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

Małgorzata Gonera, Janusz Wiewiórka, Kajetan d'Obyrn, Krzysztof Bukowski

Abstract


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 composition and abundance. The most pronounced differences are those revealed by Valvulineria complanata counts, number of benthic taxa and the planktonic/benthic (P/B) ratio. 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 surface 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, followed by heavily costate (Bulimina striata) and spinose-pustulate (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 unusually 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.

 


Keywords


Middle Miocene, foraminifers, Wieliczka assemblage, Wielician

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