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and Ta are of low concentration and hosted mainly by Ti-oxide minerals. The Triassic Bagolyhegy Metarhyolite (BMR) of the Bükk Mts, NE Hungary, cropping out between Bükkszentkereszt and Bükkszentlászló ( Fig. 1 ), was sampled and studied by

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2001 Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth Science 293 839 843 . E

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– 634 . Daliran , F. 2002 : Kiruna-type iron oxide-apatite ores and apatitites of Bafq district, Iran, with an emphasis on the REE geochemistry of their

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253 1–2 115 140 . VP Evangelou 1995 Pyrite oxidation and its control: solution chemistry, surface

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. P.L. Blevin B.W. Chappell 1992 The role of magma sources, oxidation states, and fractionation in determining the granite metallogeny of eastern

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manganese oxide precipitation Acta Geologica Polonica 54 61 76 . Guidry , S.A. , H.S. Chafetz 2002 : Petrography and stable

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R. Kretschmar 2005 Changes in zinc speciation in field soil after contamination with zinc oxide Environmental Science and Technology 39

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/raw-materials/files/docs/crm-report-on-critical-raw-materials_en.pdf. Gross , G.A. , C.F. Gower , D.V. Lefebure 1997 : Magmatic Ti-Fe±V Oxide Deposits, in Geological Fieldwork 1997 . – British Columbia Ministry of Employment and Investment 1998/1 , pp. 24J -1– 24J -3

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This paper deals with the influence of sharp temperature variations on the geochemical fractionation and bioavailability of 241Am, 60Co and 137Cs in Fluvisol soil. The study was performed using soil contaminated with aqueous solutions of 241Am, 60Co and 137Cs in the laboratory and stored for three years at temperatures within the range of 10–18 ºC and soil moisture from 20 to 30 wt %. Afterward the soil was divided into three equal parts and conditioned for one month at 10–18 ºC, −18 ºC and 40 ºC temperature regimes, respectively. The impact of the storage conditions on geochemical forms of the radionuclides was investigated using single extraction of exchangeable 137Cs with 1 M NH4NO3 and sequential extraction of 241Am and 60Co, and by gamma-spectrometric measurement. The influence of temperature rise up to 40 ºC over a period of one month on the transfer factors (TFs) of the radionuclides from the investigated soil to orchard grass (Dactylis glomerata L.) was evaluated. The results showed that deep freezing and a sharp temperature increase continuing for one month led to re-distribution of 241Amand 60Co between the soil phases and provoked an increase of the exchangeable 137Cs. Freezing led to a decrease of 241Am in the residual fraction and an increase of oxide-bound americium. The storage at frozen conditions led to decrease of oxide bounded 60Co and increased immobilization in the residual fraction. Conditioning at high temperature increased the migration ability of 241Amand 137Cs, while immobilization of 60Co was registered. Conditioning at a sharp temperature increase before the growing season led to higher values of the TFs of all the studied radionuclides. This effect was highest for 137Cs. The sharp temperature change of contaminated Fluvisol soil lasting one month was found to create a risk of increased migration and bioaccumulation of radionuclides.

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A partially molten buchite xenolith containing quartz, glass, mullite/sillimanite, corundum, Al-rich orthopyroxene, spinel, Mg-Al-bearing Fe-Ti oxides, ilmenite and rutile was found in the basaltic tuff of Szigliget (Balaton Highlands, Hungary). The pre-existing rock may have been a quartz-rich micaschist or phyllite from the wall of the magma vent. Minerals like mullite, Al-mullite and Al-rich orthopyroxene with Al2O3 between 7.62 to 11.54 wt% show ultrahigh-temperature (UHT) metamorphism of the xenolith with temperatures in excess of 1080 °C, which means that the temperature of metamorphism approached that of the enclosing alkaline basaltic melt. CO2 fluid inclusions with homogenization temperatures between +26.5 and +29.7 °C and mineral equilibria indicate pressure of buchitization between 310 and 390 MPa.  Glass compositions are similar to a peraluminous leucogranite which is in accordance with melting experiments when metagreywackes, pelites and orthogneisses are involved. The presence of glass suggests that the duration of the heating process was not long enough to extract the melt from the rock and admix it with the alkaline basaltic melt.  

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