Rtęć, arsen i pierwiastki grupy żelaza w utworach fliszowych kredy górnej i paleogenu łuski Bystrego koło Baligrodu

Andrzej Jaworski


Mercury, arsenic and iron group elements in the Upper Cretaceous and Paleogene flysch deposits near Baligród (Carpathians)

The results of geochemical and geothermal research work have been presented. The work has been done along profile crossing the sediments of the Upper Cretaceous and Paleogene of the Bystre scale in the eastern part of the Polish Carpathians. Bystre scale lies on the line of great tectonic dislocation separating the central Carpathian depression from the zone of Dukla folds and their foreland (Fig. 1). This narrow scaly structure (about 4 kilometres in width) with a reduced north-eastern flank and showing a reverse overturn stretches for 11 km from NNW towards SSE. It is built of Cretaceous and Paleogene deposits very strongly dislocated in different directions. Within the tectonic zones between the Lgota Beds and Upper Istebna Beds an intensive arsenic mineralization has been recorded (Kamieński 1937, Ostrowicki 1958, Ślączka 1958, Kita-Badak 1971, Gaweł 1972). The aim of the geochemical research was to find surficial phenomena of mercury-arsenic mineralization in the zone of weathering of the Istebna Beds and Hieroglyphic Beds of the Bystre scale and in the Menilite Shales and Krosno Beds thrusted over them from SW. Mercury content in the subsoil sample has been estimated with Canadian HGG-3 spectrometer, while As, Ni, V, Co, Cr, Mn, Zn, Pb, Cu, Ag and Mo concentrations have been determined by spectral method. The geothermic research has been carried out using Polish geothermometer PGS-2. The aim of the research was to localize the zone of structural discontinuities in the flysch sediments along the investigation profile (Fig. 1, 2). The results have shown that within the zones of structural discontinuities recorded by geothermic measurements an anomalous mercury content is observed '(Fig. 3). Mercury vapours most probably issue along deep pipers together with gas exhalations (Co2) or aqueous solutions. In the flysch rocks of the Bystre scale no mercury minerals have been recorded. The research on Hg content in the floral substance shows the presence of this element in the tissue of plants taken from strong dislocation zones (Fig. 3). The author also connects the anomalous concentration of arsenic found in the examined profile with these zones. Larger amounts of iron group elements and of Cu, Zn, Pb, Mo have been discovered in the zone of Lower Istebna Beds shales and standstones, Hieroglyphic Beds and above the Menilitic Shales and Krosno Beds. Statistical research of the above mentioned elements has shown a simple linear correlation between nickel, chromium and cobalt and a very strong one between copper and Co, Cr, Ni and V (Table 2) in the hypergenic zone. It has been proved that the superficial waters show small general mineralization ( < 1 g/l) and do not display any relation with the markedly mineralized intratelluric waters (Table 3). Increased content of some element from the iron group and zink in the stream waters gives support for the occurrence of unknown mineralized zones in the rocks up-stream. The above described results of preliminary geochemical and. geothermal research work justify this type of research carried out within the entire Bystre scale and its mantle. This would certainly facilitate the localization of zones of arsenic and mercury mineralization and enable the complicated tectonics of this geological unit to foe investigated in detail.

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