Acta Geologica 39. (1996)
1. szám - F. Góczán - A. Oravecz-Scheffer: Tuvalin formations of the Balaton Highland and the Zsámbék Basin. Part I.: Litho-, bio- and chronostratigraphic subdivision
2 F. Góczdti, A. Oravecz-Scheffer In connection with the chronostratigraphic classification of the examined sections, it must be emphasized that we define the Tuvalian substage in the sense of Mojsisovics (1895, p. 1298), despite the fact that no ammonite fauna has been found in these formations. Indeed, the Tuvalian age of our surface sections is determined by megalodontid and foraminifer fauna, and that of our borehole sections by sporomorph and foraminifer assemblages. Concerning Krystyn's biozonation of the substage (the described sequences contain no ammonite fauna) we cannot take a stand. 2. Historic overview In this section, we will mention the studies of those authors who contributed most significantly to the stratigraphic and paleontological investigation of the Tuvalian formations of the Balaton Highland, the Southern Bakony Mts., the Veszprém Plateau, the Keszthely Mts., and the Zsámbék Basin. Bock (1872) can be considered the author of the first monographic description. While investigating the Triassic formations of the Balaton Highland and Southern Bakony Mts, he was the first to determine the Upper Triassic age of the marl complex situated between the Füred Limestone and the Hauptdolomit. He called it "upper marl group" and correlated its upper formations with the Tor Beds ("Torer Schichten") of the Alps on the basis of their fauna (Ostrea mentis caprilis Klipstein, Pceten filosus Hauer, Corbis mellingi Hauer, Megalodus sp. (small), Waldheimia stopani Suess). At the same time, he established the chronostratigraphic classification of these formations, since most of the Tor Beds are considered to belong to the Tuvalian substage (Tollmann 1976). Fig. 1 Localities of Tuvalian sequences Acta Geologica Hungarica