PSTRE UTWORY TYPU BREKCJI ZAWALOWEJ Z KOPALNI WE.GLA KAMIENNEGO ,,MARCEL' (GORNOSL4SKIE ZAGL^BIE W^GLOWE)

摘要

In the "Marcel" Coal Mine a collapse breccia was found in a cross-cut at the 300 m level in 2001. The breccia occurs within red beds, in a zone where the seam No. 505 has a reduced thickness. With regard to an exceptionally diversified mineral composition that results from a complex origin of this rock, it was studied using optical microscopy as well as the XRD, IR and SEM/EDS methods. Neogenic components of the breccia are represented mainly by Mg-Fe-montmorillonites, halloysite-7 A and -10 A, harrnotome, hematite, siderite and cristobalite. Additional minerals identified include mullite, goethite, mixed-layer illite/smectite, kaolinite-T, alunite, chalcopyrite and sphalerite. They are accompanied by usually numerous quartz epiclasts and traces of organic matter. The breccia consists of fragments of hanging wall rocks, mainly Carboniferous claystones and mudstones and their minerals, thermally altered and, then, metasornatically bound with scarce cement. The rock was formed by filling an empty space left after partly burned out bituminous coal, self-ignited as a result of pre-Miocene weathering. The metasomatic processes and cementation took place in the environment with gradually changing conditions, from strongly acidic and oxidizing to alkaline and reducing.