Khitinozoi ot prikidolskiya i zhedinskiya etazh v sondazhniya razrez R-1 Dalgodeltsi (Severozapadna Balgariya)

In North-west Bulgaria borehole R-1 Dalgodelci is the only one which drills through Silurian and Devonian sedimentary rocks in the interval between 4796.5 and 5001 m. From these rocks — dark grey shales were obtained and determined about 40 species of Chitinozoa. Five successive Chitinozoa assemblages may be divided. Assemblage I does not contain characteristic species but by analogy with other assemblages from Europe and Africa may be assumed that it is from rocks of the Pridolian Stage of the Silurian System. Assemblages II, III, IV and V are related to the Gedinnian Stage of the Devonian System. Angochitina chlupaci is characteristic of assemblage II. Assemblage III is characterized by Fungochitina longicollis, Cladnochitina labdata, Ancyrochitina fragilis brevis. Assemblage IV includes a characteristic correlate — Urochitina simplex. The species Cingulochitina plusquelleci appears in assemblage V. Thus, it was established that in the western part of the Moesian Platform on the territory of Bulgaria the studied part of the dark grey shales (conventionally related to Kalârasi Formation) belongs mainly to the Gedinnian and in parts probably to the Pridolian Stage.