Aktash Fm

Includes in SE Murghab district (Gurdumdin type section Kastanatdjilga, Buryukurmes rivers), SE Murghab district Gurdumdin type (Shin and Igrymiyu rivers). It is found in the southeastern Pamir in the central subzone (see the description of the Kuberkandinsky - Pamir horizons of the Permian). As an independent subdivision, the "Aktashskaya limestones" were first distinguished by P.D. Vinogradov in 1939. Later, they were understood as a subformation, then as a formation (Dronov, Leven, 1961).

Synonym: Aktashskaya suite, Акташская свита

Reference section:

The Aktash Fm (Акташская свита) consists of variegated and massive, mostly reef limestones up to 100-1000 m thick.

In 1968, V.I. Dronov divided the Aktash Fm into five members. * At the base of the formation lie cherts with limestone interbeds (Karakungei member (каракунгейская то1щ) 12-25 m). Above are gray, thick-bedded dolomites (Tyutyunsuikokaya member (тютюнсуfюкая толща) - 25-100 m), on which lie light-colored massive reef limestones (Shaymak member (шаймакская толЩа) - 45-800 m). Reef limestones are conformably overlain by dark gray, bedded limestones (Nayzatash member (найзаташская толща) 15-80 m). The section of the Aktash Fm is capped by gray nodular limestones, greenish marls, and calcareous sandstones (Igrimyuz member (игримьюзская толща) - 3-15 m)

In Karakungei member, containing Ladinian pectinids: Posidonia sp., Daonella reticulata (Mojs.). In Shaymak member, with Late Carnian-Early Norian ammonoids and pectinids: Trachyceras triadicum Mojs., Thisbites agricolae Mojs., Halobia cf. cassiana Mojs., Monotis salinaria (Schloth.), Megalodon damesi Hoern. and others. In Nayzatash member, containing Early-, Middle Norian ammonoids and pectinids: Paracladiscites timorensis Arth., Monotis salinaria (Schloth.). In Igrimyuz member, Early-, Middle Norian ammonoids and pectinids: Arcestes welteri Arth., Pinacoceras parma Mojs., Rhabdoceras cf. suessi Hauer, Monotis sp.