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  • 1
    Monograph available for loan
    Monograph available for loan
    Cambridge : Cambridge Univ. Pr.
    Associated volumes
    Call number: M 95.0470 ; 11/M 93.0961
    In: Cambridge topics in mineral physics and chemistry
    Type of Medium: Monograph available for loan
    Pages: XXIII, 551 S. : graph. Darst.
    Edition: 2nd ed.
    ISBN: 0521430771
    Series Statement: Cambridge topics in mineral physics and chemistry 5
    Classification: A.3.6.
    Language: English
    Location: Upper compact magazine
    Location: Reading room
    Branch Library: GFZ Library
    Branch Library: GFZ Library
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  • 2
    Publication Date: 2019-01-25
    Description: Altitude-dependent, high radar-reflectivity surfaces on Venus are observed on most mountainous volcanic terranes above a planetary radius of about 6054 km. However, high radar-reflectivity areas also occur at lower altitudes in some impact craters and plain terranes. Pyrite (FeS2) is commonly believed to be responsible for the high radar reflectivities at high elevations on Venus, on account of large dielectric constants measured for sulfide-bearing rocks that were erroneously attributed to pyrite instead of pyrrhotite. Pentlandite-pyrrhotite assemblages may be responsible for high reflectivities associated with impact craters on the Venusian surface, by analogy with Fe-Ni sulfide deposits occurring in terrestrial astroblemes. Mixed-valence Fe(2+)-Fe(3+) silicates, including oxyhornblende, oxybiotite, and ilvaite, may contribute to high radar reflecting surfaces on mountain-tops of Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 233-234
    Format: text
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  • 3
    Publication Date: 2019-01-25
    Description: Salts believed to occur in Martian regolith imply that brines occur on Mars, which may have facilitated the oxidation of dissolved Fe(2+) ions after they were released during chemical weathering of basaltic ferromagnesian silicate and iron sulfide minerals. Calculations show that the rate of oxidation of Fe(2+) ions at -35 C in a 6M chloride-sulfate brine that might exist on Mars is about 10(exp 6) times slower that the oxidation rate of iron in ice-cold terrestrial seawater.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 231-232
    Format: text
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  • 4
    Publication Date: 2013-08-31
    Description: Jarosites, which are present in terrestrial gossans capping oxidized sulfides associated with mafic igneous rocks, may also be present in Martian regolith. Spectral characteristics of jarosites are displayed in remote sensed reflectance spectra of bright regions of Mars surface. The occurrence of jarosite in the regolith would imply that acidic permafrost and sulfide ores exist beneath the surface of Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 176-177
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  • 5
    Publication Date: 2013-08-31
    Description: Large areas of Mars' surface are covered by oxidative weathering products containing ferric and sulfate ions having analogies to terrestrial gossans derived from sulfide mineralization associated with iron-rich basalts. Chemical weathering of such massive and disseminated pyrrhotite-pentlandite assemblages and host basaltic rocks in the Martian environment could have produced metastable gossaniferous phases (limonite containing poorly crystalline hydrated ferric sulfates and oxyhydroxides, clay silicates and opal). Underlying groundwater, now permafrost on Mars, may still be acidic due to incomplete buffering reactions by wall-rock alteration of unfractured host rock. Such acidic solutions stabilize temperature-sensitive complex ions and sols which flocculate to colloidal precipitates at elevated temperatures. Sampling procedures of Martian regolith will need to be designed bearing in mind that the frozen permafrost may be corrosive and be stabilizing unique complex ions and sols of Fe, Al, Mg, Ni and other minor elements.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Workshop on Mars Sample Return Science; p 46-47
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  • 6
    Publication Date: 2013-08-31
    Description: Paragenetic evidence that indicates that hisingerite may have formed during the evolution of Martian regolith is summarized. Hisingerite was once regarded as poorly crystalline iron-rich smectite or nontronite. However, recent electron microscopy and X-ray studies have revealed hisingerite to have an amorphous or gel structure containing a disordered array of (FeO6) octahedra and (SiO4) tetrahedra. It is just this coordination environment and degree of crystallinity that matches materials simulating the spectral properties of the bright regions of Mars. Therefore, hisingerite and basic ferric sulfate minerals appear to be major contributers to remote sensed reflectance spectral profiles of Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 175
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  • 7
    Publication Date: 2013-08-31
    Description: In previous Mossbauer spectral studies of many of the Shergotite Nakhlite Chassignite (SNC) meteorites, attention was drawn to the close similarities of spectrum profiles between Lafayette and Nakhla, which were once suggested to be identical meteorites. These observations led to the acquisition of Governador Valadares and another specimen of Nakhla, as well as Zagami and Shergotty, for Mossbauer spectral measurements at 4.2K. Results reported here demonstrate that there are subtle differences between the three nakhlites (Nakhla, Lafayette, and Governador Valadares), as there are for three of the shergottites (Shergotty, Zagami, EETA 79001/lithologies A and B) and olivine-dominated Chassigny and ALHA 77005, indicating that all eight of the SNC meteorites discovered to data fell independently to Earth.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 259-261
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  • 8
    Publication Date: 2013-08-31
    Description: Pyrrhotite-pentlandite assemblages in mafic and ultramafic igneous rocks may have contributed significantly to the chemical weathering reactions that produced degradation products in the Martian regolith. By analogy with terrestrial processes, a model is proposed whereby supergene alteration of these primary Fe-Ni sulfides on Mars has generated secondary sulfides (e.g., pyrite) below the water table and produced acidic groundwater containing high concentrations of dissolved Fe, Ni and sulfate ions. The low pH solutions also initiated weathering reactions of igneous feldspars and ferromagnesian silicates to form clay silicate and ferric oxyhydroxide phases. Near-surface oxidation and hydrolysis of ferric sulfato- and hydroxo-complex ions and sols formed gossans above the water table consisting of poorly crystalline hydrated ferric sulfates (e.g., jarosite), oxides (ferrihydrite, goethite) and silica (opal). Underlying groundwater, now permafrost, contains hydroxo sulfato complexes of Fe, Al, Mg, Ni, etc., which may be stabilized in frozen acidic solutions beneath the surface of Mars. Sublimation of permafrost may replenish colloidal ferric oxides, sulfates and phyllosilicates during dust storms on Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Workshop on Mars Sample Return Science; p 48-50
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  • 9
    Publication Date: 2013-08-31
    Description: The occurrence of ferric bearing assemblages, comprising phyllosilicates, oxide hydroxides and magnetite, in carbonaceous chondrites (CC) indicates that these meteorites underwent pre-terrestrial, sub-aqueous oxidation reactions. Reported here are results of a Mossbauer spectral study of a suite of CC demonstrating that a variety of ferrous and ferric bearing phases may be distinguished in different classes of this meteorite type.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 256-258
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  • 10
    Publication Date: 2013-08-31
    Description: The reflectance spectra of Fe(2+)-Mg(2+) disordered orthopyroxenes are relevant to surfaces of terrestrial planets onto which basaltic magma has been extruded. If cooling rates of basalt lava flows were fast, equilibrium iron intersite partitioning may not have been achieved so that abnormal enrichments of Fe(2+) ions in M1 sites would occur. The two intense pyroxene Fe(2+) site CF bands in the 1 micron and 2 micron regions would continue to dominate the the reflectance spectra so that the pyroxene composition and structure type would be readily identified in telescopic spectral profiles. However, abnormal intensification of the Fe(2+)/M1 site CF band at 1.20 microns could lead to the false identification of olivine in remote sensed spectra because in pyroxene-olivine mixtures the inflection around 1.20 microns is the only spectral feature for detecting the presence of olivine. The identification of iron-bearing plagioclase feldspars, too, would be obscured by the pyroxene Fe(2+)/M1 site CF band at 1.20 microns. Such interference would be a major problem if in situ reflectance spectra could be measured on the surface of Venus where ambient temperatures are as high as 475 C. Disordering of Fe(2+) and Mg(2+) ions comparable to that in the orthopyroxenes used in this spectral chemical study might be expected in low Ca pyroxenes occurring on the Venusian surface. Researchers conclude that Fe(2+)/M1 site spectral features need to be carefully assessed in remote-sensed spectra before deductions are made about the presence of olivine on planetary surfaces.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1990; p 253-255
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