Wyniki badań geochemicznych i mineralogicznych uranu w cechsztyńskich utworach miedzionośnych Lubin-Polkowice

Abstract

W opracowaniu przedstawiono wyniki badań geochemicznych i mineralogicznych w cechsztyńskich utworach miedzionośnych·na obszarze Lubin-Polkowice. Stwierdzono, że poszczególne odmiany litofacjalne tych utworów charakteryzują się zróżnicowaniem koncentracji uranu. Badania mineralogiczne pozwoliły na określenie minerałów uranu, smółki uranowej związanej z karburanami oraz schröckingerytu.

RESULTS OF GEOCHMICAL AND MINERALOGICAL STUDIES ON URANIUM IN ZECHSTEIN COPPER-BEARING STRATA FROM LUBLIN – POLKOWICE AREA

The paper presents the results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from the Lubin-Polkowice area. It was found that particular lithofacial varietes of Zechstein copper-bearing strata are characterized by different concentration of uranium. The mineralogical studies made possible determination of the nature of uranium mineralization and the interdependence between uranium and lithology of copper-bearing strata.

1. An interesting uranium mineralization was found in tectonic breccias which yield black blende and schröckingerite as well as calcite, gypsum, pyrite, hematite and goethite secondary minerals such as schröckingerite and goethite evidence intense weathering processes acting in the copper deposit.

2. The highest value of geochemical background of uranium in the copper-bearing series is displayed by basel copper-bearing shales (so called pitch-black shales) - 68.10 • 10^-4% U. Statistical distribution of that element is unimodal.

3. Distribution of uranium is polymodal in basal sandstones of the copper-bearing series. The geochemical background of red-coloured sandstones (Rotliegendes) is low, equaling 0.39 • 10^-4% U, whilst that of gray-coloured·sandstones (Zechstein) - 2.32• 10^-4% U. A anomallous population (344.0 • 10^-4% U) found in the case ·of gray sandstones of the Lubin-Polkowice area evidences the effects of secondary processes on concentration of uranium. In sandstones occur black blende, carburanes as well as calcite; hematite and goethite.

4. A bimodal distribution of uranium was found in carbonate series. Limestones are·characterized by low values of geochemical background (D_x1 = 0.78• 10^-4% U) whilst dolomites by markedly higher values of the background (D_x2 = 2. • 10^-4% U).