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Wielician (Middle Badenian) foraminifers from the stratotype area : Wieliczka Salt Mine, Poland (Paratethys, Middle Miocene)

Gonera M., Wiewiórka J., d'Obyrn K., Bukowski K.

Geological Quarterly

2014

Vol. 58, No. 3

427--438

The most abundant benthic foraminifers recorded in the Wielician salt-enclosed xenoliths are: Bulimina spp., Uvigerina spp., Valvulineria complanata, and Cibicides pseudoungerianus. The predominant taxon in the planktonic assemblage is Globigerina bulloides with a median 98.9% in biozone IIC and 89.1% in the later IID. The IIC assemblage differs from the IID one in both taxon composi tion and abundance. The most pronounced differences are those revealed by Valvulineria complanata counts, number of benfhic taxa and the plankfonic/benthic (P/B) rafio. Pseudotriplasia minuta (one of the Wielician index taxa) occurs only in the IID biozone, present in 16 among 28 samples. There is a noticeable difference in sur- face sculpture morphology pattern in the predominant Bulimina and Uvigerina taxa in the IIC versus the IID biozones. There are smooth (Bulimina elongata) and weakly striate (Uvigerina semiornata plexus) forms in the IIC biozone, foll owed by heavily costate (Bulimina striata) and spinose-pustu l ate (Uvigerina orbignyana plexus) forms in the IID. Globigerina druryi and G. decoraperta- the CPN 8 planktonic index taxa - had not been found in the material studied. Globigerinita uvula is un- usually common in the samples studied. The samples analysed display an abundance of Globigerina bulloides typical of the sub-evaporite Wielician. Hence the studied Wielician stratotype area supports the thesis of the Globigerina bulloides Acme as the valid name designation for the substage.

Isotopic events in the Early/Middle Badenian (Miocene) of the Upper Silesia Basin (Central Paratethys)

Gonera M., Bukowski K.

Geological Quarterly

2012

Vol. 56, No 3

561--568

Middle Miocene foraminifera from the Skawina Formation of the Upper Silesia Basin have been analysed. The stable oxygen and carbon isotope signatures in Globigerinoides quadrilobatus (shallow pelagic), Globigerina bulloides (deeperpelagic) and Uvigerina spp. (benthic) tests show a temporal pattern of changes in the sections studied. The foraminiferal assemblage biozones of the Badenian that were identified earlier, on the basis of taxonomic composition, correspond to changes in the foraminiferal ẟI8O and ẟI3C values. The CPN7/CPN8 transition - as the Moravian/Wielician border - is marked by distinct isotopic events: a ẟ18O increase (IIAB/IIC boundary) followed by a ẟ13C decrease (IIC/IID boundary).