Kalcytowe pseudomorfozy po siarczanach z warstw terebratulowych

Abstract

CALCITIC PSEUDOMORPHS AFTER SULPHATES FROM THE TEREBRATULA BEDS (MIDDLE TRIASSIC, UPPER SILESIA, SOUTHERN POLAND) Summary Calcitic pseudomorphs after sulphate minerals (Figs. 2, 3) have been found in the vicinity of Dziewkowice and Góra św. Anny (Upper Silesia, Poland), in the Terebratula Beds (Fig. 1) deposited during maximum flood of the Lower Muschelkalk transgression. The close relation between pseudomorphs and Thalassinoides burrows, as well as their co-occurrence with pyrite, can be explained as the effect of bacterial activity during early diagenesis: - storm deposition of allochthonous coquina layer, - decomposition of soft tissue of buried animals by aerobic bacteria: crystallization of sulphate minerals, - decomposition of sulphates in anaerobic conditions, - in situ replacement of sulphates by calcium carbonate, i. e. origin of pseudomorphs - crystallization of pyrite.