|
Biostratigraphic investigations of the Middle Miocene sediments were carried out on foraminiferal and calcareous nannoplankton data from borehole samples in Vojvodina. At that time this area was a part of Paratethyan biogeographic province which was partially isolated from Mediterranean Sea. According to this, regional stages (Badenian, Sarmatian) have been used.
On the basis of foraminiferal assemblages Badenian is subdivided into Lower (Lagenidae Zone), Middle (Spiroplectammina Zone) and Upper (Bulimina/Bolivina Zone). The calcareous nannoplankton assemblage of Badenian age belongs to NN4, NN5 and NN6 zones according to Standard Nannoplankton Zonation. Lower Badenian sediments are mostly widespread Badenian sediments in Vojvodina. Lithologically they are represented by siliciclastites, organic limestones, pelitic and volcanic-sedimentary rocks. Rich planktonic foraminiferal association from Orbulina suturalis and Globigerinoides trilobus Zones is present. Lower Badenian sediments in terms of nannoplankton stratigraphy correlates with zones NN4 and NN5.
Middle Badenian sediments are determined in the northern part of Vojvodina. Lithologically they are represented with sandy and marly limestones sediments with characteristic association from Spiroplectammina carinata zone witch indicates deeper and colder sea.
Upper Badenian sediments are determined in the north-western part of Vojvodina. Lithologically they are represented with sandy and marly sediments with characteristic assemblages from Bolivina dilatata Zone.
In the northern and eastern part of Vojvodina are detremined uppermost Badenian sediments with characteristic association from Ammonia beccarii and Elphidium crispum Zone. They are represented with sandy-marly sediments and reef limestones with foraminiferal assemblages which indicate well-oxygenated warm water of normal salinity. Upper Badenian sediments in Vojvodina correspond to nannoplankton zone NN6 which base is defined by the last occurrence of Sphenolithus heteromorphus.
Sarmatian stage is divided into two substages. Lower Sarmatian is represented with Elphidium reginum and Elphidium hauerinum Zone, and the Upper Sarmatian with Porosononion granosum Zone. Due to restricted connection of Paratethys to the Mediterranean during this stage, global marker species are lacking and characteristic assemblages of calcareous nannoplankton are developed, dominated by species of Braarudosphaera, Perforocalcinella, Calcidiscus, which are present in great number of individuals.
Lower Sarmatian sediments are lithologically presented with clastites, laminated marly limestones and micrites with characteristic assemblages of foraminifers from Elphidium reginum and Elphidium hauerinum Zone.
Upper Sarmatian sediments are determined in southern and south-western part of Vojvodina. Lithologically are mostly represented with reef limestones with association of shallow water foraminifers from Porosononion granosum Zone.
|
