Dzhegirgen Fm

Along the Dzhegirgen River, Karjantau Ridge. N.P. Vasilkovsky in 1939 (166, p.236). Stratotype in the upper reaches of the Dzhegirgen River, left tributary of the Koles River.

Synonym: Dzhegirgenskaya Suite, Джегиргенская св.

Lower sub-suite (thickness of 300m) - gray, medium- and thin-bedded organogenic-detrital, silicified limestones with layers of clayey limestones and argillites. In the middle and upper parts of the sub-suite, the amount of terrigenous admixture increases, and layers of tuffaceous sandstones and tuffites appear. Upper sub-suite (thickness more than 280m) is characterized by the predominance of volcanogenic rocks and variability of the lithological composition along the strike. Interbedded tuffaceous sandstones, clayey and sandy limestones, tuffaceous siltstones, tuffaceous sandstones with rare horizons of conglomerates. There is a decrease in the carbonate component upwards in the section and an increase in the number of terrigenous-volcanogenic rocks. Near the presumed centers of eruptions (Terekli, Karaarcha), in the upper part of the suite, the content of polymictic tuffs and lavas of trachybasaltic, trachyandesite-basaltic composition sharply increases, forming up to 50% of the thickness of the formation in some places.

Foraminifers Eostaffella postmosquensis Kir, Plectostaffella varvariensis (Brazhn. et Pot.), Propermodiscus krestovnikovi Raus.; Brachiopods - Gigantoproductus edelburgensis Phill., Linoproductus corrugatus M'Coy; ammonoids - Eumorphoceras sp., Reticuloceras sp.; conodonts - Gnathodus bilineatus Roundy, Declinognathodus noduliferus El. et Gr.