Mikrofauna malmu południowej części syneklizy perybałtyckiej

Abstract

THE MALM MICROFAUNA IN THE SOUTHERN PART OF THE PERI-BALTIC SYNECLISEFauna of foraminifera and of ostracods found in the MaIm deposits pierced by three bore holes (Pasłęk, Bartoszyce and Gołdap), made within the southern part of the Peri-Baltic syneclise,·has been elaborated. As to the individual sub-stages respective microfaunistic assemblages have been distinguished.The Oxfordian deposits are of mudstone character, the higher sub-stages revealing greater carbonate contents. Microfauna is rich and differentiated, particularly the families Lagenidae, Epistominidae and Ophthalmididae; among ostracods are found genera Pontocyprella and Krausell?The Kimmeridge deposits are marly-mudstone, clayey or arenaceous at places. The family Lagenidae is most frequently found, among ostracods are represented genera Galliaecytheridea, Macrodentina and Cytherella.In the area under study are developed the lower portions of the Portlandian, bearing arenaceous-mudstone character and lacking rich microfauna. A comparison has been made of the microfaunistic assemblages from the individual sub-stages of the Malm deposits that are developed in mudstone-marly facies in the region of Kcynia with those from the Peri-Baltic syneclise area, within the Polish territory, from the Kaliningrad region and from Lithuania. In addition, two new species have been described: Protocythere furcata n. sp. and Quinqueloculina jurassica n. sp.Palaontological description: Protocythere furcata n. sp.Test oval-rhomboidal. Ornamentation in the form of a roll-like rib bifurcating into two small ribs that meet in an arch-like manner in the dorsal part of the test. In the frontal part there is a short roll-like rib passing at the top into a semicircular auricle. The remaining area of the test covered with a fine reticulum. The hinge of merodont/entomodont type.Palaeontological description: Quinqueloculina jurassica n. sp.Test oval, in the aperture area slightly sharp, at the base rounded. Marginal edge also rounded. Chambers tubular, curved, more or less of the same breadth at the whole length. Sutures deep, distinct. Aperture round, embraced by a small lip. Tooth simple, single, sometimes slightly divided.