Skamieniałości śladowe w ordowiku strefy Koszalin–Chojnice — nowe dane

Abstract

Trace fossils in the Ordovician of the Koszalin–Chojnice area (NW Poland) — new data.S u m m a r y: A moderately rich trace fossil assemblage in the Ordovician rocks of the Koszalin–Chojnice area (NW Poland) has been recovered for the first time. Previously the only evidence of trace fossils was represented by the clusters of small cylindrical pellets assigned to the Tomaculum problematicum (Groom). The newly discovered trace fossils occur in greyish-brown and greyish-green claystone and silty claystone of Llanvirnian to Lower Caradocian (teretiusculus — multidens zones). The most diverse and well-preserved trace fossils have been found in the Skibno 1 profile. They are known also from the other deep boreholes: Jamno IG 2, Miastko 1, Polskie Łąki IG 1 and Chojnice 5. The ichnofossil association is represented mainly by fodinichnia of the deposit feeders: Planolites isp. and Chondrites isp. In the multidens zone of the Skibno 1 profile, domichnia of suspension feeders: ? Cylindrichnus isp., ? Bergaueria isp. and Palaeophycus isp. appear. Ordovician ichnofossils from deep boreholes of the Koszalin–Chojnice area differ from the Nereites ichnofacies which has been identified on the Rügen Island (Germany). The intervals with trace fossils define the levels of better oxygenation and the presence of domichnia of suspension feeders in the upper part of the Lower Caradocian — a new feeding resources in a more agitated and probably shallower environment.