Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 11. 1983. (Budapest, 1983)

FRAGMENTA MINERALOGICA et PALAEONTOLOGICA 11. 1983 p. 29-39 The Pliensbachian brachiopods of the Bakony Mts. (Hungary): a stratigraphical study By A. VÖRÖS (Received December 30, 1982) Abstract: 6250 brachiopod specimens from the Pliensbachian of the Bakony Mts. have been studied: the fauna consists of 33 genera with 101 species. This is the richest fauna known from the Mediterranean province. The brachiopods have been collected from 31 localities from different limestone facies, in most cases together with ammonites. This provides a basis for the precise determination of stratigraphical ranges of Mediterranean brachiopods. Tentatively, three brachiopod biozones have been established: (l) Cuneirhynchia ? palmata zone ( = uppermost Sinemurian + Uptonia jamesoni Zone); (2) Lokutella kondai zone ( = Tragophylloceras ibex Zone + Prodactylioceras davoei Zone); and (3) Apringia ? stoppanii zone (= Amaltheus stokesi Zone - Pleuroceras spinatum Zone = Domerian substage). Liassic brachiopods are among the most frequent Jurassic fossils of the Bakony Mts. One of the first surveyors of this region, BEUDANT (1822) took notice of small, Sharply ribbed "térébratulés" embedded in red, crinoidal limestones (Vol. 2, p. 432. ) Later authors (PAUL 1862, BÖCKH 1874, KOCH 1875, ORMÓS 1937) collected and described a considerable amount of Sinemurian brachiopods and recognized the marked similarity between these and the classical "Hierlatz" fauna. On the other hand, the knowledge of the Pliensbachian brachiopods of the Bakony Mts. was scanty and remained at a low level. "

Terebratula aspasia

" and "T. adnethica

" were mentioned by BÖCKH (1874) and "

Rhynchonella piccininii

" by VADÁSZ (1911) but only in faunal lists. Up to 1969 no more than 5 Pliensbachian brachiopod species had been known (published) from the Bakony Mts. while, at the same time, the Sinemurian taxa numbered about 80. This apparent disproportion was caused by differences in facies and in degree of exposure. The Sinemurian "Hierlatzkalk" facies is widespread and well-exposed in the Bakony Mts. and yielded rich brachiopod faunas at several localities (e. g. Úrkút: Csárda-hegy, Szentgál: Tüzköveshegy, Fenyőfő: Kék-hegy). The occurrence of similar, brachiopodal-crinoidal limestones is more restricted in the Pliensbachian and the outcrops are not easy of access. In the last two decades the Hungarian Geological Institute (directed at that time by dr. J. KONDA) carried out very detailed and extensive excavations and collections in the Bakony Mts. This activity was focused on the better understanding of the development of the lowermost Toarcian manganese ore deposits but it was epoch-making from the point of view of Jurassic stratigraphy and palaeontology too. The huge amount of Lower and Middle Jurassic fossils collected bed-by-bed was forwarded to the Palaeontological Department of the Eötvös University of Budapest where I had opportunity to begin my studies