Original paper

Carboniferous cyclic sedimentation and micropaleontology of Bear Island, Arctic Norway

Gradstein, Felix M.; Davydov, Vladimir I.; Hammer, Øyvind

Abstract

A stratigraphic study was made of sediments belonging in the Bogevika Member of the Kapp Kåra Formation along Kobbebukta Beach on northern Bear Island, Barents Sea. The Bogevika Member consists of limestones, shales and sandstones organized in a series of small-scale ( 10 m thick) shoaling upward units, referred to as cycles. For the first time, Early Bashkirian ozawainellid foraminifers Plectostaffella and Semistaffella were found near the base of the Bogevika Member. Middle Bashkirian Staffelaeformis staffelaeformis and Pseudostaffella ex gr. grandis were found near the top of the member. This implies that marine transgression in the Barents Sea started about 10 myr earlier than understood sofar, i.e. Early Bashkirian instead of Late Bashkirian or beginning of Moscovian. At least nine sedimentary cycles are recognized in the Bogevika Member. The duration of the time interval (∼ 3.5–4 myr) brings the cycles within the Milankovitch frequency band (long eccentricity); this is consistent with durations of Middle Pennsylvanian cyclothems in Kansas, USA. Fusulinids Profusulinella prisca and Schubertella found near the base of the Efuglvika Member are indicative of a significant (2–3 myr) gap between the Bogevika and the overlying Efuglvika Members.

Keywords

barents seabashkirianbogevika membercyclic sedimentationfusulinid foraminiferspaleozoic stratigraphy