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Early Badenian transgression on the outer flank of Western Carpathian Foredeep, Hluchov area, Czech Republic

Hladilová Š., Nehyba S., Zágoršek K., Tomanová-Petrová P., Bitner M. A., Demeny A.

Annales Societatis Geologorum Poloniae

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2014

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Vol. 84, No. 3

259--279

EN

This multidisciplinary study, based on borehole cores from the Hluchov area in Czech Republic, documents an early Badenian marine transgression on the outer flank of the Western Carpathian Foredeep. The shallow-marine deposits represent coastal transgression over a terrestrial topography of weathered pre-Cenozoic bedrock. The lower facies association (FA1) consists of siliciclastic sediment derived from local substrate erosion. Facies indicate a wave-dominated environment with unstable bottom, variable rate of sediment supply and an incremental rise of relative sea level. The upper facies association (FA2) consists of carbonates indicating a major landward shift of shoreline, decline in siliciclastic input and further sea-level rise. The succession represents a transgressive to highstand systems tract. The maximum flooding surface, ca. 1 m above the FA1/FA2 boundary, is signified by an anomalous decrease in K and Th, an increased Th/K ratio and highest U concentration. The heavy-mineral assemblages in FA1 confirm local sediment provenance, whereas those in FA2 indicate broader sediment derivation, including volcanic component from contemporaneous rhyolitic to rhyodacitic eruptions. The deposits contain a wide range of marine fauna, with the foraminifers and molluscs indicating an early Badenian age. Molluscs, bryozoans and echinoderms indicate a normal-salinity environment with a decreasing hydraulic energy. Foraminifers indicate salinity fluctuations in the lowest part of the succession. The isotopic composition of mollusc shells shows marked inter-species differences and a general negative shift in the δ13C and δ18O values, indicating diagenetic alteration. The impact of diagenetic processes appears to have been controlled by sedimentary facies. The highly negative δ13C and δ18O values correspond to sediment layers with the highest Th/K ratios and hence low clay content. Sediment permeability was thus probably crucial in controlling the differential circulation and impact of diagenetic fluids.

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Middle Miocene zeolite-bearing turbidites, Abrămuţ Basin (Pannonian Basin), NW Romania

Bojar A. V., Barbu V., Bojar H. P.

Geological Quarterly

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2012

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Vol. 56, No 2

261-268

EN

Detailed lithostratigraphic data from a borehole in the Abrămuţ Basin, located in the northwestern part of Romania, has revealed the presence of turbiditic deposits containing several layers with tuff/tuffaceous materials in the lower Badenian. The age of these deposits is determined by the presence of the foraminifera Praeorbulina glomerosa and Orbulina suturalis. Detailed quantitative and qualitative X-ray diffraction data (XRD) on 10 different tuff layers situated at depths between 2450 and 2640 m show a mineralogical association comprising analcime, quartz, volcanic glass, smectite, mica, calcite, K-feldspar, glass and minor quantity of chlorite and albite. The presence of analcime suggests that the albite isograd for the interval studied has been never reached and the maximum temperatures have been lower than c. 125degrees C since the early Badenian.

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Sedimentological and palaeocological records of the evolution of the south west ern part of the Carpathian Foredeep (Czech Republic) during the early Badenian

Nehyba S., Tomanová Petrová P., Zágoršek K.

Geological Quarterly

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2008

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Vol. 52, No 1

45-60

EN

The depositional environment of the southern part of the Carpathian Foredeep in the Czech Republic was studied in two boreholes using sedimentological and palaeontological methods. Eight lithofacies were recognised within cores of the early Badenian deposits, comprising two facies associations, namely deposits of a coarse-grained Gilbert delta and offshore deposits. As sem blages of foraminifers document the early Badenian (Middle Miocene age). Two types of assemblages were recognised: (1) primary taphocoenoses reflecting the original environment of sedimentation, i. e. a relatively deep sublittoral (circalittoral) environment with low to normal ox ygen bottom conditions and deep-water euryoxibiont foraminifers, numerous planktonic foraminifers, agglutinated foraminifers and mixed assemblages of deep- and shallow-water foraminifers, (2) secondary taphocoenoses of shallower sublittoral (infralittoral) condition redeposited into the basin by gravity currents. These assemblages contain shallow-water foraminifers coupled with an abundant and diverse bryozoan fauna.