Osady górnej kredy południowej części niecki łódzkiej w świetle badań mikropaleontologicznych (Komunikat wstępny)

Abstract

Na podstawie otwornic opracowano stratygrafię osadów górnej kredy w południowej części niecki łódzkiej. Zbadany materiał otwornicowy pozwolił na wydzielenie czterech pięter w osadach górnej kredy i zmianę granic podkenozoicznych wychodni. SOME PRELIMINARY MICROPALEONTOLOGICAL OBSERVATIONS ON THE UPPER CRETACEOUS DEPOSITS OF THE SOUTHERN PART OF THE LÓDŹ TROUGH (preliminary notice)The Upper Cretaceous deposits were investigated for the preparing the Geological Map of Poland (scale 1:50 000). Stratigraphy of these deposits was established on the basis of foraminiferal material from the boreholes located within the southern part of the Lódź Trough (Fig. 1). All the boreholes in mesozoic were full cored but the lengh of them was less than 10 meters. The Upper Cretaceous deposits are represented by marls, marly limestones, sandy marls un chalk. They contain representatives of the following genera: Neoflabellina, Bolivina, Bolivinoides, Globotruncana, Eponides, Cibicides, Globorotalites, Stensioeina, Gavelinella, Cibicidoides and others. Foraminifers were examined and the relative age of the deposits was estabilished. The results could be compared with those presented by E. Gawor-Biedowa (1965, 1972, 1978, 1980), I. Heller (1975), K. Pożaryska (1965), W. Koch (1977). It is possible to distinguish Coniacian, Santonian, Campanian and Maestrichtian stage (Tab. 1) and change the boundary of their outcrops under the Cenozoic deposits. The main changes are connected with the Maestrichtian stage. The presence of this stage has been proved at Łask sheet with no doubt but the boundary had to be changed in comparison with the other maps. The investigation will be continued on the abutting sheet while mapping.