Siderite concretions in Paleocene series of polish part of the eastern Flysch Carpathians

The present paper deals with the results of studies of siderite concretions occurring in blackPaleocene shales of the Dukla and Silesian Units. The samples were examined using optical and scanningmicroscopy, X-ray diffraction and chemical analysis (SEM-EDS, INNA, ICP and estimation of TOC). Themain diagenetic minerals of these concretions are iron carbonates close to siderite. Less common aredolomite, ferrous dolomite and calcite. The first phases precipitated from pore solutions were carbonatesenriched in manganese. The concretions studied contain up to 49.15 wt.% Fe2O3, at most 16.46 wt.% CaOand up to 8.49 wt.% MgO, whereas the content of organic carbon (TOC) is at most 1.42 wt.%. Sideriticconcretions of Paleocene beds of the eastern part of the Flysch Carpathians represent, in fact, sideroplesitesand manganospherites of early diagenetic origin. They are, in general, impoverished in all trace elements,except Sr, when compared with shales embedding them. The siderite-bearing series in question can beassigned to the siderite-pyrite and siderite geochemical facies.