Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 7. 1976. (Budapest, 1976)
T. KECSKEMÉTI — A. VÖRÖS: An intra-Lutetian (Middle-Eocene) redeposited sequence at Magyarpolány (Hungary) The studied section (situated in the western part of the Bakony Mts.) crosses a series of biogenic and detrital carbonate rocks (Fig. 2). The main rock types are figured in the Plates I-VI. Special attention was paid to the poor cementation of the reoeposited middle portion of the sequence. The biostratigraphic zonation and correlation are based on a careful study of large foraminiferids, first of all, of nurnmulitids. Palaeogeographic evolution recorded in the section Drilling and outcrop data available from the neighbourhood of Magyarpolány show that after a hiatus the lowermost marine horizon of the Middle Eocene lies un conformably on the Upper Cretaceous on wide areas. The lowermost, massive, nummulite-limestone member of the section belongs to the lower part of the zone of Nummulites perforatus^ we assume that in the previous phase of the Middle Eocene marine sedimentation prevailed. During the zone of N. perforatus , however, the marine circumstances suddenly ceased. The high relief of the lowermost member showing evorsional pits can be formed only if the lithified sediment had undergone subaerial erosion and solution by turbulent water (wave action). The rapidly accumulating carbonate detritus deposited on the uneven surface marks the new transgression of the sea. The clastic material was supplied by the earlier Eocene rocks of the adjacent territories: the huge amount of reworked fossils contains the all characteristic representatives of the Lutetian biozones (zones of N. laevigatas, Assilina spira, and N. perforatus) without any observable (even inverse) vertical zonation. Moreover, the influence of a remote continental background appears in the form of many quartz and quartzite grains and pebbles of mesozoic rocks widespread in the Bakony Mts. During the deposition of the detrital sequence the environment was apparently unfavourable for life (unstable bottom, rapid sedimentation, possibly less degree of salinity). The nodular limestone composing the uppermost part of the sequence indicates an abrupt change. By the cessation of the unfavourable circumstances a rich life community could develop. The disappearence of the reworked faunal elements (= termination of redeposition 5.e. erosion) is very remarkable: the rock contains exclusively the faunal elements characteristic to the upper level of the N. perforatus zone. The section records a very short period of emersion within the Lutetian age; the eroded basement-rock represents the lower part of the N. perforatus zone while the overlying detrital complex and the nodular nummulite-limestone were deposited during the later phase of the same zone.
