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  • Articles  (20)
  • Geochemistry  (12)
  • X-ray structure  (8)
  • Springer  (20)
  • 2015-2019
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  • 1945-1949
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  • Articles  (20)
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  • 1
    Electronic Resource
    Electronic Resource
    The synthesis and crystallographic characterization of the heterobimetallic dodecanuclear cage cluster: [Et4N]2[(Mo2Ag2S2O2edt2)3(μ6-S)]·3H2O (edt=−SC2H4S−) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 55-60 
    Details
    ISSN: 1572-8854
    Keywords: heterobimetallic ; dodecanuclear ; Mo-Ag-S cage cluster ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the title compound, [Et4N]2[(Mo2Ag2S2O2edt2)3(μ6-S)]·3H2O (edt=SC2H4S−), has been investigated by X-ray diffraction techniques, the crystal is tetragonal, space group P4l2l2, with a = b = 13.4801(4), c = 37.7381(14) Å, V = 6857.5(4) Å3 andZ = 4. The anion of the title compound can be viewed as a cage consisting of three [Mo2S2O2(S2C2H4)2]2−/2 Ag+ fragments, with an S2− at the cage center bonding to six Ag atoms. The cage has two big windows each composed of a puckered Ag3S6C6 15-membered ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009550200651
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  • 2
    Electronic Resource
    Electronic Resource
    X-ray structure of [(μ-H)Os3(CO)10(μ-1,8-η2-C9H6N)] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 773-776 
    Details
    ISSN: 1572-8854
    Keywords: X-ray structure ; triosmium cluster ; decacarbonyl ; quinoline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Decacarbonyl-μ-hydrido-μ-1,8-η2-quinoline-triosmium crystallizes in the triclinic space group P $$\bar 1$$ with a = 7.8551(6), b = 9.1283(8), c = 16.7915(8) Å, α = 74.788(2), β = 88.086(2), γ = 66.392(3)°, V = 1062.22(13)° Å3, T = 150 K, and Z = 2. The molecule consists of an Os3 triangle with the hydride and the heterocyclic ligand bridging the same Os—Os edge. The heterocyclic ligand is coordinated through the C(8) carbon and nitrogen atoms in a new μ-1,8-η2-bonding mode. The Os—Os distances lie in the close range 2.8837(4)–2.9034(4) Å with an average value of 2.892(7) Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013268023526
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray diffraction structure of the phosphido-bridged mixed-metal cluster Fe2(CO)6(μ3-PPh)2Pt(dppe) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 233-236 
    Details
    ISSN: 1572-8854
    Keywords: Mixed-metal clusters ; phosphido-bridged clusters ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Treatment of Fe2(CO)6(μ2-PPhH)2 with BuLi (2 equiv.), followed by the addition of PtCl2 (dppe), affords the phosphido-bridged cluster Fe2(CO)6(μ3-PPh)2Pt(dppe). The Fe2Pt cluster was isolated and characterized in solution by IR and 31P NMR spectroscopy, and the molecular structure of Fe2(CO)6(μ3-PPh)2Pt(dppe) determined by X-ray diffraction analysis. Fe2(CO)6(μ3-PPh)2Pt(dppe) crystallizes in the orthorhombic space group Pbca, a = 17.539(3) Å, b = 21.490(2) Å, c = 22.959(3) Å, V = 8653.5(18) Å3, Z = 8, dcalc = 1.670 g cm−3; R = 0.0644, Rw = 0.0389 for 5040 observed reflections with I 〉 3σ(I).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009586921599
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  • 4
    Electronic Resource
    Electronic Resource
    Crystal structure of the nonlinear optical compound L-arginine fluoride (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 411-414 
    Details
    ISSN: 1572-8854
    Keywords: L-arginine fluoride ; second harmonic generator ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract L-arginine fluoride is a promising compound that exhibits nonlinear optical properties. It efficiently converts two single photons of the same polarization and frequency ω to one photon of frequency 2ω (type I phase matching). C6H15N4O2 +F− is monoclinic, space group P21, a = 5.4475(4) Å, b = 8.5133(6) Å, c = 10.2195(7) Å, β = 93.475(6)°. The cation has a zwitterionic form, protonated at both the guanidyl and amino groups. The arginine Cγ atom is in a trans position to the carboxyl group. A complex three-dimensional hydrogen bond network links the anions and cations together.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009586023285
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  • 5
    Electronic Resource
    Electronic Resource
    Spectroscopic study of phosphine selenide complexes of Au(I) and X-ray structure of [(cyclohexyl)3PSeAuBr] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 731-735 
    Details
    ISSN: 1572-8854
    Keywords: phosphine selenide ; Au(I) ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray structure determination of the complex, [(cyclohexyl)3PSe-AuBr], revealed a triclinic space group P-1, with a = 9.7654(7), b = 10.9441(9), c = 11.2064(9) Å, α = 117.076(6)°, β = 99.076(6)° γ = 95.417(6)°, V = 1034.07(14) Å3 and Z = 2. The Au(I) atom in this complex has a linear coordination with Se1 atom at 2.3776(9) Å on one side and Br1 at 2.3843(9) Å at the trans position making the Se1-Au1-Br1 angle of 177.97(4)°. The P1 atom in the phosphine has tetrahedral geometry. All three cyclohexyl groups are in their usual boat conformation. The phosphorus atom of the triphenylphosphine is approximately perpendicular to the Se1—Au1—Br1 linkage with P1—Se1—Au1 angle of 99.19(6)°. The Δδ in the 31P NMR of the free ligands and their corresponding L—Se—Au—Br (L—Se = trialkyl/arylphosphine selenides) complexes, and the changes in the P—Se bond frequencies in the FTIR upon complexation, are indicative of the bonding of the ligand to Au(I) through selenium. There is a strong corelation between the chemical shifts of the 31P NMR and the C—P—C angle in the phosphines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012202328695
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular and crystal structure of [NO2Py]2[Ni(mnt)2](NO2Py=1-(4-nitrobenzyl)pyridinium, mnt2−=maleonitriledithiolate) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 91-94 
    Details
    ISSN: 1572-8854
    Keywords: 1-(4-Nitrobenzyl)pyridinium ; bis(maleonitriledithiolato)nickelate(II) complex ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of [NO2Py]2[Ni(mnt)2], as determined by x-ray single crystal analysis, consists of two 1-(4-nitrobenzyl)pyridinium cations and one [Ni(mnt)2]2− anion. The crystallographic data for the complex:monoclinic P21/n, a = 9.913(2) Å, b = 11.968(2) Å, c = 14.566(3) Å, β = 100.36(3)°, V = 1699.9(6) Å3, Z = 2. The [Ni(mnt)2]2− anion has a crystallographically imposed center of symmetry and exhibits a relatively planar structure. The cation, [NO2Py]+, adopts a conformation where both the aromatic rings are twisted to the C11-C10-N3 reference plane. The anions (A) and the cations (C) consist of alternating layers (i.e., of type ···C1A1C2A2C1A1C2···) along the c axis of the crystallographic unit cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009509427097
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  • 7
    Electronic Resource
    Electronic Resource
    X-ray structural analysis of a copper(I) adduct of the Rh(III) trihydride [(triphos)RhH3], with triphos = CH3C(CH2PPh2)3 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 321-328 
    Details
    ISSN: 1572-8854
    Keywords: Rhodium ; copper ; hydride ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The binuclear compound [(triphos)RhH(μ-H)2Cu(diphos*)]+ with triphos = CH3C(CH2PPh2)3 and diphos* = o-C6H4(CH2P(C6H11)2)2 has been prepared and characterized. It crystallizes as [CF3SO3] salt in the monoclinic P21/c space group with Z = 4, a = 13.802(4)Å, b = 19.462(4)Å, c = 26.604(5)Å, β = 99.8(3)°, and V = 7041(3)Å3. The structure of the complex consists of two metal fragments with hydride ligands bridging the Rh-Cu contact. The hydride ligands were not located by X-rays but, from the arrangement of the heavy atoms and by methods of potential energy, the most probable positions of two hydride ligands bridging the Rh-Cu interaction and one that remains terminal on the rhodium atom, were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009509207702
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  • 8
    Electronic Resource
    Electronic Resource
    Reactions of [Mn2(μ-pyS)2(CO)6] with bidentate phosphines: X-ray structure of [Mn(η2-pyS) (η2-dppp)(CO)2] [dppp = Ph2P(CH2)3PPh2, pySH = pyridine-2-thiol] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 379-383 
    Details
    ISSN: 1572-8854
    Keywords: Manganese ; pyridine-2-thiolate ; bis(diphenylphosphino)propane ; X-ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 molar equivalents of Ph2P(CH2)3PPh2 (dppp) and Ph2P(CH2)2PPh2 (dppe) to give the respective monomeric chelate complexes [Mn(η2-pyS)(η2-dppp)(CO)2] (2) and [Mn(η2-pyS)(η2-dppe)(CO)2] (3). In contrast, with 2 molar equivalents of Ph2P(CH2)5PPh2 (dpppe), 1 gave the highly insoluble polymeric complex [Mn(η2-pyS)(μ-dpppe)(CO)2]n (4). An X-ray structure determination shows that 2 crystallizes in the monoclinic space group P21/n with a = 10.721(2) Å, b = 19.712(5) Å, c = 14.846(4) Å, β = 109.06(2)°, V = 2965.5(14) Å3, and Z = 4. The complex has a distorted octahedral geometry with the dppp ligand, one CO group and the N atom of the chelating pyS ligand occupying equatorial sites, and one CO group and the S atom of the pyS ligand lying in the axial positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009525704630
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  • 9
    Electronic Resource
    Electronic Resource
    Shallow pore water sampling in reef sediments (2000)
    Springer
    Coral reefs 19 (2000), S. 93-97 
    Details
    ISSN: 1432-0975
    Keywords: Key words Sampling ; Sediment ; Geochemistry ; Pore water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Several new techniques have been developed to allow the geochemical characterization of shallow pore waters in reefs. First, a new method was developed for using non-metallic well-points to sample pore waters from shallow depths (〈1 m) in coral reefs with unconsolidated substrates. These PVC well-points can be made faster and at less expense than well-points made of stainless steel. They also eliminate metal contamination and are free from the problems of corrosion in sea water. Additional improvements in sampling techniques maximize the spatial resolution of geochemical gradients and address the problems of atmospheric contamination associated with the sampling of dissolved gases. Data taken from Checker Reef, Oahu, Hawaii, illustrate the application of these methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380050233
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  • 10
    Electronic Resource
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    Geochemistry, petrogenesis and tectonic setting of late Neoproterozoic Dokhan-type volcanic rocks in the Fatira area, eastern Egypt (2000)
    Springer
    International journal of earth sciences 88 (2000), S. 764-777 
    Details
    ISSN: 1437-3262
    Keywords: Key words Neoproterozoic ; Dokhan volcanics ; Egypt ; Geochemistry ; Petrogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Neoproterozoic Dokhan volcanics of the Fatira area in eastern Egypt comprise two main rock suites: (a) an intermediate volcanic suite, consisting of basaltic andesite, andesite, dacite, and their associated pyroclastic rocks; and (b) a felsic volcanic suite composed of rhyolite and rhyolitic tuffs. The two suites display well-defined major and trace element trends and a continuum in composition with wide ranges in SiO2 (54–76%), CaO (8.19–0.14%), MgO (6.96–0.04%), Sr (983–7 ppm), Zr (328–95 ppm), Cr (297–1 ppm), and Ni (72–1 ppm). They are enriched in LILEs (Rb, Ba, K, Th, Ce) relative to high field strength elements (Nb, Zr, P, Ti) and show strong affinity to calc-alkaline subduction-related rocks. However, their undeformed character, their emplacement temporally and spatially with post-orogenic A-type granite, and their high Zr/Y values suggest that their emplacement follow the cessation of subduction in eastern Egypt in an extensional-related within-plate setting. Major and trace element variations in the intermediate volcanics are consistent with their formation via partial melting of an enriched subcontinental lithospheric mantle source followed by a limited low-pressure fractional crystallization of olivine and pyroxene before emplacement. The LILE enrichment relative to HFSE is attributed to the inheritance of a subduction component from mantle material which constituted the mantle wedge during previous subduction events in eastern Egypt. The evolution of the whole volcanic spectrum was governed mainly by crystal/melt fractionation of amphibole, plagioclase, titanomagnetite, and apatite in the intermediate varieties and plagioclase, amphibole, biotite, Fe–Ti oxides, apatite, and zircon in the felsic varieties. At each stage of evolution, crystal fractionation was accompanied by variable degrees of crustal contamination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050304
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  • 11
    Electronic Resource
    Electronic Resource
    Zircon ages and Nd isotopic and chemical compositions of orthogneisses from the Black Forest, Germany: evidence for a Cambrian magmatic arc (2000)
    Springer
    International journal of earth sciences 88 (2000), S. 791-802 
    Details
    ISSN: 1437-3262
    Keywords: Key words Variscan belt ; Moldanubian zone ; Black Forest ; Orthogneiss ; Zircon dating ; ¶Nd isotopes ; Geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Single zircon U–Pb dating combined with 207Pb/206Pb ages obtained by the evaporation method constrains the emplacement of tonalitic, trondhjemitic, and granodioritic orthogneisses of the Moldanubian zone in the Black Forest between 500 and 510 Ma. Two detrital zircon populations of 1.9 and 1.6 Ga indicate Early-Middle Proterozoic material in the former setting of the basement. The initial eNd values range from –0.1 to –3.4 and mean crustal residence ages of 1.0–1.4 Ga are consistent with involvement of Early-Middle Proterozoic crust, and a subordinate juvenile component probably originating from subduction-related melting of the mantle. The orthogneisses have fractionated REE patterns and slightly higher K2O/Na2O ratios than typical low-K tonalite–trondhjemite–granite suites. The chemical data are interpreted as evidence for melting of amphibolite and contributions from evolved crust. The emplacement of the orthogneisses was superceded by a high-temperature metamorphic event at ∼480 Ma which we interpret as a result of lithospheric thinning in a marginal basin behind a Cambrian magmatic arc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050306
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  • 12
    Electronic Resource
    Electronic Resource
    Upper Neoproterozoic–Lower Cambrian sedimentary successions in the Central Iberian Zone (Spain): sequence stratigraphy, petrology and chemostratigraphy. Implications for other European zones (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 2-20 
    Details
    ISSN: 1437-3262
    Keywords: Lithostratigraphy ; Petrology ; Geochemistry ; Sedimentology ; Sequence stratigraphy ; Late Neoproterozoic ; Lower Cambrian ; Central Iberian Zone ; Iberian Massif
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: 2 O3, TiO2, Zr, and Nb abundances in shales from all the units, strongly suggest a gradual compositional change within this sedimentary succession. Together with the petrological data, the chemical results do not reveal any obvious coeval volcanic contribution to the sediments. On the basis of the chemical data, a comparison is made with other European zones containing detrital sediments composed of reworked crustal components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050314
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  • 13
    Electronic Resource
    Electronic Resource
    Some constraints on geochemical features in the Triassic mantle of the easternmost Austroalpine–Southalpine domain: evidence from the Karawanken pluton (Carinthia, Austria) (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 40-51 
    Details
    ISSN: 1437-3262
    Keywords: Karawanken pluton ; Eastern Alps ; Triassic ; Petrology ; Geochemistry ; Rb ; Sr age ; Triassic mantle ; Transtensional ; extensional tectonics ; Mesozoic rifting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050316
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  • 14
    Electronic Resource
    Electronic Resource
    Geochemical compositional changes at the Pliocene–Pleistocene transition in fluviodeltaic deposits in the Tegelen-Reuver area (southeastern Netherlands) (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 154-169 
    Details
    ISSN: 1437-3262
    Keywords: Geochemistry ; Clay mineralogy ; Weathering ; Diagenesis ; Rhine ; Facies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: 2 O contents, which can be attributed to the Alpine source supplying fresh, sodic plagioclase-rich material instead of the local, strongly weathered sediments. Increasing K2O/Al2O3 can be attributed to a similar decrease in degree of weathering. However, this trend is disturbed by the loss of K from clay minerals during weathering in organic-rich layers. Local high TiO2 anomalies, caused by preferential sorting and concentration, are found in most Pliocene sections, but they are absent in the Upper Pliocene and Lower Pleistocene Alpine-derived deposits. This change is probably due to a change in the energy of the fluvial system. Finally, (pyrite-) S contents drop (siderite-) Fe contents rise. Micromorphological observations indicate that the Pliocene pyrite was formed when freshwater deposits were flooded with seawater during short-term events. The decrease in S, and the increase in siderite-Fe, can be attributed to decreasing marine influence, as a result of the marine regression at the Pliocene–Pleistocene transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050323
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  • 15
    Electronic Resource
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    Relics of an early-Panafrican metabasite–metarhyolite formation in the Brno Massif, Moravia, Czech Republic (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 328-335 
    Details
    ISSN: 1437-3262
    Keywords: Key words Central European Variscides ; Brno Massif ; Metarhyolite ; Metabasite complex ; Geochemistry ; Zircon geochronology ; Cadomian ; Panafrican
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Brno Massif in Moravia, Czech Republic, is an important exposure of Precambrian basement in central Europe. It includes large volumes of Cadomian granitoids and a narrow fault-bounded zone with metagabbros, metadiorites, and metabasalts. This so-called Central Basic Belt also contains some metarhyolites; one of these was dated by means of the zircon evaporation method at 725 ±15 Ma. Chemical and isotope data show that the dated rock represents a mantle-derived magma which is cosanguinous with surrounding MORB-type metabasites. The data suggest that the Brno Massif hosts the oldest metabasite complex currently known in central Europe. Its formation apparently coincides with the main period of ocean-floor spreading and island-arc formation in the Panafrican orogens. This lends further support to the theory that the Brno Massif is a Gondwana-derived element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310000084
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  • 16
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    Geochemical background – can we calculate it? (2000)
    Springer
    Environmental geology 39 (2000), S. 990-1000 
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    ISSN: 1432-0495
    Keywords: Key words Background ; Data distribution ; Normal distribution ; Log-normal distribution ; Geochemistry ; Environmental science ; Robust geostatistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The term "background" is discussed and a definition is suggested to put an end to the currently unsatisfying (non-)definition of geochemical or natural background. Based on the requirements stated in the definition, several simple and robust statistical methods are applied to different data sets (n〉50) from the atmosphere, pedosphere, and biosphere in order to explore their potential for the evaluation of a useful and robust background. Compared with the original data set both the calculated distribution, based upon the lower 50% of the values, as well as a 2σ-approximation of the normalised data set lead to promising and realistic results. Both methods seem appropriate for a fast and reliable evaluation of likely upper limits of background values. Nevertheless, even this robust method is not able to present absolute and doubtlessly correct background values. True quantification of any natural or geochemical background still requires a thorough investigation and is impossible without costly expert knowledge.
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    URL: http://dx.doi.org/10.1007/s002549900084
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  • 17
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    Pit lakes: their characteristics and the potential for their remediation (2000)
    Springer
    Environmental geology 39 (2000), S. 1254-1260 
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    ISSN: 1432-0495
    Keywords: Key words Mine ; Pit lake ; Geochemistry ; Remediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Pit lakes form when open-pit mining operations are discontinued and dewatering ceases. The increase in open-pit metal mining since the 1970s will lead to the formation of numerous pit lakes over the next 50 years. Many of these lakes will develop acid sulfate conditions with high levels of dissolved metals. Approaches to remediation of these conditions that have been recommended include the addition of lime or other alkaline materials and the stimulation of sulfate-reducing bacteria. However, prevention rather than remediation is probably the preferable approach. Measures to prevent oxidation of mining waste and wall rocks, including measures to fill pits quickly with water, to inhibit the activity of acidophilic sulfur-oxidizing bacteria, and to promote anoxic conditions at the lake bottoms may minimize the formation of acids and dissolved metals.
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    URL: http://dx.doi.org/10.1007/s002549900100
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  • 18
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    Geographical variations of trace elements in sediments of the major rivers in eastern China (2000)
    Springer
    Environmental geology 39 (2000), S. 1334-1340 
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    ISSN: 1432-0495
    Keywords: Keywords China ; Geochemistry ; River ; Sediment ; Trace metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A total of 26 geographically and hydrologically diverse sediment samples were collected from 12 major rivers in eastern China. The 〈63-μm fraction of the sediments was analysed for both total concentrations of Cu, Zn, Pb and Cd, and their associations with various geochemical phases. The geographical variations of sediment-bound trace metals can be related to the bedrock types and weathering processes in the corresponding river basins. The rivers in southern China had notably higher concentrations of trace metals in sediments because of abundant non-ferrous mineral deposits and stronger weathering process in the region. A large proportion of trace metals in these sediments was associated with iron and manganese oxides and organic matter. Relative low levels of trace metals were found in river sediments in northern China, and a significant proportion of the metals was bound to organic matter, carbonates, and the residual fraction. The sediments in the Yellow River, originating from special loess, had the lowest concentrations of trace metals. Most of the trace metals were associated with the carbonates and residual phases.
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    URL: http://dx.doi.org/10.1007/s002540000224
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  • 19
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    Normal and lognormal data distribution in geochemistry: death of a myth. Consequences for the statistical treatment of geochemical and environmental data (2000)
    Springer
    Environmental geology 39 (2000), S. 1001-1014 
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    ISSN: 1432-0495
    Keywords: Key words Normal distribution ; Lognormal distribution ; Geochemistry ; Exploratory data ; analysis ; Multivariate normal distribution ; Robust methods ; Non-parametric methods ; Median
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract All variables of several large data sets from regional geochemical and environmental surveys were tested for a normal or lognormal data distribution. As a general rule, almost all variables (up to more than 50 analysed chemical elements per data set) show neither a normal or a lognormal data distribution. Even when different transformation methods are used more than 70 % of all variables in every single data set do not approach a normal distribution. Distributions are usually skewed, have outliers and originate from more than one process. When dealing with regional geochemical or environmental data normal and/or lognormal distributions are an exception and not the rule. This observation has serious consequences for the further statistical treatment of geochemical and environmental data. The most widely used statistical methods are all based on the assumption that the studied data show a normal or lognormal distribution. Neglecting that geochemcial and environmental data show neither a normal or lognormal distribution will lead to biased or faulty results when such techniques are used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002549900081
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  • 20
    Electronic Resource
    Electronic Resource
    A model for the magmatic–hydrothermal system at Mount Rainier, Washington, from seismic and geochemical observations (2000)
    Springer
    Bulletin of volcanology 61 (2000), S. 425-436 
    Details
    ISSN: 1432-0819
    Keywords: Key words Mount Rainier ; Seismicity ; Geochemistry ; Magmatic–hydrothermal system model ; Volcano monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Mount Rainier is one of the most seismically active volcanoes in the Cascade Range, with an average of one to two high-frequency volcano-tectonic (or VT) earthquakes occurring directly beneath the summit in a given month. Despite this level of seismicity, little is known about its cause. The VT earthquakes occur at a steady rate in several clusters below the inferred base of the Quaternary volcanic edifice. More than half of 18 focal mechanisms determined for these events are normal, and most stress axes deviate significantly from the regional stress field. We argue that these characteristics are most consistent with earthquakes in response to processes associated with circulation of fluids and magmatic gases within and below the base of the edifice.Circulation of these fluids and gases has weakened rock and reduced effective stress to the point that gravity-induced brittle fracture, due to the weight of the overlying edifice, can occur. Results from seismic tomography and rock, water, and gas geochemistry studies support this interpretation. We combine constraints from these studies into a model for the magmatic system that includes a large volume of hot rock (temperatures greater than the brittle–ductile transition) with small pockets of melt and/or hot fluids at depths of 8–18 km below the summit. We infer that fluids and heat from this volume reach the edifice via a narrow conduit, resulting in fumarolic activity at the summit, hydrothermal alteration of the edifice, and seismicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008909
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