Field trip guidebook (dedikált példány) [antikvár]

Annali Universitä di Ferrara Sei. Terra V. 8 Suppl. 2000 Two types of Eocene can be found in Hungary: an epicontinental and a flyschoid one. The second (as a part of the so-called Magura Flysch) is known only from boreholes below the Great Hungarian Plain, beginning from NW Romania (the Maramures district) and stretching to the SW until Szolnok at the river of Tisza. More details on this so-called Szolnok-Maramures flysch trough can be found in Nagymarosy & Báldi-Beke (1993). The epicontinental Eocene is far better known because it is well outcropped, contains and/or overlies important mineral deposits (bauxite, brown coal, manganese ore), represents the whole Middle and Upper Eocene (an about 15 million years time span) mainly in carbonate facies and because its larger foraminiferal fauna is a classical Tethyan one. It is described in detail by Hantken (1875a, b), Rozlozsnik (1929), Kecskeméti (1959, 1973), Kecskeméti & Vanová (1972), Jámbor-Kness (1981,1988) and Less (1987,1999). The smaller benthic foraminiferal fauna is also well-known from the works of Hantken (1875a) and Horváth-Kollányi (1988). Recently, planktonic foraminifera (Horváth-Kollányi, 1983) and calcareous nannoplan-kton (Báldi-Beke, 1984) are also well studied. The spatial distribution of the Hungarian epicontinental Eocene is shown in Fig. 1. Eight more or less different depositional areas can be differed whose sequences are shown in Fig. 2. All these sequences (their thicknesses vary between 300 and 700 m) lie with angular disconformity on Mesozoic rocks. The upper part is truncated in Areas I-VI whereas in Areas VII-VIII the Eocene-Oligocene transition is continuous. Different Eocene sequences are correlated on the basis of nummulitids, planktonic foraminifera and calcareous nannoplankton (Fig. 3). Magnetostrati-graphic investigation of some boreholes is also taken into consideration (Báldi-Beke & Báldi, 1991). The zonations by planktonic foraminifera and calcareous nannoplankton correspond to the world-wide standard, however the nummulitid subdivision used in Hungary has some specific features different from that of Schaub (1981) and of the shallow benthic zonation (SBZ) by Serra-Kiel et al. (1998). The main difference between them is in the interpretation of the stratigraphic range of two important nummulitid taxa, namely Nummulites perforatus and N. millecaput. In the Hungarian sections the first is always below the second that strongly contradicts to what can be seen in SW Aquitaine (see in detail in Kecskeméti, 1971). Therefore, it is necessary here to characterize schematically the Hungarian nummulitid zones (the right side of the nummulitid zonation in Fig. 3, whereas in the left the Western European zones can be found): Nummulites laevigatus Assemblage Zone: The lowest marine zone in the S Bakony, characterized by the rock-forming quantity of the nominal taxon that is a zonal marker for the whole Tethys. N. gallensis, N. lehneri, N. sismondai and N. deshayesi are constant members while N. praelorioli, N. apertus and some other persistent taxa are accessorial. Lower Lutetian. Nummulites obesus-baconicus Assemblage Zone: Corresponds to the lower part of the "Assilina spira" beds of the S Bakony in the previous literature (e.g. Kopek et al., 1971). The two nominal taxa give about 80% of the whole fauna. N. praelorioli, N. apertus, N. praeaturicus, N. majzoni, N. iohannis and N. zircensis are transitional and appearing forms. Lower-Middle Lutetian. Nummulites lorioli Assemblage Zone: Corresponds to the upper part of the "Assilina spira" beds of the S Bakony. N. lorioli with narrow stratigraphic range, N. uranensis and N. praeaturicus are the most characteristic forms. Besides, other taxa coming from the previous zone(s) or appearing here and persisting to the next zone(s) complete the fauna. Middle Lutetian. Nummulites perforatus Assemblage Zone: Characterized by the mostly rock-forming quantity of the nominal taxon. It can be found in the whole Transdanubian Mid-Mountains. Besides, a very diverse nummulitic fauna can be found with N. brongniarti, N. aturicus, N. puschi, N. sordensis, N. discorbinus and N. crassus. By the senior author of this chapter N. perforatus is an excellent zonal marker for the Upper Lutetian and Lower Bartonian, thus this zone is iso-chronic in the Transdanubian Mid-Mountains that is confirmed by its almost uniform taxonomical compo-