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Average concentrations of Pb, Zn, Cu, and other metals, as well as S and As, were calculated for the Aue granitic cupola,
the contact aureole of which hosts the large vein-type uranium deposit of Schlema-Alberoda and the Schneeberg uranium-base
metal deposit (Erzgebirge, Germany). The cupola was exposed by mine workings and boreholes, which provided an opportunity
to evaluate variations in the abundances of metals in the granites over a vertical interval of more than 2.5 km and estimate
their losses in the upper oxidized part of the investigated volume of the cupola (coefficient of iron oxidation, KO
Fe, increases in the granites from bottom to top from 7 to 70%) compared with the lower unaltered and unoxidized part (with
a KO
Fe plateau at about 5%). The average concentrations of metals in the upper part of the cupola are lower than those in the lower
part by a factor of 2.5 for Pb, 1.56 for Zn, 1.45 for Cu, 1.3 for Co, etc. A similar decrease in the abundances of ore elements
along the vertical section associating with the relative epigenetic alteration and oxidation of the granite was previously
described by us for U and Th and for the components of high-temperature ores, W, Sn, and Mo. The removal of ore elements from
the granite was accompanied by a decrease in the bulk contents of sulfur and arsenic by a factor of 1.35 and 1.65, respectively.
The leaching of trace metals from the granites of the upper part of the Aue cupola was followed by their partial redeposition
above the cupola in the ore veins of the Schlema and Schneeberg deposits.
Original Russian Text ? Vikt. L. Barsukov, N.T. Sokolova, O.M. Ivanitskii, 2006, published in Geokhimiya, 2006, No. 9, pp.
967–982. 相似文献
2.
Geochemical,mineralogical and magnetic characteristics of vertical dust deposition in urban environment 总被引：1，自引：0，他引：1
Péter Sipos Emő Márton Zoltán May Tibor Németh Viktória Kovács Kis 《Environmental Earth Sciences》2014,72(3):905-914
Studies on composition and distribution of dust deposition are necessary for the risk assessment of dust to atmospheric quality. We studied the vertical distribution pattern of dust and metal (Cu, Fe, Pb, Zn) deposition up to 33 m height in urban environment. Integrated geochemical, mineralogical and magnetic study of the seasonally sampled dust helped to specify our knowledge on the use of magnetic susceptibility for tracking its deposition. Harmful dust and metal deposition may occur even at great heights and at the low-traffic side of buildings. Re-suspension of local surface materials dominates the dust deposition primarily in summer and spring due to weather conditions, and it may overwrite the influence of recent anthropogenic activities on dust composition. The accepted air-flow models should be modified by taking the local conditions (weather, morphology, etc.) into account. All studied metals showed strong enrichment in the dust and could be characterized by similar vertical deposition pattern to dust. The total susceptibility was found to be much more useful proxy for tracking dust and metal deposition than mass-specific susceptibility. Using the former, potential errors arising from sampling practice of settled dust could be eliminated. The most important heavy-metal-bearing phases were iron oxides and clay minerals. Their different behavior during the dust deposition is reflected by the vertical metal distribution patterns. Clay minerals originate primarily from re-suspension and may be one of the most important sources of potentially mobile heavy metals in such materials. 相似文献
3.
Vikt. L. Barsukov 《Geochemistry International》2006,44(6):591-612
The geochemical events that occurred within the outlines of the Schlema ore field during the formation of vein bodies cannot be understood without considering the processes that occurred synchronously in the footwall zone, in the Aue granite cupola, from where mineral-forming thermal solutions ascended into the deposit. It is known that the upper part of the cupola experienced hydrothermal alterations, which had a minor influence on the appearance of the rocks, but caused a number of important geochemical consequences: an increase in the degree of iron and sulfur oxidation in grantie, the replacement of accessory sulfides by oxygenbearing salts, etc. These changes were analyzed using computer models for a decrease in T and P of the granitewater system from 400°C (3.0–1.5 kbar) to 140°C (2.0–0.2 kbar). The role of these changes in the fate of disseminated ore elements of granite and in the extraction of ore elements from the changing rock into the equilibrium pore solution was evaluated. 相似文献
4.
Vikt. L. Barsukov 《Geochemistry International》2006,44(12):1191-1214
By means of computer modeling, it was shown that the pre-uranium quartz and quartz-sulfide veins of the Schlema deposit with
their typomorphic assemblages could be formed at the expense of cooling of hot pore solutions from the Aue granite cupola
underlying the mineralized zones. As was shown previously [1], the ore metal content of these pore solutions changes with
decreasing temperature and pressure in the granite-water system and an increase in the intensity of granite “flushing” with
a water phase. The dependence of the composition of precipitated material on the proportions of chlorides and carbon dioxide
in the pore solutions was evaluated in the models. It was shown that silica mobilization from the granite and redeposition
were accompanied by the oxidation of ferrous iron in the granite and extraction of sulfide sulfur in molal amounts similar
to or even higher than those of silica. This provided conditions for uranium migration after these stages and formation of
hydrothermal uranium ores.
Original Russian Text ? Vikt.L. Barsukov. 2006, published in Geokhimiya, 2006, No. 12, pp. 1290–1314. 相似文献
5.
Péter árkai Isabel Abad Fernando Nieto Tibor Németh Péter Horváth Viktória K. Kis Katalin Judik Juan Jiménez-Millán 《Swiss Journal of Geoscience》2012,105(2):263-282
Frequently, at temperatures lower than the metamorphic peak conditions, slates undergo mineral transformations, usually mediated by fluids. We have studied core material of an epizonal slate series (Szendr? Mountains, NE-Hungary) to reconstruct the post-metamorphic lower-T hydrothermal alterations using petrographic, X-ray diffraction, electron microprobe methods, and transmission electron microscopy. The borehole crosscuts an upper part of the ca. 600?C800?m Lower-Carboniferous flysch-like Szendr? Phyllite Formation. The samples were metamorphosed reaching epizonal conditions with a mineral assemblage characterized by quartz, muscovite, chlorite and albite. Even in the freshest samples, break-up and loosening of the regional metamorphic structure was observed, with cracks parallel to or crossing the cleavage. In the upper part, chlorite and albite are almost absent, while the presence of paragonite, mixed Na?CK mica, and mixed-layered minerals with smectitic component are characteristic. Goethite, halloysite, and subordinate kaolinite are present in the most altered sample (13.0?m in the profile) which may indicate the position of the fissures in which the circulation of the post-metamorphic fluids was the most intense. Muscovite is the only mica from the lower part of the profile and chlorite becomes a significant constituent, whereas paragonite, halloysite, and kaolinite are missing. Discrete smectite is present in all the samples in spite of being incompatible with the prograde evolution of the sequence. The interleaved smectite layers in chlorite and muscovite/chlorite mixed-layers show at the lattice level textural characteristics indicative of a later alteration process. After the metamorphic peak at epizonal conditions, the introduction of hot fluids through the fractures gave rise to the crystallization of Na?CK white micas and muscovite/chlorite under anchizonal conditions. In a final stage of the hydrothermal process, the cooling of the circulating fluids favored the formation of halloysite and kaolinite in the areas near to the fissures, smectites in the samples far away from the fractures, and locally, goethite. The Fe2O3 content increasing upwards indicates oxidizing conditions in the late stage of hydrothermal activity and/or eventually, an influence of a younger near-surface weathering. 相似文献
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