Kshtudak Fm

Along the Kshudak River, northern slope of the Chumkartau Mountains. A.S. Shadchnev in 1967 (460, pp. 73-74) in the volume of the middle Llandovery part of the Baykungur Suite by M.M. Posokhova. A.S. Shadchnev described the lower part of the suite under the name Lyangar; on the State Geological Map-500 of Uzbekistan (460), the Lyangar Fm is included in the composition of the Kshudak Fm.

Synonym: Kshudak Suite, Кштудинская св.

Lower part, carbonaceous-siliceous-micaceous, clayey-micaceous shales. Upper part - siliceous shales, siliceous-clayey shales, argillites with layers of sandstones, siltstones, and rarely limestones and jaspers. Thickness: 900m.

In the shales (lower part of the section) graptolites (Along Oybadamsay) - *Climacograptus normalis* (Lapw.), *C. tuberculatus* Elles. et Wood., *Akidograptus acuminatus* (Nich.), *A. ascensus* Dav., *Cysrograptus vesiculosus* (Nich.), *Diplograptus modestus* Lapw., *Dimorphograptus swanstoni* (Lapw.), *Coronograptus cyphus* (Lapw.) etc., characteristic of the graptolite zones *Akidograptus acuminatus* and *Coronograptus cyphus* of the lower Llandovery. In the middle part, graptolites of the *Demirastrites triangulatus* - *Coronograptus gregarius* zone of the middle Llandovery - *Climacograptus rectangularis* (Mc'Coy), *Glyptograptus tamariscus nikolaevi* Obut et Sob., *Pernerograptus revolutus* (Kurck.), *Demirastrites triangulatus* (Hark.) etc.; higher up, graptolites of the *Demirastrites convolutus* - *Monograptus sedgwicki* zone of the upper middle Llandovery - *Cephalograptus cometa* (Gein.), *C. cometa extrema* (Bouč. et Přb.), *Monograptus sedgwicki* (Port.) etc.