Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 15. 1992. (Budapest, 1992)

FRAGMENTA MINERALOGICA ET PALAEONTOLOGICA 15. BUDAPEST, 1992 p. 95-106 A Pliensbachian (Early Jurassic) Bivalve Faunula from the Harsány-hegy: First Record of the Domerian Substage from the Villány Hills (southern Hungary) by I. SZENTE and A. VÖRÖS Abstract A new temporary exposure of Lower Jurassic rocks, a nearly 8 m thick sequence of previously unknown fossiliferous limestone and chert beds is described. The bivalves and brachiopods indicate a Domerian (Late Pliensbacian) age, first recorded from the Vil­lány Hills. Bivalves, the dominant elements of the fauna represented by 7 species, are bri­efly commented. INTRODUCTION The Villány Hills are composed of several thrust sheets comprising Mesozoic sedimentary rocks steeply dipping to the south. In the Villány and Harsány thrust sheets thin beds of fossiliferous Lower and Middle Jurassic sequences are sand­wiched between thick Triassic and Upper Jurassic-Lower Cretaceous carbonate complexes. The Villány Hills has been well known among Jurassic stratigraphers and paleontologists since the monographs of Till (1910, 1911) and Lóczy (1915) describing the extremely rich Callovian ammonoid fauna. Surprisingly, the sandy and crinoidal limestone beds immediately underlying the fossiliferous Callovian strata had been regarded as Bathonian in age essentially without any evidence. The Early Jurassic age of these rocks was not recognized until 1969, when ammo­nites and brachiopods indicating the basal Pliensbacian Jamesoni Zone were col­lected and identified from the classical Templomhegy and Somsich-hegy sections near the village of Villány (Ager and Callomon 1971, Dommergues and Géczy 1989). Lower and Middle Jurassic deposits of the Villány thrust sheet and their faunas are well studied and documented. Apart from the works mentioned above, several papers were published on their sedimentology (Vörös 1972,1989) and the Jurassic belemnite (Galácz and Vörös 1969) and bivalve faunas (Vörös 1971). An account of the ammonites was given by Géczy (1984a). Due to the poor exposures, the Lower and Middle Jurassic sequence of the Harsány thrust sheet has been much less known. Crinoidal and cherty limestones underlying the Callovian were mentioned by Rakusz and Strausz (1953) and these rocks were assigned to the Pliensbachian by Vörös (1972) on the basis of a few fos­sils (Gryphaea, Spiriferina). In the early 1970's the Upper Triassic to Upper Juras­sic sequence was penetrated by drilling (I. Nagy, pers. comm.) but the results have remained unpublished. No detailed information on the Lower Jurassic deposits was available until now.

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