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

302203 Acta Geologica Hungarica, Vol. 39/1, pp. 1-31 (1996) Tuvalian sequences of the Balaton Highland and the Zsámbék Basin Part I: Litho-, bio- and chronostratigraphic subdivision Ferenc Góczán Anna Oravecz-Scheffer The lithostratigraphic units which constitute the Camian sequences of the outcrops and of boreholes drilled in the area of the Transdanubian Range, in the Balaton Highland, the Keszthely Mountains and the Zsámbék Basin, were studied from palynological and foraminifer-stratigraphic points of view. We analyzed the Tuvalian microfauna (the age of which was verified by Neomegalodon carinlhiacus (Hauer) and Cornucardia hornigii hornigii (Bittner)) as well as the sporomorph assemblages occurring with it. Knowledge of the entering and terminating taxa, as well as the changes in dominance of the taxa which form associations, made it possible to extend the evolutionary trend, known from the Cordevolian and Julian substages, of both micropalaentologic groups throughout the entire Carnian stage. Thus we were able to tag the Julian/Tuvalian substage boundary, characterize the Tuvalian foraminifer and sporomorph assemblages and correlate the studied sections. By jointly evaluating the organic and inorganic microfacies, we were able to delineate the environmental conditions of the Upper Carnian formations between the Veszprém Marl Formation and the Main Dolomite Formation. Key words: lithostratigraphy, biostratigraphy, chronostratigraphy, Carnian, Tuvalian, correlation, sporomorph, foraminifer, palaeoenvironment I. Introduction Palynologie and foraminifer investigations of Tuvalian formations of the Transdanubian Range form an integral continuation of our previous Triassic microbiostratigraphic research (Góczán et al. 1986; Loriga et al. 1990; Góczán et al. 1991; Góczán and Oravecz-Scheffer 1993). In the present study, we give an account of the results of palynostratigraphic and foraminifer-stratigraphic investigations of the formations assigned to the Tuvalian substage, which were obtained during the study of the Triassic sequences of boreholes drilled in the area of the Balaton Highland, the Keszthely Mts, and the Zsámbék Basin, and of the classic surface exposures of the Triassic in the Balaton Highland (Fig. 1). Addresses: F. Góczán: H-1138 Budapest, Dagály u. 6, Hungary A. Oravecz-Scheffer: H-1021 Budapest, Hűvösvölgyi út 74, Hungary Received: 4 April, 1995 0236-5278/96/$ 5.00 © 1996 Akadémiai Kiadó, Budapest — MAGYAR TUDOMÁNYOS AKADÉMIA KÖNYVTÁRA

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