Lithostratigraphy of the Middle Ordovician (Darriwilian) deposits of the Volkhov River, North-Vest Russia: 1. Kunda Regional Stage

We propose a detailed lithostratigraphic description of the key section of the Kunda Regional Stage (Middle Ordovician) on the Volkhov River. The section is subdivided into 35 beds, grouped into 8 members; the lowerest Khamontovo Member belongs to the Volkhov Formation, the overlying Yakhnovo, Syas, Zvanka, Izvoz, Ilinskoye, Chernavino and Simankovo Members form the Obukhovo Formation. The lower and upper “Oolite Beds” are considered only as informal subdivisions. The lithological markers (bed boundaries, discontinuity surfaces, etc.) are compared with trilobite zones and serve for a detailed correlation of Kunda deposits along the Ingermanland Klint (more than 200 km).