Mikrofauna utworów liasu z profilu wiercenia Świnoujscie 1

Iwona Rek




In the borehole profile Świnoujście (Fig. 1) Liassic sediments have been found at a depth between 497.0 and 1055.0 m. Nine samples have been taken from the cored parts (Table 1), out of which seven have yielded a very rich and excellently preserved micropaleontological  assemblage indicating the Carixian-Domerian age.
Within the Polish territory, Liassic sedimentation occurred in a fresh-water basin (Fig. 1). These areas were invaded by the sea only from the NW through the Kujavian-Pomeranian furrow. During the Carixian and the Domerian this region must have communicated both with the sea of northern and western Europe as well as with the Alpine geosyncline. This is reasonably suggested by the presence in the profile here considered of numerous  Foniminifera species; which occur in those areas too.
The sea was shallow and off-shore as is indicated by the occurrence of megaspores, plant fossils and a fair abundance of OphthaImidiuam (a genus reported from shallow seas). Diagrams in Figs 2 and 3 show the percent content changes in the vertical section of the more interesting microfossil groups. These lead to suppositions (of minor importance) concerning changes in the sea depths and in the coastline in that part of the basin here under consideration. Increased numbers of foraminifers from the family Nodosariidae suggest increasing depth while greater number of agglutinated foraminifers suggest sea shallowing. An increase in the numbers of megaspores and plant remains suggests an approach to the coastline.

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