Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 2. 1970-71. (Budapest, 1971)

Frag. Min. Pal. 2. 5-56. 1970-71. The Eocene-Oligocene Boundary Formations of Hungary and their Planktonic Foraminifera By Károly SZTRÁKOS Research Laboratory of Hungarian Oil & Gas Trust Budapest Introduction One of the century-old problems in Hungarian geology is the datation of the Buda Marl. Earlier it was usually assigned to the Lower Oligocène;at present it is rather considered as being of Upper Eocene age. The present paper deals with the detailed study of the planktonic Foraminifera only. The data concerning the benthonic fauna are but results of preliminary investigations, the benthonic assemblages being now under study. In 1968 I collected numerous samples of Buda Marl in the Mounts of Buda. Their study shed new light on the boundary problem. It turned out that on the basis of the foraminiferal fauna the Buda Marl is not a homogeneous formation. Later on I had the opportunity to get acquainted with samples of similar age from hydrocarbon prospecting boreholes in the southern foreland of the Bükk Mountains (NE-Hungary). The study of these confirmed the afore-mentioned conclusion. In the Mounts of Buda I studied 3 profiles: 1. Budapest XII., Sashegy Hill, Lejtő Street. All along the Lejtő Street, from Lékai Square to Hegyalja Street, a 900 m long, 2 m deep trench was dug during pipelaying