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2 2007

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Surowce ilaste ceramiki budowlanej w dawnych ośrodkach wydobycia rud żelaza

Szczepańska M., Witkowska M.

WUG : bezpieczeństwo pracy i ochrona środowiska w górnictwie

2007

nr 6

58-59

Przy eksploatacji dawnych złóż rud żelaza monokliny śląsko-krakowskiej oraz zewnętrznych Karpat fliszowych skały ilaste stanowiły materiał odpadowy. Obecnie skały ilaste są wydobywane jako ważny surowiec dla ceramiki budowlanej. Syderyty, stanowiące niegdyś rudy żelaza, są składnikiem niepożądanym przy eksploatacji iłów. Zwrócono uwagę na brak aktualnych możliwości wykorzystania syderytów oraz na fakt, że ich wietrzenie na hałdach stanowi niebezpieczeństwo dla środowiska naturalnego.

At exploitation of ancient ironores deposits from Cracow-Silesia upland and Flysch Carpathians, clays were not utilized. Actually they are the main source of building ceramics raw materials. The siderites, being formerly ironores are waste material at exploitation of clay deposits. The authors point out for lack of possibilities to utilize siderites and for the fact that their weathering on dumps is dangerous for natural environment.

Origin of siderites from the Lower Jurassic Ciechocinek Formation from SW Poland

Leonowicz P.

Geological Quarterly

2007

Vol. 51, No 1

67-78

Sideritic rocks, which are characteristic constituents of muddy-silty deposits of the Lower Jurassic Ciechocinek Formation, occur commonly as layers, lenses and small irregular concretions composed of siderite mudstone and siltstone as well as less common lenses of sideritic sandstones. Three types of siderite cement were observed in thin sections: fine-crystalline variety (SF), coarse-crystalline rhombohedra (SR) and fine-crystalline biogenic aggre gates (SA). In all these types BSE analysis revealed compositional zonation of crystals, with in ternal parts enriched in Mg, Mn and Ca and outer zones almost pure siderite. d13C values and chemical composition of siderites combined with the presence of early diagenetic pyrite indicate that siderite crystallized from brackish marine-derived solutions; only in the case of two samples from the lower part of the Ciechocinek Formation the fresh water origin cannotbe excluded. Mn and Fe were supplied by rivers and released by Fe- and Mn-reduction in suboxic zone, whereas Mg and Ca were derived from sea water, which infiltrated into the sediment. Crystal zonation resulted from the diagenetic evolution of pore water as the sediment was buried. Similar composition and development of siderite crystals from different parts of one layer indicate that siderite precipitated simultaneously throughout the whole horizon. Precipitation began from the formation of numerous nuclei and continued by growth of crystals onto them. It could begin already in the iron reduction subzone and continued in the sulphate reduction and methanogenesis zones.