Revised Foraminiferal Taxa and Biostratigraphy of Bathonian to Ryazanian Deposits in Spitsbergen

The Bathonian to Ryazanian succession of Central Spitsbergen consists mainly of shales with high to intermediate or- ganic content, and preserves an essentially continuous foraminiferal record composed almost exclusively of agglutinating taxa. The as- semblages are reexamined in three extensively sampled sections, with supplementary material included from other localities in Spitsbergen and the Russian Arctic. The foraminiferal record of Spitsbergen is subdivided into eight interval zones, which are correlated with a Boreal ammonite zonal scheme using a graphic procedure. The age-thickness relationships reveal extremely low average sedimentation rates through the Upper Bathonian-Lower Kimmeridgian and Middle Volgian-Ryazanian intervals, suggesting the possible presence of minor hiatuses. The taxonomical revision of foraminifera was accomplished in the light of comparisons with sample material from Russian occur- rences. The emendation resulted in the proposal of two new genera, Agardhella and Calyptammina, and the following nine new species: Thuramminoides lapilliformis, Saccammina compacta, Scherochorella densiformis, Cribrostomoides subretusus, C. vallatus, Ammoba- culites areniferus, Agardhella placula, Trochammina praerosacea and Gaudryina rostellata.