Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 14. 1989. (Budapest, 1989)
low sea. At around the end of the Upper Lutetian subsidence became balanced, and steady and the depth of the sea exceeded the 200 m. Its analysis has been rather difficult, since at the margin of the slowly and continuously subsiding basin the shallow marine sedimentation has always been present, as proved by the rich shelf-type fauna of N. perforatus and N. millecaput. Deep-neritic to shallow bathyal sediments were formed during the subsidence only in the internal part of the basin. Priabonian formations may be observed in some sections of the Balinka basin, e.g. in the borehole Balinka-219. The larger Foraminifera fauna of the carbonate sequence is of a shallow marine type, reflecting the depth conditions of the inner shelf region. The Upper Lutetian transgression reached the northeastern part of the Transdanubian Central Range, and through several smaller basins of the Vértes and Gerecse Mts., it got to the Dorog basin. Here not the sections characterized by carbonate sedimentation were examined, but as a specific example for the pelitic development (this differs from that in the NE Bakony Mts.), the sequences from the Pusztavám-Oroszlány region were studied. The section of seven boreholes in Oroszlány show Upper Lutetian sequences (Figs. 3-4). They begin with coal sequences, then turn into marine clayey marl and clay. The larger Foraminifera from the marine phase are especially characteristic. Generally they are of small diversity, periodicity can be observed in their vertical distribution, and commonly they reflect unfavourable conditions. The low diversity may be explained by the lack of carbonate bottom, by the looser relation with the more open marine basins (lack of currents and faunal exchange). This periodicity is caused by deepening of the sea, since the depth of the water exceeds the ecological borders of the range of the larger Foraminifera periodically, because of the uneven subsidence-another exemple for the bathymétrie significance of the larger Foraminifera. Here the water-level must have exceeded the 200 m. The impact of unfavourable environmental conditions is shown by the small shell-size, flat forms and the smooth shell. Flatness and thinness is especially apparent in Operculina (sometimes being almost translucent) and in the discocyclinids. The unfavourable conditions are also reflected by the fact that only the macrospheric forms, the products of zoogamy are present in tne sequences. There is a rather complex reason for all of these facts: the main cause in the unfavourably high water-level, but the clayey bottom, the small energy of the medium and the lack of food can all be made responsible for their production. REFERENCES BERNHARDT, B., LANTOS, M., MÁRTON, P., BÁLDI-BEKE, M., HORVÁTHKO LLÁNYI, K. and KECSKEMÉTI, T. (1985^ : Magneto- and biostratigraphy of an Eocene sequence from borehole Somlóvásárhely-1. (SW Bakony Mts, Western Hungary). - INA - Newsletter- Special Edition Vienna Meeting 1985. Proceed. Internat. Nannoplankton Assoc. , 7 (2): 53-56. DIETZ-ELBRÄCHTER , G. (1971): Untersuchungen über die Zooxanthellen der Foraminiferen Heterostegina depressa Orbigny 1826. - "Meteor" Forsch. - Ergebn., C (6): 41-47. FERMONT, W. J. J. (1977): Depth-gradients in internal parameters of Heterostegina in the Gulf of Elat. - Utrecht Micropaleont. Bull., 15: 149-163. HALLOCK, P. (1979): Trends in test shape in large, symbiont-bearing foraminifera. - Journ. Foram. Res., 9 (1): 61-69. HALLOCK, P. (1980): Application of écologie studies of living, algal symbiont-bearing foraminifera to pa leoecologic interpretation. - Amer. Assoc. Petr. Geol. Bull., 64 (5) : 716-717. HALLOCK, P. (19811 : Light dependence in Amphistegina. - Journ. Foram. Res., U (1) : 40-46. HANSEN, H.J. (19721 : Pore pseudopodia and sieve plates of A mphistegina. - Micropaleontology, 18: 223-230. HANSEN, H.J. and BUCHARDT, B. (19771: Depth distribution of Amphistegina in the Gulf of Elat, Israel. - Bull. Utrecht Micropaleont., 1_5: 205-224. HOTTINGER, L. (19771 : Foraminifères Operculiniformes. - Mém. Mus. Nat. Hist. Nat., Nouv. Sér. C, XL : 159.
