Sapropelit z profilu otworu wiertniczego Dzikowiec IG 1 (depresja śródsudecka)

Grzegorz J. Nowak



The Dzikowiec IG 1 borehole was located in the Nowa Ruda area of the Lower Silesian Coal Basin (south-eastern part of the Intrasudetic Basin). In the studied borehole section were found, the coal-bearing deposits of the lower part of the Wałbrzych Beds (Namurian A). These sediments consist of sandstones, conglomerates and carbonaceous shales with coal seams. The sapropelic coal bed occurs at the top of the humic coal seam of greatest thickness. The sapropelite is black and dull. It is very homogenous, compact and cracks with conchoidal fracture. The microscopic investigations show it is composed of vitrinite (desmocolIinite, vitrodetrinite), exinite (mainly of sporinite seldom liptodetrinite), intertinite (intertodetrinite, fusinite + semifusinite). The sapropelite does not contain alginite. The sapropelic coal is very rich in spores. The inorganic constituents of coal are small euhedra and framboids of pyrite, clay minerals, carbonates and quartz. Under the microscope this coal shows typical features for sapropelite i.e. microstratification and fine size of particular components. The petrographic features this rock could be termed as spore cannel. Some significant conclusions can be drawn from abundant pyrite euhedra and framboids occurrence throughout the sapropelite. These pyrite bodies indicate syngenetic formation by anaerobic, suIfate – reducing bacteria. Regarding such reducing environment as a source of ferrous iron, such bacteria are most active at pH 6.5 to 8. Thus, the occurrence of syngenetic pyrite in the cannel suggests a neutral to alkaline chemical milieu in which organic materials could accumulate. Relatively low vitrinite content could refered partly to enhanced microbial degradation of lignocellulose in non-acidic setting. The petrography of the cannel clearly indicates that the deposit was formed mainly due allochthonous accumulation of plant material. The spore character of the cannel and its other features (i.e. Iow content of vitrinite) suggests that this deposit originated in shallow - water basin of neutral chemistry

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