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Wyszukujesz frazę "rare elements" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Lithologically-related rare earth element variations the Mio-Pliocene Poznań Formation (Poland)
Autorzy:
Retka, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059369.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Poznań Formation
rare earth elements
clay lithotypes
Opis:
Concentrations of rare earth elements (REEs) were determined in 129 clay samples collected from the Mio-Pliocene Poznań Formation in Poland. The REEs occur in a relatively wide range from 58.2 to 1,709 mg/kg. Low North American Shale Composite (NASC)-normalized total REE contents with heavy rare earth element (HREE) depletion were noted in most of the samples analysed. Small variations were detected in the REE contents in the lithologies distinguished. Red clays are characterised by slightly lower REE concentrations relative to green and grey clays. All the Poznań Formation clays exhibit a negative Eu anomaly when normalized to the average of chondrites. Values increase according to the following sequence: grey clays < red clays < green clays. The NASC-normalized REE concentration curves show a positive Eu anomaly. The LaNASC/YbNASC ratio indicates HREE depletion. A small variation in this ratio was observed in the sequence green clays > grey clays > red clays. The variability of the REE contents of the Poznań Formation decreased from west to east.
Źródło:
Geological Quarterly; 2018, 62, 1; 146--154
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controls on the distribution of rare earth elements in the Kupferschiefer series of SW Poland
Autorzy:
Oszczepalski, S.
Chmielewski, A.
Mikulski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2060523.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
rare earth elements (REE)
redistribution
Kupferschiefer
Zechstein
SW Poland
Opis:
This study deals with the spatial distribution and the PAAS-normalized patterns of rare earth elements (REE) studied by ICP-MS in the Kupferschiefer series of SW Poland. The most characteristic feature is a progressive enrichment in REE content (including Y and Sc) outward from the rocks with pyritic and Pb-Zn mineralisation, across the rocks with copper mineralisation, towards the oxidized (Rote Fäule) areas. The same trend can also be observed with respect to LREE, MREE and HREE. Whereas REE distribution diagrams for shales with pyrite and Pb-Zn mineralisation are almost flat, diagrams for shales with hematite and copper mineralisation are convex-upward and the strongest convexity is attributed to the transition from hematitic alteration to copper-rich rocks. REE distribution diagrams normalized to PAAS show strong MREE enrichment relative to LREE and HREE, which is typically the highest in the hematite zone, lower in shale with copper mineralisation, and the lowest in shales with Pb-Zn and pyrite mineralisation. The systematic increase in the concentration of REE towards the Rote Fäule, and the strong enrichment in MREE in the transition zone are indicative of variable intensity of leaching and formation of the REE enrichments (including MREE) by MREE>HREE>LREE fluids, as evidenced by the MREE-enriched signatures. Overprinting of secondary enrichments over the original REE pattern due to redistribution along the pathways of expanding fluids are postulated to account for the apparent differences in the distribution and concentration of REE (including the MREE-enriched trend) between the oxidized rocks, copper-bearing rocks, and reduced lithologies barren in copper.
Źródło:
Geological Quarterly; 2016, 60, 4; 811--826
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The stability of xenotime in high Ca and Ca-Na systems, under experimental conditions of 250–350°C and 200–400 MPa : the implications for fluid-mediated low-temperature processes in granitic rocks
Autorzy:
Budzyń, B.
Kozub-Budzyń, G. A.
Powiązania:
https://bibliotekanauki.pl/articles/2060298.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
xenotime
yttrium fluorapatite
yttrium silicate
rare earth elements (REE)
experimental petrology
Opis:
he stability of xenotime was tested by experiments in the presence of a silicate mineral assemblage and two different fluids, 2M Ca(OH)2 or Na2Si2O5 + H2O, under P-T conditions of 200-400 MPa and 250-350°C. The xenotime was stable in runs with 2M Ca(OH)2, replicating the low-temperature metasomatic alterations of granitic rocks, except in experiment at 350°C and 400 MPa, where some (Y,REE)-rich fluorapatite formed. Experiments with Na2Si2O5 + H2O resulted in significant xenotime alteration and partial replacement by an unknown (Y,HREE)-rich silicate, and in the formation of minor amounts of (Y,REE)-rich fluorapatite. The latter indicate preferential partitioning of Y and REE into silicates over phosphates during low-temperature, metasomatic processes in a high Na-Ca system, similar to peralkaline granitic rocks.
Źródło:
Geological Quarterly; 2015, 59, 2; 316-324
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical and morphological characterization of polymetallic (Mn-Fe) nodules from the Clarion-Clipperton Zone in the Pacific Ocean
Autorzy:
Kozłowska-Roman, Agata
Mikulski, Stanisław
Powiązania:
https://bibliotekanauki.pl/articles/2058694.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
polymetallic nodules
critical elements
rare earth elements
deep-sea mining
Clarion-Clipperton Fracture Zone
Pacific
Opis:
Geochemical studies (WD-XRF, ICP-MS, and GF-AAS) have shown that polymetallic nodules from the eastern Clarion-Clipperton Zone (CCZ) in the Pacific Ocean are enriched in several metals such as Cu (mean 1.16%), Ni (1.15%), Co (0.15%), and Zn (0.14%), as well as remarkable contents of Mo (0.059%), V (0.04%), Ce (0.019%), Nd (0.011%), Li (0.015), and Pt (43 ppb). The average content of REE, together with Y and Sc, is 620 ppm. In nodules from the CCZ metal concentrations are often much higher than those reported in nodules from other ocean basins in the world. The bulk-nodule mean value of the Mn/Fe ratio is 5.3, which is characteristic for a mixed (hydrogenetic and diagenetic) origin of the nodules. Microprobe investigation revealed two different chemical compositions of the layers, and ascertained their general metal content. The nodules analyzed are composed mainly of concentric-collomorphic laminae of Mn and Fe (oxy)hydroxides which crystallized around mineral nuclei (e.g., quartz, clay minerals), bioclasts or rock fragments. They are from 3.3 to 7.6 cm in diameter. The chemical and physical properties of the laminae allowed distinction of two genetic types: hydrogenetic and diagenetic. Those formed as a result of hydrogenesis had increased values of Co, Si, Cl and S, while formed diagenetically showed increased levels of Cu, Ni, Mg, Zn and K. These lamina types are characterized by different growth structures, reflectivity, density and Mn/Fe ratios. The ratio of the diagenetic layers to hydrogenetic layers (192/53) in representative polymetallic nodules shows that the nodules of this study are of mixed hydrogenetic-diagenetic type. A mixed genesis was also shown by discriminant diagrams, with these CCZ samples being located at the transition between typical hydrogenetic and diagenetic fields.
Źródło:
Geological Quarterly; 2021, 65, 4; 177--194
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rare earth elements distribution in fine-grained deposits from the uppermost Triassic and Lower Jurassic of the Polish Basin : provenance and weathering of source area
Autorzy:
Brański, P.
Mikulski, S. Z.
Powiązania:
https://bibliotekanauki.pl/articles/2059878.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
rare earth elements (REE)
provenance
palaeoweathering
uppermost Triassic
Lower Jurassic
Polish Basin
Opis:
Nineteen samples of uppermost Triassic and Lower Jurassic claystones and mudstones, which were formed in the epicontinental Polish Basin, were analysed by inductively coupled plasma mass spectrometry (ICP-MS) for rare earth elements (REE) and other selected trace elements (Sc, Y, Th, Zr and U). The results indicate that the source of most of the claystones and mudstones studied were sedimentary rocks of the upper continental crust of old cratonic areas, where the protolith had a mainly felsic character. However, in the latest Triassic a characteristic layer formed, implying significant input from mafic volcanic protolith. It was also found that moderately intense chemical weathering usually favoured increased concentration of the rare earths. Extremely strong hydrolysis, related to episodes of very hot and humid climate (greenhouse events), caused conspicuous impoverishment in REE in residual clays. Weathering and recycling processes modified the composition of REE to some extent, but generally did not obliterate the original characteristics of the protolith. In some samples, enrichment in rare earth elements was observed, caused by admixtures of accessory minerals (being a main carrier of REE) and/or increased sorting during recycling.
Źródło:
Geological Quarterly; 2016, 60, 2; 441--450
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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