Foraminiferal biostratigraphy and palaeobathymetry of Senonian marls (Upper Cretaceous) in the vicinity of Kraków (Januszowice-Korzkiew area, Bonarka quarry) - preliminary study

In the vicinity of Kraków, Upper Cretaceous sediments rest upon the Upper Jurassic (Oxfordian) massive limestones and are developed as sands, conglomerates and marls. Foraminiferal assemblages from Upper Cretaceous sediments are dominated by calcareous benthic forms whereas planktonic foraminifers are rare and represented by Hedbergella and Whiteinella (sporadically also Marginotruncana and Globotruncana). Taxa identified in foraminiferal assemblages enable to distinguish several zones: Lower Santonian Gavelinella thalmanni partial range zone, the Bolivinoi- des strigillatus partial range zone (Upper Santonian and lowermost Turonian) and the Lower Campanian Bolivinoides decoratus partial range zone. Analysis of foraminiferal assemblages allows us to draw preliminary conclusions concerning the palaeobathymetry of the Late Cretaceous basin in the study area. Palaeobathymetric evaluations give a maximum basin depth of about 200 meters.