Minerały ilaste triasu górnego okolic Kluczborka

Abstract

W artykule przedstawiono wyniki badań rentgenostrukturalnych i derywatograficznych minerałów ilastych z utworów triasu górnego monokliny śląsko-krakowskiej. W osadach kajpru występują zespoły: chloryt, illit i illit-smektyt oraz illit, chloryt i illit-smektyt, natomiast w osadach retyku zespoły: illit-smektyt, chloryt i illit oraz illit, kaolinit, illit-smektyt i ślady chlorytu. Zawartość chlorytu wzrasta ku osadom starszym, zaś kaolinitu, występującego tylko w utworach bezwapiennych, ku osadom młodszym.CLAY MINERALS IN THE UPPER TRIASSIC SEDIMENTS IN ENVIRONS OF KLUCZBORKThe mineral composition of the clay fractions of the Upper Triassic sediments, which are under exploitation in the environs of Kluczbork, the Silesia-Kraków monocline, has been analysed by X-ray and DTA methods. They are composed mostly of the following clay minerals: illite, irregularly interstratified minerals of the illite-smectite series and chlorite. Kaolinite is usually lacking. It appears only in the limeless sediments of the Rhaetic.In the Keuper, two different assemblages of clay minerals are present: chlorite, illite, irregularly interstratified illite-smectite and illite, chlorite irregularly interstratified illite-smectite. They differ from the assemblage comprising kaolinite, illite, irregularly interstratified illite-smectite and traces of chlorite, which is characteristic for the Middle Triassic sediments.In the Lower Rhaetic, irregularly interstratified illite-smectite prevails over ,chlorite and illite. The Middle Rhaetic sediments yield illite, irregularly interstratified illite-smectite, chlorite and kaolinite. The mineral ratios are changed again in the uppermost Rhaetic sediments yielding the following series: illite, kaolinite, irregularly interstratified illite-smectite and traces of chlorite.Chlorite is represented by clinochlore-like clay mineral and its content increases along with the age of the layers. Illite has a clearly dioctahedral disordered structure and may be classified as Md polytype. It is associated by the swelling-faze of the various content, from 20 volume per cent in the old layers, up to about 90 volume per cent in the youngest layers of the Triassic. The minor constituents of the clay fractions in the Triassic sediments are the following accessory minerals: quartz, calcite, dolomite and anatase.