Uran w Polsce – historia poszukiwań i perspektywy odkrycia złóż

Abstract

Uranium in Poland – history of prospecting and chances for finding new deposits.A b s t r a c t. The plans for development of nuclear energy to cover Poland's needs for power raise the question of perspective domestic uranium resources. Prospecting for uranium deposits has been carried out with varying intensity since the end of the 1940s until the 1990s. In the early 1960s these works resultedin discovery of several uranium deposits and occurrences in the Sudetes. Outside of that region, uranium was also found and extracted from the Staszic piryte deposit in Rudki, the Holy Cross Mountains. Total production of uranium in these times in Poland is estimated at about 650 t. A new phase of prospecting was initiated by the Polish Geological Institute in 1956, resulting in discoveries of uranium mineralization in the Ordovician Dictyonema Shales in the Podlasie Depression and the Lower and Middle Triassic sediments in the Peribaltic Syneclise. Moreover, the so-called parallel studies, based on all the available geological and geophysical borehole data from the whole area of Poland, made it possible to analyze distribution of uranium in practically all geological units and formations in the country, especially in the Oligocene Menillite Shales of the Carpathians, the Carboniferous of the Upper Silesian Coal Basin, Zechstein copper-bearing shale and phosphates. The performed analyses, including large-scale geological works aimed at identifying uranium concentrations in the Dictyonema Shale of the Podlasie Depression, Triassic rocks of the Peribaltic Syneclise and Permo-Carboniferous rocks of the Intra-Sudetic Depression, gave us sufficient knowledge for evaluation of possible occurrences of uranium deposits in Poland. Based on our reanalysis of all available data, it may be stated that the Sudetic deposits are of historical importance only. The uranium concentrations known from Upper Carboniferous and Lower Permian rocks (Grzmiąca,Wambierzyce and Okrzeszyn deposits and mineralization shows found in adjacent areas) should be treated as areas with anomalous uranium contents but, unfortunately, without any greater economic significance due to low uranium content, low resources and often observed strong association of uranium with organic matter. The Rajsk deposit and uranium concentrations in the Dictyonema Shale formations (Podlasie Depression) are characterized by low grade uranium mineralization and occurrence at depths of over 400mand, therefore, can not be considered as a potential source of uranium. The Triassic rocks of Peribaltic Syneclise represent a possible uranium deposit of the sandstone type. However, because of large depth of occurrence (over 800 m), usually very high variability in uranium content and location mainly in areas under legal protectiont, these resources should be hypothetical, that is requiring further studies. It may be stated that the degree of recognition of radioactivity of individual geological formations and structures minimizes chances for discovery of any deposits of industrial importance.