Naslov
New data on the Lake Pannon (Late Miocene) dinoflagellate assemblages from Hungary (Pannonian Basin)

Autori
Baranyi, V. ; Sütő-Szentai, M. ; Magyar, I

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts Volume / - , 2013, 3-4

Skup
The 5th international workshop on the Neogene from the Central Europe and South-Eastern Europe

Mjesto i datum
Varna, Bugarska, 16.05.2013. - 20.05.2013

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Dinoflagellate cysts, Lake Pannon, Miocene, Pannonian Basin

Sažetak
Dinoflagellates of Lake Pannon, like many other fossil groups in the Pannonian Basin underwent a significant endemic radiation during Late Miocene and thse new forms enabled the establishment of several biozones. In the last two decades dinoflagellate cysts provided new information on the biostratigraphic position of the Pannonian (Late Miocene) formations in Hungary and they were useful in correlation of the borehole sequences. However, recent integration of the biostratigraphic data within a seismic stratigraphic framework revealed that some of the biozones may be contemporaneous and revision of the zones may be necessary. Taxonomy and paleoecology of the different taxa is dicussed based on the re-examination of the boreholes from the western part of the Pannonian Basin (Paks-2, Nagylózs-1, Lajoskomárom-1, Nagykozár-2, Somberek-2, Véménd-2). In additon, Late Sarmatian dinoflagellate assemblages are investigated in search for the origin of the endemic Lake Pannon taxa. Late Sarmatian palynomorph assemblages consist of marine dinoflagellates that have broad salinity tolerance like L. machaerophorum and L varium. Other dinoflagellate cysts (e. g. Hystrichokolpoma sp., H. obscura, M. choanophorum, N. balcombiana, O. centrocarpum, O. israelinum, P. golzowense, P. zoharyi, T. pelagica) and the brackish-water dinocyst Spiniferites bentorii budajenoensis are present in low proportions. The prasinophytes Mecsekia incrassata and Hidasia sp. occur frequently. M. ultima and M. spinosa are rare constituents of this assemblage. L. machaerophorum tolerates low salinites, but it is also thrives in hypersaline environments like the Persian Gulf or the Aral Sea (BRADFORD & WALL 1984, SORREL et al. 2006). According to BAKRAČ et al. (2012) the latter species together with P. zoharyi indicate open marine, distal settings. In modern seas P. zoharyi is very abundant in coastal, tropical low-salinity environments and near upwelling cells or river mouth (MARRET & ZONNEVELD 2003), therefore this association probably existed in low-salinity estuaries. Assemblages dominated by Mecsekia spp. and Cymathiosphaera spp. represent restricted environments, probably lagoons with reduced salinity. The Late Sarmatian palynomorph assemblage from the Somberek-2 borehole is characterised by the dominance of protoperinoid cysts: Selenopemphix spp. and Lejeunecysta spp. From the abundance of these cysts higher nutrient levels can be inferred either by riverine discharge or volcanic activity (BAKRAČ et al. 2012). Recently, in earliest Pannonian SÜTŐ-SZENTAI (2012) distinguished a new biozones with thin-walled S. bentorii pannonicus forms associated with M. ultima specimens under the real Mecseki ultima Zone. This fact clearly proves the unceratinity of these biozones and they may reprensent contemporaneous heteropic facies: proximal and distal settings. BAKRAČ et al. (2012) reported similiar scenario from the early Pannonian of Croatia and they also proved that the biozones Spinferites validus and Spiniferites paradoxus-Spiniferites bentorii coniunctus may represent coeval assemblages of different environments. In the future seismic profiles and biostratigraphic data from boreholes will be compared to clear the distribution of dinocyst associations. Additionally, a new deformed, cruciform morphotype of Virgodinium assymetricum SÜTŐ-SZENTAI 2010 is introduced. This morphotype appeared in the Spiniferites tihanyensis Zone and became frequent in the Galeacysta etrusca Zone associatied with S. crucifomis. It can reflect gradual lowering of salinity or other environmental stress. Slightly cruciform proximate cysts of Caspidinium rugosum are known from surface and subsurface sediments of the Caspian Sea (MARRET et al. 2004) and the Pleistocene-Holocene of the Marmara Sea (LONDEIX et al. 2009), although fossil counterparts from Miocene sediments are not known so far.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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