Mikrofauna w osadach morskich dolnej kredy niecki brzeżnej

Abstract

MICROFAUNA IN LOWER CRETACEOUS DEPOSITS OF MARGINAL TROUGH

Summary

In the Neocomian deposits of the maxginal trough microfauna has been found. Berriasian, Valanginian and Hauterivian in age. The fauna is relatively poor. Three regions can be distinguished in the marginal trough here considered: Pomeranian though, Warsaw trough and Lublin trough. Each of them reveals slightly different micropaleontological relations which depend, to some degree, upon sedimentary environment. In the, Pomeranian though agglutinated foraminifers prevail. Two zones can be distinguished in the Upper Valanginian deposits of the Warsaw trough, depending upon microfauna abundance. In the north-western zone the Pomeranian though microfauna is poor, whereas in the south-eastern one it is considerably richer in both species and specimens. On the basis of microfauna (Protocythere pseudopropria emslandensis B a r t. et B u r r i), the author has succeded in documenting the presence of Berriasian deposits. As concerns Loweer Valanginian deposits posits no index forms have been encountered. The Upper Valanginian deposits could have been evidenced microfaunistically, mainly we to the presence of Lenticulina (Lenticulina) guttata Ten D a m, and Lenticulina (Astacolus) diversicostatus (L i s z k a). Among the Lower Hauterivian fauna no index form has been found. Both the Middle Valanginian and the Lower Hauterivian deposits reveal a very scarce marine miorofauna that distinctly points to some periodical transgressions of the sea.