Uwagi o pochodzeniu żelaza zawartego w doggerze antyklinorium śląsko-krakowskiego

Abstract

NOTES ON ORIGIN OF IRON OCCURRING IN DOOGER OF SILESIA-CRACOV ANTICLINORIUMWell-known in the Dogger deposits of the Silesia-Cracow anticlinorium are sedimentary seams of iron ores in the shape of siderites and ironstones. The iron found in these deposits is of continental origin and - as results from the palaeo-geographical conditions - must have been supplied from a southern land which separated the European epicontinental sea from the·geosynclinal Carpathian sea during the Jurassic and Cretaceous periods.While the southern part of this land consisted, during the period of the Jurassic and Cretaceous. transgression, of rocks supplying great masses of clastic material rich in quartz, the northern part was built, during the Jurassic transgression of Palaeozoic limestones and dolomites arid of rare plutonic rocks, and - during the Cretaceous transgression - of Jurassic limestones.Since there are considerable quantities of iron compounds in the transgressive Jurassic deposits; whereas they are. absent in the Cretaceous deposits, it should be concluded that the iron must be derived from Palaeozoic rocks. It is true that iron is lacking in the plutonic rocks of the Krzeszowice region; but it does occur in the form of hydrothermal pyrites which recently have been disclosed in Palaezoic deposits of the discussed region. In view of the fact that, at best, pyrites might have supplied but scanty quantities of iron, it seems justified to assume that in the Palaeozoic deposits of this region there might occur hydrothermal strata of other iron ores. This theory seems to be supported by a distinct magnetic anomaly established in the Dębnik region by J. Skorupa (1950).