Ślady diagenetycznego syderytu w dolnym kambrze wschodniej Polski oraz znaczenie stratygraficzne tej mineralizacji

Abstract

Występowanie syderytów w postaci skupień w skałach dolnego kambru północnej i wschodniej Polski oraz Estonii w pozycji stratygraficznej równorzędnej z pozycją poziomu występowania oolitów żelazistych w tych samych utworach daje możliwość wykorzystania mineralizacji syderytowej do korelacji stratygraficznej.TRACES OF DIAGENETIC SIDERITE IN THE LOWER CAMBRIAN OF EASTERN POLAND AND STRATIGRAPHIC VALUE OF THAT MINERALIZATIONSmall lenticular accumulations of siderite and siderite-cemented intervals of siltstones were found at depths from 1265 to 1334:5 m in the Mielnik borehole column of the Radzyń Series in eastern Poland. According to chemical and x-ray-structural analyses, content of side rite cement ·in these rocks ranges from 28 to 41% (Table 1). Such occurrences may be compared with those of iron in the vergale - rausven sequence in Baltic countries of the USSR. In this way one of sections typical of eastern Poland appears very close to those from central parts of the Peribaltic Syneclize: The similarity is reflected by affinities in geological structure and general regional trends in Early Cambrian sedimentation. Under such circumstances, the studied . mineralization becomes important as stratigraphic marker for the Whole western region of the East-European Platform.In Soviet part of the Peribaltic Syneclize, siderite mineralization is relatively weakly marked but it should be noted that, similarly as in Poland (boreholes Gołdap and Bartoszyce), it is stratigraphically related to geothite oolite ores. The ores are sometimes up to 5 m thick in the former area (boreholes Talsi and Kandava). Detailed description of the types of mineralization and the nature of surrounding (parent) rocks are highly interesting.Taking into account the trends to formation of mineralization of that type in water with salinity somewhat lower than normal marine (impeded fixation of iron in glauconite and pyrite), it should be assumed that vast distribution of that mineralization reflects an important, regional event in basin at western margin of the Platform.