying agents, polymeric hydrotropes, and antioxidants. The invention also provides blends of edge modified phyllosilicates and semicrystalline waxes. The composite materials are made by dispersing the edge modified phyllosilicates with polymers, particularly polyolefins and elastomers.

  5. Polyfunctional dispersants for controlling viscosity of phyllosilicates

    DOEpatents

    Chaiko, David J.

    2006-07-25

    This invention provides phyllosilicates and polyfunctional dispersants which can be manipulated to selectively control the viscosity of phyllosilicate slurries. The polyfunctional dispersants used in the present invention, which include at least three functional groups, increase the dispersion and exfoliation of phyllosilicates in polymers and, when used in conjunction with phyllosilicate slurries, significantly reduce the viscosity of slurries having high concentrations of phyllosilicates. The functional groups of the polyfunctional dispersants are capable of associating with multivalent metal cations and low molecular weight organic polymers, which can be manipulated to substantially increase or decrease the viscosity of the slurry in a concentration dependent manner. The polyfunctional dispersants of the present invention can also impart desirable properties on the phyllosilicate dispersions including corrosion inhibition and enhanced exfoliation of the phyllosilicate platelets.

  6. Distribution of phyllosilicates on Ceres

    NASA Astrophysics Data System (ADS)

    Ammannito, Eleonora; De Sanctis, Maria Cristina; Ciarniello, Mauro; Frigeri, Alessandro; Giacomo Carrozzo, Filippo; Combe, Jean Philippe; Ehlmann, Bethany; Marchi, Simone; McSween, Hap Y.; Raponi, Andrea; Castillo-Rogez, Julie C.; Toplis, Michael J.; Tosi, Federico; Longobardo, Andrea; Palomba, Ernesto; Pieters, Carle M.; Raymond, Carol A.; Schenk, Paul; Zambon, Francesca; Russell, Christopher T.

    2016-04-01

    Studies of the dwarf planet Ceres using ground-based and orbiting telescopes proposed a variety of possible surficial composition including water in clay minerals [1], ammoniated phyllosilicates [2], or a mixture of brucite, Mg2CO3 and iron-rich serpentine [3, 4]. But the lack of spectral data in the 2.5 to 2.9 μm interval has precluded definitive identifications. The Dawn spacecraft has been acquiring spectra of the surface of Ceres since January 2015 [5, 6, 7]. The average thermally corrected reflectance spectrum of Ceres shows that the 2.6-4.2μm region is characterized by a broad asymmetric feature, characteristic of H2O/OH bearing materials, with several distinct narrower absorption bands [8]. This spectrum is compatible with the presence on the surface of a mixture of ammoniated-phyllosilicates, Mg-phyllosilicates, carbonates, and dark materials [8]. A strong 2.7-μm absorption dominates the overall spectral properties, and it has been attributed to OH-stretching vibrations in phyllosilicates [9] while the weaker 3.05 μm absorption has been attributed to the presence of NH4+ in phyllosilicates [10]. The spectral parameters of the absorption features at 2.7 and 3.05 μm have been computed to study their position and intensity. The computed spectral position of both absorption features is remarkably homogeneous. The average values are 2.727±0.005 and 3.061±0.005 μm respectively. Since the position of both features is sensitive to the chemical composition of the phyllosilicates, we conclude that the composition of phyllosilicates does not significantly change across the mapped portion of Ceres' surface. The computed values are indicative of Mg-OH phases, like antigorite (Mg-serpentine) or saponite (Mg-smectite) [9]. The presence of Mg-, rather than Fe-serpentine on Ceres may be interpreted as an indication that alteration had been extensive, while the lack of geochemical variation indicates that this is true throughout the exposed upper layer with no

  7. Spectral effects of dehydration on phyllosilicates

    NASA Technical Reports Server (NTRS)

    Bruckenthal, E. A.; Singer, R. B.

    1987-01-01

    Six phyllosilicates were progressively dehydrated under controlled conditions in an effort to study the spectral effects of their dehydration. The spectra obtained at each level of hydration provide information that may be used in future spectroscopic observations of the planets, as well as a data set which compliments the existing body of terrestrial soil knowledge.

  8. Phyllosilicate and Hydrated Sulfate Deposits in Meridiani

    NASA Technical Reports Server (NTRS)

    Wiseman, S. M.; Avidson, R. E.; Murchie, S.; Poulet, F.; Andrews-Hanna, J. C.; Morris, R. V.; Seelos, F. P.

    2008-01-01

    Several phyllosilicate and hydrated sulfate deposits in Meridiani have been mapped in detail with high resolution MRO CRISM [1] data. Previous studies have documented extensive exposures of outcrop in Meridiani (fig 1), or etched terrain (ET), that has been interpreted to be sedimentary in origin [e.g., 2,3]. These deposits have been mapped at a regional scale with OMEGA data and show enhanced hydration (1.9 m absorption) in several areas [4]. However, hydrated sulfate detections were restricted to valley exposures in northern Meridiani ET [5]. New high resolution CRISM images show that hydrated sulfates are present in several spatially isolated exposures throughout the ET (fig 1). The hydrated sulfate deposits in the valley are vertically heterogeneous with layers of mono and polyhydrated sulfates and are morphologically distinct from other areas of the ET. We are currently mapping the detailed spatial distribution of sulfates and searching for distinct geochemical horizons that may be traced back to differential ground water recharge and/or evaporative loss rates. The high resolution CRISM data has allowed us to map out several phyllosilicate deposits within the fluvially dissected Noachian cratered terrain (DCT) to the south and west of the hematite-bearing plains (Ph) and ET (fig 1). In Miyamoto crater, phyllosilicates are located within 30km of the edge of Ph, which is presumably underlain by acid sulfate deposits similar to those explored by Opportunity. The deposits within this crater may record the transition from fluvial conditions which produced and/or preserved phyllosilicates deposits to a progressively acid sulfate dominated groundwater system in which large accumulations of sulfate-rich evaporites were deposited .

  9. Game of life on phyllosilicates: Gliders, oscillators and still life

    NASA Astrophysics Data System (ADS)

    Adamatzky, Andrew

    2013-10-01

    A phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate automaton is a regular network of finite state machines - silicon nodes and oxygen nodes - which mimics structure of the phyllosilicate. A node takes states 0 and 1. Each node updates its state in discrete time depending on a sum of states of its three (silicon) or six (oxygen) neighbours. Phyllosilicate automata exhibit localisations attributed to Conway's Game of Life: gliders, oscillators, still lifes, and a glider gun. Configurations and behaviour of typical localisations, and interactions between the localisations are illustrated.

  10. Noachian and more recent phyllosilicates in impact craters on Mars

    PubMed Central

    Fairén, Alberto G.; Chevrier, Vincent; Abramov, Oleg; Marzo, Giuseppe A.; Gavin, Patricia; Davila, Alfonso F.; Tornabene, Livio L.; Bishop, Janice L.; Roush, Ted L.; Gross, Christoph; Kneissl, Thomas; Uceda, Esther R.; Dohm, James M.; Schulze-Makuch, Dirk; Rodríguez, J. Alexis P.; Amils, Ricardo; McKay, Christopher P.

    2010-01-01

    Hundreds of impact craters on Mars contain diverse phyllosilicates, interpreted as excavation products of preexisting subsurface deposits following impact and crater formation. This has been used to argue that the conditions conducive to phyllosilicate synthesis, which require the presence of abundant and long-lasting liquid water, were only met early in the history of the planet, during the Noachian period (> 3.6 Gy ago), and that aqueous environments were widespread then. Here we test this hypothesis by examining the excavation process of hydrated minerals by impact events on Mars and analyzing the stability of phyllosilicates against the impact-induced thermal shock. To do so, we first compare the infrared spectra of thermally altered phyllosilicates with those of hydrated minerals known to occur in craters on Mars and then analyze the postshock temperatures reached during impact crater excavation. Our results show that phyllosilicates can resist the postshock temperatures almost everywhere in the crater, except under particular conditions in a central area in and near the point of impact. We conclude that most phyllosilicates detected inside impact craters on Mars are consistent with excavated preexisting sediments, supporting the hypothesis of a primeval and long-lasting global aqueous environment. When our analyses are applied to specific impact craters on Mars, we are able to identify both pre- and postimpact phyllosilicates, therefore extending the time of local phyllosilicate synthesis to post-Noachian times. PMID:20616087

  11. Noachian and more recent phyllosilicates in impact craters on Mars.

    PubMed

    Fairén, Alberto G; Chevrier, Vincent; Abramov, Oleg; Marzo, Giuseppe A; Gavin, Patricia; Davila, Alfonso F; Tornabene, Livio L; Bishop, Janice L; Roush, Ted L; Gross, Christoph; Kneissl, Thomas; Uceda, Esther R; Dohm, James M; Schulze-Makuch, Dirk; Rodríguez, J Alexis P; Amils, Ricardo; McKay, Christopher P

    2010-07-06

    Hundreds of impact craters on Mars contain diverse phyllosilicates, interpreted as excavation products of preexisting subsurface deposits following impact and crater formation. This has been used to argue that the conditions conducive to phyllosilicate synthesis, which require the presence of abundant and long-lasting liquid water, were only met early in the history of the planet, during the Noachian period (> 3.6 Gy ago), and that aqueous environments were widespread then. Here we test this hypothesis by examining the excavation process of hydrated minerals by impact events on Mars and analyzing the stability of phyllosilicates against the impact-induced thermal shock. To do so, we first compare the infrared spectra of thermally altered phyllosilicates with those of hydrated minerals known to occur in craters on Mars and then analyze the postshock temperatures reached during impact crater excavation. Our results show that phyllosilicates can resist the postshock temperatures almost everywhere in the crater, except under particular conditions in a central area in and near the point of impact. We conclude that most phyllosilicates detected inside impact craters on Mars are consistent with excavated preexisting sediments, supporting the hypothesis of a primeval and long-lasting global aqueous environment. When our analyses are applied to specific impact craters on Mars, we are able to identify both pre- and postimpact phyllosilicates, therefore extending the time of local phyllosilicate synthesis to post-Noachian times.

  12. Supercritical CO2 uptake by nonswelling phyllosilicates

    PubMed Central

    Tokunaga, Tetsu K.; Ashby, Paul D.; Kim, Yongman; Voltolini, Marco; Gilbert, Benjamin; DePaolo, Donald J.

    2018-01-01

    Interactions between supercritical (sc) CO2 and minerals are important when CO2 is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO2 alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO2 on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubation with scCO2), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO2 uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO2 partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO2 to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO2, can increase CO2 storage capacity by up to ∼30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO2 uptake constitutes a previously unrecognized potential trapping mechanism. PMID:29339499

  13. Supercritical CO2 uptake by nonswelling phyllosilicates.

    PubMed

    Wan, Jiamin; Tokunaga, Tetsu K; Ashby, Paul D; Kim, Yongman; Voltolini, Marco; Gilbert, Benjamin; DePaolo, Donald J

    2018-01-30

    Interactions between supercritical (sc) CO 2 and minerals are important when CO 2 is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO 2 alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO 2 on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubation with scCO 2 ), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO 2 uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO 2 partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO 2 to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO 2 , can increase CO 2 storage capacity by up to ∼30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO 2 uptake constitutes a previously unrecognized potential trapping mechanism. Copyright © 2018 the Author(s). Published by PNAS.

  14. Supercritical CO 2 uptake by nonswelling phyllosilicates

    DOE PAGES

    Wan, Jiamin; Tokunaga, Tetsu K.; Ashby, Paul D.; ...

    2018-01-16

    Interactions between supercritical (sc) CO 2 and minerals are important when CO 2 is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO 2 alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO 2 on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubationmore » with scCO 2 ), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO 2 uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO 2 partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO 2 to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO 2, can increase CO 2 storage capacity by up to ~30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO 2 uptake constitutes a previously unrecognized potential trapping mechanism.« less

  15. Application of Principal Component Analysis to NIR Spectra of Phyllosilicates: A Technique for Identifying Phyllosilicates on Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Lanza, N. L.

    2012-01-01

    Orbital near-infrared (NIR) reflectance spectra of the martian surface from the OMEGA and CRISM instruments have identified a variety of phyllosilicates in Noachian terrains. The types of phyllosilicates present on Mars have important implications for the aqueous environments in which they formed, and, thus, for recognizing locales that may have been habitable. Current identifications of phyllosilicates from martian NIR data are based on the positions of spectral absorptions relative to laboratory data of well-characterized samples and from spectral ratios; however, some phyllosilicates can be difficult to distinguish from one another with these methods (i.e. illite vs. muscovite). Here we employ a multivariate statistical technique, principal component analysis (PCA), to differentiate between spectrally similar phyllosilicate minerals. PCA is commonly used in a variety of industries (pharmaceutical, agricultural, viticultural) to discriminate between samples. Previous work using PCA to analyze raw NIR reflectance data from mineral mixtures has shown that this is a viable technique for identifying mineral types, abundances, and particle sizes. Here, we evaluate PCA of second-derivative NIR reflectance data as a method for classifying phyllosilicates and test whether this method can be used to identify phyllosilicates on Mars.

  16. Examination of Phyllosilicate-bearing Materials in the Vicinity of the Nili Fossae Using Thermal Infrared Data

    NASA Astrophysics Data System (ADS)

    McDowell, M. L.; Hamilton, V. E.

    2007-07-01

    We examine THEMIS and TES TIR data in areas OMEGA identified as containing phyllosilicates to better understand the spectral characteristics of phyllosilicate-bearing materials and reliable TES detection limits for modeled phyllosilicate abundances.

  17. Phyllosilicate Detection and Uncertainty from Thermal Infrared Data in the Vicinity of the Nili Fossae

    NASA Astrophysics Data System (ADS)

    McDowell, M. L.; Hamilton, V. E.

    2007-03-01

    We examine TIR data from THEMIS and TES in areas identified by OMEGA as containing phyllosilicates. Our investigation will help to constrain phyllosilicate detection limits in TES data and likely surface abundances on Mars.

  18. Diversity of Mineralogy and Occurrences of Phyllosilicates on Mars

    NASA Astrophysics Data System (ADS)

    Clark, R. N.; Swayze, G. A.; Murchie, S. L.; Mustard, J. F.; Milliken, R. E.; Ehlmann, B. L.; McKeown, N. K.; Calvin, W. M.; Wray, J. J.; Bishop, J. L.

    2008-12-01

    Minerals and their occurrences tell us about the chemistry, pressure,and temperatures of past environments, and the possible conditions for past habitability. To date, a fair number of phyllosilicates and other minerals have been detected on Mars (e.g., Poulet et al., Nature v438,p623, 2005; Mustard et al., Nature, v454, p309, 2008; Bishop et al., Science, V321, p830, 2008, and references therein). Minerals and amorphous materials detected and mapped over large areas include kaolinite/halloysite, montmorillonite, Fe/Mg-smectite, nontronite, saponite, chlorite, opal/hydrated glass, illite, muscovite, magnesite, prehnite, olivine, high- and low-calcium pyroxene, hematite, jarosite, alunite, kieserite, gypsum, coquimbite or ferricopiapite, possible szomolnokite and others yet to be identified. Phyllosilicate minerals are generally seen associated with Noachian outcrops and are thought to result from aqueous alteration, perhaps over sustained periods. Poly- and mono-hydrated Mg-sulphates appear to have been formed after the phyllosilicates. The patterns and occurrences of minerals so far mapped do not appear to show classic hydrothermal systems as have been observed on Earth (e.g., Yellowstone, Wyoming, and Cuprite, Nevada). Prehnite, previously identified on Mars as scapolite, a low-temperature phyllosilicate commonly found in mafic volcanics on Earth, appears widespread on Mars, often in association with Fe/Mg-smectite or chlorite. Phyllosilicates are observed in local outcrops, but occur regionally, generally indicating the effects of a common alteration process during the Noachian epoch. The discovery of mineralogies indicating both acidic and alkaline environments using CRISM and OMEGA data show that conditions were locally diverse. If the environments for the regional phyllosilicate deposits are found to be hostile to past habitability, perhaps studying the smaller mineralogically diverse areas may prove more fruitful. This talk will review the minerals and their

  19. Preparation and structural characterization of zwitterionic surfactant intercalated into NiZn-layered hydroxide salts

    NASA Astrophysics Data System (ADS)

    Liu, Jiexiang; Wang, Jianlong; Zhang, Xiaoguang; Fang, Binbin; Hu, Pan; Zhao, Xuyang

    2015-10-01

    Three zwitterionic surfactants, dodecyl dimethyl carboxylbetaine (DCB), dodecyl dimethyl sulfobetaine (DSB) and N-dodecyl-β-aminoprpionate (DAP), intercalated into NiZn-layered hydroxide salts (NZL-DCB, NZL-DSB and NZL-DAP) were synthesized by the coprecipitation method. The effect of surfactant content, pH, temperature and time of hydrothermal treatment on preparation was investigated and discussed. The NZL-DCB, NZL-DSB and NZL-DAP were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry analysis and differential thermal analysis (TGA/DTA). The results showed that basal spacings of NZL-DCB, NZL-DSB and NZL-DAP were around 3.45, 3.68 and 3.94 nm, respectively. DCB, DSB and DAP probably form an overlapped bilayer in the gallery. TGA/DTA data indicated that NZL-DCB, NZL-DSB and NZL-DAP displayed three loss weight stages: loss of adsorbed and structural water, dehydroxylation of matrix and decomposition of nitrate ions, decomposition and combustion of surfactants. Furthermore, chemical analysis data, BET surface area and scanning electron microscopic (SEM) were also measured and analyzed.

  20. Evidence for Phyllosilicates near the Lunar South Pole

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Jensen, E.; Domingue, Deborah; McFadden, L.; Coombs, Cassandraa; Mendell, Wendell

    1998-01-01

    While theoretically water ice could be stable in permanently shadowed areas near the lunar poles, there is conflicting observational evidence for the existence of water ice at either pole. Clementine's bistatic radar resumed a weak signal commensurate with water ice in the South Pole Aitken Basin; however, groundbased radar searches have not detected such a signal at either pole. Lunar Prospector measured large amounts of H (attributed to water) at both poles; however, Galileo near-infrared spectral measurements of the north polar region did not detect the prominent 3.0 micron absorption feature due to interlayer and adsorbed water in phyllosilicates. Evidence for the existence of water at the lunar poles is still ambiguous and controversial. We present evidence, based on the analysis of Galileo SSI images, for the presence of phyllosilicates near the lunar south pole. Using the color image sequence (560 nm, 670 nm, 756 nm, and 889 nm) of Lunmap 14 taken during the Galileo Earth-Moon pass I, we have identified areas that show evidence for a 0.7 microns absorption feature present in Fe-bearing phyllosilicates.

  1. Creep of phyllosilicates at the onset of plate tectonics

    SciT

    Amiguet, Elodie; Reynard, Bruno; Caracas, Razvan

    Plate tectonics is the unifying paradigm of geodynamics yet the mechanisms and causes of its initiation remain controversial. Some models suggest that plate tectonics initiates when the strength of lithosphere is lower than 20-200 MPa, below the frictional strength of lithospheric rocks (>700 MPa). At present-day, major plate boundaries such as the subduction interface, transform faults, and extensional faults at mid-oceanic ridge core complexes indicate a transition from brittle behaviour to stable sliding at depths between 10 and 40 km, in association with water-rock interactions forming phyllosilicates. We explored the rheological behaviour of lizardite, an archetypal phyllosilicate of the serpentinemore » group formed in oceanic and subduction contexts, and its potential influence on weakening of the lithospheric faults and shear zones. High-pressure deformation experiments were carried out on polycrystalline lizardite - the low temperature serpentine variety - using a D-DIA apparatus at a variety of pressure and temperature conditions from 1 to 8 GPa and 150 to 400 C and for strain rates between 10{sup -4} and 10{sup -6} s{sup -1}. Recovered samples show plastic deformation features and no evidence of brittle failure. Lizardite has a large rheological anisotropy, comparable to that observed in the micas. Mechanical results and first-principles calculations confirmed easy gliding on lizardite basal plane and show that the flow stress of phyllosilicate is in the range of the critical value of 20-200 MPa down to depths of about 200 km. Thus, foliated serpentine or chlorite-bearing rocks are sufficiently weak to account for plate tectonics initiation, aseismic sliding on the subduction interface below the seismogenic zone, and weakening of the oceanic lithosphere along hydrothermally altered fault zones. Serpentinisation easing the deformation of the early crust and shallow mantle reinforces the idea of a close link between the occurrence of plate tectonics and

  2. Sulfate Mineral Formation from Acid-Weathered Phyllosilicates: Implications for the Aqueous History of Mars

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.; Morris, R. V.

    2015-01-01

    Phyllosilicates on Mars are thought to have formed under neutral to alkaline conditions during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Gya). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Gya). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the geologic and aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era may have been weathered by the prevailing acidic conditions that characterize the Hesperian. Therefore, the purpose of this study is to characterize the alteration products resulting from acid-sulfate weathered phyllosilicates in laboratory experiments. This study focuses on two phyllosilicates commonly identified with sulfates on Mars: nontronite and saponite. We also compare our results to observations of phyllosilicates and sulfates on Mars to better understand the formation process of sulfates in close proximity to phyllosilicates on Mars and constrain the aqueous conditions of these regions on Mars.

  3. Phyllosilicate emission from protoplanetary disks: is the indirect detection of extrasolar water possible?

    PubMed

    Morris, Melissa A; Desch, Steven J

    2009-12-01

    Phyllosilicates are hydrous minerals formed by interaction between rock and liquid water, and are commonly found in meteorites that originate in the asteroid belt. Collisions between asteroids contribute to zodiacal dust, which therefore reasonably could include phyllosilicates. Collisions between planetesimals in protoplanetary disks may also produce dust that contains phyllosilicates. These minerals possess characteristic emission features in the mid-infrared and could be detectable in extrasolar protoplanetary disks. We have determined whether phyllosilicates in protoplanetary disks are detectable in the infrared, using instruments such as those on board the Spitzer Space Telescope and the Stratospheric Observatory for Infrared Astronomy (SOFIA). We calculated opacities for the phyllosilicates most common in meteorites and, using a two-layer radiative transfer model, computed the emission of radiation from a protoplanetary disk. We found that phyllosilicates present at the 3% level lead to observationally significant differences in disk spectra and should therefore be detectable with the use of infrared observations and spectral modeling. Detection of phyllosilicates in a protoplanetary disk would be diagnostic of liquid water in planetesimals in that disk and would demonstrate similarity to our own Solar System. We also discuss use of phyllosilicate emission to test the "water worlds" hypothesis, which proposes that liquid water in planetesimals should correlate with the inventory of short-lived radionuclides in planetary systems, especially (26)Al.

  4. Structural and Dynamical Properties of 2:1 Phyllosilicates Edges and Nanoparticles

    NASA Astrophysics Data System (ADS)

    Newton, A. G.; Sposito, G.

    2012-12-01

    Classical mechanics simulations of bulk 2:1 phyllosilicate minerals provide atomic scale perspectives of the macroscopic sorption and diffusion phenomena in interlayer nanopores. An equivalent perspective of these interfacial phenomena in macropores bounded by the edges of stacked phyllosilicate particles is not possible due to the absence of a forcefield for the edges of phyllosilicate minerals. A valid forcefield to describe the phyllosilicate edge is essential to link the quantum and continuum mechanical models. The inherently disordered edge of 2:1 phyllosilicate minerals and rarity of well-crystallized samples further complicates the task of validating a forcefield for the phyllosilicate edge. Periodic bond chain theory identifies three tetrahedral-octahedral-tetrahedral (TOT) structures that parallel the edge faces of pseudohexagonal phyllosilicate particles. These TOT structures are the basis of atomistic models of the dominant edge interface and nanoparticles. The CLAYFF forcefield describes all pairwise atomic interactions with only minimal partial charge adjustments to maintain model neutrality, where necessary. Atomistic simulations in the isobaric-isothermal ensemble at nanosecond timescales predict equilibrium edge structures and dynamical properties of the aqueous interface. The CLAYFF forcefield and the limited adjustments to parameters predict edge and particle structures that are consistent with the results of ab initio MD simulations, support macroscopic observations of phyllosilicate reactivity, and provide legitimacy for disordered models of 2:1 phyllosilicates. The heterogeneous edge structures can be explained by the chemistry of the octahedral cation and surface charge anisotropy. In the plane of the octahedral sheet, the cations of the octahedral layer can assume four-, five-, and six-coordinate polyhedral geometries at the edge interface. These disordered edge structures create alternate alignments in the tetrahedral sheet. The structural

  5. Radial Migration of Phyllosilicates in the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Ciesla, F. J.; Lauretta, D. S.; Hood, L. L.

    2004-01-01

    It has long been recognized that the high temperatures of the inner solar nebula (within approx. 3 AU) would not have allowed water to be incorporated into solids. However, the presence of water on the surface of Earth, as well as evidence for it on the surface of an early Mars imply that water was incorporated into solid bodies in this region. How this water was delivered to the solid bodies has yet to be identified. In this abstract we explore the possibility that hydrous minerals, such as phyllosilicates, formed somewhere in the asteroid belt region of the solar nebula or beyond, and then migrated inward where they would be accreted into larger bodies.

  6. Evidence of Phyllosilicate in Wooly Patch+: An Altered Rock Encountered on the Spirit Rover Traverse

    NASA Technical Reports Server (NTRS)

    Wang, Alian; Haskin, Larry A.; Korotev, Randy L.; Jolliff, Brad L.; deSouza, Paulo, Jr.; Kusack, Alastair G.

    2005-01-01

    In the course of examining rocks along the traverse of the Spirit rover toward the Columbia Hills [1, 9], we noticed that the chemistry of a rock named "Wooly Patch" was neither basaltic as the rocks near the landing site [8] nor slightly altered basalt inferred from regolith in plains trenches [10]. The major cation ratios appear to match those of phyllosilicates [11]. The presence of phyllosilicate minerals on Mars has been predicted [12]; reasons for the rarity or absence of phyllosilicates have also been discussed [13]. We have thus done as detailed an analysis of Wooly Patch as the data enable, which suggests phyllosilicates of kaolinite, serpentine, and chlorite types, plus some feldspar and pyroxene are prime candidates to constitute Wooly Patch.

  7. Micromechanics of Friction in a Detailed Study of Mg-rich Phyllosilicates

    NASA Astrophysics Data System (ADS)

    Sanchez Roa, C.; Faulkner, D.; Boulton, C. J.; Jimenez Millan, J.; Nieto, F.

    2016-12-01

    Phyllosilicate minerals commonly occur within faults, which may accommodate slip either aseismically via creep mechanisms or seismically in earthquakes. The Mg-rich phyllosilicates talc, saponite, sepiolite, and palygorskite have different crystallography and habits. Sepiolite and palygorskite are fibrous due to their discontinuous tetrahedral layers, while saponite and talc are platy due to the continuity of their TOT and water layers. Friction experiments were conducted in a triaxial apparatus under 95 MPa effective normal stress with water and argon as pore fluids. Results show a marked contrast between friction coefficients of fibrous phyllosilicates, 0.57 to 0.63 for argon experiments and 0.4 to 0.5 for water-saturated experiments, and platy Mg-rich phyllosilicates, as low as 0.22 for argon experiments and 0.04 for water-saturated experiments. During velocity steps (where sliding velocity is increased or decreased by one order of magnitude), the two mineral groups exhibit distinctly dissimilar behaviours. After the direct effect of the change in sliding rate, fibrous phyllosilicates show a rapid exponential decay towards a new friction coefficient (a positive b value). Meanwhile, the friction coefficient of the platy phyllosilicates has a more linear evolution (a zero, or negative b value). This effect could be related to a difference in the sliding strength of the contact asperities which would be much higher for crystal surfaces of fibrous minerals with an indented surface due to the silicon tetrahedra inversions. The fibre-shaped crystals may consequently require higher amounts of volumetric work against the normal stress (dilatancy). SEM and TEM observations of the deformed samples showed a well-developed network of R1 Riedel shears in the fibrous materials; planar phyllosilicates show a more homogeneous matrix and incipient development of P foliation. Planar phyllosilicate grains align on their basal planes facilitating intergranular sliding, in contrast

  8. Insights Into the Aqueous History of Mars from Acid-Sulfate Weathered Phyllosilicates

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.; Morris, R. V.

    2016-01-01

    Phyllosilicates on Mars are thought to have formed during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Ga). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Ga). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era would have been weathered by the prevailing acidic conditions that define the Hesperian. Therefore, the purpose of this study is to characterize the alteration products of acid-sulfate weathered phyllosilicates in laboratory experiments, focusing on the Fe/Mg-smectites commonly identified on Mars. We also compare our results to observations of phyllosilicates and sulfates on Mars in regions such as Endeavour Crater and Mawrth Vallis to understand the formation process of sulfates and constrain the aqueous history of these regions.

  9. One-dimensional filtration of pharmaceutical grade phyllosilicate dispersions.

    PubMed

    Viseras, C; Cerezo, P; Meeten, G H; Lopez-Galindo, A

    2001-04-17

    The filtration behaviour of some clay-water dispersions was studied. Two Spanish fibrous phyllosilicates (sepiolite from Vicálvaro and palygorskite from Turón) and a commercial bentonite (Bentopharm UK) with similar sizes and different morphologies (fibrous and/or laminar) were selected as model clays. Sepiolite from Vicálvaro is an almost pure fibrous sample, Bentopharm presents a high amount of laminar particles and palygorskite from Turón is made up of similar percentages of laminar and fibrous particles. The disperse systems were made up using a rotor-stator mixer working at two different mixing rates (1000 and 8000 rpm), for periods of 1 and 10 min. Filtration measurements were taken and the corresponding filtration curves obtained. Finally, the desorptivity (S) of the filtration cakes was calculated and correlated to the textural characteristics of the materials, the solid fraction and mixing conditions. Filtration behaviour of the dispersions depended on all three of these factors. Laminar dispersions presented lower S values than fibrous dispersions. In the 2% w/v dispersions the bridging forces between particles did not permit formation of an interconnected network as in 10% w/v dispersions and, consequently, filtration times increased with the solid fraction (i.e. S values decreased). Regarding stability to pH changes, the results showed that filtration behaviour was highly sensitive to basic pH in the fibrous clay dispersions and almost insensitive in the laminar clay dispersions.

  10. Application of an alkylammonium method for characterization of phyllosilicates in CI chondrites

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Zolensky, M. E.; Yang, S. V.

    1994-01-01

    Many meteorites and interplanetary dust particles (IDP's) with primitive compositions contain significant amounts of phyllosilicates, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period in the solar system. These meteorites are chondrites of the carbonaceous and ordinary varieties. Characterization of phyllosilicates in these materials is important because of the important physico-chemical information they hold, e.g., from well characterized phyllosilicates, thermodynamic stability relations and hence the conditions of formation of phyllosilicates in the parent body of the meteorite can be predicted. Although we are at a rudimentary level of understanding of the minerals resulting from the aqueous alteration in the early solar nebula, we know that the most common phyllosilicates present in chondritic extraterrestrial materials are serpentines, smectites, chlorites, and micas. The characterization of fine grained minerals in meteorites and IDP's rely heavily on electron beam instruments, especially transmission electron microscopy (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction analysis, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites loose their interlayer water and the interlayers collapse to the same basal spacing as mica in the high vacuum of the TEM. In high-resolution TEM (HRTEM) images, smectite basal spacings vary from 1 nm up to 1.5 nm, while micas show 1 or 2 nm basal spacings. Not only is it difficult to differentiate smectites from micas, but there is no way of identifying different classes of smectites in meteorites and IDP's. To differentiate smectites from micas and also to recognize the charge differences among smectites, an alkylammonium method can be employed because the basal spacings of alkylammonium saturated smectites expand as a function of alkylamine chain

  11. Biotite Comminution in Phyllosilicate Rich Mylonites: Microstructural and Nanostructural Observations

    NASA Astrophysics Data System (ADS)

    Aslin, J.; Mariani, E.; Dawson, K.

    2017-12-01

    Micas are one of the most important mineral groups with regard to the strength and rheology of the Earth's crust. This is a result of their distinct weakness relative to other silicate phases coupled with their generally high abundance at mid-crustal conditions. Despite this, relatively little is known regarding the mechanisms of viscous deformation in micas. The samples used in this study were collected from the Cossato-Mergozzo-Brissago (C-M-B) line, an amphibolite facies mylonitic shear zone in Northern Italy. The granitoid and metasedimentary protoliths of this 100 -150 m wide shear zone ensure a high but variable phyllosilicate content within predominantly quartzofelspathic lithologies. Initial microstructural analysis using optical and scanning electron microscopy (SEM) reveals a significant change in biotite deformation behaviour with increasing strain. At low strains kinking and basal glide dominate, however at higher strain biotite undergoes a dramatic grain size reduction which is at first concentrated along grain edges and kink band boundaries but later involves the entire grain. In the highest strain samples examined, biotite only survives as a component of a very fine grained matrix. In contrast, muscovite, also present in these rocks, remains coarse, forming kinked and bent mica fish even to high strains. The comminution of biotite is of critical importance to the microstructural evolution of these mylonites as it facilitates the development of an interconnected network of fine and potentially very weak grains. However, the mechanism responsible is not clear. We use transmission electron microscopy (TEM) to observe and characterise the intracrystalline structure of the biotite in these samples both prior to and after this grain size reduction has taken place. A better understanding of the nano-scale microstructures produced by natural deformation in micas will aid in determining the mechanisms which control the way these important crustal minerals

  12. Implications of Martian Phyllosilicate Formation Conditions to the Early Climate on Mars

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Baker, L.; Fairén, A. G.; Michalski, J. R.; Gago-Duport, L.; Velbel, M. A.; Gross, C.; Rampe, E. B.

    2017-12-01

    We propose that short-term warmer and wetter environments, occurring sporadically in a generally cold early Mars, enabled formation of phyllosilicate-rich outcrops on the surface of Mars without requiring long-term warm and wet conditions. We are investigating phyllosilicate formation mechanisms including CO2 and H2O budgets to provide constraints on the early martian climate. We have evaluated the nature and stratigraphy of phyllosilicate-bearing surface units on Mars based on i) phyllosilicate-forming environments on Earth, ii) phyllosilicate reactions in the lab, and iii) modeling experiments involving phyllosilicates and short-range ordered (SRO) materials. The type of phyllosilicates that form on Mars depends on temperature, water/rock ratio, acidity, salinity and available ions. Mg-rich trioctahedral smectite mixtures are more consistent with subsurface formation environments (crustal, hydrothermal or alkaline lakes) up to 400 °C and are not associated with martian surface environments. In contrast, clay profiles dominated by dioctahedral Al/Fe-smectites are typically formed in subaqueous or subaerial surface environments. We propose models describing formation of smectite-rich outcrops and laterally extensive vertical profiles of Fe/Mg-smectites, sulfates, and Al-rich clay assemblages formed in surface environments. Further, the presence of abundant SRO materials without phyllosilicates could mark the end of the last warm and wet episode on Mars supporting smectite formation. Climate Implications for Early Mars: Clay formation reactions proceed extremely slowly at cool temperatures. The thick smectite outcrops observed on Mars through remote sensing would require standing water on Mars for hundreds of millions of years if they formed in waters 10-15 °C. However, warmer temperatures could have enabled faster production of these smectite-rich beds. Sporadic warming episodes to 30-40 °C could have enabled formation of these smectites over only tens or

  13. Spectroscopic study of the dehydration and/or dehydroxylation of phyllosilicate and zeolite minerals

    NASA Astrophysics Data System (ADS)

    Che, Congcong; Glotch, Timothy D.; Bish, David L.; Michalski, Joseph R.; Xu, Wenqian

    2011-05-01

    Phyllosilicates on Mars mapped by infrared spectroscopic techniques could have been affected by dehydration and/or dehydroxylation associated with chemical weathering in hyperarid conditions, volcanism or shock heating associated with meteor impact. The effects of heat-induced dehydration and/or dehydroxylation on the infrared spectra of 14 phyllosilicates from four structural groups (kaolinite, smectite, sepiolite-palygorskite, and chlorite) and two natural zeolites are reported here. Pressed powders of size-separated phyllosilicate and natural zeolite samples were heated incrementally from 100°C to 900°C, cooled to room temperature, and measured using multiple spectroscopic techniques: midinfrared (400-4000 cm-1) attenuated total reflectance, midinfrared reflectance (400-1400 cm-1), and far-infrared reflectance (50-600 cm-1) spectroscopies. Correlated thermogravimetric analysis and X-ray diffraction data were also acquired in order to clarify the thermal transformation of each sample. For phyllosilicate samples, the OH stretching (˜3600 cm-1), OH bending (˜590-950 cm-1), and/or H2O bending (˜1630 cm-1) bands all become very weak or completely disappear upon heating to temperatures > 500°C. The spectral changes associated with SiO4 vibrations (˜1000 cm-1 and ˜500 cm-1) show large variations depending on the compositions and structures of phyllosilicates. The thermal behavior of phyllosilicate IR spectra is also affected by the type of octahedral cations. For example, spectral features of Al3+-rich smectites are more stable than those of Fe3+-rich smectites. The high-temperature (>800°C) spectral changes of trioctahedral Mg2+-rich phyllosilicates such as hectorite, saponite, and sepiolite result primarily from crystallization of enstatite. Phyllosilicates with moderate Mg2+ concentration (e.g., palygorskite, clinochlore) and dioctahedral montmorillonites (e.g., SAz-1 and SCa-3) with partial Mg2+-for-Al3+ substitution all have new spectral feature developed

  14. Hydrothermal Synthesis and Characterization of Ni-Al Montmorillonite-Like Phyllosilicates

    PubMed Central

    Reinholdt, Marc X.; Brendlé, Jocelyne; Tuilier, Marie-Hélène; Kaliaguine, Serge; Ambroise, Emmanuelle

    2013-01-01

    This work describes the first hydrothermal synthesis in fluoride medium of Ni-Al montmorillonite-like phyllosilicates, in which the only metallic elements in the octahedral sheet are Ni and Al. X-ray diffraction , chemical analysis, thermogravimetric and differential thermal analysis, scanning electron microscopy and transmission electron microscopy confirm that the synthesized samples are montmorillonite-like phyllosilicates having the expected chemical composition. The specific surface areas of the samples are relatively large (>100 m2 g−1) compared to naturally occurring montmorillonites. 29Si and 27Al nuclear magnetic resonance (NMR) indicate substitutions of Al for Si in the tetrahedral sheet. 19F NMR and Ni K-edge extended X-ray absorption fine structure (EXAFS) local probes highlight a clustering of the metal elements and of the vacancies in the octahedral sheet of the samples. These Ni-Al phyllosilicates exhibit a higher local order than in previously synthesized Zn-Al phyllosilicates. Unlike natural montmorillonites, where the distribution of transition metal cations ensures a charge equilibrium allowing a stability of the framework, synthetic montmorillonites entail clustering and instability of the lattice when the content of divalent element in the octahedral sheet exceeds ca. 20%. Synthesis of Ni-Al montmorillonite-like phyllosilicates, was successfully achieved for the first time. These new synthetic materials may find potential applications as catalysts or as materials with magnetic, optical or staining properties. PMID:28348321

  15. Phyllosilicate and sulfate-hematite deposits within Miyamoto crater in Southern Sinus Meridiani, Mars

    Wiseman, S.M.; Arvidson, R. E.; Andrews-Hanna, J. C.; Clark, R.N.; Lanza, N.L.; des Marais, D.; Marzo, G.A.; Morris, R.V.; Murchie, S.L.; Newsom, Horton E.; Noe Dobrea, E.Z.; Ollila, A.M.; Poulet, F.; Roush, T.L.; Seelos, F.P.; Swayze, G.A.

    2008-01-01

    Orbital topographic, image, and spectral data show that sulfate- and hematite-bearing plains deposits similar to those explored by the MER rover Opportunity unconformably overlie the northeastern portion of the 160 km in diameter Miyamoto crater. Crater floor materials exhumed to the west of the contact exhibit CRISM and OMEGA NIR spectral signatures consistent with the presence of Fe/Mg-rich smectite phyllosilicates. Based on superposition relationships, the phyllosilicate-bearing deposits formed either in-situ or were deposited on the floor of Miyamoto crater prior to the formation of the sulfate-rich plains unit. These findings support the hypothesis that neutral pH aqueous conditions transitioned to a ground-water driven acid sulfate system in the Sinus Meridiani region. The presence of both phyllosilicate and sulfate- and hematite-bearing deposits within Miyamoto crater make it an attractive site for exploration by future rover missions. Copyright 2008 by the American Geophysical Union.

  16. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  17. Emplacement of Widespread Fe/Mg Phyllosilicate Layer in West Margaritifer Terra, Mars

    NASA Astrophysics Data System (ADS)

    Seelos, K. D.; Maxwell, R. E.; Seelos, F. P.; Buczkowski, D.; Viviano-Beck, C. E.

    2017-12-01

    West Margaritifer Terra is located at the eastern end of Valles Marineris at the complex intersection of chaos terrains, cratered highlands, and multiple generations of outflow channels. Adjacent regions host layered phyllosilicates thought to indicate early Mars pedogenic and/or ground water-based alteration (e.g., Le Deit et al., 2012), and indeed, hydrologic modeling supports prolonged aqueous activity in the Noachian and Hesperian eras (Andrews-Hanna and Lewis, 2011). The remnant high-standing plateaus in West Margaritifer (0-15°S, 325-345°E) host numerous phyllosilicate-bearing outcrops as well and are the focus of this study. Here, we performed a systematic mapping and characterization of mineralogy and morphology of these deposits in order to assess similarity to other layered phyllosilicates and evaluate potential formation mechanisms. Utilizing multiple remote sensing datasets, we identified three types of phyllosilicate exposures distributed throughout the region: 1) along upper chaos fracture walls, 2) in erosional windows on the plains, and 3) in crater walls and ejecta. Outcrops are spectrally indicative of Fe/Mg smectite (most similar to saponite) and only rare, isolated occurrences of Al-phyllosilicate were observed. Morphologically, the layer is a few to 10 m thick, light-toned, polygonally fractured at decameter scales, and vertical subparallel banding is evident in places. These characteristics were used along with spatial distribution, elevation, and geologic context to evaluate 4 potential formation mechanisms: fluvio-lacustrine, pedogenesis, diagenesis, and hydrothermal alteration. We find that the widespread distribution and spectral homogeneity of the layer favors formation via groundwater alteration and/or pedogenic weathering. This is consistent with interpretations of similar layered phyllosilicates in NW Noachis Terra and the Valles Marineris plains to the west, and significantly extends the area over which these aqueous processes

  18. Characterizing the Phyllosilicate Component of the Sheepbed Mudstone in Gale Crater, Mars Using Laboratory XRD and EGA

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Ming, D. W.; Archer, P. D.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Blake, D. F.; Bristow, T. F.; Sutter, B.; hide

    2014-01-01

    The Curiosity rover investigated the mineralogy of the Sheepbed mudstone member of the Yellowknife Bay formation in Gale crater. Data from the Chemistry and Mineralogy (CheMin) X-ray diffractometer (XRD) helped identify phyllosilicates in the two drilled samples, John Klein and Cumberland. These patterns showed peaks at low angles, consistent with (001) peaks in 2:1 swelling phyllosilicates [1]. Evolved gas analyses (EGA) by the Sample Analysis at Mars (SAM) instrument of these samples confirmed the presence of phyllosilicates through the release of H2O at high temperatures, consistent with dehydroxylation of octahedral OH in phyllosilicates [2]. CheMin data for the phyllosilicates at John Klein and Cumberland show that they are structurally similar in that their (02l) peaks are near 22.5 deg 2theta, suggesting both samples contain trioctahedral 2:1 phyllosilicates [1]. However, the positions of the (001) peaks differ: the phyllosilicate at John Klein has its (001) peak at 10 Angstroms, whereas the phyllosilicate at Cumberland has an (001) peak at 14 Angstroms. Such differences in (001) dspacings can be ascribed to the type of cation in the interlayer site [3]. For example, large monovalent cations (e.g., K(+)) have low hydration energies and readily lose their H2O of hydration, whereas small divalent cations (e.g., Mg(2+)) have high energies of hydration and retain H2O in the phyllosilicate interlayers [3,4]. The goal of this study is to determine whether differences in the interlayer cation composition can explain the CheMin data from John Klein and Cumberland and to use this knowledge to better understand phyllosilicate formation mechanisms.

  19. Stepped fans and facies-equivalent phyllosilicates in Coprates Catena, Mars

    NASA Astrophysics Data System (ADS)

    Grindrod, P. M.; Warner, N. H.; Hobley, D. E. J.; Schwartz, C.; Gupta, S.

    2018-06-01

    Stepped fan deposits and phyllosilicate mineralogies are relatively common features on Mars but have not previously been found in association with each other. Both of these features are widely accepted to be the result of aqueous processes, but the assumed role and nature of any water varies. In this study we have investigated two stepped fan deposits in Coprates Catena, Mars, which have a genetic link to light-toned material that is rich in Fe-Mg phyllosilicate phases. Although of different sizes and in separate, but adjacent, trough-like depressions, we identify similar features at these stepped fans and phyllosilicates that are indicative of similar formation conditions and processes. Our observations of the overall geomorphology, mineralogy and chronology of these features are consistent with a two stage formation process, whereby deposition in the troughs first occurs into shallow standing water or playas, forming fluvial or alluvial fans that terminate in delta deposits and interfinger with interpreted lacustrine facies, with a later period of deposition under sub-aerial conditions, forming alluvial fan deposits. We suggest that the distinctive stepped appearance of these fans is the result of aeolian erosion, and is not a primary depositional feature. This combined formation framework for stepped fans and phyllosilicates can also explain other similar features on Mars, and adds to the growing evidence of fluvial activity in the equatorial region of Mars during the Hesperian and Amazonian.

  20. The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

    DOE PAGES

    Wozniakiewicz, Penelope J.; Ishii, Hope A.; Kearsley, Anton T.; ...

    2015-11-05

    Comet 81P/Wild 2 samples returned by NASA's Stardust mission provide an unequalled opportunity to study the contents of, and hence conditions and processes operating on, comets. They can potentially validate contentious interpretations of cometary infrared spectra and in situ mass spectrometry data: specifically the identification of phyllosilicates and carbonates. However, Wild 2 dust was collected via impact into capture media at ~6 km s -1, leading to uncertainty as to whether these minerals were captured intact, and, if subjected to alteration, whether they remain recognizable. Here, we simulated Stardust Al foil capture conditions using a two-stage light-gas gun, and directlymore » compared transmission electron microscope analyses of pre- and postimpact samples to investigate survivability of lizardite and cronstedtite (phyllosilicates) and calcite (carbonate). We find the phyllosilicates do not survive impact as intact crystalline materials but as moderately to highly vesiculated amorphous residues lining resultant impact craters, whose bulk cation to Si ratios remain close to that of the impacting grain. Closer inspection reveals variation in these elements on a submicron scale, where impact-induced melting accompanied by reducing conditions (due to the production of oxygen scavenging molten Al from the target foils) has resulted in the production of native silicon and Fe- and Fe-Si-rich phases. In contrast, large areas of crystalline calcite are preserved within the calcite residue, with smaller regions of vesiculated, Al-bearing calcic glass. Unambiguous identification of calcite impactors on Stardust Al foil is therefore possible, while phyllosilicate impactors may be inferred from vesiculated residues with appropriate bulk cation to Si ratios. Finally, we demonstrate that the characteristic textures and elemental distributions identifying phyllosilicates and carbonates by transmission electron microscopy can also be observed by state

  1. Spectral characteristics of iron-bearing phyllosilicates: Comparison to Orgueil (CI1), Murchison and Murray (CM2)

    Calvin, W.M.; King, T.V.V.

    1997-01-01

    Phyllosilicate alteration minerals are commonly found in low petrologic types of carbonaceous chondrites. Previous spectral studies have examined Mg-bearing phyllosilicates with limited success in matching the spectral properties of CM and CI chondrites. Transmission electron microscope and other analytical techniques suggest that Fe-bearing clays are more abundant in CI and CM chondrites than magnesian varieties. Here, we present the results of an examination of the reflectance spectra of Fe-phyllosilicates, including serpentines and berthierines, of which the latter were formerly known as septechlorites. We have measured the diffuse reflectance spectra of powdered samples from 0.3 to 25 ??m. We find that these minerals provide a better spectral match to many of the features seen in CI and CM chondrites, and simple linear combinations of the spectra of both Fe- and Mg-phyllosilicates closely approximate the spectra of CM and CI chondrites.

  2. Unraveling the Diversity of Early Aqueous Environments and Climate on Mars Through the Phyllosilicate Record

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Baker, L. L.; Fairén, A. G.; Gross, C.; Velbel, M. A.; Rampe, E. B.; Michalski, J. R.

    2017-01-01

    Were Martian phyllosilicates formed on the surface or subsurface? Was early Mars warm or cold? How long was liquid water present on the surface of Mars? These are some of the many open questions about our neighboring planet. We propose that the mineralogy of the clay-bearing outcrops on Mars can help address these questions. Abundant phyllosilicates and aqueous minerals are observed nearly everywhere we can see the ancient rocks on Mars. Most bountiful among these is Fe/Mg-smectite. In this study we evaluate the nature and stratigraphy of clay outcrops observed on Mars and the presence of mixtures of other clays or other minerals with the ubiquitous Fe/Mg-smectite.

  3. Fe-phyllosilicate redox cycling organisms from a redox transition zone in Hanford 300 Area sediments.

    PubMed

    Benzine, Jason; Shelobolina, Evgenya; Xiong, Mai Yia; Kennedy, David W; McKinley, James P; Lin, Xueju; Roden, Eric E

    2013-01-01

    Microorganisms capable of reducing or oxidizing structural iron (Fe) in Fe-bearing phyllosilicate minerals were enriched and isolated from a subsurface redox transition zone at the Hanford 300 Area site in eastern Washington, USA. Both conventional and in situ "i-chip" enrichment strategies were employed. One Fe(III)-reducing Geobacter (G. bremensis strain R1, Deltaproteobacteria) and six Fe(II) phyllosilicate-oxidizing isolates from the Alphaproteobacteria (Bradyrhizobium japonicum strains 22, is5, and in8p8), Betaproteobacteria (Cupriavidus necator strain A5-1, Dechloromonas agitata strain is5), and Actinobacteria (Nocardioides sp. strain in31) were recovered. The G. bremensis isolate grew by oxidizing acetate with the oxidized form of NAu-2 smectite as the electron acceptor. The Fe(II)-oxidizers grew by oxidation of chemically reduced smectite as the energy source with nitrate as the electron acceptor. The Bradyrhizobium isolates could also carry out aerobic oxidation of biotite. This is the first report of the recovery of a Fe(II)-oxidizing Nocardioides, and to date only one other Fe(II)-oxidizing Bradyrhizobium is known. The 16S rRNA gene sequences of the isolates were similar to ones found in clone libraries from Hanford 300 sediments and groundwater, suggesting that such organisms may be present and active in situ. Whole genome sequencing of the isolates is underway, the results of which will enable comparative genomic analysis of mechanisms of extracellular phyllosilicate Fe redox metabolism, and facilitate development of techniques to detect the presence and expression of genes associated with microbial phyllosilicate Fe redox cycling in sediments.

  4. Energetic features of copper and lead sorption by innovative aminoalcohol-functionalized cobalt phyllosilicates.

    PubMed

    Melo, Maurício Alves; Airoldi, Claudio

    2010-11-14

    Inorganic-organic cobalt phyllosilicate hybrids were synthesized by the sol-gel procedure under mild non-hydrothermal conditions with a silicon precursor, formed through individual reactions between the silane 3-glycidoxypropyltriethoxysilane and the aminoalcohols ethanol- or diethanolamine. These procedures generated talc-like phyllosilicates containing pendant organic chains with nitrogen and oxygen basic centres located in the interlamellar region. For organofunctionalized phyllosilicates the lamellar structure obtained through the sol-gel method was confirmed by X-ray powder diffraction, while elemental analysis indicated that the densities of the organic groups attached to the new matrices were 3.31 ± 0.05 and 3.08 ± 0.07 mmol g(-1) for hybrids functionalized with ethanol- and diethanolamines, respectively. Infrared spectroscopy and nuclear magnetic resonance in the solid state for (13)C and (29)Si showed that the organic groups are indeed covalently bonded to the inorganic structures and the process of functionalization did not affect the original structures of the silylating agents employed. The thermally stable hybrids presented well-formed particles with a homogeneous distribution of cobalt and nitrogen atoms. Their abilities for copper removal from aqueous solutions gave maximum capacities of sorption of 2.01 ± 0.11 and 2.55 ± 0.15 mmol g(-1) for phyllosilicates containing ethanol- and diethanolamine groups, respectively. For lead sorption the values of 2.59 ± 0.11 and 2.43 ± 0.12 mmol g(-1) were found for this same sequence. These sorption data were adjusted to the non-linear regression of the Langmuir equation. Energetic features related to the interactions between the cations and the pendant basic centres were determined through calorimetric titrations. The acid-basic interactions reflect the spontaneity of the reactions, which are also enthalpically and entropically favourable for these chelating processes at the solid-liquid interface.

  5. Early geochemical environment of Mars as determined from thermodynamics of phyllosilicates.

    PubMed

    Chevrier, Vincent; Poulet, Francois; Bibring, Jean-Pierre

    2007-07-05

    Images of geomorphological features that seem to have been produced by the action of liquid water have been considered evidence for wet surface conditions on early Mars. Moreover, the recent identification of large deposits of phyllosilicates, associated with the ancient Noachian terrains suggests long-timescale weathering of the primary basaltic crust by liquid water. It has been proposed that a greenhouse effect resulting from a carbon-dioxide-rich atmosphere sustained the temperate climate required to maintain liquid water on the martian surface during the Noachian. The apparent absence of carbonates and the low escape rates of carbon dioxide, however, are indicative of an early martian atmosphere with low levels of carbon dioxide. Here we investigate the geochemical conditions prevailing on the surface of Mars during the Noachian period using calculations of the aqueous equilibria of phyllosilicates. Our results show that Fe3+-rich phyllosilicates probably precipitated under weakly acidic to alkaline pH, an environment different from that of the following period, which was dominated by strongly acid weathering that led to the sulphate deposits identified on Mars. Thermodynamic calculations demonstrate that the oxidation state of the martian surface was already high, supporting early escape of hydrogen. Finally, equilibrium with carbonates implies that phyllosilicate precipitation occurs preferentially at a very low partial pressure of carbon dioxide. We suggest that the possible absence of Noachian carbonates more probably resulted from low levels of atmospheric carbon dioxide, rather than primary acidic conditions. Other greenhouse gases may therefore have played a part in sustaining a warm and wet climate on the early Mars.

  6. Fe-phyllosilicate redox cycling organisms from a redox transition zone in Hanford 300 Area sediments

    PubMed Central

    Benzine, Jason; Xiong, Mai Yia; Kennedy, David W.; McKinley, James P.; Lin, Xueju; Roden, Eric E.

    2013-01-01

    Microorganisms capable of reducing or oxidizing structural iron (Fe) in Fe-bearing phyllosilicate minerals were enriched and isolated from a subsurface redox transition zone at the Hanford 300 Area site in eastern Washington, USA. Both conventional and in situ “i-chip” enrichment strategies were employed. One Fe(III)-reducing Geobacter (G. bremensis strain R1, Deltaproteobacteria) and six Fe(II) phyllosilicate-oxidizing isolates from the Alphaproteobacteria (Bradyrhizobium japonicum strains 22, is5, and in8p8), Betaproteobacteria (Cupriavidus necator strain A5-1, Dechloromonas agitata strain is5), and Actinobacteria (Nocardioides sp. strain in31) were recovered. The G. bremensis isolate grew by oxidizing acetate with the oxidized form of NAu-2 smectite as the electron acceptor. The Fe(II)-oxidizers grew by oxidation of chemically reduced smectite as the energy source with nitrate as the electron acceptor. The Bradyrhizobium isolates could also carry out aerobic oxidation of biotite. This is the first report of the recovery of a Fe(II)-oxidizing Nocardioides, and to date only one other Fe(II)-oxidizing Bradyrhizobium is known. The 16S rRNA gene sequences of the isolates were similar to ones found in clone libraries from Hanford 300 sediments and groundwater, suggesting that such organisms may be present and active in situ. Whole genome sequencing of the isolates is underway, the results of which will enable comparative genomic analysis of mechanisms of extracellular phyllosilicate Fe redox metabolism, and facilitate development of techniques to detect the presence and expression of genes associated with microbial phyllosilicate Fe redox cycling in sediments. PMID:24379809

  7. Isolation of phyllosilicate-iron redox cycling microorganisms from an illite-smectite rich hydromorphic soil.

    PubMed

    Shelobolina, Evgenya; Konishi, Hiromi; Xu, Huifang; Benzine, Jason; Xiong, Mai Yia; Wu, Tao; Blöthe, Marco; Roden, Eric

    2012-01-01

    The biogeochemistry of phyllosilicate-Fe redox cycling was studied in a Phalaris arundinacea (reed canary grass) dominated redoximorphic soil from Shovelers Sink, a small glacial depression near Madison, WI. The clay size fraction of Shovelers Sink soil accounts for 16% of the dry weight of the soil, yet contributes 74% of total Fe. The dominant mineral in the clay size fraction is mixed layer illite-smectite, and in contrast to many other soils and sediments, Fe(III) oxides are present in low abundance. We examined the Fe biogeochemistry of Shovelers Sink soils, estimated the abundance of Fe redox cycling microorganisms, and isolated in pure culture representative phyllosilicate-Fe oxidizing and reducing organisms. The abundance of phyllosilicate-Fe reducing and oxidizing organisms was low compared to culturable aerobic heterotrophs. Both direct isolation and dilution-to-extinction approaches using structural Fe(II) in Bancroft biotite as a Fe(II) source, and O(2) as the electron acceptor, resulted in recovery of common rhizosphere organisms including Bradyrhizobium spp. and strains of Cupriavidus necator and Ralstonia solanacearum. In addition to oxidizing biotite and soluble Fe(II) with O(2), each of these isolates was able to oxidize Fe(II) in reduced NAu-2 smectite with [Formula: see text] as the electron acceptor. Oxidized NAu-2 smectite or amorphous Fe(III) oxide served as electron acceptors for enrichment and isolation of Fe(III)-reducing microorganisms, resulting in recovery of a strain related to Geobacter toluenoxydans. The ability of the recovered microorganisms to cycle phyllosilicate-Fe was verified in an experiment with native Shovelers Sink clay. This study confirms that Fe in the native Shovelers Sink clay is readily available for microbial redox transformation and can be cycled by the Fe(III)-reducing and Fe(II)-oxidizing microorganisms recovered from the soil.

  8. Reactivity of iron-rich phyllosilicates with uranium and chromium through redox transition zones

    SciT

    Burgos, William D.

    This project performed thermodynamic, kinetic, and mineral structural studies on the reactivity of phyllosilicate Fe(II/III) with metal-reducing bacteria, and with two important poly-valent DOE contaminants (chromium and uranium) that show high mobility in their oxidized state. We focused on Fe-bearing phyllosilicates because these are important components of the reactive, fines fraction of Hanford, Oak Ridge, and Idaho National Laboratory sediments. Iron-bearing phyllosilicates strongly influence the redox state and mobility of Cr and U because of their limited hydraulic conductivity, high specific surface area, and redox reactivity. This was a collaborative project between Penn State (W.D. Burgos – PI), Miami Universitymore » (H. Dong – Co-PI), and Argonne National Laboratory (K. Kemner and M. Boyanov – Co-PIs). Penn State and Miami University were funded together but separately from ANL. This report summarizes research findings and publications produced by Penn State and Miami University.« less

  9. Ammoniated phyllosilicates with a likely outer Solar System origin on (1) Ceres.

    PubMed

    De Sanctis, M C; Ammannito, E; Raponi, A; Marchi, S; McCord, T B; McSween, H Y; Capaccioni, F; Capria, M T; Carrozzo, F G; Ciarniello, M; Longobardo, A; Tosi, F; Fonte, S; Formisano, M; Frigeri, A; Giardino, M; Magni, G; Palomba, E; Turrini, D; Zambon, F; Combe, J-P; Feldman, W; Jaumann, R; McFadden, L A; Pieters, C M; Prettyman, T; Toplis, M; Raymond, C A; Russell, C T

    2015-12-10

    Studies of the dwarf planet (1) Ceres using ground-based and orbiting telescopes have concluded that its closest meteoritic analogues are the volatile-rich CI and CM carbonaceous chondrites. Water in clay minerals, ammoniated phyllosilicates, or a mixture of Mg(OH)2 (brucite), Mg2CO3 and iron-rich serpentine have all been proposed to exist on the surface. In particular, brucite has been suggested from analysis of the mid-infrared spectrum of Ceres. But the lack of spectral data across telluric absorption bands in the wavelength region 2.5 to 2.9 micrometres--where the OH stretching vibration and the H2O bending overtone are found--has precluded definitive identifications. In addition, water vapour around Ceres has recently been reported, possibly originating from localized sources. Here we report spectra of Ceres from 0.4 to 5 micrometres acquired at distances from ~82,000 to 4,300 kilometres from the surface. Our measurements indicate widespread ammoniated phyllosilicates across the surface, but no detectable water ice. Ammonia, accreted either as organic matter or as ice, may have reacted with phyllosilicates on Ceres during differentiation. This suggests that material from the outer Solar System was incorporated into Ceres, either during its formation at great heliocentric distance or by incorporation of material transported into the main asteroid belt.

  10. Biosignatures Preservation Potential and Habitability in Phyllosilicates vs. Iron-rich Environments

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; Stoker, C. R.; McKay, C. P.; Science Team

    2008-12-01

    Phyllosilicates have been identified on the surface of Mars by the OMEGA-Mars/Express [e.g., 1], the Mars Reconnaissance Orbiter (MRO) instruments, i.e., HiRISE and CRISM, as well as inferred from rover observations in Gusev Crater [2]). A better understanding of the preservation potential and habitability in phyllosilicates and hematite-rich materials, achieved by studying analog sites, will therefore provide critical information in support of next decade missions landing site selection e.g., 2009 Mars Science Laboratory (MSL), the ESA Pasteur ExoMars. We present geochemical (d13C-org, d13N-tot, CN ratios) and microbiological proxies i.e., Adenosin-Triphosphate (ATP-based) and Limulus-Amebocite-Lysate (LAL-based biomass) from a suite of phyllosilicate and iron-rich environmental samples e.g., Rio Tinto (Spain), Death Valley (CA, USA), Atacama Desert (Chile), and the California coast. Phyllosilicates-rich zones (47-74wt.%) from the Rio Tinto (RT) region can preserve up to 10-time higher amount of organics (C-org = 0.23 wt.%) than the embedding hematite/goethite-rich (34-89 wt.%) rocks i.e., C-org: ~0.05 wt.% [4]. It is possible that under low pH and highly oxidizing conditions [e.g., 3] surface-derived organics are rapidly oxidized within the shallow hematite/goethite-rich materials, but preserved in phyllosilicates (smectites/illite) where conditions are more conducive [4]. ATP-based biomass was detected in some oxidized-rock samples where roots materials were present (750-1245 RLUs). Geochemical and microbiological analyses are underway to confirm the preservation/ habitability trends observed in the Rio Tinto near surface. Preliminary results suggest that oxidized, goethite-rich, sandstone (Purisima formation, CA) have higher ATP- and LAL-based (Gram negative) biomass contents i.e., 2.0 107 cell/g (35.05 EU/mL) and 3891 RLUs, than the overlying clays units i.e., 1.34 107 cell/g (22.0EU/mL) and 1143 RLUs. REFERENCES: [1] Bibring et al., 2006, Science 312

  11. Excavation of Stratified Phyllosilicate-Bearing Rocks in the Northern Plains of Mars

    NASA Astrophysics Data System (ADS)

    Gross, C.; Carter, J.; Tornabene, L. L.; Sowe, M.; Bishop, J. L.

    2014-12-01

    The Noachian southern highlands of Mars bear old crustal material which appears mostly unaltered (Bandfield, 2002; Bibring et al., 2005; Christensen et al., 2005) and contains phyllosilicate-rich material. Phyllosilicates are of particular interest, as they require the presence of liquid water over long terms and may represent habitable environments. Most phyllosilicates formed early in Mars' history during the Noachian period (Bibring et al., 2006). However, a set of Hesperian-aged impact craters, Toro (Marzo et al., 2010) and Majuro (Mangold et al., 2012) bear evidence for impact-induced hydrothermal activity in the southern highlands. Phyllosilicate outcrops in the northern plains are exclusively found in and around impact craters. This could lead to the conclusion that they might form excavation products of preexisting, buried deposits, exposed by impacting and erosion (Carter et al. 2010; Bibring et al. 2006; Murchie et al. 2009). Nevertheless, when investigating alteration associated with impact craters, pre-, syn- and post-impact scenarios have to be considered (Osinski et al., 2013; Tornabene et al., 2013). We revisited a set of impact sites described by Carter et al. (2010) for further investigation and to test the theory of impact excavation of old preexisting strata versus impact-induced hydrothermal activity. This can be achieved as coverage of high resolution data has drastically increased during the time of that study. We here report the presence of uplifted, stratified, phyllosilicate-rich material in an impact crater, located in the northern plains of Mars, close to the dichotomy boundary. References: Bandfield (2002) JGR, 107, E6, 5042. Bibring et al. (2005) Science, 307, 1576-1581. Christensen et al. (2005) Nature, 436, 504-509. Bibring et al. (2006) Science, 312, 400-404. Marzo et al. (2010) Icarus, 208, 667-683. Mangold et al. (2012) PSS, 72, 18-30. Carter et al. (2010) Science, 328, 1682-1686. Murchie et al. (2009) JGR, 114, E00D06. Osinski et

  12. Identification of Phyllosilicates in Mudstone Samples Using Water Releases Detected by the Sample Analysis at Mars (SAM) Instrument in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Hogancamp, J. V. (Clark); Ming, D. W.; McAdam, A. C.; Archer, P. D.; Morris, R. V.; Bristow, T. F.; Rampe, E. B.; Mahaffy, P. R.; Gellert, R.

    2017-01-01

    The Sample Analysis at Mars (SAM) instrument on board the Curiosity Rover has detected high temperature water releases from mud-stones in the areas of Yellowknife Bay, Pahrump Hills, Naukluft Plateau, and Murray Buttes in Gale crater. Dehydroxylation of phyllosilicates may have caused the high temperature water releases observed in these samples. Because each type of phyllosilicate undergoes dehydroxylation at distinct temperatures, these water releases can be used to help constrain the type of phyllosilicate present in each sample.

  13. Characterization of phyllosilicates observed in the central Mawrth Vallis region, Mars, their potential formational processes, and implications for past climate

    McKeown, N.K.; Bishop, J.L.; Noe Dobrea, E.Z.; Ehlmann, B.L.; Parente, M.; Mustard, J.F.; Murchie, S.L.; Swayze, G.A.; Bibring, J.-P.; Silver, E.A.

    2009-01-01

    Mawrth Vallis contains one of the largest exposures of phyllosilicates on Mars. Nontronite, montmorillonite, kaolinite, and hydrated silica have been identified throughout the region using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). In addition, saponite has been identified in one observation within a crater. These individual minerals are identified and distinguished by features at 1.38-1.42, ???1.91, and 2.17-2.41 ??m. There are two main phyllosilicate units in the Mawrth Vallis region. The lowermost unit is nontronite bearing, unconformably overlain by an Al-phyllosilicate unit containing montmorillonite plus hydrated silica, with a thin layer of kaolinite plus hydrated silica at the top of the unit. These two units are draped by a spectrally unremarkable capping unit. Smectites generally form in neutral to alkaline environments, while kaolinite and hydrated silica typically form in slightly acidic conditions; thus, the observed phyllosilicates may reflect a change in aqueous chemistry. Spectra retrieved near the boundary between the nontronite and Al-phyllosilicate units exhibit a strong positive slope from 1 to 2 ??m, likely from a ferrous component within the rock. This ferrous component indicates either rapid deposition in an oxidizing environment or reducing conditions. Formation of each of the phyllosilicate minerals identified requires liquid water, thus indicating a regional wet period in the Noachian when these units formed. The two main phyllosilicate units may be extensive layers of altered volcanic ash. Other potential formational processes include sediment deposition into a marine or lacustrine basin or pedogenesis. Copyright 2009 by the American Geophysical Union.

  14. Contemporaneous deposition of phyllosilicates and sulfates: Using Australian acidic saline lake deposits to describe geochemical variability on Mars

    Baldridge, A.M.; Hook, S.J.; Crowley, J.K.; Marion, G.M.; Kargel, J.S.; Michalski, J.L.; Thomson, B.J.; de Souza, Filho C.R.; Bridges, N.T.; Brown, A.J.

    2009-01-01

    Studies of the origin of the Martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked, global-scale change in the Mars environment from circum-neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to Hesperian. However, terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation.Western Australian acidic playa lakes have large pH differences separated vertically and laterally by only a few tens of meters, demonstrating how highly variable chemistries can coexist over short distances in natural environments. We suggest diverse and variable Martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the Australian sites are analogs for regions where phyllosilicates and sulfates coexist on Mars. In these systems, Fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater, whereas aluminous phyllosilicates and sulfates represent near-surface evaporitic facies formed from more acidic brines. Copyright 2009 by the American Geophysical Union.

  15. Molecular Simulation of Cesium Adsorption at the Basal Surface of Phyllosilicate Minerals

    SciT

    Kerisit, Sebastien N.; Okumura, Masahiko; Rosso, Kevin M.

    2016-08-16

    A better understanding of the thermodynamics of radioactive cesium uptake at the surfaces of phyllosilicate minerals is needed to understand mechanisms of its selective adsorption and help guide the development of practical and inexpensive decontamination techniques. In this work, molecular dynamics simulations were carried out to determine the thermodynamics of adsorption of Cs + at the basal surface of six 2:1 phyllosilicate minerals, namely pyrophyllite, illite, muscovite, phlogopite, celadonite, and margarite. These minerals were selected to isolate the effects of the magnitude of the permanent layer charge (≤ 2), its location (tetrahedral versus octahedral sheet), and the structure of themore » octahedral sheet (dioctahedral versus trioctahedral). Good agreement was obtained with experiment in terms of the hydration free energy of Cs + and the structure and thermodynamics of Cs + adsorption at the muscovite basal surface, for which published data were available for comparison. With the exception of pyrophyllite, which did not exhibit an inner-sphere free energy minimum, all phyllosilicate minerals showed similar behavior with respect to Cs + adsorption; notably, Cs + adsorption was predominantly inner-sphere whereas outer-sphere adsorption was very weak with the simulations predicting the formation of an extended outer-sphere complex. For a given location of the layer charge, the free energy of adsorption as an inner-sphere complex was found to vary linearly with the magnitude of the layer charge. For a given location and magnitude of the layer charge, adsorption at phlogopite (trioctahedral sheet structure) was much less favorable than at muscovite (dioctahedral sheet structure) due to the electrostatic repulsion between the adsorbed Cs + and the hydrogen atom of the hydroxyl group directly below the six-membered siloxane ring cavity. For a given magnitude of the layer charge and structure of the octahedral sheet, adsorption at celadonite (layer charge

  16. Laboratory Far-infrared Spectroscopy Of Terrestrial Phyllosilicates To Support Analysis Of Cosmic Dust Spectra.

    NASA Astrophysics Data System (ADS)

    Yesiltas, Mehmet; Brusentsova, T.; Peale, R.; Maukonen, D.; Figueiredo, P.; Harlow, G. H.; Ebel, D. S.; Nissinboim, A.; Sherman, K.; Lisse, C. M.

    2012-01-01

    Poster Abstract: 219th AAS Meeting M. Yesiltas1, T. Brusentsova1, R. E. Peale1, D. Maukonen1, P. Figueiredo1, G. E. Harlow2, D. S. Ebel2, A. Nissinboim2, K. Sherman2, and C. M. Lisse3 Remote spectral detection of hydrated minerals is of general interest in the solar system and dusty circumstellar disks. This paper presents spectroscopy of terrestrial phyllosilicate minerals in the wavelength range 15 - 250 µm to support interpretation of returned data from far-IR space-missions such as the Herschel Space Observatory. The far-IR spectral region beyond 15 micron wavelength is especially diagnostic of mineral composition and crystal structure. Relatively little far-IR spectral data exists in the literature on suitably-characterized naturally-occurring phyllosilicate minerals in the wavelength range 60-210 microns corresponding to the PACS instrument of Herschel Space Observatory. Extending the database of laboratory far-IR spectra of terrestrial mineral analogs is therefore desirable and timely. Seventeen phyllosilicate minerals expected in various astronomical environments were sampled from the American Museum of Natural History for diversity and astrophysical relevancy, based on their identification in Stardust, in stratospheric IDP samples, or in meteorites. These include serpentines (Antigorite and Chrysotile), smectites (Talc, Pyrophyllite, Vermiculite, Montmorillonite, Beidellite, Saponite, Nontronite and Hectorite), chlorites (Clinochlore), micas (Muscovite, Paragonite, Margarite, Clintonite, Biotite and Illite), and kaolinites (Dickite, Nacrite, Kaolinite, Halloysite, Attapulgite and Sepiolite). Spectra of micron-sized powder suspensions in polyethelyne pellets reveal prominent and characteristic far-IR features, which differ significantly in some cases from already published spectra, where available. Acknowledgements : This research was supported by NASA-JPL Contract # 1327221. 1Department of Physics, University of Central Florida, Orlando FL 32816 USA2

  17. Physical Diversity of Phyllosilicate Deposits at the MSL Candidate Landing Sites

    NASA Astrophysics Data System (ADS)

    Fergason, R. L.

    2008-12-01

    The identification of phyllosilicates on Mars implies aqueous activity at the time of their formation and is important for understanding the history of Martian water and the past habitability of Mars. In addition, a significant fraction of the global water budget of Mars may be locked into clay mineral deposits within the Martian crust. As a result, six out of seven final landing sites being considered for the Mars Science Laboratory are sites where phyllosilicates have been identified in CRISM and OMEGA data. The physical characteristics of these materials, as identified using thermal inertia data, are an important component for understanding the geologic history of these deposits. Thermal inertia values provide information regarding effective particle size and help to constrain the possible presence of duricrust, rocks, and exposed bedrock at these locations. These identified physical characteristics suggest the degree of resistivity to erosion, which has implications for the post-emplacement modification of these deposits. At the aforementioned six locations (Nili Fossae Trough, Holden Crater, Mawrth Vallis, Miyamoto crater, southern Meridiani Planum, and Gale crater) the physical properties were quantified using THEMIS-derived thermal inertia data to characterize the physical properties at each site and identify the presence or absence of physical diversity among these materials. I identified a wide range of surface properties at these locations ranging from indurated surfaces intermixed with unconsolidated aeolian material (thermal inertia of 150-460 J m-2 K-1 s- 1/2) at Mawrth Vallis, to exposures of in-place bedrock and the presence of rocky material (thermal inertia exceeding 800 J m-2 K-1 s-1/2) in Gale crater. In addition, the surface texture and morphologic features observed in high-resolution visible images (such as narrow-angle MOC, HiRISE, and CTX) are dissimilar across these phyllosilicate exposures, and confirm the interpretation of thermal inertia

  18. Mineralogy of dark asteroids: Detection of phyllosilicate features in the mid-infrared

    NASA Astrophysics Data System (ADS)

    McAdam, Margaret; Sunshine , Jessica Sunshine M.; Kelley, Michael S.

    2014-11-01

    Dark asteroids (C- and related types) have been shown to have phyllosilicates on their surfaces by the presence of the 0.7-µm charge transfer band in the visible/near-infrared (VIS/NIR) spectral region (e.g. [1], [2]). Observations of asteroids in the 2.5-5-µm have also indicated the presence of water [3, 4] and phyllosilicates [5, 6]. Phyllosilicates also have spectral features in the 8-30-µm [7]. The results of a coordinated spectral-mineralogical study of aqueously altered meteorites [8] can be used to both remotely identify the presence of aqueous alteration and determine the degree of alteration on asteroids. Two main regions have strong features related to the mineralogy and degree of alteration: the 10-13-µm and the 16-25-µm region. Alteration features change continuously in these regions between less 60%) and highly 90%) altered meteorites. These features have been identified in the spectra of some dark asteroids [8, 9, 10]. Additionally, no trends are found between 0.7-µm charge transfer band and degree of alteration. While all meteorites with a 0.7-µm band have phyllosilicates, the absence of a 0.7-µm band is not indicative of the absence of alteration. Altered meteorites always exhibit MIR features that are directly related to their degree of alteration whether or not they have a 0.7-µm band. Here, we present preliminary results of a survey of archived Spitzer Space Telescope data of asteroids in the 10-13-µm region and the 16-25-µm region (where data is available) including comparisons to published VIS/NIR spectra of the same dark asteroids without VIS/NIR features. Possible effects in comparing laboratory measurements of meteorite powders under ambient conditions to telescopic spectra of asteroid regoliths are considered. [1] Vilas and Gaffey, (1989) Nature, 246, 790-792. [2] Barucci et al (1998) Icarus, 132, 388-396. [3] Campins et al., (2010), Nature Letters, 464, 1320-1321. [4] Rivkin & Emery (2010) Nature Letters, 464, 1322-1323. [5

  19. Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra.

    PubMed

    Vilas, F; Gaffey, M J

    1989-11-10

    Absorption features having depths up to 5% are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

  20. Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Gaffey, Michael J.

    1989-01-01

    Absorption features having depths up to 5 percent are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

  1. Adsorption of nucleotides onto ferromagnesian phyllosilicates: Significance for the origin of life

    NASA Astrophysics Data System (ADS)

    Pedreira-Segade, Ulysse; Feuillie, Cécile; Pelletier, Manuel; Michot, Laurent J.; Daniel, Isabelle

    2016-03-01

    The concentration of prebiotic organic building blocks may have promoted the formation of biopolymers in the environment of the early Earth. We therefore studied the adsorption of RNA monomers AMP, GMP, CMP, and UMP, and DNA monomers dGMP, dCMP, and TMP, on minerals that were abundant in the early Earth environment as the result of aqueous or hydrothermal alteration of the primitive oceanic crust. We focused our study on swelling clays, i.e. nontronite and montmorillonite, and non-swelling phyllosilicates, i.e. pyrophyllite, chlorite, lizardite and chrysotile suspended in an aqueous saline solution analog to seawater. In this reference study, adsorption experiments were carried out under standard conditions of pressure and temperature and controlled pH. Under such conditions, this work is also relevant to the preservation of nucleic acids in Fe-Mg-rich terrestrial and Martian soils. We compared the adsorption of the different monomers on individual minerals, as well as the adsorption of single monomers on the whole suite of minerals. We found that DNA monomers adsorb much more strongly than RNA monomers, and that any monomer containing the G nucleobase adsorbed more strongly than one containing the C nucleobase. At high surface loadings (greater than about 1 mM monomer in aqueous solution) we also found a dramatic increase in the slope of adsorption isotherm on the swelling clays, leading to large increases in the amounts adsorbed. Data were processed in order to understand the adsorption mechanism of nucleotides onto mineral surfaces. We infer that all nucleotides behave as homologous molecules in regard to their adsorption onto the studied mineral surfaces. At low to moderate surface loadings, their adsorption is best explained by a single mechanism common to the suite of minerals of the present study. At pH 7, adsorption certainly proceeds by ligand exchange between the phosphate group and the hydroxyls of the broken edges of phyllosilicates leading to the

  2. Spectral analysis of Deccan intrabasaltic bole beds: Implications for the formation and alteration of phyllosilicates on Mars

    NASA Astrophysics Data System (ADS)

    Craig, Patricia; Chevrier, Vincent; Sayyed, M. R. G.; Islam, R.

    2017-01-01

    To fully understand phyllosilicates on Mars, it is beneficial to study analog deposits on Earth. One attractive candidate for martian phyllosilicates is the intrabasaltic bole beds (palaeosols) from the Deccan Volcanic Province of India. Eleven samples from the upper-layer red Deccan bole beds and underlying yellow and green Deccan bole beds were analyzed by X-ray diffraction (XRD), near-infrared (1.0-2.5 μm) and mid-infrared (5-15 μm) reflectance spectroscopy. Analysis of the bole beds indicated that the red boles are composed of a mixture of montmorillonite and hematite, yellow boles contain vermiculite and minor montmorillonite and green boles are composed mainly of nontronite (smectite) and celadonite (mica). While the bole beds are all chemically similar to each other and to the underlying basalt from which they were weathered, they are mineralogically different. This suggests transformation from one mineral to the next without ion transfer or loss which could be indicative of a limited-water environment. In fact, celadonite can transform into smectites (such as montmorillonite), often with vermiculite as an intermediate step. This not only explains the stratigraphy and mineralogy of the Deccan bole beds but may also explain the layered phyllosilicates identified in various, global locations on Mars. The transition observed in the Deccan bole beds suggests an evolution of the alteration process from deuteric alteration to low-temperature weathering, likely due to changes in temperature, in a closed system (no significant ion transfer) as evidenced by the minerals' similar chemistry. Thus, the Deccan bole beds are a good analog for the phyllosilicates layers on Mars and by studying the chemistry, mineralogy and spectral properties of the Deccan bole beds, we can link their formation and alteration processes to those of martian phyllosilicates. This will provide a clearer understanding of the environmental conditions on Mars at the time of the phyllosilicates

  3. Phyllosilicate diversity and past aqueous activity revealed at Mawrth Vallis, Mars

    Bishop, J.L.; Dobrea, E.Z.N.; McKeown, N.K.; Parente, M.; Ehlmann, B.L.; Michalski, J.R.; Milliken, R.E.; Poulet, F.; Swayze, G.A.; Mustard, J.F.; Murchie, S.L.; Bibring, J.-P.

    2008-01-01

    Observations by the Mars Reconnaissance Orbiter/Compact Reconnaissance Imaging Spectrometer for Mars in the Mawrth Vallis region show several phyllosilicate species, indicating a wide range of past aqueous activity. Iron/magnesium (Fe/Mg)-smectite is observed in light-toned outcrops that probably formed via aqueous alteration of basalt of the ancient cratered terrain. This unit is overlain by rocks rich in hydrated silica, montmorillonite, and kaolinite that may have formed via subsequent leaching of Fe and Mg through extended aqueous events or a change in aqueous chemistry. A spectral feature attributed to an Fe2+ phase is present in many locations in the Mawrth Vallis region at the transition from Fe/Mg-smectite to aluminum/silicon (Al/Si)-rich units. Fe2+-bearing materials in terrestrial sediments are typically associated with microorganisms or changes in pH or cations and could be explained here by hydrothermal activity. The stratigraphy of Fe/Mg-smectite overlain by a ferrous phase, hydrated silica, and then Al-phyllosilicates implies a complex aqueous history.

  4. Interaction of divalent cations with basal planes and edge surfaces of phyllosilicate minerals: muscovite and talc.

    PubMed

    Yan, Lujie; Masliyah, Jacob H; Xu, Zhenghe

    2013-08-15

    Smooth basal plane and edge surfaces of two platy phyllosilicate minerals (muscovite and talc) were prepared successfully to allow accurate colloidal force measurement using an atomic force microscope (AFM), which allowed us to probe independently interactions of divalent cations with phyllosilicate basal planes and edge surfaces. The Stern potential of basal planes and edge surfaces was obtained by fitting the measured force profiles with the classical DLVO theory. The fitted Stern potential of the muscovite basal plane became less negative with increasing Ca(2+) or Mg(2+) concentration but did not reverse its sign even at Ca(2+) or Mg(2+) concentrations up to 5 mM. In contrast, the Stern potential of the muscovite edge surface reversed at Ca(2+) or Mg(2+) concentrations as low as 0.1 mM. The Stern potential of the talc basal plane became less negative with 0.1 mM Ca(2+) addition and nearly zero with 1 mM Ca(2+) addition. The Stern potential of talc edge surface became reversed with 0.1 mM Ca(2+) or 1 mM Mg(2+) addition, showing not only a different binding mechanism of talc basal planes and edge surfaces with Ca(2+) and Mg(2+), but also different binding mechanism between Ca(2+) and Mg(2+) ions with basal planes and edge surfaces. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Aminopropyl-modified magnesium-phyllosilicates: layered solids with tailored interlayer access and reactivity.

    PubMed

    Ferreira, Ricardo B; da Silva, César R; Pastore, Heloise O

    2008-12-16

    Despite its wide application, the synthesis of aminopropyl-modified magnesium-phyllosilicates was known only in the case where every silicon atom bore an organic pending group. This paper shows the preparation of aminopropyl-modified talc where tailored amounts of silicon atoms are bound to an aminopropyl group. The decrease in the concentration of the organoamino group leaves a proportional concentration of interlayer SiOH groups that can be used to react with other silylation agents. The amino group reacts with CO2, forming a carbamate functionality; it seems that the presence of this group avoids delamination in water as performed for the parent compound. Bearing in mind that the aminopropyl group can be changed by other groups, the present synthesis strategy demonstrates ways to produce solids with controlled surface properties with interlayer amino and SiOH groups in variable concentrations, allowing formation of several other interlayer functionalities.

  6. Contrasting frictional behaviour of fault gouges containing Mg-rich phyllosilicates

    NASA Astrophysics Data System (ADS)

    Sanchez Roa, C.; Faulkner, D.; Jimenez Millan, J.; Nieto, F.

    2015-12-01

    The clay mineralogy of fault gouges has important implications on frictional properties and stability of fault planes. We studied the specific case of the Galera fault zone where fault gouges containing Mg-rich phyllosilicates appear as hydrothermal deposits related to high salinity fluids enriched in Mg2+. These deposits are dominated by sepiolite and palygorskite, both fibrous clay minerals with similar composition to Mg-smectite. The frictional strengths of sepiolite and palygorskite have not yet been determined, however, as they are part of the clay mineral group, it has been assumed that their frictional behaviour would be in line with platy clay minerals. We performed frictional sliding experiments on powdered pure standards and fault rocks in order to establish the frictional behaviour of sepiolite and palygorskite using a triaxial deformation apparatus with a servo-controlled axial loading system and fluid pressure pump. Friction coefficients for palygorskite and sepiolite as monomineralic samples were found to be 0.65 to 0.7 for dry experiments, and 0.45 to 0.5 for water-saturated experiments. Although these fibrous minerals are part of the phyllosilicates group, they show higher friction coefficients and their mechanical behaviour is less stable than platy clay minerals. This difference is a consequence of their stronger structural framework and the discontinuity of water layers. Our results present a contrast in mechanical behaviour between Mg-rich fibrous and platy clay minerals in fault gouges, where smectite is known to considerably reduce friction coefficients and to increase the stability of the fault plane leading to creeping processes. Transformations between saponite and sepiolite have been previously observed and could modify the deformation regime of a fault zone. Constraining the stability conditions and possible mineral reactions or transformations in fault gouges could help us understand the general role of clay minerals in fault stability.

  7. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on Mars from phyllosilicate mineral assemblages

    Ehlmann, Bethany L.; Mustard, John F; Clark, Roger N.; Swayze, Gregg A.; Murchie, Scott L.

    2011-01-01

    The enhanced spatial and spectral resolution provided by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) has led to the discovery of numerous hydrated silicate minerals on Mars, particularly in the ancient, cratered crust comprising the southern highlands. Phases recently identified using visible/near-infrared spectra include: smectite, chlorite, prehnite, high-charge phyllosilicates (illite or muscovite), the zeolite analcime, opaline silica, and serpentine. Some mineral assemblages represent the products of aqueous alteration at elevated temperatures. Geologic occurrences of these mineral assemblages are described using examples from west of the Isidis basin near the Nili Fossae and with reference to differences in implied temperature, fluid composition, and starting materials during alteration. The alteration minerals are not distributed homogeneously. Rather, certain craters host distinctive alteration assemblages: (1) prehnite-chlorite-silica, (2) analcime-silica-Fe,Mg-smectite-chlorite, (3) chlorite-illite (muscovite), and (4) serpentine, which furthermore has been found in bedrock units. These assemblages contrast with the prevalence of solely Fe,Mg-smectites in most phyllosilicate-bearing terrains on Mars, and they represent materials altered at depth then exposed by cratering. Of the minerals found to date, prehnite provides the clearest evidence for subsurface, hydrothermal/metamorphic alteration, as it forms only under highly restricted conditions (T = 200–400ºC). Multiple mechanisms exist for forming the other individual minerals; however, the most likely formation mechanisms for the characteristic mineralogic assemblages observed are, for (1) and (2), low-grade metamorphism or hydrothermal (<400ºC) circulation of fluids in basalt; for (3), transformation of trioctahedral smectites to chlorite and dioctahedral smectites to illite during diagenesis; and for (4), low-grade metamorphism or

  8. Origin and evolution of phyllosilicate deformation bands in the poorly lithified sandstones of the Rio do Peixe Basin, NE Brazil

    NASA Astrophysics Data System (ADS)

    Nogueira, Francisco; Nicchio, Matheus; Balsamo, Fabrizio; Bezerra, Francisco; Souza, Jorge; Carvalho, Bruno; Storti, Fabrizio

    2017-04-01

    In this work we describe the genetic processes and the microstructural evolution of phylossilicate deformation bands developed in poorly lithified, high porosity sandstones of the Rio do Peixe Basin, Northeast Brazil. The studied deformation bands occur in damage zones of NE-SW and NW-SE transtensional faults that exhibit well developed anastomosed clusters, with a thickness varying from tens of centimeters to 1 meter. The Host rocks are arkosic to lithic arkosic coarse sandstones to fine conglomerate and with less than 1% of clay content in the matrix. Based on (i) field observations, (ii) clay amount in deformation band cores and (iii) clay mineral arrangements in deformation bands cores, we identified two types of phyllosilicate deformation bands: (1) clay smearing deformation bands and (2) phyllosilicate deformation bands formed by clay authigenesis. The former occur only in fault zones that cut across clay-rich layers and are characterized by 45-50% of clay content. Single element chemical analysis indicates that the composition of clay minerals in clay smearing deformation bands is similar to that of clay-rich layers in the host rocks. The dominant deformation mechanism is particulate flow, which produces preferential alignments of grains and clay minerals. Only subordinate cataclasis occurs. Based on microstructural fabrics, three evolutionary stages can be identified for phyllosilicate deformation bands formed by clay authigenesis. The first one is characterized by preferentially cataclasis and weathering of feldspars. Clay concentration is relatively low, reaching 15-20%, with preferential concentration where crushed feldspar abundance is higher. The second stage is characterized by clay migration within deformation bands, to form continuous films with more than 20-25% of clay concentration. In the last stage clay mineral fabric re-organization occurs, forming well a developed S-C foliation. Clay concentration exceeds 35%. Single element chemical analysis

  9. Crystal structure characteristics, dielectric loss, and vibrational spectra of Zn-rich non-stoichiometric Ba[(Zn1/3Nb2/3)1-x Zn x ]O3 ceramics

    NASA Astrophysics Data System (ADS)

    Li, Jianzhu; Xing, Chao; Qiao, Hengyang; Chen, Huiling; Yang, Jun; Dong, Helei; Shi, Feng

    2017-07-01

    Zn-Rich non-stoichiometric Ba(Zn1/3Nb2/3)1-x Zn x O3 (BZNZ) (x  =  0.01, 0.02, 0.03, 0.04) ceramics were prepared by the solid-state reaction method at 1500 °C for 2 h. The crystal structures and morphologies were analyzed by x-ray diffraction (XRD) and scanning electron microscopy. The vibration modes were obtained by Raman scattering spectroscopy and Fourier transform far-infrared (FTIR) reflectance spectroscopy. Rietveld refinement was performed for the XRD data. The relationship between crystal structures, dielectric properties, and phonon modes was analyzed in detail. XRD results show that the main phase is Ba(Zn1/3Nb2/3)O3. The Raman results displayed that the ordering structure of BZNZ transformed from 1:2 to 1:1 when x changed from 0.02 to 0.04, and the dielectric losses have a positive correlation with the full width at half maximum values of the A 1g(O) and E g(O) modes. The FTIR spectra were analyzed by the Kramers-Krönig method to obtain the real parts (ɛ‧) and the imaginary parts (ɛ″) of the dielectric constant. When x  =  0.02, the sample possesses uniform grains with clear boundaries and the lowest dielectric loss value (tanδ  =  5.5  ×  10‒4) due to the largest packing fraction.

  10. Mineralogy and stratigraphy of phyllosilicate-bearing and dark mantling units in the greater Mawrth Vallis/west Arabia Terra area: Constraints on geological origin

    Noe Dobrea, E.Z.; Bishop, J.L.; McKeown, N.K.; Fu, R.; Rossi, C.M.; Michalski, J.R.; Heinlein, C.; Hanus, V.; Poulet, F.; Mustard, R.J.F.; Murchie, S.; McEwen, A.S.; Swayze, G.; Bibring, J.-P.; Malaret, E.; Hash, C.

    2010-01-01

    Analyses of MRO/CRISM images of the greater Mawrth Vallis region of Mars affirm the presence of two primary phyllosilicate assemblages throughout a region ∼1000 × 1000 km. These two units consist of an Fe/Mg-phyllosilicate assemblage overlain by an Al-phyllosilicate and hydrated silica assemblage. The lower unit contains Fe/Mg-smectites, sometimes combined with one or more of these other Fe/Mg-phyllosilicates: serpentine, chlorite, biotite, and/or vermiculite. It is more than 100 m thick and finely layered at meter scales. The upper unit includes Al-smectite, kaolin group minerals, and hydrated silica. It is tens of meters thick and finely layered as well. A common phyllosilicate stratigraphy and morphology is observed throughout the greater region wherever erosional windows are present. This suggests that the geologic processes forming these units must have occurred on at least a regional scale. Sinuous ridges (interpreted to be inverted channels) and narrow channels cut into the upper clay-bearing unit suggesting that aqueous processes were prevalent after, and possibly during, the deposition of the layered units. We propose that layered units may have been deposited at Mawrth Vallis and then subsequently altered to form the hydrated units. The Fe/Mg-phyllosilicate assemblage is consistent with hydrothermal alteration or pedogenesis of mafic to ultramafic rocks. The Al-phyllosilicate/hydrated silica unit may have formed through alteration of felsic material or via leaching of basaltic material through pedogenic alteration or a mildly acidic environment. These phyllosilicate-bearing units are overlain by a darker, relatively unaltered, and indurated material that has probably experienced a complex geological history.

  11. Toward an understanding of phyllosilicate mineralogy in the outer main asteroid belt

    NASA Astrophysics Data System (ADS)

    Takir, Driss; Emery, Joshua P.; McSween, Harry Y.

    2015-09-01

    Proposed mineralogical linkages between CM/CI carbonaceous chondrites and outer Main Belt asteroids remain uncertain due to a dearth of diagnostic absorptions in visible and near-infrared (∼0.4-2.5 μm) spectra of the two sets of objects. Absorptions near 3 μm in both sets hold promise for illuminating the potential linkages. Spectral comparisons of meteorites and asteroids have been challenging because meteorite spectra have usually been acquired in ambient terrestrial environments, and hence were contaminated by atmospheric water. In this study, we compare near-infrared spectra of chondrites measured in the laboratory under asteroid-like conditions (Takir, D. et al. [2013]. Meteorit. Planet. Sci. 48, 1618-1637) and spectra of asteroids measured with the long-wavelength cross-dispersed (LXD: 1.9-4.2-μm) mode of the SpeX spectrograph/imager at the NASA Infrared Telescope Facility (IRTF) (Takir, D., Emery, J.P. [2012]. Icarus 219, 641-654). Using the 3-μm band shape, we find that spectral Group 2 CM and CI (Ivuna) chondrites are possible meteorite analogs for asteroids with the sharp 3-μm features, which are predominately located in the 2.5 < a < 3.3 AU region. Spectral Group 2 CM chondrites contain phyllosilicate phases intermediate between endmembers Fe-serpentine and Mg-serpentine, with a petrological subtype ranging from 2.2 to 2.1 (Takir, D. et al. [2013]. Meteorit. Planet. Sci. 48, 1618-1637). No meteorite match was found for asteroids showing a rounded 3-μm feature, which tend to be located farther from the Sun (3.0 < a < 4.0 AU), or for asteroids with distinctive spectra like 1 Ceres or 52 Europa. The study of the 3-μm band in meteorites and asteroids has implications for the understanding of phyllosilicate mineralogy and its distribution in the outer Main Belt region.

  12. The Effect of Authigenic Phyllosilicate Growth on the Mechanical Behaviour of Upper Crustal Faults

    NASA Astrophysics Data System (ADS)

    Evans, S.; Holdsworth, R.; Imber, J.; Marco, S.; Weinberger, R.; De Paola, N.

    2014-12-01

    Deformation at shallow crustal depths is dominated by brittle processes, but it is increasingly recognised that diffusive mass transfer (DMT) processes and "ductile" folding also play a significant role in fault zone development. We present data from exhumed sections (<5 km depth) of the southern Dead Sea Fault System, Israel, an active continental transform fault that has accumulated 105 km of sinistral displacement since the Miocene. The faults juxtapose various wall rock lithologies (crystalline basement, carbonate and clastic cover), but the studied sections all have phyllosilicate-rich fault cores. Damage zones show a range of deformation mechanisms including pulverisation, pressure-solution and cataclasis. Our results show that fault cores comprise three distinct types of fault gouge (alongside coarser-grained cataclasite): cataclastic gouge that is mineralogically similar to wall rock compositions; authigenic gouge that is dominated by Mg-rich smectite not present in adjacent formations; and mechanically entrained, folded shale gouge that is almost identical in mineralogy to a local shale protolith. Microstructural observations suggest authigenic gouge is the result of DMT processes, following an earlier phase of gouge formation through microfracturing and cataclasis. The low abundance of carbonate within fault cores suggests its dissolution is a contributing factor in authigenic smectite precipitation. Such mineralogical transformations may lead to significant changes in the frictional properties of fault zones, from materials of relatively high frictional strength (quartz, feldspars, dolomite, where μ = 0.6 - 0.85) to those with much lower frictional strengths, such as smectite (where μ can be as low as 0.15). We demonstrate how the physical properties of faults may evolve over time when conditions allow precipitation of weak-phases in addition to brittle deformation, which may facilitate ingress of fluid into fault cores and enhance phyllosilicate

  13. Chemical models for martian weathering profiles: Insights into formation of layered phyllosilicate and sulfate deposits

    NASA Astrophysics Data System (ADS)

    Zolotov, Mikhail Yu.; Mironenko, Mikhail V.

    2016-09-01

    Numerical chemical models for water-basalt interaction have been used to constrain the formation of stratified mineralogical sequences of Noachian clay-bearing rocks exposed in the Mawrth Vallis region and in other places on cratered martian highlands. The numerical approaches are based on calculations of water-rock type chemical equilibria and models which include rates of mineral dissolution. Results show that the observed clay-bearing sequences could have formed through downward percolation and neutralization of acidic H2SO4-HCl solutions. A formation of weathering profiles by slightly acidic fluids equilibrated with current atmospheric CO2 requires large volumes of water and is inconsistent with observations. Weathering by solutions equilibrated with putative dense CO2 atmospheres leads to consumption of CO2 to abundant carbonates which are not observed in clay stratigraphies. Weathering by H2SO4-HCl solutions leads to formation of amorphous silica, Al-rich clays, ferric oxides/oxyhydroxides, and minor titanium oxide and alunite at the top of weathering profiles. Mg-Fe phyllosilicates, Ca sulfates, zeolites, and minor carbonates precipitate from neutral and alkaline solutions at depth. Acidic weathering causes leaching of Na, Mg, and Ca from upper layers and accumulation of Mg-Na-Ca sulfate-chloride solutions at depth. Neutral MgSO4 type solutions dominate in middle parts of weathering profiles and could occur in deeper layers owing to incomplete alteration of Ca minerals and a limited trapping of Ca to sulfates. Although salts are not abundant in the Noachian geological formations, the results suggest the formation of Noachian salty solutions and their accumulation at depth. A partial freezing and migration of alteration solutions could have separated sulfate-rich compositions from low-temperature chloride brines and contributed to the observed diversity of salt deposits. A Hesperian remobilization and release of subsurface MgSO4 type solutions into newly

  14. Dioctahedral Phyllosilicates Versus Zeolites and Carbonates Versus Zeolites Competitions as Constraints to Understanding Early Mars Alteration Conditions

    NASA Astrophysics Data System (ADS)

    Viennet, Jean-Christophe; Bultel, Benjamin; Riu, Lucie; Werner, Stephanie C.

    2017-11-01

    Widespread occurrence of Fe,Mg-phyllosilicates has been observed on Noachian Martian terrains. Therefore, the study of Fe,Mg-phyllosilicate formation, in order to characterize early Martian environmental conditions, is of particular interest to the Martian community. Previous studies have shown that the investigation of Fe,Mg-smectite formation alone helps to describe early Mars environmental conditions, but there are still large uncertainties in terms of pH range, oxic/anoxic conditions, etc. Interestingly, carbonates and/or zeolites have also been observed on Noachian surfaces in association with the Fe,Mg-phyllosilicates. Consequently, the present study focuses on the dioctahedral/trioctahedral phyllosilicate/carbonate/zeolite formation as a function of various CO2 contents (100% N2, 10% CO2/90% N2, and 100% CO2), from a combined approach including closed system laboratory experiments for 3 weeks at 120°C and geochemical simulations. The experimental results show that as the CO2 content decreases, the amount of dioctahedral clay minerals decreases in favor of trioctahedral minerals. Carbonates and dioctahedral clay minerals are formed during the experiments with CO2. When Ca-zeolites are formed, no carbonates and dioctahedral minerals are observed. Geochemical simulation aided in establishing pH as a key parameter in determining mineral formation patterns. Indeed, under acidic conditions dioctahedral clay minerals and carbonate minerals are formed, while trioctahedral clay minerals are formed in basic conditions with a neutral pH value of 5.98 at 120°C. Zeolites are favored from pH ≳ 7.2. The results obtained shed new light on the importance of dioctahedral clay minerals versus zeolites and carbonates versus zeolites competitions to better define the aqueous alteration processes throughout early Mars history.

  15. Improved cell disruption of Pichia pastoris utilizing aminopropyl magnesium phyllosilicate (AMP) clay.

    PubMed

    Kim, Sun-Il; Wu, Yuanzheng; Kim, Ka-Lyun; Kim, Geun-Joong; Shin, Hyun-Jae

    2013-06-01

    An efficient method for Pichia cell disruption that employs an aminopropyl magnesium phyllosilicate (AMP) clay-assisted glass beads mill is presented. AMP clay is functionalized nanocomposite resembling the talc parent structure Si8Mg6O20(OH)4 that has been proven to permeate the bacterial membrane and cause cell lysis. The recombinant capsid protein of cowpea chlorotic mottle virus (CCMV) expressed in Pichia pastoris GS115 was used as demonstration system for their ability of self-assembly into icosahedral virus-like particles (VLPs). The total protein concentration reached 4.24 mg/ml after 4 min treatment by glass beads mill combined with 0.2 % AMP clay, which was 11.2 % higher compared to glass beads mill only and the time was half shortened. The stability of purified CCMV VLPs illustrated AMP clay had no influence on virus assembly process. Considering the tiny amount added and simple approach of AMP clay, it could be a reliable method for yeast cell disruption.

  16. 2004 EW95: A Phyllosilicate-bearing Carbonaceous Asteroid in the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.; Brown, Michael E.; Schönebeck, Frederik

    2018-03-01

    Models of the Solar System’s dynamical evolution predict the dispersal of primitive planetesimals from their formative regions among the gas-giant planets due to the early phases of planetary migration. Consequently, carbonaceous objects were scattered both into the outer asteroid belt and out to the Kuiper Belt. These models predict that the Kuiper Belt should contain a small fraction of objects with carbonaceous surfaces, though to date, all reported visible reflectance spectra of small Kuiper Belt Objects (KBOs) are linear and featureless. We report the unusual reflectance spectrum of a small KBO, (120216) 2004 EW95, exhibiting a large drop in its near-UV reflectance and a broad shallow optical absorption feature centered at ∼700 nm, which is detected at greater than 4σ significance. These features, confirmed through multiple epochs of spectral photometry and spectroscopy, have respectively been associated with ferric oxides and phyllosilicates. The spectrum bears striking resemblance to those of some C-type asteroids, suggesting that 2004 EW95 may share a common origin with those objects. 2004 EW95 orbits the Sun in a stable mean motion resonance with Neptune, at relatively high eccentricity and inclination, suggesting it may have been emplaced there by some past dynamical instability. These results appear consistent with the aforementioned model predictions and are the first to show a reliably confirmed detection of silicate material on a small KBO.

  17. Dispersion of phyllosilicates in aqueous suspensions: role of the nature and amount of surfactant.

    PubMed

    Houta, Nadia; Lecomte-Nana, Gisèle-Laure; Tessier-Doyen, Nicolas; Peyratout, Claire

    2014-07-01

    The present work aims at investigating the effect of pH values and additives on the dispersion of two 1:1 dioctahedral phyllosilicates in the presence of water. Two model clays are used for this purpose, BIP kaolin and NZCC halloysite, presenting the same surface chemistry but different morphologies. The effect of sodium hexametaphosphate, sodium silicate and sodium carbonate is discussed. Kaolin and halloysite powders were first characterized using X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. Subsequently, suspensions containing 8 mass% of each clay were prepared with or without additives. Experimental measurements regarding the pH values, the zeta potential and the rheological behavior were performed to determine the most suitable additive. Results show that the conformation of halloysite particles changes regarding pH values of suspensions and is strongly related to the surface charges of these particles. At their natural pH values, halloysite and kaolin suspensions exhibit zeta potentials equal to -50 and -20 mV respectively. This trend indicates that halloysite-based suspensions are well dispersed compared to kaolin-based suspensions. Sodium hexametaphosphate is the most suitable dispersant for both clays. The rheological characterization regarding further applications in casting process indicates a shear-thinning behavior for all studied compositions. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Transmutation effects on long-term Cs retention in phyllosilicate minerals from first principles.

    PubMed

    Sassi, Michel; Okumura, Masahiko; Machida, Masahiko; Rosso, Kevin M

    2017-10-11

    The accidental release and incorporation of radiocesium into soil minerals represents a massive environmental, technical and social challenge. Accurately forecasting the evolving distribution and fate of long- and medium-lived isotopes such as 137 Cs and 134 Cs over decadal time scales is essential. The cesium cation has long been modeled as a strongly and selectively sorbed species into clay mineral interlayers; however, because of the time scales involved by the radioisotopes half-lives, the effects of radioactive decay on Cs retention have been unknown. We report density functional theory (DFT) simulations of transmutation effects of radiocesium on long-term Cs retention in phlogopite. The calculations show that the progressive appearance of daughter product Ba 2+ is accompanied by a proportional increase in thermodynamic driving force to preferentially discharge remaining Cs, both radioactive and stable, back into aqueous solution. Based on thermodynamic analysis, the findings indicate that radiocesium transmutation provides a mean to weaken the binding of Cs in phyllosilicate minerals, therefore potentially involving a premature re-release of Cs back into the environment. In the case where radiogenic Ba 2+ ions accumulate in the mineral, collateral effects would ultimately be an increase in the overall interlayer binding energy and a lower resorption capacity.

  19. Effect of organic matter on CO(2) hydrate phase equilibrium in phyllosilicate suspensions.

    PubMed

    Park, Taehyung; Kyung, Daeseung; Lee, Woojin

    2014-06-17

    In this study, we examined various CO2 hydrate phase equilibria under diverse, heterogeneous conditions, to provide basic knowledge for successful ocean CO2 sequestration in offshore marine sediments. We investigated the effect of geochemical factors on CO2 hydrate phase equilibrium. The three-phase (liquid-hydrate-vapor) equilibrium of CO2 hydrate in the presence of (i) organic matter (glycine, glucose, and urea), (ii) phyllosilicates [illite, kaolinite, and Na-montmorillonite (Na-MMT)], and (iii) mixtures of them was measured in the ranges of 274.5-277.0 K and 14-22 bar. Organic matter inhibited the phase equilibrium of CO2 hydrate by association with water molecules. The inhibition effect decreased in the order: urea < glycine < glucose. Illite and kaolinite (unexpandable clays) barely affected the CO2 hydrate phase equilibrium, while Na-MMT (expandable clay) affected the phase equilibrium because of its interlayer cations. The CO2 hydrate equilibrium conditions, in the illite and kaolinite suspensions with organic matter, were very similar to those in the aqueous organic matter solutions. However, the equilibrium condition in the Na-MMT suspension with organic matter changed because of reduction of its inhibition effect by intercalated organic matter associated with cations in the Na-MMT interlayer.

  20. Pharmaceutical grade phyllosilicate dispersions: the influence of shear history on floc structure.

    PubMed

    Viseras, C; Meeten, G H; Lopez-Galindo, A

    1999-05-10

    The effect of mixing conditions on the flow curves of some clay-water dispersions was studied. Two Spanish fibrous phyllosilicates (sepiolite from Vicálvaro and palygorskite from Turón) and a commercial bentonite (Bentopharm Copyright, UK) were selected as model clays. The disperse systems were made up using a rotor-stator mixer working at two different mixing rates (1000 and 8000 rpm), for periods of 1 and 10 min. Rheological measurements were taken and the corresponding flow curves obtained immediately after interposition and then after a period of 24 h under low shear caused by a roller apparatus. Aqueous sepiolite dispersions showed the highest viscosity and were easily interposed, whereas palygorskite dispersions were more difficult to obtain, resulting in low to medium viscosity gels. Bentonite dispersions provided medium viscosity systems, which greatly increased their viscosity after the low shear treatment (as a result of swelling), whereas the viscosity of the fibrous clays stayed at approximately the same values or even decreased. A linear relation was found between mixing energy and apparent viscosity in the bentonite systems, while apparent viscosity in the sepiolite samples was related to mixing power, with minor influence of mixing times. All the systems studied had thixotropic behaviour, changing from clearly positive to even negative thixotropy in some palygorskite systems. Finally, we studied the effect of drastic pH changes on the system structure. Results showed that rheological properties were highly sensitive to pH in the fibrous dispersions, but less sensitive behaviour was found in the laminar clay systems. Copyright.

  1. Surface materials map of Afghanistan: carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Dudek, Kathleen B.; Livo, Keith E.

    2012-01-01

    This map shows the distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of HyMap imaging spectrometer data of Afghanistan. Using a NASA (National Aeronautics and Space Administration) WB-57 aircraft flown at an altitude of ~15,240 meters or ~50,000 feet, 218 flight lines of data were collected over Afghanistan between August 22 and October 2, 2007. The HyMap data were converted to apparent surface reflectance, then further empirically adjusted using ground-based reflectance measurements. The reflectance spectrum of each pixel of HyMap data was compared to the spectral features of reference entries in a spectral library of minerals, vegetation, water, ice, and snow. This map shows the spatial distribution of minerals that have diagnostic absorption features in the shortwave infrared wavelengths. These absorption features result primarily from characteristic chemical bonds and mineralogical vibrations. Several criteria, including (1) the reliability of detection and discrimination of minerals using the HyMap spectrometer data, (2) the relative abundance of minerals, and (3) the importance of particular minerals to studies of Afghanistan's natural resources, guided the selection of entries in the reference spectral library and, therefore, guided the selection of mineral classes shown on this map. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated. Minerals having similar spectral features were less easily discriminated, especially where the minerals were not particularly abundant and (or) where vegetation cover reduced the absorption strength of mineral features. Complications in reflectance calibration also affected the detection and identification of minerals.

  2. Some features associated with organosilane groups grafted by the sol-gel process onto synthetic talc-like phyllosilicate.

    PubMed

    Sales, José A A; Petrucelli, Giovanni C; Oliveira, Fernando J V E; Airoldi, Claudio

    2006-05-01

    Two new lamellar inorganic-organic magnesium silicates have been successfully synthesized by using sol-gel based processes under mild temperature conditions. The talc-organosilicates derived using two silylating agents as the silicon source, (i) 3-chloropropyltrimethoxysilane, and (ii) from the attachment of 5-amino-1,3,4-thiadiazole-2-thiol molecule to this precursor agent, yielded PhMg-Cl and PhMg-Tz phyllosilicates. These organoclays were characterized through elemental analyses, infrared spectroscopy, X-ray diffractometry, surface area, thermogravimetry, and carbon and silicon solid state nuclear magnetic resonance spectroscopy. The results confirmed the presence of organic moieties covalently bonded to the inorganic silicon sheet network of the 2:1 class of phyllosilicates, with a density of organic molecules of 6.6+/-0.1 and 2.7+/-0.2 mmol g(-1) anchored on the inorganic layer and with interlayer distances of 1158 and 1628 pm, respectively. The nuclear magnetic resonances results in the solid state are in agreement with the sequence of carbons distributed in the pendant chains of the original silylating agents and the silicon bonded to oxygen atoms or carbon atoms of the inorganic sheets, as expected for the organically functionalized phyllosilicates. The enhanced potential of the new compound PhMg-Tz as a multi property material was explored in adsorbing cations from aqueous solution. The basic sulfur and nitrogen centers attached to the pendant chains inside the lamellar cavity can coordinate mercury, by presenting an isotherm saturated at 0.19 mmol g(-1) of this heavy metal. The functionality of this organoclay-like material expresses its potential for heavy cation removal from an ecosystem.

  3. Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials

    NASA Technical Reports Server (NTRS)

    Rampe, Elizabeth B.; Morris, Richard V.; Chipera, Steve; Bish, David L.; Bristow, Thomas; Archer, Paul Douglas; Blake, David; Achilles, Cherie; Ming, Douglas W.; Vaniman, David; hide

    2013-01-01

    The Curiosity Rover landed on the Peace Vallis alluvial fan in Gale crater on August 5, 2012. A primary mission science objective is to search for past habitable environments, and, in particular, to assess the role of past water. Identifying the minerals and mineraloids that result from aqueous alteration at Gale crater is essential for understanding past aqueous processes at the MSL landing site and hence for interpreting the site's potential habitability. X-ray diffraction (XRD) data from the CheMin instrument and evolved gas analyses (EGA) from the SAM instrument have helped the MSL science team identify phases that resulted from aqueous processes: phyllosilicates and amorphous phases were measure in two drill samples (John Klein and Cumberland) obtained from the Sheepbed Member, Yellowknife Bay Fm., which is believed to represent a fluvial-lacustrine environment. A third set of analyses was obtained from scoop samples from the Rocknest sand shadow. Chemical data from the APXS instrument have helped constrain the chemical compositions of these secondary phases and suggest that the phyllosilicate component is Mg-enriched and the amorphous component is Fe-enriched, relatively Si-poor, and S- and H-bearing. To refine the phyllosilicate and amorphous components in the samples measured by MSL, we measured XRD and EGA data for a variety of relevant natural terrestrial phyllosilicates and synthetic mineraloids in laboratory testbeds of the CheMin and SAM instruments. Specifically, Mg-saturated smectites and vermiculites were measured with XRD at low relative humidity to understand the behavior of the 001 reflections under Mars-like conditions. Our laboratory XRD measurements suggest that interlayer cation composition affects the hydration state of swelling clays at low RH and, thus, the 001 peak positions. XRD patterns of synthetic amorphous materials, including allophane, ferrihydrite, and hisingerite were used in full-pattern fitting (FULLPAT) models to help

  4. Exploring the potential of phyllosilicate minerals as potassium fertilizers using sodium tetraphenylboron and intensive cropping with perennial ryegrass

    PubMed Central

    Li, Ting; Wang, Huoyan; Wang, Jing; Zhou, Zijun; Zhou, Jianmin

    2015-01-01

    In response to addressing potassium (K) deficiency in soil and decreasing agricultural production costs, the potential of K-bearing phyllosilicate minerals that can be directly used as an alternative K source has been investigated using sodium tetraphenylboron (NaTPB) extraction and an intensive cropping experiment. The results showed that the critical value of K-release rate and leaf K concentration was 3.30 g kg−1 h−1 and 30.64 g (kg dry matter)−1, respectively under the experimental conditions. According to this critical value, the maximum amount of released K that could be utilized by a plant with no K deficiency symptoms was from biotite (27.80 g kg−1) and vermiculite (5.58 g kg−1), followed by illite, smectite and muscovite with 2.76, 0.88 and 0.49 g kg−1, respectively. Ryegrass grown on phlogopite showed K deficiency symptoms during the overall growth period. It is concluded that biotite and vermiculite can be directly applied as a promising and sustainable alternative to the use of classical K fertilizers, illite can be utilized in combination with soluble K fertilizers, whereas muscovite, phlogopite and smectite may not be suitable for plant growth. Further field experiments are needed to assess the use of these phyllosilicate minerals as sources of K fertilizer. PMID:25782771

  5. Phyllosilicate analysis capabilities of the CheMin mineralogical instrument on the Mars Science Laboratory (MSL '11) Curiosity Rover

    NASA Astrophysics Data System (ADS)

    Blake, D. F.; Bish, D. L.; Vaniman, D. T.; Chipera, S.; Bristow, T. F.; Sarrazin, P.

    2011-12-01

    The CheMin mineralogical instrument on the MSL '11 Curiosity rover will return quantitative X-ray diffraction data (XRD) from scooped soil samples and drilled rock powders collected from the Mars surface. Samples of 45-65 mm3 from material sieved to <150 μm will be delivered through a funnel to one of 27 reuseable sample cells (five additional cells on the sample wheel contain diffraction or fluorescence standards). Sample cells are 8-mm diameter discs with 7-μm thick Mylar or Kapton windows spaced 170 μm apart. Within this volume, the sample is shaken by piezoelectric vibration at sonic frequencies, causing the powder to flow past a narrow, collimated X-ray beam in random orientations over the course of an analysis. In this way, diffraction patterns exhibiting little to no preferred orientation can be obtained even from minerals normally exhibiting strong preferred orientation such as phyllosilicates. Individual analyses will require several hours over one or more Mars sols. For typical well-ordered minerals, CheMin has a Minimum Detection Limit (MDL) of <3% by mass, an accuracy of better than 15% and a precision of better than 10% for phases present in concentrations >4X MDL (12%). The resolution of the diffraction patterns is 0.30 degrees 2θ, and the angular measurement range is 4-55 degrees 2θ. With this performance, CheMin can identify and distinguish a number of clay minerals. For example, discrimination between 1:1 phyllosilicates (such as the kaolin minerals), with repeat distances of ~7Å, and smectites (e.g., montmorillonite, nontronite, saponite), with repeat distances from 10-15Å, is straightforward. However, it is important to note that the variety of treatments used in terrestrial laboratories to aid in discrimination of clay minerals will not be accessible on Mars (e.g., saturation with ethylene glycol vapor, heat treatments). Although these treatments will not be available on Mars, dehydration within the CheMin instrument could be used to

  6. Organics-bearing Clays from the Rio Tinto (spain): A Novel Analog for the Phyllosilicates Outcrops Seen By Omega-mex

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, Rosalba

    2007-12-01

    The Rio Tinto (RT) is considered an important analog of Sinus Meridiani on Mars and an ideal model analog for a subsurface Martian setting [1]. The RT system comprises the upper sequence of an acid rock drainage system where weathered iron -rich rocks, overlain a massive-pyrite deposit. The RT analog site is ideal for testing on the preservation of organics in hematite-rich vs. phyllosilicates-rich environments [3]. It is suggested here that RT near-surface rocks, which embed pockets of Clays, represent also a potential new model analog for the phyllosilicates-rich outcrops seen by OMEGA-MEx on the surface of Mars [5]. Results from the analysis of cores drilled under the 2005 Robotic experiment of the MARTE project (Borehole#7 Site 607cm) [2-3] are presented in this paper. Primary mineral assemblages include hematite, goethite, and Phyllosilicates e.g.,smectite, kaolinite, as quantified by X-ray diffraction [4]. Organic carbon is at low concentration (<0.05%) beneath the soil horizon in most cores dominated by iron minerals but is considerably higher in Phyllosilicate-rich levels i.e., 0.2-0.3Wt% at 385 -550 cm-depth [2-3]. Phyllosilicate-rich terrains have been identified OMEGA/MEx in the Nili Fossae, Mawrth Valles and Candor Chasma regions [e.g., 5]. These outcrops are surrounded by hematite-rich deposits, which are potentially barren in organics [6]. The potential of phyllosilicates to preserve higher amounts of organics/ biosignatures is well known for several Earth environments as well as the RT near subsurface. This potential brings a relevant element for the selection of candidate sites for the MSL mission [e.g., 1]. References: [1]Fernandez-Remolar et al.,2005 EPSL, 240,149-167; [2]Stoker et al., 2007; [3] Bonaccorsi et al., 2007; [4] Sutter et al., 2007 in Astrobiology,MARTE Spec. Issue; [5] Bibring et al., 2006, Science 312, 400-404; [6] Sumner, 2004, JGR 109. Anknowlegments: NASA-Postdoctoral-Program/C.Stoker, B.Sutter, A.F Davila and the MARTE team for

  7. Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, H. V., Jr.

    1995-01-01

    Visible and near-IR reflectivity, Mossbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration (Fe(3+)/Fe(sub tot)) and ranged from approx. 1000 nm (high-Ca pyroxene) to approx. 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the 850 and 1000 nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relatively high temperatures on a sporadic basis throughout

  8. Hematite, pyroxene, and phyllosilicates on Mars: Implications from oxidized impact melt rocks from Manicouagan Crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Golden, D. C.; Bell, James F., III; Lauer, H. V., Jr.

    1995-01-01

    Visible and near-IR refectivity, Moessbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to approximately 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration Fe(3+)/Fe(sub tot) and ranged from approximately 1000 nm (high-Ca pyroxene) to approximately 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the approximately 850 and approximately 1000nm bands observed in Martian reflectivity spectra. Manicouagan data also show that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relativly

  9. Evidence of phyllosilicates in Wooly Patch, an altered rock encountered at West Spur, Columbia Hills, by the Spirit rover in Gusev crater, Mars

    Wang, A.; Korotev, R.L.; Jolliff, B.L.; Haskin, L.A.; Crumpler, L.; Farrand, W. H.; Herkenhoff, K. E.; de Souza, Jr.; Kusack, A.G.; Hurowitz, J.A.; Tosca, N.J.

    2006-01-01

    On its traverse to Columbia Hills, the Mars Exploration Rover Spirit investigated an outcrop designated "Wooly Patch" that exhibited morphological, mineralogical, and geochemical characteristics at the extreme ends of ranges observed among rocks studied at West Spur, a westward projecting salient near the foot of the Columbia Hills, Gusev crater. The major-element composition and Fe-mineralogy, as determined by the Alpha-Particle X-ray Spectrometer and Mo??ssbauer Spectrometer, are inconsistent with any reasonable assemblage of basaltic minerals in that there is an excess of Si and Al. The combined data are best explained by the presence of 14-17% phyllosilicate minerals. Phyllosilicates that account for the composition and cation ratios include members of the kaolinite, serpentine, chlorite, and septechlorite groups. The potential existence of kaolinite-type Al-rich phyllosilicates within the Wooly Patch outcrop suggests a mildly acidic environment (pH 4-6) in the past and an open hydrologic system with good drainage conditions in the environment where these rocks were altered. Copyright 2006 by the American Geophysical Union.

  10. CaB2 S4 O16 : A Borosulfate Exhibiting a New Structure Type with Phyllosilicate Analogue Topology.

    PubMed

    Bruns, Jörn; Podewitz, Maren; Schauperl, Michael; Joachim, Bastian; Liedl, Klaus R; Huppertz, Hubert

    2017-11-27

    The reaction of Ca(CO 3 ) with H 3 BO 3 in oleum (20 % SO 3 ) yielded colorless single-crystals of CaB 2 S 4 O 16 (monoclinic, P2 1 /c, a=5.5188(2), b=15.1288(6), c=13.2660(6) Å, β=92.88(1)°, V=1106.22(8) Å 3 ). X-ray single-crystal structure analysis revealed a phyllosilicate-analogue anionic sub-structure, forming 2D infinite anionic layers, which exhibit an unprecedented arrangement of condensed twelve-membered (zwölfer) and four-membered (vierer) rings of corner-shared (SO 4 ) and (BO 4 ) tetrahedra. Charge compensation is achieved by Ca 2+ cations, residing exclusively above the centers of the twelve-membered rings. DFT investigations on the solid-state structure corroborate the experimental findings and allow for a detailed valuation of charge distribution within the anionic network and an assignment of vibrational frequencies. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A new technique for identification of minerals in hyperspectral images. Application to robust characterization of phyllosilicate deposits at Mawrth Vallis using CRISM images.

    NASA Astrophysics Data System (ADS)

    Parente, M.; Bishop, J. L.

    2008-12-01

    Mapping of Mars by MRO has revealed the presence of numerous small phyllosilicate outcrops. These are typically identified in CRISM images using "summary products" (Pelkey, 2007) that consist of band ratios, depths and spectral slopes around diagnostic wavelengths. The summary products are designed to capture spectral features related to both surface mineralogy and atmospheric gases and aerosols. Such products, as an analysis tool to characterize composition as well as a targeting tool to identify areas of mineralogical interest, have been successful in capturing the known diversity of the Martian surface, and in highlighting locations with strong spectral signatures. Here we present alternative mineral mapping technique that 1) aims to increase the robustness of mineral detections with respect to the specific CRISM artifacts, 2) takes advantage of the spatial context of each pixel and 3) develops new parameters for the discrimination of species in the phyllosilicates family. We include spatial context by evaluating spectral shapes, band depths and spectral slopes for the current pixel based on its spatial neighbors within the same geological unit. Furthermore, the parameters are based on estimates that are more robust to CRISM speckling noise that might alter the parameters and potentially the mineral interpretation. As an effort to distinguish between phyllosilicates species, we are augmenting the suite of existent parameters with a set of mineral parameters that involve the position, number and shapes of diagnostic phyllosilicate absorptions. We are comparing the effectiveness of this new approach to the summary product procedure. The study shows that homogeneous mineral maps and diagnostic spectral identifications are possible as a result of the application of such new parameters. We applied the technique to the discrimination of kaolinite in Mawrth Vallis. The experiments show several small kaolinite outcrops dispersed within the more extensive Al

  12. Soil properties controlling Zn speciation and fractionation in contaminated soils

    NASA Astrophysics Data System (ADS)

    Jacquat, Olivier; Voegelin, Andreas; Kretzschmar, Ruben

    2009-09-01

    We determined the speciation of Zn in 49 field soils differing widely in pH (4.1-7.7) and total Zn content (251-30,090 mg/kg) by using extended X-ray absorption fine structure (EXAFS) spectroscopy. All soils had been contaminated since several decades by inputs of aqueous Zn with runoff-water from galvanized power line towers. Pedogenic Zn species identified by EXAFS spectroscopy included Zn in hydroxy-interlayered minerals (Zn-HIM), Zn-rich phyllosilicates, Zn-layered double hydroxide (Zn-LDH), hydrozincite, and octahedrally and tetrahedrally coordinated sorbed or complexed Zn. Zn-HIM was only observed in (mostly acidic) soils containing less than 2000 mg/kg of Zn, reflecting the high affinity but limited sorption capacity of HIM. Zn-bearing precipitates, such as Zn-LDH and Zn-rich trioctahedral phyllosilicates, became more dominant with increasing pH and increasing total Zn content relative to available adsorption sites. Zn-LDH was the most abundant Zn-precipitate and was detected in soils with pH > 5.2. Zn-rich phyllosilicates were detected even at lower soil pH, but were generally less abundant than Zn-LDH. Hydrozincite was only identified in two calcareous soils with extremely high Zn contents. In addition to Zn-LDH, large amounts of Zn in highly contaminated soils were mainly accumulated as sorbed/complexed Zn in tetrahedral coordination. Soils grouped according to their Zn speciation inferred from EXAFS spectroscopy mainly differed with respect to soil pH and total Zn content. Clear differences were observed with respect to Zn fractionation by sequential extraction: From Zn-HIM containing soils, most of the total Zn was recovered in the exchangeable and the most recalcitrant fractions. In contrast, from soils containing the highest percentage of Zn-precipitates, Zn was mainly extracted in intermediate extraction steps. The results of this study demonstrate that soil pH and Zn contamination level relative to available adsorption sites are the most important

  13. 3-aminopropyl functionalized magnesium phyllosilicate as an organoclay based drug carrier for improving the bioavailability of flurbiprofen.

    PubMed

    Yang, Liang; Choi, Soo-Kyung; Shin, Hyun-Jae; Han, Hyo-Kyung

    2013-01-01

    This study aimed to develop an oral delivery system using clay-based organic-inorganic hybrid materials to improve the bioavailability of the drug, flurbiprofen, which is poorly soluble in water. 3-aminopropyl functionalized magnesium phyllosilicate (AMP clay) was synthesized by a one-pot direct sol-gel method, and then flurbiprofen (FB) was incorporated into AMP clay (FB-AMP) at different drug/clay ratios. The structural characteristics of AMP and FB-AMP formulation were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. Among tested formulations, FB-AMP(3), dramatically increased the dissolution of FB and achieved rapid and complete drug release within 2 hours. More than 60% of FB was released from FB-AMP(3) after 30 minutes; the drug was completely dissolved in the water within 2 hours. Under the acidic condition (pH 1.2), FB-AMP(3) also increased the dissolution of FB by up to 47.1% within 1 hour, which was three-fold higher than that of untreated FB. Furthermore, following an oral administration of FB-AMP(3) to Sprague-Dawley rats, the peak plasma concentration and area under the plasma concentration-time curve of FB increased two-fold, and the time to reach the peak plasma concentration was shortened compared with that in the untreated FB. This result suggests that the oral drug delivery system using clay-based organic-inorganic hybrid material might be useful to improve the bioavailability of FB.

  14. 3-aminopropyl functionalized magnesium phyllosilicate as an organoclay based drug carrier for improving the bioavailability of flurbiprofen

    PubMed Central

    Yang, Liang; Choi, Soo-Kyung; Shin, Hyun-Jae; Han, Hyo-Kyung

    2013-01-01

    This study aimed to develop an oral delivery system using clay-based organic–inorganic hybrid materials to improve the bioavailability of the drug, flurbiprofen, which is poorly soluble in water. 3-aminopropyl functionalized magnesium phyllosilicate (AMP clay) was synthesized by a one-pot direct sol-gel method, and then flurbiprofen (FB) was incorporated into AMP clay (FB-AMP) at different drug/clay ratios. The structural characteristics of AMP and FB-AMP formulation were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. Among tested formulations, FB-AMP(3), dramatically increased the dissolution of FB and achieved rapid and complete drug release within 2 hours. More than 60% of FB was released from FB-AMP(3) after 30 minutes; the drug was completely dissolved in the water within 2 hours. Under the acidic condition (pH 1.2), FB-AMP(3) also increased the dissolution of FB by up to 47.1% within 1 hour, which was three-fold higher than that of untreated FB. Furthermore, following an oral administration of FB-AMP(3) to Sprague-Dawley rats, the peak plasma concentration and area under the plasma concentration-time curve of FB increased two-fold, and the time to reach the peak plasma concentration was shortened compared with that in the untreated FB. This result suggests that the oral drug delivery system using clay-based organic–inorganic hybrid material might be useful to improve the bioavailability of FB. PMID:24204143

  15. Phyllosilicate weathering pathways in chlorite-talc bearing soil parent materials, D.R. Congo: early findings.

    NASA Astrophysics Data System (ADS)

    Dumon, Mathijs; Oostermeyer, Fran; Timmermans, Els; De Meulemeester, Aschwin; Mees, Florias; Van Driessche, Isabel; Erens, Hans; Bazirake Mujinya, Basile; Van Ranst, Eric

    2015-04-01

    The study of the formation and transformation of clay minerals is of the upmost importance to understand soil formation and to adjust land-use management to the land surface conditions. These clay minerals determine to a large extent the soil physical and chemical properties. It is commonly observed that over time the mineralogy of any parent material is transformed to a simple assemblage composed mostly of Al and Fe oxides and low-activity clays, e.g. kaolinite. This is especially obvious in the humid tropics, which have been protected from glacial erosion, allowing deep, highly weathered soils to form. Despite the abundant presence of kaolinite in these soils, its formation pathways are still under debate: either neoformation by dissolution-crystallisation reactions or solid-state transformation of 2:1 phyllosilicates. To elucidate this, weathering sequences in a unique 40 m core taken below a termite mound, reaching a talc-chlorite bearing substrate in the Lubumbashi area, Katanga, DR Congo are being investigated in detail using a.o. quantitative X-ray diffraction analysis, chemical characterization, micromorphology and µXRF-scanning with the main objective to improve the understanding of the formation pathways of kaolinite subgroup minerals in humid tropical environments. Based on an initial characterization of the core, two zones of interest were selected for more detailed analysis, for which the early findings will be presented. The first zone extends from ca. 9 m to 11 m below the surface is dominated by kaolinite but shows early traces of primary talc and micas. The second zone extends from 34 to 36 m below the surface and contains large amounts of chlorite, with smaller amounts of talc, micas and kaolinite.

  16. Radiation-Damage Resistance in Phyllosilicate Minerals From First Principles and Implications for Radiocesium and Strontium Retention in Soils

    SciT

    Sassi, Michel; Rosso, Kevin M.; Okumura, Masahiko

    Accidental discharges of the hazardous nuclear fission products 137Cs+ and 90Sr2+ into the environment, such as during the Fukushima Dai-ichi nuclear accident, have repeatedly occurred throughout the nuclear age. Numerous studies of their fate and transport in soils and sediments have demonstrated their strong and selective binding to phyllosilicates such as clay minerals, primarily via cation exchange into interlayer sites. The locally concentrated amounts of these radioactive beta-emitters that can be found in these host minerals raises important questions regarding the long-term interplay and durability of radioisotope-clay association, which is not well known. This study goes beyond the usual short-termmore » focus to address the permanence of radioisotope retention in clay minerals, by developing a general theoretical understanding of their resistance to defect creation. We report ab initio molecular dynamics (AIMD) calculations of the threshold displacement energy (TDE) of each symmetry-unique atomic specie comprising the unit cell of model vermiculite. The determined TDE values are material specific and radiation independent. We use them to estimate the probability of Frenkel pair creation via direct electron-ion collision, as could be induced by the passage of a high energy electron emitted during the beta-decay of 137Cs, 90Sr and daughter 90Y. For 137Cs and 90Sr, we found that the probability is about 36%, while for 90Y the probability is much higher with about 89%. The long-term retention picture that emerges is that decay will progressively alter the clay interlayer structure and charge, likely leading to delamination of the clay and re-release of residual parent isotopes. Future work examining the effect of Frenkel defect accumulation on the binding energy of parent and daughter radionuclides in the interlayer is thus justifiable, and potentially important for accurate long-term forecasting of radionuclide transport in the environment.« less

  17. Identification and spatial distribution of light-toned deposits enriched in Al-phyllosilicates on the plateaus around Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Le Deit, L.; Flahaut, J.; Quantin, C.; Allemand, P.

    2009-12-01

    The plateaus around Valles Marineris consist in series of mafic rocks suggested to be flood basalts (McEwen et al., 1998), lavas interbedded with sediments (Malin and Edgett, 2000), layered intrusive rocks (Williams et al., 2003), or lava flows dated from the Noachian to the late Hesperian epochs (Scott and Carr, 1978). Recent studies show the occurrence of light layered deposits of hundred meters thick cropping out on plateaus near Ius Chasma, Melas Chasma, Candor Chasma, Juventae Chasma and Ganges Chasma deposited during the Hesperian epoch by fluvio-lacustrine processes (Weitz et al., 2009), or by air-fall processes (Le Deit et al., 2009). These layered deposits are enriched in hydrated minerals including opaline silica (Milliken et al., 2008), hydroxylated ferric sulfates (Bishop et al., 2009), and possibly Al-rich phyllosilicates (Le Deit et al., 2009). We identified another type of formation corresponding to light-toned massive deposits cropping out around Valles Marineris. It appears that these light-toned deposits are associated to bright, rough, and highly cratered terrains, located beneath a dark and thin capping unit. Previous studies report the occurrence of phyllosilicates on few locations around Valles Marineris based on OMEGA data analyses (Gondet et al., 2007; Carter et al., 2009). The analysis of CRISM data show that the light-toned deposits are associated with spectra displaying absorption bands at 1.4 μm, 1.9 μm, and a narrow band at 2.2 μm. These spectral characteristics are consistent with the presence of Al-rich phyllosilicates such as montmorillonite, or illite in the light-toned deposits. They constitute dozens of outcrops located on the plateaus south and east of Coprates Chasma and Capri Chasma, and west of Ganges Chasma. All outcrops investigated so far are present over Noachian terrains mapped as the unit Npl2 by Scott and Tanaka (1986), and Witbeck et al. (1991). These light-toned deposits could result from in situ aqueous alteration

  18. The Effects of Punctuated Warm and Wet Environments on Phyllosilicate Formation - or How Long was Early Mars Wet?

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Baker, L.; Rampe, E. B.; Velbel, M. A.

    2016-12-01

    Abundant phyllosilicates and aqueous minerals are observed nearly everywhere we can see the ancient rocks on Mars [1,2]. Most bountiful among these is Fe/Mg-smectite. So, what can these smectite clays tell us about the early Martian environment? Studies of smectite formation [3,4] indicate that they form faster at elevated (>100 °C) temperatures. There is a trade-off between temperature and time such that lower temperatures require more time for smectite formation. We postulate that short-term warm and wet environments could have enabled formation of the observed smectite occurrences on Mars without requiring long-term bodies of water on the planet. Smectites form in weathering environments by transformation from primary silicates or by neoformation from allophane and related amorphous materials [3,5]. The highest smectite abundances are observed in low rainfall climates (<50 cm/yr), while kaolins and vermiculites require significantly higher rainfall levels [3]. Smectites formed in low temperature (<100 °C) waters are typically mixed with amorphous aluminosilicates [4], which implies incomplete reaction. Allophane and imogolite form in near neutral waters in well-drained environments as Al and Si are leached from volcanic ash and tephra [6]. In dry environments allophane and related nanophase materials can persist long-term. Allophane and imogolite have been identified in Martian surface material from orbit [7,8] and amorphous components have been found at Gale crater [9]. Because amorphous phases such as opal, ferrihydrite, allophane and imogolite are highly reactive and mobile in aqueous environments, finding these on the surface of Mars and in martian meteorites [10] suggests that the planet has been dry since their formation. In fact, Bishop & Rampe [7] suggest that the transition from smectite to allophane on Mars marks a change in climate. References: [1] Carter J. et al. (2015) Icarus, 248, 373. [2] Murchie S.L. et al. (2009) JGR, 114. [3] Eberl D.D. et

  19. Equilibrium chemistry down to 100 K. Impact of silicates and phyllosilicates on the carbon to oxygen ratio

    NASA Astrophysics Data System (ADS)

    Woitke, P.; Helling, Ch.; Hunter, G. H.; Millard, J. D.; Turner, G. E.; Worters, M.; Blecic, J.; Stock, J. W.

    2018-06-01

    We have introduced a fast and versatile computer code, GGCHEM, to determine the chemical composition of gases in thermo-chemical equilibrium down to 100 K, with or without equilibrium condensation. We have reviewed the data for molecular equilibrium constants, kp(T), from several sources and discussed which functional fits are most suitable for low temperatures. We benchmarked our results against another chemical equilibrium code. We collected Gibbs free energies, ΔGf⊖, for about 200 solid and liquid species from the NIST-JANAF database and the geophysical database SUPCRTBL. We discussed the condensation sequence of the elements with solar abundances in phase equilibrium down to 100 K. Once the major magnesium silicates Mg2SiO4[s] and MgSiO3[s] have formed, the dust to gas mass ratio jumps to a value of about 0.0045 which is significantly lower than the often assumed value of 0.01. Silicate condensation is found to increase the carbon to oxygen ratio (C/O) in the gas from its solar value of 0.55 up to 0.71, and, by the additional intake of water and hydroxyl into the solid matrix, the formation of phyllosilicates at temperatures below 400 K increases the gaseous C/O further to about 0.83. Metallic tungsten (W) is the first condensate found to become thermodynamically stable around 1600-2200 K (depending on pressure), several hundreds of Kelvin before subsequent materials such as zirconium dioxide (ZrO2) or corundum (Al2O3) can condense. We briefly discuss whether tungsten, despite its low abundance of 2 × 10-7 times the silicon abundance, could provide the first seed particles for astrophysical dust formation. GGCHEM code is publicly available at http://https://github.com/pw31/GGchemTable D.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/614/A1

  20. Strength of the Subduction Plate Interface beneath the Seismogenic Zone: A Microstructural Investigation of Deformation Mechanisms within a Phyllosilicate- and Amphibole-rich Shear Zone

    NASA Astrophysics Data System (ADS)

    Seyler, C.; Kirkpatrick, J. D.; Šilerová, D.

    2017-12-01

    Localization of strain at plate boundaries requires rheological weakening of the lithosphere. The rheology of the subduction plate interface is dictated by the dominant grain-scale deformation mechanisms. However, little is known about the deformation mechanisms within phases commonly found in subduction zones, such as phyllosilicates and amphiboles. We investigate the Leech River Shear Zone on Vancouver Island, British Columbia to explore deformation processes downdip of the seismogenic zone and evaluate the bulk rheology of the plate interface. This shear zone juxtaposes a metamorphosed accretionary prism against a metabasaltic oceanic plateau, representing a paleo-plate interface from the ancient Cascadia subduction zone. Preliminary geothermometry results record a prograde deformation temperature of 573.6±11.2 ˚C in the overriding accretionary wedge, and the hornblende-chlorite-epidote-plagioclase mineral assemblage suggests upper greenschist to lower amphibolite facies metamorphism of the downgoing oceanic crust. Detailed mapping of the plate interface documents a 200 m wide mylonitic shear zone developed across the lithologic contact. Asymmetric shear fabrics, isoclinal folding, boudinage, and a steeply plunging, penetrative stretching lineation are consistent with sinistral-oblique subduction. Numerous discordant quartz veins are variably sheared into sigmoidal shapes as well as isoclinally folded and boudinaged, indicating cyclical synkinematic fracture and vein formation. At the grain-scale, interconnected, anastomosing layers of muscovite, chlorite, and graphite in the accretionary prism rocks likely deformed through kinking and dislocation glide. Framework minerals such as quartz and feldspar deformed by dislocation creep. In the metabasalt, hornblende and chlorite form a continuous S—C fabric in which asymmetric hornblende porphyroclasts deformed by rigid grain rotation and dissolution-precipitation creep. The strength of the subduction plate

  1. Mineralogical, chemical, organic and microbial properties of subsurface soil cores from Mars Desert Research Station (Utah, USA): Phyllosilicate and sulfate analogues to Mars mission landing sites

    NASA Astrophysics Data System (ADS)

    Stoker, Carol R.; Clarke, Jonathan; Direito, Susana O. L.; Blake, David; Martin, Kevin R.; Zavaleta, Jhony; Foing, Bernard

    2011-07-01

    We collected and analysed soil cores from four geologic units surrounding Mars Desert Research Station (MDRS) Utah, USA, including Mancos Shale, Dakota Sandstone, Morrison formation (Brushy Basin member) and Summerville formation. The area is an important geochemical and morphological analogue to terrains on Mars. Soils were analysed for mineralogy by a Terra X-ray diffractometer (XRD), a field version of the CheMin instrument on the Mars Science Laboratory (MSL) mission (2012 landing). Soluble ion chemistry, total organic content and identity and distribution of microbial populations were also determined. The Terra data reveal that Mancos and Morrison soils are rich in phyllosilicates similar to those observed on Mars from orbital measurements (montmorillonite, nontronite and illite). Evaporite minerals observed include gypsum, thenardite, polyhalite and calcite. Soil chemical analysis shows sulfate the dominant anion in all soils and SO4>>CO3, as on Mars. The cation pattern Na>Ca>Mg is seen in all soils except for the Summerville where Ca>Na. In all soils, SO4 correlates with Na, suggesting sodium sulfates are the dominant phase. Oxidizable organics are low in all soils and range from a high of 0.7% in the Mancos samples to undetectable at a detection limit of 0.1% in the Morrison soils. Minerals rich in chromium and vanadium were identified in Morrison soils that result from diagenetic replacement of organic compounds. Depositional environment, geologic history and mineralogy all affect the ability to preserve and detect organic compounds. Subsurface biosphere populations were revealed to contain organisms from all three domains (Archaea, Bacteria and Eukarya) with cell density between 3.0×106 and 1.8×107 cells ml-1 at the deepest depth. These measurements are analogous to data that could be obtained on future robotic or human Mars missions and results are relevant to the MSL mission that will investigate phyllosilicates on Mars.

  2. Spitzer IRS Spectroscopy of the 10 Myr-Old EF Cha Debris Disk: Evidence for Phyllosilicate-Rich Dust in the Terrestrial Zone

    NASA Technical Reports Server (NTRS)

    Currie, Thayne; Lisse, Carey M.; Sicillia-Aguilar, Aurora; Rieke, George H.; Su, Kate Y. L.

    2011-01-01

    We describe Spitzer IRS spectroscopic observations of the approx. 10 Myr-old star, EF Chao Compositional modeling of the spectra from 5 micron to 35 micron confirms that it is surrounded by a luminous debris disk with L(sub D)/L(sub *) approx. 10(exp -3), containing dust with temperatures between 225 K and 430 K characteristic of the terrestrial zone. The EF Cha spectrum shows evidence for many solid-state features, unlike most cold, low-luminosity debris disks but like some other 10-20 Myr-old luminous, warm debris disks (e.g. HD 113766A). The EF Cha debris disk is unusually rich in a species or combination of species whose emissivities resemble that of finely-powdered, laboratory-measured phyllosilicate species (talc, saponite, and smectite), which are likely produced by aqueous alteration of primordial anhydrous rocky materials. The dust and, by inference, the parent bodies of the debris also contain abundant amorphous silicates and metal sulfides, and possibly water ice. The dust's total olivine to pyroxene ratio of approx. 2 also provides evidence of aqueous alteration. The large mass volume of grains with sizes comparable to or below the radiation blow-out limit implies that planetesimals may be colliding at a rate high enough to yield the emitting dust but not so high as to devolatize the planetesimals via impact processing. Because phyllosilicates are produced by the interactions between anhydrous rock and warm, reactive water, EF Cha's disk is a likely signpost for water delivery to the terrestrial zone of a young planetary system.

  3. Hyperspectral surface materials map of quadrangle 3568, Pul-e Khumri (503) and Charikar (504) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  4. Hyperspectral surface materials map of quadrangle 3562, Khawja-Jir (403) and Murghab (404) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  5. Hyperspectral surface materials map of quadrangle 3462, Herat (409) and Chishti Sharif (410) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  6. Hyperspectral surface materials map of quadrangle 3368, Ghazni (515) and Gardez (516) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  7. Hyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  8. Hyperspectral surface materials map of quadrangle 3466, La`l wa Sar Jangal (507) and Bamyan (508) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  9. Hyperspectral surface materials map of quadrangle 3364, Pasaband (417) and Markaz-e Kajiran (418) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  10. Hyperspectral surface materials map of quadrangle 3264, Naw Zad-Musa Qala (423) and Dihrawud (424) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  11. Hyperspectral surface materials map of quadrangle 3266, Uruzgan (519) and Moqur (520) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  12. Hyperspectral surface materials map of quadrangle 3470, Jalalabad (511) and Chaghasaray (512) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  13. Hyperspectral surface materials map of quadrangle 3166, Jaldak (701) and Maruf-Nawa (702) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  14. Hyperspectral surface materials map of quadrangle 3362, Shindand (415) and Tulak (416) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  15. Hyperspectral surface materials map of quadrangle 3268, Khayr Kot (521) and Urgun (522) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  16. Hyperspectral surface materials map of quadrangle 3262, Farah (421) and Hokumat-e-pur-Chaman (422) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  17. Hyperspectral surface materials map of quadrangle 3366, Gizab (513) and Nawer (514) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  18. Hyperspectral surface materials map of quadrangle 3770, Faizabad (217) and Parkhaw (218) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  19. Hyperspectral surface materials map of quadrangle 3570, Tagab-e-Munjan (505) and Asmar-Kamdesh (506) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  20. Hyperspectral surface materials map of quadrangle 3670, Jurm-Kishim (223) and Zebak (224) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  1. Hyperspectral Surface Materials Map of Quadrangle 3566, Sangcharak (501) and Sayghan-o-Kamard (502) Quadrangles, Afghanistan, Showing Carbonates, Phyllosilicates, Sulfates, Altered Minerals, and Other Materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  2. Hyperspectral surface materials map of quadrangle 3162, Chakhansur (603) and Kotalak (604) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  3. Hyperspectral surface materials map of quadrangle 3164, Lashkar Gah (605) and Kandahar (606) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  4. SAM-Like Evolved Gas Analyses of Phyllosilicate Minerals and Applications to SAM Analyses of the Sheepbed Mudstone, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    McAdam, A. C.; Franz, H. B.; Mahaffy, P. R.; Eigenbrode, J. L.; Stern, J. C.; Brunner, B.; Sutter, B.; Archer, P. D.; Ming , D. W.; Morris, R. V.; hide

    2014-01-01

    While in Yellowknife Bay, the Mars Science Laboratory Curiosity rover collected two drilled samples, John Klein (hereafter "JK") and Cumberland ("CB"), from the Sheepbed mudstone, as well as a scooped sample from the Rocknest aeolian bedform ("RN"). These samples were sieved by Curiosity's sample processing system and then several subsamples of these materials were delivered to the Sample Analysis at Mars (SAM) instrument suite and the CheMin X-ray diffraction/X-ray fluorescence instrument. CheMin provided the first in situ X-ray diffraction-based evidence of clay minerals on Mars, which are likely trioctahedral smectites (e.g., Fe-saponite) and comprise 20 wt% of the mudstone samples [1]. SAM's evolved gas analysis (EGA) mass spectrometry analyses of JK and CB subsamples, as well as RN subsamples, detected H2O, CO2, O2, H2, SO2, H2S, HCl, NO, OCS, CS2 and other trace gases evolved during pyrolysis. The identity of evolved gases and temperature( s) of evolution can augment mineral detection by CheMin and place constraints on trace volatile-bearing phases present below the CheMin detection limit or those phases difficult to characterize with XRD (e.g., X-ray amorphous phases). Here we will focus on the SAM H2O data, in the context of CheMin analyses, and comparisons to laboratory SAM-like analyses of several phyllosilicate minerals including smectites.

  5. Hyperspectral surface materials map of quadrangle 3564, Jowand (405) and Gurziwan (406) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan.Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines.The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  6. Hyperspectral surface materials map of quadrangle 3464, Shahrak (411) and Kasi (412) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan.Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines.The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  7. Rb-Sr and K-Ar age of globular phyllosilicates and biostratigraphy of the Riphean deposits of the Olenek Uplift (North Siberia)

    NASA Astrophysics Data System (ADS)

    Zaitseva, T. S.; Gorokhov, I. M.; Semikhatov, M. A.; Ivanovskaya, T. A.; Kuznetsov, A. B.; Dorzhieva, O. V.

    2017-11-01

    This work presents results of the complex mineralogical, geochemical, and isotope-geochronological investigation of globular dioctahedral 2: 1 phyllosilicates (GPS) of the illite-glauconite series from the Riphean sequences of the Olenek Uplift. It is established that GPS (glauconite, Al-glauconite, Fe-illite) in deposits of the Arymass, Debengda, and Khaipakh formations are represented by mixed-layer varieties of two types: (1) with relatively low (<10%) and (2) higher (10-20%) contents of expandable layers. Among the mixed-layer varieties are those with disordered alternation of micaceous and smectite layers (R = 0), as well as with tendency to ordering (R ≥ 1). The parameter b of an elementary cell of minerals varies from 9.18 to 9.72 Å. The Rb-Sr age dating of GPS was first carried out in combination with the calculation of theoretical pattern of the cation distribution in the mineral structure and comparison of the calculation results obtained with the Mössbauer and IR spectroscopy data. This approach is based on the assumption that development and evolution of isotope systems in GPS are synchronous with the evolution of the crystalline structure of the mineral at various stages of the geological and geochemical history of the development of sedimentary units. Analysis of the obtained data allows us to state that the structural features of the Riphean GPS from the Olenek section reflect the early diagenetic stages of the formation of the minerals studied. The 87Sr/86Sr initial ratios in the studied sediments are consistent with the range of variations in this ratio in the Middle Riphean Ocean (0.7049-0.7061). The Rb-Sr and K-Ar ages of the GPS of the Arymass (1305 ± 8 and 1302 Ma, respectively), Debengda (1265 ± 12 and 1284 ± 22 Ma), and Khaipakh (1172 ± 18 and 1112 ± 24 Ma) formations in the Olenek Uplift section are close to the accumulation time of corresponding deposits and, correspondingly, have significance for stratigraphic correlations.

  8. Magnetic anisotropy of some phyllosilicates

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Werner, Tomasz

    1994-08-01

    Magnetic susceptibility, anisotropy of susceptibility and hysteresis of single microcrystals of chlorite, biotite, phlogopite, muscovite, zinnwaldite and fuchsite were measured in low and high magnetic fields with an alternating gradient force magnetometer (Micromag). Their properties are sufficient to account for the low field susceptibility (AMS) of most micaceous rocks. Nearly all samples show some ferromagnetic contribution at low fields due to inclusions of pseudosingle domain and multidomain magnetite. The paramagnetic contribution isolated at high fields usually exceeds the ferromagnetic contribution. The paramagnetic susceptibility is intrinsic to the silicate lattice and agrees with values predicted from chemical composition within the limits of error. The minimum susceptibility is nearly parallel to c, another axis is parallel to b and the third susceptibility (usually the maximum) is close to a. The paramagnetic susceptibility has a disk-shaped magnitude ellipsoid with strong anisotropy ( P' < 2). The ferromagnetic contributions at low fields have more variably shaped ellipsoids with greater eccentricity ( P' < 5). The silicate lattice does not constrain their orientation. Our technique cannot determine the principal axes of the ferromagnetic component. However, its principal values usually correspond with the paramagnetic principal susceptibilities in order of magnitude. Thus, the combined paramagnetic-ferromagnetic anisotropy recognised in routine studies of AMS should faithfully represent the petrofabric of most micaceous rocks. Nevertheless, nearly 10% of our samples have incompatible anisotropy ellipsoids for the silicate host and magnetite inclusions. These yield a net inverse AMS that does not correctly represent the orientation of the silicate lattice. Therefore, some caution is necessary in petrofabric-AMS studies of micaceous rocks.

  9. Crystal chemistry of a Ba-dominant analogue of hydrodelhayelite and natural ion-exchange transformations in double- and triple-layer phyllosilicates in post-volcanic systems of the Eifel region, Germany

    NASA Astrophysics Data System (ADS)

    Zubkova, N. V.; Chukanov, N. V.; Pekov, I. V.; Turchkova, A. G.; Lykova, I. S.; Schüller, W.; Ternes, B.; Pushcharovsky, D. Yu.

    2016-12-01

    A Ba-dominant (Ba > K) analogue of hydrodelhayelite (BDAH) from Löhley (Eifel Mts., Rhineland-Palatinate, Germany) and Ba-enriched varieties of related double- and triple-layer phyllosilicates from Eifel are studied. The crystal structure of BDAH was solved by direct methods and refined to R = 0.0698 [1483 unique reflections with I > 2σ( I)]. It is orthorhombic, Pmmn, a = 23.9532(9), b = 7.0522(3), c = 6.6064(3) Å, V = 1115.97(8) Å3, Z = 2. The structure is based upon delhayelite-type double-layer tetrahedral blocks [(Al,Si)4Si12O34(OH,O)4] connected by chains of (Ca,Fe)-centered octahedra. Ba2+ and subordinate K+ occur at partially vacant sites in zeolitic channels within the tetrahedral blocks. The crystal-chemical formula of BDAH is: (Ba0.42K0.34□0.24)(Ca0.88Fe0.12)2(□0.90Mg0.10)2[Si6(Al0.5Si0.5)2O17(OH0.71O0.29)2]ṡ6H2O. The formation of BDAH and Ba-rich varieties of altered delhayelite/fivegite, günterblassite and hillesheimite is considered as a result of leaching of Na, Cl, F and, partially, K and Ca accompanied with hydration and the capture of Ba as a result of natural ion exchange. These minerals are structurally a "bridge" between single-layer phyllosilicates and zeolites having the open three-dimensional tetrahedral Al-Si-O frameworks.

  10. PyXRD v0.6.7: a free and open-source program to quantify disordered phyllosilicates using multi-specimen X-ray diffraction profile fitting

    NASA Astrophysics Data System (ADS)

    Dumon, M.; Van Ranst, E.

    2016-01-01

    This paper presents a free and open-source program called PyXRD (short for Python X-ray diffraction) to improve the quantification of complex, poly-phasic mixed-layer phyllosilicate assemblages. The validity of the program was checked by comparing its output with Sybilla v2.2.2, which shares the same mathematical formalism. The novelty of this program is the ab initio incorporation of the multi-specimen method, making it possible to share phases and (a selection of) their parameters across multiple specimens. PyXRD thus allows for modelling multiple specimens side by side, and this approach speeds up the manual refinement process significantly. To check the hypothesis that this multi-specimen set-up - as it effectively reduces the number of parameters and increases the number of observations - can also improve automatic parameter refinements, we calculated X-ray diffraction patterns for four theoretical mineral assemblages. These patterns were then used as input for one refinement employing the multi-specimen set-up and one employing the single-pattern set-ups. For all of the assemblages, PyXRD was able to reproduce or approximate the input parameters with the multi-specimen approach. Diverging solutions only occurred in single-pattern set-ups, which do not contain enough information to discern all minerals present (e.g. patterns of heated samples). Assuming a correct qualitative interpretation was made and a single pattern exists in which all phases are sufficiently discernible, the obtained results indicate a good quantification can often be obtained with just that pattern. However, these results from theoretical experiments cannot automatically be extrapolated to all real-life experiments. In any case, PyXRD has proven to be useful when X-ray diffraction patterns are modelled for complex mineral assemblages containing mixed-layer phyllosilicates with a multi-specimen approach.

  11. Hyperspectral surface materials map of quadrangles 2962 and 3062, Gawdezereh (615), Galachah (616), Chahar Burjak (609), and Khan Neshin (610) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Hoefen, Todd M.; Kokaly, Raymond F.; King, Trude V.V.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  12. Hyperspectral surface materials map of quadrangles 3668 and 3768, Baghlan (221), Taluqan (222), Imam Sahib (215), and Rustaq (216) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  13. Hyperspectral surface materials map of quadrangles 3666 and 3766, Balkh (219), Mazar-e Sharif (220), Qarqin (213), and Hazara Toghai (214) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  14. Hyperspectral surface materials map of quadrangle 3260, Dasht-e-Chah-e-Mazar (419) and Anar Darah (420) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  15. Hyperspectral surface materials map of quadrangles 3664 and 3764, Char Shengo (123), Shibirghan (124), Jalajin (117), and Kham-Ab (118) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  16. Hyperspectral surface materials map of quadrangles 3360 and 3460, Kawir-e Naizar (413), Kohe-Mahmudo-Esmailjan (414), Kol-e Namaksar (407), and Ghoriyan (408) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.; Livo, Keith E.; Johnson, Michaela R.; Giles, Stuart A.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan.Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines.The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  17. Thermal evaporation and condensation synthesis of metallic Zn layered polyhedral microparticles

    SciT

    Khan, Waheed S.; Cao, Chuanbao, E-mail: cbcao@bit.edu.cn; Usman, Zahid

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Zn polyhedral microparticles prepared by thermal evaporation and condensation route. Black-Right-Pointing-Pointer Vapour-solid process based growth model governs the formation of Zn microparticles. Black-Right-Pointing-Pointer A strong PL emission band is observed at 369 nm in UV region. Black-Right-Pointing-Pointer Radiative recombination of electrons in the s, p conduction band and the holes in the d bands causes this emission. -- Abstract: Metallic zinc layered polyhedral microparticles have been fabricated by thermal evaporation and condensation technique using zinc as precursor at 750 Degree-Sign C for 120 min and NH{sub 3} as a carrier gas. The zinc polyhedral microparticles with oblate sphericalmore » shape are observed to be 2-9 {mu}m in diameter along major axes and 1-7 {mu}m in thickness along minor axes. The structural, compositional and morphological characterizations were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapour-solid (VS) mechanism based growth model has been proposed for the formation of Zn microparticles. Room temperature photoluminescence (PL) emission spectrum of the product exhibited a strong emission band at 369 nm attributed to the radiative recombination of electrons in the s, p conduction band near Fermi surface and the holes in the d bands generated by the optical excitation.« less

  18. Hyperspectral surface materials map of quadrangles 2964, 2966, 3064, and 3066, Shah-Esmail (617), Reg-Alaqadari (618), Samandkhan-Karez (713), Laki-Bander (611), Jahangir-Naweran (612), and Sreh-Chena (707) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials

    Hoefen, Todd M.; Kokaly, Raymond F.; King, Trude V.V.; Livo, Keith E.; Giles, Stuart A.; Johnson, Michaela R.

    2013-01-01

    This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), the HyMap™ imaging spectrometer measured reflected sunlight in 128 channels, covering wavelengths between 0.4 and 2.5 μm. The data were georeferenced, atmospherically corrected and converted to apparent surface reflectance, empirically adjusted using ground-based reflectance measurements, and combined into a mosaic with 23-m pixel spacing. Variations in water vapor and dust content of the atmosphere, in solar angle, and in surface elevation complicated correction; therefore, some classification differences may be present between adjacent flight lines. The reflectance spectrum of each pixel of HyMap™ imaging spectrometer data was compared to the reference materials in a spectral library of minerals, vegetation, water, and other materials. Minerals occurring abundantly at the surface and those having unique spectral features were easily detected and discriminated, while minerals having slightly different compositions but similar spectral features were less easily discriminated; thus, some map classes consist of several minerals having similar spectra, such as “Epidote or chlorite.” A designation of “Not classified” was assigned to the pixel when there was no match with reference spectra.

  19. Removal of phosphorus by the core-shell bio-ceramic/Zn-layered double hydroxides (LDHs) composites for municipal wastewater treatment in constructed rapid infiltration system.

    PubMed

    Zhang, Xiangling; Guo, Lu; Huang, Hualing; Jiang, Yinghe; Li, Meng; Leng, Yujie

    2016-06-01

    Constructed rapid infiltration systems (CRIS) are a reasonable option for treating wastewater, owing to their simplicity, low cost and low energy consumption. Layered double hydroxides (LDHs), novel materials with high surface area and anion exchange capacity, faced the problem of the application in CRIS due to the powdered form. To overcome this shortcoming, Zn-LDHs (FeZn-LDHs, CoZn-LDHs, AlZn-LDHs) were prepared by co-precipitation method and in-situ coated on the surface of the natural bio-ceramic to synthesize the core-shell bio-ceramic/Zn-LDHs composites. Characterization by Scanning Electron Microscope (SEM) and X-ray Fluorescence Spectrometer (XRFS) indicated that the Zn-LDHs were successful loaded on the natural bio-ceramic. Column tests experiments indicated that the bio-ceramic/Zn-LDHs efficiently enhanced the removal performance of phosphorus. The efficiently removal rates of bio-ceramic/FeZn-LDHs were 71.58% for total phosphorous (TP), 74.91% for total dissolved phosphorous (TDP), 82.31% for soluble reactive phosphorous (SRP) and 67.58% for particulate phosphorus (PP). Compared with the natural bio-ceramic, the average removal rates were enhanced by 32.20% (TP), 41.33% (TDP), 49.06% (SRP) and 10.50% (PP), respectively. Adsorption data of phosphate were better described by the Freundlich model for the bio-ceramic/Zn-LDHs and natural bio-ceramic, except for the bio-ceramic/CoZn-LDHs. The maximum adsorption capacity of bio-ceramic/AlZn-LDHs (769.23 mg/kg) was 1.77 times of the natural bio-ceramic (434.78 mg/kg). The effective desorption of phosphate could achieve by using a mixed solution of 5 M NaCl + 0.1 M NaOH, it outperformed the natural bio-ceramic of 18.95% for FeZn-LDHs, 7.59% for CoZn-LDHs and 12.66% for AlZn-LDHs. The kinetic data of the bio-ceramic/Zn-LDHs were better described by the pseudo-second-order equation. Compared the removal amount of phosphate by the natural bio-ceramic, the physical effects were improved little, but the chemical effects were enhanced for 112.49% for FeZn-LDHs, 111.89% for CoZn-LDHs and 122.67% for AlZn-LDHs. Therefore, the way of coating Zn-LDHs on the bio-ceramic efficiently improved the chemical effects in phosphate removal, supporting that it can use as potential substrates for the removal of phosphorus in CRIS. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Competitive Sorption of CO2 and H2O in 2:1 Layer Phyllosilicates

    SciT

    Schaef, Herbert T.; Loring, John S.; Glezakou, Vassiliki Alexandra

    The salting out effect, where increasing the ionic strength of aqueous solutions decreases the solubility of dissolved gases is a well-known phenomenon. Less explored is the opposite process where an initially anhydrous system containing a volatile, relatively non-polar component and inorganic ions is systematically hydrated. Expandable clays such as montmorillonite are ideal systems for exploring this scenario as they have readily accessible exchange sites containing cations that can be systematically dehydrated or hydrated, from near anhydrous to almost bulk-like water conditions. This phenomenon has new significance with the simultaneous implementation of geological sequestration and secondary utilization of CO2 to bothmore » mitigate climate warming and enhance extraction of methane from hydrated clay-rich formations. Here, the partitioning of CO2 and H2O between Na-, Ca-, and Mg-exchanged montmorillonite and variably hydrated supercritical CO2 (scCO2) was investigated using in situ X-ray diffraction, infrared (IR)spectroscopic titrations, and quartz crystal microbalance (QCM) measurements. Density functional theory calculations provided mechanistic insights. Structural volumetric changes were correlated to quantified changes in sorbed H2O and CO2 concentrations as a function of %H2O saturated in scCO2. Intercalation of CO2 is favored at low H2O/CO2 ratios in the interlayer region, where CO2 can solvate the interlayer cation. As the clay becomes more hydrated and the H2O/CO2 ratio increases, H2O displaces CO2 from the solvation shell of the cation and CO2 tends to segregate. This transition decreases both the entropic and enthalpic driving force for CO2 intercalation, consistent with experimentally observed loss of intercalated CO2.« less

  1. Kulkeite, a new metamorphic phyllosilicate mineral: Ordered 1∶1 chlorite/talc mixed-layer

    NASA Astrophysics Data System (ADS)

    Schreyer, W.; Medenbach, O.; Abraham, K.; Gebert, W.; Müller, W. F.

    1982-09-01

    Kulkeite occurs as platy, colorless, porphyroblastic, single crystals up to 2 mm in size in a low-grade dolomite rock associated with a Triassic meta-evaporite series at Derrag, Tell Atlas, Algeria, It is associated with sodian aluminian talc, unusual chlorite polytypes, and both K and Na phlogopite. Kulkeite is optically biaxial, negative, n x=1.552, n y=1.5605, n z=1.5610, 2Vz=24° (obs.). Based on microprobe analysis the empirical formula is (Na0.38K0.01Ca0.01)(Mg8.02Al0.99)[Al1.43Si6.57O20](OH)10 with some variation in Na, Si, and tetrahedral Al. The crystals are monoclinic with a=5.319(1), b=9.195(2), c=23.897(10) Å, β=97° 1(3)'; Z=2; the calculated density is 2.70 g cm-3. The four strongest lines in the X-ray powder pattern are (d, I, hkl): 7.90, 100, 003; 1.533, 100, 060; 7.42, 80, 002; 3.38, 80, 007; the 001 reflection with 23.7 Å has intensity 10. Transmission electron microscopy confirms the nature of a regular 1∶1 mixed-layer, which consists of 14 Å chlorite (clinochlore) sheets alternating with sheets of one-layer (9.5 Å) talc characterized by the lattice substitution NaAl→Si just as in the talc occurring as a discrete mineral co-existing with kulkeite. Kulkeite is intergrown with lamellae of clinochlore that represent two-layer and five-layer (70 Å) polytypes with optical birefringence exceeding the normal value for clinochlore by a factor of 3. The origin of kulkeite is due to low-grade metamorphism with temperatures probably not exceeding 400° C. As the clinochlore lamellae and sodian aluminian talc are found in mutual contact, kulkeite seems to represent a metastable mineral at least during the latest phase of metamorphism. However, at an earlier stage, prior to clinochlore formation, kulkeite might have been stable, and the incorporation of Na and Al into its talc component could indeed be the decisive factor for the formation of the mixed-layer.

  2. Transmission Electron Microscope Observations of Phyllosilicate Development During Experimental Aqueous Alteration of Allende

    NASA Technical Reports Server (NTRS)

    Jones, C. L.; Brearley, A. J.

    2000-01-01

    Samples of Allende have been altered hydrothermally under oxidizing conditions at 200 C. TEM studies show that within 30 days evidence of replacement of matrix olivines by fine-grained serpentine is present and by 90 days complete alteration of many grains has occurred.

  3. Interference of 1:1 and 2:1 layered phyllosilicates as excipients with ranitidine.

    PubMed

    Li, Zhaohui; Fitzgerald, Nicole M; Albert, Zachary; Jiang, Wei-Teh

    2016-04-01

    As natural ingredients and excipients, kaolinite and talc were frequently studied for their interactions with drugs in pharmaceutical formulations. In this study, the uptake of ranitidine (RT) on these two minerals was studied under different physic-chemical conditions and the mechanism of RT uptake on these two minerals contrasted. Although the thermodynamic and kinetic RT uptake on these two minerals was similar and the RT uptake on both minerals were limited to the external surfaces only, drastic difference in RT uptake was found under different equilibrium solution pH and ionic strength conditions. As cation exchange process was strongly affected by solution pH and ionic strength, the RT uptake on kaolinite was dominated by cation exchange and electrostatic interactions, while the RT uptake on talc was more controlled by inter- and intra- molecular hydrogen bonding interactions. For kaolinite, the limiting factor for RT uptake was the specific surface area due to monolayer RT adsorption. In contract, multilayer RT uptake was found on talc surfaces. No matter which mechanism dominated RT uptake on these minerals, the interaction should not be neglected in pharmaceutical formulations should these minerals be used as additives and/or excipients. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. ELECTRON TRANSFER MECHANISM AT THE SOLID-LIQUID INTERFACE OF PHYLLOSILICATES

    EPA Science Inventory

    Interfacial electron transfer processes on clay minerals have significant impact in natural environments and geochemical systems. Nitrobenzene was used as molecular probes to study the electron transfer mechanism at the solid-water interfaces of Fe-containing phyllosicates. For...

  5. Widespread exposure of Noachian phyllosilicates in the Margaritifer region of Mars: Implications for paleohydrology and astrobiological detection

    NASA Astrophysics Data System (ADS)

    Thomas, Rebecca J.; Hynek, Brian M.; Osterloo, Mikki M.; Kierein-Young, Kathryn S.

    2017-03-01

    The best locations at which to detect evidence for early life on Mars are in materials formed in near-surface aqueous environments, particularly where this resulted in the deposition of minerals such as clays that are favorable to preservation of organics. The geological history of the Margaritifer region has resulted in exceptional potential to preserve such deposits and to render them discoverable. Due to its topographic setting at the interface between highlands and lowlands, Margaritifer was a major sink for water and sediments in the early, Noachian, period, potentially creating environments that were habitable and conducive to clay formation. Subsequently, during the Late Hesperian to Amazonian, the ancient surface was extensively disrupted in association with the formation of multiple chaos regions. This activity had the potential to expose any astrobiological evidence from the earlier period. We used orbital image, spectral and topographic data to investigate the extent and means of exposure of Noachian clay-bearing deposits across the region. We find that they are indeed exposed over a very wide area in Margaritifer and that their mineralogy is most consistent with clay formation in a low-energy near-neutral pH groundwater environment. We additionally find that evidence for subsequent acidic groundwater activity is absent, indicating that biosignature preservation in these units is favored, perhaps to a greater degree than for similar deposits in the surrounding region. Further, due to the intense Hesperian-Amazonian geologic activity here, early clay-bearing units are exposed to a greater degree than achievable in regions with more localized erosive mechanisms.

  6. Specific Features of Profile Distribution and Crystallochemistry of Phyllosilicates in Soils of the Cisbaikal Forest-Steppe

    NASA Astrophysics Data System (ADS)

    Chizhikova, N. P.; Gamzikov, G. P.; Chechetko, E. S.

    2018-01-01

    The mineralogical composition of agrogray, dark gray, and agro-dark gray soils (Luvic Greyzemic Retic Phaeozems); agro-dark gray residual-calcareous soils (Calcaric Cambic Phaeozems); clay-illuvial agrochernozems (Luvic Chernic Phaeozems); and agrochernozems with migrational-mycelial carbonates (Haplic Chernozems) developed in the forest-steppe of Central Siberia within the Irkutsk Depression has been studied. The clay (<1 μm) fraction separated from these soils consists of mixed-layer minerals with alternating layers of hydromica, smectite, vermiculite, and chlorite; the proportions between them change within the soil profiles. The clay fraction also contains hydromicas, kaolinite, chlorite, and some admixture of the fine-dispersed quartz. Each type of the soils is characterized by its own distribution pattern of clay material with specific alternation of layers in the mixed-layer formations. Mixed-layer minerals of the chlorite-vermiculite type predominate in the upper horizons of texture-differentiated soils. Down the soil profile, the content of mixed-layer mica-smectitic minerals increases. In the clay fraction of arable dark gray-humus soils with residual carbonates, the distribution of the clay fraction and major mineral phases in the soil profile is relatively even. An increased content of well-crystallized kaolinite is typical of these soils. The parent material of agrochernozems has a layered character: the upper horizons are generally depleted of clay, and the middle-profile and lower horizons are characterized by the considerable kaolinite content. In general, the clay material of soils of the Tulun-Irkutsk forest-steppe differs considerably from the clay material of foreststeppe soils developed from loesslike and mantle loams in the European part of Russia. In particular, this difference is seen in the proportions between major mineral phases and between biotitic and muscovitic components, as well as in the degree of crystallinity and behavior of kaolinite and chlorite.

  7. Intriguing Dehydrated Phyllosilicates Found in an Unusual Clast in the LL3.15 Chondrite NWS6925

    NASA Technical Reports Server (NTRS)

    Johnson, Jessica M.; Zolensky, Michael E.; Chan, Queenie; Kring, David A.

    2016-01-01

    Meteorites provide us with valuable insights into the conditions of the early solar system. Collisions often occur in our solar system that can result in materials accreting to other bodies as foreign clasts. These foreign pieces may have multiple origins that can sometimes be easily identified as a particular type of meteorite. It is important to interpret the origins of these clasts in order to understand dynamics of the solar system, especially throughout its early history. The Nice Model, as modified, proposes a reordering of planetary orbits that is hypothesized to have triggered the Late Heavy Bombardment. Clasts found within meteorites that came from objects in the solar system not commonly associated as an impactor could be indicative of such an event suggested by the Nice Model. Impacts also redistribute material from one region of an asteroid to another, and so clasts are found that reveal portions of the geological history of a body that are not recorded by typical samples. These would be cognate clasts. The goal of this investigation was to examine meteorites that had particularly interesting foreign and cognate clasts enclosed in them. We focus here on an unusual clast located in the ordinary chondrite, NWA 6925. This is one of three clasts analyzed during the LPI summer internship of Jessica Johnson.

  8. Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals

    NASA Astrophysics Data System (ADS)

    Oerter, Erik; Finstad, Kari; Schaefer, Justin; Goldsmith, Gregory R.; Dawson, Todd; Amundson, Ronald

    2014-07-01

    In isotope-enabled hydrology, soil and vadose zone sediments have been generally considered to be isotopically inert with respect to the water they host. This is inconsistent with knowledge that clay particles possessing an electronegative surface charge and resulting cation exchange capacity (CEC) interact with a wide range of solutes which, in the absence of clays, have been shown to exhibit δ18O isotope effects that vary in relation to the ionic strength of the solutions. To investigate the isotope effects caused by high CEC clays in mineral-water systems, we created a series of monominerallic-water mixtures at gravimetric water contents ranging from 5% to 32%, consisting of pure deionized water of known isotopic composition with homoionic (Mg, Ca, Na, K) montmorillonite. Similar mixtures were also created with quartz to determine the isotope effect of non-, or very minimally-, charged mineral surfaces. The δ18O value of the water in these monominerallic soil analogs was then measured by isotope ratio mass spectrometry (IRMS) after direct headspace CO2 equilibration. Mg- and Ca-exchanged homoionic montmorillonite depleted measured δ18O values up to 1.55‰ relative to pure water at 5% water content, declining to 0.49‰ depletion at 30% water content. K-montmorillonite enriched measured δ18O values up to 0.86‰ at 5% water content, declining to 0.11‰ enrichment at 30% water. Na-montmorillonite produces no measureable isotope effect. The isotope effects observed in these experiments may be present in natural, high-clay soils and sediments. These findings have relevance to the interpretation of results of direct CO2-water equilibration approaches to the measurement of the δ18O value of soil water. The adsorbed cation isotope effect may bear consideration in studies of pedogenic carbonate, plant-soil water use and soil-atmosphere interaction. Finally, the observed isotope effects may prove useful as molecular scale probes of the nature of mineral-water interactions.

  9. Zinc speciation in mining and smelter contaminated overbank sediments by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Van Damme, An; Degryse, Fien; Smolders, Erik; Sarret, Géraldine; Dewit, Julie; Swennen, Rudy; Manceau, Alain

    2010-07-01

    Overbank sediments contaminated with metalliferous minerals are a source of toxic metals that pose risks to living organisms. The overbank sediments from the Geul river in Belgium contain 4000-69,000 mg/kg Zn as a result of mining and smelting activities, principally during the 19th century. Three main Zn species were identified by powder Zn K-edge EXAFS spectroscopy: smithsonite (ZnCO 3), tetrahedrally coordinated sorbed Zn (sorbed IVZn) and Zn-containing trioctahedral phyllosilicate. Smithsonite is a primary mineral, which accounts for approximately 20-60% of the Zn in sediments affected by mining and smelting of oxidized Zn ores (mostly carbonates and silicates). This species is almost absent in sediments affected by mining and smelting of both sulphidic (ZnS, PbS) and oxidized ores, presumably because of acidic dissolution associated with the oxidation of sulphides, as suggested by the lower pH of this second type of sediment (pH(CaCl 2) <7.0 vs. pH(CaCl 2) >7.0 for the first type). Thus, sulphide minerals in sediment deposits can act as a secondary source of dissolved metals by a chemical process analogous to acid mine drainage. The sorbed IVZn component ranges up to approximately 30%, with the highest proportion occurring at pH(CaCl 2) <7.0 as a result of the readsorption of dissolved Zn 2+ on sediments constituents. Kerolite-like Zn-rich phyllosilicate is the major secondary species in all samples, and in some the only detected species, thus providing the first evidence for pervasive sequestration of Zn into this newly formed precipitate at the field scale.

  10. HRTEM and EFTEM Studies of Phyllosilicate-Organic Matter Associations in Matrix and Dark Inclusions in the EET92042 CR2 Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Abreu, Neyda M.; Brearley, Adrian J.

    2005-01-01

    Based on petrologic and isotopic observations, the CR chondrites represent one of the most primitive carbonaceous chondrite groups. The organic matter in CR chondrite matrices is considered to be among the most ancient carbonaceous matter known, potentially providing a link between organic matter in the interstellar medium and our solar system [1]. However, the organic chemistry of CR chondrites may be complicated by the fact that these meteorites have undergone moderate secondary alteration, which potentially overprints primordial features [2]. Although the general effects of this alteration have been documented [2], the details of the fine-grained mineralogy and alteration styles of CR matrices are not fully understood. Here we present TEM observations of matrix in EET 92042, a CR chondrite that contains particularly primitive insoluble organic matter [1]. Preliminary studies [3] determined that EET 92042 matrix is heterogeneous in terms of mineralogy, texture, and petrographic fabric on the micron scale. EET 92042 contains magnetite-rich regions, foliated matrix and dark inclusions (DIs). Some chondrules show fine-grained rims, similar to those described by [4].

  11. Changes in zinc speciation with mine tailings acidification in a semiarid weathering environment.

    PubMed

    Hayes, Sarah M; O'Day, Peggy A; Webb, Sam M; Maier, Raina M; Chorover, Jon

    2011-09-01

    High concentrations of residual metal contaminants in mine tailings can be transported easily by wind and water, particularly when tailings remain unvegetated for decades following mining cessation, as is the case in semiarid landscapes. Understanding the speciation and mobility of contaminant metal(loid)s, particularly in surficial tailings, is essential to controlling their phytotoxicities and to revegetating impacted sites. In prior work, we showed that surficial tailings samples from the Klondyke State Superfund Site (AZ, USA), ranging in pH from 5.4 to 2.6, represent a weathering series, with acidification resulting from sulfide mineral oxidation, long-term Fe hydrolysis, and a concurrent decrease in total (6000 to 450 mg kg(-1)) and plant-available (590 to 75 mg kg(-1)) Zn due to leaching losses and changes in Zn speciation. Here, we used bulk and microfocused Zn K-edge X-ray absorption spectroscopy (XAS) data and a six-step sequential extraction procedure to determine tailings solid phase Zn speciation. Bulk sample spectra were fit by linear combination using three references: Zn-rich phyllosilicate (Zn(0.8)talc), Zn sorbed to ferrihydrite (Zn(adsFeOx)), and zinc sulfate (ZnSO(4) · 7H(2)O). Analyses indicate that Zn sorbed in tetrahedral coordination to poorly crystalline Fe and Mn (oxyhydr)oxides decreases with acidification in the weathering sequence, whereas octahedral zinc in sulfate minerals and crystalline Fe oxides undergoes a relative accumulation. Microscale analyses identified hetaerolite (ZnMn(2)O(4)), hemimorphite (Zn(4)Si(2)O(7)(OH)(2) · H(2)O) and sphalerite (ZnS) as minor phases. Bulk and microfocused spectroscopy complement the chemical extraction results and highlight the importance of using a multimethod approach to interrogate complex tailings systems.

  12. Changes in zinc speciation with mine tailings acidification in a semi-arid weathering environment

    PubMed Central

    Hayes, Sarah M.; O’Day, Peggy A.; Webb, Sam M.; Maier, Raina M.; Chorover, Jon

    2011-01-01

    High concentrations of residual metal contaminants in mine tailings can be transported easily by wind and water, particularly when tailings remain unvegetated for decades following mining cessation, as is the case in semi-arid landscapes. Understanding the speciation and mobility of contaminant metal(loid)s, particularly in surficial tailings, is essential to controlling their phytotoxicities and to revegetating impacted sites. In prior work, we showed that surficial tailings samples from the Klondyke State Superfund Site (AZ, USA), ranging in pH from 5.4 to 2.6, represent a weathering series, with acidification resulting from sulfide mineral oxidation, long-term Fe hydrolysis, and a concurrent decrease in total (6,000 to 450 mg kg−1) and plant-available (590 to 75 mg kg−1) Zn due to leaching losses and changes in Zn speciation. Here, we used bulk and micro-focused Zn K-edge X-ray absorption spectroscopy (XAS) data and a six-step sequential extraction procedure to determine tailings solid phase Zn speciation. Bulk sample spectra were fit by linear combination using three references: Zn-rich phyllosilicate (Zn0.8talc), Zn sorbed to ferrihydrite (ZnadsFeOx), and zinc sulfate (ZnSO4·7H2O). Analyses indicate that Zn sorbed in tetrahedral coordination to poorly-crystalline Fe and Mn (oxyhydr)oxides decreases with acidification in the weathering sequence, whereas octahedral zinc in sulfate minerals and crystalline Fe oxides undergoes a relative accumulation. Micro-scale analyses identified hetaerolite (ZnMn2O4), hemimorphite (Zn4Si2O7(OH)2·H2O) and sphalerite (ZnS) as minor phases. Bulk and micro-focused spectroscopy complement the chemical extraction results and highlight the importance of using a multi-method approach to interrogate complex tailings systems. PMID:21761897

  13. Apports des phyllosilicates dans la différenciation entre altération hypogène et altération supergène dans le basalte triasique du Moyen Atlas (Maroc)Contribution of phyllosilicates to distinguish between hypogene alteration and weathering in Triassic basalt from Middle Atlas (Morocco)

    NASA Astrophysics Data System (ADS)

    Dekayir, Abdelilah; Danot, Michel; Allali, Nabil

    2002-09-01

    Triassic basalt of the Middle Atlas has been subject to metamorphic transformation then weathering. Occurrence in both metabasalt and saprolite of ubiquitous clay minerals, such as smectite and mixed layers chlorite-smectite, makes it difficult to distinguish between the two alteration facies and explains the interest of complementary sources of information. In the Bhallil weathering profile, petrographical and mineralogical analyses of primary igneous minerals and their alteration products coupled with Fe oxidation state determination in clay fractions allow to identify three alteration facies: ( i) metamorphic basalt, where iron occurs mainly as the ferrous form; ( ii) the lower part of saprolite, where iron is partially oxidized to its ferric form; ( iii) the upper part of saprolite, where iron is completely oxidized. To cite this article: A. Dekayir et al., C. R. Geoscience 334 (2002) 877-884.

  14. R Raman Spectroscopy and Petrology of Antarctic CR Chondrites: Comparison with Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2015-01-01

    In Renazzo-like carbonaceous (CR) chondrites, abundant original Fe,Ni-metal is preserved in chrondules, but the matrix is characterized by fine-grained magnetite with phyllosilicate. This combination of reduced Fe in chrodrules with oxidized Fe and phyllosilicate in the matrix has been attributed to aqueous alteration of matrix at relatively low temperatures.

  15. HRTEM/AEM and SEM study of fluid-rock interactions: Interaction of copper, silver, selenium, chromium, and cadmium-bearing solutions with geological materials at near surface conditions, with an emphasis on phyllosilicates. Progress report, September 1, 1992--September 1, 1993

    SciT

    Veblen, D.R.; Ilton, E.S.

    1993-05-01

    TEM of naturally occurring Cu-rich biotites and feldspars from weathered portions of porphyry copper deposits has shown that copper is not in the structure of these minerals, is present in their weathering products such as copper-rich vermiculite layers, submicroscopic iron oxyhydroxides and native copper inclusions, and chrysocoua. Reaction of acidic solutions bearing-Cu{sup 2+}, Ag{sup +}, Cr{sup 6+}, and Se{sup 4+}, at 25C, with biotite indicates that ferrous iron in biotite can reduce Cu{sup 2+}, Ag+, and Cr{sup 6+} to Cu{degrees}, Ag{degrees}, and Cr(III), respectively. However, Se{sup 4+} does not appear to be reduced. Copper is reduced in the interlayer region,more » silver is reduced in the interlayer and on the biotite surfaces, and chromium is reduced at the biotite surface. TEM shows that the reduction of copper and silver by biotite can produce native metal inclusions, whereas reduction of Cr(VI) to CR(III) did not produce any Cr-bearing precipitates. The copper and silver experiments show that iron in biotite can be a much stronger reducing agent than iron in solution. TEM and XPS of biotites reacted with CR(VI) clearly show that edges or (hkO) faces are much more reactive than the basal planes, where the edges are strongly enriched in CR(III) relative to the basal planes. In contrast, biotites reacted with Cr(IH)-bearing solutions show little fractionation between the edges and basal planes. Another important result of our XPS studies is that we demonstrated that the oxidation state of near surface iron in biotite can be quantified.« less

  16. Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument

    Mustard, J.F.; Murchie, S.L.; Pelkey, S.M.; Ehlmann, B.L.; Milliken, R.E.; Grant, J. A.; Bibring, J.-P.; Poulet, F.; Bishop, J.; Dobrea, E.N.; Roach, L.; Seelos, F.; Arvidson, R. E.; Wiseman, S.; Green, R.; Hash, C.; Humm, D.; Malaret, E.; McGovern, J.A.; Seelos, K.; Clancy, T.; Clark, R.; des Marais, D.; Izenberg, N.; Knudson, A.; Langevin, Y.; Martin, T.; McGuire, P.; Morris, Robert; Robinson, M.; Roush, T.; Smith, M.; Swayze, G.; Taylor, H.; Titus, T.; Wolff, M.

    2008-01-01

    Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L’Eau, les Glaces et l’Activitié) instrument1,2, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity3) were specific to surface environments during the earliest era of Mars’s history4. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)4 of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

  17. Sulfate Formation From Acid-Weathered Phylosilicates: Implications for the Aqueous History of Mars

    NASA Technical Reports Server (NTRS)

    Craig, P. I.; Ming, D. W.; Rampe, E. B.

    2014-01-01

    Most phyllosilicates on Mars are thought to have formed during the planet's earliest Noachian era, then Mars underwent a global change making the planet's surface more acidic [e.g. 1]. Prevailing acidic conditions may have affected the already existing phyllosilicates, resulting in the formation of sulfates. Both sulfates and phyllosilicates have been identified on Mars in a variety of geologic settings [2] but only in a handful of sites are these minerals found in close spatial proximity to each other, including Mawrth Vallis [3,4] and Gale Crater [5]. While sulfate formation from the acidic weathering of basalts is well documented in the literature [6,7], few experimental studies investigate sulfate formation from acid-weathered phyllosilicates [8-10]. The purpose of this study is to characterize the al-teration products of acid-weathered phyllosilicates in laboratory experiments. We focus on three commonly identified phyllosilicates on Mars: nontronite (Fe-smectite), saponite (Mg-smectite), and montmorillonite (Al-smectite) [1, and references therein]. This information will help constrain the formation processes of sulfates observed in close association with phyllosilicates on Mars and provide a better understanding of the aqueous history of such regions as well as the planet as a whole.

  18. Testing Cadmium-Free Coatings

    DTIC Science & Technology

    2011-08-30

    Chromium (Cr6+) None Zinc Cr6+ None Zinc Trivalent Chromium Process (TCP) Enseal C22 Zinc Nickel TCP Enseal C22 High Purity Al TCP Enseal C22 Zn-rich two...Secretary of Defense Directive • “Approve the use of alternatives [to hexavalent chromium (Cr6+)] where they can perform adequately for the intended

  19. More Evidence of the Importance of Amorphous Silicates in CM Carbonaceous Chondrites: New Observations from a Fine-Grained Rim in the CM2 Chondrite, TIL 91722

    NASA Astrophysics Data System (ADS)

    Brearley, A. J.; Le Guillou, C.

    2015-07-01

    A fine-grained rim in TIL 91722 contains abundant amorphous silicate material containing nanophase sulfides. Phyllosilicates are rare. The amorphous material has a high ferric iron content indicative of oxidation coupled with hydration.

  20. The origin of alteration "orangettes" in Dhofar 019: Implications for the age and aqueous history of the shergottites

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Kemppinen, L.; Lee, M. R.; Taylor, L. A.

    2017-12-01

    The shergottites are the largest group of Martian meteorites, and the only group that has not been found to contain definitive evidence of Martian aqueous alteration. Given recent reports of current liquid water at the surface of Mars, this study aimed to investigate in detail the possibility of Martian phyllosilicate within shergottite Dhofar 019. Optical and scanning electron microscopy, followed by transmission electron microscopy, confirmed the presence of alteration orangettes, with a layered structure consisting of poorly ordered Mg-phyllosilicate and calcite. These investigations identified maskelynite dissolution, followed by Mg-phyllosilicate and calcite deposition within the dissolution pits, as the method of orangette production. The presence of celestine within the orangette layers, the absence of shock dislocation features within calcite, and the Mg-rich nature of the phyllosilicate, all indicate a terrestrial origin for these features on Dhofar 019.

  1. Terrestrial Clay under Microscope

    2008-09-30

    A scanning electron microscope captured this image of terresterial soil containing a phyllosilicate mineral from Koua Bocca, Ivory Coast, West Africa. This soil shares some similarities with Martian soil scooped by NASA Phoenix Lander.

  2. Clay minerals in primitive meteorites and interplanetary dust 1

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Keller, L. P.

    1991-01-01

    Many meteorites and interplanetary dust particles (IDPs) with primitive compositions contain significant amounts of phyllosilicate minerals, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period of the solar system. These meteorites are chondrites (near solar composition) of the carbonaceous and ordinary varieties. The former are subdivided (according to bulk composition and petrology) into CI, CM, CV, CO, CR, and ungrouped classes. IDPs are extraterrestrial particulates, collected in stratosphere, which have chemical compositions indicative of a primitive origin; they are typically distinct from the primitive meteorites. Characterization of phyllosilicates in these materials is a high priority because of the important physico-chemical information they hold. The most common phyllosilicates present in chondritic extraterrestrial materials are serpentine-group minerals, smectites, and micas. We discuss these phyllosilicates and describe the interpretation of their occurrence in meteorites and IDPs and what this indicates about history of their parent bodies, which are probably the hydrous asteroids.

  3. SciT

    Wu, T.; Griffin, A. M.; Gorski, C. A.

    Dissimilatory microbial reduction of solid-phase Fe(III)-oxides and Fe(III)-bearing phyllosilicates (Fe(III)-phyllosilicates) is an important process in anoxic soils, sediments, and subsurface materials. Although various studies have documented the relative extent of microbial reduction of single-phase Fe(III)-oxides and Fe(III)-phyllosilicates, detailed information is not available on interaction between these two processes in situations where both phases are available for microbial reduction. The goal of this research was to use the model dissimilatory iron-reducing bacterium (DIRB) Geobacter sulfurreducens to study Fe(III)-oxide vs. Fe(III)-phyllosilicate reduction in a range of subsurface materials and Fe(III)-oxide stripped versions of the materials. Low temperature (12K) Mossbauer spectroscopy was usedmore » to infer changes in the relative abundances of Fe(III)-oxide, Fe(III)-phyllosilicate, and phyllosilicate-associated Fe(II) (Fe(II)-phyllosilicate). A Fe partitioning model was employed to analyze the fate of Fe(II) and assess the potential for abiotic Fe(II)-catalyzed reduction of Fe(III)-phyllosilicates. The results showed that in most cases Fe(III)- oxide utilization dominated (70-100 %) bulk Fe(III) reduction activity, and that electron transfer from oxide-derived Fe(II) played only a minor role (ca. 10-20 %) in Fe partitioning. In addition, the extent of Fe(III)-oxide reduction was positively correlated to surface area-normalized cation exchange capacity and the phyllosilicate-Fe(III)/total Fe(III) ratio, which suggests that the phyllosilicates in the natural sediments promoted Fe(III)-oxide reduction by binding of oxide-derived Fe(II), thereby enhancing Fe(III)-oxide reduction by reducing or delaying the inhibitory effect that Fe(II) accumulation on oxide and DIRB cell surfaces has on Fe(III)-oxide reduction. In general our results suggest that although Fe(III)-oxide reduction is likely to dominate bulk Fe(III) reduction in most subsurface

  4. Spectral analysis of crater central peak material (ccp)

    NASA Astrophysics Data System (ADS)

    Galiano, A.; Palomba, E.; Longobardo, A.; De Sanctis, M. C.; Raponi, A.; Tosi, F.; Ammannito, E.; Raymond, C. A.; Russell, C. T.

    2017-09-01

    We spectrally investigated 32 ccp units, which stand out in geologic maps of Ceres as they exhibit a different color and morphology with respect to the surrounding floor. We focus our attention on spectral parameters related to Mg-phyllosilicates (2.7 μm band), ammoniated phyllosilicates (3.1 μm band) and carbonates (bands at about 3.4 and 4.0 μm).

  5. Mineralogy of an unusual CM clast in the Kaidun meteorite

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Ivanov, A. V.; Yang, S. V.; Barrett, R. A.; Browning, L.

    1994-01-01

    Kaidun is breccia of disparate enstatite and carbonaceous chondrite clasts, and continues to provide real surprises. Many Daidun clasts have been intensely altered by an aqueous fluid, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and presence of carbonate- and phyllosilicate-filled veins. In this report we describe an unusual CM lithology containing beautiful aggregates of jackstraw pyrrhotites, not previously reported from any meteorite.

  6. Aqueous mineralogy and stratigraphy at and around the proposed Mawrth Vallis MSL Landing Site: New insights into the aqueous history of the region

    Dobrea, Eldar Z. Noe; Michalski, Joseph; Swayze, Gregg

    2011-01-01

    In this work, we have confirmed the mineralogical stratigraphy previously inferred by other authors, but also demonstrate the presence of additional minerals, including a possible acid-leaching product near the top of the sequence, an Mh-OH bearing phyllosilicate at the to of the sequence, and potentially a Ca-sulfate at the bottom of the phyllosilicate sequence. The latter has important implications regarding the relative timing of sulfate vs clay formation on Mars.

  7. Photoluminescence spectra of n-ZnO/p-GaN:(Er + Zn) and p-AlGaN:(Er + Zn) heterostructures

    SciT

    Mezdrogina, M. M., E-mail: margaret.m@mail.ioffe.ru; Krivolapchuk, V. V., E-mail: vlad.krivol@mail.ioffe.ru; Feoktistov, N. A.

    2008-07-15

    Luminescence intensity of heterostructures based on n-ZnO/p-GaN:(Er + Zn) and n-ZnO/AlGaN:(Er + Zn) is higher by more than an order of magnitude than the corresponding intensity of separate n-ZnO, p-GaN:(Er + Zn), and AlGaN:(Er + Zn) layers. Most likely, this phenomenon is due to the effective tunneling recombination of charge carriers caused by a decrease in the concentration of the nonradiative recombination centers located between the n-ZnO/p-GaN:(Er + Zn) and n-ZnO/AlGaN:(Er + Zn) layers.

  8. Assessing Spectral Evidence of Aqueous Activity in Two Putative Martian Paleolakes

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Marzo, Giuseppe A.; Fonti, Sergio; Orofino, Vicenzo; Blanco, Armando; Gross, Christoph; Wendt, Lorenz

    2011-01-01

    We evaluate the evidence for the presence of mineral spectral signatures indicative of the past presence of water at two putative paleolakes on Mars using observations by the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Image Spectrometer for Mars (CRISM). CRISM spectra of both sites are consistent with laboratory spectra of Mg-rich phyllosilicates. Our analysis represents the first detailed evaluation of these locations. The spatial occurrence and association with topographic features within the craters is distinctly different for the two sites. The occurrence of these minerals supports the conclusion that water was once active in the areas sampled by these craters. The distribution of the phyllosilicates in Luqa does not provide distinctive evidence for the presence of a previous standing body of water and is consistent with either impact emplacement or post-impact alteration. For Cankuzo, the phyllosilicate distribution provides evidence of a layer in the crater wall indicative of aqueous activity, but does not require a paleolake.

  9. In-situ micro-FTIR Study of Thermal Changes of Organics in Tagish Lake Meteorite: Behavior of Aliphatic Oxygenated Functions and Effects of Minerals

    NASA Technical Reports Server (NTRS)

    Kebukawa, Yoko; Nakashima, Satoru; Nakamura-Messenger, Keiko; Zolensky, Michael E.

    2007-01-01

    Systematic in-situ FTIR heating experiments of Tagish Lake meteorite grains have been performed in order to study thermal stability of chondritic organics. Some aliphatic model organic substances have also been used to elucidate effects of hydrous phyllosilicate minerals on the thermal stability of organics. The experimental results indicated that organic matter in the Tagish Lake meteorite might contain oxygenated aliphatic hydrocarbons which are thermally stable carbonyls such as ester and/or C=O in ring compounds. The presence of hydrous phyllosilicate minerals has a pronounced effect on the increase of the thermal stability of aliphatic and oxygenated functions. These oxygenated aliphatic organics in Tagish Lake can be formed during the aqueous alteration in the parent body and the formation temperature condition might be less than 200 C, based especially on the thermal stability of C-O components. The hydrous phyllosilicates might provide sites for organic globule formation and protected some organic decomposition

  10. Thermal Emission Spectroscopy of 1 Ceres: Evidence for Olivine

    NASA Technical Reports Server (NTRS)

    Witteborn, Fred. C.; Roush, Ted L.; Cohen, Martin

    1999-01-01

    Thermal emission spectra of the largest asteroid, 1 Ceres, obtained from the Kuiper Airborne Observatory display features that may provide information about its surface mineralogy. The emissivity, obtained by dividing the spectra by a standard thermal model, is compared with emissivity spectra of olivines and phyllosilicates deduced via Kirchoff's law from reflectivity measurements. The spectra provide a fairly good match to fine grained olivines (0 to 5 micrometer size range). The smoothness of the spectrum beyond 18 micrometers is an indication of particles smaller than 50 micrometers. While the abrupt rise in emissivity near 8 micrometers matches many silicates, the distinct emissivity minimum centered near 12.8 micrometers is consistant with iron-poor olivines, but not with phyllosilicates. It suggests the presence of opaques and does not exclude a mixture with organics and fine-grained phyllosilicates.

  11. CLAYFORM: a FORTRAN 77 computer program apportioning the constituents in the chemical analysis of a clay or other silicate mineral into a structural formula

    Bodine, M.W.

    1987-01-01

    The FORTRAN 77 computer program CLAYFORM apportions the constituents of a conventional chemical analysis of a silicate mineral into a user-selected structure formula. If requested, such as for a clay mineral or other phyllosilicate, the program distributes the structural formula components into appropriate default or user-specified structural sites (tetrahedral, octahedral, interlayer, hydroxyl, and molecular water sites), and for phyllosilicates calculates the layer (tetrahedral, octahedral, and interlayer) charge distribution. The program also creates data files of entered analyses for subsequent reuse. ?? 1987.

  12. Detection of hydrated silicates in crustal outcrops in the northern plains of Mars.

    PubMed

    Carter, J; Poulet, F; Bibring, J-P; Murchie, S

    2010-06-25

    The composition of the ancient martian crust is a key ingredient in deciphering the environment and evolution of early Mars. We present an analysis of the composition of large craters in the martian northern plains based on data from spaceborne imaging spectrometers. Nine of the craters have excavated assemblages of phyllosilicates from ancient, Noachian crust buried beneath the plains' cover. The phyllosilicates are indistinguishable from those exposed in widespread locations in the southern highlands, demonstrating that liquid water once altered both hemispheres of Mars.

  13. SciT

    Wu, Tao; Kukkadapu, Ravi K.; Griffin, Aron M.

    Fe(III)-oxides and Fe(III)-bearing phyllosilicates are the two major iron sources utilized as electron acceptors by dissimilatory iron-reducing bacteria (DIRB) in anoxic soils and sediments. Although there have been many studies of microbial Fe(III)-oxide and Fe(III)-phyllosilicate reduction with both natural and specimen materials, no controlled experimental information is available on the interaction between these two phases when both are available for microbial reduction. In this study, the model DIRB Geobacter sulfurreducens was used to examine the pathways of Fe(III) reduction in Fe(III)-oxide stripped subsurface sediment that was coated with different amounts of synthetic high surface area goethite. Cryogenic (12K) 57Fe Mössbauermore » spectroscopy was used to determine changes in the relative abundances of Fe(III)-oxide, Fe(III)-phyllosilicate, and phyllosilicate-associated Fe(II) (Fe(II)-phyllosilicate) in bioreduced samples. Analogous Mössbauer analyses were performed on samples from abiotic Fe(II) sorption experiments in which sediments were exposed to a quantity of exogenous soluble Fe(II) (FeCl22H2O) comparable to the amount of Fe(II) produced during microbial reduction. A Fe partitioning model was developed to analyze the fate of Fe(II) and assess the potential for abiotic Fe(II)-catalyzed reduction of Fe(III)-phyllosilicatesilicates. The microbial reduction experiments indicated that although reduction of Fe(III)-oxide accounted for virtually all of the observed bulk Fe(III) reduction activity, there was no significant abiotic electron transfer between oxide-derived Fe(II) and Fe(III)-phyllosilicatesilicates, with 26-87% of biogenic Fe(II) appearing as sorbed Fe(II) in the Fe(II)-phyllosilicate pool. In contrast, the abiotic Fe(II) sorption experiments showed that 41 and 24% of the added Fe(II) engaged in electron transfer to Fe(III)-phyllosilicate surfaces in synthetic goethite-coated and uncoated sediment. Differences in the rate of Fe

  14. Smectites on Cape York, Matijevic Hill, Mars, Observed and Characterized by Crism and Opportunity

    NASA Technical Reports Server (NTRS)

    Arvidson, R.; Bennett, K.; Catalano, J.; Fraeman, A.; Gellert, R.; Guinness, E.; Morris, R.; Murchie, S.; Smith, M.; Squyres, S.; hide

    2013-01-01

    Opportunity has conducted an extensive "walk-about" and set of in-situ measurements on strata exposed on the inboard side of Cape York, a segment of the dissected rim of the Noachian-age approx.22 km wide Endeavour crater [1] (Fig. 1). The specific region for the observations (Matijevic Hill) was chosen based on along track oversampled (ATO) CRISM hyperspectral observations (processed to 5 m/pixel) that showed the presence of exposures of Fe/Mg smectite phyllosilicates. We describe the first ground-based observations of phyllosilicates on Mars and discuss implications based on the combined CRISM and Opportunity measurements.

  15. Experimentally Shocked and Altered Basalt: VNIR Spectra of Mars Analog Materials

    NASA Technical Reports Server (NTRS)

    Bell, M. S.

    2017-01-01

    Major occurrences of hydrous alteration minerals on Mars have been found in Noachian impact craters formed in basaltic targets and detected using visible/near infrared (VNIR) spectroscopy. Until recently phyllosilicates were detected only in craters in the southern hemisphere. However, it has been reported that at least nine craters in the northern plains apparently excavated thick layers of lava and sediment to expose phyllosilicates as well and two Hesperian-aged impact craters, Toro and Majuro, bear evidence of phyllosilicates in the southern highlands. Turner et al. 2015 reported that hydrated minerals were identified in three Amazonian aged complex impact craters, located at 52.42degN, 39.86degE in the Ismenius Lacus quadrangle, at 8.93degN, 141.28degE in Elysium, and within Stokes crater. These discoveries indicate that Mars was globally altered by water throughout its past but do not fully constrain formation conditions for phyllosilicate occurrences which have important implications for the evolution of the surface and biological potential of Mars.

  16. Iron alteration minerals in the visible and near-infrared spectra of low-albedo asteroids

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Jarvis, Kandy S.; Gaffey, Michael J.

    1994-01-01

    Absorption features centered near 0.60-0.65 and 0.80-0.90 micrometers have been identified in the spectra of five low-albedo main-belt and outer-belt asteroids. These absorption features are attributed respectively to the (6)A(sub 1) goes to (4)T(sub 2)(G) and (6)A(sub 1) goes to (4)T(sub 1)(G) charge transfer transitions in minerals such as goethite, hematite, and jarosite that are products of the aqueous alteration of anhydrous silicates. A shoulder near 0.63 micrometers has also been identified in the absorption feature centered near 0.7 micrometers attributed to oxidized iron in phyllosilicates found predominantly in C- and G-class asteroids reflectance spectra. The coexistence of iron oxides with phyllosilicates in asteroids believed to have undergone aqueous alteration would be expected based upon analogy with terrestrial aqueous alteration and the observed mineralogy of carbonaceous chondrites. The number of low-albedo asteroids having only iron alteration absorption features compared to the number of low-albedo asteroids having spectral characteristics indicative of phyllosilicates is small. Either the conditions under which these asteroids formed are rare, or the iron alteration minerals could be formed in the interiors of objects where phyllosilicates dominate the surface mineralogy.

  17. SORPTION AND ABIOTIC REDOX TRANSFORMATION OF NITROBENZENE AT THE SMECTITE-WATER INTERFACE

    EPA Science Inventory

    The effect of the redox state of structural Fe on the surface reactivity of iron-bearing phyllosilicates in aqueous suspension was investigated using a molecular probe. For this purpose the structural Fe in montmorillonite and ferruginous smectite was chemically reduced by sodium...

  18. Ultra-thin clay layers facilitate seismic slip in carbonate faults.

    PubMed

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

    2017-04-06

    Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

  19. The Mawrth Vallis region of Mars: A potential landing site for the Mars Science Laboratory (MSL) mission.

    PubMed

    Michalski, Joseph R; Jean-PierreBibring; Poulet, François; Loizeau, Damien; Mangold, Nicolas; Dobrea, Eldar Noe; Bishop, Janice L; Wray, James J; McKeown, Nancy K; Parente, Mario; Hauber, Ernst; Altieri, Francesca; Carrozzo, F Giacomo; Niles, Paul B

    2010-09-01

    The primary objective of NASA's Mars Science Laboratory (MSL) mission, which will launch in 2011, is to characterize the habitability of a site on Mars through detailed analyses of the composition and geological context of surface materials. Within the framework of established mission goals, we have evaluated the value of a possible landing site in the Mawrth Vallis region of Mars that is targeted directly on some of the most geologically and astrobiologically enticing materials in the Solar System. The area around Mawrth Vallis contains a vast (>1 × 10⁶ km²) deposit of phyllosilicate-rich, ancient, layered rocks. A thick (>150 m) stratigraphic section that exhibits spectral evidence for nontronite, montmorillonite, amorphous silica, kaolinite, saponite, other smectite clay minerals, ferrous mica, and sulfate minerals indicates a rich geological history that may have included multiple aqueous environments. Because phyllosilicates are strong indicators of ancient aqueous activity, and the preservation potential of biosignatures within sedimentary clay deposits is high, martian phyllosilicate deposits are desirable astrobiological targets. The proposed MSL landing site at Mawrth Vallis is located directly on the largest and most phyllosilicate-rich deposit on Mars and is therefore an excellent place to explore for evidence of life or habitability.

  20. Transmission electron microscope analyses of alteration phases in martian meteorite MIL 090032

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.; Ishii, H. A.; Bradley, J. P.; Taylor, G. J.

    2014-06-01

    The nakhlite group of martian meteorites found in the Antarctic contain varying abundances of both martian and terrestrial secondary alteration phases. The aim of this study was to use transmission electron microscopy (TEM) to compare martian and terrestrial alteration embodied within a single nakhlite martian meteorite find - MIL 090032. Martian alteration veins in MIL 090032 are composed of poorly ordered Fe-smectite phyllosilicate. This poorly-ordered smectite appears to be equivalent to the nanocrystalline phyllosilicate/hydrated amorphous gel phase previously described in the martian alteration veins of other nakhlites. Chemical differences in this nanocrystalline phyllosilicate between different nakhlites imply localised alteration, which occurred close to the martian surface in MIL 090032. Both structurally and compositionally the nakhlite nanocrystalline phyllosilicate shows similarities to the amorphous/poorly ordered phase recently discovered in martian soil by the Mars Curiosity Rover at Rocknest, Gale Crater. Terrestrially derived alteration phases in MIL 090032 include jarosite and gypsum, amorphous silicates, and Fe-oxides and hydroxides. Similarities between the mineralogy and chemistry of the MIL 090032 terrestrial and martian alteration phases suggest the alteration conditions on Mars were similar to those in the Antarctic. At both sites a small amount of fluid at low temperatures infiltrated the rock and became acidic as a result of the conversion of Fe2+ to Fe3+ under oxidising conditions.

  1. Heterogeneous Distribution of Carbonaceous Material in Murchison Matrix: In Situ Observations Using Energy Filtered Transmission Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    2002-01-01

    Energy filtered TEM (Transmission Electron Microscopy) has been used to study the location of carbonaceous material in situ in Murchison matrix. Carbon occurs frequently as narrow rims around sulfide grains, but is rare in regions of matrix that are dominated by phyllosilicates. Additional information is contained in the original extended abstract.

  2. Electronic and elemental properties of the Cu2ZnSn(S,Se)4 surface and grain boundaries

    NASA Astrophysics Data System (ADS)

    Haight, Richard; Shao, Xiaoyan; Wang, Wei; Mitzi, David B.

    2014-01-01

    X-ray and femtosecond UV photoelectron spectroscopy, secondary ion mass spectrometry and photoluminescence imaging were used to investigate the electronic and elemental properties of the CZTS,Se surface and its oxides. Oxide removal reveals a very Cu poor and Zn rich surface relative to bulk composition. O and Na are observed at the surface and throughout the bulk. Upward bending of the valence bands indicates the presence of negative charge in the surface region and the Fermi level is found near the band gap center. The presence of point defects and the impact of these findings on grain boundary properties will be described.

  3. Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering

    SciT

    Solanki, Vanaraj; Joshi, Shalik R.; Mishra, Indrani

    2016-08-07

    The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ∼0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.

  4. Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars

    Wray, J.J.; Milliken, R.E.; Dundas, C.M.; Swayze, G.A.; Andrews-Hanna, J. C.; Baldridge, A.M.; Chojnacki, M.; Bishop, J.L.; Ehlmann, B.L.; Murchie, S.L.; Clark, R.N.; Seelos, F.P.; Tornabene, L.L.; Squyres, S. W.

    2011-01-01

    Columbus crater in the Terra Sirenum region of the Martian southern highlands contains light-toned layered deposits with interbedded sulfate and phyllosilicate minerals, a rare occurrence on Mars. Here we investigate in detail the morphology, thermophysical properties, mineralogy, and stratigraphy of these deposits; explore their regional context; and interpret the crater's aqueous history. Hydrated mineral-bearing deposits occupy a discrete ring around the walls of Columbus crater and are also exposed beneath younger materials, possibly lava flows, on its floor. Widespread minerals identified in the crater include gypsum, polyhydrated and monohydrated Mg/Fe-sulfates, and kaolinite; localized deposits consistent with montmorillonite, Fe/Mg-phyllosilicates, jarosite, alunite, and crystalline ferric oxide or hydroxide are also detected. Thermal emission spectra suggest abundances of these minerals in the tens of percent range. Other craters in northwest Terra Sirenum also contain layered deposits and Al/Fe/Mg-phyllosilicates, but sulfates have so far been found only in Columbus and Cross craters. The region's intercrater plains contain scattered exposures of Al-phyllosilicates and one isolated mound with opaline silica, in addition to more common Fe/Mg-phyllosilicates with chlorides. A Late Noachian age is estimated for the aqueous deposits in Columbus, coinciding with a period of inferred groundwater upwelling and evaporation, which (according to model results reported here) could have formed evaporites in Columbus and other craters in Terra Sirenum. Hypotheses for the origin of these deposits include groundwater cementation of crater-filling sediments and/or direct precipitation from subaerial springs or in a deep (???900 m) paleolake. Especially under the deep lake scenario, which we prefer, chemical gradients in Columbus crater may have created a habitable environment at this location on early Mars. ?? 2011 by the American Geophysical Union.

  5. Mineralogy of Fluvio-Lacustrine Sediments Investigated by Curiosity during the Prime Mission: Implications for Diagenesis

    NASA Astrophysics Data System (ADS)

    Rampe, E. B.; Morris, R. V.; Bish, D. L.; Vaniman, D. T.; Bristow, T.; Chipera, S.; Blake, D. F.; Ming, D. W.; Farmer, J.; Morrison, S. M.; Treiman, A. H.; Achilles, C.; Crisp, J.; Des Marais, D. J.; Downs, R. T.; Morookian, J. M.; Sarrazin, P.; Spanovich, N.; Yen, A.

    2014-12-01

    The Mars Science Laboratory rover Curiosity investigated sedimentary rocks that were deposited in a diversity of fluvio-lacustrine settings. The entire science payload was employed to characterize the mineralogy and chemistry of the Sheepbed mudstone at Yellowknife Bay and the Windjana sandstone at the Kimberley. Data from the CheMin instrument, a transmission X-ray diffractometer, were used to determine the quantitative mineralogy of both samples. The Sheepbed mudstone contains detrital basaltic minerals, calcium sulfates, iron oxides or hydroxides, iron sulfides, trioctahedral smectite, and amorphous material. The mineral assemblage and chemical data from APXS suggest that the trioctahedral smectite and magnetite formed authigenically as a result of alteration of olivine. The apparent lack of higher-grade phyllosilicates (e.g., illite and chlorite) and the presence of anhydrite indicate diagenesis at ~50-80 ºC. The mineralogy of the Windjana sandstone is different than the Sheepbed mudstone. Windjana contains significant abundances of K-feldspar, low- and high-Ca pyroxenes, magnetite, phyllosilicates, and amorphous material. At least two distinct phyllosilicate phases exist: a 10 Å phase and a component that is expanded with a peak at ~11.8 Å. The identity of the expanded phase is currently unknown, but could be a smectite with interlayer H2O, and the 10 Å phase could be illite or collapsed smectite. Further work is necessary to characterize the phyllosilicates, but the presence of illite could suggest that Windjana experienced burial diagenesis. Candidates for the cementing agents include fine-grained phyllosilicates, Fe-oxides, and/or amorphous material. Interpretations of CheMin data from the Windjana sandstone are ongoing at the time of writing, but we will present an estimate of the composition of the amorphous material from mass balance calculations using the APXS bulk chemistry and quantitative mineralogy from CheMin.

  6. Mineralogy of Fluvio-Lacustrine Sediments Investigated by Curiosity During the Prime Mission: Implications for Diagenesis

    NASA Technical Reports Server (NTRS)

    Rampe, Elizabeth B.; Morris, R. V.; Bish, D. L.; Vaniman, D. T.; Bristow, T. F.; Chipera, S. J.; Blake, D. F.; Ming, D. W.; Farmer, J. D.; Morrison, S. M.; hide

    2014-01-01

    The Mars Science Laboratory rover Curiosity investigated sedimentary rocks that were deposited in a diversity of fluvio-lacustrine settings. The entire science payload was employed to characterize the mineralogy and chemistry of the Sheepbed mudstone at Yellowknife Bay and the Windjana sandstone at the Kimberley. Data from the CheMin instrument, a transmission Xray diffractometer, were used to determine the quantitative mineralogy of both samples. The Sheepbed mudstone contains detrital basaltic minerals, calcium sulfates, iron oxides or hydroxides, iron sulfides, trioctahedral smectite, and amorphous material. The mineral assemblage and chemical data from APXS suggest that the trioctahedral smectite and magnetite formed authigenically as a result of alteration of olivine. The apparent lack of higher-grade phyllosilicates (e.g., illite and chlorite) and the presence of anhydrite indicate diagenesis at 50- 80 ºC. The mineralogy of the Windjana sandstone is different than the Sheepbed mudstone. Windjana contains significant abundances of K-feldspar, low- and high-Ca pyroxenes, magnetite, phyllosilicates, and amorphous material. At least two distinct phyllosilicate phases exist: a 10 Å phase and a component that is expanded with a peak at 11.8 Å. The identity of the expanded phase is currently unknown, but could be a smectite with interlayer H2O, and the 10 Å phase could be illite or collapsed smectite. Further work is necessary to characterize the phyllosilicates, but the presence of illite could suggest that Windjana experienced burial diagenesis. Candidates for the cementing agents include fine-grained phyllosilicates, Fe-oxides, and/or amorphous material. Interpretations of CheMin data from the Windjana sandstone are ongoing at the time of writing, but we will present an estimate of the composition of the amorphous material from mass balance calculations using the APXS bulk chemistry and quantitative mineralogy from CheMin.

  7. Calculation of point defect concentration in Cu2ZnSnS4: Insights into the high-temperature equilibrium and quenching

    NASA Astrophysics Data System (ADS)

    Kosyak, V.; Postnikov, A. V.; Scragg, J.; Scarpulla, M. A.; Platzer-Björkman, C.

    2017-07-01

    Herein, we study the native point defect equilibrium in Cu2ZnSnS4 (CZTS) by applying a statistical thermodynamic model. The stable chemical-potential space (SCPS) of CZTS at an elevated temperature was estimated directly, on the basis of deviations from stoichiometry calculated for the different combinations of chemical potential of the components. We show that the SCPS is narrow due to high concentration of (" separators="|VCu --ZnC u + ) complex which is dominant over other complexes and isolated defects. The CZTS was found to have p-type conductivity for both stoichiometric and Cu-poor/Zn-rich composition. It is established that the reason for this is that the majority of donor-like ZnC u + antisites are involved in the formation of (" separators="|VCu --ZnC u + ) complex making CuZ n - dominant and providing p-type conductivity even for Cu-poor/Zn-rich composition. However, our calculation reveals that the hole concentration is almost insensitive to the variation of the chemical composition within the composition region of the single-phase CZTS due to nearly constant concentration of dominant charged defects. The calculations for the full equilibrium and quenching indicate that hole concentration is strongly dependent on the annealing temperature and decreases substantially after the drastic cooling. This means that the precise control of annealing temperature and post-annealing cooling rate are critical for tuning the electrical properties of CZTS.

  8. The role of interparticle heterogeneities in the selenization pathway of Cu-Zn-Sn-S nanoparticle thin films: A real-time study

    SciT

    Carter, Nathaniel J.; Mainz, Roland; Walker, Bryce C.

    2015-06-10

    Real-time energy dispersive x-ray diffraction (EDXRD) analysis has been utilized to observe the selenization of Cu-Zn-Sn-S nanoparticle films coated from three nanoparticle populations: Cu- and Sn-rich particles roughly 5 nm in size, Zn-rich nanoparticles ranging from 10 to 20 nm in diameter, and a mixture of both types of nanoparticles (roughly 1:1 by mass), which corresponds to a synthesis recipe yielding CZTSSe solar cells with reported total-area efficiencies as high as 7.9%. The EDXRD studies presented herein show that the formation of copper selenide intermediates during the selenization of mixed-particle films can be primarily attributed to the small, Cu- andmore » Sn-rich particles. Moreover, the formation of these copper selenide phases represents the first stage of the CZTSSe grain growth mechanism. The large, Zn-rich particles subsequently contribute their composition to form micrometer-sized CZTSSe grains. In conclusion, these findings enable further development of a previously proposed selenization pathway to account for the roles of interparticle heterogeneities, which in turn provides a valuable guide for future optimization of processes to synthesize high quality CZTSSe absorber layers.« less

  9. Petrology and geochemistry of Antarctic micrometeorites

    NASA Astrophysics Data System (ADS)

    Kurat, Gero; Koeberl, Christian; Presper, Thomas; Brandstätter, Franz; Maurette, Michel

    1994-09-01

    The petrology and geochemistry of twentythree chondritic dust particles with masses of 1-47 μg (sizes 100-400 μm) were recovered from blue ice near Cap Prudhomme, Antarctica, and studied by INAA, ASEM, EMPA, and optical microscopy. Sample selection criteria were irregular shape and (for a subsample) black color, with the aim of studying as many unmelted micrometeorites (MMs) as possible. Of thirteen unmelted MMs, six were phyllosilicate-dominated MMs, and seven were coarsegrained crystalline MMs consisting mainly of olivine and pyroxene. The remaining ten particles were largely melted and consisted of a foamy melt with variable amounts of relic phases (scoriaceous MMs). Thus, of the black particles selected, an astonishing portion, 40% (by number), consisted of largely unmelted MMs. Although unmelted, most phyllosilicate MMs have been thermally metamorphosed to a degree that most of the phyllosilicates were destroyed, but not melted. The original preterrestrial mineralogy is occasionally preserved and consists of serpentine-like phyllosilicates with variable amounts of cronstedtite, tochilinite-like oxides, olivine, and pyroxene. The crystalline MMs consist of olivine, low-Ca pyroxene, tochilinite-like oxides, and occasional Ni-poor metal. Relics in scoriaceous MMs consist of the same phases. Mineral compositions and the coexistence of phyllosilicates with anhydrous phases are typical of CM and CR-type carbonaceous chondrites. However, the olivine/pyroxene ratio (~ 1) and the lack of carbonates, sulfates, and of very Fe-poor, refractory element-rich olivines and pyroxenes sets the MMs apart from CM and CR chondrites. The bulk chemistry of the phyllosilicate MMs is similar to that of CM chondrites. However, several elements are either depleted (Ca, Ni, S, less commonly Na, Mg, and Mn) or enriched (K, Fe, As, Br, Rb, Sb, and Au) in MMs as compared to CM chondrites. Similar depletions and enrichments are also found in the scoriaceous MMs. We suggest that the

  10. CI chondrite-like clasts in the Nilpena polymict ureilite - Implications for aqueous alteration processes in CI chondrites

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.; Prinz, Martin

    1992-01-01

    Petrographic studies of Nilpena polymict ureilite have revealed the presence of small quantities of carbonaceous chondrite matrix clasts. Detailed electron microprobe and TEM studies show that the chemistry and fine-scale mineralogy of one of these clasts is consistent with CI carbonaceous chondrite matrix. Compared to Orgeuil, the phyllosilicate, sulfide, and oxide mineralogy suggests that the Nilpena clasts may represent a less altered type of CI matrix. It is suggested that increased oxidation and aqueous alteration of Nilpena-type materials could result in the formation of the type of mineral assemblage observed in Orgueil. Increased alteration produces progressive more Mg-rich phyllosilicates and more Fe(3+)-rich iron oxides, such as ferrihydrite. As a function of increased alteration, Ca is also progressively leached from the matrix material to form carbonate veins. The depletion of Ca in CI chondrite matrices suggests the Ivuna and Alais may be intermediate in their degree of alteration to Nilpena and Orgueil.

  11. Volatile and organic compositions of sedimentary rocks in Yellowknife Bay, Gale crater, Mars.

    PubMed

    Ming, D W; Archer, P D; Glavin, D P; Eigenbrode, J L; Franz, H B; Sutter, B; Brunner, A E; Stern, J C; Freissinet, C; McAdam, A C; Mahaffy, P R; Cabane, M; Coll, P; Campbell, J L; Atreya, S K; Niles, P B; Bell, J F; Bish, D L; Brinckerhoff, W B; Buch, A; Conrad, P G; Des Marais, D J; Ehlmann, B L; Fairén, A G; Farley, K; Flesch, G J; Francois, P; Gellert, R; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; Leshin, L A; Lewis, K W; McLennan, S M; Miller, K E; Moersch, J; Morris, R V; Navarro-González, R; Pavlov, A A; Perrett, G M; Pradler, I; Squyres, S W; Summons, R E; Steele, A; Stolper, E M; Sumner, D Y; Szopa, C; Teinturier, S; Trainer, M G; Treiman, A H; Vaniman, D T; Vasavada, A R; Webster, C R; Wray, J J; Yingst, R A

    2014-01-24

    H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

  12. Surface-complexation synthesis of silica-supported high-loading well-dispersed reducible nano-Co3O4 catalysts using CoIII ammine hydroxo complexes

    NASA Astrophysics Data System (ADS)

    Zhang, Weidong; Pan, Feng; Li, Jinjun; Wang, Zhen; Ding, Wei; Qin, Yi; Wu, Feng

    2018-06-01

    Silica-supported highly dispersed cobalt oxides prepared by adsorption are likely to be poorly reducible Co-phyllosilicates or CoO species. Here we report the synthesis of silica-supported monodispersed spinel nano-Co3O4 catalysts by inner-sphere complexation using CoIII ammine hydroxo complexes as precursors. The precursors were facilely prepared by stirring ammoniacal CoII solutions exposed to air. The cobalt loadings (up to 188 mg/g) and particle sizes (3-10 nm) were tailored by successive complexation-calcination cycles. Such catalysts showed significantly superior reducibility and catalytic activity in complete propane oxidation in comparison to supported Co-phyllosilicates and CoO. A further development of this synthesis process may provide a variety of cobalt-based catalysts for important catalytic applications.

  13. Stability of hydrated minerals on Mars

    NASA Astrophysics Data System (ADS)

    Cloutis, Edward A.; Craig, Michael A.; Mustard, John F.; Kruzelecky, Roman V.; Jamroz, Wes R.; Scott, Alan; Bish, David L.; Poulet, François; Bibring, Jean-Pierre; King, Penelope L.

    2007-10-01

    The validity of recent identification of various hydrated minerals (kieserite, gypsum, hexahydrite, nontronite, chamosite, and montmorillonite) on Mars was assessed by exposing these minerals to simulated Martian surface conditions of atmospheric composition and pressure, temperature, and ultraviolet light irradiation. When exposed to such conditions the hydrated minerals exhibit in general, greater losses of interlayer H2O than structural OH. Minerals such as gypsum that contain structural H2O are more resistant to H2O loss than phyllosilicates. The partial loss of OH in some of the phyllosilicates is not accompanied by a measurable and systematic change in the wavelength position or intensity of metal-OH absorption bands. The characteristic absorption features that allow for identification of these minerals on Mars may be reduced in intensity, but are nevertheless largely preserved.

  14. Aqueous alteration detection in Tikhonravov crater, Mars

    NASA Astrophysics Data System (ADS)

    Mancarella, F.; Fonti, S.; Alemanno, G.; Orofino, V.; Blanco, A.

    2018-03-01

    The existence of a wet period lasting long enough to allow the development of elementary forms of life on Mars has always been a very interesting issue. Given this perspective, the research for geological markers of such occurrences has been continually pursued. Once a favorable site is detected, effort should be spent to get as much information as possible aimed at a precise assessment of the genesis and evolution of the areas showing the selected markers. In this work, we discuss the recent finding of possible deposits pointing to the past existence of liquid water in Tikhonravov crater located in Arabia Terra. Comparison of CRISM spectra and those of laboratory minerals formed by aqueous alteration has led us to the conclusion that the studied areas within the impact crater host phyllosilicates deposits. In addition, analysis of the CRISM spectra has resulted in the tentative identification of carbonates mixed with phyllosilicates.

  15. Volatile and organic compositions of sedimentary rocks in Yellowknife Bay, Gale crater, Mars

    Ming, D. W.; Archer, P.D.; Glavin, D.P.; Eigenbrode, J.L.; Franz, H.B.; Sutter, B.; Brunner, A.E.; Stern, J.C.; Freissinet, C.; McAdam, A.C.; Mahaffy, P.R.; Cabane, M.; Coll, P.; Campbell, J.L.; Atreya, S.K.; Niles, P.B.; Bell, J.F.; Bish, D.L.; Brinckerhoff, W.B.; Buch, A.; Conrad, P.G.; Des Marais, D.J.; Ehlmann, B.L.; Fairén, A.G.; Farley, K.; Flesch, G.J.; Francois, P.; Gellert, Ralf; Grant, J. A.; Grotzinger, J.P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J.A.; Leshin, L.A.; Lewis, K.W.; McLennan, S.M.; Miller, Karl E.; Moersch, J.; Morris, R.V.; Navarro- González, R.; Pavlov, A.A.; Perrett, G.M.; Pradler, I.; Squyres, S. W.; Summons, Roger E.; Steele, A.; Stolper, E.M.; Sumner, D.Y.; Szopa, C.; Teinturier, S.; Trainer, M.G.; Treiman, A.H.; Vaniman, D.T.; Vasavada, A.R.; Webster, C.R.; Wray, J.J.; Yingst, R.A.

    2014-01-01

    H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

  16. Solubility of noble gases in serpentine - Implications for meteoritic noble gas abundances

    NASA Technical Reports Server (NTRS)

    Zaikowski, A.; Schaeffer, O. A.

    1979-01-01

    An investigation of the solubilities of the noble gases from synthesis and solubility studies of the sheet silicate mineral serpentine in carbonaceous chondrites is presented. Hydrothermal synthesis and exchange experiments were made at 340C and 1 kbar with noble gas partial pressures from 2 times 10 to the -8th power to 0.1 atm. The measured distribution coefficients for noble gases are not sufficiently high to account for the trapped noble gases in carbonaceous chondrites by exchange in solar nebula if meteoritic minerals have comparable distribution coefficients. Also, serpentine gains and loses noble gases to approach equilibrium values with the terrestrial atmosphere, indicating that this exposure may have influenced the noble gas abundances in phyllosilicate minerals of these chondrites. The dispersion of K-Ar ages of carbonaceous chondrites could be the result of phyllosilicates approaching equilibrium solubility of atmospheric Ar-40.

  17. Test and Delivery of the Chemin Mineralogical Instrument for Mars Science Laboratory

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Vaniman, D.; Anderson, R.; Bish, D.; Chipera, S.; Chemtob, S.; Crisp, J.; DesMarais, D. J.; Downs, R.; Feldman, S.; hide

    2010-01-01

    The CheMin mineralogical instrument on MSL will return quantitative powder X-ray diffraction data (XRD) and qualitative X-ray fluorescence data (XRF; 14phyllosilicate identification, could be detected.

  18. Field- to nano-scale evidence for weakening mechanisms along the fault of the 2016 Amatrice and Norcia earthquakes, Italy

    NASA Astrophysics Data System (ADS)

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Doglioni, Carlo

    2017-08-01

    In August and October 2016, two normal fault earthquakes (Mw 6.0 and Mw 6.5, respectively) struck the Amatrice-Norcia area in the central Apennines, Italy. The mainshocks nucleated at depths of 7-9 km with the co-seismic slip propagating upward along the Mt. Gorzano Fault (MGF) and Mt. Vettore Fault System (MVFS). To recognize possible weakening mechanisms along the carbonate-hosted seismogenic faults that generated the Amatrice-Norcia earthquakes, the fresh co-seismic fault exposure (i.e., "nastrino") exposed along the Mt. Vettoretto Fault was sampled and analyzed. This exposed fault belongs to the MVFS and was exhumed from 2-3 km depth. Over the fresh fault surface, phyllosilicates concentrated and localized along mm- to μm-thick layers, and truncated clasts and fluid-like structures were found. At the nano-scale, instead of their common platy-lamellar crystallographic texture, the analyzed phyllosilicates consist of welded nm-thick nanospherules and nanotubes similar to phyllosilicates deformed in rotary shear apparatus at seismic velocities or altered under high hydrothermal temperatures (> 250 °C). Moreover, the attitude of the Mt. Vettoretto Fault and its kinematics inferred from exposed slickenlines are consistent with the co-seismic fault and slip vectors obtained from the focal mechanisms computed for the 2016 mainshocks. All these pieces of evidence suggest that the Mt. Vettoretto Fault slipped seismically during past earthquakes and that co-seismic slip was assisted and facilitated at depths of < 3 km by phyllosilicate-rich layers and overpressured fluids. The same weakening processes may also have been decisive in facilitating the co-seismic slip propagation during the 2016 Mw 6.0 Amatrice and Mw 6.5 Norcia earthquakes. The microstructures found along the Mt. Vettoretto Fault, which is certainly a seismogenic fault, provide a realistic synoptic picture of co-seismic processes and weakening mechanisms that may occur in carbonate-hosted seismogenic

  19. Why is it so difficult to classify Renazzo-type (CR) carbonaceous chondrites? - Implications from TEM observations of matrices for the sequences of aqueous alteration

    NASA Astrophysics Data System (ADS)

    Abreu, Neyda M.

    2016-12-01

    A number of different classifications have been proposed for the CR chondrites; this study aims at reconciling these different schemes. Mineralogy-based classification has proved particularly challenging for weakly to moderately altered CRs because incipient mineral replacement and elemental mobilization arising from aqueous alteration only affected the most susceptible primary phases, which are generally located in the matrix. Secondary matrix phases are extremely fine-grained (generally sub-micron) and heterogeneously mixed with primary nebular materials. Compositional and isotopic classification parameters are fraught with confounding factors, such as terrestrial weathering, impact processes, and variable abundance of clasts from different regions of the CR parent body or from altogether different planetary bodies. Here, detailed TEM observations from eighteen FIB sections retrieved from the matrices of nine Antarctic CR chondrites (EET 96259, GRA 95229, GRO 95577, GRO 03116, LAP 02342, LAP 04516, LAP 04720, MIL 07525, and MIL 090001) are presented, representing a range of petrologic types. Amorphous Fe-Mg silicates are found to be the dominant phase in all but the most altered CR chondrite matrices, which still retain significant amounts of these amorphous materials. Amorphous Fe-Mg silicates are mixed with phyllosilicates at the nanometer scale. The ratio of amorphous Fe-Mg silicates to phyllosilicates decreases as: (1) the size of phyllosilicates, (2) abundance of magnetite, and (3) replacement of Fe-Ni sulfides increase. Carbonates are only abundant in the most altered CR chondrite, GRO 95577. Nanophase Fe-Ni metal and tochilinite are present small abundances in most CR matrices. Based on the presence, abundance and size of phyllosilicates with respect to amorphous Fe-Mg silicates, the sub-micron features of CR chondrites have been linked to existing classification sequences, and possible reasons for inconsistencies among classification schemes are discussed.

  20. Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal

    SciT

    Zhao, Linduo; Dong, Hailiang; Kukkadapu, Ravi K.

    2015-05-05

    Redox cycling of structural Fe in phyllosilicates provides a potential method to remediate nitrate contamination in natural environment. Past research has only studied chemical redox cycles or a single biologically mediated redox cycle of Fe in phyllosilicates. The objective of this research was to study three microbially driven redox cycles of Fe in one phyllosilicate, nontronite (NAu-2). During the reduction phase structural Fe(III) in NAu-2 served as electron acceptor, lactate as electron donor, AQDS as electron shuttle, and dissimilatory Fe(III)-reducing bacteria Shewanella putrefaciens CN32 as mediator in bicarbonate-buffered and PIPES-buffered media. During the oxidation phase, biogenic Fe(II) served an electronmore » donor, nitrate as electron acceptor, and nitrate-dependent Fe(II)-oxidizing bacteria Pseudogulbenkiania sp. strain 2002 as mediator in the same media. For all three cycles, structural Fe in NAu-2 was able to reversibly undergo 3 redox cycles without significant reductive or oxidative dissolution. X-ray diffraction and scanning and transmission electron microscopy revealed that NAu-2 was the dominant residual mineral throughout the 3 redox cycles with some dissolution textures but no significant secondary mineralization. Mössbauer spectroscopy revealed that Fe(II) in bio-reduced samples likely occurred in two distinct environments, at edges and the interior of the NAu-2 structure. Nitrate was completely reduced to nitrogen gas under both buffer conditions and this extent and rate did not change with Fe redox cycles. Mössbauer spectroscopy further revealed that nitrate reduction was coupled to predominant/preferred oxidation of edge Fe(II). These results suggest that structural Fe in phyllosilicates may represent a renewable source to continuously remove nitrate in natural environments.« less

  1. Analysis of mineral matrices of planetary soil analogues from the Utah Desert

    NASA Astrophysics Data System (ADS)

    Kotler, J. M.; Quinn, R. C.; Foing, B. H.; Martins, Z.; Ehrenfreund, P.

    2011-07-01

    Phyllosilicate minerals and hydrated sulphate minerals have been positively identified on the surface of Mars. Studies conducted on Earth indicate that micro-organisms influence various geochemical and mineralogical transitions for the sulphate and phyllosilicate minerals. These minerals in turn provide key nutrients to micro-organisms and influence microbial ecology. Therefore, the presence of these minerals in astrobiology studies of Earth-Mars analogue environments could help scientists better understand the types and potential abundance of micro-organisms and/or biosignatures that may be encountered on Mars. Bulk X-ray diffraction of samples collected during the EuroGeoMars 2009 campaign from the Mancos Shale, the Morrison and the Dakota formations near the Mars Desert Research Station in Utah show variable but common sedimentary mineralogy with all samples containing quantities of hydrated sulphate minerals and/or phyllosilicates. Analysis of the clay fractions indicate that the phyllosilicates are interstratified illite-smectites with all samples showing marked changes in the diffraction pattern after ethylene glycol treatment and the characteristic appearance of a solvated peak at ˜17 Å. The smectite phases were identified as montmorillonite and nontronite using a combination of the X-ray diffraction data and Fourier-Transform Infrared Spectroscopy. The most common sulphate mineral in the samples is hydrated calcium sulphate (gypsum), although one sample contained detectable amounts of strontium sulphate (celestine). Carbonates detected in the samples are variable in composition and include pure calcium carbonate (calcite), magnesium-bearing calcium carbonate (dolomite), magnesium, iron and manganese-bearing calcium carbonate (ankerite) and iron carbonate (siderite). The results of these analyses when combined with organic extractions and biological analysis should help astrobiologists and planetary geologists better understand the potential relationships

  2. Toxic Chemicals in the Soil Environment. Volume 1. Chemical Properties and Characterization of Soils

    DTIC Science & Technology

    1985-06-01

    ORGANIZATION NAME 4,ND ADJR$55 10. PROGRAM ELEMENT, PROJECT, TASK AREA I WORK UNIT NUMBERS I’t iso.:m - w.XI okla’ýoria t~t { iti i’.water, &’ k 1...and relative sizes of ions commonly occurring in phyllosilicates ... ....... .... 12 The tet:ahedron formed by coordination of Si by four oxvgens...12 3 The octahedron formed by coordination of a cation by six oxygens ................. ...... . . 13 4 Linked Si 60 rings

  3. Opportunity Microscopic Imager Results from the Western Rim of Endeavour Crater, Mars

    NASA Astrophysics Data System (ADS)

    Arvidson, R. E.; Herkenhoff, K. E.; Mittlefehldt, D. W.; Sullivan, R. J., Jr.

    2015-12-01

    Opportunity has been exploring exposures of Noachian-age rocks along the rim of Endeavour crater since August 2011, motivated by orbital spectral evidence for phyllosilicates at multiple locations along the crater's rim. As reported previously, Opportunity discovered multiple bright linear features at "Cape York" that have been interpreted as veins of Ca sulfate deposited in bedrock fractures, and in-situ measurements are consistent with the presence of smectite clays in rocks and veneers on the east side of Cape York. The inferred neutral pH and relatively low temperature of the fluids involved in multiple phases of alteration would have provided a habitable environment if life existed on Mars at that time. Because Opportunity can no longer directly sense phyllosilicate mineralogy with the MiniTES or Mössbauer spectrometers, it is focusing on characterizing outcrop multispectral reflectance with Pancam, chemistry with the Alpha Particle X-ray Spectrometer and microtexture with the Microscopic Imager (MI) of potential phyllosilicate host rocks. While traversing the western side of "Murray Ridge," Opportunity found outcrops of breccia that are similar in texture and chemical composition to the Shoemaker Formation rocks exposed at Cape York. MI images of the breccias show cm-size angular clasts in fine-grained matrix, consistent with an impact origin. At "Cook Haven," the rover wheels overturned a few rocks, exposing dark Mn-rich coatings and haloes on brighter sulfates (Figure 1), which suggest aqueous precipitation followed by interaction with a strong oxidant. The dark, resistant coatings on "Thessaloniki" are less than about 0.1 mm thick, barely resolved in places by MI stereogrammetry. Opportunity's mission continues, with the rover exploring more exposures of phyllosilicates detected from orbit on "Cape Tribulation." The latest MI results, including observations in "Marathon Valley," will be presented at the conference.

  4. Mineral abundances at the final four curiosity study sites and implications for their formation

    NASA Astrophysics Data System (ADS)

    Poulet, F.; Carter, J.; Bishop, J. L.; Loizeau, D.; Murchie, S. M.

    2014-03-01

    A component of the landing site selection process for the Mars Science Laboratory (MSL) involved the presence of phyllosilicates as the main astrobiological targets. Gale crater was selected as the MSL landing site from among 4 down selected study sites (Gale, Eberswalde and Holden craters, Mawrth Vallis) that addressed the primary scientific goal of assessing the past habitability of Mars. A key constraint on the formation process of these phyllosilicate-bearing deposits is in the precise mineralogical composition. We present a reassessment of the mineralogy of the sites combined with a determination of the modal mineralogy of the major phyllosilicate-bearing deposits of the four final study sites from the modeling of near-infrared spectra using a radiative transfer model. The largest abundance of phyllosilicates (30-70%) is found in Mawrth Vallis, the lowest one in Eberswalde (<25%). Except for Mawrth Vallis, the anhydrous phases (plagioclase, pyroxenes and martian dust) are the dominant phases, suggesting formation conditions with a lower alteration grade and/or a post-formation mixing with anhydrous phases. The composition of Holden layered deposits (mixture of saponite and micas with a total abundance in the range of 25-45%) suggests transport and deposition of altered basalts of the Noachian crust without major chemical transformation. For Eberswalde, the modal mineralogy is also consistent with detrital clays, but the presence of opaline silica indicates that an authigenic formation occurred during the deposition. The overall composition including approximately 20-30% smectite detected by MSL in the rocks of Yellow-knife Bay area interpreted to be material deposited on the floor of Gale crater by channels (http://www.nasa.gov/mission_pages/msl/news/msl20130312.html).

  5. Structural and spectroscopic changes to natural nontronite induced by experimental impacts between 10 and 40 GPa

    NASA Astrophysics Data System (ADS)

    Friedlander, Lonia R.; Glotch, Timothy D.; Bish, David L.; Dyar, M. Darby; Sharp, Thomas G.; Sklute, Elizabeth C.; Michalski, Joseph R.

    2015-05-01

    Many phyllosilicate deposits remotely detected on Mars occur within bombarded terrains. Shock metamorphism from meteor impacts alters mineral structures, producing changed mineral spectra. Thus, impacts have likely affected the spectra of remotely sensed Martian phyllosilicates. We present spectral analysis results for a natural nontronite sample before and after laboratory-generated impacts over five peak pressures between 10 and 40 GPa. We conducted a suite of spectroscopic analyses to characterize the sample's impact-induced structural and spectral changes. Nontronite becomes increasingly disordered with increasing peak impact pressure. Every infrared spectroscopic technique used showed evidence of structural changes at shock pressures above ~25 GPa. Reflectance spectroscopy in the visible near-infrared region is primarily sensitive to the vibrations of metal-OH and interlayer H2O groups in the nontronite octahedral sheet. Midinfrared (MIR) spectroscopic techniques are sensitive to the vibrations of silicon and oxygen in the nontronite tetrahedral sheet. Because the tetrahedral and octahedral sheets of nontronite deform differently, impact-driven structural deformation may contribute to differences in phyllosilicate detection between remote sensing techniques sensitive to different parts of the nontronite structure. Observed spectroscopic changes also indicated that the sample's octahedral and tetrahedral sheets were structurally deformed but not completely dehydroxylated. This finding is an important distinction from previous studies of thermally altered phyllosilicates in which dehydroxylation follows dehydration in a stepwise progression preceding structural deformation. Impact alteration may thus complicate mineral-specific identifications based on the location of OH-group bands in remotely detected spectra. This is a key implication for Martian remote sensing arising from our results.

  6. Looking Towards Curiosity's Canyon Path: a 4 km Sequence of Gully, Debris Deposits, and Fan/Deltas Which are Bordered by a Sloping Bedform-Capped Plain and Crossed by Lake Shorelines

    NASA Technical Reports Server (NTRS)

    Dietrich, W. E.; Palucis, M. C.; Parker, T.; Rubin, D.; dePablo, M. A.; Oehler, D. Z.; Bridges, N. T.

    2014-01-01

    The Curiosity Rover is headed towards layered outcrops that appear to be rich in phyllosilicates and sulphates with the expectation of an eventual ascent up Mt. Sharp. One likely will take the rover up a well-defined canyon. Inspection of CTX and HiRISE imagery and topography (5 m contour intervals) reveal a rich geomorphic sequence that may be encountered during the journey.

  7. Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Fairén, Alberto G.; Michalski, Joseph R.; Gago-Duport, Luis; Baker, Leslie L.; Velbel, Michael A.; Gross, Christoph; Rampe, Elizabeth B.

    2018-03-01

    The ancient rock record for Mars has long been at odds with climate modelling. The presence of valley networks, dendritic channels and deltas on ancient terrains points towards running water and fluvial erosion on early Mars1, but climate modelling indicates that long-term warm conditions were not sustainable2. Widespread phyllosilicates and other aqueous minerals on the Martian surface3-6 provide additional evidence that an early wet Martian climate resulted in surface weathering. Some of these phyllosilicates formed in subsurface crustal environments5, with no association with the Martian climate, while other phyllosilicate-rich outcrops exhibit layered morphologies and broad stratigraphies7 consistent with surface formation. Here, we develop a new geochemical model for early Mars to explain the formation of these clay-bearing rocks in warm and wet surface locations. We propose that sporadic, short-term warm and wet environments during a generally cold early Mars enabled phyllosilicate formation without requiring long-term warm and wet conditions. We conclude that Mg-rich clay-bearing rocks with lateral variations in mixed Fe/Mg smectite, chlorite, talc, serpentine and zeolite occurrences formed in subsurface hydrothermal environments, whereas dioctahedral (Al/Fe3+-rich) smectite and widespread vertical horizonation of Fe/Mg smectites, clay assemblages and sulphates formed in variable aqueous environments on the surface of Mars. Our model for aluminosilicate formation on Mars is consistent with the observed geological features, diversity of aqueous mineralogies in ancient surface rocks and state-of-the-art palaeoclimate scenarios.

  8. Textural evidence bearing on the origin of isolated olivine crystals in C2 carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Richardson, S. M.; Mcsween, H. Y., Jr.

    1978-01-01

    In some cases the mechanical competence of chondrules in carbonaceous chondrites has been reduced by alteration of their mesostasis glass to friable phyllosilicate, providing a mechanism by which euhedral olivines can be separated from chondrules. Morphological features of isolate olivine grains found in carbonaceous chondrites are similar to those of olivine phenocrysts in chondrules. These observations suggest that the isolated olivine grains formed in chondrules, by crystallization from a liquid, rather than by condensation from a vapor.

  9. Fabric controls on the brittle failure of folded gneiss and schist

    NASA Astrophysics Data System (ADS)

    Agliardi, Federico; Zanchetta, Stefano; Crosta, Giovanni B.

    2014-12-01

    We experimentally studied the brittle failure behaviour of folded gneiss and schist. Rock fabric and petrography were characterised by meso-structural analyses, optical microscopy, X-ray diffraction, and SEM imaging. Uniaxial compression, triaxial compression and indirect tension laboratory tests were performed to characterise their strength and stress-strain behaviour. Fracture patterns generated in compression were resolved in 3D through X-ray computed tomography at different resolutions (30 to 625 μm). Uniaxial compression tests revealed relatively low and scattered values of unconfined compressive strength (UCS) and Young's modulus, with no obvious relationships with the orientation of foliation. Samples systematically failed in four brittle modes, involving different combinations of shear fractures along foliation or parallel to fold axial planes, or the development of cm-scale shear zones. Fracture quantification and microstructural analysis show that different failure modes occur depending on the mutual geometrical arrangement and degree of involvement of two distinct physical anisotropies, i.e. the foliation and the fold axial planes. The Axial Plane Anisotropy (APA) is related to micro-scale grain size reduction and shape preferred orientation within quartz-rich domains, and to mechanical rotation or initial crenulation cleavage within phyllosilicate-rich domains at fold hinge zones. In quartz-rich rocks (gneiss), fracture propagation through quartz aggregates forming the APA corresponds to higher fracture energy and strength than found for fracture through phyllosilicate-rich domains. This results in a strong dependence of strength on the failure mode. Conversely, in phyllosilicate-rich rocks (schist), all the failure modes are dominated by the strength of phyllosilicates, resulting in a sharp reduction of strength anisotropy.

  10. SciT

    Rivkin, Andrew S.; Thomas, Cristina A.; Howell, Ellen S.

    Asteroids belonging to the Ch spectral taxonomic class are defined by the presence of an absorption near 0.7 μm, which is interpreted as due to Fe-bearing phyllosilicates. Phyllosilicates also cause strong absorptions in the 3 μm region, as do other hydrated and hydroxylated minerals and H{sub 2}O ice. Over the past decade, spectral observations have revealed different 3 μm band shapes in the asteroid population. Although a formal taxonomy is yet to be fully established, the “Pallas-type” spectral group is most consistent with the presence of phyllosilicates. If Ch class and Pallas type are both indicative of phyllosilicates, then allmore » Ch-class asteroids should also be Pallas-type. In order to test this hypothesis, we obtained 42 observations of 36 Ch-class asteroids in the 2 to 4 μm spectral region. We found that 88% of the spectra have 3 μm band shapes most consistent with the Pallas-type group. This is the first asteroid class for which such a strong correlation has been found. Because the Ch class is defined by the presence of an absorption near 0.7 μm, this demonstrates that the 0.7 μm band serves not only as a proxy for the presence of a band in the 3 μm region, but specifically for the presence of Pallas-type bands. There is some evidence for a correlation between band depth at 2.95 μm and absolute magnitude and/or albedo. However, we find only weak correlations between 2.95 μm band depth and semimajor axis. The connection between band depths in the 0.7 and 3 μm regions is complex and in need of further investigation.« less

  11. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

    PubMed

    Poch, Olivier; Jaber, Maguy; Stalport, Fabien; Nowak, Sophie; Georgelin, Thomas; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-03-01

    Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate.

  12. Orbital evidence for clay and acidic sulfate assemblages on Mars based on mineralogical analogs from Rio Tinto, Spain

    NASA Astrophysics Data System (ADS)

    Kaplan, Hannah H.; Milliken, Ralph E.; Fernández-Remolar, David; Amils, Ricardo; Robertson, Kevin; Knoll, Andrew H.

    2016-09-01

    Outcrops of hydrated minerals are widespread across the surface of Mars, with clay minerals and sulfates being commonly identified phases. Orbitally-based reflectance spectra are often used to classify these hydrated components in terms of a single mineralogy, although most surfaces likely contain multiple minerals that have the potential to record local geochemical conditions and processes. Reflectance spectra for previously identified deposits in Ius and Melas Chasma within the Valles Marineris, Mars, exhibit an enigmatic feature with two distinct absorptions between 2.2 and 2.3 μm. This spectral 'doublet' feature is proposed to result from a mixture of hydrated minerals, although the identity of the minerals has remained ambiguous. Here we demonstrate that similar spectral doublet features are observed in airborne, field, and laboratory reflectance spectra of rock and sediment samples from Rio Tinto, Spain. Combined visible-near infrared reflectance spectra and X-ray diffraction measurements of these samples reveal that the doublet feature arises from a mixture of Al-phyllosilicate (illite or muscovite) and jarosite. Analyses of orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) shows that the martian spectral equivalents are also consistent with mixtures of Al-phyllosilicates and jarosite, where the Al-phyllosilicate may also include kaolinite and/or halloysite. A case study for a region within Ius Chasma demonstrates that the relative proportions of the Al-phyllosilicate(s) and jarosite vary within one stratigraphic unit as well as between stratigraphic units. The former observation suggests that the jarosite may be a diagenetic (authigenic) product and thus indicative of local pH and redox conditions, whereas the latter observation may be consistent with variations in sediment flux and/or fluid chemistry during sediment deposition.

  13. Mineral resource of the month: Mica

    Willett, Jason C.

    2014-01-01

    The mica mineral group includes 34 phyllosilicate minerals, all with a layered, platy texture. The mineral has been known for millennia: Mica was first mined in India about 4,000 years ago, where it was used primarily in medicines. The Mayans used it for decorative effect in stucco to make their temples sparkle in the sun. Today it is used in everything from electrical products to makeup.

  14. Multiple techniques for mineral identification of terrestrial evaporites relevant to Mars exploration

    NASA Astrophysics Data System (ADS)

    Stivaletta, N.; Dellisanti, F.; D'Elia, M.; Fonti, S.; Mancarella, F.

    2013-05-01

    Sulfates, commonly found in evaporite deposits, were observed on Mars surface during orbital remote sensing and surface exploration. In terrestrial environments, evaporite precipitation creates excellent microniches for microbial colonization, especially in desert areas. Deposits comprised of gypsum, calcite, quartz and silicate deposits (phyllosilicates, feldspars) from Sahara Desert in southern Tunisia contain endolithic colonies just below the rock surface. Previous optical observations verified the presence of microbial communities and, as described in this paper, spectral visible analyses have led to identification of chlorophylls belonging to photosynthetic bacteria. Spectral analyses in the infrared region have clearly detected the presence of gypsum and phyllosilicates (mainly illite and/or smectite), as well as traces of calcite, but not quartz. X-ray diffraction (XRD) analysis has identified the dominant presence of gypsum as well as that of other secondary minerals such as quartz, feldspars and Mg-Al-rich phyllosilicates, such as chlorite, illite and smectite. The occurrence of a small quantity of calcite in all the samples was also highlighted by the loss of CO2 by thermal analysis (TG-DTA). A normative calculation using XRD, thermal data and X-ray fluorescence (XRF) analysis has permitted to obtain the mineralogical concentration of the minerals occurring in the samples. The combination of multiple techniques provides information about the mineralogy of rocks and hence indication of environments suitable for supporting microbial life on Mars surface.

  15. Heterogeneous material distribution, an important reason for generation of strain-localized mylonite and frictional slip zones in the Hidaka metamorphic belt, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Tanaka, Hidemi; Shimada, Koji; Toyoshima, Tsuyoshi; Obara, Tomohiro; Niizato, Tadafumi

    2004-12-01

    Lithological heterogeneity of low P/T metamorphic rocks in southern area of Hidaka metamorphic belt (HMB) was formed through historical development of HMB while these rocks had been laid in ductile lower crust. Many strain-localized mylonite zones (<100 m in thickness) are preferentially developed within S-type tonalite and pelitic gneiss, which are characterized by a large modal amount of phyllosilicates (biotite+muscovite+chlorite) and quartz, compared to other lithofacies in HMB. Mylonitic foliations are more conspicuous with close to the center of the shear zone associated with increase in amounts of phyllosilicate minerals, indicating fluidenhanced weakening mechanisms were operated in plastic shear zones. Pseudotachylyte veins are observed exclusively in these mylonite zones, which were generated during exhumation stage of HMB. We conclude the seismic slip zones in southern HMB had been initiated in the ductile lower crust by concentration of localized plastic shear zones within the phyllosilicate- and quartz-rich lithofacies, which were heterogeneously formed by old metamorphic and magmatic events. Then these zones were further weakened by fluid-enhanced plastic deformation, and finally seismic slips occurred at the bottom of seismogenic upper crust, during exhumation of HMB.

  16. Initial Estimates of Optical Constants of Mars Candidate Materials

    NASA Technical Reports Server (NTRS)

    Rousch, Ted L.; Brown, Adrian Jon; Bishop, Janice L.; Blake, David F.; Bristow, Thomas F.

    2013-01-01

    Data obtained at visible and near-infrared wavelengths by OMEGA on Mars Express and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al- OH-bearing phyllosilicates were identified including the smectites, nontronite, saponite, and montmorillonite. To constrain the abundances of these phyllosilicates, spectral analyses of mixtures are needed. We report on our effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. We include two component mixtures of hydrated/ hydroxylated silicates with each other and with two analogs for other Martian materials; pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass, hereafter referred to as palagonite). For the hydrated-hydroxylated silicates we include saponite and montmorillonite (Mg- and Al-rich smectites). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 micron.

  17. The Alteration History of Clovis Class Rocks in Gusev Crater as Determined by Ti-Normalzed Mass Balance Analysis

    NASA Technical Reports Server (NTRS)

    Sutter, Brat; Ming, Douglas W.; Niles, P. B.; Golden, D. C.

    2012-01-01

    The West Spur Clovis class rocks in Gusev Crater are some of the most altered rocks in Gusev Crater and likely contain a mixed sulfate and phyllosilicate mineralogy [1,2]. The high S and Cl content of the Clovis rocks suggests that acidic vapors or fluids of H2SO4 and HCl reacted with the Clovis parent rock to form Ca, Mg,- sulfates, iron-oxyhydroxides and secondary aluminosilicates (approx.60 wt.%) of a poorly crystalline nature (e.g., allophane) [1]. Up to 14-17 wt.% phyllosilicates (e.g., kaolinite, chlorite, serpentine) are hypothesized to exist in the Clovis materials suggesting that Clovis parent materials while possibly exposed to acidic pHs were likely neutralized by basalt dissolution which resulted in mildly acidic pHs (4-6) [1, 2]. This work proposes that subsequent to the alteration of the Clovis rocks, alteration fluids became concentrated in ions resulting in the addition of silicate and salts. The objective of this work is to utilize Ti-normalized mass balance analysis to evaluate (1) mineral gains and losses and (2) elemental gains and losses in the Clovis rocks. Results of this work will be used evaluate the nature of geochemical conditions that affect phyllosilicate and sulfate formation at Gusev crater.

  18. The central uplift of Ritchey crater, Mars

    NASA Astrophysics Data System (ADS)

    Ding, Ning; Bray, Veronica J.; McEwen, Alfred S.; Mattson, Sarah S.; Okubo, Chris H.; Chojnacki, Matthew; Tornabene, Livio L.

    2015-05-01

    Ritchey crater is a ∼79 km diameter complex crater near the boundary between Hesperian ridged plains and Noachian highland terrain on Mars (28.8°S, 309.0°E) that formed after the Noachian. High Resolution Imaging Science Experiment (HiRISE) images of the central peak reveal fractured massive bedrock and megabreccia with large clasts. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral analysis reveals low calcium pyroxene (LCP), olivine (OL), hydrated silicates (phyllosilicates) and a possible identification of plagioclase bedrock. We mapped the Ritchey crater central uplift into ten units, with 4 main groups from oldest and originally deepest to youngest: (1) megabreccia with large clasts rich in LCP and OL, and with alteration to phyllosilicates; (2) massive bedrock with bright and dark regions rich in LCP or OL, respectively; (3) LCP and OL-rich impactites draped over the central uplift; and (4) aeolian deposits. We interpret the primitive martian crust as igneous rocks rich in LCP, OL, and probably plagioclase, as previously observed in eastern Valles Marineris. We do not observe high-calcium pyroxene (HCP) rich bedrock as seen in Argyre or western Valles Marineris. The association of phyllosilicates with deep megabreccia could be from impact-induced alteration, either as a result of the Richey impact, or alteration of pre-existing impactites from Argyre basin and other large impacts that preceded the Ritchey impact, or both.

  19. Optical Constants of Mars Candidate Materials used to Model Laboratory Reflectance Spectra of Mixtures

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Brown, Adrian Jon; Blake, D.; Bristow, T.

    2014-01-01

    Data obtained at visible and nearinfrared wavelengths by OMEGA on MarsExpress and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al- OH-bearing phyllosilicates were identified including the smectites nontronite, saponite, and montmorillonite. To constrain the abundances of these phyllosilicates, spectral analyses of mixtures are needed. We report on our effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. Here we focus on two component mixtures of the hydrated/ hydroxylated silicates, saponite and montmorillonite (Mg- and Al-rich smectites) with each other and with two analogs for other Martian materials; pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass, hereafter referred to as palagonite). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 micron. Here we focus upon mixtures of the 63-90 m size fractions.

  20. Hydrothermal alteration of deep fractured granite: Effects of dissolution and precipitation

    NASA Astrophysics Data System (ADS)

    Nishimoto, Shoji; Yoshida, Hidekazu

    2010-03-01

    This paper investigates the mineralogical effects of hydrothermal alteration at depth in fractures in granite. A fracture accompanied by an alteration halo and filled with clay was found at a depth of 200 m in a drill core through Toki granite, Gifu, central Japan. Microscopic observation, XRD, XRF, EPMA and SXAM investigations revealed that the microcrystalline clays consist of illite, quartz and pyrite and that the halo round the fracture can be subdivided into a phyllic zone adjacent to the fracture, surrounded by a propylitic zone in which Fe-phyllosilicates are present, and a distinctive outer alteration front characterized by plagioclase breakdown. The processes that result in these changes took place in three successive stages: 1) partial dissolution of plagioclase with partial chloritization of biotite; 2) biotite dissolution and precipitation of Fe-phyllosilicate in the dissolution pores; 3) dissolution of K-feldspar and Fe-phyllosilicate, and illite precipitation associated with development of microcracks. These hydrothermal alterations of the granite proceed mainly by a dissolution-precipitation process resulting from the infiltration of hydrothermal fluid along microcracks. Such infiltration causes locally high mobility of Al and increases the ratio of fluid to rock in the alteration halo. These results contribute to an understanding of how granitic rock becomes altered in orogenic fields such as the Japanese island arc.

  1. Texture development in naturally compacted and experimentally deformed silty clay sediments from the Nankai Trench and Forearc, Japan

    NASA Astrophysics Data System (ADS)

    Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan H.

    2014-12-01

    The petrophysical properties of fine-grained marine sediments to a large extent depend on the microstructure and crystallographic preferred orientations (CPOs). In this contribution we show that Rietveld-based synchrotron texture analysis is a new and valuable tool to quantify textures of water-saturated fine-grained phyllosilicate-rich sediments, and assess the effects of compaction and tectonic deformation. We studied the CPO of compositionally almost homogeneous silty clay drillcore samples from the Nankai Accretionary Prism slope and the incoming Philippine Sea plate, offshore SW Japan. Basal planes of phyllosilicates show bedding-parallel alignment increasing with drillhole depth, thus reflecting progressive burial and compaction. In some samples calcite and albite display a CPO due to crystallographically controlled non-isometric grain shapes, or nannofossil tests. Consolidated-undrained experimental deformation of a suite of thirteen samples from the prism slope shows that the CPOs of phyllosilicate and calcite basal planes develop normal to the experimental shortening axis. There is at least a qualitative relation between CPO intensity and strain magnitude. Scanning electron micrographs show concurrent evolution of preferred orientations of micropores and detrital illite flakes normal to axial shortening. This indicates that the microfabrics are sensitive strain gauges, and contribute to anisotropic physical properties along with the CPO.

  2. Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres

    NASA Astrophysics Data System (ADS)

    de Sanctis, M. C.; Raponi, A.; Ammannito, E.; Ciarniello, M.; Toplis, M. J.; McSween, H. Y.; Castillo-Rogez, J. C.; Ehlmann, B. L.; Carrozzo, F. G.; Marchi, S.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; McFadden, L. A.; Pieters, C. M.; Jaumann, R.; Schenk, P.; Mugnuolo, R.; Raymond, C. A.; Russell, C. T.

    2016-08-01

    The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

  3. The central uplift of Ritchey crater, Mars

    Ding, Ning; Bray, Veronica J.; McEwen, Alfred S.; Mattson, Sarah S.; Okubo, Chris H.; Chojnacki, Matthew; Tornabene, Livio L.

    2015-01-01

    Ritchey crater is a ∼79 km diameter complex crater near the boundary between Hesperian ridged plains and Noachian highland terrain on Mars (28.8°S, 309.0°E) that formed after the Noachian. High Resolution Imaging Science Experiment (HiRISE) images of the central peak reveal fractured massive bedrock and megabreccia with large clasts. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral analysis reveals low calcium pyroxene (LCP), olivine (OL), hydrated silicates (phyllosilicates) and a possible identification of plagioclase bedrock. We mapped the Ritchey crater central uplift into ten units, with 4 main groups from oldest and originally deepest to youngest: (1) megabreccia with large clasts rich in LCP and OL, and with alteration to phyllosilicates; (2) massive bedrock with bright and dark regions rich in LCP or OL, respectively; (3) LCP and OL-rich impactites draped over the central uplift; and (4) aeolian deposits. We interpret the primitive martian crust as igneous rocks rich in LCP, OL, and probably plagioclase, as previously observed in eastern Valles Marineris. We do not observe high-calcium pyroxene (HCP) rich bedrock as seen in Argyre or western Valles Marineris. The association of phyllosilicates with deep megabreccia could be from impact-induced alteration, either as a result of the Richey impact, or alteration of pre-existing impactites from Argyre basin and other large impacts that preceded the Ritchey impact, or both.

  4. Clay Bearing Units in the Region around Mawrth Vallis: Stratigraphy, Extent, and Possible Alteration Fronts

    NASA Technical Reports Server (NTRS)

    Dobrea, E. Z. Noe; Bishop, J. L.; McKeown, N. K.; Swayze, G.; Michalski, J. R.; Poulet, F.; Bibring, J.-P.; Mustard, J. F.; Ehlmann, B. L.; Arvidson, R.; hide

    2007-01-01

    The largest exposure of phyllosilicates on Mars occurs on the highland plains around Mawrth Vallis. This exposure extends for about 300 km southward from the edge of the dichotomy boundary, covering an area greater than 200 x 300 kilometers over an elevation range of approximately 2000 meters. At least two different types of hydrated phyllosilicates (Fe/Mg-rich and Al-rich phyllosilicates) have been identified in OMEGA data based on absorption bands near 2.3 and 2.2 micrometers, respectively. These clay-bearing units are associated with layered, indurated light-toned units with complex spatial and stratigraphic relationships, and are unconfomably overlain by a darker, indurated, more heavily cratered unit. Ongoing analysis of OMEGA (approximately 1 kilometer/pixel) and CRISM multi-spectral (MSP, 200 meters/pixel) data reveal hydrated minerals with absorptions at approximately 2.2 or 2.3 micrometers in locations up to 300 kilometers away from the borders of the previously identified extent of clay-bearing units. We seek to: 1) further constrain the mineralogy of the hydrated species identified in [5], and 2) understand spatial and stratigraphic relationships between the different hydrated minerals and the cratered plains units in which they are found. In this work we perform mineralogical and stratigraphic comparisons between units to test whether these extended units may be related, in order to establish a broad zone of alteration.

  5. On-Going Laboratory Efforts to Quantitatively Address Clay Abundance on Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bishop, Janice L.; Brown, Adrian J.; Blake, David F.; Bristow, Thomas F.

    2012-01-01

    Data obtained at visible and near-infrared wavelengths by OMEGA on MarsExpress and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al-OH-bearing phyllosilicates were identified including the smectites, nontronite, saponite, and montmorillonite. In order to constrain the abundances of these phyllosilicates spectral analyses of mixtures are needed. We report on our on-going effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. We include two component mixtures of hydrated/hydroxylated silicates with each other and with two analogs for other martian materials; pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass). For the hydrated-hydroxylated silicates we include saponite and montmorillonite (Mg- and Al- rich smectites). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 µm. As the second phase of our effort we used scanning electron microscopy imaging and x-ray diffraction to characterize the grain size distribution, and structural nature, respectively, of the mixtures. Visible and near-infrared reflectance spectra of the 63-90 micrometers grain size of the mixture samples are shown in Figure 1. We discuss the results of our measurements of these mixtures.

  6. Sequestration of volatiles in the martian crust through hydrated minerals

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.; Ehlmann, B. L.; Poulet, F.; Fraeman, A. A.; Carter, J.

    2011-12-01

    The magnitude and history of volatile reservoirs is a key question in understanding Mars' evolution. The volumes of reservoirs for water through time have been estimated on the basis of morphology (e.g. Carr 1996) and modeling while the volume of active identifiable modern reservoirs such as the polar caps, the near-surface cryosphere, and the atmosphere are reasonably well known. One reservoir that has been hypothesized but not examined is the crust where water would be in the form of hydrous minerals. The OMEGA and CRISM experiments on Mars Express and Mars Reconnaissance Orbiter respectively, have shown that phyllosilicate minerals are commonly observed in the Noachian crust of Mars. Modeling has shown that depending on the location the abundance of clays and phyllosilicates can exceed 50% but more typically is less or absent, particularly in the Hesperian and younger terrains (Poulet 2007). Phyllosilicate-bearing outcrops have been observed in the deepest wall exposures of Valles Marineris (8 km below the rim) and in the central peaks of impact craters as large of 100 km. Modeling suggests that the porosity of the crust in maintained to approximate 8-10 km depth permitting the circulation of water to this depth and formation of phyllosilicate and other hydrated minerals. Based on these and other observations it is evident that at least the top 10 km of the crust can be considered to contain hydrated silicate minerals. These observations also show that phyllosilicates are globally present in Noachian crust. We use altered oceanic crust as an analog for the amount of alteration on Mars. Analyses show that the average volume fraction of hydrous phases in the lower oceanic crust is 10%. Simple calculations show this results in a water content of between 1 - 3%. If the upper 10 km of the martian crust is altered to this extent then a global equivalent thickness (GET) of water of 0.3 to 0.9 km is stored in the crust due to alteration minerals. This is comparable to

  7. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We

  8. Coeval Formation of Aqueous Minerals on Mars

    NASA Astrophysics Data System (ADS)

    Fairen, A.; Uceda, E.; Gil, C.; Palmero Rodriguez, A.; Gago-Duport, L.

    2015-12-01

    Understanding the geochemical conditions on early Mars requires an explanation for the presence of sulfates and phyllosilicates, which must be also consistent with the absence of widespread sedimentary carbonates. In addition, sulfates and phyllosilicates do not generally occur together on Mars, which has been interpreted as a marker for detached mineral formation due to differing planetary environmental conditions separated dramatically, either in time or in space. Here, thermodynamic equilibrium calculations are used to determine the stability boundaries for phyllosilicates, ferrous and ferric sulfates, carbonates and iron oxyhydroxides precipitation on early Mars, at different atmospheric CO2 pressures and both under reducing and oxidizing conditions. Results suggest that phyllosilicates formed in mildly acidic to alkaline aqueous solutions, with a pH>4 for nontronite and a pH>6 for other smectites with low content in Fe and Mg (montmorillonite, saponite). Sulfate deposition dominates in solutions moderately to highly acidic, with a pH<6 conducive to the synthesis of kieserite. In the overlapping phyllosilicates/sulfates pH range, between 4 and 6, a competition for Mg between nontronite and kieserite is expected, and the formation of nontronite would be favored in areas where SiO2 activity in surface waters was high as a result of intense weathering of the early basaltic crust. Carbonates formed at pH>6, overlapping with the synthesis of low-Fe-Mg smectites. Model calculations anticipate the co-precipitation of smectites and siderite or any alteration product that could have resulted from the later substitution of Fe in siderite, such as Mg- or Mn-carbonate, triggering a competition for Mg between magnesite and low-Fe-Mg smectites. As expected, the model does not predict coeval synthesis of carbonates and sulfates. Goethite and other oxyhydroxides precipitate at pH below 2, a range at which jarosite and goethite are the expected iron-bearing phases. These

  9. LED Die-Bonded on the Ag/Cu Substrate by a Sn-BiZn-Sn Bonding System

    NASA Astrophysics Data System (ADS)

    Tang, Y. K.; Hsu, Y. C.; Lin, E. J.; Hu, Y. J.; Liu, C. Y.

    2016-12-01

    In this study, light emitting diode (LED) chips were die-bonded on a Ag/Cu substrate by a Sn-BixZn-Sn bonding system. A high die-bonding strength is successfully achieved by using a Sn-BixZn-Sn ternary system. At the bonding interface, there is observed a Bi-segregation phenomenon. This Bi-segregation phenomenon solves the problems of the brittle layer-type Bi at the joint interface. Our shear test results show that the bonding interface with Bi-segregation enhances the shear strength of the LED die-bonding joints. The Bi-0.3Zn and Bi-0.5Zn die-bonding cases have the best shear strength among all die-bonding systems. In addition, we investigate the atomic depth profile of the deposited Bi-xZn layer by evaporating Bi-xZn E-gun alloy sources. The initial Zn content of the deposited Bi-Zn alloy layers are much higher than the average Zn content in the deposited Bi-Zn layers.

  10. Defect properties of Sn- and Ge-doped ZnTe: suitability for intermediate-band solar cells

    NASA Astrophysics Data System (ADS)

    Flores, Mauricio A.

    2018-01-01

    We investigate the electronic structure and defect properties of Sn- and Ge- doped ZnTe by first-principles calculations within the DFT+GW formalism. We find that ({{{Sn}}}{{Zn}}) and ({{{Ge}}}{{Zn}}) introduce isolated energy levels deep in the band gap of ZnTe, derived from Sn-5s and Ge-4s states, respectively. Moreover, the incorporation of Sn and Ge on the Zn site is favored in p-type ZnTe, in both Zn-rich and Te-rich environments. The optical absorption spectra obtained by solving the Bethe-Salpeter equation reveals that sub-bandgap absorptance is greatly enhanced due to the formation of the intermediate band. Our results suggest that Sn- and Ge-doped ZnTe would be a suitable material for the development of intermediate-band solar cells, which have the potential to achieve efficiencies beyond the single-junction limit.

  11. Interplay of 3 d - and 5 d -sublattice magnetism in the double perovskite substitution series La2Zn1 -xCoxIrO6

    NASA Astrophysics Data System (ADS)

    Vogl, M.; Corredor, L. T.; Dey, T.; Morrow, R.; Scaravaggi, F.; Wolter, A. U. B.; Aswartham, S.; Wurmehl, S.; Büchner, B.

    2018-01-01

    We report on the interplay of 3 d - and 5 d -sublattice magnetism in polycrystalline samples of the double perovskite substitution series La2Zn1 -xCoxIrO6 . Powder x-ray diffraction reveals no major structural changes within the series. In magnetization measurements, a gradual shift of the transition temperature from TN ≈91 K for the Co parent compound to TN ≈8.7 K for the Zn parent compound is observed. The data on the Zn-rich members of the substitution series indicate that this is accompanied by changing roles of the 3 d sublattice of Co2 + and the strongly spin-orbit coupled 5 d -sublattice of Ir4 + with its jeff=1 /2 ground state, as a function of the Co/Zn ratio. Temperature-dependent specific-heat studies revealed a reduced magnetic entropy, pointing towards a large spin-orbit coupling and orbital contribution in the system.

  12. Growth of bulk ZnO crystals by self-selecting CVT method

    NASA Astrophysics Data System (ADS)

    Fan, Long; Jiang, Tao; Xiao, TingTing; Chen, Jie; Peng, Liping; Wang, Xuemin; Yan, Dawei; Wu, Weidong

    2018-05-01

    Bulk ZnO crystals were grown by self-selecting CVT method using carbon as the transport agent. The crystal growth process took place on the top of the polycrystalline source material, and deep-red colored ZnO crystals of several millimeters were obtained. The as-grown crystals were characterized by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), Raman scattering (RS) spectroscopy, visible-near infrared (VIS-NIR) spectrophotometer and room temperature photoluminescence (PL) spectroscopy. XRD results indicate good crystallinity of the ZnO crystal. The EDS analysis shows that the crystal has a stoichiometry ratio Zn: O = 52: 48. The results suggest the existence of native defects of oxygen vacancies (OV) in the as-grown ZnO samples, which is caused by the stoichiometry shift to Zn-rich.

  13. Structure flexibility of the Cu2ZnSnS4 absorber in low-cost photovoltaic cells: from the stoichiometric to the copper-poor compounds.

    PubMed

    Choubrac, L; Lafond, A; Guillot-Deudon, C; Moëlo, Y; Jobic, S

    2012-03-19

    Here we present for the very first time a single-crystal investigation of the Cu-poor Zn-rich derivative of Cu(2)ZnSnS(4). Nowadays, this composition is considered as the one that delivers the best photovoltaic performances in the specific domain of Cu(2)ZnSnS(4)-based thin-film solar cells. The existence of this nonstoichiometric phase is definitely demonstrated here in an explicit and unequivocal manner on the basis of powder and single-crystal X-ray diffraction analyses coupled with electron microprobe analyses. Crystals are tetragonal, space group I ̅4, Z = 2, with a = 5.43440(15) Å and c = 10.8382(6) Å for Cu(2)ZnSnS(4) and a = 5.43006(5) Å and c = 10.8222(2) Å for Cu(1.71)Zn(1.18)Sn(0.99)S(4). © 2012 American Chemical Society

  14. Theoretical limits on the stability of single-phase kesterite-Cu{sub 2}ZnSnS{sub 4}

    SciT

    Sarker, Pranab; Huda, Muhammad N., E-mail: huda@uta.edu; Al-Jassim, Mowafak M.

    2015-01-21

    The single-phase stability of Cu{sub 2}ZnSnS{sub 4} (CZTS), after an intrinsic defect was incorporated in it, has been examined here for the first time based on ab initio calculations. The stability analysis of such a non-stoichiometric-defect incorporated CZTS shows that the single-phase formation is unlikely at thermodynamic equilibrium conditions. In addition, the effective growth condition of CZTS is determined and quantified for all the elements (Cu-poor, Zn-rich, Sn-poor, and S-rich) to extract maximum photovoltaic efficiency from CZTS. These conditions promote (i) spontaneous formation of Cu vacancy (V{sub Cu}), which might benefit p-type conduction, and (ii) the co-existence of ZnS whilemore » suppressing other harmful defects and secondary phases. Further, the results presented here explain the unavailability of single-phase CZTS to date.« less

  15. Ultrafast carrier dynamics in band edge and broad deep defect emission ZnSe nanowires

    NASA Astrophysics Data System (ADS)

    Othonos, Andreas; Lioudakis, Emmanouil; Philipose, U.; Ruda, Harry E.

    2007-12-01

    Ultrafast carrier dynamics of ZnSe nanowires grown under different growth conditions have been studied. Transient absorption measurements reveal the dependence of the competing effects of state filling and photoinduced absorption on the probed energy states. The relaxation of the photogenerated carriers occupying defect states in the stoichiometric and Se-rich samples are single exponentials with time constants of 3-4ps. State filling is the main contribution for probe energies below 1.85eV in the Zn-rich grown sample. This ultrafast carrier dynamics study provides an important insight into the role that intrinsic point defects play in the observed photoluminescence from ZnSe nanowires.

  16. Droplet Evolution and Refinement During Liquid-Liquid Decomposition of Zn-6 Wt Pct Bi Immiscible Alloy Under High Static Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zheng, Tianxiang; Zhong, Yunbo; Wang, Jiang; Ren, Zhongming; Ren, Weili; Lei, Zuosheng; Debray, Francois; Beaugnon, Eric; Wei, Xicheng

    2018-05-01

    In situ solidification experiments on Zn-6 wt pct Bi immiscible alloys were conducted to investigate the droplet evolution under high static magnetic fields (HSMFs). The results showed that a microstructure with extremely fine Bi-rich particles distributed in the matrix can be obtained under an HSMF of 29 T. The average diameter of the Bi-rich phase decreased with the increasing magnetic flux density. Stokes sedimentation disappeared when the HSMF was larger than 18 T. Starting at an HSMF of 18 T, Bi-rich droplets grew via pure diffusion in the liquid matrix. The HSMF decreased the spacing of the droplet arrays when the cooling rate (R) was approximately 1600 °C/min. The formation of a Zn-rich phase surrounded by a Bi-rich shell at HSMFs below 18 T, when R was approximately 60 °C/min, was attributed to the thermoelectric magnetic force.

  17. Mobility of indium on the ZnO(0001) surface

    SciT

    Heinhold, R.; Reeves, R. J.; Allen, M. W.

    2015-02-02

    The mobility of indium on the Zn-polar (0001) surface of single crystal ZnO wafers was investigated using real-time x-ray photoelectron spectroscopy. A sudden transition in the wettability of the ZnO(0001) surface was observed at ∼520 °C, with indium migrating from the (0001{sup ¯}) underside of the wafer, around the non-polar (11{sup ¯}00) and (112{sup ¯}0) sidewalls, to form a uniform self-organized (∼20 Å) adlayer. The In adlayer was oxidized, in agreement with the first principles calculations of Northrup and Neugebauer that In{sub 2}O{sub 3} precipitation can only be avoided under a combination of In-rich and Zn-rich conditions. These findings suggest that unintentionalmore » In adlayers may form during the epitaxial growth of ZnO on indium-bonded substrates.« less

  18. First-principles research on the optical and electrical properties and mechanisms of In-doped ZnO

    NASA Astrophysics Data System (ADS)

    Hou, Qingyu; Xi, Dongmin; Li, Wenling; Jia, Xiaofang; Xu, Zhenchao

    2018-05-01

    The absorption spectra and conductivity of In-doped ZnO still exhibit differences. To resolve this contradiction, the ZnO supercell models with different In doping amounts and the Zn0.9375In0.0625(Zni)0.0625O supercell model were both constructed. When the geometrical structure of all the models was optimized, the GGA + U and GGA used to calculate the energy. In the range of In doping used in this study, the formation energy of In-doped ZnO under Zn-rich conditions is lower than that under O-rich conditions, thereby implying a more stability of In-doped ZnO under Zn-rich than that under O-rich. With the increased In doping content, the volume and the formation energy of the doped system increase, the doped systems become unstable, and doping becomes difficult. Furthermore, the band gaps are narrowed, and the red shift of absorption spectrum is enhanced. In the In doping amount ranging within 0.01389-0.05556, the electron effective mass decreases first and subsequently increases, and the electron concentration increases. The mobility and conductivity also increase first and subsequently decrease. These results are in accordance with the experimental results. The volume of Zn0.9375In0.0625(Zni)0.0625O with the coexistence of In replacing Zn and interstitial Zn is large. The band gap is widened and the absorption spectrum is blue-shifted in the UV region.

  19. A simple route to alloyed quaternary nanocrystals Ag-In-Zn-S with shape and size control.

    PubMed

    Gabka, Grzegorz; Bujak, Piotr; Giedyk, Kamila; Ostrowski, Andrzej; Malinowska, Karolina; Herbich, Jerzy; Golec, Barbara; Wielgus, Ireneusz; Pron, Adam

    2014-05-19

    A convenient method of the preparation of alloyed quaternary Ag-In-Zn-S nanocrystals is elaborated, in which a multicomponent mixture of simple and commercially available precursors, namely, silver nitrate, indium(III) chloride, zinc stearate, 1-dodecanethiol, and sulfur, is used with 1-octadecene as a solvent. The formation of quaternary nanocrystals necessitates the use of an auxiliary sulfur precursor, namely, elemental sulfur dissolved in oleylamine, in addition to 1-dodecanethiol. Without this additional precursor binary ZnS nanocrystals are formed. The optimum reaction temperature of 180 °C was also established. In these conditions shape, size, and composition of the resulting nanocrystals can be adjusted in a controlled manner by changing the molar ratio of the precursors in the reaction mixture. For low zinc stearate contents anisotropic rodlike (ca.3 nm x 10 nm) and In-rich nanocrystals are obtained. This is caused by a significantly higher reactivity of the indium precursor as compared to the zinc one. With increasing zinc precursor content the reactivities of both precursors become more balanced, and the resulting nanocrystals are smaller (1.5-4.0 nm) and become Zn-rich as evidenced by transmission electron microscopy, X-ray diffraction, and energy-dispersive spectrometry investigations. Simultaneous increases in the zinc and sulfur precursor content result in an enlargement of nanocrystals (2.5 to 5.0 nm) and further increase in the molar ZnS content (up to 0.76). The prepared nanoparticles show stable photoluminescence with the quantum yield up to 37% for In and Zn-rich nanocrystals. Their hydrodynamic diameter in toluene dispersion, determined by dynamic light scattering, is roughly twice larger than the diameter of their inorganic core.

  20. Aqueous Alteration of the Grosnaja CV3 Carbonaceous Chondrite

    NASA Astrophysics Data System (ADS)

    Keller, L. P.; McKay, D. S.

    1993-07-01

    Previous petrographic studies have shown that aqueous alteration products are locally well developed in some of the CV3 falls [e.g., 1-3]. In this abstract, we describe our transmission electron microscope (TEM) study of the extent of aqueous alteration in matrix and in chondrules in the Grosnaja CV3 carbonaceous chondrite. Grosnaja is an observed fall and belongs to the oxidized subgroup of the CV chondrites [4]. We obtained fragments of Grosnaja from the Naturhistorisches Museum in Vienna. Regions of interest were extracted from polished thin sections and prepared for TEM observation by ion milling. Quantitative energy-dispersive X-ray (EDX) analyses were obtained using a JEOL 2000FX TEM equipped with a LINK thin- window EDX detector. Grosnaja has undergone aqueous alteration, which has resulted in the formation of phyllosilicates in matrix and in chondrules. The suprising result from Grosnaja is that three different types of phyllosilicates are intimately intergrown. Serpentine is the most abundant phyllosilicate in matrix and occurs as fine-grained packets along grain boundaries and as fracture-fillings and veinlets that cross cut olivine and pyroxene grains. Mixed with the serpentine are packets of fine-grained phyllosilicates with a distinct 1.4-nm basal spacing that is probably a chlorite group mineral. Rare packets of smectite occur as epitaxial intergrowths with olivine, but are not interstratified with serpentine as observed in the CI chondrites. Phyllosilicates in Grosnaja matrix occur with Mg-rich carbonates, fine-grained magnetite, chromite and pentlandite, and poorly-crystalline FeNi- oxide/hydroxides, which stain the matrix a brownish-red color. Some of the rust may be of terrestrial origin (Grosnaja fell in 1861). Although the matrix phyllosilicates are too small to obtain single-phase chemical analyses in the TEM, quantitative EDX analyses suggest that the serpentine contains significant Fe (Mg/Mg + Fe ~0.5). The serpentine/chlorite forms as an

  1. Effects of fluid-rock interaction on friction and slip stability of gouge-filled faults (Invited)

    NASA Astrophysics Data System (ADS)

    Spiers, C. J.

    2013-12-01

    Understanding the effects of fluid-rock interaction on fault friction is central not only to understanding natural seismogenesis but also to evaluating the risks of fault reactivation and induced seismicity posed by subsurface resources production and by geological storage of CO2. Microstructural studies on natural fault rocks deformed in the mid and upper crust, including those sampled in fault drilling projects, frequently show evidence for i) fluid-related reactions forming an anastomosing phyllosilicate network, ii) pressure solution and cataclasis of clast phases, and iii) dilatation and cementation of fractures, cracks and pores. Moreover, decades of friction experiments on simulated granitic, gabroic, quartz and more recently calcite and phyllosilicate-quartz gouges, have shown that the presence of an aqueous pore fluid, or even water vapour, strongly influences the frictional behaviour of these materials. This has long been recognised to point to the operation of fluid-assisted deformation mechanisms, such as stress corrosion cracking or pressure solution. Indeed, recent low velocity friction experiments performed at Utrecht on evaporite and quartz gouges, with varying amounts of phyllosilicate, indicate that fluid-assisted deformation of the clast phases is a requirement for velocity-weakening slip capable of causing stick-slip. Supercritical carbon dioxide, on the other hand, has little effect on the frictional behaviour of either dry or wet gouges. An important trend emerging from all gouges containing quartz, and tested at hydrothermal conditions and sliding velocities below 100 μm/s, is a transition from velocity strengthening at low temperatures, to velocity weakening at intermediate temperatures, and back to velocity strengthening at high temperatures, delineating three regimes of steady state frictional behaviour. Where dilation has been measured or estimated, the velocity weakening regime is further characterised by porosity development. This all

  2. Recent Opportunity Microscopic Imager Results

    NASA Astrophysics Data System (ADS)

    Herkenhoff, K. E.; Arvidson, R. E.; Jolliff, B. L.; Yingst, R.; Team, A.

    2013-12-01

    Opportunity arrived at exposures of Endeavour crater rim rocks in August 2011, on a hill dubbed 'Cape York.' These rocks have been the goal of exploration by Opportunity for the past few years because spectral evidence for phyllosilicates was observed at this location in orbital remote sensing data. As Opportunity circum¬navigated Cape York, the Microscopic Imager (MI) was used to examine the fine-scale textures of various soils and rocky outcrops. As reported previously, Opportunity discovered multiple bright linear features along the western periphery of Cape York that have been interpreted as veins of Ca sulfate deposited in fractures within the bedrock of Cape York. Opportunity then explored the northern and eastern sides of Cape York, including the area around 'Matijevic Hill' that shows evidence for phyllosilicates in CRISM data acquired from the Mars Reconnaissance Orbiter. One of the first outcrops examined near Matijevic Hill, dubbed 'Kirkwood,' is dominated by millimeter-size spherules. Unlike the hematite-rich concretions observed by Opportunity on Meridiani Planum, the aggregated 'newberries' in the Kirkwood exposure display internal structure and resistant rims. Compositionally, the spherule-rich rock is very similar to a nearby spherule-poor outcrop dubbed 'Whitewater Lake.' Thus these spherules have a more basalt-like composition compared to the hematite-rich concretions of the Burns Formation. The origin of the Kirkwood outcrop is uncertain, but the setting on the rim of the 22-km diameter Endeavour crater suggests that perhaps impact melting was involved in lapilli formation, possibly followed by mobilization and sorting in the ejecta blanket. Alternatively, the newberries may be diagenetic iron oxide concretions that are less well cemented than the 'blueberries' of the younger sulfate-rich Burns Formation. The Whitewater Lake outcrops contain the phyllosilicate phases observed from orbit, and are the oldest materials yet investigated by

  3. Experimental Alteration of Basalt to Support Interpretation of Remote Sensing and In Situ Meausrements from Mars

    NASA Technical Reports Server (NTRS)

    Bell, M. S.

    2014-01-01

    Major occurrences of hydrous alteration minerals on Mars have been found in Noachian impact craters formed in basaltic targets and detected using visible/near infrared (VNIR) spectroscopy. Until recently phyllosilicates were detected only in craters in the southern hemisphere [1, 2]. However, it has been reported that at least nine craters in the northern plains apparently excavated thick layers of lava and sediment to expose phyllosilicates [3] as well. The MER (Mars Exploration Rovers) rovers previously reported results of in situ measurement indicating the presence of alteration minerals on Mars [4,5] and it was recently reported that the Mars Curiosity rover has detected alteration phases in situ at Yellowknife Bay in Gale crater as well [6,7]. An important discovery for Mars geochronology is that the Chemistry and Mineralogy (CheMin) x-ray diffraction (XRD) instrument on Curiosity detected phyllosilicates indicating that phyllosilicate formation on Mars extended beyond the Noachian Epoch [8]. These discoveries indicate that Mars was globally altered by water in the past but does not constrain formation conditions for alteration phase occurrences, which have important implications for the evolution of the surface and the biological potential on Mars. Understanding the alteration assemblages produced by a range of conditions is vital for the interpretation of phyllosilicate spectral signatures as well as in situ measurements and to decipher the environment and evolution of early Mars. The martian surface has been intensely altered by meteorite impacts whose effects include brecciation and melting of target materials as well as the initiation of hydrothermal circulation in a hydrous target [9,10,11,12]. Impact effects may facilitate aqueous alteration of a basaltic target because the rate of silicate dissolution is a function of the degree of crystallinity, surface area, and temperature. The resultant alteration mineralogies from shocked basaltic target material

  4. Systematic variations in the spectral properties of bright regions on Mars

    NASA Technical Reports Server (NTRS)

    Murchie, Scott; Mustard, John; Bishop, Janice; Head, James; Pieters, Carle; Erard, Stephane

    1992-01-01

    The color and albedo of the martian surface define two basic surface units, dark gray material interpreted as relatively unaltered 'rock' and bright reddish material interpreted as weathered 'soil'. Understanding the processes contributing to soil formation first requires assessment of the soil's composition and compositional diversity. We report first results of an investigation of the character and variability of Fe- and water-bearing phases in bright reddish materials using ISM data. We also explore implications of these results for chemical evolution of martian soil. Information on the composition and distribution of bright reddish material comes from three major sources: Viking images, measurements by the XRF and GCMS instruments on the Viking Landers, and spectroscopic data. The XRF experiment found nearly identical, Fe-rich major-element compositions comparable to weathered basalt. Soil water, amounting to approximately 1-3 wt. percent as measured by the GCMS, was liberated mostly by heating to greater than or equal to 350 C, suggesting that it is present in a chemically bound form. Spectroscopic studies have detected ferric oxide, probably hematite, as well as molecular water. However, the identities of major silicate phases have been controversial, with conflicting evidence regarding phyllosilicates. Two main interpretations of this evidence have been proposed: Weathering of basaltic glasses by H2O and CO2 formed a mixture of oxides, salts, and metastable phyllosilicates such as montmorillonite and 'palagonite' formed when basaltic melt contacted ground ice or water. Palagonite is a hydrated basaltic glass containing dispersed ferric oxide, recrystallized in varying degrees to phyllosilicates. Typically it is aphanitic, although some examples contain phenocrysts. In either case, eolian redistribution is thought to have resulted in the material's global homogenization. Imaging spectroscopic data returned by the ISM instrument on Phobos 2 provide a powerful

  5. Negative Searches for Evidence of Aqueous Alteration on Asteroid Surfaces

    NASA Technical Reports Server (NTRS)

    Vilas, F.

    2005-01-01

    Small bodies in the Solar System preserve evidence of the processes occurring during early Solar System formation, unlike the larger planets that undergo continuous churning of their surfaces. We study these bodies to understand what processes affected different stages of Solar System formation. The action of aqueous alteration (the alteration of material by the interaction of that material with liquid formed by the melting of incorporated ice) of near-subsurface material has been inferred to occur on many asteroids based on the spectrophotometric evidence of phyllosilicates and iron alteration minerals. The definitive indication of aqueous alteration is the 3.0- micron absorption feature attributed to structural hydroxyl (OH) and interlayer and adsorbed water (H2O) in phyllosilicates (clays) (hereafter water of hydration). A weak absorption feature centered near 0.7 microns attributed to an Fe (2+) right arrow Fe (3+) charge transfer transition in oxidized iron in phyllosilicates has been observed in the reflectance spectra and photometry of approximately 50% of the main-belt C-class asteroids. An approximately 85% correlation between this 0.7- micron feature and the 3.0- micron water of hydration absorption feature was found among the low-albedo asteroids. The feature is usually centered near 0.68 microns in asteroid spectra, and ranges in wavelength from approximately 0.57 to 0.83 microns. Serendipitously, three of the Eight Color Asteroid Survey filters the v (0.550 microns), w (0.701 microns), and x (0.853 microns)-bracket this feature well, and can be used to determine the presence of this feature in the reflectance properties of an asteroid, and probe the aqueous alteration history of larger samples of asteroid data. Two efforts to search for evidence of aqueous alteration based on the presence of this 0.7- micron absorption feature are presented here.

  6. Discovery of jarosite within the Mawrth Vallis region of Mars: Implications for the geologic history of the region

    NASA Astrophysics Data System (ADS)

    Farrand, William H.; Glotch, Timothy D.; Rice, James W.; Hurowitz, Joel A.; Swayze, Gregg A.

    2009-12-01

    Analysis of visible to near infrared reflectance data from the MRO CRISM hyperspectral imager has revealed the presence of an ovoid-shaped landform, approximately 3 by 5 km in size, within the layered terrains surrounding the Mawrth Vallis outflow channel. This feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite, specifically a K-bearing jarosite (KFe 3(SO 4) 2(OH) 6). Terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur. Previously identified phyllosilicates in the Mawrth Vallis layered terrains include a basal sequence of layers containing Fe-Mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates. In terms of its fine scale morphology revealed by MRO HiRISE imagery, the jarosite-bearing unit has fracture patterns very similar to that observed in Fe-Mg smectite-bearing layers, but unlike that observed in the Al-bearing phyllosilicate unit. The ovoid-shaped landform is situated in an east-west bowl-shaped depression superposed on a north sloping surface. Spectra of the ovoid-shaped jarosite-bearing landform also display an anomalously high 600 nm shoulder, which may be consistent with the presence of goethite and a 1.92 μm absorption which could indicate the presence of ferrihydrite. Goethite, jarosite, and ferrihydrite can be co-precipitated and/or form through transformation of schwertmannite, both processes generally occurring under low pH conditions (pH 2-4). To date, this location appears to be unique in the Mawrth Vallis region and could represent precipitation of jarosite in acidic, sulfur-rich ponded water during the waning stages of drying.

  7. Mineralogy and stratigraphy of the Gale crater rim, wall, and floor units

    NASA Astrophysics Data System (ADS)

    Buz, Jennifer; Ehlmann, Bethany L.; Pan, Lu; Grotzinger, John P.

    2017-05-01

    The Curiosity rover has detected diverse lithologies in float rocks and sedimentary units on the Gale crater floor, interpreted to have been transported from the rim. To understand their provenance, we examine the mineralogy and geology of Gale's rim, walls, and floor, using high-resolution imagery and infrared spectra. While no significant differences in bedrock spectral properties were observed within most Thermal Emission Imaging System and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) scenes, some CRISM scenes of rim and wall rocks showed olivine-bearing bedrock accompanied by Fe/Mg phyllosilicates. Hydrated materials with 2.48 μm absorptions in Gale's eastern walls are spectrally similar to the sulfate unit in Mount Sharp (Aeolis Mons). Sedimentary strata on the Gale floor southwest of the landing site, likely coeval with the Bradbury units explored by Curiosity, also are hydrated and/or have Fe/Mg phyllosilicates. Spectral properties of these phyllosilicates differ from the Al-substituted nontronite detected by CRISM in Mount Sharp, suggesting formation by fluids of different composition. Geologic mapping of the crater floor shows that the hydrated or hydroxylated materials are typically overlain by spectrally undistinctive, erosionally resistant, cliff-forming units. Additionally, a 4 km impact crater exposes >250 m of the Gale floor, including finely layered units. No basement rocks are exposed, thus indicating sedimentary deposits ≥250 m beneath strata studied by Curiosity. Collectively, the data indicate substantial sedimentary infill of Gale crater, including some materials derived from the crater rim. Lowermost thin layers are consistent with deposition in a lacustrine environment; interbedded hydrated/hydroxylated units may signify changing environmental conditions, perhaps in a drying or episodically dry lake bed.

  8. The Valence of Iron in CM Chondrite Serpentine as Measured by Synchrotron Xanes

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Zolensky, Michael E.; Satake, W.; Le, L.

    2012-01-01

    Fe-bearing phyllosilicates are the dominant product of aqueous alteration in carbonaceous chondrites, and serpentine is the most abundant phyllosilicate in CM2 chondrites that are the most abundant carbonaceous chondrite. Browning et al. predicted that Fe(3+)/(sum of Fe) ratios of serpentine in CM chondrites should change with progressive alteration. They proposed that progressive CM alteration is best monitored by evaluating the progress of Si and Fe3+ substitutions that necessarily attend the transition from end-member cronstedtite to serpentine. Their proposed Mineralogic Alteration Index, 2-(Fe(3+)/(2-Si)), was intended to highlight and utilize the relevant ex-change information in the stoichiometric phyllosilicate formulas based upon the coupled substitution of 2(Fe(3+), Al) = Si + (Mg, Fe(2+)...) in serpentine. The value of this ratio increases as alteration proceeds. We always wanted to directly test Browning s pre-diction through actual measurements of the Fe3+ con-tent of serpentine at the micron scale appropriate to EPMA analyses (Zega et al. have measured it at much finer scale), and this test can now be made using Synchrotron Radiation X-ray Absorption Near-Edge Structure (SR-XANES). Thus, we have recently begun investigation with CMs that span a large portion of the range of observed aqueous alteration, and we first analyzed Murray, Nogoya, and ALH84029 by SR-XANES. However, we did not find clear correlation between Fe3+/(sum of Fe) ratios of serpentine and their alteration degrees. We thus analyzed serpentine in three more CMs and here report their Fe3+/(sum of Fe) ratios in comparison with our previous results.

  9. Discovery of jarosite within the Mawrth Vallis region of Mars: Implications for the geologic history of the region

    Farrand, W. H.; Glotch, T.D.; Rice, J. W.; Hurowitz, J.A.; Swayze, G.A.

    2009-01-01

    Analysis of visible to near infrared reflectance data from the MRO CRISM hyperspectral imager has revealed the presence of an ovoid-shaped landform, approximately 3 by 5 km in size, within the layered terrains surrounding the Mawrth Vallis outflow channel. This feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite, specifically a K-bearing jarosite (KFe3(SO4)2(OH)6). Terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur. Previously identified phyllosilicates in the Mawrth Vallis layered terrains include a basal sequence of layers containing Fe-Mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates. In terms of its fine scale morphology revealed by MRO HiRISE imagery, the jarosite-bearing unit has fracture patterns very similar to that observed in Fe-Mg smectite-bearing layers, but unlike that observed in the Al-bearing phyllosilicate unit. The ovoid-shaped landform is situated in an east-west bowl-shaped depression superposed on a north sloping surface. Spectra of the ovoid-shaped jarosite-bearing landform also display an anomalously high 600 nm shoulder, which may be consistent with the presence of goethite and a 1.92 ??m absorption which could indicate the presence of ferrihydrite. Goethite, jarosite, and ferrihydrite can be co-precipitated and/or form through transformation of schwertmannite, both processes generally occurring under low pH conditions (pH 2-4). To date, this location appears to be unique in the Mawrth Vallis region and could represent precipitation of jarosite in acidic, sulfur-rich ponded water during the waning stages of drying. ?? 2009 Elsevier Inc. All rights reserved.

  10. Surviving High-temperature Components in CI Chondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, M.; Frank, D.

    2014-01-01

    The CI1 chondrites, while having the most solar-like compo-sition of any astromaterial available for laboratory analysis, have also been considerably altered by asteroidal processes including aqueous alteration. It is of fundamental importance to determine their pre-alteration mineralogy, so that the state of matter in the early Solar System can be better determined. In the course of a re-examination of the compositional range of olivine and low-Ca pyroxene in CI chondrites Orgueil, Ivuna and Alais [1] we found the first reported complete CAI, as already reported [2], with at-tached rock consisting mainly of olivine and low-Ca pyroxene. The range of residual olivine major element compositions we have determined in the CIs (Fig. 1) may now be directly com-pared with those of other astromaterials, including Wild 2 grains. The abundance of olivine and low-Ca pyroxene in CIs is higher than is generally appreciated, and in fact much higher than for some CMs [1]. We also noted numerous rounded objects varying in shape from spheres to oblate spheroids, and ranging up to 100µm in size (Fig. 2), which have been previously noted [3] but have not been well documented or appreciated. We characterized the mineralogy by transmission electron microscopy and found that they consist mainly of rather fine-grained, flaky single phase to intergrown serpentine and saponite. These two materials in fact dominate the bulk of the host CI1 chondrites. With the exception of sparse spinels, the rounded phyllosilicate objects are remarka-bly free of other minerals, suggesting that the precursor from which the phyllosilicates were derived was a homogeneous mate-rial. We suggest that these round phyllosilicates aggregates in CI1 chondrites were cryptocrystalline to glassy microchondrules. If so then CI chondrites cannot be considered chondrule-free. Small though they are, the abundance of these putative microchondrules is the same as that of chondrules in the Tagish Lake meteorite.

  11. Detailed spectroscopic analysis of chloride salt deposits in Terra Sirenum, Mars

    NASA Astrophysics Data System (ADS)

    Osterloo, M. M.; Glotch, T. D.; Bandfield, J. L.

    2015-12-01

    Chloride salt-bearing deposits have been identified throughout the southern highlands of Mars [1] based on the lack of diagnostic spectral features of anhydrous chlorides in both the visible near infrared (VNIR) and middle infrared (MIR) wavelength ranges [1,2]. A puzzling aspect of martian chloride deposits is the apparent lack of other weathering or evaporite phases associated with most of the deposits. A global analysis over the chloride salt sites conducted by [3] found that only ~9% of the deposits they analyzed were associated with minerals such as phyllosilicates. Most of these occurrences are in Terra Sirenum where [4] noted that salt-bearing deposits lie stratigraphically above Noachian phyllosilicates. Although a variety of formation mechanisms have been proposed for these intriguing deposits, detailed geologic mapping by [5] suggests that surface water and evaporation played a dominant role. On Earth, evaporative settings are often characterized by a multitude of evaporite and phyllosilicate phases including carbonates, sulfates, and nitrates. [6] evaluated chemical divides and brine evolution for martian systems and their results indicate three pathways wherein late-stage brines favor chloride precipitation. In each case the pathway to chloride formation includes precipitation of carbonates (calcite, siderite, and/or magnesite) and sulfates (gypsum, melanterite, and/or epsomite). Here, we present the results of our detailed and systematic spectroscopic study to identify additional evaporite phases associated with salt/silicate mixtures in Terra Sirenum. [1] Osterloo et al. (2008) Science, 319, [2] Glotch, T. D. et al. (2013) Lunar and Planet. Sci. XLIV, abstract #1549 [3] Ruesch, O. et al. (2012), J. Geophys. Res., 117, E00J13 [4] Glotch, T. D. et al. (2010) Geophys. Res. Lett. 37, L16202, [5] Osterloo, M. M. and B. M Hynek (2015) Lunar and Planet. Sci XLVI. Abstract #1054 [6] Tosca, N. J. and S. M. McLennan (2006), Earth and Planet. Sci. Lett., 241.

  12. Visible Wavelength Spectroscopy of Ferric Minerals: A Key Tool for Identification of Ancient Martian Aqueous Environments

    NASA Technical Reports Server (NTRS)

    Murchie, Scott L.; Bell, J. F., III; Morris, Richard V.

    2000-01-01

    The mineralogic signatures of past aqueous alteration of a basaltic Martian crust may include iron oxides and oxyhydroxides, zeolites, carbonates, phyllosilicates, and silica. The identities, relative abundances, and crystallinities of the phases formed in a particular environment depend on physicochemical conditions. At one extreme, hot spring environments may be characterized by smectite-chlorite to talc-kaolinite silicate assemblages, plus crystalline ferric oxides dominated by hematite. However, most environments, including cold springs, pedogenic layers, and ponded surface water, are expected to deposit iron oxides and oxyhydroxides, carbonates, and smectite-dominated phyllosilicates. A substantial fraction of the ferric iron is expected to occur in nanophase form, with the exact mineralogy strongly influenced by Eh-pH conditions. Detection of these phases has been an objective of a large body of terrestrial telescopic, Mars orbital, and landed spectral investigations and in situ compositional measurements. However, clear identifications of many of these phases is lacking. Neither carbonate nor silica has been unequivocally detected by any method. Although phyllosilicates may occur near the limit of detection by remote sensing, in general they appear to occur in only poorly crystalline form. In contrast, compelling evidence for ferric iron minerals has been gathered by recent telescopic investigations, the Imager for Mars Pathfinder (IMP), and the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor (MGS). These data yield two crucial findings: (1) In the global, high spatial resolution TES data set, highly crystalline ferric iron (as coarse-grained 'gray' hematite) has been recognized but with only very limited spatial occurrence and (2) Low-resolution telescopic reflectance spectroscopy, very limited orbital reflectance spectroscopy, and landed multispectral imaging provide strong indications that at least two broad classes of ferric iron minerals

  13. Mars Exploration Rover APXS Results from Matijevic Hill

    NASA Technical Reports Server (NTRS)

    Cohen, B. A.; Clark, B. C.; Gellert, R.; Klingelhoefer, G.; Ming, D. W.; Mittlefehldt, D. W.; Morris, R. V.; Schrader, C. M.; Schroeder, C.; Yen, A. S.; hide

    2013-01-01

    Correlation analysis of APXS results on the eastern slope rocks indicate that the Matijevic Hill rocks are overall compositionally distinct from the Shoemaker Formation rocks [6]. Compared to the Shoemaker impactites, Matijevic Hill rocks are higher in Al, Si, and Ni, and lower in Ti, Fe, and Zn. No significant variation is evident in the APXS analyses that indicate the presence of a smectite or other phyllosilicate, as opposed to basaltic rocks. However, APXS data cannot in themselves rule out phyllosilicates. If indeed this material contains smectite, as seen from orbit, it implies that the rock has been isochemically altered to create the phyllosilicate content. The Cl content of the Cape York rocks is relatively high, and whereas the S/Cl ratio in the Burns Formation is 4x higher than in soil, in the Cape York rocks it is lower than in soil. These trends indicate that the alteration processes and types of aqueous salt loads were different between Cape York and Meridiani. In addition, significant deviations from the Martian Mn/Fe ratio are observed in Whitewater Lake coatings and the altered Grasford/Deadwood rocks (Fig. 3). These variations indicate that the redox/pH conditions during alteration of the Shoemaker Formation rocks and the Matijevic Hill rocks were similar, but that the Deadwood/Grasberg unit may have undergone alteration under different conditions, possibly at a later time. The Matijevic Hill outcrops appear to share a common genetic origin. It is not yet clear whether both the Shoemaker impactites and Matijevic Hill rocks are related to the formation of Endeavour Crater, or whether the Matijevic Hill suite represents a prior episode of Martian impact or volcanism. Opportunity continues to investigate both hypotheses.

  14. Alteration processes in volcanic soils and identification of exobiologically important weathering products on Mars using remote sensing.

    PubMed

    Bishop, J L; Froschl, H; Mancinelli, R L

    1998-12-25

    Determining the mineralogy of the Martian surface material provides information about the past and present environments on Mars which are an integral aspect of whether or not Mars was suitable for the origin of life. Mineral identification on Mars will most likely be achieved through visible-infrared remote sensing in combination with other analyses on landed missions. Therefore, understanding the visible and infrared spectral properties of terrestrial samples formed via processes similar to those thought to have occurred on Mars is essential to this effort and will facilitate site selection for future exobiology missions to Mars. Visible to infrared reflectance spectra are presented here for the fine-grained fractions of altered tephra/lava from the Haleakala summit basin on Maui, the Tarawera volcanic complex on the northern island of New Zealand, and the Greek Santorini island group. These samples exhibit a range of chemical and mineralogical compositions, where the primary minerals typically include plagioclase, pyroxene, hematite, and magnetite. The kind and abundance of weathering products varied substantially for these three sites due, in part, to the climate and weathering environment. The moist environments at Santorini and Tarawera are more consistent with postulated past environments on Mars, while the dry climate at the top of Haleakala is more consistent with the current Martian environment. Weathering of these tephra is evaluated by assessing changes in the leachable and immobile elements, and through detection of phyllosilicates and iron oxide/oxyhydroxide minerals. Identifying regions on Mars where phyllosilicates and many kinds of iron oxides/oxyhydroxides are present would imply the presence of water during alteration of the surface material. Tephra samples altered in the vicinity of cinder cones and steam vents contain higher abundances of phyllosilicates, iron oxides, and sulfates and may be interesting sites for exobiology.

  15. Relationships Among Intrinsic Properties of Ordinary Chondrites: Oxidation State, Bulk Chemistry, Oxygen-isotopic Composition, Petrologic Type, and Chondrule Size

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    2006-01-01

    The properties of ordinary chondrites (OC) reflect both nebular and asteroidal processes. OC are modeled here as having acquired nebular water, probably contained within phyllosilicates, during agglomeration. This component had high Ai70 and acted like an oxidizing agent during thermal metamorphism. The nebular origin of this component is consistent with negative correlations in H, L, and LL chondrites between oxidation state (represented by olivine Fa) and bulk concentration ratios of elements involved in the metal-silicate fractionation (e.g., NdSi, Ir/Si, Ir/Mn, Ir/Cr, Ir/Mg, Ni/Mg, As/Mg, Ga/Mg). LL chondrites acquired the greatest abundance of phyllosilicates with high (delta)O-17 among OC (and thus became the most oxidized group and the one with the heaviest O isotopes); H chondrites acquired the lowest abundance, becoming the most reduced OC group with the lightest O isotopes. Chondrule precursors may have grown larger and more ferroan with time in each OC agglomeration zone. Nebular turbulence may have controlled the sizes of chondrule precursors. H-chondrite chondrules (which are the smallest among OC) formed from the smallest precursors. In each OC region, low-FeO chondrules formed before high-FeO chondrules during repeated episodes of chondrule formation. During thermal metamorphism, phyllosilicates were dehydrated; the liberated water oxidized metallic Fe-Ni. This caused correlated changes with petrologic type including decreases in the modal abundance of metal, increases in olivine Fa and low-Ca pyroxene Fs, increases in the olivine/pyroxene ratio, and increases in the kamacite Co and Ni contents. As water (with its heavy 0 isotopes) was lost during metamorphism, inverse correlations between bulk (delta)O-18 and bulk (delta)O-17 with petrologic type were produced. The H5 chondrites that were ejected from their parent body approx.7.5 Ma ago during a major impact event probably had been within a few kilometers of each other since they accreted approx.4

  16. Mineral and whole-rock compositions of seawater-dominated hydrothermal alteration at the Arctic volcanogenic massive sulfide prospect, Alaska

    Schmidt, J.M.

    1988-01-01

    The Arctic volcanogenic massive sulfide prospect, located in the Ambler mineral district of northwestern Alaska, includes three types of hydrothermally altered rocks overlying, underlying, and interlayered with semimassive sulfide mineralization. Hydrothermal alteration of wall rocks and deposition of sulfide and gangue minerals were contemporaneous with Late Devonian of Early Mississippian basalt-rhyolite volcanism. Alteration developed asymmetrically around a linear fissure, suggesting fracture control of ore fluids rather than a point source. Microprobe analyses of phyllosilicates from the Arctic area indicate two discrete mineral populations. These differences in mineral chemistry are the result of differences in protolith composition caused by hydrothermal alteration-metasomatism. -from Author

  17. Stable isotopic evidence for fluid flow and fluid/rock interaction during thrust faulting in Pumpkin Valley shale and Rome Formation, east Tennessee

    SciT

    Butler, B.K.; Haase, C.S.

    1989-08-01

    The Pumpkin Valley Shale and the underlying Rome Formation form the lower portions of the Copper Creek and White Oak Mountain thrust sheets in east Tennessee. The Pumpkin Valley Shale consists of shale and mudstone with subordinate amounts of interbedded siltstone. The Rome Formation is composed predominantly of sandstone with interbedded shale and siltstone toward the base of the formation. The percentage of illite increases from 20% to over 80% of the bulk clay mineralogy toward the base of the section. Porosity is occluded by quartz, phyllosilicate, and calcite cements. Both formations contain calcite-filled and, less commonly, quartz-filled Alleghenian fracturesmore » and joints.« less

  18. Recent Opportunity Microscopic Imager Results from the Western Rim of Endeavour Crater

    NASA Astrophysics Data System (ADS)

    Herkenhoff, K. E.; Arvidson, R. E.; Jolliff, B. L.; Mittlefehldt, D. W.; Sullivan, R. J., Jr.; Gellert, R.; Sims, M. H.

    2016-12-01

    The Athena science payload on the Mars Exploration Rover Oppor­tunity includes the Microscopic Imager (MI), a fixed-focus close-up camera mounted on the instrument arm. The MI acquires images at a scale of 31 µm/pixel over a broad spectral range (400 to 700 nm) using only natural illumination of target surfaces. Opportunity has been exploring exposures of Noachian-age rocks along the rim of Endeavour crater since August 2011, moti­vated by orbital spectral evidence for phyllosilicates at multiple locations along the crater's rim. Because Opportunity can no longer directly sense phyllosilicate mineralogy with the MiniTES or Mössbauer spectrometers, the rover mis­sion is focusing on characterizing outcrop multispectral reflectance with Pancam, elemental chemistry with the Alpha Particle X-ray Spectrometer (APXS) and microtexture with the MI of potential phyllosilicate host rocks. In addition, the Rock Abrasion Tool (RAT) gives an indication of rock hardness. After traversing more than 42 km (26 miles) since landing in 2004, the rover entered "Marathon Valley" to investigate rock exposures in which phyllosili­cates were detected by the CRISM instrument on the Mars Reconnaissance Orbiter. Where clastic textures are resolved, the outcrop pavement in Marathon Valley consists of poorly-sorted dark, sub-rounded to sub-angular clasts in a soft (based on RAT grind data), fine-grained, brighter matrix (see Figure showing 5x5 cm post-grind MI mosaic of "Pierre Pinaut3," acquired on Sol 4373 when target was fully shadowed). These observations are consistent with high-energy emplacement due to impact cratering. The soft, recessive, altered appearance of the matrix material suggests that it is the likely host of phyllosilicate alteration in these rocks. The bedrock appears to have been aqueously altered, but APXS measurements of major elements indicate that the alteration was isochemical, unlike in other Endeavour rim rocks. Also, MI views of a small patch of dark sand

  19. Oxidation of Structural Fe(II) in Biotite by Lithotrophic Fe(II)-oxidizing microorganisms

    NASA Astrophysics Data System (ADS)

    Shelobolina, E.; Blöthe, M.; Xu, H.; Konishi, H.; Roden, E.

    2008-12-01

    The potential for microbial involvement in the oxidation of Fe(II)-bearing phyllosilicates is an understudied aspect of soil/sediment Fe biogeochemistry. An important property of structural Fe in Fe-bearing smectites is their ability to undergo multiple redox cycles without being mobilized. An obvious choice of mineral substrate for enumeration/isolation of Fe(II)-oxidizing microorganisms would be reduced smectite. But reduced smectite is readily oxidized by air. That is why biotite was chosen as a substrate for this study. In contrast to smectite, biotite is more stable in the presence of air, but incapable of redox cycling. Once Fe(II) is oxidized, biotite is weathered to expendable 2:1 phyllosilicates or kaolinite. First, we evaluated the ability of a neutral-pH lithoautotrophic nitrate-reducing enrichment culture (MPI culture), recovered by Straub et al (Appl. Environ. Microbiol., 1996, 62:1458-1460) from a freshwater ditch, to oxidize two different specimens of biotite. The culture was capable of multiple transfers in anaerobic nitrate-containing biotite suspensions. The growth of MPI culture resulted in decrease of 0.5 N HCl-extractable Fe(II) content and simultaneous nitrate reduction. Cell yields were comparable to those observed for other neutral-pH lithoautotrophic Fe(II)-oxidizing bacteria. High resolution TEM examination revealed structural and chemical changes at the edges of oxidized biotite and formation of reddish amorphous precipitates dominated by Si and Fe. To further evaluate efficiency of biotite for recovery of oxygen- and nitrate-dependent Fe(II) oxidizing cultures microbial enumeration study was performed using subsoil from a site near Madison, WI. The soil is rich in Fe-bearing smectite and shows evidence of redoximorphic features. The enumeration of Fe(II) oxidizing organisms from this sediment showed 10-fold higher efficiency of biotite over soluble Fe(II) for recovery of Fe(II)-oxidizers. Isolation and identification of both aerobic and

  20. Curiosity Rover's CheMin Instrument Investigates Mineralogy of Gale Crater and Implications for Diagenesis

    NASA Astrophysics Data System (ADS)

    Fendrich, Kim; Rampe, Elizabeth; Vaniman, David; Bish, David; Blake, David; Treiman, Allan; Ming, Doug; Morris, Richard; Bristow, Tom; Cavanagh, Patrick; Downs, Robert; Morrison, Shaunna; Chipera, Steve; Achilles, Cherie; Farmer, Jack; Sarrazin, Philippe; Crisp, Joy; Morookian, John Michael; Yen, Albert; Gellert, Ralf

    2015-04-01

    The Mars Science Laboratory rover Curiosity employs a suite of instruments to investigate past or present habitability of Mars, as observed at Gale crater and particularly in the lower strata of the crater's central mound, informally named Mount Sharp. The X-ray diffractometer on board, CheMin, is used to assess the quantitative mineralogy of scooped soil samples and drilled rock powders. Methods of modeling diffraction peak positions and intensities to evaluate the abundances of minerals include Rietveld refinement and FULLPAT (full-pattern fitting). Each of the samples analyzed by CheMin contains X-ray amorphous material. The amorphous component chemistry is resolved by subtracting the chemistry of the crystalline composition, as determined by X-ray diffraction data, from the bulk sample chemistry, as determined by the Alpha Particle X-ray Spectrometer (APXS). Diffraction results have been obtained on five samples thus far to include Rocknest, John Klein, Cumberland, Windjana and Confidence Hills. Soil samples collected at Rocknest, an aeolian bedform in Gale crater, were the first to be analyzed in situ by CheMin. The Rocknest mineral assemblage is basaltic (plagioclase, Fe-forsterite, augite, pigeonite) and contains amorphous material that is compositionally similar to palagonitic volcanic soils found on Earth, with the addition of sulfur and chlorine. The four drill analyses are characteristic of deposition in a variety of fluvio-lacustrine environments and exhibit evidence of low-temperature diagenesis. Both John Klein and Cumberland are part of the Sheepbed mudstone at Yellowknife Bay, where the first drilled samples were acquired as well as the first evidence of a habitable environment on Mars. Drilled three meters apart from each other, the two samples reveal basaltic minerals similar to those at Rocknest, as well as phyllosilicates, Fe-oxides/hydroxides, Ca-sulfates, Fe-sulfides, and amorphous materials. The nature and hydration of interlayer cations

  1. Deep Hydrothermal Circulation and Implications for the Early Crustal Compositional and Thermal Evolution of Mars

    NASA Astrophysics Data System (ADS)

    Parmentier, E. M.; Mustard, J. F.; Ehlmann, B. L.; Roach, L. H.

    2007-12-01

    Both orbital remote sensing and geophysical observations indicate an important role for hydrothermal crustal cooling during the Noachian epoch. Orbital remote sensing shows that phyllosilicate minerals are common in Noachian-aged terrains but have not been observed in younger terrains (<3.8 Ga). Throughout the Noachian highlands, phyllosilicates are observed in deeply eroded terrains as well as in association with impact craters, in their walls, rims, ejecta, and in central peaks of craters as large as 45 km, corresponding to excavation depths of 4-5 km. CRISM and OMEGA mapping typically show phyllosilicate-bearing rocks occupy the lowest observable stratigraphic unit, and the most common alteration minerals are iron magnesium smectites which typically form at low pressures and temperatures <200°C. Widespread occurrences of phyllosilicates to depths of at least 4-5 km may provide evidence for deep crustal hydrothermal circulation during the Noachian. Geophysical evidence from surface deformation associated with faulting and from the analysis of the relationship of gravity and topography suggest elastic lithosphere thicknesses a large as ~30 km near the end of the Noachian, corresponding to surface heatflux of 20-40 mW/m2. Relaxation of elastic stresses due to thermally activated creep results in elastic lithosphere thicknesses sensitive to crustal temperatures. Plausible planetary thermal evolution models with chondritic abundances of heat producing elements predict a surface heat flux of 50-60 mW/m2 near the end of the Noachian. The difference in the heat flux required for planetary cooling and that inferred from elastic lithospheric thickness, suggests that a significant fraction of heatflow reaching the surface may be transported by hydrothermal convection rather than by conduction alone. Relaxation of crustal thickness variations due to lower crustal flow is sensitive to both the temperature and geothermal gradient at the crust-mantle boundary. In the presence

  2. The effect of mineral composition on the sorption of cesium ions on geological formations.

    PubMed

    Kónya, József; Nagy, Noémi M; Nemes, Zoltán

    2005-10-15

    The sorption of cesium-137 on rock samples, mainly on clay rocks, is determined as a function of the mineral composition of the rocks. A relation between the mineral groups (tectosilicates, phyllosilicates, clay minerals, carbonates) and their cesium sorption properties is shown. A linear model is constructed by which the distribution coefficients of the different minerals can be calculated from the mineral composition and the net distribution coefficient of the rock. On the basis of the distribution coefficients of the minerals the cesium sorption properties of other rocks can be predicted.

  3. Compositional studies of primitive asteroids

    NASA Technical Reports Server (NTRS)

    Vilas, Faith

    1991-01-01

    The aqueous alteration history in the solar system are studied through acquiring additional CCD reflectance spectra in the blue-UV through near-IR spectral region and analyzing these spectra for information about iron oxides in phyllosilicates identified in the CM and CI carbonaceous chondrites. Emphasis is on the main-belt and Cybele primitive asteroids, as these asteroids show spectral diversity and are also spectral analogues for known meteorite samples. The porphyrin bands found in organics near 0.4 micron is also sought.

  4. Gram-negative Biomass in Clay Minerals Analogs: Testing Habitability Potential for the 2011 Mars Science Laboratory Mission

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; McKay, C. P.

    2009-12-01

    Landing sites of next missions to Mars i.e., the US 2011 Mars Science Laboratory (MSL11) and the ESA2016 Pasteur ExoMars, will include phyllosilicate outcrops as targets for investigating the geological and biological history of that planet. In this context, we present a study assessing the living biomass and habitability potential in mineralogical Mars analogs such as phyllosilicates and hematite-rich deposits encompassing a broad arid-hyper-arid climate range (annual rainfall <0.2 to ~700mm/y). Samples from the Atacama Desert (Chile), the Death Valley (CA), and the California Coast (USA) were analyzed for microbial lipopolysaccharide (LPS) as proxy for Gram-negatives biomass with the Limulus-Amebocite-Lysate (LAL) assay. Mineral phases were identified using X-Ray-Diffraction (XRD). These samples resulted to contain phyllosilicate phases similar to those identified, or inferred [1], on the surface of Mars by the OMEGA-Mars/Express [e.g., 2], the Mars Reconnaissance Orbiter (MRO) instruments (HiRISE and CRISM) [3]. Basic observations were: 1) there is no systematic pattern in biomass content of clays vs. non-clays (oxidized) materials from the study sites; 2) Atacama desiccation polygons (muscovite and kaolinite) and contiguous hematite-rich hyper-arid deposits contain the lowest biomass, i.e., ~104to-105 cells/g, respectively; 3) the hyper-arid clays contain three-order magnitude lower Gram-negative biomass than those (montmorillonite, illite, and chlorite) from the arid Death Valley site (~107cells/g); and 4) finally, the Gram-negative (~107cells/g) of clay minerals-rich materials from the arid site is about the same than that (~1.5 to ~3.0 x 107cells/g) of water-saturated massive deposits (kaolinite, illite, and vermiculite) from the wetter California coast. Results from this investigation will help testing for the habitability potential of phyllosilicate deposits sampled by the MSL11 Mission. REFERENCES:[1] Bibring et al., 2006, Science 312:400-404; [2] Wang et

  5. SciT

    Chaiko, David J.; Leyva, Argentina A.

    The invention provides methods for making clay/wax nanocomposites and coatings and films of same with improved chemical resistance and gas barrier properties. The invention further provides methods for making and using emulsions of such clay/wax nanocomposites. Typically, an organophillic clay is combined with a wax or wax/polymer blend such that the cohesion energy of the clay matches that of the wax or wax/polymer blend. Suitable organophilic clays include mica and phyllosilicates that have been surface-treated with edge or edge and surface modifying agents. The resulting nanocomposites have applications as industrial coatings and in protective packaging.

  6. Hints of Habitable Environments on Mars Challenge Our Studies of Mars-Analog Sites on Earth

    NASA Technical Reports Server (NTRS)

    desMarais, David J

    2009-01-01

    Life as we know it requires water with a chemical activity (alpha) >or approx.0.6 and sources of nutrients and useful energy. Some biota can survive even if favorable conditions occur only intermittently, but the minimum required frequency of occurrences is poorly understood. Recent discoveries have vindicated the Mars exploration strategy to follow the water. Mars Global Surveyor s Thermal Emission Spectrometer (TES) found coarse-grained hematite at Meridiani Planum. Opportunity rover confirmed this and also found evidence of ancient sulfate-rich playa lakes and near-surface groundwater. Elsewhere, TES found evidence of evaporitic halides in topographic depressions. But alpha might not have approached 0.6 in these evaporitic sulfate- and halide-bearing waters. Mars Express (MEX) and Mars Reconnaissance Orbiter (MRO) found extensive sulfate evaporites in Meridiani and Valles Marineris. MEX found phyllosilicates at several sites, most notably Mawrth Valles and Nili Fossae. MRO's CRISM near-IR mapper extended the known diversity and geographic distribution of phyllosilicates to include numerous Noachian craters. Phyllosilicates typically occur at the base of exposed ancient rock sections or in sediments in early Hesperian craters. It is uncertain whether the phyllosilicates developed in surface or subsurface aqueous environments and how long aqueous conditions persisted. Spirit rover found remarkably pure ferric sulfate, indicating oxidation and transport of Fe and S, perhaps in fumaroles or hot springs. Spirit also found opaline silica, consistent with hydrothermal activity. CRISM mapped extensive silica deposits in the Valles Marineris region, consistent with aqueous weathering and deposition. CRISM also found ultramafic rocks and magnesite at Nili Fossae, consistent with serpentinization, a process that can sustain habitable environments on Earth. The report of atmospheric methane implies subsurface aqueous conditions. A working hypothesis is that aqueous

  7. Modeling of Sulfide Microenvironments on Mars

    NASA Technical Reports Server (NTRS)

    Schwenzer, S. P.; Bridges, J. C.; McAdam, A.; Steer, E. D.; Conrad, P. G.; Kelley, S. P.; Wiens, R. C.; Mangold, N.; Grotzinger, J.; Eigenbrode, J. L.; hide

    2016-01-01

    Yellowknife Bay (YKB; sol 124-198) is the second site that the Mars Science Laboratory Rover Curiosity investigated in detail on its mission in Gale Crater. YKB represents lake bed sediments from an overall neutral pH, low salinity environment, with a mineralogical composition which includes Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral phyllosilicates. We investigate whether sulfide alteration could be associated with ancient habitable microenvironments in the Gale mudstones. Some textural evidence for such alteration may be pre-sent in the nodules present in the mudstone.

  8. The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis

    NASA Astrophysics Data System (ADS)

    Panfili, Frédéric; Manceau, Alain; Sarret, Géraldine; Spadini, Lorenzo; Kirpichtchikova, Tatiana; Bert, Valérie; Laboudigue, Agnès; Marcus, Matthew A.; Ahamdach, Noureddine; Libert, Marie-Françoise

    2005-05-01

    The maintenance of waterways generates large amounts of dredged sediments, which are deposited on adjacent land surfaces. These sediments are often rich in metal contaminants and present a risk to the local environment. Understanding how the metals are immobilized at the molecular level is critical for formulating effective metal containment strategies such as phytoremediation. In the present work, the mineralogical transformations of Zn-containing phases induced by two graminaceous plants (A grostis tenuis and Festuca rubra) in a contaminated sediment ([Zn] = 4700 mg kg -1, [P 2O 5] = 7000 mg kg -1, pH = 7.8), untreated or amended with hydroxylapatite (AP) or Thomas basic slag (TS), were investigated after two yr of pot experiment by scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS), synchrotron-based X-ray microfluorescence (μ-SXRF), and powder and laterally resolved extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. The number and nature of Zn species were evaluated by principal component (PCA) and least-squares fitting (LSF) analysis of the entire set of μ-EXAFS spectra, which included up to 32 individual spectra from regions of interest varying in chemical composition. Seven Zn species were identified at the micrometer scale: sphalerite, gahnite, franklinite, Zn-containing ferrihydrite and phosphate, (Zn-Al)-hydrotalcite, and Zn-substituted kerolite-like trioctahedral phyllosilicate. Bulk fractions of each species were quantified by LSF of the powder EXAFS spectra to linear combinations of the identified Zn species spectra. In the untreated and unvegetated sediment, Zn was distributed as ˜50% (mole ratio of total Zn) sphalerite, ˜40% Zn-ferrihydrite, and ˜10 to 20% (Zn-Al)-hydrotalcite plus Zn-phyllosilicate. In unvegetated but amended sediments (AP and TS), ZnS and Zn-ferrihydrite each decreased by 10 to 20% and were replaced by Zn-phosphate (˜30˜40%). In the presence of plants, ZnS was almost completely

  9. Importance of clay size minerals for Fe(III) respiration in a petroleum-contaminated aquifer

    Shelobolina, Evgenya S.; Anderson, Robert T.; Vodyanitskii, Yury N.; Sivtsov, Anatolii V.; Yuretich, Richard; Lovely, Derek R.

    2004-01-01

    The availability of Fe(III)-bearing minerals for dissimilatory Fe(III) reduction was evaluated in sediments from a petroleum-contaminated sandy aquifer near Bemidji, Minnesota (USA). First, the sediments from a contaminated area of the aquifer, in which Fe(III) reduction was the predominant terminal electron accepting process, were compared with sediments from a nearby, uncontaminated site. Data from 0.5 m HCl extraction of different size fractions of the sediments revealed that the clay size fraction contributed a significant portion of the ‘bio-available’ Fe(III) in the background sediment and was the most depleted in ‘bio-available’ Fe(III) in the iron-reducing sediment. Analytical transmission electron microscopy (TEM) revealed the disappearance of thermodynamically unstable Fe(III) and Mn(IV) hydroxides (ferrihydrite and Fe vernadite), as well as a decrease in the abundance of goethite and lepidocrocite in the clay size fraction from the contaminated sediment. TEM observations and X-ray diffraction examination did not provide strong evidence of Fe(III)-reduction-related changes within another potential source of ‘bio-available’ Fe(III) in the clay size fraction – ferruginous phyllosilicates. However, further testing in the laboratory with sediments from the methanogenic portion of the aquifer that were depleted in microbially reducible Fe(III) revealed the potential for microbial reduction of Fe(III) associated with phyllosilicates. Addition of a clay size fraction from the uncontaminated sediment, as well as Fe(III)-coated kaolin and ferruginous nontronite SWa-1, as sources of poorly crystalline Fe(III) hydroxides and structural iron of phyllosilicates respectively, lowered steady-state hydrogen concentrations consistent with a stimulation of Fe(III) reduction in laboratory incubations of methanogenic sediments. There was no change in hydrogen concentration when non-ferruginous clays or no minerals were added. This demonstrated that Fe

  10. Long-term product consistency test of simulated 90-19/Nd HLW glass

    NASA Astrophysics Data System (ADS)

    Gan, X. Y.; Zhang, Z. T.; Yuan, W. Y.; Wang, L.; Bai, Y.; Ma, H.

    2011-01-01

    Chemical durability of 90-19/Nd glass, a simulated high-level waste (HLW) glass in contact with the groundwater was investigated with a long-term product consistency test (PCT). Generally, it is difficult to observe the long term property of HLW glass due to the slow corrosion rate in a mild condition. In order to overcome this problem, increased contacting surface ( S/ V = 6000 m -1) and elevated temperature (150 °C) were employed to accelerate the glass corrosion evolution. The micro-morphological characteristics of the glass surface and the secondary minerals formed after the glass alteration were analyzed by SEM-EDS and XRD, and concentrations of elements in the leaching solution were determined by ICP-AES. In our experiments, two types of minerals, which have great impact on glass dissolution, were found to form on 90-19/Nd HLW glass surface when it was subjected to a long-term leaching in the groundwater. One is Mg-Fe-rich phyllosilicates with honeycomb structure; the other is aluminosilicates (zeolites). Mg and Fe in the leaching solution participated in the formation of phyllosilicates. The main components of phyllosilicates in alteration products of 90-19/Nd HLW glass are nontronite (Na 0.3Fe 2Si 4O 10(OH) 2·4H 2O) and montmorillonite (Ca 0.2(Al,Mg) 2Si 4O 10(OH) 2·4H 2O), and those of aluminosilicates are mordenite ((Na 2,K 2,Ca)Al 2Si 10O 24·7H 2O)) and clinoptilolite ((Na,K,Ca) 5Al 6Si 30O 72·18H 2O). Minerals like Ca(Mg)SO 4 and CaCO 3 with low solubility limits are prone to form precipitant on the glass surface. Appearance of the phyllosilicates and aluminosilicates result in the dissolution rate of 90-19/Nd HLW glass resumed, which is increased by several times over the stable rate. As further dissolution of the glass, both B and Na in the glass were found to leach out in borax form.

  11. Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data

    NASA Astrophysics Data System (ADS)

    Bibring, Jean-Pierre; Langevin, Yves; Mustard, John F.; Poulet, François; Arvidson, Raymond; Gendrin, Aline; Gondet, Brigitte; Mangold, Nicolas; Pinet, P.; Forget, F.; OMEGA Team; Berthé, Michel; Gomez, Cécile; Jouglet, Denis; Soufflot, Alain; Vincendon, Mathieu; Combes, Michel; Drossart, Pierre; Encrenaz, Thérèse; Fouchet, Thierry; Merchiorri, Riccardo; Belluci, GianCarlo; Altieri, Francesca; Formisano, Vittorio; Capaccioni, Fabricio; Cerroni, Pricilla; Coradini, Angioletta; Fonti, Sergio; Korablev, Oleg; Kottsov, Volodia; Ignatiev, Nikolai; Moroz, Vassilli; Titov, Dimitri; Zasova, Ludmilla; Loiseau, Damien; Pinet, Patrick; Doute, Sylvain; Schmitt, Bernard; Sotin, Christophe; Hauber, Ernst; Hoffmann, Harald; Jaumann, Ralf; Keller, Uwe; Arvidson, Ray; Duxbury, Tom; Neukum, G.

    2006-04-01

    Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the ``phyllocian'' era) are found in the oldest terrains; sulfates were formed in a second era (the ``theiikian'' era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the ``siderikian'') is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.

  12. Aqueous alteration in the Kaba CV3 carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Buseck, Peter R.

    1990-01-01

    Results from TEM and SEM examinations of the Kaba CV3 carbonaceous chondrite are presented, showing that the chondrules and the matrix of Kaba have undergone pervasive low-temperature aqueous alteration, resulting in the formation of Fe-bearing saponite from glass and enstatite in chondrules, and from anhydrous silicates in matrix. The alteration products in Kaba were found to resemble those in other aqueously altered carbonaceous chondrites such as the Mokoia CV3 and in Orgueil CI chondrites and Y-82162 chondrites. However, Kaba lacks the abundant high-Al phyllosilicates, reported for CAIs from Mokoia, and the serpentine and ferrihydrite, found in Orgueil.

  13. Visible and Near-IR Reflectance Spectra of Mars Analogue Materials Under Arid Conditions for Interpretation of Martian Surface Mineralogy

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Graff, T. G.; Achilles, C. N.; Agresti, D. G.; Ming, D. W.; Golden, D. C.

    2011-01-01

    Visible and near-IR (VNIR) spectra from the hyper-spectral imagers MRO-CRISM and Mars Express OMEGA in martian orbit have signatures from Fe-bearing phases (e.g., olivine, pyroxene, and jarosite), H2O/OH-bearing phases (e.g., smectites and other phyllosilicates, sulfates, and high-SiO2 phases), and carbonate [e.g., 1-5]. Mineralogical assignments of martian spectral features are made on the basis of VNIR spectra acquired in the laboratory under appropriate environmental conditions on samples whose mineralogical composition is known. We report here additional results for our ongoing project [6] to acquire VNIR spectra under arid conditions.

  14. Authigenesis/Diagenesis of the Murray Formation Mudstone in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Ming, D. W.; Rampe, E. B.; Grotzinger, J. P.; Hurowitz, J. A.; Morris, R. V.; Yen, A. S.; Blake, D. B.; Geller, R.; Sutter, B.

    2016-01-01

    The Mars Science Laboratory rover Curiosity has been exploring sedimentary deposits in Gale crater since August, 2012. The rover has traversed up section through approximately 150 m of sedimentary rocks deposited in fluvial, deltaic, and lacustrine environments (Bradbury group and overlying Mount Sharp group). The Murray formation lies at the base of the Mt. Sharp group and has been interpreted to be a finely laminated mudstone likely deposited in a subaqueous lacustrine environment. Four drill samples from several elevations in the Murray fm have been acquired by the rover's sampling system and delivered to the CheMin XRD instrument. The lower section of the Murray fm contains 2:1 phyllosilicate(s), hematite, jarosite, XRD amorphous materials, and primary basaltic minerals. Further up section, the Murray fm contains magnetite, cristobalite, tridymite, abundant Si-rich XRD amorphous materials along with plagioclase and K-feldspars. Murray formation materials appear to have been altered under an open hydrologic system based on the bulk chemistry of these materials measured by the Alpha Particle X-ray Spectrometer (APXS). The 2:1 phyllosilicate only occurs in the lowermost section of the Murray fm and may be detrital or formed during authigenesis of Murray fm materials, similar to the Fe-saponite and magnetite detected in a mudstone in the Yellowknife Bay fm near Curiosity's landing site (stratigraphically at the base of the Bradbury group). The occurrence of jarosite and hematite in the lower section indicates an acidic diagenetic event. These phases may have formed via several acidic alteration mechanisms, including (1) oxidative weathering of mafic igneous rocks containing sulfides; (2) sulfuric acid weathering of Fe-bearing phases; and (3) near-neutral pH subsurface solutions rich in Fe2(+) that were rapidly oxidized to Fe3(+), which produced excess acidity. The transition from abundant hematite in the lowermost Murray fm to magnetite moving up section may

  15. Magnetic anisotropy of Silurian organic-rich shale rocks and calcareous concretions from Northern Poland

    NASA Astrophysics Data System (ADS)

    Niezabitowska, Dominika; Szaniawski, Rafał

    2017-04-01

    The research has been performed on Wenlockian shales of Pelplin formation from the Pomerania region located in Northern Poland. These organic-rich marine shales were deposited on the western shelf of the Baltica paleo-continent and currently they constitute the cover of East European Platform. The studied shales lie almost completely flat without signs of tectonic deformations. Rock magnetic studies were carried out with the aim of recognizing ferro- and paramagnetic minerals in shales and thus fully understanding the origin of the magnetic anisotropy. The typical dark shales and spherical calcareous concretions from two boreholes were sampled. Based on deflection of shales beds bordered with a concretions, we deduce that such concretions were formed in the early stage of diagenesis, before the final compaction and lithification of surrounding shales. We obtained similar rockmagnetic results for both of rock types. The results of thermal variation of magnetic susceptibility and hysteresis loops show that the magnetic susceptibility is mainly controlled by paramagnetic minerals, due to domination of phyllosilicate minerals, with a smaller impact of ferromagnetic phase. The results of the hysteresis studies documented the domination of low coercivity ferromagnetic minerals, that is magnetite and pyrrhotite. The deposition alignment of flocculated phyllosilicates and further compaction determine distinct bedding parallel foliation of the AMS (Anisotropy of Magnetic Susceptibility) in the both drill cores. In one of the drill core the maximal AMS axes are almost randomly distributed in the bedding plane and show only a weak tendency for grouping. In the second drill core the magnetic lineation is better defined. In the case of concretions the bedding parallel magnetic foliation is also evident but it is much weaker than in shales. In turn, the magnetic lineation in the both drill cores is well developed and the maximal AMS axes are well grouped. In both of the cores

  16. Erosion of Edge of the South Polar Layered Deposits

    2017-05-23

    This image from NASA's Mars Reconnaissance Orbiter shows small ripples, about 10 meters apart, located in Her Desher Vallis. Her Desher is a small channel that shows evidence of phyllosilicates -- silicates with a sheet-like structure, such as clay minerals. Much larger images of this area show that Her Desher Vallis appears isolated, with no obvious connections to craters or larger valleys. Her Desher, the ancient Egyptian name for Mars, translates to "the Red One." https://photojournal.jpl.nasa.gov/catalog/PIA21639

  17. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    NASA Astrophysics Data System (ADS)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  18. Comparison of the Composition of the Tempel 1 Ejecta to the Dust in Comet C/Hale-Bopp 1995 O1 and YSO HD 100546

    DTIC Science & Technology

    2007-01-01

    niningerits.Blue phyllosililcates (near the sulfldes), represented here by the smectite nontronite. (b) Spectrum after subtraction of the best-fit silicate...1.70 Smectite nontrmite 0.14 2.3 496 0.07 340 3.76 Nasn3Fe2(Si.AjMO 0j(OH)2-3H20 Carbonats Mageuile (MgC0 3 ) 0.030 3.1 84 0.11 340 1.30 Siderite...any other comet, was optically thick near the nucleus due to its Phyllosilicates (as represented by the smectite nontron- huge rate of emission of

  19. How the Assumed Size Distribution of Dust Minerals Affects the Predicted Ice Forming Nuclei

    NASA Technical Reports Server (NTRS)

    Perlwitz, Jan P.; Fridlind, Ann M.; Garcia-Pando, Carlos Perez; Miller, Ron L.; Knopf, Daniel A.

    2015-01-01

    The formation of ice in clouds depends on the availability of ice forming nuclei (IFN). Dust aerosol particles are considered the most important source of IFN at a global scale. Recent laboratory studies have demonstrated that the mineral feldspar provides the most efficient dust IFN for immersion freezing and together with kaolinite for deposition ice nucleation, and that the phyllosilicates illite and montmorillonite (a member of the smectite group) are of secondary importance.A few studies have applied global models that simulate mineral specific dust to predict the number and geographical distribution of IFN. These studies have been based on the simple assumption that the mineral composition of soil as provided in data sets from the literature translates directly into the mineral composition of the dust aerosols. However, these tables are based on measurements of wet-sieved soil where dust aggregates are destroyed to a large degree. In consequence, the size distribution of dust is shifted to smaller sizes, and phyllosilicates like illite, kaolinite, and smectite are only found in the size range 2 m. In contrast, in measurements of the mineral composition of dust aerosols, the largest mass fraction of these phyllosilicates is found in the size range 2 m as part of dust aggregates. Conversely, the mass fraction of feldspar is smaller in this size range, varying with the geographical location. This may have a significant effect on the predicted IFN number and its geographical distribution.An improved mineral specific dust aerosol module has been recently implemented in the NASA GISS Earth System ModelE2. The dust module takes into consideration the disaggregated state of wet-sieved soil, on which the tables of soil mineral fractions are based. To simulate the atmospheric cycle of the minerals, the mass size distribution of each mineral in aggregates that are emitted from undispersed parent soil is reconstructed. In the current study, we test the null

  20. The Nature of C Asteroid Regolith Revealed from the Jbilet Winselwan CM Chondrite

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.

    2016-01-01

    C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be asteroid 162173 Ryugu, the target of the Hayabusa 2 mission, although most spectra of Ryugu are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C-class asteroids - impact shock melting. Impact shock melting has been proposed to ex-plain some mineralogical characteristics of CB chondrites, but has rarely been considered a major process for hydrous carbonaceous chondrites.

  1. Clay minerals in primitive meteorites and interplanetary dust 2. Smectites and micas

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Zolensky, M. E.

    1991-01-01

    The classification is briefly summarized of stony meteorites and cosmic dust, and the mineralogy and chemistry is described of serpentine group minerals. The occurrence of smectites and micas in extraterrestrial materials is examined. The characterization of fine grained minerals in meteorites and IDPs relies heavily on electron beam instruments, especially the transmission electron microscope (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites lose their interlayer water and the interlayer partly collapse in the high vacuum of the TEM.

  2. Microscale Relationships Between Fault Rock Fabric and Structural Style in Megathrusts - Observations from Tohoku-Oki Via J-Fast.

    NASA Astrophysics Data System (ADS)

    Toy, V. G.; Fagereng, A.; Kirkpatrick, J. D.; Remitti, F.; Rowe, C. D.; Ujiie, K.; Wolfson-Schwehr, M.

    2014-12-01

    Recovered plate boundary thrust material from the site of the 2011 Tohoku-Oki earthquake rupture contains both distributed and localized fabrics. We1 infer these reflect two end members of behavior, namely steady state creep of weak, velocity/strain-hardening materials versus episodic, seismic failure of strong, velocity/strain-weakening materials. Core and downhole observations and mechanical tests demonstrate the fault rock is primarily smectite and has very low frictional strength (μk~0.08) 2,3,4,5. Additional observations of the recovered core indicate microscale fabrics affect mechanical properties. The fault zone fabric is defined mostly by anastomosing dark surfaces surrounding phacoids. Phacoid size and intensity of dark surfaces vary, probably reflecting differences in total strain. Phacoids contain foliations at angles to their long axes and bounding surfaces. Remnant bedding can be recognized in places, based on variation in phyllosilicate colour or clastic:phyllosilicate ratio (although other colour variations result from alteration1). Anastomosing shear surfaces may coincide with bedding but also commonly truncate it, indicating little primary lithological/rheological control on fabric formation. However, in late mm-thickness, through going, more intensely sheared zones, lithologic contrast more strongly defines phacoids while dark seams may be absent. A transition from distributed shear in phyllosilicates to localized shear on dark surfaces requires local change in stress or strain rate. If the orientation of clay fabrics change due to folding ('turbulent' flow), then weak basal planes of phyllosilicates rotated into unfavourable orientations may act as 'stress risers' promoting localization around phacoids containing poorly oriented fabrics. This mechanism is indicated by the presence of the most folded layering in plate boundary core adjacent to the most distinct through-going surfaces1,2. Alternatively, locally well-oriented fabrics may

  3. Low-cost zinc-plated photoanode for fabric-type dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kong, Lingfeng; Bao, Yunna; Guo, Wanwan; Cheng, Li; Du, Jun; Liu, Renlong; Wang, Yundong; Fan, Xing; Tao, Changyuan

    2016-02-01

    Fabric-type flexible solar cells have been recently proposed as a very promising power source for wearable electronics. To increase the photocurrent of fabric-type flexible solar cells, low-cost zinc-plated wire and mesh photoanodes are assembled for the first time through a mild wet process. Given the protection of the compact protection layer, the DSSC device could benefit from the low work function of Zn and self-repairing behavior on the Zn/ZnO interface. An evident current increase by ∼6 mA/cm2 could be observed after coating a layer of metal Zn on various metal substrates, such as traditional stainless steel wire. Given the self-repairing behavior on Zn/ZnO interface, the Zn layer can help to improve the interfacial carrier transfer, leading to better photovoltaic performance, for both liquid-type and solid-type cells.

  4. Controlling interface oxygen for forming Ag ohmic contact to semi-polar (1 1 -2 2) plane p-type GaN

    NASA Astrophysics Data System (ADS)

    Park, Jae-Seong; Han, Jaecheon; Seong, Tae-Yeon

    2014-11-01

    Low-resistance Ag ohmic contacts to semi-polar (1 1 -2 2) p-GaN were developed by controlling interfacial oxide using a Zn layer. The 300 °C-annealed Zn/Ag samples showed ohmic behavior with a contact resistivity of 6.0 × 10-4 Ω cm2 better than that of Ag-only contacts (1.0 × 10-3 Ω cm2). The X-ray photoemission spectroscopy (XPS) results showed that annealing caused the indiffusion of oxygen at the contact/GaN interface, resulting in the formation of different types of interfacial oxides, viz. Ga-oxide and Ga-doped ZnO. Based on the XPS and electrical results, the possible mechanisms underlying the improved electrical properties of the Zn/Ag samples are discussed.

  5. The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor.

    PubMed

    Minnoş, Bihter; Ilhan-Sungur, Esra; Çotuk, Ayşın; Güngör, Nihal Doğruöz; Cansever, Nurhan

    2013-01-01

    The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor was investigated over a 10-month period in a hotel. Planktonic and sessile numbers of sulphate reducing bacteria (SRB) and heterotrophic bacteria were monitored. The corrosion rate was determined by the weight loss method. The corrosion products were analyzed by energy dispersive X-ray spectroscopy and X-ray diffraction. A mineralized, heterogeneous biofilm was observed on the coupons. Although a biocide and a corrosion inhibitor were regularly added to the cooling water, the results showed that microorganisms, such as SRB in the mixed species biofilm, caused corrosion of galvanized steel. It was observed that Zn layers on the test coupons were completely depleted after 3 months. The Fe concentrations in the biofilm showed significant correlations with the weight loss and carbohydrate concentration (respectively, p < 0.01 and p < 0.01).

  6. Electrodeposition of nanostructured Sn-Zn coatings

    NASA Astrophysics Data System (ADS)

    Salhi, Y.; Cherrouf, S.; Cherkaoui, M.; Abdelouahdi, K.

    2016-03-01

    The electrodeposition of Sn-Zn coating at ambient temperature was investigated. The bath consists of metal salts SnCl2·2H2O and ZnSO4·7H2O and sodium citrate (NaC6H5Na3O7·2H2O) as complexing agent. To prevent precipitation, the pH is fixed at 5. Reducing tin and zinc through Sncit2- and ZnHcit- complex respectively is confirmed by the presence of two cathodic peaks on the voltammogram. The kinetic of tin (II) reduction process is limited by the SnCit2- dissociation. The SEM and TEM observations have showed that the coating consists of a uniform Sn-Zn layer composed of fine grains on which tin aggregates grow up. XRD revealed peaks corresponding to the hexagonal Zn phase and the tetragonal β-Sn phase.

  7. Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Boulton, Carolyn; Menzies, Catriona D.; Toy, Virginia G.; Townend, John; Sutherland, Rupert

    2017-01-01

    Oblique dextral motion on the central Alpine Fault in the last circa 5 Ma has exhumed garnet-oligoclase facies mylonitic fault rocks from ˜35 km depth. During exhumation, deformation, accompanied by fluid infiltration, has generated complex lithological variations in fault-related rocks retrieved during Deep Fault Drilling Project (DFDP-1) drilling at Gaunt Creek, South Island, New Zealand. Lithological, geochemical, and mineralogical results reveal that the fault comprises a core of highly comminuted cataclasites and fault gouges bounded by a damage zone containing cataclasites, protocataclasites, and fractured mylonites. The fault core-alteration zone extends ˜20-30 m from the principal slip zone (PSZ) and is characterized by alteration of primary phases to phyllosilicate minerals. Alteration associated with distinct mineral phases occurred proximal the brittle-to-plastic transition (T ≤ 300-400°C, 6-10 km depth) and at shallow depths (T = 20-150°C, 0-3 km depth). Within the fault core-alteration zone, fractures have been sealed by precipitation of calcite and phyllosilicates. This sealing has decreased fault normal permeability and increased rock mass competency, potentially promoting interseismic strain buildup.

  8. Slip localization on the southern Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Barth, N. C.; Boulton, C.; Carpenter, B. M.; Batt, G. E.; Toy, V. G.

    2013-06-01

    of a detailed field study of the southern onshore portion of New Zealand's Alpine Fault reveal that for 75 km along-strike, dextral-normal slip on this long-lived structure is highly localized in phyllosilicate-rich fault core gouges and along their contact with more competent rocks. At three localities (Martyr River, McKenzie Creek, and Hokuri Creek), we document complete cross sections through the fault. New 40Ar/39Ar dates on mylonites, combined with microstructural and mechanical data on phyllosilicate-rich fault core gouges show that modern slip is localized onto a single, steeply dipping 1 to 12 m-thick fault core composed of impermeable (k = 10-20 to 10-22 m2), frictionally weak (μs = 0.12-0.37), velocity-strengthening, illite-chlorite, and saponite-chlorite-lizardite fault gouges. Fault core materials are (1) comparable to those of other major weak-cored faults (e.g., San Andreas Fault) and (2) most compatible with fault creep, despite paleoseismic evidence of quasiperiodic large magnitude earthquakes (Mw > 7) on this portion of the Alpine Fault. We conclude that frictional properties of gouges at the surface do not characterize the overall seismogenic behavior of the southern Alpine Fault.

  9. Mineralogy and petrography of C asteroid regolith: The Sutter's Mill CM meteorite

    NASA Astrophysics Data System (ADS)

    Zolensky, Michael; Mikouchi, Takashi; Fries, Marc; Bodnar, Robert; Jenniskens, Peter; Yin, Qing-zhu; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Colbert, Matthew; Hanna, Romy; Maisano, Jessie; Ketcham, Richard; Kebukawa, Yoko; Nakamura, Tomoki; Matsuoka, Moe; Sasaki, Sho; Tsuchiyama, Akira; Gounelle, Matthieu; Le, Loan; Martinez, James; Ross, Kent; Rahman, Zia

    2014-11-01

    Based upon our characterization of three separate stones by electron and X-ray beam analyses, computed X-ray microtomography, Raman microspectrometry, and visible-IR spectrometry, Sutter's Mill is a unique regolith breccia consisting mainly of various CM lithologies. Most samples resemble existing available CM2 chondrites, consisting of chondrules and calcium-aluminum-rich inclusion (CAI) set within phyllosilicate-dominated matrix (mainly serpentine), pyrrhotite, pentlandite, tochilinite, and variable amounts of Ca-Mg-Fe carbonates. Some lithologies have witnessed sufficient thermal metamorphism to transform phyllosilicates into fine-grained olivine, tochilinite into troilite, and destroy carbonates. One finely comminuted lithology contains xenolithic materials (enstatite, Fe-Cr phosphides) suggesting impact of a reduced asteroid (E or M class) onto the main Sutter's Mill parent asteroid, which was probably a C class asteroid. One can use Sutter's Mill to help predict what will be found on the surfaces of C class asteroids such as Ceres and the target asteroids of the OSIRIS-REx and Hayabusa 2 sample return missions (which will visit predominantly primitive asteroids). C class asteroid regolith may well contain a mixture of hydrated and thermally dehydrated indigenous materials as well as a significant admixture of exogenous material would be essential to the successful interpretation of mineralogical and bulk compositional data.

  10. Abiotic protein fragmentation by manganese oxide: Implications for a mechanism to supply soil biota with oligopeptides

    DOE PAGES

    Reardon, Patrick N.; Chacon, Stephany S.; Walter, Eric D.; ...

    2016-03-14

    Proteins facilitate a wide range of chemical transformations important in soil as well as being a major reservoir of soil nitrogen themselves. The interactions and reactions of proteins with soils and minerals are of key importance to our understanding of their functional persistence in the environment. We combined NMR and EPR spectroscopies to distinguish the reaction of a model protein with a redox active mineral surface (Birnessite, MnO 2) from its response to a redox neutral phyllosilicate (Kaolinite). Our data demonstrate that birnessite fragments the model protein while kaolinite has little impact on the protein structure. NMR and EPR spectroscopiesmore » are shown to be valuable tools to observe these reactions and capture the extent of protein transformation together with the extent of mineral response. These data suggest that mineral surfaces can have both promoting and retarding roles in terrestrial nitrogen cycling, with redox active minerals acting as accelerators by catalyzing the breakdown of proteins and proteinaceous materials while phyllosilicates are more likely to act as preservative media.« less

  11. FIB-TEM Investigations of Fe-NI-Sulfides in the CI Chondrites Alais and Orgueil

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Lauretta, D. S.; Zega, T. J.; Keller, L. P.

    2013-01-01

    The CI chondrites are primitive meteorites with bulk compositions matching the solar photosphere for all but the lightest elements. They have been extensively aqueously altered, and are composed primarily of fine-grained phyllosilicate matrix material which is host to carbonates, sulfates, sulfides, and minor amounts of olivine and pyroxene. The alteration, while extensive, is heterogeneous. For example, CI-chondrite cubanite and carbonate grains differ on mm to sub-mm scales, demonstrating multiple aqueous episodes. CI-chondrite variability is also evidenced by degree of brecciation, abundance and size of coarse-grained phyllosilicates, olivine and pyroxene abundance, as well as Ni-content and size of sulfide grains. Our previous work revealed Orgueil sulfide grains with variable Ni-contents, metal:S ratios, crystal structures and textures. We continue to explore the variability of CI-chondrite pyrrhotite (Po, (FeNi)1-xS) and pentlandite (Pn, (Fe,Ni)9S8) grains. We investigate the microstructure of sulfides within and among CI-chondrite meteorites in order to place constraints on the conditions under which they formed.

  12. Development of magnetic and elastic anisotropies in slates during progressive deformation

    NASA Astrophysics Data System (ADS)

    Hrouda, František; Pros, Zdeněk; Wohlgemuth, Jiří

    1993-05-01

    Magnetic and elastic anisotropies were investigated in rocks of the Nízký Jeseník Mountains (northeast Bohemian Massif) ranging in lithology from almost unmetamorphosed sediments, through slate, to phyllite, and showing a range of structural styles from sedimentary, through spaced and slaty cleavage, to metamorphic schistosity. In unmetamorphosed and undeformed sedimentary rocks, both the anisotropies display close relationships to the sedimentary fabric. During the development of the spaced and slaty cleavage they are gradually re-oriented into the attitudes of the deformational fabrics, and in the rocks with metamorphic schistosity they are fully related to the deformational fabric elements, which can be oriented in a very different way from the original sedimentary structures. The magnetic anisotropy is mostly due to the preferred orientation of phyllosilicates generated during very weak regional metamorphism, and subordinately due to the preferred orientation of magnetite. The elastic anisotropy is probably controlled by the preferred orientation of phyllosilicates and by the existence of oriented systems of microcracks.

  13. Fragmentation as a condition for persistence - exploring a new perspective of mineral-organic interactions

    NASA Astrophysics Data System (ADS)

    Kleber, M.; Liu, S. Y.; Keiluweit, M.; Nico, P. S.; Ahmed, M.

    2012-12-01

    High radiocarbon ages (centennial to millennial) of soil organic matter tend to occur in soils with high proportions of reactive, hydroxylated minerals, including andisols, spodosols and oxisols. This indicates that the most reactive mineral surfaces, i.e. those that should in theory be particularly efficient in promoting transformations of organic matter are among the most powerful in protecting organic matter against decomposition on long time scales. The easiest way to reconcile this apparent paradox is to assume that organic compounds become fragmented upon contact with minerals, thereby generating fragmentation products which in turn are more likely to become preserved within the soil fabric than their precursor molecules. Here we use Vacuum Ultraviolet - Post Ionisation -Mass Spectroscopy (VUV-PI-MS) in combination with thermal and laser desorption to show how organic compounds undergo complete fragmentation upon contact with mineral surfaces. Fragmentation patterns were generally different between oxidic minerals and minerals belonging to the phyllosilicate group. Also, desorption from phyllosilicates generally required significantly higher energies than desorption from oxide phases. Our investigation suggests that, at low energy levels, breakdown and fragmentation is a probably major outcome of mineral-organic interactions. This observation supports a new model for the role of mineral-organic interactions in the preservation of organic compounds in the environment: mineral-induced fragmentation as a prerequisite for long term protection against decomposition.

  14. Detection and context of hydrated mineralogy in the Tyrrhena Terra region, Mars

    NASA Astrophysics Data System (ADS)

    den Haan, J.; Zegers, T. E.; van Ruitenbeek, F. J. A.; van der Werff, H. M. A.; Rossi, A.

    2008-09-01

    Introduction The discovery of phyllosilicates on Mars [1] has had major implications on the perceived geologic and climatologic evolution of Mars [2]. Not only do phyllosilicates represent a `wet' period on Mars, they might also represent a potentially favorable environment for life. The phyllosilicates have so far exclusively been found in or close to ancient Noachian highland terrain. Those phyllosilicate deposits studied (e.g. [3]) show a clear association between hydrated mineralogy and heavily eroded and crater-saturated outcrops. Phyllosilicates on Earth are associated with a wide variety of geological processes (volcanism, metamorphism, hydrothermal alteration, sedimentation). The occurrence of phyllosilicates on Mars may be equally diverse in nature. To be able to place constraints on the early Martian environment, the processes by which these phyllosilicates formed need to be reconstructed. To derive this information from individual phyllosilicate deposits, it is necessary to interpret their composition in relation to their geological context and relative time relationships. We conducted such an integrated hyperspectral and geological study of the Tyrrhena Terra region. Data products ad methods HRSC data products (both image at 12 m/pixel and stereo-derived DTMs) are used for examining geologic cross-cutting relationships, geomorphologic landforms and visual determination of unit boundaries. Odyssey THEMIS nighttime TIR images are analyzed for spatial variations in thermal inertia. Where available, HRSC is supplemented by higher-resolution visible observations of CTX or MOC. Hyperspectral analysis is conducted using data from the OMEGA hyperspectral instrument. In order to batch-process large amounts of OMEGA data, an IDL/ENVI tool was developed on top of the existing SOFT04, distributed by PSA. The applied atmospheric correction assumes that atmospheric contributions are multiplicative, and follow a power-law distribution with altitude [4]. The ratio of

  15. Oxo Crater on (1) Ceres: Geological History and the Role of Water-ice

    SciT

    Nathues, A.; Platz, T.; Hoffmann, M.

    Dwarf planet Ceres (∅ ∼ 940 km) is the largest object in the main asteroid belt. Investigations suggest that Ceres is a thermally evolved, volatile-rich body with potential geological activity, a body that was never completely molten, but one that possibly partially differentiated into a rocky core and an ice-rich mantle, and may contain remnant internal liquid water. Thermal alteration and the infall of exogenic material contribute to producing a (dark) carbonaceous chondritic-like surface containing ammoniated phyllosilicates. Here we report imaging and spectroscopic analyses of data on the bright Oxo crater derived from the Framing Camera and the Visible andmore » Infrared Spectrometer on board the Dawn spacecraft. We confirm that the transitional complex crater Oxo (∅ ∼ 9 km) exhibits exposed surface water-ice. We show that this water-ice-rich material is associated exclusively with two lobate deposits at pole-facing scarps, deposits that also contain carbonates and admixed phyllosilicates. Due to Oxo’s location at −4802 m below the cerean reference ellipsoid and its very young age of only 190 ka (1 σ : +100 ka, −70 ka), Oxo is predestined for ongoing water-ice sublimation.« less

  16. Nanoscale Zirconium-(oxyhydr)oxide in Contaminated Sediments From Hanford, WA - A New Host for Uranium

    NASA Astrophysics Data System (ADS)

    Stubbs, J. E.; Elbert, D. C.; Veblen, L. A.; Zachara, J. M.; Davis, J. A.; Veblen, D. R.

    2008-12-01

    Zirconium-, uranium-, and copper-bearing wastes have leached from former disposal ponds into vadose zone sediments in the 300 Area at the Department of Energy's Hanford Site. Zirconium is enriched in the shallow portion of the vadose zone, and we have discovered an amorphous Zr-(oxyhydr)oxide that contains 16% of the total uranium budget (84.24 ppm) in one of the shallow samples. We have characterized the oxide using electron microprobe analysis (EMPA), a focused ion beam (FIB) instrument, and transmission electron microscopy (TEM). It occurs in fine-grained coatings found on lithic and mineral fragments in these sediments. The oxide is intimately intergrown with the phyllosilicates and other minerals of the coatings, and in places can be seen coating individual, nano-sized phyllosilicate mineral grains. Electron energy-loss spectroscopy (EELS) shows that the Zr-(oxyhydr)oxide has a P:Zr atomic ratio around 0.2, suggesting it is either intergrown with minor amounts of a Zr-phosphate or has adsorbed a significant amount of phosphate. This material has adsorbed or incorporated a substantial amount of uranium. Thus, understanding its nature is critical to predicting the long-term fate of U in the Hanford vadose zone. While the low-temperature uptake of U by Zr-(oxhydr)oxides and phosphates has been studied for several decades in laboratory settings, to our knowledge ours is the first report of such uptake in the field.

  17. Mineral Trends in Early Hesperian Lacustrine Mudstone at Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Ming, D. W.; Grotzinger, J. P.; Morris, R. V.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.; Morrison, S. M.; Yen, A. S.; Chipera, S. J.; hide

    2017-01-01

    The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to study the layered sediments of lower Aeolis Mons (i.e., Mount Sharp), which have signatures of phyllosilicates, hydrated sulfates, and iron oxides in orbital visible/near-infrared observations. The observed mineralogy within the stratigraphy, from phyllosilicates in lower units to sulfates in higher units, suggests an evolution in the environments in which these secondary phases formed. Curiosity is currently investigating the sedimentary structures, geochemistry, and mineralogy of the Murray formation, the lowest exposed unit of Mount Sharp. The Murray formation is dominated by laminated lacustrine mudstone and is approx.200 m thick. Curiosity previously investigated lacustrine mudstone early in the mission at Yellowknife Bay, which represents the lowest studied stratigraphic unit. Here, we present the minerals identified in lacus-trine mudstone from Yellowknife Bay and the Murray formation. We discuss trends in mineralogy within the stratigraphy and the implications for ancient lacustrine environments, diagenesis, and sediment sources.

  18. Visible and Near-IR Reflectance Spectra for Smectite, Sulfate And Perchlorate under Dry Conditions for Interpretation of Martian Surface Mineralogy

    NASA Technical Reports Server (NTRS)

    Morris, R.V.; Ming, W.; Golden, D.C.; Arvidson, R.E.; Wiseman, S.M.; Lichtenberg, K.A.; Cull, S.; Graff, T.G.

    2009-01-01

    Visible and near-IR (VNIR) spectral data for the martian surface obtained from orbit by the MRO-CRISM and OMEGA instruments are interpreted as having spectral signatures of H2O/OH-bearing phases, including smectites and other phyllosilicates, sulfates, and high-SiO2 phases [e.g., 1-4]. Interpretations of martian spectral signatures are based on and constrained by spectra that are obtained in the laboratory on samples with known mineralogical compositions and other physicochemical characteristics under, as appropriate, Mars-like environmental conditions (e.g., temperature, pressure, and humidity). With respect to environmental conditions, differences in the absolute concentration of atmospheric H2O can effect the hydration state and therefore the spectra signatures of smectite phyllosilicates (solvation H2O) and certain sulfates (hydration H2O) [e.g., 5-7]. We report VNIR spectral data acquired under humid (laboratory air) and dry (dry N2 gas) environments for two natural smectites (nontronite API-33A and saponite SapCa-1) to characterize the effect of solvation H2O on spectral properties. We also report spectral data for the thermal dehydration products of (1) melanterite (FeSO4.7H2O) in both air and dry N2 gas and (2) Mg-perchlorate (Mg(ClO4)2.6H2O) in dry N2 environments. Spectral measurements for samples dehydrated in dry N2 were made without exposing them to humid laboratory air.

  19. Mineralogical Indicators for Climate Change on Mars: Evidence from Landed Missions

    NASA Technical Reports Server (NTRS)

    Ming, D. W.; Morris, R. V.; Clark, B. C.

    2015-01-01

    Mineralogical and geochemical data returned by a flotilla of Mars orbiters and landers over the past 10 years has substantially enhanced our understanding on the evolution of the atmosphere and climate. Instruments onboard Mars Express and MRO discovered widespread deposits of phyllosilicates that formed during the Noachian followed by formation of sulfates into the Hesperian. The formation of extensive valley networks along with these layered deposits of phyllosilicates and sulfates during the late Noachian/ early Hesperian indicate a past martian climate that was capable of maintaining liquid water at the surface. The planet's climate changed substantially after these early 'episodes' of water and very little aqueous alteration has occurred over the past 3.5 Gyrs . A key to understanding Mars past climate is to identify, characterize, and age date secondary minerals that have formed by reaction with volatile compounds, e.g., H2O, CO2, SO2. Here, we summarize the detection of secondary minerals at the four landing sites visited over the past 10 years. We also provide potential pathways for their formation and implications for past climate change on Mars.

  20. About Tagish Lake as a Potential Parent Body for Polar Micrometeorites; Clues from their Hydrogen Isotopic Compositions

    NASA Technical Reports Server (NTRS)

    Engrand, C.; Gounelle, M.; Zolensky, M. E.; Duprat, J.

    2003-01-01

    The origin of the Antarctic micrometeorites (AMMs) is still a matter of debate. Their closest meteoritic counterparts are the C2 chondrites, but the match is not perfect, and the parent body(ies) of the AMMs is(are) still to be identified. Tagish Lake is a new meteorite fall which bears similarity with CI1 and CM2 chondrites, but is distinct from both. Based on the mineralogy of phyllosilicates, Noguchi et al. proposed that the phyllosilicate-rich AMMs and the Tagish Lake meteorites could derive from similar asteroids. The hydrogen isotopic compositions of extra-terrestrial samples can be used to get some insight on their origin. The D/H ratios of AMMs and of Tagish Lake have been measured, but using different analytical techniques. They are therefore not directly comparable. We performed additional hydrogen isotopic analyses of fragments of Tagish Lake using the same experimental setup previously used for the measurement of the hydrogen isotopic composition of AMMs. In this work, we could also analyze separately both lithologies of Tagish Lake (carbonate-poor and -rich). The distributions of delta D values measured in the two lithologies of Tagish Lake are very similar, indicating that fluids with similar hydrogen isotopic compositions altered the meteorite on the parent body for the two lithologies. Yet, the hydrogen isotopic composition of Tagish Lake is different from that of AMMs, suggesting that they do not derive from the same parent body.

  1. Zeolites on Mars: Possible environmental indicators in soils and sediments

    NASA Technical Reports Server (NTRS)

    Ming, D. W.; Gooding, J. L.

    1988-01-01

    Weathering products should serve as indicators of weathering environments and may provide the best evidence of the nature of climate change on Mars. No direct mineralogical measurements of Martian regolith were performed by the Viking missions, but the biology and X-ray fluorescence experiments provided some information on the physiochemical properties of Martian regolith. Most post-Viking studies of candidate weathering products have emphasized phyllosilicates and Fe-oxides; zeolites are potentially important, but overlooked, candidate Martian minerals. Zeolites would be important on Mars for three different reasons. First, they are major sinks of atmospheric gases and, per unit mass, are stronger and more efficient sorbents than are phyllosilicates. Secondly, they can be virtually unique sorbents and shelters for organic compounds and possible catalysts for organic-based reactions. Finally, their exchangeable ions are good indicators of the chemical properties of solutions with which they have communicated. Accordingly, the search for information on past compositions of the Martian atmosphere and hydrosphere should find zeolites to be rich repositories.

  2. Determining the relative extent of alteration in CM chondrites

    NASA Technical Reports Server (NTRS)

    Browning, Lauren B.; Mcsween, Harry Y., Jr.; Zolensky, Michael

    1993-01-01

    The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

  3. Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species

    SciT

    Du, Huihui; Qu, ChenChen; Liu, Jing

    Bacteria and phyllosilicate commonly coexist in the natural environment, producing various bacteria–clay complexes that are capable of immobilizing heavy metals, such as cadmium, via adsorption. However, the molecular binding mechanisms of heavy metals on these complex aggregates still remain poorly understood. This study investigated Cd adsorption on Gram-positive B. subtilis, Gram-negative P. putida and their binary mixtures with montmorillonite (Mont) using the Cd K-edge x-ray absorption spectroscopy (XAS) and isothermal titration calorimetry (ITC). We observed a lower adsorptive capacity for P. putida than B. subtilis, whereas P. putida–Mont and B. subtilis–Mont mixtures showed nearly identical Cd adsorption behaviors. EXAFS fitsmore » and ITC measurements demonstrated more phosphoryl binding of Cd in P. putida. The decreased coordination of C atoms around Cd and the reduced adsorption enthalpies and entropies for the binary mixtures compared to that for individual bacteria suggested that the bidentate Cd-carboxyl complexes in pure bacteria systems were probably transformed into monodentate complexes that acted as ionic bridging structure between bacteria and motmorillonite. This study clarified the binding mechanism of Cd at the bacteria–phyllosilicate interfaces from a molecular and thermodynamic view, which has an environmental significance for predicting the chemical behavior of trace elements in complex mineral–organic systems.« less

  4. Relationship Between Iron Valence States of Serpentine in CM Chondrites and Their Aqueous Alteration Degrees

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Zolensky, M.; Satake, W.; Le, L.

    2012-01-01

    The 0.6-0.7 micron absorption band observed for C-type asteroids is caused by the presence of Fe(3+) in phyllosilicates . Because Fe-bearing phyllosilicates, especially serpentine, are the most dominant product of aqueous alteration in the most abundant carbonaceous chondrites, CM chondrites, it is important to understand the crystal chemistry of serpentine in CM chondrites to better understand spectral features of C-type asteroids. CM chondrites show variable degrees of aqueous alteration, which should be related to iron valences in serpentine. It is predicted that the Fe(3+)/Sum of (Fe) ratios of serpentine in CM chondrites decrease as alteration proceeds by Si and Fe(3+) substitutions from end-member cronstedtite to serpentine, which should be apparent in the absorption intensity of the 0.6-0.7 micron band from C-type asteroids. In fact, the JAXA Hayabusa 2 target (C-type asteroid: 1993 JU3) exhibits heterogeneous spectral features (0.7 micron absorption band disappears by rotation). From these points of view, we have analyzed iron valences of matrix serpentine in several CM chondrites which span the entire observed range of aqueous alteration using Synchrotron Radiation X-ray Absorption Near-Edge Structure (SR-XANES). In this abstract we discuss the relationship between obtained Fe(3+)/Sum of (Fe) ratios and alteration degrees by adding new data to our previous studies

  5. Palagonitic Mars: A Basalt Centric View of Surface Composition and Aqueous Alteration

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Graff, T. G.; Ming, D. W.; Bell, J. F., III; Le, L.; Mertzman, S. A.; Christensen, P. R.

    2004-01-01

    Palagonitic tephra from certain areas on Mauna Kea Volcano (Hawaii) are well-established spectral and magnetic analogues of high-albedo regions on Mars. By definition, palagonite is "a yellow or orange isotropic mineraloid formed by hydration and devitrification of basaltic glass." The yellow to orange pigment is nanometer-sized ferric oxide particles (np-Ox) dispersed throughout the hydrated basaltic glass matrix. The hydration state of the np-Ox particles and the matrix is not known, but the best Martian spectral analogues contain allophane-like materials and not crystalline phyllosilicates. Martian low-albedo regions are also characterized by a palagonite-like ferric absorption edge, but, unlike the highalbedo regions, they also show evidence for absorption by ferrous iron. Thermal emission spectra (TES) obtained by the Mars Global Surveyor Thermal Emission Spectrometer suggest that basaltic (surface Type 1) and andesitic (surface Type 2) volcanic compositions preferentially occur in southern (Syrtis Major) and northern (Acidalia) hemispheres, respectively. The absence of a ferric-bearing component in the modeling of TES spectra is in apparent conflict with VNIR spectra of Martian dark regions, as discussed above. However, the andesitic spectra have also been interpreted as oxidized basalt using phyllosilicates instead of high-SiO2 glass as endmembers in the spectral deconvolution of surface Type 2 TES spectra. We show here that laboratory VNIR and TES spectra of rinds on basaltic rocks are spectral endmembers that provide a consistent explanation for both VNIR and TES data of Martian dark regions.

  6. Spectral parameters for Dawn FC color data: Carbonaceous chondrites and aqueous alteration products as potential cerean analog materials

    NASA Astrophysics Data System (ADS)

    Schäfer, Tanja; Nathues, Andreas; Mengel, Kurt; Izawa, Matthew R. M.; Cloutis, Edward A.; Schäfer, Michael; Hoffmann, Martin

    2016-02-01

    We identified a set of spectral parameters based on Dawn Framing Camera (FC) bandpasses, covering the wavelength range 0.4-1.0 μm, for mineralogical mapping of potential chondritic material and aqueous alteration products on dwarf planet Ceres. Our parameters are inferred from laboratory spectra of well-described and clearly classified carbonaceous chondrites representative for a dark component. We additionally investigated the FC signatures of candidate bright materials including carbonates, sulfates and hydroxide (brucite), which can possibly be exposed on the cerean surface by impact craters or plume activity. Several materials mineralogically related to carbonaceous chondrites, including pure ferromagnesian phyllosilicates, and serpentinites were also investigated. We tested the potential of the derived FC parameters for distinguishing between different carbonaceous chondritic materials, and between other plausible cerean surface materials. We found that the major carbonaceous chondrite groups (CM, CO, CV, CK, and CR) are distinguishable using the FC filter ratios 0.56/0.44 μm and 0.83/0.97 μm. The absorption bands of Fe-bearing phyllosilicates at 0.7 and 0.9 μm in terrestrial samples and CM carbonaceous chondrites can be detected by a combination of FC band parameters using the filters at 0.65, 0.75, 0.83, 0.92 and 0.97 μm. This set of parameters serves as a basis to identify and distinguish different lithologies on the cerean surface by FC multispectral data.

  7. Heavily-hydrated lithic clasts in CH chondrites and the related, metal-rich chondrites Queen Alexandra Range 94411 and Hammadah al Hamra 237

    NASA Astrophysics Data System (ADS)

    Greshake, A.; Krot, A. N.; Meibom, A.; Weisberg, M. K.; Zolensky, M. E.; Keil, K.

    2002-02-01

    Fine-grained, heavily-hydrated lithic clasts in the metal-rich (CB) chondrites Queen Alexandra Range (QUE) 94411 and Hammadah al Hamra 237 and CH chondrites, such as Patuxent Range (PAT) 91546 and Allan Hills (ALH) 85085, are mineralogically similar suggesting genetic relationship between these meteorites. These clasts contain no anhydrous silicates and consist of framboidal and platelet magnetite, prismatic sulfides (pentlandite and pyrrhotite), and Fe-Mn-Mg-bearing Ca-carbonates set in a phyllosilicate-rich matrix. Two types of phyllosilicates were identified: serpentine, with basal spacing of ?0.73 nm, and saponite, with basal spacings of about 1.1-1.2 nm. Chondrules and FeNi-metal grains in CB and CH chondrites are believed to have formed at high temperature (>1300 K) by condensation in a solar nebula region that experienced complete vaporization. The absence of aqueous alteration of chondrules and metal grains in CB and CH chondrites indicates that the clasts experienced hydration in an asteroidal setting prior to incorporation into the CH and CB parent bodies. The hydrated clasts were either incorporated during regolith gardening or accreted together with chondrules and FeNi-metal grains after these high-temperature components had been transported from their hot formation region to a much colder region of the solar nebula.

  8. Mineralogical and geomicrobial examination of soil contamination by radioactive Cs due to 2011 Fukushima Daiichi Nuclear Power Plant accident

    NASA Astrophysics Data System (ADS)

    Akai, Junji; Nomura, Nao; Matsushita, Shin; Kudo, Hisaaki; Fukuhara, Haruo; Matsuoka, Shiro; Matsumoto, Jinko

    Soil contamination by radioactive Cs from Fukushima Daiichi Nuclear Power Plant accident was investigated. Absorption and desorption experiments of Cs were conducted for several phyllosillicates (kaolinite, sericite, montmorillonite, vermiculite, chrysotile and biotite), zeolite and solid organic matter (dead and green leaves). The results confirmed the characteristic sorption and desorption of Cs by these materials. The 2:1 type phyllosilicate, especially, vermiculite and montmorillonite absorbed Cs well. Heated vermiculite for agricultural use and weathered montmorillonite also adsorbed Cs. Leaves also absorbed Cs considerably but easily desorbed it. In summary, the relative capacity and strength of different materials for sorption of Cs followed the order: zeolite (clinoptilolite) > 2:1 type clay mineral > 1:1 type clay mineral > dead and green leaves. Culture experiments using bacteria of both naturally living on dead leaves in Iitate village, Fukushima Pref. and bacterial strains of Bacillus subtillis, Rhodococus erythropolis, Streptomyces aomiensis and Actinomycetospora chlora were carried out. Non-radioactive 1% Cs solution (CsCl) was added to the culture media. Two types of strong or considerable bacterial uptakes of Cs were found in bacterial cells. One is that Cs was contained mainly as globules inside bacteria and the other is that Cs was absorbed in the whole bacterial cells. The globules consisted mainly of Cs and P. Based on all these results, future diffusion and re-circulation behavior of Cs in the surface environment was discussed.

  9. SciT

    Reardon, Patrick N.; Chacon, Stephany S.; Walter, Eric D.

    Proteins facilitate a wide range of chemical transformations important in soil as well as being a major reservoir of soil nitrogen themselves. The interactions and reactions of proteins with soils and minerals are of key importance to our understanding of their functional persistence in the environment. We combined NMR and EPR spectroscopies to distinguish the reaction of a model protein with a redox active mineral surface (Birnessite, MnO 2) from its response to a redox neutral phyllosilicate (Kaolinite). Our data demonstrate that birnessite fragments the model protein while kaolinite has little impact on the protein structure. NMR and EPR spectroscopiesmore » are shown to be valuable tools to observe these reactions and capture the extent of protein transformation together with the extent of mineral response. These data suggest that mineral surfaces can have both promoting and retarding roles in terrestrial nitrogen cycling, with redox active minerals acting as accelerators by catalyzing the breakdown of proteins and proteinaceous materials while phyllosilicates are more likely to act as preservative media.« less

  10. Surface Mineralogy Mapping of Ceres from the Dawn Mission

    NASA Astrophysics Data System (ADS)

    McCord, T. B.; Zambon, F.

    2017-12-01

    Ceres' surface composition is of special interest because it is a window into the interior state and the past evolution of this dwarf planet. Disk-integrated telescopic spectral observations indicated that Ceres' surface is hydroxylated, similar to but not exactly the same as some of the carbonaceous chondrite classes of meteorites. Furthermore, Ceres' bulk density is low, indicating significant water content. The Dawn mission in orbit around Ceres, provided a new and larger set of observations on the mineralogy, molecular and elemental composition, and their distributions in association with surface features and geology. A set of articles was prepared, from which this presentation is derived, that is the first treatment of the entire surface composition of Ceres using the complete High Altitude Mapping Orbit (HAMO) Dawn Ceres data set and the calibrations from all the Dawn instruments. This report provides a current and comprehensive view of Ceres' surface composition and integrates them into general conclusions. Ceres' surface composition shows a fairly uniform distribution of NH4- and Mg-phyllosilicates, carbonates, mixed with a dark component. The widespread presence of phyllosilicates, and salts on Ceres' surface is indicative of the presence of aqueous alteration processes, which involved the whole dwarf planet. There is also likely some contamination by low velocity infall, as seen on Vesta, but it is more difficult to distinguish this infall from native Ceres material, unlike for the Vesta case.

  11. Organic carbon characteristics in density fractions of soils with contrasting mineralogies

    NASA Astrophysics Data System (ADS)

    Yeasmin, Sabina; Singh, Balwant; Johnston, Cliff T.; Sparks, Donald L.

    2017-12-01

    This study was aimed to evaluate the role of minerals in the preservation of organic carbon (OC) in different soil types. Sequential density fractionation was done to isolate particulate organic matter (POM, <1.8 g cm-3) and mineral associated OM (MOM: 1.8-2.2, 2.2-2.6 and >2.6 g cm-3) from four soils, i.e., a Ferralsol, a Luvisol, a Vertisol and a Solonetz. Organic matter (OM) in the density fractions was characterised using diffuse reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and mass spectroscopy in the original states (i.e., without any chemical pre-treatment), and after 6% sodium hypochlorite (NaOCl) and 10% hydrofluoric acid (HF) treatments. The NaOCl oxidation resistant fraction was considered as a relatively stable pool of OC and the HF soluble fraction was presumed as the mineral bound OC. Phyllosilicate-dominated soils, i.e., Vertisol, Luvisol and Solonetz, contained a greater proportion of POM than Fe and Al oxide-dominated Ferralsol. Wider C:N ratio and lower δ13C and δ15N in POM suggest the dominance of labile OC in this fraction and this was also supported by a greater proportion of NaOCl oxidised OC in the same fraction that was enriched with aliphatic C. The sequential density fractionation method effectively isolated OM into three distinct groups in the soils: (i) OM associated with Fe and Al oxides (>1.8 g cm-3 in the Ferralsol); (ii) OM associated with phyllosilicates (1.8-2.6 g cm-3) and (iii) OM associated with quartz and feldspar (>2.6 g cm-3) in the other three soils. Greater oxidation resistance, and more dissolution of OC during the HF treatment in the Fe and Al oxides dominated fractions suggest a greater potential of these minerals to protect OC from oxidative degradation as compared to the phyllosilicates, and quartz and feldspar matrices. OM associated with Fe and Al oxides was predominantly aromatic and carboxylate C. Decreased C:N ratio in the NaOCl oxidation resistant OM and HF soluble OM of

  12. Chemical weathering in a tropical watershed, Luquillo Mountains, Puerto Rico: II. Rate and mechanism of biotite weathering

    Murphy, S.F.; Brantley, S.L.; Blum, A.E.; White, A.F.; Dong, H.

    1998-01-01

    Samples of soil, saprolite, bedrock, and porewater from a lower montane wet forest, the Luquillo Experimental Forest (LEF) in Puerto Rico, were studied to investigate the rates and mechanisms of biotite weathering. The soil profile, at the top of a ridge in the Rio Icacos watershed, consists of a 50-100-cm thick layer of unstructured soil above a 600-800 cm thick saprolite developed on quartz diorite. The only minerals present in significant concentration within the soil and saprolite are biotite, quartz, kaolinite, and iron oxides. Biotite is the only primary silicate releasing significant K and Mg to porewaters. Although biotite in samples of the quartz diorite bedrock is extensively chloritized, chlorite is almost entirely absent in the saprolite phyllosilicates. Phyllosilicate grains are present as 200-1000 ??m wide books below about 50 cm depth. X-ray diffraction (XRD) and electron microprobe analyses indicate that the phyllosilicate grains contain a core of biotite surrounded by variable amounts of kaolinite. Lattice fringe images under transmission electron microscope (TEM) show single layers of biotite altering to two layers of kaolinite, suggesting dissolution of biotite and precipitation of kaolinite at discrete boundaries. Some single 14-A?? layers are also observed in the biotite under TEM. The degree of kaolinitization of individual phyllosilicate grains as observed by TEM decreases with depth in the saprolite. This TEM work is the first such microstructural evidence of epitaxial growth of kaolinite onto biotite during alteration in low-temperature environments. The rate of release of Mg in the profile, calculated as a flux through the soil normalized per watershed land area, is approximately 500 mol hectare-1 yr-1 (1.6 ?? 10-9 molMg m-2soil s-1). This rate is similar to the flux estimated from Mg discharge out the Rio Icacos (1000 mol hectare-1 yr-1, or 3.5 ?? 10-9 molMg m-2soil s-1), indicating that scaling up from the soil to the watershed is

  13. Alteration of Basaltic Glass to Mg/Fe-Smectite under Acidic Conditions: A Potential Smectite Formation Mechanism on Mars

    NASA Technical Reports Server (NTRS)

    Peretyazhko, Tanya; Sutter, Brad; Ming, Douglas W.

    2014-01-01

    Phyllosilicates of the smectite group including Mg- and Fe-saponite and Fe(III)-rich nontronite have been identified on Mars. Smectites are believed to be formed under neutral to alkaline conditions that prevailed on early Mars. This hypothesis is supported by the observation of smectite and carbonate deposits in Noachian terrain on Mars. However, smectite may have formed under mildly acidic conditions. Abundant smectite formations have been detected as layered deposits hundreds of meters thick in intracrater depositional fans and plains sediments, while no large deposits of carbonates are found. Development of mildly acidic conditions at early Mars might allow formation of smectite but inhibit widespread carbonate precipitation. Little is known regarding the mechanisms of smectite formation from basaltic glass under acidic conditions. The objective of this study was to test a hypothesis that Mars-analogue basaltic glass alters to smectite minerals under acidic conditions (pH 4). The effects of Mg and Fe concentrations and temperature on smectite formation from basaltic glass were evaluated. Phyllosilicate synthesis was performed in batch reactors (Parr acid digestion vessel) under reducing hydrothermal conditions at 200 C and 100 C. Synthetic basaltic glass with a composition similar to that of the Gusev crater rock Adirondack (Ground surface APXS measurement) was used in these experiments. Basaltic glass was prepared by melting and quenching procedures. X-ray diffraction (XRD) analysis indicated that the synthesized glass was composed of olivine, magnetite and X-ray amorphous phase. Samples were prepared by mixing 250 mg Adirondack with 0.1 M acetic acid (final pH 4). In order to study influence of Mg concentration on smectite formation, experiments were performed with addition of 0, 1 and 10 mM MgCl2. After 1, 7 and 14 day incubations the solution composition was analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the altered glass and formed

  14. Unraveling the mineralogy of delta deposits on Mars

    NASA Astrophysics Data System (ADS)

    Osterloo, Mikki; Kierein-Young, Kathryn

    2017-04-01

    Detailed geologic characterizations of three of 50+ fan deltas on Mars have yielded important information on their mineralogy as well as formation processes. Data returned from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) have been used to identify spectroscopic signatures consistent with phyllosilicates in fans or deltas within paleolake basins (i.e., Eberswalde, Holden, and Jezero) that indicate sustained subaqueous sediment deposition. Based on these results, two periods of martian history have been identified when the surface or near surface may have been habitable: (1) during the formation of the iron-magnesium smectite clays, likely in the Early Noachian and (2) during the Late Noachian to Early Hesperian fluvial surface activity that led to the formation of Jezero lake. On Earth, rapid deposition of deltaic sediments can preserve organic materials; hence Martian fan deltas may be ideal environments to investigate the past habitability of the planet. Rapid burial coupled with the identification of phyllosilicates within at least some of the martian deltas makes an even more intriguing argument for further investigation of the remainder of deltas. This is because phyllosilicates, and specifically smectite clays, have the ability to trap organic matter in the interlayer sites of their mineral structures and in terrestrial settings are commonly associated with the most organic rich units. Organic materials that were transported into paleolakes would likely have been buried relatively quickly. Hence, the organics would have been protected within the clay-rich deltaic and lacustrine deposits from oxidation and photochemical dissociation. We will present the initial results of a comprehensive study designed to investigate the compositional and mineralogical variability of the remainder of dust-free, previously un-characterized deltas on Mars (of which, there are 33). Our study aims to provide key information regarding differences in formation

  15. Zn isotopes in hydrothermal sulfides and their oxidation products along the south mid-Atlantic ridge: evidence of hydrothermal fluid deposition

    NASA Astrophysics Data System (ADS)

    Li, Xiaohu; Wang, Jianqiang; Chu, Fengyou; Lei, Jijiang; Wang, Hao; Li, Zhenggang

    2018-04-01

    Significant Zn isotope fractionation occurs during seafloor hydrothermal activities. Therefore, exploring variations in Zn isotope composition affected by hydrothermal fluids and oxidative processes would help to better understand hydrothermal fluid cycling and sulfide deposition on mid-ocean ridges. In this paper, the Zn isotope compositions of different types of sulfides and their oxidation products obtained from hydrothermal fields on the South Mid-Atlantic Ridge (13-15°S) were analyzed using a Neptune plus MC-ICP-MS. The δ66Zn ratios range from -0.14‰ to +0.38‰, and the average δ66Zn ratio is +0.12±0.06‰ ( n=21, 2 SD) for all the studied sulfides and oxidation products. The Cu-rich sulfides have a slightly heavier Zn isotope composition (average δ66Zn=+0.19±0.07‰, n=6) than the Zn-rich sulfides (average δ66Zn=-0.02±0.06‰, n=5). The Zn isotope compositions of the oxidation products are similar to those of the Cu-rich sulfides, with an average δ66Zn ratio of 0.14±0.06‰ ( n=10, 2 SD). The Zn isotope compositions of all the samples are generally within the ranges of sulfides from hydrothermal fields on other mid-ocean ridges, such as the East Pacific Rise (9°N, 21°N) and the Trans-Atlantic Geotraverse. However, the average Zn isotope composition indicates the presence of significantly lighter Zn isotopes relative to those reported in the literature (average δ66Zn=+0.39‰). The significant enrichment of the Zn-rich sulfides with light Zn isotopes reveals that kinetic fractionation likely occurs during mineral deposition. Furthermore, the Zn isotope compositions of the sulfides and their oxidation products (average δ66Zn=+0.12‰) are significantly lighter than the average Zn isotope composition of the ocean (δ66Zn=+0.5‰), which could further constrain the modern Zn isotope cycle in the ocean by serving as a sink for light Zn isotopes.

  16. The effect of zinc additions on the environmental stability of Alloy 8090 (Al-Li-Cu-Mg-Zr)

    NASA Technical Reports Server (NTRS)

    Kilmer, Raymond J.; Stoner, G. E.

    1991-01-01

    Stress corrosion cracking (SCC) remains a problem in both Al-Li and conventional Al heat treatable alloys. It has recently been found that relatively small additions (less than or approximately 1 wt-percent) of Zn can dramatically improve the SCC performance of alloy 8090 (Al-Li-Cu-Mg-Zr). Constant load time to failure experiments using cylindrical tensile samples loaded between 30 and 85 percent of TYS indicate improvements of orders of magnitude over the baseline 8090 for the Zn-containing alloys under certain aging conditions. However, the toughnesses of the alloys were noticeably degraded due to the formation of second phase particles which primarily reside on grain and subgrain boundaries. EDS revealed that these intermetallic particles were Cu and Zn rich. The particles were present in the T3 condition and were not found to be the result of quench rate, though their size and distribution were. At 5 hours at 160 C, the alloys displayed the greatest susceptibility to SCC but by 20 hours at 160 C the alloys demonstrated markedly improved TTF lifetimes. Aging past this time did not provide separable TTF results, however, the alloy toughnesses continued to worsen. Initial examination of the alloys microstructures at 5 and 20 hours indicated some changes most notably the S' and delta' distributions. A possible model by which this may occur will be explored. Polarization experiments indicated a change in the trend of E(sub BR) and passive current density at peak aging as compared to the baseline 8090. Initial pitting experiments indicated that the primary pitting mechanism in chloride environments is one occurring at constituent (Al-Fe-Cu) particles and that the Cu and Zn rich boundary precipitates posses a breakaway potential similar to that of the matrix acting neither anodic or cathodic in the first set of aerated 3.5 w/o NaCl experiments. Future work will focus on the identification of the second phase particles, evaluation of K(sub 1SCC) and plateau da/dt via

  17. Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain)

    NASA Astrophysics Data System (ADS)

    Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.

    2009-04-01

    The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged

  18. Variation of mineralogy and organic material during the early stages of aqueous activity recorded in Antarctic micrometeorites

    NASA Astrophysics Data System (ADS)

    Noguchi, T.; Yabuta, H.; Itoh, S.; Sakamoto, N.; Mitsunari, T.; Okubo, A.; Okazaki, R.; Nakamura, T.; Tachibana, S.; Terada, K.; Ebihara, M.; Imae, N.; Kimura, M.; Nagahara, H.

    2017-07-01

    Micrometeorites (MMs) recovered from surface snow near the Dome Fuji Station, Antarctica are almost free from terrestrial weathering and contain very primitive materials, and are suitable for investigation of the evolution and interaction of inorganic and organic materials in the early solar system. We carried out a comprehensive study on seven porous and fluffy MMs [four Chondritic porous (CP) MMs and three fluffy fine-grained (Fluffy Fg) MMs] and one fine-grained type 1 (Fg C1) MM for comparison with scanning electron microscope, transmission electron microscope, X-ray absorption near-edge structure analysis, and secondary ion mass spectrometer. They show a variety of early aqueous activities. Four out of the seven CP MMs contain glass with embedded metal and sulfide (GEMS) and enstatite whiskers/platelets and do not have hydrated minerals. Despite the same mineralogy, organic chemistry of the CP MMs shows diversity. Two of them contain considerable amounts of organic materials with high carboxyl functionality, and one of them contains nitrile (Ctbnd N) and/or nitrogen heterocyclic groups with D and 15N enrichments, suggesting formation in the molecular cloud or a very low temperature region of the outer solar system. Another two CP MMs are poorer in organic materials than the above-mentioned MMs. Organic material in one of them is richer in aromatic C than the CP MMs mentioned above, being indistinguishable from those of hydrated carbonaceous chondrites. In addition, bulk chemical compositions of GEMS in the latter organic poor CP MMs are more homogeneous and have higher Fe/(Si + Mg + Fe) ratios than those of GEMS in the former organic-rich CP MMs. Functional group of the organic materials and amorphous silicate in GEMS in the organic-poor CP MMs may have transformed in the earliest stage of aqueous alteration, which did not form hydrated minerals. Three Fluffy Fg MMs contain abundant phyllosilicates, showing a clear evidence of aqueous alteration

  19. Biosourced Polymetallic Catalysis: A Surprising and Efficient Means to Promote the Knoevenagel Condensation

    PubMed Central

    Deyris, Pierre-Alexandre; Bert, Valérie; Diliberto, Sébastien; Boulanger, Clotilde; Petit, Eddy; Legrand, Yves-Marie; Grison, Claude

    2018-01-01

    Zn hyperaccumulator (Arabidobsis halleri) and Zn accumulator Salix “Tordis” (Salix schwerinii × Salix viminalis) have shown their interest in the phytoextraction of polluted brownfields. Herein, we explore a novel methodology based on the chemical valorization of Zn-rich biomass produced by these metallophyte plants. The approach is based on the use of polymetallic salts derived from plants as bio-based catalysts in organic chemistry. The formed ecocatalysts were characterized via ICP-MS, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) in order to precise the chemical composition, structure, and behavior of the formed materials. The Doebner-Knoevenagel reaction was chosen as model reaction to study their synthetic potential. Significant differences to usual catalysts such as zinc (II) chloride are observed. They can principally be related to a mixture of unusual mineral species. DFT calculations were carried out on these salts in the context of the Gutmann theory. They allow the rationalization of experimental results. Finally, these new bio-based polymetallic catalysts illustrated the interest of this concept for green and sustainable catalysis. PMID:29637065

  20. Biosourced Polymetallic Catalysis: A Surprising and Efficient Means to Promote the Knoevenagel Condensation.

    PubMed

    Deyris, Pierre-Alexandre; Bert, Valérie; Diliberto, Sébastien; Boulanger, Clotilde; Petit, Eddy; Legrand, Yves-Marie; Grison, Claude

    2018-01-01

    Zn hyperaccumulator ( Arabidobsis halleri ) and Zn accumulator Salix "Tordis" ( Salix schwerinii × Salix viminalis ) have shown their interest in the phytoextraction of polluted brownfields. Herein, we explore a novel methodology based on the chemical valorization of Zn-rich biomass produced by these metallophyte plants. The approach is based on the use of polymetallic salts derived from plants as bio-based catalysts in organic chemistry. The formed ecocatalysts were characterized via ICP-MS, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) in order to precise the chemical composition, structure, and behavior of the formed materials. The Doebner-Knoevenagel reaction was chosen as model reaction to study their synthetic potential. Significant differences to usual catalysts such as zinc (II) chloride are observed. They can principally be related to a mixture of unusual mineral species. DFT calculations were carried out on these salts in the context of the Gutmann theory. They allow the rationalization of experimental results. Finally, these new bio-based polymetallic catalysts illustrated the interest of this concept for green and sustainable catalysis.

  1. Biosourced polymetallic catalysis: A surprising and efficient means to promote the Knoevenagel condensation

    NASA Astrophysics Data System (ADS)

    Deyris, Pierre-Alexandre; Bert, Valérie; Diliberto, Sébastien; Boulanger, Clotilde; Petit, Eddy; Legrand, Yves-Marie; Grison, Claude

    2018-03-01

    Zn hyperaccumulator (Arabidobsis halleri) and Zn accumulator Salix ‘Tordis’ (Salix schwerinii x S. viminalis) have shown their interest in the phytoextraction of polluted brownfields. Herein, we explore an innovative methodology based on the chemical valorization of Zn-rich biomass produced by these metallophyte plants. The approach is based on the direct use of polymetallic salts derived from plants as “Lewis acid” catalysts in organic chemistry. The formed ecocatalysts were characterized via ICP-MS, XRD, FT-IR in order to elucidate the chemical composition, structure and behavior of the formed materials. The Doebner-Knoevenagel reaction was chosen as model reaction to study their synthetic potential. Significant differences to conventional catalysts such as zinc (II) chloride are observed. They can principally be related to a mixture of unusual mineral species. DFT calculations were carried out on these salts in the context of the Gutmann theory. They allow the rationalization of experimental results. Finally, these new bio-based polymetallic catalysts illustrated the interest of this concept for green and sustainable catalysis.

  2. Electrophoretic deposition of Cu2ZnSn(S0.5Se0.5)4 films using solvothermal synthesized nanoparticles

    NASA Astrophysics Data System (ADS)

    Badkoobehhezaveh, Amir Masoud; Abdizadeh, Hossein; Golobostanfard, Mohammad Reza

    2018-01-01

    In this paper, a simple, practical, and fast solvothermal route is presented for synthesizing the Cu2ZnSn(S0.5Se0.5)4 nanoparticles (CZTSSe). In this method, the precursors were dissolved in triethylenetetramine and placed in an autoclave at 240 °C for 1 h under controlled pressure and constant stirring. After washing the samples for several times with absolute ethanol, the obtained CZTSSe nanoparticles were successfully deposited on fluorine doped tin oxide substrates by convenient electrophoretic deposition (EPD) using colloidal nanoparticles. The most appropriate parameters for EPD of pre-synthesized CZTSSe nanoparticles which result in proper surface properties, controlled thickness, and high film quality are investigated by adjusting applied voltage, pH, and deposition time. X-ray diffraction pattern and Raman spectroscopy of the pre-synthesized nanoparticles show kesterite structure formation. The particle size of the CZTSSe nanoparticles is in the range of 100 to 400 nm and for some agglomerates, it is about 2 µm confirmed by scanning electron microscope. The deposited film with optimized parameter has acceptable quality without any crack in it with the thickness of about 4-5 µm. Energy-dispersive X-ray spectroscopy confirms that the chemical composition of the samples is in near stoichiometric Cu-poor and Zn-rich region, which guarantees the p-type character of the film. The diffuse reflectance spectroscopy also demonstrates that the optical band gap of the sample is about 1.2 eV.

  3. Mineralogy and chemistry of massive sulfide deposits from the Juan de Fuca Ridge.

    Koski, R.A.; Clague, D.A.; Oudin, E.

    1984-01-01

    Two types of massive sulphide were dredged from one of the six vent sites located in the axial valley of the southern Juan de Fuca ridge. Type A samples are angular slabs of dark grey Zn-rich sulphide with interlayers and a thin, partly-oxidized crust of Fe-sulphide. These layered sulphide aggregates appear to be fragments of a sulphide wall enclosing an active hydrothermal vent. The outer sulphide wall is composed of colloform Fe sulphide and Fe-poor sphalerite deposited under low-T conditions when sea-water and hydrothermal fluid mix above the discharge point. Inside the wall the intensifying hydrothermal sytem deposits a higher-T assemblage of granular Fe-rich sphalerite, wurtzite, pyrite and minor Cu-Fe sulphide. Type B sulphide samples are sub-rounded, spongy-textured fragments composed almost entirely of dendritic aggregates of pale Fe-poor colloform sphalerite and opaline silica. This type of sulphide is deposited in settings peripheral to sites of focused discharge and in open spaces by moderate- to low-T fluid discharging at a slow but variable rate; the fluid becomes increasingly oxidizing, resulting in late-stage deposits of hematite, baryte and sulphur.-L.di H.

  4. Intrinsic point defects in off-stoichiometric Cu2ZnSnSe4: A neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Gurieva, Galina; Valle Rios, Laura Elisa; Franz, Alexandra; Whitfield, Pamela; Schorr, Susan

    2018-04-01

    This work is an experimental study of intrinsic point defects in off-stoichiometric kesterite type CZTSe by means of neutron powder diffraction. We revealed the existence of copper vacancies (VCu), various cation anti site defects (CuZn, ZnCu, ZnSn, SnZn, and CuZn), as well as interstitials (Cui, Zni) in a wide range of off-stoichiometric polycrystalline powder samples synthesized by the solid state reaction. The results show that the point defects present in off-stoichiometric CZTSe agree with the off-stoichiometry type model, assuming certain cation substitutions accounting for charge balance. In addition to the known off-stoichiometry types A-H, new types (I-L) have been introduced. For the very first time, a correlation between the chemical composition of the CZTSe kesterite type phase and the occurring intrinsic point defects is presented. In addition to the off-stoichiometry type specific defects, the Cu/Zn disorder is always present in the CZTSe phase. In Cu-poor/Zn-rich CZTSe, a composition considered as the one that delivers the best photovoltaic performance, mainly copper vacancies, ZnCu and ZnSn anti sites are present. Also, this compositional region shows the lowest degree of Cu/Zn disorder.

  5. Germanium Enrichments in Sedimentary Rocks in Gale Crater, Mars: Constraining the Timing of Alteration and Character of the Protolith

    NASA Technical Reports Server (NTRS)

    Berger, J. A.; Schmidt, M. E.; Gellert, R.; Campbell, J. L.; Boyd, N. I.; Elliott, B. E.; Fisk, M. R.; King, P. L.; Ming, D. W.; Perrett, G. M.; hide

    2015-01-01

    Rocks enriched in Ge have been discovered in Gale Crater, Mars, by the Alpha-particle X-ray spectrometer (APXS) on the Mars Science Lab (MSL) rover, Curiosity. The Ge concentrations in Gale Crater (commonly >50 ppm) are remarkably high in comparison to Earth, where Ge ranges from 0.5-4.0 ppm in igneous rocks and 0.2-3.3 ppm in siliciclastic sediment. Primary meteoritic input is not likely the source of high Ge because Ge/Ni in chondrites (approx.0.003) and irons (<0.04) is lower than in Gale rocks (0.08-0.2). Earth studies show Ge is a useful geochemical tracer because it is coherent with Si during magmatic processes and Ge/Si varies less than 20% in basalts. Ge and Si fractionate during soil/regolith weathering, with Ge preferentially sequestered in clays. Ge is also concentrated in Cu- and Zn-rich hydrothermal sulfide deposits and Fe- and Mnrich oxide deposits. Other fluid-mobile elements (K, Zn, Cl, Br, S) are also enriched at Gale and further constrain aqueous alteration processes. Here, we interpret the sediment alteration history and present a possible model for Ge enrichments at Gale involving fluid alteration of the protolith.

  6. Tuning the nanostructures and optical properties of undoped and N-doped ZnO by supercritical fluid treatment

    NASA Astrophysics Data System (ADS)

    Li, Yaping; Wang, Hui-Qiong; Chu, Tian-Jian; Li, Yu-Chiuan; Li, Xiaojun; Liao, Xiaxia; Wang, Xiaodan; Zhou, Hua; Kang, Junyong; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zheng, Jin-Cheng

    2018-05-01

    Treatment of ZnO films in a supercritical fluid (SCF) has been reported to improve the performance of devices in which the treated ZnO films are incorporated; however, the mechanism of this improvement remains unclear. In this paper, we study the transformation of the surface morphologies and emission properties of ZnO films before and after SCF treatment, establishing the relationship between the treated and untreated structures and thereby enabling tuning of the catalytic or opto-electronic performance of ZnO films or ZnO-film-based devices. Both undoped and N-doped ZnO nanostructures generated by SCF treatment of films are investigated using techniques to characterize their surface morphology (scanning electron microscopy (SEM) and atomic force microscopy (AFM)) as well as room-temperature photoluminescence (RT-PL) spectroscopy. The water-mixed supercritical CO2 (W-SCCO2) technology was found to form nanostructures in ZnO films through a self-catalyzed process enabled by the Zn-rich conditions in the ZnO films. The W-SCCO2 was also found to promote the inhibition of defect luminescence by introducing -OH groups onto the films. Two models are proposed to explain the effects of the treatment with W-SCCO2. This work demonstrates that the W-SCCO2 technology can be used as an effective tool for the nanodesign and property enhancement of functional metal oxides.

  7. Effects of hydrogen on acceptor activation in ternary nitride semiconductors

    DOE PAGES

    Fioretti, Angela N.; Stokes, Adam; Young, Matthew R.; ...

    2017-02-09

    Doping control is necessary to unlock the scientific and technological potential of many materials, including ternary II-IV-nitride semiconductors, which are closely related to binary GaN. In particular, ZnSnN 2 has been reported to have degenerate doping density, despite bandgap energies that are well suited for solar energy conversion. Here, we show that annealing Zn-rich Zn 1+xSn 1-xN 2 grown with added hydrogen reduces its free electron density by orders of magnitude, down to 4 x 10 16 cm -3. This experimental observation can be explained by hydrogen passivation of acceptors in Zn 1+xSn 1-xN 2 during growth, lowering the drivingmore » force for unintentional donor formation. Lastly, these results indicate that the doping control principles used in GaN can be translated to ZnSnN 2, suggesting that other strategies used in binary III-Vs can be applied to accelerate the technological development of ternary II-IV-N 2 materials.« less

  8. Zinc isotopic composition of particulate matter generated during the combustion of coal and coal + tire-derived fuels.

    PubMed

    Borrok, David M; Gieré, Reto; Ren, Minghua; Landa, Edward R

    2010-12-01

    Atmospheric Zn emissions from the burning of coal and tire-derived fuel (TDF) for power generation can be considerable. In an effort to lay the foundation for tracking these contributions, we evaluated the Zn isotopes of coal, a mixture of 95 wt % coal + 5 wt % TDF, and the particulate matter (PM) derived from their combustion in a power-generating plant. The average Zn concentrations and δ(66)Zn were 36 mg/kg and 183 mg/kg and +0.24‰ and +0.13‰ for the coal and coal + TDF, respectively. The δ(66)Zn of the PM sequestered in the cyclone-type mechanical separator was the lightest measured, -0.48‰ for coal and -0.81‰ for coal+TDF. The δ(66)Zn of the PM from the electrostatic precipitator showed a slight enrichment in the heavier Zn isotopes relative to the starting material. PM collected from the stack had the heaviest δ(66)Zn in the system, +0.63‰ and +0.50‰ for the coal and coal + TDF, respectively. Initial fractionation during the generation of a Zn-rich vapor is followed by temperature-dependent fractionation as Zn condenses onto the PM. The isotopic changes of the two fuel types are similar, suggesting that their inherent chemical differences have only a secondary impact on the isotopic fractionation process.

  9. Size tuned polyol-made Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles as potential heating agents for magnetic hyperthermia: from synthesis control to toxicity survey

    NASA Astrophysics Data System (ADS)

    Basti, H.; Hanini, A.; Levy, M.; Ben Tahar, L.; Herbst, F.; Smiri, L. S.; Kacem, K.; Gavard, J.; Wilhelm, C.; Gazeau, F.; Chau, F.; Ammar, S.

    2014-12-01

    Zn-rich substituted Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles (NPs) of about 5 and 10 nm were produced by the so-called polyol method. They were engineered for hyperthermia therapy based on their magnetic and morphological properties. Indeed, because of their comparatively low Curie temperature and reasonable magnetization, these probes may turn into useful self-regulated heating agents under suitable conditions. For such a purpose, the structure, the microstructure, the magnetic and magnetocalorimetric properties of the produced NPs as well as their in vitro cytotoxicity were investigated. Our results demonstrate that the magnetic properties of these magnetically diluted spinel ferrite particles can be largely modified by just changing their size. They also show that the about 10 nm sized manganese-based ones exhibit the highest heating power under a 700 kHz ac magnetic field and the lowest cytotoxicity on Immortalized human umbilical vascular endothelial cells (HUVEC).

  10. High-Temperature Active Soldering of SiC Particle-Reinforced Al-MMC Using a Novel ZnAlGaMgTi Filler Metal

    NASA Astrophysics Data System (ADS)

    Chen, Biqiang; Zhang, Guifeng; Zhang, Linjie; Xu, Tingting

    2017-10-01

    In order to broaden the application of SiC particle-reinforced aluminum matrix composite in electronics packaging, newly developed ZnAlGaMgTi filler with a low melting point of 418-441 °C was utilized as filler metal for active soldering of aluminum matrix composites (70 vol.%, SiCp/Al-MMCs) for the first time. The effect of loading pressure on joint properties of ZnAlGaMgTi active filler was investigated. The experimental results indicated that novel filler could successfully solder Al-MMCs, and the presence of Mg in the filler enhanced the penetration of Zn, while the forming of Zn-rich barrier layer influenced the active element MPD (melting point depressant) diffusion into parent composite, and the bulk-like (Mg-Si)-rich phase and Ti-containing phase were readily observed at the interface and bond seam. With the increase in loading pressure, the runout phenomenon appeared more significant, and the filler foil thickness and the Zn penetration depth varied pronouncedly. Sound joints with maximum shear strength of 29.6 MPa were produced at 480 °C at 1 MPa, and the crack occurred adjacent to the boundary of SiC particle and then propagated along the interface. A novel model describing the significant mutual diffusion of Al and Zn atoms between the parent material and solder was proposed.

  11. Structural and electrical properties of Zn1.10CuxMn1.90-xO4 (0 ≤ x ≤ 0.15) for application in IR detectors

    NASA Astrophysics Data System (ADS)

    Kim, Kyeong-Min; Lee, Sung-Gap; Lee, Dong-Jin; Kwon, Min-Su

    2017-05-01

    In this study, Zn1.10CuxMn1.90-xO4 (0 ≤ x ≤ 0.15) systems were prepared through the conventional solid state reaction method. All specimens were sintered in air at 1200 °C for 12 h and cooled at a rate of 2 °C/min to 800 °C, subsequently quenching to room temperature. Structural investigations were carried out using X-ray diffraction patterns and energy dispersive spectrometry. For x ≥ 0.10, formation of a tetragonal phase with a Zn-rich Zn-Cu-Mn-O segregated second phase was observed. In the microstructure, the grain size increased from 5.10 μm to 9.68 μm with an increase in Cu content. The resistivity at room temperature, B-value, responsivity and detectivity of the Zn1.10Cu0.05Mn1.85O4 specimen were found to be 300.2 kΩ·cm, 4665, 0.025 V/W, and 2.12 ×104 cmHz1/2/W, respectively. [Figure not available: see fulltext.

  12. Rapid growth of mineral deposits at artificial seafloor hydrothermal vents

    PubMed Central

    Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken

    2016-01-01

    Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes vented hydrothermal fluids in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal vent more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal fluids with the ambient seawater. PMID:26911272

  13. Zinc isotopic composition of particulate matter generated during the combustion of coal and coal + tire-derived fuels

    Borrok, D.M.; Gieré, R.; Ren, M.; Landa, E.R.

    2010-01-01

    Atmospheric Zn emissions from the burning of coal and tire-derived fuel (TDF) for power generation can be considerable. In an effort to lay the foundation for tracking these contributions, we evaluated the Zn isotopes of coal, a mixture of 95 wt % coal + 5 wt % TDF, and the particulate matter (PM) derived from their combustion in a power-generating plant. The average Zn concentrations and δ(66)Zn were 36 mg/kg and 183 mg/kg and +0.24‰ and +0.13‰ for the coal and coal + TDF, respectively. The δ(66)Zn of the PM sequestered in the cyclone-type mechanical separator was the lightest measured, -0.48‰ for coal and -0.81‰ for coal+TDF. The δ(66)Zn of the PM from the electrostatic precipitator showed a slight enrichment in the heavier Zn isotopes relative to the starting material. PM collected from the stack had the heaviest δ(66)Zn in the system, +0.63‰ and +0.50‰ for the coal and coal + TDF, respectively. Initial fractionation during the generation of a Zn-rich vapor is followed by temperature-dependent fractionation as Zn condenses onto the PM. The isotopic changes of the two fuel types are similar, suggesting that their inherent chemical differences have only a secondary impact on the isotopic fractionation process.

  14. The effects of Pantoea sp. strain Y4-4 on alfalfa in the remediation of heavy-metal-contaminated soil, and auxiliary impacts of plant residues on the remediation of saline-alkali soils.

    PubMed

    Li, Shuhuan; Wang, Jie; Gao, Nanxiong; Liu, Lizhu; Chen, Yahua

    2017-04-01

    The plant-growth-promoting rhizobacterium (PGPR) Y4-4 was isolated from plant rhizosphere soil and identified as Pantoea sp. by 16S rRNA sequence analysis. The effects of strain Y4-4 on alfalfa grown in heavy-metals-contaminated soil was investigated using a pot experiment. In a Cu-rich environment, the shoot dry mass and total dry mass of plants inoculated with strain Y4-4 increased by 22.6% and 21%, and Cu accumulation increased by 15%. In a Pb-Zn-rich environment, the shoot dry mass and total dry mass of plants inoculated with strain Y4-4 increased by 23.4% and 22%, and Zn accumulation increased by 30.3%. In addition, the salt tolerance and biomass of wheat seedlings could be improved by applying strain Y4-4 mixed with plant residue as a result of the Cu-rich plant residues providing copper nutrition to wheat. This study offers an efficient PGPR with strong salt tolerance and a safe strategy for the post-treatment of plant residue.

  15. Faunal composition and organic surface encrustations at hydrothermal vents on the southern Juan De Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Tunnicliffe, Verena; Fontaine, A. R.

    1987-10-01

    Examination of a small collection of macroinvertebrates from three vents of the southern Juan de Fuca vent field reveals differences between the vents with respect to species composition, species habits, and microbial and metallic deposits on their surfaces. TWo apparently new vestimentiferan species were found, and for the first time the Juan de Fuca palm worm was observed to dwell on smokers. High acidity values recorded in this system may interfere with the process of shell calcification in an archaeogastropod snail. The surfaces of vestimentifer an tubes at two vents are heavily encrusted with microbial and metallic accumulations. Scanning electron microscope, transmission electron microscope, and energy dispersive X ray microanalysis observations show that iron-based crusts on orange tubes are built from accumulations of an Fe-rich particle of distinctive size and shape. Morphological evidence is presented for the microbial origin of Fe-rich particles. Zn-rich particles found on black tubes are not of microbial origin. We suggest that iron deposition on surfaces in the vent environment is initially biocatalytic but subsequent deposits may build by simple inorganic reactions.

  16. Particulate matter analysis at elementary schools in Curitiba, Brazil.

    PubMed

    Avigo, Devanir; Godoi, Ana F L; Janissek, Paulo R; Makarovska, Yaroslava; Krata, Agnieszka; Potgieter-Vermaak, Sanja; Alfoldy, Balint; Van Grieken, René; Godoi, Ricardo H M

    2008-06-01

    The particulate matter indoors and outdoors of the classrooms at two schools in Curitiba, Brazil, was characterised in order to assess the indoor air quality. Information concerning the bulk composition was provided by energy-dispersive x-ray fluorescence (EDXRF). From the calculated indoor/outdoor ratios and the enrichment factors it was observed that S-, Cl- and Zn-rich particles are of concern in the indoor environment. In the present research, the chemical compositions of individual particles were quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis low Z EPMA. Samples were further analysed for chemical and morphological aspects, determining the particle size distribution and classifying them according to elemental composition associations. Five classes were identified based on major elemental concentrations: aluminosilicate, soot, organic, calcium carbonate and iron-rich particles. The majority of the respirable particulate matter found inside of the classroom was composed of soot, biogenic and aluminosilicate particles. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the human respiratory system were calculated revealing the deposition of soot at alveolar level. The results showed that on average 42% of coarse particles are deposited at the extrathoracic level, whereas 24% are deposited at the pulmonary region. The fine fraction showed a deposition rate of approximately 18% for both deposition levels.

  17. Ca:Mg:Zn:CO3 and Ca:Mg:CO3-tri- and bi-elemental carbonate microparticles for novel injectable self-gelling hydrogel-microparticle composites for tissue regeneration.

    PubMed

    Douglas, Timothy E L; Sobczyk, Katarzyna; Łapa, Agata; Włodarczyk, Katarzyna; Brackman, Gilles; Vidiasheva, Irina; Reczyńska, Katarzyna; Pietryga, Krzysztof; Schaubroeck, David; Bliznuk, Vitaliy; Voort, Pascal Van Der; Declercq, Heidi A; Bulcke, Jan Van den; Samal, Sangram Keshari; Khalenkow, Dmitry; Parakhonskiy, Bogdan V; Van Acker, Joris; Coenye, Tom; Lewandowska-Szumieł, Małgorzata; Pamuła, Elżbieta; Skirtach, Andre G

    2017-03-24

    Injectable composites for tissue regeneration can be developed by dispersion of inorganic microparticles and cells in a hydrogel phase. In this study, multifunctional carbonate microparticles containing different amounts of calcium, magnesium and zinc were mixed with solutions of gellan gum (GG), an anionic polysaccharide, to form injectable hydrogel-microparticle composites, containing Zn, Ca and Mg. Zn and Ca were incorporated into microparticle preparations to a greater extent than Mg. Microparticle groups were heterogeneous and contained microparticles of differing shape and elemental composition. Zn-rich microparticles were 'star shaped' and appeared to consist of small crystallites, while Zn-poor, Ca- and Mg-rich microparticles were irregular in shape and appeared to contain lager crystallites. Zn-free microparticle groups exhibited the best cytocompatibility and, unexpectedly, Zn-free composites showed the highest antibacterial activity towards methicilin-resistant Staphylococcus aureus. Composites containing Zn-free microparticles were cytocompatible and therefore appear most suitable for applications as an injectable biomaterial. This study proves the principle of creating bi- and tri-elemental microparticles to induce the gelation of GG to create injectable hydrogel-microparticle composites.

  18. Crystallographic Texture and Elemental Composition Mapped in Bovine Root Dentin at the 200 nm Level

    PubMed Central

    Deymier-Black, A. C.; Veis, A.; Cai, Z.; Stock, S. R.

    2015-01-01

    Summary The relationship between the mineralization of peritubular dentin (PTD) and intertubular dentin (ITD) is not well understood. Tubules are quite small, diameter ~2 μm, and this makes the near-tubule region of dentin difficult to study. Here, advanced characterization techniques are applied in a novel way to examine what organic or nanostructural signatures may indicate the end of ITD or the beginning of PTD mineralization. X-ray fluorescence intensity (Ca, P, and Zn) and X-ray diffraction patterns from carbonated apatite (cAp) were mapped around dentintubules at resolutions ten times smaller than the feature size (200 nm pixels), representing a 36% increase in resolution over earlier work. In the near tubule volumes of near-pulp, root dentin, Zn intensity was higher than in ITD remote from the tubules. This increase in Zn2+, as determined by X-ray absorption near edge structure analysis, may indicate the presence of metalloenzymes or transcription factors important to ITD or PTD mineralization. The profiles of the cAp 00.2 X-ray diffraction rings were fitted with a pseudo-Voigt function, and the spatial and azimuthal distribution of these rings’ integrated intensities indicated that the cAp platelets were arranged with their c-axes aligned tangential to the edge of the tubule lumen. This texture was continuous throughout the dentin indicating a lack of structural difference between in the Zn rich near-tubular region and the remote ITD. PMID:23630059

  19. Abundant defects and defect clusters in kesterite Cu2ZnSnS4 and Cu2ZnSnSe4

    NASA Astrophysics Data System (ADS)

    Chen, Shiyou; Wang, Lin-Wang; Walsh, Aron; Gong, Xin-Gao; Wei, Su-Huai

    2013-03-01

    Cu2ZnSnS4 and Cu2ZnSnSe4 are drawing intensive attention as the light-absorber materials in thin-film solar cells. A large variety of intrinsic defects can be formed in these quaternary semiconductors, which have important influence on their optical and electrical properties, and hence their photovoltaic performance. We will present our first-principles calculation study on a series of intrinsic defects and defect clusters in Cu2ZnSnS4 and Cu2ZnSnSe4, and discuss: (i) strong phase-competition between the kesterites and the coexisting secondary compounds; (ii) the dominant CuZn antisites and Cu vacancies which determine the intrinsic p-type conductivity, and their dependence on the elemental ratios; (iii) the high population of charge-compensated defect clusters (like VCu + ZnCu and 2CuZn + SnZn) and their contribution to non-stoichiometry ; (iv) the deep-level defects which act as recombination centers. Based on the calculation, we will explain the experimental observation that Cu poor and Zn rich conditions give the highest solar cell efficiency, as well as suggesting an efficiency limitation in Cu2ZnSn(S,Se)4 cells with high S composition. Supported by NSF of China, JCAP: a U.S. DOE Energy Innovation Hub, Royal Society of U.K. and EPSRC, and U.S. DOE.

  20. Broad range tuning of structural and optical properties of Zn x Mg1-x O nanostructures grown by vapor transport method

    NASA Astrophysics Data System (ADS)

    Vanjaria, Jignesh V.; Azhar, Ebraheem Ali; Yu, Hongbin

    2016-11-01

    One-dimensional (1D) Zn x Mg1-x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results.

  1. Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention.

    PubMed

    Li, M Y; Yang, H F; Zhang, Z H; Gu, J H; Yang, S H

    2016-06-08

    A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder.

  2. Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention

    PubMed Central

    Li, M. Y.; Yang, H. F.; Zhang, Z. H.; Gu, J. H.; Yang, S. H.

    2016-01-01

    A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder. PMID:27273421

  3. Mineralogy, chemical composition and structure of the MIR Mound, TAG Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Stepanova, T. V.; Krasnov, S. G.; Cherkashev, G. A.

    The study of samples collected from the surface of the MIR mound (TAG Hydrothermal Field) by video-controlled hydraulic grab allowed identification of a number of mineralogical types. These include pyrite-chalcopyrite (Py-Cp), bornite-chalcopyrite-opaline (Bn-Cp-Op) and sphalerite-opaline (Sp-Op) sulfide chimneys, massive sulfides composed of pyrite (Py), chalcopyrite-pyrite (Cp-Py), marcasite-pyrite-opaline (Mc-Py-Op), sphalerite-pyrite-opaline (Sp-Py-Op) and sphalerite-chalcopyrite-pyrite-opaline (Sp-Cp-Py-Op), as well as siliceous and Fe-Mn oxide hydrothermal deposits. Most of the minor elements (Ag, Au, Cd, Ga, Hg, Sb and Pb) are associated with Zn-rich massive sulfides, Co Bi, Pb, and As with Ferich ones, while Cu-rich sulfides are depleted of trace metals. Cu-enriched assemblages are concentrated in the northern part, Zn-enriched in the center, and siliceous rocks in the south of the MIR mound. According to paragenetic relations, the development of the mound started with the formation of quartz (originally opaline) rocks and dendritic assemblages of melnikovite-pyrite, followed by deposition of chalcopyrite and recrystallization of primary pyrite, subsequent generation of sphalerite-rich assemblages and final deposition of opaline rocks. The late renewal of hydrothermal activity led to local formation of Cu-rich chimneys enriched in Au, Ag, Hg and Pb probably due to their remobilization from inner parts of the deposit.

  4. The influence of the precursor compositional ratio on Cu2ZnSnS4 films prepared by using sulfurization of the metallic precursor

    NASA Astrophysics Data System (ADS)

    Amal, Muhamad I.; Kim, Kyoo Ho

    2013-12-01

    Cu2ZnSnS4 (CZTS) films were prepared by using the sulfurization of sputtered metallic precursors. The compositional ratio of the CZTS films was slightly different compared to their initial metallic precursors due to elemental loss during annealing. The Cu/(Zn+Sn) ratio for the CZTS-1, CZTS-2 and CZTS-3 films were 0.91, 1.06 and 1.21, respectively. In addition, all films had a compositional ratio of Zn/Sn >1. The grain sizes of the CZTS films increased with increasing Cu ratio. X-ray diffraction and Raman spectroscopy showed that the CZTS films with an excess of copper and zinc had secondary phases of Cu2SnS3 and ZnS. The optical band gap and absorption coefficient for all CZTS films in the range of the experimental compositions were calculated to be 1.5 eV and >104 cm-1, respectively. The presence of secondary phases related to compositional ratio in the CZTS films influenced the electrical properties. The CZTS-1 film with a Cu-poor and Zn-rich composition whose a carrier concentration, an electrical mobility, and a resistivity values were 2.29 × 1018 cm-3, 10.29 cm2 V-1 s-1, 3.16 Ω cm, is the most suitable for solar-cell applications.

  5. Evolution of organic matter in Orgueil, Murchison and Renazzo during parent body aqueous alteration: In situ investigations

    NASA Astrophysics Data System (ADS)

    Le Guillou, Corentin; Bernard, Sylvain; Brearley, Adrian J.; Remusat, Laurent

    2014-04-01

    Chondrites accreted the oldest solid materials in the solar system including dust processed in the protoplanetary disk and diverse organic compounds. After accretion, asteroidal alteration may have impacted organic particles in various ways. To constrain these processes, we conducted a comprehensive study of organics disseminated within the matrices of the three carbonaceous chondrite falls, Renazzo (CR2), Murchison (CM2) and Orgueil (CI). By combining synchrotron-based STXM and TEM analyses on FIB sections of samples previously characterized by NanoSIMS, we investigated the influence of aqueous alteration on the morphology, isotopic signature, molecular structure, spatial distribution, and mineralogical environment of the organic matter within the matrices. Two different populations of materials are distinguishable: sub-micrometric individual grains, likely dominated by insoluble compounds and diffuse organic matter, finely interspersed within phyllosilicates and/or (amorphous) nanocarbonates at the nanometer scale. We suggest that this latter component, which is depleted in aromatics and enriched in carboxylic functional groups, may be dominated by soluble compounds. Organic matter in Renazzo (CR) mainly consists of chemically-homogeneous individual grains surrounded by amorphous and nanocrystalline phyllosilicates. Evidence of connectivity between organic grains and fractures indicates that redistribution has occurred: some areas containing diffuse organic matter can be observed. This diffuse organic component is more abundant in Murchison (CM) and Orgueil (CI). This is interpreted as resulting from fluid transport at the micrometer scale and encapsulation within recrystallized alteration phases. In contrast to Renazzo, organic grains in Murchison and Orgueil display strong chemical heterogeneities, likely related to chemical evolution during aqueous alteration. The observations suggest that the altering fluid was a brine with elevated concentrations of both

  6. Mid-Infrared Study of Samples from Multiple Stones from the Sutters Mill Meteorite

    NASA Technical Reports Server (NTRS)

    Sandford, S. A.; Nuevo, M.; Flynn, G. J.; Wirick, S.

    2013-01-01

    The Sutter's Mill meteorite fell in N. California on April 22, 2012 and numerous pieces have been recovered and studied. We present Fourier transform infrared (FTIR) spectra of fragments from several stones of the meteorite. Methods and analysis: Infrared spectra of the samples were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-675/cm; spectral resolution 4/cm). All samples were deposited on a clean glass slide, crushed with a stainless steel roller tool, and placed directly on the focal plane of the microscope. IR spectra were collected by averaging 128 scans. Results: Preliminary IR spectra of the non-fusion crust samples show mineral compositions that are dominated by phyllosilicates, carbonates, or mixtures of both [2]. The carbonates display a dominant, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm). Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands. The O-H shows up in two forms (1) a broadband centered at 3415/cm that is probably largely due to adsorbed H2O and (2) a much weaker, narrower feature centered near 3680/cm due to structural -OH. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. The relative intensities of the bands in this range are somewhat unusual. Typically, the asymmetric aliphatic CH stretching bands are stronger than the symmetric stretching bands, but in this case the reverse is true. This unusual pattern is well matched by the aliphatic features seen in the spectrum of a terrestrial calcite (CaCO3) standard. This observation, and the fact that the strength of the carbonate and aliphatic bands seem to correlate, suggest the organics are associated with the carbonates. Conclusions: IR spectra of samples from the Sutter's Mill meteorite show absorption features associated with carbonates, phyllosilicates, and organics. Both

  7. Diverse Aqueous Conditions on Mars from New Orbital Detections of Carbonate and Sulfate

    NASA Astrophysics Data System (ADS)

    Wray, James J.; Squyres, S. W.

    2010-10-01

    Diverse aqueous environments on ancient Mars have been a key inference from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on NASA's Mars Reconnaissance Orbiter, which has identified many alteration minerals in a range of settings [e.g., 1-4]. Here we report two new minerals detected using CRISM. In the southern highlands northwest of the Hellas basin, a mid-sized crater exposes carbonate in its central uplift. Spectral absorptions at 1, 2.33, and 2.53 microns are most consistent with Fe-carbonate, distinct from the Mg-carbonates identified from orbit by [5]. Fe-carbonate is associated with Mg-phyllosilicate in fractured materials formerly buried kilometers beneath the surface, and--like the Mg/Fe-carbonate found by the Spirit rover [6]--suggests a reducing, neutral-to-alkaline alteration environment. One of the largest phyllosilicate exposures on Mars occurs in the Mawrth Vallis region [e.g., 7]. We identify bassanite (Ca-sulfate hemihydrate) in layers underlying the phyllosilicate-bearing beds [8], a stratigraphy distinct from that predicted by global models of martian aqueous history [9]. Bassanite could have formed via acid-sulfate alteration of Ca-carbonate, through dehydration of gypsum, or under hydrothermal conditions [10]. These detections expand the known mineralogic diversity of Mars and the range of environments to explore for past habitability. [1] Mustard, J. F. et al. (2008) Nature 454, 305-309. [2] Murchie, S. L. et al. (2009) J. Geophys. Res. 114, E00D06. [3] Ehlmann, B. L. et al. (2009) J. Geophys. Res. 114, E00D08. [4] Wray, J. J. et al. (2009) Geology 37, 1043-1046. [5] Ehlmann, B. L. et al. (2008) Science 322, 1828-1832. [6] Morris, R. V. et al. Science, in press, doi:10.1126/science.1189667. [7] Poulet, F. et al. (2005) Nature 438, 623-627. [8] Wray, J. J. et al. Icarus, in press, doi:10.1016/j.icarus.2010.06.001. [9] Bibring, J.-P. et al. (2006) Science 312, 400-404. [10] Vaniman, D. T. et al. (2009) LPSC 40, 1654.

  8. Characterizing Mafic, Clay, and Carbonate Components found in MRO/CRISM Images in Libya Montes, Mars, using Advances in Automated Gaussian Modeling of Spectral Features

    NASA Astrophysics Data System (ADS)

    Makarewicz, H. D.; Parente, M.; Perry, K. A.; McKeown, N. K.; Bishop, J. L.

    2009-12-01

    Aqueous processes have been inferred at the Libya Montes rim/terrace complex of the southern Isidis Basin due to the dense concentration of valley networks [1]. Coordinated CRISM-HiRISE investigations of this region characterized discrete units of ancient phyllosilicate deposits covered by an olivine-rich material and a pyroxene caprock [2]. CRISM mapping data show minor phyllosilicate abundances widespread throughout the Southern Highlands [3], which are dominated by low-Ca pyroxene bearing material [4,5]. The carbonate magnesite has also been located throughout this area [6] and at Libya Montes [7]. Our current study involves detailed characterization of the minerals present at Libya Montes through implementation of improved automated Gaussian modeling methods. We have developed an automated procedure for modeling spectral features using Gaussians that has been successfully applied to laboratory studies and hyperspectral analyses of Mars [8,9,10,11]. Several studies are being conducted to improve and validate these models. These include a comparison of initialization methods, continuum methods, optimization algorithms, and modeled functions. The modeled functions compared include Gaussians, saturated Gaussians, and Lorentzians. This algorithm and the modeling studies are currently being applied towards analyses of CRISM hyperspectral images of Libya Montes and laboratory spectra of mineral mixtures. Specifically, olivine, pyroxene, phyllosilicate, and carbonate deposits are being modeled and classified by composition in CRISM images. References [1]Crumpler, L. S., and K. L. Tanaka (2003) J. Geophys. Res., 108, DOI: 8010.1029/2002JE002040. [2]Bishop, J. L., et al. (2007) 7th Int'l Mars Conf. [3]Mustard, J. F., et al. (2008) Nature, 454, 07305. [4]Bibring, J.-P., et al. (2005) Science, 307,1576. [5]Mustard, J. F., et al.(2005) Science, 307, 1594. [6]Ehlmann, B. L., et al. (2008) Science, 322, 1828. [7]Perry, K., et al. (2009) AGU Fall Mtng. [8]Makarewicz, H. D., et

  9. Spectral classification and mineralogical characterization of Nili Fossae for a better understanding of hydrated mineralogies.

    NASA Astrophysics Data System (ADS)

    Serventi, Giovanna; Carli, Cristian; Altieri, Francesca; Geminale, Anna; Sgavetti, Maria; Grassi, Davide; Orosei, Roberto; Bellucci, Giancarlo

    2017-04-01

    The presence of hydrated minerals on Mars provides a record of water-related processes and, in particular, the identification of phyllosilicates puts constraints on the evolution of Mars (Poulet et al., 2005). Even if data from the Observatoire pour la Minèralogie, l'Eau, les Glaces, et l'Activitè (OMEGA) and from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) show the presence of different hydrated minerals, on Mars the spectral regions where hydrated minerals absorb are also affected by atmospheric features due to gaseous components, mostly CO2 and H2O. Among the different methods that have been proposed to separate the atmospheric signatures from the hydrated absorptions, we use the Surface Atmosphere Separation (SAS) method proposed by Geminale et al. (2015) to analyze the Nili Fossae region (in particular, four MEX orbit have been selected and a mosaic have been created). In this work, we spectrally classify the Nili Fossae region using the Spectral Angle Mapping (SAM, Kruse et al., 1993) classification and using a spectral library iteratively built from the image though the Pixel Purity Index (PPI, Boardman, 1995). Mainly, we recognized five spectral regions dominated by: iron-hydroxides, pyroxenes (both orthopyroxene and clinopyroxene), olivine and phyllosilicates, in accordance with the literature. Then, we focused on the hydrated regions: absorptions in the 1.9-2.3 µm are fundamental to recognize a hydrated mineralogy, and to discriminate between phyllosilicates characterized by different cations in the octahedral environment. Comparing our results with maps from Mangold et al. (2007) and Poulet et al (2007), we demonstrated that the SAS+SAM technique permits to identify hydrated regions that cannot be easily recognized using the spectral mapping applied to images corrected with Mons Olympus method (Langevin et al., 2005). Furthermore, applying the MGM algorithm to a set of spectra selected from hydrated regions, we recognized the

  10. Science Results from a Mars Drilling Simulation (Río Tinto, Spain) and Ground Truth for Remote Science Observations

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, Rosalba; Stoker, Carol R.

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. Science results. Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (˜1:1, ˜1:2, and ˜1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (Corg <0.05 wt %) beneath the biologically active organic-rich soil horizon (Corg ˜3-11 wt %) in contrast to the phyllosilicate-rich zones (Corg ˜0.23 wt %). Ground truth vs. remote science analysis. Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5‧-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all cores. Our manned vs. remote observations based on automated

  11. Investigating Hydroxyl at Asteroid 951 Gaspra

    NASA Astrophysics Data System (ADS)

    Granahan, James C.

    2015-11-01

    Recent investigations [Granahan, 2011; 2014] of Galileo Near Infrared Mapping Spectrometer (NIMS) observations of asteroid 951 Gaspra have detected an infrared absorption feature near 2.8 micrometers. These were detected in NIMS data acquired by the Galileo spacecraft on October 29, 1991 at wavelengths ranging from 0.7 - 5.2 micrometers [Carlson et al., 1992]. This abstract presents a summary of the investigation to identify the material creating the 2.8 micrometer spectral absorption feature. The current best match for the observed 951 Gaspra feature is the phyllosilicate bound hydroxyl signature present in a thermally desiccated QUE 99038 carbonaceous chondrite as measured by Takir et al. [2013].The 951 Gaspra absorption feature has been compared to a variety of hydroxyl bearing signatures. Many phyllosilicates, hydroxyl bearing minerals, have absorption minima at different positions (2.7 or 2.85 micrometers). It also differs from similar absorptions in a potential R chondrite analog, LAP 04840. The spectra LAP 04840 has a 2.7 micrometer feature due to biotite and a 2.9 micrometer feature due to adsorbed water [Klima et al., 2007]. 2.8 micrometer absorption minima have been found for adsorbed hydroxyl on the Moon [McCord et al., 2011] and various carbonaceous chondrites [Calvin and King, 1997; Takir et al., 2013]. The best match, with a minimum Euclidean distance difference to the 951 Gaspra feature, is found in the spectrum of QUE 99038 [Takir et al., 2013]. This spectrum is the product of an infrared measurement of a sample that had its adsorbed water baked off and removed in a vacuum chamber. The remaining hydroxyl in the sample belongs to a mixture of phyllosilicates dominated by the presence of cronstedtite.References: Calvin, W. M., and T. V. King (1997), Met. Planet. Sci., 32, 693-702. Carlson, R. W., et al. (1992), Bull. American Astro. Soc., 24, 932. Granahan, J. C. (2011), Icarus, 213, 265-272. Granahan, J. C. (2014), 45th LPSC, #1092. Klima, R., C. et

  12. Evaluating the Historical Importance of Impact Induced Hydrothermal Systems on Mars Using the Stable Isotopic Composition of Martian Water

    NASA Technical Reports Server (NTRS)

    Niles, Paul B.

    2010-01-01

    The importance of impact events during the early history of Mars is obvious through a simple examination of the character of the martian surface. This ancient, heavily cratered terrain has been shown to be associated with extensive phyllosilicate deposits. This geologic link could suggest that the extensive phyllosilicate-forming alteration may have occurred during early martian history through impact-induced hydrothermal alteration. However, examination of the oxygen isotopic composition of water on Mars suggests that the extensive phyllosilicate deposits were formed primarily through low temperature (<30 C) interactions, and that high temperature weathering in impact-induced hydrothermal systems have not been a dominant process on Mars. The average oxygen isotopic composition of water on Earth is dictated by the nature of water-rock interactions. If these interactions occur at higher temperatures then the water will contain a higher proportion of 18O, while lower temperature interactions will result in water with a lower proportion of 18O. Water on Earth today contains a higher proportion of 18O because of plate tectonics and hydrothermal interaction at mid-ocean ridges. The oxygen isotopic composition of water on early earth, however, may have been quite different, containing a smaller proportion of 18O suggesting much less hydrothermal interaction. Because there are not yet any direct measurements of the oxygen isotopic composition of water on Mars, it needs to be inferred through examination of carbonates preserved in martian meteorites and the isotopic composition of atmospheric CO2. This can be done because the oxygen incorporated into carbonates and CO2 is easily exchanged with liquid water if it is present. Independently, both measurements provide an estimate for the (Sigma)18O of water on Mars to be near -16%. This composition is consistent with low temperature weathering of the silicate crust, and indicates that impact hydrothermal systems did not play

  13. Controllable hydrothermal synthesis of Ni/H-BEA with a hierarchical core-shell structure and highly enhanced biomass hydrodeoxygenation performance.

    PubMed

    Ma, Bing; Cui, Huimei; Wang, Darui; Wu, Peng; Zhao, Chen

    2017-05-11

    Ni based catalysts are wildly used in catalytic industrial processes due to their low costs and high activities. The design of highly hierarchical core-shell structured Ni/HBEA is achieved using a sustainable, simple, and easy-tunable hydrothermal synthesis approach using combined NH 4 Cl and NH 3 ·H 2 O as a co-precipitation agent at 120 °C. Starting from a single-crystalline hierarchical H + -exchanged beta polymorph zeolite (HBEA), the adjustment of the precipitate conditions shows that mixed NH 4 Cl and NH 3 ·H 2 O precipitates with proper concentrations are vital in the hydrothermal synthesis for preserving a good crystalline morphology of HBEA and generating abundant highly-dispersed Ni nanoparticles (loading: 41 wt%, 5.9 ± 0.7 nm) encapsulated onto/into the support. NH 4 Cl solution without an alkali is unable to generate abundant Ni nanoparticles from Ni salts under the hydrothermal conditions, whereas NH 3 ·H 2 O seriously damages the pore structure. After studying the in situ changes in infrared, X-ray diffractometry, temperature-programmed reduction, and scanning electron microscopy measurements, as well as variations in the filtrate pH, Si/Al ratios, and solid sample Ni loading, a two-step dissolution-recrystallization process is proposed. The process consists of Si dissolution and no change in elemental Al, and after the dissolved Si(iv) concentrations have promoted Ni phyllosilicate nanosheet solubility, further growth of multilayered Ni phyllosilicate nanosheets commences. The precursor Ni phyllosilicate is changeable between Ni 3 Si 2 O 5 (OH) 4 and Ni 3 Si 4 O 10 (OH) 2 , because of competition in kinetically-favored and thermodynamically-controlled species caused by different basic agents. The superior catalytic performance is demonstrated in the metal/acid catalyzed biomass derived bulky stearic acid hydrodeoxygenation with 90% octadecane selectivity and a promising rate of 54 g g -1 h -1 , which highly excels the reported rates catalyzed by

  14. Preliminary results on the influence of mineralogy on the turnover rates of SOM from different Hungarian soils

    NASA Astrophysics Data System (ADS)

    Zacháry, Dóra; Szalai, Zoltán; Jakab, Gergely; Németh, Tibor; Sipos, Péter; Filep, Tibor

    2016-04-01

    Fine textured soils generally considered containing more microbial biomass, and having a lower rate of biomass turnover and organic matter decomposition than coarse textured soils. In spite of this, several recent studies have shown contradicting trends. For example, the relative importance of different clay minerals for stabilizing SOM remains an open question. The aim of this study is to evaluate soil mineralological effect on the turnover of SOM by identifying and quantifying soil phyllosilicates. Our samples are derived from C3 forests and C3 croplands from different sites of Hungary. C4 maize residues are added to the soils in order to get natural 13C enrichment as tracer for the young carbon. Bulk samples of the soils from 0 to 20 cm depth were collected. The samples were dried at room temperature and preincubated in the dark for 4 months at 20 °C. The basic soil properties (pH, cation exchange capacity) were analysed after 2 mm sieving and homogenization. The amount of total C and N in the soils and maize residues were analysed using NDIR-chemiluminescent analyzer (Tekmar Dohrman Apollo 9000N). Particle size distribution was determined by laser diffraction (Fritsch Analysette MicroTec 22 plus) and particle imaging method (Malvern Morphologi G3-ID). The mineralological composition of the samples was determined by X-ray diffraction (Philips PW 1730 X-ray diffractometer). Moist soil equivalent to 400 g dry soil mixed with 2 g maize leaves is kept in air tight glass chambers for 183 days at 20°C. The leaves had previously been dried at 60 °C, were cut into pieces and sieved through a 2 mm mesh. The evolved CO2 is trapped by 10 mL 2 M NaOH, which is exchanged on day 1, 3, 5, 7, 10, 14, 21, 28 and subsequently every 31 days. The fractional abundance of 13C of the soils, the plant material and the evolved CO2 is measured with isotope ratio mass spectrometer (Thermo Scientific Delta V IRMS). Our work show the preliminary results on the link between phyllosilicate

  15. Quantitative Zn speciation in a contaminated dredged sediment by μ-PIXE, μ-SXRF, EXAFS spectroscopy and principal component analysis

    NASA Astrophysics Data System (ADS)

    Isaure, Marie-Pierre; Laboudigue, Agnès; Manceau, Alain; Sarret, Géraldine; Tiffreau, Christophe; Trocellier, Patrick; Lamble, Géraldine; Hazemann, Jean-Louis; Chateigner, Daniel

    2002-05-01

    Dredging and disposal of sediments onto agricultural soils is a common practice in industrial and urban areas that can be hazardous to the environment when the sediments contain heavy metals. This chemical hazard can be assessed by evaluating the mobility and speciation of metals after sediment deposition. In this study, the speciation of Zn in the coarse (500 to 2000 μm) and fine (<2 μm) fractions of a contaminated sediment dredged from a ship canal in northern France and deposited on an agricultural soil was determined by physical analytical techniques on raw and chemically treated samples. Zn partitioning between coexisting mineral phases and its chemical associations were first determined by micro-particle-induced X-ray emission and micro-synchrotron-based X-ray radiation fluorescence. Zn-containing mineral species were then identified by X-ray diffraction and powder and polarized extended X-ray absorption fine structure spectroscopy (EXAFS). The number, nature, and proportion of Zn species were obtained by a coupled principal component analysis (PCA) and least squares fitting (LSF) procedure, applied herein for the first time to qualitatively (number and nature of species) and quantitatively (relative proportion of species) speciate a metal in a natural system. The coarse fraction consists of slag grains originating from nearby Zn smelters. In this fraction, Zn is primarily present as sphalerite (ZnS) and to a lesser extent as willemite (Zn 2SiO 4), Zn-containing ferric (oxyhydr)oxides, and zincite (ZnO). In the fine fraction, ZnS and Zn-containing Fe (oxyhydr)oxides are the major forms, and Zn-containing phyllosilicate is the minor species. Weathering of ZnS, Zn 2SiO 4, and ZnO under oxidizing conditions after the sediment disposal accounts for the uptake of Zn by Fe (oxyhydr)oxides and phyllosilicates. Two geochemical processes can explain the retention of Zn by secondary minerals: uptake on preexisting minerals and precipitation with dissolved Fe and Si

  16. Spectral and chemical characterization of jarosite in a palaeolacustrine depositional environment in Warkalli Formation in Kerala, South India and its implications

    NASA Astrophysics Data System (ADS)

    Singh, Mahima; Rajesh, V. J.; Sajinkumar, K. S.; Sajeev, K.; Kumar, S. N.

    2016-11-01

    Coastal cliffs fringing the Arabian Sea near Varkala exhibits the Warkalli Formation of the Tertiary sequence of Kerala, South India, with well-marked occurrence of jarosite associated with other hydrous mineral phases of phyllosilicate family in a palaeo-lacustrine depositional environment. Sandy phyllosilicates dominate the mineral assemblage, but jarosite occurs as a prominent secondary phase formed during acid-sulphate alteration of iron sulphide in this area. Here, we discuss about the potentiality of spectroscopic techniques to identify the possible mineral phases in the collected samples. The samples from the coastal cliffs have been characterized by hyperspectral analysis (VIS-NIR-SWIR), X-ray Diffraction (XRD), Fourier Transform Infra-red Reflectance (FTIR), Electron Probe Microanalysis (EPMA) and Laser Raman spectroscopy. The spectral and chemical analyses have confirmed the jarosite as natrojarosite and phyllosilicate as kaolinite. Other accessory phases have also been identified through XRD. FTIR spectroscopy has played a major role in identifying the major hydrous bonds between the minerals. VIS-NIR-SWIR spectra show several optimum spectral features at 910 nm, 1470 nm, 1849-1864 nm (in the form of a doublet), 1940 nm and 2270 nm, which could be utilised to locate jarosite in the remotely-sensed data. X-ray diffraction peaks helped in the identification of maximum number of minerals (kaolinite, smectite, quartz, feldspar, pyrite, marcasite and hematite) and the variation in jarosite content in the samples. We propose the formation of jarosite in the region by a seasonal, local and temporary development of acidic conditions. Abundance of organic matter in a fluvio-lacustrine environment has developed anaerobic conditions by removing available oxygen through decomposition of organic matter containing sulphur compounds. The sulphur thus liberated combines with hydrogen from water to develop acidic conditions and resulted in the formation of jarosite. The

  17. Characterization of terrestrial hydrothermal alteration products with Mars analog instrumentation: Implications for current and future rover investigations

    NASA Astrophysics Data System (ADS)

    Black, Sarah R.; Hynek, Brian M.

    2018-06-01

    Interpretation of Martian geology relies heavily on our understanding of terrestrial analog deposits and our ability to obtain comprehensive and accurate mineralogical compositions. Many previous studies of terrestrial hydrothermal deposits relied on limited datasets and/or did not use instruments analogous to those deployed on Mars. We analyzed 100 hydrothermally altered basalts from Costa Rica, Nicaragua, and Iceland with Mars analog Visible to Short Wave Infrared (VSWIR) spectroscopy, X-ray Diffraction (XRD), and Raman laser spectrometry. Alteration mineralogy consisted of amorphous and crystalline SiO2 (cristobalite, tridymite, quartz), Ca/Al/Fe/Mg-sulfates (gypsum, anhydrite, alunite, jarosite, hexahydrite, alunogen), Fe-, Ti-, and Mg-oxides/hydroxides (hematite, goethite, anatase/brookite, brucite), elemental sulfur, and phyllosilicates (montmorillonite, kaolinite). Results indicate VSWIR is best suited for identification of X-ray amorphous materials such as hydrated SiO2 and phyllosilicates, while XRD is best utilized for highly ordered crystalline materials such as sulfates, crystalline SiO2 polymorphs, elemental sulfur, and Mg-hydroxides identification. Surprisingly, XRD had the lowest identification rates for Fe-oxides/hydroxides (42% compared to 61% and 75% for VNIR and Raman, respectively), and nearly equal identification rates as VSWIR for kaolinite (76% for VSWIR, 71% for XRD). Identification of phyllosilicates in XRD, while possible, is not as effective as VSWIR without extensive sample preparation. Our observed identification rates may be attributed to the relative abundance of materials-Fe-oxides/hydroxides being present as surface coatings, the presence of large amounts of kaolinite in some samples, and an increased particle size for kaolinite relative to other clays. Elemental sulfur and Fe- and Ti-oxides/hydroxides were more readily identified with Raman. With NASA's current focus on habitability, hydrothermally altered areas-which we know to

  18. Laboratory experiments on ammoniated clay minerals with relevance for asteroid (1) Ceres

    NASA Astrophysics Data System (ADS)

    De Angelis, Simone; Stefani, Stefania; De Sanctis, Maria Cristina; Piccioni, Giuseppe; Ammannito, Eleonora

    2017-04-01

    Recent observations with VIR spectrometer onboard Dawn spacecraft [1] have suggested the presence of ammoniated phyllosilicates widespread on the surface of asteroid (1) Ceres [2,3]. The global surface composition of Ceres as suggested by VIR average infrared spectrum in the 1-4 micron range appears to be due to a mixture of NH4-bearing phyllosilicates, serpentine, carbonates and a dark absorbing phase (magnetite or amorphous carbon) [2]. An absorption feature occurring near 3.1 micron in the average spectrum is considered the main evidence for the presence of NH4-bearing phase; nevertheless in the past several authors tried to explain this feature, as observed with telescopic spectra, invoking the presence of brucite, cronstedtite, water ice or clays [4]. In this project we are carrying out laboratory experiments with the aim of studying ammoniated phyllosilicates in the visible-infrared range. A suite of 9 clay minerals has been used for this study, including illite, nontronite and montmorillonite. In order to produce the ammoniated species we followed a modified procedure based on the one described in Bishop et al. (2002) [5]. All minerals were reduced in fine grain size (<36 micron), treated with ammonium hydroxide (NH4OH) and heated in oven at 200°C for 24 h at normal pressure conditions, before the measurements. Reflectance spectra were acquired with the Fourier Transform Infrared Spectrometer (FTIR) in use at INAF-IAPS/P-LAB, in the range 1-14 μm, on both clay minerals and NH4-treated clays. Almost all spectra of NH4-treated species are characterized by the occurrence of several new absorption features, appearing at different wavelengths near 2, 3, 6 and 7 micron. In some cases the spectral shape of already existent absorption bands resulted deeply modified. A few species did not show the appearance of new features. These results suggest that NH4+ ions fix in various ways in different minerals. Nontronite and montmorillonite appear to be the best

  19. Characterizing Amorphous Silicates in Extraterrestrial Materials

    NASA Astrophysics Data System (ADS)

    Fu, X.; Wang, A.; Krawczynski, M. J.

    2015-12-01

    Amorphous silicates are common in extraterrestrial materials. They are seen in the matrix of carbonaceous chondrites as well as in planetary materials. Tagish Lake is one of the most primitive carbonaceous meteorites in which TEM and XRD analyses found evidence for poorly crystalline phyllosilicate-like species; Raman spectra revealed amorphous silicates with variable degree of polymerization and low crystallinity. On Mars, CheMin discovered amorphous phases in all analyzed samples, and poorly crystalline smectite in mudstone samples. These discoveries pose questions on the crystallinity of phyllosilicates found by remote sensing on Mars, which is directly relevant to aqueous alteration during geologic history of Mars. Our goal is to use spectroscopy to better characterize amorphous silicates. We use three approaches: (1) using silicate glasses synthesized with controlled chemistry to study the effects of silicate polymerization and (2) using phyllosilicates synthesized with controlled hydrothermal treatment to study the effect of crystallinity on vibrational spectroscopy, finally (3) to use the developed correlations in above two steps to study amorphous phases in meteorites, and those found in future missions to Mars. In the 1st step, silicate glasses were synthesized from pure oxides in a range of NBO/T ratios (from 0 to 4). Depending on the targeted NBO/T and composition of mixed oxides, temperatures for each experiment fell in a range from 1260 to 1520 °C, run for ~ 4 hrs. The melt was quenched in liquid N2 or water. Homogeneity of glass was checked under optical microscopy. Raman spectra were taken over 100 spots on small chips free of bubbles and crystals. We have observed that accompanying an increase of NBO/T, there is a strengthening and a position shift of the Raman peak near 1000 cm-1 (Si-Onon-bridging stretching mode), and the weakening of broad Raman peaks near 500 cm-1 (ring breathing mode) and 700cm-1 (Si-Obridging-Si mode). We are building the

  20. Science results from a Mars drilling simulation (Río Tinto, Spain) and ground truth for remote science observations.

    PubMed

    Bonaccorsi, Rosalba; Stoker, Carol R

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. SCIENCE RESULTS: Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (approximately 1:1, approximately 1:2, and approximately 1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (C(org) <0.05 wt %) beneath the biologically active organic-rich soil horizon (C(org) approximately 3-11 wt %) in contrast to the phyllosilicate-rich zones (C(org) approximately 0.23 wt %). GROUND TRUTH VS. REMOTE SCIENCE ANALYSIS: Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5'-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all

  1. Experimental aqueous alteration of the Allende meteorite under oxidizing conditions: Constraints on asteroidal alteration

    NASA Astrophysics Data System (ADS)

    Jones, Catherine L.; Brearley, Adrian J.

    2006-02-01

    assemblage, our experiments most closely resemble alteration in the CI chondrites, although the degree of alteration of our experiments is much lower. CI chondrites contain serpentine/saponite intergrowths and veins of Ca-sulfate and Ca-carbonate as well as the Fe-oxyhydroxide, ferrihydrite. However, the phyllosilicate phases formed in our experiments are somewhat coarser-grained than the finest phyllosilicate fraction present in CI chondrites, suggesting that alteration of the CI chondrites occurred at lower temperatures. In terms of mineral assemblage, our experiments also appear to come close to matching CR chondrites, although we infer that CR alteration probably occurred at temperatures <100 °C, based on the very fine-grained size of phyllosilicates in CR matrices.

  2. Orbital identification of carbonate-bearing rocks on Mars

    Ehlmann, B.L.; Mustard, J.F.; Murchie, S.L.; Poulet, F.; Bishop, J.L.; Brown, A.J.; Calvin, W.M.; Clark, R.N.; Des Marais, D.J.; Milliken, R.E.; Roach, L.H.; Roush, T.L.; Swayze, G.A.; Wray, J.J.

    2008-01-01

    Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region. The carbonate is closely associated with both phyllosilicate-bearing and olivine-rich rock units and probably formed during the Noachian or early Hesperian era from the alteration of olivine by either hydrothermal fluids or near-surface water. The presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering, proposed to be characteristic of Hesperian Mars, did not destroy these carbonates and thus did not dominate all aqueous environments.

  3. Multifunctional Composites for Improved Polyimide Thermal Stability

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.

    2007-01-01

    The layered morphology of silicate clay provides an effective barrier to oxidative degradation of the matrix resin. However, as resin thermal stability continues to reach higher limits, development of an organic modification with comparable temperature capabilities becomes a challenge. Typically, phyllosilicates used in polymer nanocomposites are modified with an alkyl ammonium ion. Such organic modifiers are not suited for incorporation into high temperature polymers as they commonly degrade below 200oC. Therefore, the development of nanoparticle specifically suited for high temperature applications is necessary. Several nanoparticles were investigated in this study, including pre-exfoliated synthetic clay, an organically modified clay, and carbon nanofiber. Dispersion of the layered silicate increases the onset temperature of matrix degradation as well as slows oxidative degradation. The thermally stable carbon nanofibers are also observed to significantly increase the resin thermal stability.

  4. Reaction-induced rheological weakening enables oceanic plate subduction.

    PubMed

    Hirauchi, Ken-Ichi; Fukushima, Kumi; Kido, Masanori; Muto, Jun; Okamoto, Atsushi

    2016-08-26

    Earth is the only terrestrial planet in our solar system where an oceanic plate subducts beneath an overriding plate. Although the initiation of plate subduction requires extremely weak boundaries between strong plates, the way in which oceanic mantle rheologically weakens remains unknown. Here we show that shear-enhanced hydration reactions contribute to the generation and maintenance of weak mantle shear zones at mid-lithospheric depths. High-pressure friction experiments on peridotite gouge reveal that in the presence of hydrothermal water, increasing strain and reactions lead to an order-of-magnitude reduction in strength. The rate of deformation is controlled by pressure-solution-accommodated frictional sliding on weak hydrous phyllosilicate (talc), providing a mechanism for the 'cutoff' of the high peak strength at the brittle-plastic transition. Our findings suggest that infiltration of seawater into transform faults with long lengths and low slip rates is an important controlling factor on the initiation of plate tectonics on terrestrial planets.

  5. The Weathering of Antarctic Meteorites: Climatic Controls on Weathering Rates and Implications for Meteorite Accumulation

    NASA Technical Reports Server (NTRS)

    Benoit, P. H.; Akridge, J. M. C.; Sears, D. W. G.; Bland, P. A.

    1995-01-01

    Weathering of meteorites includes a variety of chemical and mineralogical changes, including conversion of metal to iron oxides, or rust. Other changes include the devitrification of glass, especially in fusion crust. On a longer time scale, major minerals such as olivine, pyroxene, and feldspar are partially or wholly converted to various phyllosilicates. The degree of weathering of meteorite finds is often noted using a qualitative system based on visual inspection of hand specimens. Several quantitative weathering classification systems have been proposed or are currently under development. Wlotzka has proposed a classification system based on mineralogical changes observed in polished sections and Mossbauer properties of meteorite powders have also been used. In the current paper, we discuss induced thermoluminescence (TL) as an indicator of degree of weathering of individual meteorites. The quantitative measures of weathering, including induced TL, suffer from one major flaw, namely that their results only apply to small portions of the meteorite.

  6. Detection Limit of Smectite by Chemin IV Laboratory Instrument: Preliminary Implications for Chemin on the Mars Science Laboratory Mission

    NASA Technical Reports Server (NTRS)

    Archilles, Cherie; Ming, D. W.; Morris, R. V.; Blake, D. F.

    2011-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) is an miniature X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of detecting the mineralogical and elemental compositions of rocks, outcrops and soils on the surface of Mars. CheMin uses a microfocus-source Co X-ray tube, a transmission sample cell, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CRISM and OMEGA have identified the presence of phyllosilicates at several locations on Mars including the four candidate MSL landing sites. The objective of this study was to conduct preliminary studies to determine the CheMin detection limit of smectite in a smectite/olivine mixed mineral system.

  7. Formation of organoclays by a one step synthesis

    NASA Astrophysics Data System (ADS)

    Jaber, Maguy; Miéhé-Brendlé, Jocelyne; Delmotte, Luc; Le Dred, Ronan

    2005-05-01

    Different lamellar hybrid inorganic-organic materials having as inorganic parent 2:1 (T.O.T.) phyllosilicates such as talc, saponite, pyrophyllite, beidellite and montmorillonite were prepared by a one step synthesis. The solids were characterized by X-ray diffraction, solid state 29Si, 27Al, and 19F nuclear magnetic resonance and transmission electron microscopy. XRD patterns show that solids with inorganic parents having octahedral sheet based on aluminium exhibit a lamellar structure similar to MCM-50, whereas those with magnesium have an organophyllosilicate structure. In the first case, the absence of hexacoordinated aluminium was confirmed by 27Al NMR and an ordered stacking of the layers is observed on TEM micrographs. In opposite, a disorder is observed on the TEM images of organophyllosilicates. The formation of the 2:1 structure was found to be controlled mainly by the insertion of silicic species in the interlamellar space of brucite like layers.

  8. The CR (Renazzo-type) carbonaceous chondrite group and its implications

    NASA Technical Reports Server (NTRS)

    Weisberg, Michael K.; Prinz, Martin; Clayton, Robert N.; Mayeda, Toshiko K.

    1993-01-01

    A petrologic, geochemical, and oxygen isotropic study of the CR chondrites including Renazzo, Al Rais, El Djouf 001 and the paired Acfer meteorites, EET87770 and the paired samples, MAC87320, Y790112, Y793495, and Y791498 is presented. It is concluded that the CR group is characterized by abundant large multilayered, Fe, Ni metal-rich, type I chondrules; abundant matrix and dark inclusions; unique assemblages of serpentine and chlorite-rich phyllosilicates and Ca-carbonates; Ca-carbonate rims on chondrules; abundant Fe, Ni metal with a positive Ni vs. Co trend and a solar Ni:Co ratio; and amoeboid olivine aggregates with Mn-rich and Mn-poor forsterite.

  9. The character and evolution of fault rocks from the Phase 3 SAFOD core and potential weakening mechanisms along the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Holdsworth, Robert; van Diggelen, E. W. E.; Spiers, C. J.; de Bresser, H.; Smith, S. A. F.; Bowen, L.

    2010-05-01

    In the region of the SAFOD borehole, the San Andreas Fault (SAF) separates two very different geological terranes referred to here as the Salinian and Great Valley blocks (SB, SVB). Whilst material was not collected from the SB-GVB terrane boundary, the cores preserve a diverse range of fault rocks. Not all of these necessarily formed at the same depth, although the amount of exhumation is likely fairly limited. The distribution of deformation is asymmetric, with a broad (200m wide) intensely deformed region developed in the GVB located NE of the terrane boundary; this includes two narrow zones of active creep that have deformed the borehole casing. Microstructurally, low strain domains (most of Core 1, significant parts of Core 3) preserve clear protolith structures, with highly localised evidence for classic upper crustal cataclastic brittle faulting processes and associated fluid flow. The GVB in particular shows clear geological evidence for both fluid pressure and differential stress cycling (variable modes of hydrofacture associated with faults) during seismicity. There is also evidence in all minor faults for the operation of solution-precipitation creep. High strain domains (much of Core 2, parts of Core 3) are characterised by the development of foliated cataclasites and gouge, with variable new growth of fine-grained, interconnected phyllosilicate networks (predominantly smectite-bearing mixed layer clays). Many of the gouges are characterised by the development of S-C fabrics and asymmetric folds. Reworking and reactivation is widespread manifested by: i) the preservation of one or more earlier generations of gouge preserved as clasts; and ii) by the development of later interconnected, polished and striated slip surfaces at low angles or sub-parallel to the foliation. These are coated with thin smectitic phyllosilicate films and are closely associated with the development of lozenge, arrow-head and triangular mineral veins (mostly calcite) precipitated

  10. The microstructural character and evolution of fault rocks from the SAFOD core and potential weakening mechanisms along the San Andreas Fault (Invited)

    NASA Astrophysics Data System (ADS)

    Holdsworth, R. E.; van Diggelen, E.; Spiers, C.; de Bresser, J. H.; Smith, S. A.

    2009-12-01

    In the region of the SAFOD borehole, the San Andreas Fault (SAF) separates two very different geological terranes referred to here as the Salinian and Great Valley blocks (SB, GVB). The three sections of core preserve a diverse range of fault rocks and pass through the two currently active, highly localised slipping sections, the so-called ‘10480’ and ‘10830’ fault zones . These coincide with a broader region - perhaps as much as 100m wide - of high strain fault rocks formed at some time in the geological past, but now currently inactive. Both the slipping segments and older high strain zone(s) are developed in the GVB located NE of the terrane boundary. This is likely influenced by the phyllosilicate-rich protolith of the GVB and the large volume of trapped fluid known to exist NE and below the SAF in this region. Microstructurally, lower strain domains (most of Core 1 cutting the SB, significant parts of Core 3 cutting the GVB) preserve clear evidence for classic upper crustal cataclastic brittle faulting processes and associated fluid flow. The GVB in particular shows clear geological evidence for both fluid pressure and differential stress cycling (variable modes of hydrofacture associated with faults) during seismicity. There is also some evidence in all minor faults for the operation of limited amounts of solution-precipitation creep. High strain domains (much of Core 2 cutting the GVB, parts of Core 3 adjacent to the 10830 fault) are characterised by the development of foliated cataclasites and gouge largely due to the new growth of fine-grained phyllosilicate networks (predominantly smectite-bearing mixed layer clays, locally serpentinite, but not talc). The most deformed sections are characterised by the development of shear band fabrics and asymmetric folds. Reworking and reactivation is widespread manifested by: i) the preservation of one or more earlier generations of gouge preserved as clasts; and ii) by the development of later interconnected

  11. Moessbauer spectroscopy and scanning electron microscopy of the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Brown, Christopher L.; Oliver, Frederick W.; Hammond, Ernest C., Jr.

    1989-01-01

    Meteorites provide a wealth of information about the solar system's formation, since they have similar building blocks as the Earth's crust but have been virtually unaltered since their formation. Some stony meteorites contain minerals and silicate inclusions, called chondrules, in the matrix. Utilizing Moessbauer spectroscopy, we identified minerals in the Murchison meteorite, a carbonaceous chondritic meteorite, by the gamma ray resonance lines observed. Absorption patterns of the spectra were found due to the minerals olivine and phyllosilicate. We used a scanning electron microscope to describe the structure of the chondrules in the Murchison meteorite. The chondrules were found to be deformed due to weathering of the meteorite. Diameters varied in size from 0.2 to 0.5 mm. Further enhancement of the microscopic imagery using a digital image processor was used to describe the physical characteristics of the inclusions.

  12. A Weathering Index for CK and R Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Huber, Heinz

    2006-01-01

    We present a new weathering index (wi) for the metallic-Fe-Ni-poor chondrite groups (CK and R) based mainly on transmitted light observations of the modal abundance of crystalline material that is stained brown in thin sections: wi-0, <5 vol%; wi-1, 5-25 vol%; wi-2,25-50 vol%; wi-3,50- 75 vol%; wi-4, 75-95 vol%; wi-5, >95 vol%, wi-6, significant replacement of mafic silicates by phyllosilicates. Brown staining reflects mobilization of oxidized iron derived mainly from terrestrial weathering of Ni-bearing sulfide. With increasing degrees of terrestrial weathering of CK and R chondrites, the sulfide modal abundance decreases, and S, Se, and Ni become increasingly depleted. In addition, bulk Cl increases in Antarctic CK chondrites, probably due to contamination from airborne sea mist.

  13. Smectite Formation in Acid Sulfate Environments on Mars

    NASA Technical Reports Server (NTRS)

    Peretyazhko, T. S.; Niles, P. B.; Sutter, B.; Clark, J. V.; Morris, R. V.; Ming, D. W.

    2017-01-01

    Phyllosilicates of the smectite group detected in Noachian and early Hesperian terrains on Mars were hypothesized to form under aqueous conditions that were globally neutral to alkaline. These pH conditions and the presence of a CO2-rich atmosphere should have been favorable for the formation of large carbonate deposits. However, large-scale carbonate deposits have not been detected on Mars. We hypothesized that smectite deposits are consistent with perhaps widespread acidic aqueous conditions that prevented carbonate precipitation. The objective of our work was to investigate smectite formation under acid sulfate conditions in order to provide insight into the possible geochemical conditions required for smectite formation on Mars. Hydrothermal batch incubation experiments were performed with Mars-analogue, glass-rich, basalt simulant in the presence of sulfuric acid of variable concentration.

  14. Computational Study of the Structure of a Sepiolite/Thioindigo Mayan Pigment

    PubMed Central

    Alvarado, Manuel; Chianelli, Russell C.; Arrowood, Roy M.

    2012-01-01

    The interaction of thioindigo and the phyllosilicate clay sepiolite is investigated using density functional theory (DFT) and molecular orbital theory (MO). The best fit to experimental UV/Vis spectra occurs when a single thioindigo molecule attaches via Van der Waals forces to a tetrahedrally coordinated Al3+ cation with an additional nearby tetrahedrally coordinated Al3+ also present. The thioindigo molecule distorts from its planar structure, a behavior consistent with a color change. Due to the weak interaction between thioindigo and sepiolite we conclude that the thioindigo molecule must be trapped in a channel, an observation consistent with previous experimental studies. Future computational studies will look at the interaction of indigo with sepiolite. PMID:23193386

  15. J6 Himalia: New Compositional Evidence and Interpretations for the Origin of Jupiter's Small Satellites

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Jarvis, K.; Larson, S.; Gaffey, M.

    1999-01-01

    New narrowband spectrophotometric data of J6 Himalia, some of which are spatially resolved, support its C-type classification. The new spectra confirm the presence of a weak absorption feature centered near 0.7 micron attributed to oxidized iron in phyllosilicates, products of aqueous alteration, which varies in depth on opposite sides of the satellite. Evaluation of older UBV photometry of J6 and J7 Elara compared to UBV photometry of C-class (and subclass) asteroids showing spectral evidence of the 0.7-microns absorption feature suggests that J6 Himalia is an F-class asteroid. We propose that the parent body of the prograde Jovian satellites originated as part of the Nysa asteroid family. Evolutionary models of the Jovian system are used to address the capture and dispersal of the irregular satellites.

  16. In Situ Detection of Boron by ChemCam on Mars

    NASA Technical Reports Server (NTRS)

    Gasda, Patrick J.; Haldeman, Ethan B.; Wiens, Roger C.; Rapin, William; Bristow, Thomas F.; Bridges, John C.; Schwenzer, Susanne P.; Clark, Benton; Herkenhoff, Kenneth; Frydenvang, Jens; hide

    2017-01-01

    We report the first in situ detection of boron on Mars. Boron has been detected in Gale crater at levels less than 0.05 wt Percent B by the NASA Curiosity rover ChemCam instrument in calcium-sulfate-filled fractures, which formed in a late-stage groundwater circulating mainly in phyllosilicate-rich bedrock interpreted as lacustrine in origin. We consider two main groundwater-driven hypotheses to explain the presence of boron in the veins: leaching of borates out of bedrock or the redistribution of borate by dissolution of borate-bearing evaporite deposits. Our results suggest that an evaporation mechanism is most likely, implying that Gale groundwaters were mildly alkaline. On Earth, boron may be a necessary component for the origin of life; on Mars, its presence suggests that subsurface groundwater conditions could have supported prebiotic chemical reactions if organics were also present and provides additional support for the past habitability of Gale crater.

  17. Mineralogy of Layered Outcrops at Mawrth Vallis and Implications for Early Aqueous Geochemistry on Mars

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Gross, C.; Rampe, E. B.; Wray, J. J.; Parente, M.; Horgan, B.; Loizeau, D.; Viviano-Beck, C. E.; Clark, R. N.; Seelos, F. P.; hide

    2016-01-01

    Recently developed CRISM parameters and newly available DTMs are enabling refined characterization of the mineralogy at Mawrth Vallis. A stratigraphy including 5 units is mapped using HRSC DTMs across 100s of kms and using HiRISE DTMs across 100s of meters. Transitions in mineralogic units were characterized using spectral properties and surface morphology. The observations point to an ancient wet and warm geologic record that formed the thick nontronite unit, a period of wet/dry cycling to create acid alteration, followed by leaching or pedogenesis to result in Al-phyllosilicates, and finally a drier, colder climate that left the altered ash in the form of nanophase aluminosilicates, rather than crystalline clays.

  18. Lunar and Planetary Science XXXV: Origin of Planetary Systems

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session titled Origin of Planetary Systems" included the following reports:Convective Cooling of Protoplanetary Disks and Rapid Giant Planet Formation; When Push Comes to Shove: Gap-opening, Disk Clearing and the In Situ Formation of Giant Planets; Late Injection of Radionuclides into Solar Nebula Analogs in Orion; Growth of Dust Particles and Accumulation of Centimeter-sized Objects in the Vicinity of a Pressure enhanced Region of a Solar Nebula; Fast, Repeatable Clumping of Solid Particles in Microgravity ; Chondrule Formation by Current Sheets in Protoplanetary Disks; Radial Migration of Phyllosilicates in the Solar Nebula; Accretion of the Outer Planets: Oligarchy or Monarchy?; Resonant Capture of Irregular Satellites by a Protoplanet ; On the Final Mass of Giant Planets ; Predicting the Atmospheric Composition of Extrasolar Giant Planets; Overturn of Unstably Stratified Fluids: Implications for the Early Evolution of Planetary Mantles; and The Evolution of an Impact-generated Partially-vaporized Circumplanetary Disk.

  19. Evidence for Impact Shock Melting in CM and CI Chondrite Regolith Samples

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Le, Loan

    2014-01-01

    C class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be near-Earth asteroid 1999 JU3, the target of the Hayabusa II sample return mission [1], although not all spectra indicate this. In fact most spectra of 1999 JU3 are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C class asteroids - impact shock melting. Impact shock melting has been proposed to explain some mineralogical characteristics of CB chondrites, but has not been considered a major process for hydrous carbonaceous chondrites. What evidence is there for significant shock melting in the very abundant CMs, or less abundant but still important CI chondrites?

  20. Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.

    PubMed

    McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A

    2014-01-24

    Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

  1. SciT

    Brown, M. E.; Rhoden, A. R., E-mail: mbrown@caltech.edu, E-mail: Alyssa.Rhoden@jhuapl.edu

    We present a medium resolution spectrum of Jupiter's irregular satellite Himalia covering the critical 3 μm spectral region. The spectrum shows no evidence for aqueously altered phyllosilicates, as had been suggested from the tentative detection of a 0.7 μm absorption, but instead shows a spectrum strikingly similar to the C/CF type asteroid 52 Europa. 52 Europa is the prototype of a class of asteroids generally situated in the outer asteroid belt between less distant asteroids which show evidence for aqueous alteration and more distant asteroids which show evidence for water ice. The spectral match between Himalia and this group of asteroids ismore » surprising and difficult to reconcile with models of the origin of the irregular satellites.« less

  2. Fe-Containing Allophane and Hisingerite Dissolution and Implications for Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Ralston, S. J.; Hausrath, E. M.; Tschauner, O.; Rampe, E. B.; Clark-Hogancamp, J. V.; Christoffersen, R.

    2017-01-01

    The mass-normalized dissolution rates measured in this study demonstrate that hisingerite and Fe-substituted allophane dissolve rapidly, much faster than crystalline phyllosilicates such as nontronite and kaolinite that have similar compositions. In addition, hisingerite dissolves more rapidly than allophane. Future work will focus on measuring dissolution rates at other pH values, so that dissolution rate laws for allophane and hisingerite can be derived. Results will be used to interpret data from Gale Crater. These initial experiments suggest that, if the liquid water present in Gale Crater was highly acidic, it was likely present for only a short time, allowing some amorphous soil-material similar to allophane to persist. Further experiments will enable us to constrain the timescales over which liquid water was present in Gale Crater and provide insight into its pH. This information is essential to assessing the potential habitability of ancient Mars.

  3. Mars Surface Diversity as Revealed by the OMEGA/Mars Express Observations

    NASA Astrophysics Data System (ADS)

    Bibring, Jean-Pierre; Langevin, Yves; Gendrin, Aline; Gondet, Brigitte; Poulet, François; Berthé, Michel; Soufflot, Alain; Arvidson, Ray; Mangold, Nicolas; Mustard, John; Drossart, P.; OMEGA Team; Erard, Stéphane; Forni, Olivier; Combes, Michel; Encrenaz, Thérèse; Fouchet, Thierry; Merchiorri, Riccardo; Belluci, GianCarlo; Altieri, Francesca; Formisano, Vittorio; Bonello, Guillaume; Capaccioni, Fabricio; Cerroni, Pricilla; Coradini, Angioletta; Fonti, Sergio; Kottsov, Volodia; Ignatiev, Nikolai; Moroz, Vassili; Titov, Dimitri; Zasova, Ludmilla; Mangold, Micholas; Pinet, Patrick; Douté, Sylvain; Schmitt, Bernard; Sotin, Christophe; Hauber, Ernst; Hoffmann, Harald; Jaumann, Ralf; Keller, Uwe; Duxbury, Tom; Forget, François

    2005-03-01

    The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) investigation, on board the European Space Agency Mars Express mission, is mapping the surface composition of Mars at a 0.3- to 5-kilometer resolution by means of visible-near-infrared hyperspectral reflectance imagery. The data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy, offering key insights into the evolution of Mars. OMEGA has identified and mapped mafic iron-bearing silicates of both the northern and southern crust, localized concentrations of hydrated phyllosilicates and sulfates but no carbonates, and ices and frosts with a water-ice composition of the north polar perennial cap, as for the south cap, covered by a thin carbon dioxide-ice veneer.

  4. Compositional maps of Saturn's moon Phoebe from imaging spectroscopy

    Clark, R.N.; Brown, R.H.; Jaumann, R.; Cruikshank, D.P.; Nelson, R.M.; Buratti, B.J.; McCord, T.B.; Lunine, J.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Langevin, Y.; Matson, D.L.; Mennella, V.; Nicholson, P.D.; Sicardy, B.; Sotin, Christophe; Hoefen, T.M.; Curchin, J.M.; Hansen, G.; Hibbits, K.; Matz, K.-D.

    2005-01-01

    The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed. Here we report imaging spectroscopy of Phoebe resulting from the Cassini-Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

  5. Petrology of Impact-Melt Rocks at the Chicxulub Multiring Basin, Yucatan, Mexico

    NASA Technical Reports Server (NTRS)

    Schuraytz, Benjamin C.; Sharpton, Virgil L.; Marin, Luis E.

    1994-01-01

    Compositions and textures of melt rocks from the upper part of the Chicxulub structure are typical of melt rocks at other large terrestrial impact structures. Apart from variably elevated iridium concentrations (less than 1.5 to 13.5 +/- 0.9 ppb) indicating nonuniform dissemination of a meteoritic component, bulk rock and phenocryst compositions imply that these melt rocks were derived exclusively from continental crust and platform-sediment target lithologies. Modest differences in bulk chemistry among samples from wells located approximately 40 km apart suggest minor variations in relative contributions of these target lithologies to the melts. Subtle variations in the compositions of early-formed pyroxene and plagioclase also support minor primary differences in chemistry between the melts. Evidence for pervasive hydrothermal alteration of the porous mesostasis includes albite, K-feldspar, quartz, epidote, chlorite, and other phyllosilicates, as well as siderophile element-enriched sulfides, suggesting the possibility that Chicxulub, like Sudbury, may host important ore deposits.

  6. Matrix mineralogy of the Lance CO3 carbonaceous chondrite - A transmission electron microscope study

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Buseck, Peter R.

    1990-01-01

    Results are presented on electron microprobe analyses of three CO chondrites, all of which are falls: Lance, Kainsaz, and Warrenton. The TEM mineralogy results of Lance chondrite show that Fe-rich matrix olivines have been altered to Fe-bearing serpentine and Fe(3+) oxide; matrix metal was also altered to produce Fe(3+) oxides, leaving the residual metal enriched in Ni. Olivine grains in Lance's matrix contain channels along their 100-line and 001-line directions; the formation and convergence of such channels resulted in a grain-size reduction of the olivine. A study of Kainsaz and Warrenton showed that these meteorites do not contain phyllosilicates in their matrices, although both contain Fe(3+) oxide between olivine grains. It is suggested that, prior to its alteration, Lance probably resembled Kainsaz, an unaltered CO3 chondrite.

  7. Confidence Hills Mineralogy and Chemin Results from Base of Mt. Sharp, Pahrump Hills, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Cavanagh, P. D.; Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Morris, R. V.; Ming, D. W.; Rampe, E. B.; Achilles, C. N.; Chipera, S. J.; Treiman, A. H.; hide

    2015-01-01

    The Mars Science Laboratory (MSL) rover Curiosity recently completed its fourth drill sampling of sediments on Mars. The Confidence Hills (CH) sample was drilled from a rock located in the Pahrump Hills region at the base of Mt. Sharp in Gale Crater. The CheMin X-ray diffractometer completed five nights of analysis on the sample, more than previously executed for a drill sample, and the data have been analyzed using Rietveld refinement and full-pattern fitting to determine quantitative mineralogy. Confidence Hills mineralogy has several important characteristics: 1) abundant hematite and lesser magnetite; 2) a 10 angstrom phyllosilicate; 3) multiple feldspars including plagioclase and alkali feldspar; 4) mafic silicates including forsterite, orthopyroxene, and two types of clinopyroxene (Ca-rich and Ca-poor), consistent with a basaltic source; and 5) minor contributions from sulfur-bearing species including jarosite.

  8. Deposition of talc - kerolite-smectite - smectite at seafloor hydrothermal vent fields: Evidence from mineralogical, geochemical and oxygen isotope studies

    Dekov, V.M.; Cuadros, J.; Shanks, Wayne C.; Koski, R.A.

    2008-01-01

    Talc, kerolite-smectite, smectite, chlorite-smectite and chlorite samples from sediments, chimneys and massive sulfides from six seafloor hydrothermal areas have been analyzed for mineralogy, chemistry and oxygen isotopes. Samples are from both peridotite- and basalt-hosted hydrothermal systems, and basaltic systems include sediment-free and sediment-covered sites. Mg-phyllosilicates at seafloor hydrothermal sites have previously been described as talc, stevensite or saponite. In contrast, new data show tri-octahedral Mg-phyllosilicates ranging from pure talc and Fe-rich talc, through kerolite-rich kerolite-smectite to smectite-rich kerolite-smectite and tri-octahedral smectite. The most common occurrence is mixed-layer kerolite-smectite, which shows an almost complete interstratification series with 5 to 85% smectitic layers. The smectite interstratified with kerolite is mostly tri-octahedral. The degree of crystal perfection of the clay sequence decreases generally from talc to kerolite-smectite with lower crystalline perfection as the proportion of smectite layers in kerolite-smectite increases. Our studies do not support any dependence of the precipitated minerals on the type/subtype of hydrothermal system. Oxygen isotope geothermometry demonstrates that talc and kerolite-smectite precipitated in chimneys, massive sulfide mounds, at the sediment surface and in open cracks in the sediment near seafloor are high-temperature (> 250????C) phases that are most probably the result of focused fluid discharge. The other end-member of this tri-octahedral Mg-phyllosilicate sequence, smectite, is a moderate-temperature (200-250????C) phase forming deep within the sediment (??? 0.8??m). Chlorite and chlorite-smectite, which constitute the alteration sediment matrix around the hydrothermal mounds, are lower-temperature (150-200????C) phases produced by diffuse fluid discharge through the sediment around the hydrothermal conduits. In addition to temperature, other two

  9. Mineralogical Changes in a Predominantly Fluviolacustrine Succession at Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Ming, D. W.; Grotzinger. J. P.; Bristow, T. F.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Gellert, R.; Morris, R. V.; Morrison, S. M.

    2017-01-01

    The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to investigate the strata of lower Aeolis Mons (i.e., Mount Sharp) and characterize their depositional and diagenetic environments. Visible/short-wave infrared spectra from orbit of these strata show variations in phyllosilicate, sulfate, and Fe-oxide minerals, suggesting these units record environmental changes that occurred during the early Hesperian. Curiosity has traversed over 15 km and has climbed through Approx. 200 m of stratigraphic section, made up of predominantly fluviolacustrine (i.e., the Bradbury group and the Murray formation) and aeolian (i.e., the Stimson formation) units. Multiple geochemical and mineralogical instruments are onboard Curiosity to study these ancient rocks, including the Chemistry and Mineralogy (CheMin) instrument, which is an X-ray diffractometer (XRD) and X-ray fluorescence spectrometer, and the Alpha Particle X-ray Spectrometer (APXS).

  10. Effect of Silica Particle Size on Texture, Structure, and Catalytic Performance of Cu/SiO2 Catalysts for Glycerol Hydrogenolysis

    NASA Astrophysics Data System (ADS)

    Qi, Ye Tong; Zhe, Chen Hong; Ning, Xiang

    2018-03-01

    The influences of carrier particle sizes of Cu/SiO2 catalysts for hydrogenolysis of glycerol were studied use mono-dispersed silica as models. Catalysts were prepared by precipitation method with the average size of the mono-dispersed silica supports varying of 10, 20, and 90 nm. Characterization of the catalysts show that the physical properties such as pore volume and BET surface area of the catalysts were largely affected by the carrier particle size of silica. However, the copper dispersion of the three samples were similar. XPS patterns show a difference in the chemical states of copper species, small carrier particle size induced formation of copper phyllosilicate, which benefits on the stability of copper species in reaction. The overall activity in the reaction of glycerol hydrogenolysis shows a correlation with the carrier particle size. The small carrier particles prevent the copper species from aggregation thus such catalysts exhibit good catalytic activity and stability.

  11. Nili Fossae in Natural Color and Across the Spectrum

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) took this image of the Nili Fossae region at 0643 UTC (2:43 a.m. EDT) on June 21, 2007, near 21.15 degrees north latitude, 74.24 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point, and is one of several dozen that CRISM has taken to map the minerals at candidate landing sites for the Mars Science Laboratory (MSL) mission, which will launch in 2010.

    The Nili Fossae region is critical to understanding the history of water on Mars and whether water ever formed environments suitable for life, because the region is underlain by a layer of phyllosilicate (clay) minerals. This type of mineralogy formed where water was in contact with Mars' crustal rocks for very long periods, altering the silicates in volcanic rocks. In addition, phyllosilicates can encapsulate and preserve organic chemicals associated with life (if life was present). Its rocky record of an ancient wet environment makes Nili Fossae a top contender among the 30-plus landing sites being considered for MSL, whose objectives include measuring the chemistry preserved in an ancient wet environment.

    This series of four different versions of the same 544-color image illustrates the mineral-mapping capability that comes from moving beyond the wavelength range of the human eye, and into infrared wavelengths where minerals leave distinct 'fingerprints' in reflected sunlight. At upper left, more than three dozen of the distinct wavelengths measured by CRISM were combined to mimic how the human eye would see the image. The subtle shading comes from the Sun's position high in Mars' sky when the image was taken, creating few shadows. The bland, butterscotch color comes from the dust coating nearly all of the Martian surface to some degree. At upper right

  12. Geological controls on soil parent material geochemistry along a northern Manitoba-North Dakota transect

    Klassen, R.A.

    2009-01-01

    As a pilot study for mapping the geochemistry of North American soils, samples were collected along two continental transects extending east–west from Virginia to California, and north–south from northern Manitoba to the US–Mexican border and subjected to geochemical and mineralogical analyses. For the northern Manitoba–North Dakota segment of the north–south transect, X-ray diffraction analysis and bivariate relations indicate that geochemical properties of soil parent materials may be interpreted in terms of minerals derived from Shield and clastic sedimentary bedrock, and carbonate sedimentary bedrock terranes. The elements Cu, Zn, Ni, Cr and Ti occur primarily in silicate minerals decomposed by aqua regia, likely phyllosilicates, that preferentially concentrate in clay-sized fractions; Cr and Ti also occur in minerals decomposed only by stronger acid. Physical glacial processes affecting the distribution and concentration of carbonate minerals are significant controls on the variation of trace metal background concentrations.

  13. Synchrotron-based Infrared Microspectroscopy as a Useful Tool to Study Hydration States of Meteorite Constituents

    NASA Technical Reports Server (NTRS)

    Moroz, L. V.; Schmidt, M.; Schade, U.; Hiroi, T.; Ivanova, M. A.

    2005-01-01

    The meteorites Dho 225 and Dho 735 were recently found in Oman. Studies of their mineralogical and chemical composition suggest that these unusual meteorites are thermally metamorphosed CM2 chondrites [1,2,3]. Similar to Antarctic metamorphosed carbonaceous chondrites, the Dho 225 and Dho 735 are enriched in heavy oxygen compared to normal CMs [1,2]. However, IR studies indicating dehydration of matrix phyllosilicates are needed to confirm that the two new meteorites from Oman are thermally metamorphosed [4]. Synchrotron-based IR microspectroscopy is a new promising technique which allows the acquisition of IR spectra from extremely small samples. Here we demonstrate that this non-destructive technique is a useful tool to study hydration states of carbonaceous chondrites in situ. In addition, we acquired reflectance spectra of bulk powders of the Dho 225 and Dho 735 in the range of 0.3-50 microns.

  14. From bulk soil to intracrystalline investigation of plant-mineral interaction

    NASA Astrophysics Data System (ADS)

    Lemarchand, D.; Voinot, A.; Chabaux, F.; Turpault, M.

    2011-12-01

    clear contribution of vegetation-recycled B to neoformed mineral phases, whereas B in minerals from the brown acidic soil rather indicates predominant mineral dissolution with little or even no B supply from the soil solution. If B isotopes thus proved their sensitivity to the soil forming conditions, a simple isotopic budget also demonstrates that the isotopic signature shown by the vegetation cannot result from fractionation during boron absorption. Analyses of B isotopes within intracrystalline phyllosilicate minerals further identify the interfoliar layers as the major source of B during plant nutrition. Additionally, weathering experiments placing phyllosilicates in contact with various alteration agents (protons, organic acid or siderophore) point to the role of the latters as likely responsible for the boron liberation from the phyllosilicate interfoliar layers. This scenario gives the phyllosilicate interfoliar layers a central function in the plant nutrition in context studied here of soils developed on granitic bedrocks. It also implies a very dynamic system in which plants and minerals can exchange matter over very short periods of time.

  15. In situ detection of boron by ChemCam on Mars

    NASA Astrophysics Data System (ADS)

    Gasda, Patrick J.; Haldeman, Ethan B.; Wiens, Roger C.; Rapin, William; Bristow, Thomas F.; Bridges, John C.; Schwenzer, Susanne P.; Clark, Benton; Herkenhoff, Kenneth; Frydenvang, Jens; Lanza, Nina L.; Maurice, Sylvestre; Clegg, Samuel; Delapp, Dorothea M.; Sanford, Veronica L.; Bodine, Madeleine R.; McInroy, Rhonda

    2017-09-01

    We report the first in situ detection of boron on Mars. Boron has been detected in Gale crater at levels <0.05 wt % B by the NASA Curiosity rover ChemCam instrument in calcium-sulfate-filled fractures, which formed in a late-stage groundwater circulating mainly in phyllosilicate-rich bedrock interpreted as lacustrine in origin. We consider two main groundwater-driven hypotheses to explain the presence of boron in the veins: leaching of borates out of bedrock or the redistribution of borate by dissolution of borate-bearing evaporite deposits. Our results suggest that an evaporation mechanism is most likely, implying that Gale groundwaters were mildly alkaline. On Earth, boron may be a necessary component for the origin of life; on Mars, its presence suggests that subsurface groundwater conditions could have supported prebiotic chemical reactions if organics were also present and provides additional support for the past habitability of Gale crater.

  16. CR chondrites: Shock, aqueous alteration and terrestrial weathering

    NASA Astrophysics Data System (ADS)

    Abreu, N. M.

    2012-12-01

    CR chondrite are a group asteroidal meteorites, whose importance lies in the exotic organic and presolar material [1] found in its most pristine members and in the broad range of alteration features represented in the remaining specimens in this group [2]. This FE-SEM, EMPA, FIB/TEM study takes advantage of the CR's mineralogical diversity to define different trends of secondary alteration, by comparing the CR3s to the Antarctic CRs: MIL 07525, MIL 07513, GRA 06100, LAP 04516, GRO 03116, GRO 95577, and EET 96259. Collisions and subsequent annealing have affected MIL 07513, GRA 06100, and GRO 03116. Shock stages are often assigned based on progressive changes in the textures of olivines and feldspars. However, the large olivines in shocked CRs do not appear to record these process. Opaques, on the other hand, preserve hallmark signatures of impacts, such as crystalline metal/sulfide veins. Opaque nodules in MIL 07513, GRA 06100, GRO 03116 consist of intergrowths of μm-sub μm FeNi-rich metal, kamacite, Fe-sulfides, Fe-oxides, nm-sized metallic Cu and CuFe (~85 wt.% Cu, 14 wt.% Fe ± < 1wt.% Co, Ni, S) alloys. MIL 07525, GRO 03116, EET 96259, LAP 04516, and GRO 95577 show increasing signs of aqueous alteration, such as increasing amounts of ordered phyllosilicates. Although most phyllosilicates are intergrowths of Fe-rich serpentine and saponite, LAP 04516 also contains large (μm-sized), interpenetrating, Fe-rich (cronstedtite-like) phyllosilicates packages with 14Å basal spacings, similar to those observed in CI chondrites by [3]. Heterogeneously interspersed within phyllosilicates are amorphous Fe-rich silicates and small grains (<50nm) of Fe-rich sulfides, partly oxidized sulfides, and in LAP 04516, tochilinite. Tochilinite shows consistent enrichments in Si (~5 wt.%), suggesting that this meteorite has undergone similar pathways of aqueous alteration as CM chondrites [e.g., 4-5]. Despite the myriad of mineralogical changes triggered by secondary and tertiary

  17. Interaction among minerals, organics and water in comets: insights from Antarctic micrometeorites

    NASA Astrophysics Data System (ADS)

    Nagahara, Hiroko; Noguchi, Takaaki; Yabuta, Hikaru; Itoh, Shoichi; Sakamoto, Naoya; Mitsunari, Takuya; Okubo, Aya; Okazaki, Ryuji; Nakamura, Tomoki; Tachibana, Shogo; Terada, Kentaro; Ebihara, Mitsuru; Imae, Naoya; Kimura, Makoto

    2016-04-01

    The evolution and interaction of inorganic materials and organic materials are one of the crucial issues of space science, which is also a main topic of current planetary missions. In order to clarify the early stage of evo-lution of primitive materials in the solar system, we have carried out a comprehensive study on micrometeorites collected from the Antarctica virgin snow with SEM, TEM, Carbon-, N-, and O-XANES, and SIMS. On the basis of observation, we estimate the primary materials and the sequence of aqueous reaction in the inorganic and organic materials. The most primitive materials are GEMS (amorphous silicate with Fe-metal and sulfide), small olivine and low-Ca pyroxene, and pyrrhotite, which are embedded in organic materials. The or-ganic materials are macromolecules being rich in C=O groups with subordinate amount of C≡N and/or C=N-C groups, and they accompany D and 15N enrichments. Due to the heavy hydrogen and nitrogen isotopic composi-tions, the organics are estimated to be originated at very low temperature in the molecular cloud or a prestellar environment, which also generated various organic molecules. The aqueous alteration reaction started at first in organic materials, where N-heterocycle, δD, and δ15N are lost and the organics become aromatic-rich. GEMS altered next, where metallic Fe dissolved into water to form Fe-rich saponite remaining Mg-rich amorphous silicate (Stage I). The aromaticity of the organics increases, and the chemical nature of organics becomes close to insoluble organic materials in primitive chondrites. Then, sulfide in GEMS, small olivine and low-Ca pyroxene grains, and Fe-rich saponite react with water to form Mg-rich saponite and Fe-hydroxide (Stage II). Sulfur may have been incorporated into phyllosilicate and/or organics or flew away. Finally, heterogeneous phyllosilicates at Stage II were homogenized to be Mg-rich saponite with formation of carbonate and loss of organics (Stage III). Carbon to form carbonate were

  18. Four Types of Deposits From Wet Conditions on Early Mars

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Each of these four panels shows a close-up view of a different type of geological deposit formed with the involvement of water, based on observations by NASA's Mars Reconnaissance Orbiter. All four date from the earliest period of Martian history, called the Noachian Period.

    The upper-left panel shows carbonates overlying clays in the Nili Fossae region of Mars. The view combines color-coded information from infrared spectral observations by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) with an underlying black-and-white image from the High Resolution Imaging Science Experiment (HiRISE) camera. Beneath a rough-textured capping rock unit (purple) lie banded olivine-bearing layers (yellow), which in some places have been partially or wholly altered to carbonate (green).

    The upper-right panel shows phyllosilicates and chlorides in the Terra Sirenum region, observed by CRISM and HiRISE. Medium-toned, finely fractured rocks containing chloride salts either underlie higher-standing, light-toned phyllosilicates or fill in low spots between them. Both sit on dark, eroded volcanic material.

    The lower-left panel shows the upper portion of canyon wall in Coprates Chasma, observed by HiRISE and CRISM. The chasm rim cuts across the middle of the image. The wall slopes down to the top of the image and continues outside the region shown, exposing multiple phyllosilicate-bearing layers in a section of rock 7 kilometers (4 miles) thick. Two of the layers shown here are finely fractured aluminum clays that dominate the lower half of the image, underlain by thin beds of iron-magnesium clays at the top of the image. The dark material is a remnant of an overlying layer of basaltic sand that has been partly eroded away by the wind.

    The lower-right panel shows phyllosilicates with vertically layered compositions in Mawrth Vallis, observed by HiRISE (presented in enhanced color) and CRISM. The brown-colored knob in the middle of the scene is a

  19. Rare Potassium-Bearing Mica in Allan Hills 84001: Additional Constraints on Carbonate Formation

    NASA Technical Reports Server (NTRS)

    Brearley, A. J.

    1998-01-01

    There have been presented several intriguing observations suggesting evidence of fossil life in martian orthopyroxenite ALH 84001. These exciting and controversial observations have stimulated extensive debate over the origin and history of ALH 84001, but many issues still remain unresolved. Among the most important is the question of the temperature at which the carbonates, which host the putative microfossils, formed. Oxygen- isotopic data, while showing that the carbonates are generally out of isotopic equilibria with the host rock, cannot constrain their temperature of formation. Both low- and high-temperature scenarios are plausible depending on whether carbonate growth occurred in an open or closed system. Petrographic arguments have generally been used to support a high-temperature origin but these appear to be suspect because they assume equilibrium between carbonate compositions that are not in contact. Some observations appear to be consistent with shock mobilization and growth from immiscible silicate-carbonate melts at high temperatures. Proponents of a low-temperature origin for the carbonates are hampered by the fact that there is currently no evidence of hydrous phases that would indicate low temperatures and the presence of a hydrous fluid during the formation of the carbonates. However, the absence of hydrous phases does not rule out carbonate formation at low temperatures, because the carbonate forming fluids may have been extremely CO2 rich, such that hydrous phases would not have been stabilized. In this study, I have carried out additional Transmission electron microscopy (TEM) studies of ALH-84001 and have found evidence of very rare phyllosilicates, which appear to be convincingly of pre-terrestrial origin. At present these observations are limited to one occurrence: further studies are in progress to determine if the phyllosilicates are more widespread.

  20. Indicators and Methods to Understand Past Environments from ExoMars Rover Drills.

    PubMed

    Kereszturi, A; Bradak, B; Chatzitheodoridis, E; Ujvari, G

    2016-11-01

    Great advances are expected during the analysis of drilled material acquired from 2 m depth by ExoMars rover, supported by the comparison to local context, and the joint use of different instruments. Textural information might be less detailed relatively to what is usually obtained at outcrops during classical geological field work on the Earth, partly because of the lack of optical imaging of the borehole wall and also because the collected samples are crushed. However sub-mm scale layering and some other sedimentary features might be identified in the borehole wall observations, or in the collected sample prior to crushing, and also at nearby outcrops. The candidate landing sites provide different targets and focus for research: Oxia Planum requires analysis of phyllosilicates and OH content, at Mawrth Vallis the layering of various phyllosilicates and the role of shallow-subsurface leaching should be emphasized. At Aram Dorsum the particle size and fluvial sedimentary features will be interesting. Hydrated perchlorates and sulphates are ideal targets possibly at every landing sites because of OH retention, especially if they are mixed with smectites, thus could point to even ancient wet periods. Extensive use of information from the infrared wall scanning will be complemented for geological context by orbital and rover imaging of nearby outcrops. Information from the context is especially useful to infer the possible action of past H 2 O. Separation of the ice and liquid water effects will be supported by cation abundance and sedimentary context. Shape of grains also helps here, and composition of transported grains points to the weathering potential of the environment in general. The work on Mars during the drilling and sample analysis will provide brand new experience and knowledge for future missions.

  1. Anodic activation of iron corrosion in clay media under water-saturated conditions at 90 degrees C: characterization of the corrosion interface.

    PubMed

    Schlegel, Michel L; Bataillon, Christian; Blanc, Cécile; Prêt, Dimitri; Foy, Eddy

    2010-02-15

    To understand the process governing iron corrosion in clay over centuries, the chemical and mineralogical properties of solids formed by free or anodically activated corrosion of iron in water-saturated clay at 90 degrees C over 4 months were probed using microscopic and spectroscopic techniques. Free corrosion led to the formation of an internal discontinuous thin (<3 microm thick) magnetite layer, an external layer of Fe-rich phyllosilicate, and a clay transformation layer containing Ca-doped siderite (Ca(0.2)Fe(0.8)CO(3)). The thickness of corroded iron equaled approximately 5-7 microm, consistent with previous studies. Anodic polarization resulted in unequally distributed corrosion, with some areas corrosion-free and others heavily corroded. Activated corrosion led to the formation of an inner magnetite layer, an intermediate Fe(2)CO(3)(OH)(2) (chukanovite) layer, an outer layer of Fe-rich 7 A-phyllosilicate, and a transformed matrix layer containing siderite (FeCO(3)). The corroded thickness was estimated to 85 microm, less than 30% of the value expected from the supplied anodic charge. The difference was accounted for by reoxidation at the anodically polarized surface of cathodically produced H(2)(g). Thus, free or anodically activated corroding conditions led to structurally similar interfaces, indicating that anodic polarization can be used to probe the long-term corrosion of iron in clay. Finally, corrosion products retained only half of Fe oxidized by anodic activation. Missing Fe probably migrated in the clay, where it could interact with radionuclides released by alteration of nuclear glass.

  2. Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

    SciT

    Siebecker, Matthew G.; Chaney, Rufus L.; Sparks, Donald L.

    2017-07-01

    Serpentine soils have elevated concentrations of trace metals including nickel, cobalt, and chromium compared to non-serpentine soils. Identifying the nickel bearing minerals allows for prediction of potential mobility of nickel. Synchrotron-based techniques can identify the solid-phase chemical forms of nickel with minimal sample treatment. Element concentrations are known to vary among soil particle sizes in serpentine soils. Sonication is a useful method to physically disperse sand, silt and clay particles in soils. Synchrotron-based techniques and sonication were employed to identify nickel species in discrete particle size fractions in several serpentine (ultramafic) topsoils to better understand solid-phase nickel geochemistry. Nickel commonlymore » resided in primary serpentine parent material such as layered-phyllosilicate and chain-inosilicate minerals and was associated with iron oxides. In the clay fractions, nickel was associated with iron oxides and primary serpentine minerals, such as lizardite. Linear combination fitting (LCF) was used to characterize nickel species. Total metal concentration did not correlate with nickel speciation and is not an indicator of the major nickel species in the soil. Differences in soil texture were related to different nickel speciation for several particle size fractionated samples. A discussion on LCF illustrates the importance of choosing standards based not only on statistical methods such as Target Transformation but also on sample mineralogy and particle size. Results from the F-test (Hamilton test), which is an underutilized tool in the literature for LCF in soils, highlight its usefulness to determine the appropriate number of standards to for LCF. EXAFS shell fitting illustrates that destructive interference commonly found for light and heavy elements in layered double hydroxides and in phyllosilicates also can occur in inosilicate minerals, causing similar structural features and leading to false positive

  3. Temperature and rate of dehydration of major constituents of carbonaceous chondrites under vacuum conditions

    NASA Astrophysics Data System (ADS)

    Pohl, Leos; Britt, Daniel

    2017-10-01

    Some sub-types of carbonaceous chondrites contain a significant amount of hydrated minerals which produce specific absorption lines, typically due to the presence of hydroxyls. However, if these asteroids have come close enough to the Sun during their history, the high temperatures might have resulted in mineral decomposition and consequent loss of hydroxyl (or water) molecules in the surface layer and even to certain depths. Determination of the hydration state of phyllosilicates typically found on asteroids as well as the relative quantities of hydrated to desiccated phyllosilicates relies on experimental data - the temperature and rate of dehydration. Both dehydration temperature and rate depend on pressure. The rate also depends on the temperature. Experimentally determined phase curves for serpentine, that show for example decomposition of antigorite to forsterite and enstatite or talc and water, exist for GPa pressure levels. For antigorite, these temperatures span the range 500-750°C for pressures between 0.1 GPa and 8 GPa. However, these data are not suitable for vacuum environment found on asteroids; further, at lower pressures, the available data suggest a monotonically decreasing dehydration temperature with decreasing pressure. Also, the available data suggest dependence of both dehydration temperature and rate on the grain size distribution of the mineral. We have determined the temperature and rate of dehydration of the serpentine polymorphs antigorite, lizardite, cronstedtite, under high vacuum conditions and for various grain size distributions. The grain size distributions have been determined by particle analyzer and each sample source was also analyzed using X-Ray Diffraction.

  4. Indicators and Methods to Understand Past Environments from ExoMars Rover Drills

    NASA Astrophysics Data System (ADS)

    Kereszturi, A.; Bradak, B.; Chatzitheodoridis, E.; Ujvari, G.

    2016-11-01

    Great advances are expected during the analysis of drilled material acquired from 2 m depth by ExoMars rover, supported by the comparison to local context, and the joint use of different instruments. Textural information might be less detailed relatively to what is usually obtained at outcrops during classical geological field work on the Earth, partly because of the lack of optical imaging of the borehole wall and also because the collected samples are crushed. However sub-mm scale layering and some other sedimentary features might be identified in the borehole wall observations, or in the collected sample prior to crushing, and also at nearby outcrops. The candidate landing sites provide different targets and focus for research: Oxia Planum requires analysis of phyllosilicates and OH content, at Mawrth Vallis the layering of various phyllosilicates and the role of shallow-subsurface leaching should be emphasized. At Aram Dorsum the particle size and fluvial sedimentary features will be interesting. Hydrated perchlorates and sulphates are ideal targets possibly at every landing sites because of OH retention, especially if they are mixed with smectites, thus could point to even ancient wet periods. Extensive use of information from the infrared wall scanning will be complemented for geological context by orbital and rover imaging of nearby outcrops. Information from the context is especially useful to infer the possible action of past H2O. Separation of the ice and liquid water effects will be supported by cation abundance and sedimentary context. Shape of grains also helps here, and composition of transported grains points to the weathering potential of the environment in general. The work on Mars during the drilling and sample analysis will provide brand new experience and knowledge for future missions.

  5. Alteration of Basalt and Hyaloclastite in the Project Hotspot MHC-2 Core with Some Comparison to Hyaloclastites of the Hawaii Scientific Drilling Program #2 (HSDP) Core

    NASA Astrophysics Data System (ADS)

    Walton, A. W.; Walker, J. R.

    2015-12-01

    Project Hotspot's 1821m coring operation at Mountain Home Air Force Base, Idaho (MHC), sought to examine interaction of hotspot magmas with continental crust and evaluate geothermal resources. Subsurface temperature increased at a gradient of 76˚/km. Alteration was uniform and not intense over the upper part of the core and at the bottom, but differed markedly in an anomalous zone (AZ) from 1700 to 1800m. The MHC core contains diatomite, basalt lava and minor hyaloclastite. Olivine (Ol) in lavas is more-or-less altered to iddingsite. Plagioclase (Plag) has altered to smectite along cleavage planes and fractures except in the AZ, where it is intensely altered to corrensite. Clinopyroxene (CPX, pinkish in thin section) is little altered, as are apatite and opaque minerals (probably ilmenite with magnetite or pyrite in different samples). Interstitial material is converted to smectite or, in the AZ, to corrensite. Phyllosilicate lines vesicles, and calcite, zeolite and phyllosilicate fill them. Pore-lining phillipsite is common shallow in the core, with vesicle-filling analcime and heulandite at greater depth. A fibrous zeolite, probably stilbite, is also present. Hyaloclasts are altered to concentrically layered masses of smectite. MHC hyaloclastites do not display the microbial traces and palagonite ("gel-palagonite") alteration common in Hawaii Scientific Drilling Project #2 (HSDP) samples. HSDP samples do contain pore-lining phillipsite, but pore fillings are chabazite. Calcite is absent in HSDP hyaloclastites. Neither Ol nor Plag were altered in HSDP hyaloclastites. HSPD glasses are less silicic and Ti-rich than MHC lavas, containing Ol rather than CPX as a dominant mafic. However the differences in alteration of hyaloclastites probably reflect either the fact that the HSDP core was collected at temperatures equivalent to those at the top of the MHC-2 core or HSDP samples were from beds that were in modified marine pore water, rather than continental waters.

  6. VARIABLE CHARGE SOILS: MINERALOGY AND CHEMISTRY

    SciT

    Van Ranst, Eric; Qafoku, Nikolla; Noble, Andrew

    2016-09-19

    Soils rich in particles with amphoteric surface properties in the Oxisols, Ultisols, Alfisols, Spodosols and Andisols orders (1) are considered to be variable charge soils (2) (Table 1). The term “variable charge” is used to describe organic and inorganic soil constituents with reactive surface groups whose charge varies with pH and ionic concentration and composition of the soil solution. Such groups are the surface carboxyl, phenolic and amino functional groups of organic materials in soils, and surface hydroxyl groups of Fe and Al oxides, allophane and imogolite. The hydroxyl surface groups are also present on edges of some phyllosilicate mineralsmore » such as kaolinite, mica, and hydroxyl-interlayered vermiculite. The variable charge is developed on the surface groups as a result of adsorption or desorption of ions that are constituents of the solid phase, i.e., H+, and the adsorption or desorption of solid-unlike ions that are not constituents of the solid phase. Highly weathered soils and subsoils (e.g., Oxisols and some Ultisols, Alfisols and Andisols) may undergo isoelectric weathering and reach a “zero net charge” stage during their development. They usually have a slightly acidic to acidic soil solution pH, which is close to either the point of zero net charge (PZNC) (3) or the point of zero salt effect (PZSE) (3). They are characterized by high abundances of minerals with a point of zero net proton charge (PZNPC) (3) at neutral and slightly basic pHs; the most important being Fe and Al oxides and allophane. Under acidic conditions, the surfaces of these minerals are net positively charged. In contrast, the surfaces of permanent charge phyllosilicates are negatively charged regardless of ambient conditions. Variable charge soils therefore, are heterogeneous charge systems.« less

  7. Petrology and provenance of Upper Cretaceous Sandstone, southern San Rafael Mountains, Santa Barbara County, California

    SciT

    Toyne, C.D.

    1987-05-01

    Petrologic analysis of 24 medium to coarse-grained sandstone samples, collected from a 2950-m submarine fan complex of late Campanian-early Maestrichtian age exposed within Mono Creek Canyon, reveal commonly calcite cemented, poorly sorted, subangular biotic arkoses. Framework averages 86.0%. Matrix - primarily detrital quartz, feldspar, and lithic fragments finer than 0.03 mm and mechanically and chemically altered phyllosilicates and labile aphanites - averages 8.9%. Calcite cement averages 4.2%. Porosity averages 0.9%. Gazzi-Dickinson point counts of 400 framework grains per slide yield modal averages of Q/sub 37.7/ F/sub 49.8/ L/sub 12.5/; Qm/sub 27.4/ F/sub 49.8/ Lt/sub 22.8/; Qm/sub 35.6/ P/sub 43.7/ K/submore » 20.7/; and Qp/sub 49.4/ Lv/sub 22.1/ Ls/sub 28.5/. P/F averages 0.68, Lv/L averages 0.45, Qp/Q averages 0.27, and detrital phyllosilicate, predominantly biotite, averages 5.7% of total framework. Neither primary nor secondary parameters vary systematically with stratigraphic position. Miscellaneous constituents average 1.3% of framework and include epidote, garnet, amphibole, pyroxene, zircon, and tourmaline as well as carbonaceous blebs, opaque minerals, and unidentifiable lithic fragments. Separate analysis of 100 medium sized quartz grains per slide indicates a mean population of 63.0% non-undulatory monocrystalline quartz, 9.1% undulatory monocrystalline quartz, 10.1% polycrystalline quartz of 2 to 3 crystals, and 17.9% polycrystalline quartz composed of more than 3 crystals. Modal data, plotted upon provenance discrimination diagrams, indicate a plutonic provenance transitional between a dissected magmatic arc and uplifted basement terrane. Paleocurrent data, neglecting possible clockwise rotation, indicate sediment transport from the north.« less

  8. The redox state of iron in the matrix of CI, CM and metamorphosed CM chondrites by XANES spectroscopy

    NASA Astrophysics Data System (ADS)

    Beck, P.; De Andrade, V.; Orthous-Daunay, F.-R.; Veronesi, G.; Cotte, M.; Quirico, E.; Schmitt, B.

    2012-12-01

    Carbonaceous chondrites record the action of water at some point of their petrological history. These meteorites are usually connected to low albedo asteroid, which present visible/near-IR absorption explained by iron related absorption within phyllosilicates and oxides. In order to obtain quantitative insight into the mineralogy of iron-bearing phases, we have measured X-ray absorption near-edge spectroscopy at the iron K-edge of matrix from carbonaceous chondrites. This method enables to constrain the redox state and environment of iron in these meteorites. For this study, we selected seven CM chondrites and the CI Orgueil, expected to span a range of aqueous alteration degrees. Our analysis of the pre-edge features show that the redox state of Orgueil (CI) is dominated by octahedral Fe and that the Fe3+/(Fe3++Fe2+) atomic ratio is above 80%. Full-inversion of the spectra suggests that the iron budget is dominated by iron oxides, with additional contributions from phyllosilicate. In the case of the CM, the iron speciation appears different that in the case of Orgueil. Cronstedtite is identified from the inversion of the spectra, and suggested by the presence of significant amount of tetrahedral Fe3+. Within the CM chondrites, a trend of aqueous alteration appears presents, and which is roughly correlated to the scheme defined by Rubin et al. (2007). This trend is characterized by an increase in the amount of iron oxides. Two shock metamorphosed CM are present in our dataset (PCA 91008, WIS 91600). If WIS 91600 does not appear distinguishable, from the CM trend, in the case of PCA 91008, shock metamorphism did impact the pre-edge intensity and an increased amount of anhydrous silicates is found. Although the matrix was dehydrated, significant amount of Fe3+ is still present, providing a memory of the aqueous alteration.

  9. A Search for Variation in the Surface Mineralogical Composition of J VI Himalia

    NASA Astrophysics Data System (ADS)

    Jarvis, K. S.; Vilas, F.; Larson, S. M.; Gaffey, M. J.

    1996-09-01

    Diverse spectral data exist for Jupiter's moon J VI Himalia. The overall spectral shape suggests that it has the same mineralogical composition as a C-class asteroid, lending credibility to the theory that Himalia was a C-class asteroid that formed in or near the main asteroid belt and was ejected and captured into orbit around Jupiter. Using an algorithm developed earlier, ECAS photometry (Tholen and Zellner, 1984) of Himalia taken on one date only have tested positively for the presence of a 0.7- mu m feature attributed to an Fe(2+) -> Fe(3+) charge transfer transition in oxidized iron in phyllosilicates. The presence of this feature was confirmed by narrowband spectrophotometry obtained on one date in April, 1995. Narrowband spectrophotometry of Luu (1991) does not cover the full spectral range defined by the 0.7-mu m absorption feature, but is in good agreement with the ECAS photometry. However, no 3.0-mu m water of hydration absorption feature was observed in IR radiometry (A. S., Rivkin, per. comm.). Correlation between the 0.7-mu m feature and the 3.0-mu m feature has been demonstrated in spectra of low-albedo asteroids, and suggests that it should be present. A rough rotational period for Himalia of 9.2 - 9.8 hrs is known. Himalia could represent the junction of two different compositional units, produced when an impact fragmented Himalia's parent body. The presence of iron-bearing phyllosilicates on part of Himalia's surface supports the hypothesis that Himalia is a captured C-class asteroid. Rotationally-resolved spectra of Himalia could confirm a variation in composition; we have started a program to collect these data.

  10. Magnetic Fabrics of Biotite- and Tourmaline-bearing Granites : The Carnmenellis and Bodmin Plutons (british Cornwall)

    NASA Astrophysics Data System (ADS)

    Nguema, T. Minstsa Mi; Bouchez, J. L.

    In order to extract geological information about the possible emplacement mode of the late-Variscan granite plutons of British Cornwall, detailed petro-structural studies, including magnetic fabric coverages, have been performed in Carnmenellis and Bodmin plutons. The behaviour of these granites is paramagnetic (no magnetite). However, tourmaline is ubiquitous in addition to biotite and iron-bearing muscovite. Since tourmaline has an «inverse» magneto-crystalline intrinsic anisotropy, its magnetic signal perturbates th e easy-to-interpret signal carried by the phyllosilicates. In order to overcome the magnetic signal of tourmaline, most specimens were in-air heated at 650°C during 2 hours. This helped growing magnetite grains out of biotite. These new magnetites, that are demonstrated to be magnetically mimetic with respect to biotite, re-inforce dramatically the magnetic signal of the phyllosilicates. A new structural map of Carnmenellis, obtained from after-heating AMS measurements, is compared with the original one. A dominant NW-SE trend of shallowly plunging lineations is reinforced and is attributed to magma stretch along this direction during pluton emplacement within its overlying country rocks. This agrees with some of Ghosh's field measurements (1934), and with already existing regional reconstructions. In addition, a conspicuous NE-SW lineation trend is revealed, in places where the tourmaline content is possibly the highest, particularly along a NE-SW trending corridor crossing through the pluton at its center. These NE-SW trending domains and lineations are ascribed to late-magmatic tension- gashes along which the magma was flowing and the late, boron-enriched, fluids were collected. The preliminary results obtained from Bodmin (work in progress) will be presented and compared with those of Carnmenellis, and integrated into the regional geology frame of western England.

  11. Investigating the response of biotite to impact metamorphism: Examples from the Steen River impact structure, Canada

    NASA Astrophysics Data System (ADS)

    Walton, E. L.; Sharp, T. G.; Hu, J.; Tschauner, O.

    2018-01-01

    Impact metamorphic effects from quartz and feldspar and to a lesser extent olivine and pyroxene have been studied in detail. Comparatively, studies documenting shock effects in other minerals, such as double chain inosilicates, phyllosilicates, carbonates, and sulfates, are lacking. In this study, we investigate impact metamorphism recorded in crystalline basement rocks from the Steen River impact structure (SRIS), a 25 km diameter complex crater in NW Alberta, Canada. An array of advanced analytical techniques was used to characterize the breakdown of biotite in two distinct settings: along the margins of localized regions of shock melting and within granitic target rocks entrained as clasts in a breccia. In response to elevated temperature gradients along shock vein margins, biotite transformed at high pressure to an almandine-Ca/Fe majorite-rich garnet with a density of 4.2 g cm-3. The shock-produced garnets are poikilitic, with oxide and silicate glass inclusions. Areas interstitial to garnets are vesiculated, in support of models for the formation of shock veins via oscillatory slip, with deformation continuing during pressure release. Biotite within granitic clasts entrained within the hot breccia matrix thermally decomposed at ambient pressure to produce a fine-grained mineral assemblage of orthopyroxene + sanidine + titanomagnetite. These minerals are aligned to the (001) cleavage plane of the original crystal. In this and previous work, the transformation of an inosilicate (pargasite) and a phyllosilicate (biotite) to form garnet, an easily identifiable, robust mineral, has been documented. We contend that in deeply eroded astroblemes, high-pressure minerals that form within or in the environs of shock veins may serve as one of the possibly few surviving indicators of impact metamorphism.

  12. Provenance and accommodation pathways of late Quaternary sediments in the deep-water northern Ionian Basin, southern Italy

    NASA Astrophysics Data System (ADS)

    Perri, Francesco; Critelli, Salvatore; Dominici, Rocco; Muto, Francesco; Tripodi, Vincenzo; Ceramicola, Silvia

    2012-12-01

    The northern Calabria along the southeastern coast of Italy provides a favorable setting in which to study complete transects from continental to deep-marine environments. The present northern Ionian Calabrian Basin is a wedge-top basin within the modern foreland-basin system of southern Italy. The Ionian margin of northern Calabria consists of a moderately developed fluvial systems, the Crati and Neto rivers, and diverse smaller coastal drainages draining both the Calabria continental block (i.e., Sila Massif) and the southern Apennines thrust belt (i.e., Pollino Massif). The main-channel sand of the Crati and Neto rivers is quartzofeldspathic with abundant metamorphic and plutonic lithic fragments (granodiorite, granite, gneiss, phyllite and sedimentary lithic fragments). Sedimentary lithic fragments were derived from Jurassic sedimentary successions of the Longobucco Group. The mud samples contain mostly phyllosilicates, quartz, calcite, feldspars and dolomite. Traces of gypsum are present in some samples. The I-S mixed layers, 10 Å-minerals (illite and micas), chlorite and kaolinite are the most abundant phyllosilicates, whereas smectite and chlorite/smectite mixed layers are in small amounts. The geochemical signatures of the muds reflect a provenance characterized by both felsic and mafic rocks with a significant input from carbonate rocks. Furthermore, the degree of source-area weathering was most probably of low intensity rather than moderately intense because CIA values for the studied mud samples are low. Extrapolation of the mean erosion budget from 1 to 25 Ma suggests that at least 5 to 8 km of crust have been removed from the Calabrian orogenic belt and deposited in the marine basins. The Calabrian microplate played an important role in the dynamic evolution of southern Italian fossil and modern basins, representing the key tectonic element of the entire orogenic belt.

  13. An Amoeboid Olivine Aggregate in LEW 85300

    NASA Technical Reports Server (NTRS)

    Komatsu, M. D.; Yamaguchi, A.; Fagan, T. J.; Zolensky, M. E.; Shiran, N.; Mikouchi, T.

    2016-01-01

    Amoeboid Olivine aggregates (AOAs) are irregularly shaped objects commonly observed in carbonaceous chondrites. Because they are composed of fine-grained olivine and Ca-Al-rich minerals, they are sensitive indicators for nebular process and parent body alteration of their parent bodies. Recently an AOA was found in a carbonaceous clast in polymict eucrite LEW 85300. The bulk major element composition of the clast matrix in LEW 85300 suggests a relation to CM, CO and CV chondrites, whereas bulk clast trace and major element compositions do not match any carbonaceous chondrite, suggesting they have a unique origin. Here we characterize the mineralogy of AOA in LEW 85300 and discuss the origin of the carbonaceous clasts. Results and Discussion: The AOA is located in an impact melt vein. Half of the aggregate shows recrystallization textures (euhedral pyroxene and molten metal/FeS) due to impact melting, but the remaining part preserves the original texture. The AOA is composed of olivine, FeS and Mg,Al-phyllosilicate. Individual olivine grains measure 1-8 microns, with Fe-rich rims, probably due to impact heating. Olivines in the AOA are highly forsteritic (Fo95-99), indicating that the AOA escaped thermal metamorphism [4]. Although no LIME (Low-Fe, Mn-Enriched) olivine is observed, forsterite composition and the coexistence of Mg,Al-phyllosilicate suggest that the AOA is similar to those in the Bali-type oxidized CV (CVoxB) and CR chondrites. However, it should be noted that fayalitic olivine, which commonly occurs in CVoxB AOA, is not observed in this AOA. Also, the smaller grain size (<8 microns) of olivine suggests they may be related to CM or CO chondrites. Therefore, we cannot exclude the possibility that the AOA originated from a unique carbonaceous chondrite.

  14. Spectral reflectance properties of minerals exposed to simulated Mars surface conditions

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Craig, M. A.; Kruzelecky, R. V.; Jamroz, W. R.; Scott, A.; Hawthorne, F. C.; Mertzman, S. A.

    2008-05-01

    A number of mineral species were exposed to martian surface conditions of atmospheric pressure and composition, temperature, and UV light regime, and their evolution was monitored using reflectance spectroscopy. The stabilities for different groups varied widely. Phyllosilicate spectra all showed measurable losses of interlayer H 2O, with some structural groups showing more rapid H 2O loss than others. Loss of OH from the phyllosilicates is not always accompanied by a change in metal-OH overtone absorption bands. OH-bearing sulfates, such as jarosite and alunite, show no measurable change in spectral properties, suggesting that they should be spectrally detectable on Mars on the basis of diagnostic absorption bands in the 0.4-2.5 μm region. Fe 3+- and H 2O-bearing sulfates all showed changes in the appearance and/or reduction in depths of hydroxo-bridged Fe 3+ absorption bands, particularly at 0.43 μm. The spectral changes were often accompanied by visible color changes, suggesting that subsurface sulfates exposed to the martian surface environment may undergo measurable changes in reflectance spectra and color over short periods of time (days to weeks). Organic-bearing geological materials showed no measurable change in C sbnd H related absorption bands, while carbonates and hydroxides also showed no systematic changes in spectral properties. The addition of ultraviolet irradiation did not seem to affect mineral stability or rate of spectral change, with one exception (hexahydrite). In some cases, spectral changes could be related to the formation of specific new phases. The data also suggest that hydrated minerals detected on Mars to date retain their diagnostic spectral properties that allow their unique identification.

  15. Origin and Evolution of the Layered Sulfate-Rich Rocks in Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Arvidson, R. E.

    2007-12-01

    Opportunity rover observations show that Meridiani Planum has extensive exposures of sulfate-rich dirty sandstones partially covered by a mix of wind-blown basaltic sand, dust, and a lag deposit of 1 to 5 mm diameter hematitic concretions. The dirty sandstones are interpreted to have formed in an acid-sulfate evaporative lacustrine system that left behind sulfate-rich muds with a siliciclastic component. Erosion by wind and water produced sandstones that were then cemented and diagenetically altered by rising groundwater. Subsequent wind erosion of these deposits and associated advection of basaltic sand onto the outcrops produced the surfaces encountered during the rover's traverses. On a regional scale these sulfate-rich deposits are up to several kilometers in thickness, extend over several hundred thousand square kilometers, and unconformably overlie the fluvially dissected Noachian cratered terrain. Both OMEGA and CRISM hyperspectral data show clear evidence for the presence of phyllosilicate minerals in the cratered terrains adjacent to the sulfate deposits, but not within the sulfate section proper. The ensemble of evidence indicates a change in Meridiani Planum from fluvial erosion and formation of phyllosilicate minerals to deposition of evaporite deposits associated with an acid-sulfate aqueous system. This change is interpreted to be due to a major climatic shift in which a relatively vigorous hydrologic system with extensive neutral rain and snowfall changed to more arid conditions in which a regional-scale acid sulfate groundwater system emerged in Meridiani Planum with enough of a hydrostatic head to produce and retain 1 to 3 km of sulfate-rich deposits.

  16. A strongly hydrated microclast in the Rumuruti chondrite NWA 6828: Implications for the distribution of hydrous material in the solar system

    NASA Astrophysics Data System (ADS)

    Greshake, Ansgar

    2014-05-01

    Hydrous carbonaceous microclasts are by far the most abundant foreign fragments in stony meteorites and mostly resemble CI1-, CM2-, or CR2-like material. Their occurrence is of great importance for understanding the distribution and migration of water-bearing volatile-rich matter in the solar system. This paper reports the first finding of a strongly hydrated microclast in a Rumuruti chondrite. The R3-6 chondrite Northwest Africa 6828 contains a 420 × 325 μm sized angular foreign fragment exhibiting sharp boundaries to the surrounding R-type matrix. The clast is dominantly composed of magnetite, pyrrhotite, rare Ca-carbonate, and very rare Mg-rich olivine set in an abundant fine-grained phyllosilicate-rich matrix. Phyllosilicates are serpentine and saponite. One region of the clast is dominated by forsteritic olivine (Fa<2) supported by a network of interstitial Ca-carbonate. The clast is crosscut by Ca-carbonate-filled veins and lacks any chondrules, calcium-aluminum-rich inclusions, or their respective pseudomorphs. The hydrous clast contains also a single grain of the very rare phosphide andreyivanovite. Comparison with CI1, CM2, and CR2 chondrites as well as with the ungrouped C2 chondrite Tagish Lake shows no positive match with any of these types of meteorites. The clast may, thus, either represent a fragment of an unsampled lithology of the hydrous carbonaceous chondrite parent asteroids or constitute a sample from an as yet unknown parent body, maybe even a comet. Rumuruti chondrites are a unique group of highly oxidized meteorites that probably accreted at a heliocentric distance >1 AU between the formation regions of ordinary and carbonaceous chondrites. The occurrence of a hydrous microclast in an R chondrite attests to the presence of such material also in this region at least at some point in time and documents the wide distribution of water-bearing (possibly zodiacal cloud) material in the solar system.

  17. New composite spectra of Mars, 0.4-5.7 μm

    Erard, Stephane; Calvin, Wendy M.

    1997-01-01

    About 15 areas were observed in the equatorial regions of Mars by the infrared spectrometers IRS (Mariner 6 and 7) and ISM (Phobos-2). The comparison between the spectra shows a remarkable consistency between two data sets acquired 20 years apart and calibrated independently. This similarity demonstrates the accuracy of ISM calibration above 2 μm, except for a possible stray light contribution above 2.6 μm, on the order of ∼1–2% of the solar flux at 2.7 μm. Most differences in spectral shapes are related to differences in spectral/spatial resolution and viewing geometries. No important variation in surface properties is detected, except for a spot in southern Arabia Terra which has a much deeper hydration feature in IRS spectra; differences in viewing geometries and spatial resolutions do not seem to account for this difference that could result from shifting or dehydration of surface materials. Composite spectra of several types of bright and dark materials are computed by modeling the thermal emission and are completed with telescopic spectra in the visible range. Modeled reflectance in the 3.0–5.7 μm range is consistent with basalts and palagonites. The bright regions and analog palagonite spectra are different from hematite in this range, but resemble several phyllosilicates. We infer that (1) although hematite dominates the spectra in the 0.4- to 2.5-μm range, the silicate-clay host is spectrally active beyond 3 μm and can be identified from this domain; (2) phyllosilicates such as montmorillonite or smectite may be abundant components of the martian soils, although the domain below 3 μm lacks the characteristic features of the most usual terrestrial clay minerals.

  18. Aqueous Alteration on Mars. Chapter 23

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W.; Morris, Richard V.; Clark, Benton C.

    2007-01-01

    Aqueous alteration is the change in composition of a rock, produced in response to interactions with H2O-bearing ices, liquids, and vapors by chemical weathering. A variety of mineralogical and geochemical indicators for aqueous alteration on Mars have been identified by a combination of surface and orbital robotic missions, telescopic observations, characterization of Martian meteorites, and laboratory and terrestrial analog studies. Mineralogical indicators for aqueous alteration include goethite (lander), jarosite (lander), kieserite (orbiter), gypsum (orbiter) and other Fe-, Mg-, and Ca-sulfates (landers), halides (meteorites, lander), phyllosilicates (orbiter, meteorites), hematite and nanophase iron oxides (telescopic, orbiter, lander), and Fe-, Mg-, and Ca-carbonates (meteorites). Geochemical indicators (landers only) for aqueous alteration include Mg-, Ca-, and Fe-sulfates, halides, and secondary aluminosilicates such as smectite. Based upon these indicators, several styles of aqueous alteration have been suggested on Mars. Acid-sulfate weathering (e.g., formation of jarosite, gypsum, hematite, and goethite), may occur during (1) the oxidative weathering of ultramafic igneous rocks containing sulfides, (2) sulfuric acid weathering of basaltic materials, and (3) acid fog (i.e., vapors rich in H2SO4) weathering of basaltic or basaltic-derived materials. Near-neutral or alkaline alteration occurs when solutions with pH near or above 7 move through basaltic materials and form phases such as phyllosilicates and carbonates. Very low water:rock ratios appear to have been prominent at most of the sites visited by landed missions because there is very little alteration (leaching) of the original basaltic composition (i.e., the alteration is isochemical or in a closed hydrologic system). Most of the aqueous alteration appears to have occurred early in the history of the planet (3 to 4.5 billion years ago); however, minor aqueous alteration may be occurring at the

  19. The effect of iron on montmorillonite stability. (I) Background and thermodynamic considerations

    NASA Astrophysics Data System (ADS)

    Wilson, James; Savage, David; Cuadros, Javier; Shibata, Masahiro; Ragnarsdottir, K. Vala

    2006-01-01

    It is envisaged that high-level nuclear waste (HLW) will be disposed of in underground repositories. Many proposed repository designs include steel waste canisters and bentonite backfill. Natural analogues and experimental data indicate that the montmorillonite component of the backfill could react with steel corrosion products to produce non-swelling Fe-rich phyllosilicates such as chamosite, berthierine, or Fe-rich smectite. In K-bearing systems, the alteration of montmorillonite to illite/glauconite could also be envisaged. If montmorillonite were altered to non-swelling minerals, the swelling capacity and self-healing properties of the bentonite backfill could be reduced, thereby diminishing backfill performance. The main aim of this paper was to investigate Fe-rich phyllosilicate mineral stability at the canister-backfill interface using thermodynamic modelling. Estimates of thermodynamic properties were made for Fe-rich clay minerals in order to construct approximate phase-relations for end-member/simplified mineral compositions in logarithmic activity space. Logarithmic activity diagrams (for the system Al 2O 3-FeO-Fe 2O 3-MgO-Na 2O-SiO 2-H 2O) suggest that if pore waters are supersaturated with respect to magnetite in HLW repositories, Fe(II)-rich saponite is the most likely montmorillonite alteration product (if f values are significantly lower than magnetite-hematite equilibrium). Therefore, the alteration of montmorillonite may not be detrimental to nuclear waste repositories that include Fe, as long as the swelling behaviour of the Fe-rich smectite produced is maintained. If f exceeds magnetite-hematite equilibrium, and solutions are saturated with respect to magnetite in HLW repositories, berthierine is likely to be more stable than smectite minerals. The alteration of montmorillonite to berthierine could be detrimental to the performance of HLW repositories.

  20. Mineralogical, geochemical, and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic)

    NASA Astrophysics Data System (ADS)

    Gamboa, Adriana; Montero-Serrano, Jean-Carlos; St-Onge, Guillaume; Rochon, André; Desiage, Pierre-Arnaud

    2017-02-01

    Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr, Zn) indicate that modern sedimentary deposition within the Mackenzie-Beaufort Sea Slope and Amundsen Gulf took place under oxic bottom-water conditions, with more turbulent mixing conditions and thus a well-oxygenated water column prevailing within the Amundsen Gulf. The analytical data obtained, combined with multivariate statistical (notably, principal component and fuzzy c-means clustering analyses) and spatial analyses, allowed the division of the study area into four provinces with distinct sedimentary compositions: (1) the Mackenzie Trough-Canadian Beaufort Shelf with high phyllosilicate-Fe oxide-magnetite and Al-K-Ti-Fe-Cr-V-Zn-P contents; (2) Southwestern Banks Island, characterized by high dolomite-K-feldspar and Ca-Mg-LOI contents; (3) the Central Amundsen Gulf, a transitional zone typified by intermediate phyllosilicate-magnetite-K-feldspar-dolomite and Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-LOI contents; and (4) mud volcanoes on the Canadian Beaufort Shelf distinguished by poorly sorted coarse-silt with high quartz-plagioclase-authigenic carbonate and Si-Zr contents, as well as high magnetic susceptibility. Our results also confirm that the present-day sedimentary dynamics on the Canadian Beaufort Shelf is mainly controlled by sediment supply from the Mackenzie River. Overall, these insights provide a basis for future studies using mineralogical, geochemical, and magnetic signatures of Canadian Arctic sediments in order to reconstruct past variations in sediment inputs and transport pathways related to late Quaternary climate and oceanographic changes.

  1. Impact of Oxidative Dissolution on Black Shale Fracturing: Implication for Shale Fracturing Treatment Design

    NASA Astrophysics Data System (ADS)

    You, L.; Chen, Q.; Kang, Y.; Cheng, Q.; Sheng, J.

    2017-12-01

    Black shales contain a large amount of environment-sensitive compositions, e.g., clay minerals, carbonate, siderite, pyrite, and organic matter. There have been numerous studies on the black shales compositional and pore structure changes caused by oxic environments. However, most of the studies did not focus on their ability to facilitate shale fracturing. To test the redox-sensitive aspects of shale fracturing and its potentially favorable effects on hydraulic fracturing in shale gas reservoirs, the induced microfractures of Longmaxi black shales exposed to deionized water, hydrochloric acid, and hydrogen peroxide at room-temperature for 240 hours were imaged by scanning electron microscopy (SEM) and CT-scanning in this paper. Mineral composition, acoustic emission, swelling, and zeta potential of the untreated and oxidative treatment shale samples were also recorded to decipher the coupled physical and chemical effects of oxidizing environments on shale fracturing processes. Results show that pervasive microfractures (Fig.1) with apertures ranging from tens of nanometers to tens of microns formed in response to oxidative dissolution by hydrogen peroxide, whereas no new microfracture was observed after the exposure to deionized water and hydrochloric acid. The trajectory of these oxidation-induced microfractures was controlled by the distribution of phyllosilicate framework and flaky or stringy organic matter in shale. The experiments reported in this paper indicate that black shales present the least resistance to crack initiation and subcritical slow propagation in hydrogen peroxide, a process we refer to as oxidation-sensitive fracturing, which are closely related to the expansive stress of clay minerals, dissolution of redox-sensitive compositions, destruction of phyllosilicate framework, and the much lower zeta potential of hydrogen peroxide solution-shale system. It could mean that the injection of fracturing water with strong oxidizing aqueous solution may

  2. Basalt Weathering in a Cold and Icy Climate: Three Sisters, Oregon as an Analog for Early Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Horgan, B.; Smith, R. J.; Scudder, N. A.; Rutledge, A. M.; Bamber, E.; Morris, R. V.

    2017-01-01

    There is abundant evidence for liquid water on early Mars, but the debate remains whether early Mars was warm and wet or cold and icy with punctuated periods of melting. To further investigate the hypothesis of a cold and icy early Mars, we collected rocks and sediments from the Collier and Diller glacial valleys in the Three Sisters volcanic complex in Oregon. We analyzed rocks and sediments with X-ray diffraction (XRD), scanning and transmission electron microscopies with energy dispersive spectroscopy (SEM, TEM, EDS), and visible, short-wave infrared (VSWIR) and thermal-IR (TIR) spectroscopies to characterize chemical weathering and sediment transport through the valleys. Here, we focus on the composition and mineralogy of the weathering products and how they compare to those identified on the martian surface. Phyllosilicates (smectite), zeolites, and poorly crystalline phases were discovered in pro- and supra-glacial sediments, whereas Si-rich regelation films were found on hand samples and boulders in the proglacial valleys. Most phyllosilicates and zeolites are likely detrital, originating from hydrothermally altered units on North Sister. TEM-EDS analyses of the <2 um size fraction of glacial flour samples demonstrate a variety of poorly crystalline (i.e., no long-range crystallographic order) phases: iron oxides, devitrified volcanic glass, and Fe-Si-Al phases. The CheMin XRD on the Curiosity rover in Gale crater has identified significant amounts of X-ray amorphous materials in all samples measured to date. The amorphous component is likely a combination of silicates, iron oxides, and sulfates. Although we have not yet observed amorphous sulfate in the samples from Three Sisters, the variety of poorly crystalline weathering products found at this site is consistent with the variable composition of the X-ray amorphous component identified by CheMin. We suggest that these amorphous phases on Mars could have formed in a similarly cold and icy environment.

  3. A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter

    Murchie, S.L.; Mustard, J.F.; Ehlmann, B.L.; Milliken, R.E.; Bishop, J.L.; McKeown, N.K.; Noe Dobrea, E.Z.; Seelos, F.P.; Buczkowski, D.L.; Wiseman, S.M.; Arvidson, R. E.; Wray, J.J.; Swayze, G.; Clark, R.N.; Des Marais, D.J.; McEwen, A.S.; Bibring, J.-P.

    2009-01-01

    Martian aqueous mineral deposits have been examined and characterized using data acquired during Mars Reconnaissance Orbiter's (MRO) primary science phase, including Compact Reconnaissance Imaging Spectrometer for Mars hyperspectral images covering the 0.4-3.9 ??m wavelength range, coordinated with higher-spatial resolution HiRISE and Context Imager images. MRO's new high-resolution measurements, combined with earlier data from Thermal Emission Spectrometer; Thermal Emission Imaging System; and Observatoire pour la Min??ralogie, L'Eau, les Glaces et l'Activiti?? on Mars Express, indicate that aqueous minerals are both diverse and widespread on the Martian surface. The aqueous minerals occur in 9-10 classes of deposits characterized by distinct mineral assemblages, morphologies, and geologic settings. Phyllosilicates occur in several settings: in compositionally layered blankets hundreds of meters thick, superposed on eroded Noachian terrains; in lower layers of intracrater depositional fans; in layers with potential chlorides in sediments on intercrater plains; and as thousands of deep exposures in craters and escarpments. Carbonate-bearing rocks form a thin unit surrounding the Isidis basin. Hydrated silica occurs with hydrated sulfates in thin stratified deposits surrounding Valles Marineris. Hydrated sulfates also occur together with crystalline ferric minerals in thick, layered deposits in Terra Meridiani and in Valles Marineris and together with kaolinite in deposits that partially infill some highland craters. In this paper we describe each of the classes of deposits, review hypotheses for their origins, identify new questions posed by existing measurements, and consider their implications for ancient habitable environments. On the basis of current data, two to five classes of Noachian-aged deposits containing phyllosilicates and carbonates may have formed in aqueous environments with pH and water activities suitable for life. Copyright 2009 by the American

  4. Nickel distribution and isotopic fractionation in a Brazilian lateritic regolith: Coupling Ni isotopes and Ni K-edge XANES

    NASA Astrophysics Data System (ADS)

    Ratié, G.; Garnier, J.; Calmels, D.; Vantelon, D.; Guimarães, E.; Monvoisin, G.; Nouet, J.; Ponzevera, E.; Quantin, C.

    2018-06-01

    Ultramafic (UM) rocks are known to be nickel (Ni) rich and to weather quickly, which makes them a good candidate to look at the Ni isotope systematics during weathering processes at the Earth's surface. The present study aims at identifying the Ni solid speciation and discussing the weathering processes that produce Ni isotope fractionation in two deep laterite profiles under tropical conditions (Barro Alto, Goiás State, Brazil). While phyllosilicates and to a lower extent goethite are the main Ni-bearing phases in the saprolitic part of the profile, iron (Fe) oxides dominate the Ni budget in the lateritic unit. Nickel isotopic composition (δ60Ni values) has been measured in each unit of the regolith, i.e., rock, saprock, saprolite and laterite (n = 52). δ60Ni varies widely within the two laterite profiles, from -0.10 ± 0.05‰ to 1.43 ± 0.05‰, showing that significant Ni isotope fractionation occurs during the weathering of UM rocks. Overall, our results show that during weathering, the solid phase is depleted in heavy Ni isotopes due to the preferential sorption and incorporation of light Ni isotopes into Fe oxides; the same mechanisms likely apply to the incorporation of Ni into phyllosilicates (type 2:1). However, an isotopically heavy Ni pool is observed in the solid phase at the bottom of the saprolitic unit. This feature can be explained by two hypotheses that are not mutually exclusive: (i) a depletion in light Ni isotopes during the first stage of weathering due to the preferential dissolution of light Ni-containing minerals, and (ii) the sorption or incorporation of isotopically heavy Ni carried by percolating waters (groundwater samples have δ60Ni of 2.20 and 2.27‰), that were enriched in heavy Ni isotopes due to successive weathering processes in the overlying soil and laterite units.

  5. Nitrogen Concentrations and Isotopic Compositions of Seafloor-Altered Terrestrial Basaltic Glass: Implications for Astrobiology

    PubMed Central

    Banerjee, N.R.; Izawa, M.R.M.; Kobayashi, K.; Lazzeri, K.; Ranieri, L.A.; Nakamura, E.

    2018-01-01

    Abstract Observed enrichments of N (and the δ15N of this N) in volcanic glasses altered on Earth's modern and ancient seafloor are relevant in considerations of modern global N subduction fluxes and ancient life on Earth, and similarly altered glasses on Mars and other extraterrestrial bodies could serve as valuable tracers of biogeochemical processes. Palagonitized glasses and whole-rock samples of volcanic rocks on the modern seafloor (ODP Site 1256D) contain 3–18 ppm N with δ15Nair values of up to +4.5‰. Variably altered glasses from Mesozoic ophiolites (Troodos, Cyprus; Stonyford volcanics, USA) contain 2–53 ppm N with δ15N of −6.3 to +7‰. All of the more altered glasses have N concentrations higher than those of fresh volcanic glass (for MORB, <2 ppm N), reflecting significant N enrichment, and most of the altered glasses have δ15N considerably higher than that of their unaltered glass equivalents (for MORB, −5 ± 2‰). Circulation of hydrothermal fluids, in part induced by nearby spreading-center magmatism, could have leached NH4+ from sediments then fixed this NH4+ in altering volcanic glasses. Glasses from each site contain possible textural evidence for microbial activity in the form of microtubules, but any role of microbes in producing the N enrichments and elevated δ15N remains uncertain. Petrographic analysis, and imaging and chemical analyses by scanning electron microscopy and scanning transmission electron microscopy, indicate the presence of phyllosilicates (smectite, illite) in both the palagonitized cracks and the microtubules. These phyllosilicates (particularly illite), and possibly also zeolites, are the likely hosts for N in these glasses. Key Words: Nitrogen—Nitrogen isotope—Palagonite—Volcanic glass—Mars. Astrobiology 18, 330–342. PMID:29106312

  6. Flash pyrolysis of adsorbed aromatic organic acids on carbonate minerals: Assessing the impact of mineralogy for the identification of organic compounds in extraterrestrial bodies

    NASA Astrophysics Data System (ADS)

    Zafar, R.

    2017-12-01

    The relationship between minerals and organics is an essential factor in comprehending the origin of life on extraterrestrial bodies. So far organic molecules have been detected on meteorites, comets, interstellar medium and interplanetary dust particles. While on Mars, organic molecules may also be present as indicated by the Sample Analysis at Mars (SAM) instrument suite on the Curiosity Rover in Martian sediments. Minerals including hydrated phyllosilicate, carbonate, and sulfate minerals have been confirmed in carbonaceous chondrites. The presence of phyllosilicate minerals on Mars has been indicated by in situ elemental analysis by the Viking Landers, remote sensing infrared observations and the presence of smectites in meteorites. Likewise, the presence of carbonate minerals on the surface of Mars has been indicated by both Phoenix Lander and Spirit Rover. Considering the fact that both mineral and organic matter are present on the surface of extraterrestrial bodies including Mars, a comprehensive work is required to understand the interaction of minerals with specific organic compounds. The adsorption of the organic molecule at water/mineral surface is a key process of concentrating organic molecules on the surface of minerals. Carboxylic acids are abundantly observed in extraterrestrial material such as meteorites and interstellar space. It is highly suspected that carboxylic acids are also present on Mars due to the average organic carbon infall rate of 108 kg/yr. Further aromatic organic acids have also been observed in carbonaceous chondrite meteorites. This work presents the adsorption of an aromatic carboxylic acid at the water/calcite interface and characterization of the products formed after adsorption via on-line pyrolysis. Adsorption and online pyrolysis results are used to gain insight into adsorbed aromatic organic acid-calcite interaction. Adsorption and online pyrolysis results are related to the interpretation of organic compounds identified

  7. The Influence of Mineral Matrices on the Thermal Behavior of Glycine

    NASA Astrophysics Data System (ADS)

    Dalai, Punam; Pleyer, Hannes Lukas; Strasdeit, Henry; Fox, Stefan

    2017-12-01

    On the Hadean-Early Archean Earth, the first islands must have provided hot and dry environments for abiotically formed organic molecules. The heat sources, mainly volcanism and meteorite impacts, were also available on Mars during the Noachian period. In recent work simulating this scenario, we have shown that neat glycine forms a black, sparingly water-soluble polymer ("thermomelanoid") when dry-heated at 200 °C under pure nitrogen. The present study explores whether relevant minerals and mineral mixtures can change this thermal behavior. Most experiments were conducted at 200 or 250 °C for 2 or 7 days. The mineral matrices used were phyllosilicates (Ca-montmorillonites SAz-1 and STx-1, Na-montmorillonite SAz-1-Na, nontronite NAu-1, kaolinite KGa-1), salts (NaCl, NaCl-KCl, CaCl2, artificial sea salt, gypsum, magnesite), picritic basalt, and three Martian regolith simulants (P-MRS, S-MRS, JSC Mars-1A). The main analytical method employed was high-performance liquid chromatography (HPLC). Glycine intercalated in SAz-1 and SAz-1-Na was well protected against thermomelanoid formation and sublimation at 200 °C: after 2 days, 95 and 79 %, respectively, had either survived unaltered or been transformed into the cyclic dipeptide (DKP) and linear peptides up to Gly6. The glycine survival rate followed the order SAz-1 > SAz-1-Na > STx-1 ≈ NAu-1 > KGa-1. Very good protection was also provided by artificial sea salt (84 % unaltered glycine after 200 °C for 7 days). P-MRS promoted the condensation up to Gly6, consistent with its high phyllosilicate content. The remaining matrices were less effective in preserving glycine as such or as peptides.

  8. SciT

    Wan, Jiamin; Tokunaga, Tetsu K.; Ashby, Paul D.

    Interactions between supercritical (sc) CO 2 and minerals are important when CO 2 is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO 2 alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO 2 on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubationmore » with scCO 2 ), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO 2 uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO 2 partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO 2 to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO 2, can increase CO 2 storage capacity by up to ~30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO 2 uptake constitutes a previously unrecognized potential trapping mechanism.« less

  9. Fe/Mg smectite formation under acidic conditions on early Mars

    NASA Astrophysics Data System (ADS)

    Peretyazhko, T. S.; Sutter, B.; Morris, R. V.; Agresti, D. G.; Le, L.; Ming, D. W.

    2016-01-01

    Phyllosilicates of the smectite group detected in Noachian and early Hesperian terrains on Mars have been hypothesized to form under neutral to alkaline conditions. These pH conditions would also be favorable for formation of widespread carbonate deposits which have not been detected on Mars. We propose that smectite deposits on Mars formed under moderately acidic conditions inhibiting carbonate formation. We report here the first synthesis of Fe/Mg smectite in an acidic hydrothermal system [200 °C, pHRT ∼ 4 (pH measured at room temperature) buffered with acetic acid] from Mars-analogue, glass-rich, basalt simulant with and without aqueous Mg or Fe(II) addition under N2-purged anoxic and ambient oxic redox conditions. Synthesized Fe/Mg smectite was examined by X-ray-diffraction, Mössbauer spectroscopy, visible and near-infrared reflectance spectroscopy, scanning electron microscopy and electron microprobe to characterize mineralogy, morphology and chemical composition. Alteration of the glass phase of basalt simulant resulted in formation of the Fe/Mg smectite mineral saponite with some mineralogical and chemical properties similar to the properties reported for Fe/Mg smectite on Mars. Our experiments are evidence that neutral to alkaline conditions on early Mars are not necessary for Fe/Mg smectite formation as previously inferred. Phyllosilicate minerals could instead have formed under mildly acidic pH conditions. Volcanic SO2 emanation and sulfuric acid formation is proposed as the major source of acidity for the alteration of basaltic materials and subsequent formation of Fe/Mg smectite.

  10. Improvement of nitrogen utilization and soil properties by addition of a mineral soil conditioner: mechanism and performance.

    PubMed

    Yan, Xiaodan; Shi, Lin; Cai, Rumeng

    2018-01-01

    A mineral soil conditioner (MSC) composed of activated potash feldspar, gypsum, and calcium carbonate and containing an amount of available mineral nutrients, is shown to be effective for plant growth and acidic soil amelioration. In this study, a field test was conducted over four rice seasons by examining treatment with control check (CK), MSC, biological active carbon, and lime to investigate the nitrogen-use efficiency and mechanism of soil characteristic variations due to the desilicification and allitization of soil as well as the unrestrained use of nitrogen (N) fertilizer in recent years. Influences of MSC on the xylem sap intensity and mean rice yields were evaluated, and the soil type was also analyzed using the FactSage 6.1 Reaction, phase diagram, and Equilib modules. The results of the field trial showed that MSC application increased the xylem sap intensity and nitrogen export intensity by 37.33-39.85% and 31.40-51.20%, respectively. A significant increase (5.63-15.48%) in mean grain yields was achieved with MSC application over that with biological active carbon and lime application. The effects of MSC had a tendency to increase with time in the field experiment results, and grain yields increased after the initial application. The new formation of clay minerals exhibits a significant influence on [Formula: see text] fixation, especially for 2:1 phyllosilicates with illite, owing to the interlayers of the clay minerals. Our preliminary results showed that kaolinite, the main 1:1 phyllosilicate clay mineral in ferralsol, transformed to illite at room temperature as a consequence of the presence of H 4 SiO 4 and available K + supplied by MSC. This indicated that improving the soil quality combined with reducing N losses from soils is an efficient way to control non-point source pollution from agriculture without the risk of decreased in grain yield.

  11. Refractory inclusions from the ungrouped carbonaceous chondrites MAC 87300 and MAC 88107

    NASA Astrophysics Data System (ADS)

    Russell, Sara S.; Davis, Andrew M.; MacPherson, Glenn J.; Guan, Yunbin; Huss, Gary R.

    2000-09-01

    MAC 87300 and MAC 88107 are two unusual carbonaceous chondrites that are intermediate in chemical composition between the CO3 and CM2 meteorite groups. Calcium-aluminum-rich inclusions (CAIs) from these two meteorites are mostly spinel-pyroxene and melilite-rich (Type A) varieties. Spinel-pyroxene inclusions have either a banded or nodular texture, with aluminous diopside rimming iron-poor spinel. Melilite-rich inclusions (4-42) are irregular in shape and contain minor spinel (FeO <1 wt%), perovskite and, more rarely, hibonite. The CAIs in MAC 88107 and MAC 87300 are similar in primary mineralogy to CAIs from low petrologic grade CO3 meteorites, but differ in that they commonly contain phyllosilicates. The two meteorites also differ somewhat from each other: melilite is more abundant and slightly more aluminum-rich in inclusions from MAC 88107 than in those from MAC 87300, and phyllosilicate is more abundant and magnesium-poor in MAC 87300 CAIs relative to that in MAC 88107. These differences suggest that the two meteorites are not paired. CAI sizes and the abundance of melilite-rich CAIs in MAC 88107 and MAC 87300 suggests a genetic relationship to CO3 meteorites, but the CAIs in both have suffered a greater degree of aqueous alteration than is observed in COs. Al-rich melilite in CAIs from both meteorites generally contains excess 26Mg, presumably from the in situ decay of 26Al. Although well-defined isochrons are not observed, the 26Mg excesses are consistent with initial 26Al/27Al ~3-5 ( 10-5. An unusual hibonite-bearing inclusion is isotopically heterogeneous, with two large and abutting hibonite crystals showing significant differences in their degrees of mass-dependent fractionation of 25Mg/24Mg. The two crystals also show differences in their inferred initial 26Al/27Al, 1 ( 10-5 vs. 3 ( 10-6.

  12. Mesoporous single-crystal ZnO nanobelts: supported preparation and patterning.

    PubMed

    Nasi, Lucia; Calestani, Davide; Fabbri, Filippo; Ferro, Patrizia; Besagni, Tullo; Fedeli, Paolo; Licci, Francesca; Mosca, Roberto

    2013-02-07

    We demonstrate that highly porous ZnO nanobelts can be prepared by thermally decomposing ZnS(en)(0.5) hybrid nanobelts (NBs) synthesized through a solvothermal route using Zn layers deposited on alumina substrates as both the Zn substrate and source. Hybrid decomposition by thermal annealing at 400 °C gives porous ZnS NBs that are transformed by further annealing at 600 °C into wurtzite single crystal ZnO nanobelts with an axial direction of [0001]. The evolution of the morphological and structural transformation ZnS(en)(0.5)→ ZnS → ZnO is investigated at the nanoscale by transmission and scanning electron microscopy analyses. Control of the ZnO NB distributions by patterning the Zn metallization on alumina is achieved as a consequence of the parent hybrid NB patterned growth. The presence of NBs on alumina in a ∼100 μm wide region between Zn stripes allows us to fabricate two contact devices where contact pads are electrically connected through a porous ZnO NB entanglement. Such devices are suitable for employment in photodetectors as well as in gas and humidity sensors.

  13. Free and bound excitons in thin wurtzite GaN layers on sapphire

    NASA Astrophysics Data System (ADS)

    Merz, C.; Kunzer, M.; Kaufmann, U.; Akasaki, I.; Amano, H.

    1996-05-01

    Free and bound excitons have been studied by photoluminescence in thin (0268-1242/11/5/010/img8) wurtzite-undoped GaN, n-type GaN:Si as well as p-type GaN:Mg and GaN:Zn layers grown by metal-organic chemical vapour phase deposition (MOCVD). An accurate value for the free A exciton binding energy and an estimate for the isotropically averaged hole mass of the uppermost 0268-1242/11/5/010/img9 valence band are deduced from the data on undoped samples. The acceptor-doped samples reveal recombination lines which are attributed to excitons bound to 0268-1242/11/5/010/img10 and 0268-1242/11/5/010/img11 respectively. These lines are spectrally clearly separated and the exciton localization energies are in line with Haynes' rule. Whenever a comparison is possible, it is found that the exciton lines in these thin MOCVD layers are ultraviolet-shifted by 20 to 25 meV as compared to quasi-bulk (0268-1242/11/5/010/img12) samples. This effect is interpreted in terms of the compressive hydrostatic stress component which thin GaN layers experience when grown on sapphire with an AlN buffer layer.

  14. X-ray standing wave analysis of nanostructures using partially coherent radiation

    SciT

    Tiwari, M. K., E-mail: mktiwari@rrcat.gov.in; Das, Gangadhar; Bedzyk, M. J.

    2015-09-07

    The effect of longitudinal (or temporal) coherence on total reflection assisted x-ray standing wave (TR-XSW) analysis of nanoscale materials is quantitatively demonstrated by showing how the XSW fringe visibility can be strongly damped by decreasing the spectral resolution of the incident x-ray beam. The correction for nonzero wavelength dispersion (δλ ≠ 0) of the incident x-ray wave field is accounted for in the model computations of TR-XSW assisted angle dependent fluorescence yields of the nanostructure coatings on x-ray mirror surfaces. Given examples include 90 nm diameter Au nanospheres deposited on a Si(100) surface and a 3 nm thick Zn layer trapped on top amore » 100 nm Langmuir-Blodgett film coating on a Au mirror surface. Present method opens up important applications, such as enabling XSW studies of large dimensioned nanostructures using conventional laboratory based partially coherent x-ray sources.« less

  15. Corrosion protective performance of amino trimethylene phosphonic acid-metal complex layers fabricated on the cold-rolled steel substrate via one-step assembly

    NASA Astrophysics Data System (ADS)

    Yan, Ru; He, Wei; Zhai, Tianhua; Ma, Houyi

    2018-06-01

    Seeing that amino trimethylene phosphonic acid (ATMP) possesses very strong complexation ability to metal ions and the phosphonic acid group has good affinity for the oxidized iron surface, herein a simple and rapid film-forming method (one-step assembly method) was developed to construct the ATMP-Zn complex conversion layers (ATMP-Zn layers for short) on the cold-rolled steel (CRS) substrate. Zinc ions were found to participate in the formation process of ATMP-based composite film, which made the Zn-containing ATMP film significantly different in appearance, thickness, microstructure and film-forming mechanisms from the Zn-free ATMP film. There was mainly iron (ш) phosphonate in the Zn-free ATMP film, whereas there were Zn2+-ATMP complex and a certain amount of ZnO in the ATMP-Zn composite film. In addition, electrochemical test results clearly indicate that corrosion resistance of ATMP-Zn composite film was greatly enhanced due to the presence of Zn component. Moreover, the corrosion resistance performance could be controlled by adjusting film-forming time, pH and ATMP concentration in the film-forming solutions. The present study provides a new method for the design and fabrication of high-quality environmentally-friendly conversion layers.

  16. Synthesis and controlled release properties of 2,4-dichlorophenoxy acetate–zinc layered hydroxide nanohybrid

    SciT

    Bashi, Abbas M., E-mail: abbasmatrood@yahoo.com; Hussein, Mohd Zobir; Zainal, Zulkarnain

    2013-07-15

    Direct reaction of ZnO with 2,4-dichlorophenoxyacetic acid (24D) solutions of different concentrations allows obtaining new organic–inorganic nanohybrid materials formed by intercalation of 24D into interlayers of zinc layered hydroxide (ZLH). XRD patterns show a progressive evolution of the structure as 24D concentration increases. The nanohybrid obtained at higher 24D concentration (24D–ZLH(0.4)) reveals a well ordered layered structure with two different basal spacings at 25.2 Å and 24 Å. The FTIR spectrum showing the vibrations bands of the functional groups of 24D and of the ZLH confirms the intercalation. SEM images are in agreement with the structural evolution observed by XRDmore » and reveal the ribbon morphology of the nanohybrids. The release studies of 24D showed a rapid release of 94% for the first 100 min governed by the pseudo-second order kinetic model. - Graphical abstract: The phenomenon indicates that the optical energy gap is enlarged with the increase of molar concentrations in 2,4-dichlorophenoxy acetate anion content into ZnO to create a ZLH–24D nanohybrid. - Highlights: • Nanohybrid was synthesized from 2,4-dichlorophenoxy acetate with-Zinc LHD, using wet chemistry. • Characterized using SEM, TEM, EDX, FTIR, XRD and TGA. • Ribbon-shaped 24D–Zn-layered hydroxide nanoparticles with (003) diffractions of 2.5 nm phase were synthesized.« less

  17. Influences of the Tonga Subduction Zone on seafloor massive sulfide deposits along the Eastern Lau Spreading Center and Valu Fa Ridge

    NASA Astrophysics Data System (ADS)

    Evans, Guy N.; Tivey, Margaret K.; Seewald, Jeffrey S.; Wheat, C. Geoff

    2017-10-01

    This study investigates the morphology, mineralogy, and geochemistry of seafloor massive sulfide (SMS) deposits from six back-arc hydrothermal vent fields along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the context of endmember vent fluid chemistry and proximity to the Tonga Subduction Zone. To complement deposit geochemistry, vent fluid analyses of Cu, Zn, Ba, Pb and H2,(aq) were completed to supplement existing data and enable thermodynamic calculations of mineral saturation states at in situ conditions. Results document southward increases in the abundance of mantle-incompatible elements in hydrothermal fluids (Ba and Pb) and SMS deposits (Ba, Pb, As, and Sb), which is also expressed in the abundance of barite (BaSO4) and galena (PbS) in SMS deposits. These increases correspond to a decrease in distance between the ELSC/VFR and the Tonga Subduction Zone that correlates with a change in crustal lithology from back-arc basin basalt in the north to mixed andesite, rhyolite, and dacite in the south. Barite influences deposit morphology, contributing to the formation of horizontal flanges and squat terraces. Results are also consistent with a regional-scale lowering of hydrothermal reaction zone temperatures from north to south (except at the southernmost Mariner vent field) that leads to lower-temperature, higher-pH vent fluids relative to mid-ocean ridges of similar spreading rates (Mottl et al., 2011). These fluids are Cu- and Zn-poor and the deposits formed from these fluids are Cu-poor but Zn-rich. In contrast, at the Mariner vent field, higher-temperature and lower pH vent fluids are hypothesized to result from higher reaction zone temperatures and the localized addition of acidic magmatic volatiles (Mottl et al., 2011). The Mariner fluids are Cu- and Zn-rich and vent from SMS deposits that are rich in Cu but poor in Zn with moderate amounts of Pb. Thermodynamic calculations indicate that the contrasting metal contents of vent fluids

  18. Mineralogy and the release of trace elements from slag from the Hegeler Zinc smelter, Illinois (USA)

    Piatak, Nadine M.; Seal, Robert R.

    2010-01-01

    Slag from the former Hegeler Zn-smelting facility in Illinois (USA) is mainly composed of spinifex Ca-rich plagioclase, fine-grained dendritic or coarse-grained subhedral to anhedral clinopyroxenes, euhedral to subhedral spinels, spherical blebs of Fe sulfides, silicate glass, and less commonly fayalitic olivine. Mullite and quartz were also identified in one sample as representing remnants of the furnace lining. Secondary phases such as goethite, hematite and gypsum are significant in some samples and reflect surficial weathering of the dump piles or represent byproducts of roasting. A relatively rare Zn-rich material contains anhedral willemite, subhedral gahnite, massive zincite, hardystonite and a Zn sulfate (brianyoungite), among other phases, and likely represents the molten content of the smelting furnace before Zn extraction. The bulk major-element chemistry of most slag samples is dominated by SiO2, Al2O3, Fe2O3 and CaO. The bulk composition of the slag suggests a high viscosity of the melt and the mineralogy suggests a high silica content of the melt. Bulk slag trace-element chemistry shows that the dominant metal is Zn with >28.4 wt.% in the Zn-rich material and between 212 and 14,900 mg/kg in the other slags. The concentrations of other trace elements reach the following: 45 mg/kg As, 1170 mg/kg Ba, 191 mg/kg Cd, 242 mg/kg Co, 103 mg/kg Cr, 6360 mg/kg Cu, 107 mg/kg Ni, and 711 mg/kg Pb.Zinc, as the dominant metal in the slags, is likely the most environmentally significant metal in these samples; Cd, Cu, and Pb are also of concern and their concentrations exceed US Environmental Protection Agency preliminary remediation goals for residential soils. Spinel was found to be the dominant concentrator of Zn for samples containing significant Zn (>1 wt.%); the silicate glass also contained relatively high concentrations of Zn compared to other phases. Zinc partitioned into the silicates and oxides in these samples is generally more resistant to

  19. Metallic elements occurrences within metallic fragments in the municipal waste incineration bottom ash

    NASA Astrophysics Data System (ADS)

    Kowalski, Piotr; Kasina, Monika; Michalik, Marek

    2017-04-01

    Bottom ash (BA) from municipal solid waste incineration (MSWI) is composed of grainy ash material, residual components and metallic fragments (from few µm up to 3-5 cm). Its mineral and chemical composition is related to the composition of the waste stream in the incinerator operational area. Wide use of thermal techniques in management of solid waste makes important the studies on valuable components and their distribution within the material in terms of their further processing. By using various valorization or extraction techniques it is possible to extend the range of its possible further application. To investigate metallic elements distribution within metallic fragments of the MSWI BA material produced in municipal waste incineration plant in Poland were collected in 2015 and 2016. BA and its components were investigated using spectroscopic methods of chemical analysis: ICP-OES, ICP-MS, LECO and EDS (used for microanalysis during SEM observations). BA is a material rich in Si (22.5 wt%), Ca (13.4 wt%), Fe (4 wt%), Al (5.2 wt%) and Na (3.5 wt%), composed of equal part of amorphous (silicate glass dominated) and crystalline phase (rich in silicates, aluminosilicates, oxides of non- and metallic elements and sulphates). The content of metallic elements (Al, Fe, Mg, Ti, Mn, Cr, Ni, Sc, Mo, Cu, Pb, Zn, Sn) is 11.5 wt% with domination of Al (5.2 wt%) and Fe (4 wt%) and elevated values of Mg (1 wt%), Ti (0.54 wt%), Cu (0.26 wt%) and Zn (0.27 wt%) (Kowalski et al., 2016). They were mostly concentrated in the form of metallic fragments, mainly as metallic inclusions in the size of 1-20 µm and separated metallic grains in the size of 50-300 µm. Metallic fragments present in the BA are characterized by their composition heterogeneity and various oxygen content. Fragments are rarely composed of single metallic element and usually in their composition up to few main elements dominated over others. The most common were Fe-, Al- and Zn-rich fragments forming respectively

  20. Zincian dolomite related to supergene alteration in the Iglesias mining district (SW Sardinia)

    NASA Astrophysics Data System (ADS)

    Boni, M.; Mondillo, N.; Balassone, G.; Joachimski, M.; Colella, A.

    2013-01-01

    One of the main effects of supergene alteration of ore-bearing hydrothermal dolomite in areas surrounding secondary zinc orebodies ( Calamine-type nonsulfides) in southwestern Sardinia (Italy) is the formation of a broad halo of Zn dolomite. The characteristics of supergene Zn dolomite have been investigated using scanning electron microscopy and qualitative energy-dispersive X-ray spectroscopy, thermodifferential analysis, and stable isotope geochemistry. The supergene Zn dolomite is characterized by variable amounts of Zn, and low contents of Pb and Cd in the crystal lattice. It is generally depleted in Fe and Mn relative to precursor hydrothermal dolomite ( Dolomia Geodica), which occurs in two phases (stoichiometric dolomite followed by Fe-Mn-Zn-rich dolomite), well distinct in geochemistry. Mg-rich smithsonite is commonly associated to Zn dolomite. Characterization of Zn-bearing dolomite using differential thermal analysis shows a drop in temperature of the first endothermic reaction of dolomite decomposition with increasing Zn contents in dolomite. The supergene Zn dolomites have higher δ18O but lower δ13C values than hydrothermal dolomite. In comparison with smithsonite-hydrozincite, the supergene Zn dolomites have higher δ18O, but comparable δ13C values. Formation of Zn dolomite from meteoric waters is indicated by low δ13C values, suggesting the influence of soil-gas CO2 in near-surface environments. The replacement of the dolomite host by supergene Zn dolomite is interpreted as part of a multistep process, starting with a progressive "zincitization" of the dolomite crystals, followed by a patchy dedolomitization s.s. and potentially concluded by the complete replacement of dolomite by smithsonite.

  1. The impact of rapid economic growth and globalization on zinc nutrition in South Korea.

    PubMed

    Kwun, In-Sook; Do, Mi-Sook; Chung, Hae-Rang; Kim, Yang Ha; Beattie, John H

    2009-08-01

    Zn deficiency may be widespread in Asian countries such as South Korea. However, dietary habits have changed in response to rapid economic growth and globalization. Zn nutrition in South Koreans has therefore been assessed during a period (1969-1998) of unprecedented economic growth. Cross-sectional food consumption data from the Korean National Nutrition Survey Reports (KNNSR) of South Korea at four separate time points (1969, 1978, 1988 and 1998) were used to calculate Zn, Ca and phytate intakes using various food composition tables, databases and literature values. Nutrient values in local foods were cited from their analysed values. Average Zn intake was 5.8, 4.8 and 5.3 mg/d for 1969, 1978 and 1988 respectively, increasing to 7.3 mg/d in 1998 (73 % of the Korean Dietary Reference Intake). The phytate:Zn molar ratio decreased from 21 to 8 during the study period. Dietary Zn depletion due to marked decreases in cereal consumption, particularly barley which has a low Zn bioavailability, was counterbalanced by marked increases in the consumption of meat and fish, which are also Zn-rich foods. Reduced phytate consumption coincident with increased Zn intake suggests that Zn bioavailability also improved, particularly by 1998. Although total Zn intake was not greatly affected over the initial period of economic growth in South Korea (1969-1988), Zn contributions from different food sources changed markedly and both Zn intake and potential bioavailability were improved by 1998. The study may have implications for Zn nutrition in other Asian countries currently experiencing rapid economic growth.

  2. In situ monitoring of corrosion mechanisms and phosphate inhibitor surface deposition during corrosion of zinc-magnesium-aluminium (ZMA) alloys using novel time-lapse microscopy.

    PubMed

    Sullivan, James; Cooze, Nathan; Gallagher, Callum; Lewis, Tom; Prosek, Tomas; Thierry, Dominique

    2015-01-01

    In situ time-lapse optical microscopy was used to examine the microstructural corrosion mechanisms in three zinc-magnesium-aluminium (ZMA) alloy coated steels immersed in 1% NaCl pH 7. Preferential corrosion of MgZn(2) lamellae within the eutectic phases was observed in all the ZMA alloys followed by subsequent dissolution of Zn rich phases. The total extent and rate of corrosion, measured using time-lapse image analysis and scanning vibrating electrode technique (SVET) estimated mass loss, decreased as Mg and Al alloying additions were increased up to a level of 3 wt% Mg and 3.7 wt% Al. This was probably due to the increased presence of MgO and Al(2)O(3) at the alloy surface retarding the kinetics of cathodic oxygen reduction. The addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to 1% NaCl pH 7 had a dramatic influence on the corrosion mechanism for a ZMA with passivation of anodic sites through phosphate precipitation observed using time-lapse image analysis. Intriguing rapid precipitation of filamentous phosphate was also observed and it is postulated that these filaments nucleate and grow due to super saturation effects. Polarisation experiments showed that the addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to the 1% NaCl electrolyte promoted an anodic shift of 50 mV in open circuit potential for the ZMA alloy with a reduction in anodic current of 2.5 orders of magnitude suggesting that it was acting primarily as an anodic inhibitor supporting the inferences from the time-lapse investigations. These phosphate additions resulted in a 98% reduction in estimated mass loss as measured by SVET demonstrating the effectiveness of phosphate inhibitors for this alloy system.

  3. Characterization of aerosols containing Zn, Pb, and Cl from an industrial region of Mexico City.

    PubMed

    Moffet, Ryan C; Desyaterik, Yury; Hopkins, Rebecca J; Tivanski, Alexei V; Gilles, Mary K; Wang, Y; Shutthanandan, V; Molina, Luisa T; Abraham, Rodrigo Gonzalez; Johnson, Kirsten S; Mugica, Violeta; Molina, Mario J; Laskin, Alexander; Prather, Kimberly A

    2008-10-01

    Recent ice core measurements show lead concentrations increasing since 1970, suggesting new nonautomobile-related sources of Pb are becoming important worldwide (1). Developing a full understanding of the major sources of Pb and other metals is critical to controlling these emissions. During the March, 2006 MILAGRO campaign, single particle measurements in Mexico City revealed the frequent appearance of particles internally mixed with Zn, Pb, Cl, and P. Pb concentrations were as high as 1.14 microg/m3 in PM10 and 0.76 microg/m3 in PM2.5. Real time measurements were used to select time periods of interest to perform offline analysis to obtain detailed aerosol speciation. Many Zn-rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2 x 6H2O. The internally mixed Pb-Zn-Cl particles represented as much as 73% of the fine mode particles (by number) in the morning hours between 2-5 am. The Pb-Zn-Cl particles were primarily in the submicrometer size range and typically mixed with elemental carbon suggesting a combustion source. The unique single particle chemical associations measured in this study closely match signatures indicative of waste incineration. Our findings also show these industrial emissions play an important role in heterogeneous processing of NO(y) species. Primary emissions of metal and sodium chloride particles emitted by the same source underwent heterogeneous transformations into nitrate particles as soon as photochemical production of nitric acid began each day at approximately 7 am.

  4. SciT

    Shi, Zhiwei; Walker, Amy V., E-mail: amy.walker@utdallas.edu

    The room temperature atomic layerlike deposition (ALLD) of ZnS on functionalized self-assembled monolayers (SAMs) was investigated, using diethyl zinc (DEZ) and in situ generated H{sub 2}S as reactants. Depositions on SAMs with three different terminal groups, –CH{sub 3,} –OH, and –COOH, were studied. It was found that the reaction of DEZ with the SAM terminal group is critical in determining the film growth rate. Little or no deposition is observed on –CH{sub 3} terminated SAMs because DEZ does not react with the methyl terminal group. ZnS does deposit on both –OH and –COOH terminated SAMs, but the grow rate onmore » –COOH terminated SAMs is ∼10% lower per cycle than on –OH terminated SAMs. DEZ reacts with the hydroxyl group on –OH terminated SAMs, while on –COOH terminated SAMs it reacts with both the hydroxyl and carbonyl bonds of the terminal groups. The carbonyl reaction is found to lead to the formation of ketones rather than deposition of ZnS, lowering the growth rate on –COOH terminated SAMs. SIMS spectra show that both –OH and –COOH terminated SAMs are covered by the deposited ZnS layer after five ALLD cycles. In contrast to ZnO ALLD where the composition of the film differs for the first few layers on –COOH and –OH terminated SAMs, the deposited film composition is the same for both –COOH and –OH terminated SAMs. The deposited film is found to be Zn-rich, suggesting that the reaction of H{sub 2}S with the Zn-surface adduct may be incomplete.« less

  5. Correlation of trap states with negative bias thermal illumination stress stabilities in amorphous In-Ga-Zn-O thin-film transistors studied by photoinduced transient spectroscopy

    NASA Astrophysics Data System (ADS)

    Hayashi, Kazushi; Ochi, Mototaka; Hino, Aya; Tao, Hiroaki; Goto, Hiroshi; Kugimiya, Toshihiro

    2017-03-01

    Negative bias thermal illumination stress (NBTIS) stabilities in amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) were studied by photoinduced transient spectroscopy (PITS). The degradation of TFT performance correlated with trap states in the channel region of a-IGZO TFTs with an etch stop layer (ESL). A prominent peak at approximately 100 K was observed in a-IGZO formed under a partial pressure (p/p) of 4% O2. With increasing O2 p/p, an apparent shoulder of around 230 K appeared in PITS spectra. A higher flow rate of SiH4/N2O for the ESL deposition induced trap states associated with the 230 K peak. The peak at approximately 100 K could originate from the depletion of Zn by preannealing, while the peak at approximately 230 K should be attributed to the oxygen-deficient and/or Zn-rich defects due to the formation of OH in a-IGZO. The trap states in a-IGZO TFTs gave rise to degradation in terms of NBTIS. The threshold voltage shift (ΔV th) was 2.5 V, but it increased with the O2 p/p as well as the flow rate of SiH4/N2O for ESL deposition. The time dependence of ΔV th suggested that hydrogen from the ESL and/or in the a-IGZO thin films was incorporated and modified the trap states in the channel region of the a-IGZO TFTs.

  6. Identification of the typical metal particles among haze, fog, and clear episodes in the Beijing atmosphere.

    PubMed

    Hu, Yunjie; Lin, Jun; Zhang, Suanqin; Kong, Lingdong; Fu, Hongbo; Chen, Jianmin

    2015-04-01

    For a better understanding of metal particle morphology and behaviors in China, atmospheric aerosols were sampled in the summer of 2012 in Beijing. The single-particle analysis shows various metal-bearing speciations, dominated by oxides, sulfates and nitrates. A large fraction of particles is soluble. Sources of Fe-bearing particles are mainly steel industries and oil fuel combustion, whereas Zn- and Pb-bearing particles are primarily contributed by waste incineration, besides industrial combustion. Other trace metal particles play a minor rule, and may come from diverse origins. Mineral dust and anthropogenic source like vehicles and construction activities are of less importance to metal-rich particles. Statistics of 1173 analyzed particles show that Fe-rich particles (48.5%) dominate the metal particles, followed by Zn-rich particles (34.9%) and Pb-rich particles (15.6%). Compared with the abundances among clear, haze and fog conditions, a severe metal pollution is identified in haze and fog episodes. Particle composition and elemental correlation suggest that the haze episodes are affected by the biomass burning in the southern regions, and the fog episodes by the local emission with manifold particle speciation. Our results show the heterogeneous reaction accelerated in the fog and haze episodes indicated by more zinc nitrate or zinc sulfate instead of zinc oxide or carbonate. Such information is useful in improving our knowledge of fine airborne metal particles on their morphology, speciation, and solubility, all of which will help the government introduce certain control to alleviate metal pollution. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Zinc interstitial threshold in Al-doped ZnO film: Effect on microstructure and optoelectronic properties

    NASA Astrophysics Data System (ADS)

    Singh, Chetan C.; Panda, Emila

    2018-04-01

    In order to know the threshold quantity of the zinc interstitials that contributes to an increase in carrier concentration in the Al-doped ZnO (AZO) films and their effect on the overall microstructure and optoelectronic properties of these films, in this work, Zn-rich-AZO and ZnO thin films are fabricated by adding excess zinc (from a zinc metallic target) during their deposition in RF magnetron sputtering and are then investigated using a wide range of experimental techniques. All these films are found to grow in a ZnO hexagonal wurtzite crystal structure with strong (002) orientation of the crystallites, with no indication of Al2O3, metallic Zn, and Al. The excessively introduced zinc in these AZO and/or ZnO films is found to increase the shallow donor level defects (i.e., zinc interstitials and oxygen-related electronic defect states), which is found to significantly increase the carrier concentration in these films. Additionally, aluminum is seen to enhance the creation of these electronic defect states in these films, thereby contributing more to the overall carrier concentration of these films. However, carrier mobility is found to decrease when the carrier concentration values are higher than 4 × 1020 cm-3, because of the electron-electron scattering. Whereas the optical band gap of the ZnO films is found to increase with increasing carrier concentration because of the Burstein-Moss shift, these decrease for the AZO films due to the band gap narrowing effect caused by excess carrier concentration.

  8. Hydrothermal processes in the Edmond deposits, slow- to intermediate-spreading Central Indian Ridge

    NASA Astrophysics Data System (ADS)

    Cao, Hong; Sun, Zhilei; Zhai, Shikui; Cao, Zhimin; Jiang, Xuejun; Huang, Wei; Wang, Libo; Zhang, Xilin; He, Yongjun

    2018-04-01

    The Edmond hydrothermal field, located on the Central Indian Ridge (CIR), has a distinct mineralization history owing to its unique magmatic, tectonic, and alteration processes. Here, we report the detailed mineralogical and geochemical characteristics of hydrothermal metal sulfides recovered from this area. Based on the mineralogical investigations, the Edmond hydrothermal deposits comprise of high-temperature Fe-rich massive sulfides, medium-temperature Zn-rich sulfide chimney and low-temperature Ca-rich sulfate mineral assemblages. According to these compositions, three distinctive mineralization stages have been identified: (1) low-temperature consisting largely of