Ilmenite composition in the Tellnes Fe–Ti deposit,SW Norway: fractional crystallization,postcumulus evolution and ilmenite–zircon relation

Major and trace element XRF and in situ LA-ICP-MS analyses of ilmenite in the Tellnes ilmenite deposit, Rogaland Anorthosite Province, SW Norway, constrains a two stage fractional crystallization model of a ferrodioritic Fe-Ti-P rich melt. Stage 1 is characterized by ilmenite-plagioclase cumulates, partly stored in the lower part of the ore body (Lower Central Zone, LCZ), and stage 2 by ilmenite-plagioclase-orthopyroxene-olivine cumulates (Upper Central Zone, UCZ). The concentration of V and Cr in ilmenite, corrected for the trapped liquid effect, (1) defines the cotectic proportion of ilmenite to be 17.5 wt% during stage 1, and (2) implies an increase of D _V^Ilm during stage 2, most likely related to a shift in fO₂. The proportion of 17.5 wt% is lower than the modal proportion of ilmenite (ca. 50 wt%) in the ore body, implying accumulation of ilmenite and flotation of plagioclase. The fraction of residual liquid left after crystallization of Tellnes cumulates is estimated at 0.6 and the flotation of plagioclase at 26 wt% of the initial melt mass. The increasing content of intercumulus magnetite with stratigraphic height, from 0 to ca. 3 wt%, results from differentiation of the trapped liquid towards magnetite saturation. The MgO content of ilmenite (1.4–4.4 wt%) is much lower than the expected cumulus composition. It shows extensive postcumulus re-equilibration with trapped liquid and ferromagnesian silicates, correlated with distance to the host anorthosite. The Zr content of ilmenite, provided by in situ analyses, is low (<114 ppm) and uncorrelated with stratigraphy or Cr content. The data demonstrate that zircon coronas observed around ilmenite formed by subsolidus exsolution of ZrO₂ from ilmenite. The U-Pb zircon age of 920 ± 3 Ma probably records this exsolution process. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Mineralogical,geochemical and microfabric evidences of gypsum crusts: a case study from Budapest

High levels of SO₂ and particulate pollution enable the rapid development of gypsum-rich weathering crusts in Budapest. Two types of white crusts, thin and thick ones, and two forms of black crusts, laminar and framboidal ones, were studied in limestone buildings of the parliament and Citadella. The percentage of crust cover and damage categories were documented on selected walls. Petrographic, XRD, XRF and sulphur isotope analyses were performed under laboratory conditions to understand the mechanism of crust formation. White crusts found both on exposed and sheltered walls display a calcite-rich layer with gypsum, while black crusts are enriched with gypsum. The sulphur isotopic composition of white and black crusts overlaps, but the crusts are slightly enriched in heavy isotopes compared to rainwater. S content, Si/Al ratios and particulates in black crusts suggest that air pollution (SO₂, dust) contributes to black crust formation. The accumulation of sulphur and Zn enrichment of white crusts were also documented indicating that under high pollution levels, even these compound can accumulate on exposed facades.     

Possibilities of GPS Kinematic Measurements for Geological Survey in East Slovakia

This paper deals with transformation procedures for observed GPS data from the world geodetic system WGS-84 into the national geodetic grid datum S-UTCN(system of united trigonometric cadaster network) and Baa(the Baltic Sea after adjustment).Transformation from WGS-84 into SUTCN is performed most frequently by means of the 7-element Helmert transformation with three identical points.Geodetic network was adjusted by two ways.     

Improved indirect phase reflection height measurement at panská ves — method,equipment, evaluation

Summary Indirect phase reflection height measurements have been performed at the Panská Ves Observatory, Czechoslovakia, for 30 years to monitor solar flare effects (SFA). Only after introducing the new receiver in May 1985, could the indirect phase height analysis (IPHA) method be applied to measurements along the Allouis — Panská Ves 162 kHJ measuring path. The IPHA method allows the electron density and pressure variability in the lower ionosphere to be studied, particularly near the 80 km altitude. This paper describes the theoretical background of the IPHA method, the measuring equipment used at Panská Ves, the method of evaluating records and checking of data, and the program package developed by us both for graphic and numerical processing, as well as our efforts to develop a homogeneous East European IPHA network. The IPHA method has been introduced succesfully at the Panská Ves Observatory.     

Determination of period of oscillation and sensitivity of simple horizontal pendulums for tidal measurements

Studia Geophysica et Geodaetica - Авторы уже раньше...     

Statistical determination of the law of dispersion of marking material in the shattered zone

Studia Geophysica et Geodaetica -     

Production of atmospheric condensation nuclei by sunrays

Summary 1) It is confirmed that in filtered, nucleus-free air, in a polyethylene balloon, if irradiated by sunglight, an immediate large number of condensation nuclei appear. — 2) The nucleus count rises to about 35. 000/cm³ and if the irradiation is continued does not increase, but decreases. This decreased is accelerated in the dark. — 3) Less intensive sunlight as when the sun was covered by clouds, gives slower and smaller increases. — 4) The same was observed if, instead of air, inducstrial oxygen or nitrogen was used. — 5) Traces of H₂S increase the sun effect enormously. — 6) Traces of NH₃ also increase it, but less than H₂S. — 7) SO₂ filtered through cottonwool gave also in the dark nuclei, which then decreased in number. — 8) It is supposed that H₂S is oxydized by the photochemical action of the sun's visible spectrum to SO₂ rc="/content/pt43q1m0vg125615/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0"> SO₃ rc="/content/pt43q1m0vg125615/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0"> SO₄ which is a nucleus. With NH₃ the formation of (NH₃)₂ SO₄ is probable. But no direct proof is given that these are the actual impurities which explain the sun's action on air. It is calculated that dilutions of 10^–15 of an impurity of the type of H₂S can quantitatively explain the sun effect. — 9) The work ofAitken is extensively quoted, who noticed, 50 years ago, the «fog produced by sun&raquo;.r>

Zusammenfassung 1) Es wird bestätigt, dass Sonnen-Bestrahlung von filtrierter kernfreier Luft, welche in einem Polyethylen-Ballon aufbewahrt ist, zum Entstehen einer hohen Zahl von Kondensations Kernen führt. — 2) Die Kernzahl steigt auf etwa 35 000/cm³. Wird die Bestrahlung fortgesetzt, dann steigt sie nicht weiter sondern nimmt ab. Die Abnahme wird im Dunkeln beschleunigt. — 3) Durch Wolken abgeschwächtes Sonnenlicht gibt eine langsamere, weniger grosse Kernbildung. — 4) Dieselben Beobachtungen wurden mit industriellem Sauerstroff und Stickstoff auch gemacht. — 5) Spuren von H₂S verstärken den Sonneneffekt enorm. — 6) Spuren von NH₃ verstärken ihn auch, jedoch weniger. — 7) SO₂ Gas, gefiltert durch Baumwollfilter giebt auch im Dunkeln schon Kerne, deren Zahl dann wieder abnimmt. — 8) Es wird angenommen, das H₂S durch photochemische Wirkung des sichtbaren Sonnenlichtes oxidiert wird zu SO₂ rc="/content/pt43q1m0vg125615/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0">SO₃rc="/content/pt43q1m0vg125615/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0"> SO₄ welch letzteres bereits als H₂HO₄ ein Kondensationskern ist. Mit NH₃)₂ SO₄ Kondensationskerne gebildet werden. Es sind jedoch keine direkten Beweise dafür vorhanden, dass diese Gase die Verunreinigungen der atmosphärischen Luft sind, welche den Sonnenffekt geben. Es wird aber berechnet, dass schon Verdünnungen von 10^–15 eine Verunreinigung H₂S den Sonnen-Effekt erklären. — 9)Aitken's Werk, der bereits vor 50 Jahren von « durch Sonne verursachten Nebel « sprach, wird gewürdigt.

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From the Clima-physiological Laboratory of St. Moritz-Bad.