Hollandite–strontiomelane solid solutions coexisting with kanonaite and braunite in late quartz veins of the Stavelot Massif, Ardennes, Belgium     

Werner Schreyer  André-Mathieu Fransolet  Heinz-Jürgen Bernhardt 《Contributions to Mineralogy and Petrology》2001,141(5):560-571

In a newly found type of quartz vein cross-cutting the famous "viridine"-bearing phyllites at Le Coreux, hollandite, ideally BaMn₈O₁₆, was discovered for the first time at this locality and in Belgium. Because the crystals contain up to 60 mol% of the Sr end member, this is also the second occurrence of strontiomelane. The coexisting "viridine" (= kanonaite) contains the highest amount (88 mol%) of the ideal end member MnAlSiO₅ ever found worldwide. The hollandite-type minerals are intimately intergrown with braunite containing appreciable Ca and Mg. Ba-bearing muscovite, Fe-poor excess-Al clinochlore (not quite trioctahedral), and albite are the remaining accessory minerals in the dominant quartz matrix. Microprobe analyses of all phases show rather extreme element fractionations: nearly all K is located in muscovite and none in the hollandite phase despite the existence of the end member KMn₈O₁₆ (cryptomelane). Similarly, nearly all Na is in albite and not in hollandite (no NaMn₈O₁₆=manjiroite component). Nearly all Mn resides in the two oxide phases and in kanonaite. Mg is strongly fractionated into chlorite. The small amounts of Fe and Ti present are predominantly partitioned into the hollandite phase, which also accommodates most of the Ba and Sr. Indeed, the hollandite phase is stabilized by the latter two elements relative to other Mn oxides. Kanonaite is stabilized by Al. Although no requisite sites are available in its crystal structure, braunite always contains small amounts of Ba and Sr. However, the Sr/(Sr+Ba) ratios in braunite are spurious and unrelated to those of the directly adjoining hollandite phases The conditions of formation of these veins may be well below 300 °C at low pressures (1-2 kbar), in agreement with the experimental results that the maximum Mn contents in kanonaite increase with falling temperatures.  相似文献   

Mass transfer in hydrothermal alteration systems—A conceptual approach     

Werner F. Giggenbach 《Geochimica et cosmochimica acta》1984,48(12):2693-2711

At very low fluid/rock mass ratios the hydrothermal alteration process corresponds to isochemical recrystallisation of the primary rock. The resulting full equilibrium assemblage with the composition of an average crustal rock contains the phases albite, K-feldspar, K-mica, biotite, quartz and (depending on temperature) epidote, prehnite or one of the Ca-zeolites. Relative Na⁺, K⁺, Mg²⁺ and Ca²⁺—solution activities in such a rock-dominated alteration system are uniquely fixed and provide useful reference points with regard to the degree of attainment of full fluid/rock equilibrium. With increasing fluid/rock mass ratios the composition of now increasingly fluid-dominated alteration assemblages is determined by the interplay of three major processes: hydrogen metasomatism as a function of CO₂ reactivity increasing with the horizontal distance from major fluid upflow zones and leading to the formation of Al-enriched alteration assemblages; potassium metasomatism accompanied by silicification in or close to major fluid upflow zones leading to potassic and phyllic alteration; sodium, magnesium, calcium metasomatism associated with descending and heating solutions leading to propylytic alteration of recharge zones. Two new parameters, reactivity and exchangeability, determining the effectiveness of fluid components with respect to hydrothermal alteration are introduced.  相似文献   

Effect of organic acids and fluoride on the dissolution kinetics of hydrous alumina. A model study using the rotating disc electrode     

Vera Žutić  Werner Stumm 《Geochimica et cosmochimica acta》1984,48(7):1493-1503

The dissolution of aluminium oxide was studied with an oxide film covered rotating disc aluminium electrode. This allows us to make measurements under conditions of well defined mass transport under conditions representative of those found in natural waters (conc. of Al, organic acids and fluoride), and permits us to distinguish between surface-controlled and transport-controlled rates.Under steady-state conditions, the dissolution current is a direct measure of the flux of dissolving Al ions at the aqueous interface of the amorphous hydrous oxide film.At pH 3–6 and in presence of organic ligands, dissolution is controlled by a surface process, i.e. the rate of detachment of surface complexes. Fluoride ions in concentrations ≥ 10^?6 M increase dramatically the dissolution rate: at pH = 4 the process is controlled by convertive diffusion of F^? from the solution to the surface (k_F- = (3.6 ± 0.5) × 10^?2cms^?1). Competitive and reversible adsorption of organic ligands (10^?6 ? 10^?2M) displacing fluoride slows down the rate of detachment of the surface complex which becomes the rate-limiting step. The affinity of ligands for the Al₂O₃ surface sites increases in the sequence: formate ~ chloride ~ carbonate < acetate < sulphate < salicylate < fumarate < maleate < malonate ? oxalate ? fluoride ≤ citrate.The results are compared with simulated weathering experiments and interpreted in terms of the surface complexation model.  相似文献   

Is dissolved Mn2+ being oxidized by O2 in absence of Mn-bacteria or surface catalysts?     

Dieter Diem  Werner Stumm 《Geochimica et cosmochimica acta》1984,48(7):1571-1573

Homogeneous Mn(II) solutions that are not oversaturated with respect to MnCO₃ or Mn(OH)₂, in the absence of catalysts, remain in the presence of dissolved oxygen unoxidized for periods in excess of seven years. Measurable oxygenation rates are observed in solutions that are oversaturated with respect to MnCO₃ or in waters containing “Mn-bacteria” or other surface catalysts.  相似文献   

Paleozoic basin development in northern Chile (21°–27°S)     

Dr. Heinrich Bahlburg  Dr. Christoph Breitkreuz  Prof. Dr. Werner Zeil 《International Journal of Earth Sciences》1987,76(2):633-646

The oldest non-metamorphic sediments of northern Chile (21?–27?S) are of Early Ordovician age. The partly strong volcanic influence in the clastic series of the Pre-Cordillera and the Puna might be connected with the extensive Ordovician magmatism on the eastern side of the Argentinian Puna. The geochemical character of the tholeiitic intercalations in the pelites and turbidites of the »Complejo Igneo-Sedimentario del Cordon de Lila« (C.I.S.L.) in the Pre-Andean Depression indicates a ?Lower Ordovician extensional regime in this area. A positive area (»Arco Puneño«) encompassing the whole width of the present-day western Central Andes developed during the subsequent orogenic phase (»Fase Oclóyica«), resulting in the absence of Silurian strata in Northern Chile. During the Devonian/Carboniferous, two areas of marine facies can be distinguished. In the Coastal Cordillera thick flysch sediments were deposited longitudinally in a N-S striking trough. In the east, in what is now the Pre-Andean Depression and High Cordillera, thick sandstone series accumulated on the western shelf of the Arco Puneno. Carboniferous tectonic movements led to the formation of a shallow marine platform in the west on which clastic sediments, limestones and volcanics were deposited during the Upper Carboniferous-Permian. Simultaneously, extensive volcanism developed in the Pre- and High Cordillera accompanied by predominantly terrestrial sedimentation. A general westward migration of the orogenic zones took place along with repeated phases of rifting and accretion in the Central Andes during the Paleozoic. Eastward directed erosive subduction prevailed since the breakup of Pangea.  相似文献   

Beziehungen zwischen Gesteinsdeformation und Schallgeschwindigkeiten     

Professor Dr. Werner Plessmann  Prof. Dr.-Ing. Gerhard Spaeth 《International Journal of Earth Sciences》1972,61(3):1010-1019

Zusammenfassung Im Rheinischen Schiefergebirge verlaufen die höchsten Schallgeschwindigkeiten normalerweise parallel b. Taucht bei starker Verformung eine Faser in Richtung a auf, liegen die schnellsten Schallimpulse in a. Die Anordnung der Phyllosilikate ist Ursache dieser Anisotropie.

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In the Rheinisches Schiefergebirge the seismic velocities in most cases are parallel b. In regions with a strong deformation and a linear element in a, the highest velocities correspond with the same direction. This anisotropy is caused by the position of the phyllosilicates.

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Résumé Dans le Massif schisteux rhénan, les ondes sonores ont normalement leur plus grande vitesse de propagation dans la direction parallèle à « b ». Dans les roches tectoniquement déformées et caractérisées par une linéation selon « a », la plus grande vitesse se retrouve dans cette direction. Cette anisotropie est causée par la disposition des phyllosilicates.

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Zur Geologie der Anden     

Prof. Dr. Werner Zeil 《International Journal of Earth Sciences》1970,59(3):827-834

Zusammenfassung Es wird ein Überblick über einige grundlegende Merkmale der Geologie der Anden gegeben. Der Stand der geologischen Forschung wird kurz skizziert.

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Some principal aspects of the geology of the Andes are reviewed. The present state of geological research is briefly described.

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Résumé L'auteur présente un aperçu sur les principales données de la géologie des Andes. La situation actuelle de la reconnaissance géologique est brièvement esquissée.

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Ein Versuch zur numerischen Bestimmung des vertikalen Austauschkoeffizienten für Wasserdampf in der wassernächsten Luftschicht     

Dr. Julius Werner 《Meteorology and Atmospheric Physics》1971,20(2):159-174

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Trace element distribution in Chilean ignimbrites     

Prof. Dr. Essam E. El-Hinnawi  Hans Pichler  Werner Zeil 《Contributions to Mineralogy and Petrology》1969,24(1):50-62

The geochemistry of Chilean ignimbrites is discussed in terms of major and trace elements. The variation in the major elements and in the distribution of Ba, Co, Cu, Ga, Pb, Sn, Sr, V, and Zr with the differentiation factor (1/3Si+K)-(Ca+Mg) has been studied. The general trend is that characteristic of calc-alkaline rhyolite-dacite-andesite associations. Exceptionally high values of copper reported and high values of Sn and Zr provide further evidence of the anatectic origin of these ignimbrites.  相似文献   

Sedimentation in der Magallanes-Geosynklinale mit besonderer Berücksichtigung des Flysch     

Werner Zeil 《International Journal of Earth Sciences》1958,47(1):425-443

Zusammenfassung Der Bau des südlichen Abschnittes der Anden wird knapp skizziert. Geländearbeiten in Magallanes, Chile, ergaben neue Vorstellungen über die Sedimentation und das Alter sowie die Fazies einiger Schichtfolgen in Unter- und Oberkreide.Die Entstehung der Konglomerate der Serie Lago Sofia ist nicht auf eine Vereisung in der Oberkreide zurückzuführen, sondern es handelt sich um eine Grobschüttung, die nach fluviatilem Transport deltaförmig in einen Flachwasserbereich gelangte. Das Alter der Konglomerate ist Campan/Grenze Maastricht. Damit ist die Serie Lago Sofia mit den Konglomeraten der Serie Valdez in Feuerland zu parallelisieren. Eine Nord-Süd-Störung innerhalb der Geosynklinale besteht zumindest im Raum zwischen Cerro Toro und Cerro Cazador nicht.Der oberkretazische Flysch in Süd-Chile ist nicht in einem eigenen Trog entwickelt, sondern stellt eine zeitlich gebundene Fazies innerhalb der Geosynklinale dar. In Fazies, Petrographie und Fauna wird eine weitgehende Übereinstimmung mit dem ostalpinen Flysch festgestellt. Der Hinweis auf eine einheitliche Flyschzone, die von der mittleren Magallanes-Geosynklinale bis zum Grahamland reicht, stützt die von O.Wilckens mehrfach postulierte Einheitlichkeit des Süd-Antillen-Bogens.

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Resumen Después de una ojeada a la constitución tectónica y a la estratigrafía del geosinclinal medio de Magallanes, se proporcionan algunos datos sobre la sedimentación. Con mayor detenimiento son estudiadas la composición, génesis y situación estratigráfica de los conglomerados de la Serie Lago Sofia.El flysch del cretácico superior que se halla entre el Lago Sarmiento y el Golfo Almirante Montt, presenta una considerable coincidencia con el flysch de los Alpes orientales, así como con la zona de flysch de la Tierra del Fuego y de las Antillas meridionales. La zona de flysch señalada desde el geosinclinal inedio de Magallanes, pasando por la Tierra del Fuego hasta Grahamlandia, apoya la tesis de la unidad del arco de las Antillas meridionales, defendida repetidamente por O.Wilckens.

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