Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 20. 2002. (Budapest, 2002)

58 VÖRÖS, A. Despite the slight differences, the fauna of the two levels has largely similar composition what points to a common source. The relevant pdeogeographic models (BUDAI & VÖRÖS 1992, VÖRÖS et al. 1997) identify the source area of the shell debris redeposited to the basin as the western margin/slope of the Tagyon Platform. This margin was envisaged for the Pelsonian time as running along a NW-SE trend, at 1 km distance from the present-day Horog-hegy; it was downfaulted in the Ulyrian (VÖRÖS et al. 1997, figs 3, 4). The rocky escarpments and slopes of the Tagyon Platform/Plateau could serve as biotopes of brachiopods, crinoids and other sessile benthic organisms. After death, their shells and skeletons were carried down to the neighbouring basin from time to time and were deposited as shell-beds intercalated with the basinal limestones. The marked phases of increased redeposition might be caused by sudden sea-level falls, which might be resulted in downslope removal of shelly material from the shallow areas. This model is not fully applicable in our case, because there is no consistent corelation with the regressive sequence boundaries recognised for the Balaton Highland (HAAS & BUDAI 1999). Although the "Upper Recoaro" level (Zoldianus/Binodosus Subzone) may correspond to the regressive top surface of Sequence A3 (HAAS & BUDAI 1999), the "Lower Recoaro" level (Balatonicus Subzone) coincides & PÁLFY, J. with a marked maximum flooding interval (BUDAI & HAAS 1997). Here we prefer an alternative model which is a mcxlifled version of that developed for the Jurassic brachiopod distribution and basin evolution of the Bakony Mts. by VÖRÖS (1986, 1993). There, the repeated mass accumulations of brachiopods were interpreted to be related to repeated tectonic movements along the fault-bound escarpments of submarine elevations. If we apply this interpretation to the Anisian of the Balaton Highland, the synchronous appearance of "Recoaro" limestones in different sections would reflect regional tectonic episodes. Consequently, the repeated appearance of "Recoaro" limestone in the basinal sequences marks two major phases of the fragmentation of the Anisian platforms: one in the Balatonicus Subchron, another at the end of the Zoldianus Subchron. The first phase may correspond to the first fragmentation episode of the formerly uniform Megyehegy platform or ramp, i.e. the birth of the isolated platforms such as the Tagyon platform (BUDAI & VÖRÖS 1992, HAAS & BUDAI 1999). The second tectonic phase may also be reflected in the progressive fragmentation and eventual demise of the platforms at the Balaton Irfighland (e.g. Tagyon and Szentkirályszabadja; BUDAI et al. 1993, VÖRÖS et al. 1997). ACKNOWLEDGEMENTS — This research was sponsored by the Hungarian Scientific Research Fund (Grant N° OTKA T26278). The authors are indebted to I. SZABÓ, I. SZENTE, and the late L. DOSZTÁLY for their help in fieldwork and consultations and to T. BUDAI for providing logistic support as well. Generic determination of a gastropod 0. SZABÓ) is sincerely acknowledged. The senior author thanks M. BALINI (Milano) and P. MlETTO and S. MANFRIN (Padova) for their written personal communications on the "binodosusproblem". Explanation to Plate I la-c Balatonites balatonicus (Mojsisovics, 1873), (M.2002.474), X 1.— a, c: lateral views, b: ventral view — Köveskál, Horog-hegy IV, Anisian, Balatonicus Zone (Balatonicus Subzone), 2a-b Norites cf. gondola (Mojsisovics, 1869) (M.2002.475), X 1. — a: lateral view, b: ventral view — Köveskál, Horoghegy IV, Anisian, Balatonicus Zone (Balatonicus Subzone). 3 Balatonites balatonicus (Mojsisovics, 1872) (M.200130), x 1. — Köveskál, Horog-hegy III, Anisian, Balatonicus Zone (Balatonicus Subzone). 4 Balatonites balatonicus (Mojsisovics, 1872) (M.2001.31), x 1. — Köveskál, Horog-hegy III, Anisian, Balatonicus Zone (Balatonicus Subzone). 5a-b Judicarites cf. euryomphalus (Benecke, 1866) (M.2001.34), X 1. — a: lateral view, b: ventral view — Köveskál, Horog-hegy I, Anisian, Balatonicus Zone (unnamed Subzone). 6 Beyrichites cf. beneckei (Mojsisovics, 1881) (M.2001.32), X 1. — Köveskál, Horog-hegy I, Anisian, Balatonicus Zone (unnamed Subzone). 7 Schreyerites ? cf. binodosus (Hauer, 1851) (M.2001.33), X 1. — Köveskál, Horog-hegy I, Anisian, Balatonicus Zone (unnamed Subzone). 8 Paraceratites cf. trinodosus (Mojsisovics, 1882) (M.2001.35), x 1. — Köveskál, Horog-hegy, Anisian, Trinodosus Zone (loose block). 9 Lardaroceras sp. (M.2001.36) , X 1. — Köveskál, Horog-hegy, Anisian, Trinodosus Zone (loose block). 10 Limestone slab with silicified shells of ceratitids and ptychitids, x 1. — Köveskál, Horog-hegy Anisian, Trinodosus Zone (loose block).