Lower Cretaceous calcareous nannofossils from the Southern Apuseni Mountains, Romania

Abstract

ABSTRACT. We investigated Lower Cretaceous calcareous nannofossils from Southern Apuseni Mountains. The studied section from Bucium Cerbu quarry is characterized by flysch deposits (rhythmical interbedded marls and sandstones), which were assigned to the Căbeşti Formation. The studied nannofossil assemblages yielded a high diversity. The Early Aptian age of the studied deposits was assigned based on both the Tethyan and Boreal calcareous nannofossil zonations. Several reworked Valanginian nannofossils were also observed in the Early Aptian in situ nannofloras. The nannofloras are dominated by tethyan and cosmopolitan species. Besides Boreal species are also present. The presence of boreal taxa (e.g., Kokia borealis, K. stelatta) in the Tethyan Realm reflects the palaeobiogeographical distribution and the biotic changes between Tethys and Boreal Realms in the Southern Apuseni Mountains. In the studied assemblages, the dominant species are Diazomatolithus lehmanii and Watznaueria barnesiae, which can reflect a high fertility in the surface water masses.

Biostratigraphy and palaeoenvironmental interpretation of the Dalichai Formation (Lower Cretaceous) in the eastern and central Alborz Mountains (North Iran) based on calcareous nannofossils

“…Nannoconus abundans and N. bo re alis are en demic spe cies of the Bo real do main (Mutterlose, 1992) that are re corded here in the Tepal sec tion. Vulc (2008) con sid ered that the pres ence of Bo real nannofossils in the Tethyan Realm re flects their palaeo -biogeographical dis tri bu tion and bi otic shifts be tween Tethyan and Bo real wa ters, and the pres ence of nannofossils of both domains to gether can show a ma jor ex change of wa ter masses be tween these two realms. The pres ence of Nanno conus abundans and N. bo re alis in the Dalichai For ma tion may re flect a con nec tion be tween the Bo real and Tethyan realms in the Lower Barremian.…”