Integrated stratigraphy and paleoceanography across the Santonian/Campanian boundary in the Budva Zone (Dinarides), Montenegro

Abstract

This paper examines the 42 m thick Upper Cretaceous sedimentary succession of the Čanj section in the Budva Zone (Dinarides), Montenegro, with a focus on planktonic foraminifera and geochemical characteristics across the Santonian/Campanian boundary. The section features well-preserved red pelagic Scaglia-type limestones with occasional chert intercalations, similar to the Cretaceous Oceanic Red Beds (CORBs) observed worldwide. An integrated stratigraphic analysis, including biostratigraphy and chemostratigraphy, was conducted to identify isotopic signals and planktonic foraminiferal species that characterize this Tethyan facies, and to locate the Santonian/Campanian boundary. The lithostratigraphic framework of the section includes distinct members (RM1, RM2, and RM3), along with a notable White Member (WM) containing black chert layers. Stable isotopes (δ¹³C_carb and δ¹⁸O_carb) and elemental composition analyses on bulk carbonate samples reveal significant shifts in isotope ratios and element concentrations corresponding to lithologic transitions within the section. The occurrence of the planktonic foraminifera Dicarinella asymetrica in the WM marks an important biostratigraphic interval in the Santonian. The multiproxy approach revealed increased paleobioproductivity and a transgressive sea level phase in the WM during the Santonian in the western Tethys. Geochemical data suggest that the long-term sea-level rise was interrupted by smaller, short-term sea-level falls during the deposition of the studied pelagites. A comparative analysis with other Mediterranean CORBs and the Bottaccione section (Italy) highlights the regional significance of the Čanj sequence.