255 research outputs found

    Taxonomic revision of the Lake Pannon cockle subgenus Lymnocardium (Budmania) BRUSINA, 1897

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    The lymnocardiine subgenus Budmania is characterized by the most unusual and spectacular morphology in the endemic mollusc fauna of the Late Miocene – Pliocene Lake Pannon. Budmania possessed extremely high, hollow, irregular keels on its ribs, a pattern that was long considered an adaptation to the fluid, muddy substratum. Eight species were described with this pattern between 1874 and 1973. Our revision, based on the type materials and a large number of additional specimens from several collections, revealed however, that only two species can be distinguished with certainty: Lymnocardium (Budmania) ferrugineum (BRUSINA, 1874) and L. (B.) cristagalli (ROTH, 1878). The former lived in the littoral zone of Lake Pannon, on a sandy substratum, whereas the latter inhabited the sublittoral zone with a muddy bottom. This habitat partitioning challenges the interpretation of the high, hollow keels as an adaptation to a soft, muddy substratum. The occurrence of both species seems to have been restricted to the period between 7.5-7.15 Ma

    A fish otolith assemblage from the Late Miocene (Pannonian) deposits of Lake Pannon (Doba, NW Hungary)

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    Abstract A fish otolith assemblage consisting of 173 specimens was recovered from littoral sand deposits of the brackish Lake Pannon at Doba, western Hungary. Co-occurring endemic mollusks indicate the Lymnocardium ponticum Zone, thus an age of about 9 million years (Late Miocene) can be assumed. Most of the investigated otoliths belong to the family Sciaenidae. The otoliths are assigned to 6 taxa: Umbrina cirrhosoides, Umbrina aff. cirrosa, Umbrina sp., “genus aff. Umbrina” kokeni, Morone kuehni?, Gadidae indet. This otolith assemblage does not represent the ancient fish fauna of Lake Pannon, because the common prey fish (gobiids) have not been identified. Generally, the Pannonian fish fauna is characterized by a high number of sciaenid otoliths which indicate a shallow estuarine environment. The fish fauna from Doba is a unique otolith assemblage due to the co-occurrence of several Umbrina species

    A new occurrence of a classic "Árpåd-type" mollusc fauna from the Upper Miocene of Kozårmisleny, southern Hungary

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    A classic but very rare “ÁrpĂĄd-type”mollusc assemblage, representing the endemic fauna of the Late Miocene–Early Pliocene Lake Pannon, was discovered in KozĂĄrmisleny (near PĂ©cs, southern Hungary). The fossils were collected from silt layers deposited in the shallow sublittoral zone of Lake Pannon, exposed in an 8–10 m high road cut. The assemblage contained some very rare species, including the type species of the genus Lymnocardium, L. haueri (M. HÖRNES). Palynological investigations from the same layers failed to yield age-diagnostic dinofl agellates, and pointed to a brackish – freshwater depositional environment and warm temperate climate

    Incremental growth and mineralogy of Pannonian (Late Miocene) sciaenid otoliths – palaeoecological implications.

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    Ontogenetic age and body dimensions were studied on three extremely well-preserved sciaenid fish otoliths from sublittoral marls of Lake Pannon from Doba, Bakony Mts, Hungary. Macroscopic and microscopic observations offered clear evidence for the preservation of the genuine structural characteristics, for instance the bipartite incremental features. Ontogenetic ages were assigned for the three specimens as 16, 7 and 6 years by counting the annuli of the sagittae. Analytical results prove that the original aragonitic mineralogy has been preserved making them, and probably other Late Miocene teleost fossils, suitable for future microchemical analysis to reconstruct the past physicochemical environment

    A Tihanyi FormĂĄciĂł a Balaton környĂ©kĂ©n: tĂ­pusszelvĂ©ny, kĂ©pzƑdĂ©si körĂŒlmĂ©nyek, rĂ©tegtani jellemzĂ©s.

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    Revisiting the Tihany, FehĂ©rpart section, overviewing archive data, comparison with successions of nearby wells, well-logs, stratigraphic data and results of the high-resolution seismic surveys on Lake Balaton resulted a coherent picture on the depositional environment, age, stratigraphic correlation and palaeogeographic connections of the Tihany Formation. In addition to former analyses of grain-size distributions, carbonate and clay content, the sedimentary structures were investigated, a pilot study of gamma-ray measurements on the field was carried out and several orders of cyclicity were demonstrated. Besides previous palaeontological studies new fossils were collected, determined and magnetic polarity of the rocks were measured. The Tihany, FehĂ©rpart section is correlated with the Spiniferites tihanyensis dinoflagellate, the MN11 micromammal and the Limnocardium decorum sublittoral mollusc biozones. It shows normal magnetic polarity. It is underlain by open lacustrine, reverse polarity shales of the Congeria praerhomboidea zone, and is overlain by layers indicative of the Prosodacnomya zone. The latter is well definied by the radiometric age (7.9 Ma) of the overlying volcano sedimentary suite. Therefore the FehĂ©rpart section was deposited either 8.1–8.0 Ma (C4An.2n) or 8.3–8.2 Ma (C4Ar.1n chron) ago. The Tihany Formation was deposited in a variety of palaeoenvironments related to deltas entering Lake Pannon. It is built up of parasequences, i.e. shallowing up successions from below wave base to lake level generated by sediment accumulation. Parasequences were formed on the delta front or in inter-distributary bays to delta-plain swamps and distributary channels. Beyond the high frequency lake-level and partly autocyclic environmental fluctuations, most likely climatically induced fourth-order lake-level changes of about 15–30 m amplitude occurred, resulting in minor transgressions followed by repeated progradation of deltaic lobes. Although the Tihany (as well as the very alike SomlĂł) Formation is found along the rim of the hills currently, during its origin it was deposited in the same way as the Újfalu Formation known only from the subsurface of deep basins. The dynamics of deltaic settings feeding to Lake Pannon can be understood by studying the Tihany Formation in outcrops. The only difference among the two formations might be in the number of overlying delta cycles and their thickness. Both numbers were determined by rate of subsidence smaller at basement highs where Tihany Formation accumulated than at basin areas where Újfalu Formation was definied. It is suggested here to include Tihany (and SomlĂł) beds as members of the Újfalu Formation. Fourth-order sequence boundaries were recognized between the overlying progradational deltaic bodies. In the vicinity of Tihany no evidences of lake-level drops were revealed, but elsewhere small incised-valley fills point to minor lake-level drops. Overall regression interrupted by transgressive events continued on the study area until the shelf edge of Lake Pannon shifted as far to the south as 50-60 km, i.e. at about 8 Ma ago. Since then flooding events became rare and small in amplitude, then the area became a terrestrial plain. Fluvial deposits are not known from the direct vicinity, but travertines formed in small freshwater ponds fed by karst springs. The transition from lacustrine to terrestrial palaeoenvironments is part of the overall normal regression as a result of high sediment input to Lake Pannon. Large incised valleys or other evidences of recurring terrestrial conditions which could be related to third-order sequence boundaries mappable all over the Pannonian Basin were identified neither in Tihany nor in Újfalu Formations
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