Oyasa Fm

It was distinguished by N.P. Vasilyevsky in 1952.

Synonym: Oyasa suite, Oyayskaya Suite, Оясайская свита

Reference section:

The Oyasa Fm is predominantly developed in the Adrasman depression; in other structures, mainly subvolcanic and subeffusive facies of it are preserved.

The composite section of the Oyasa suite is as follows: 1 - red-colored conglomerates and sandstones with rare limestone lenses, thickness 100-300 m (basal layers of the Kyzyltau and Meshisay layers, Kokdzhetsky layer) (базальные слои кызылтауской и мешисайской толщ, кокджетская толща); 2 - pink fluidal and spherulitic liparites, their crystal lavas, tuffs, and ignimbrites, thickness 200-800 m (Kyzyltau, Shaitanbulak, Meshisay layers) (кызылтауская, шайтанбулакская, мешисайская толщи); 3 - dark gray and greenish-gray quartz latites and their crystal lavas with sandstones and tuff sandstones at the base, thickness 200 - 800 m (Kushaynaks, Rizak layers, lying with a slight erosion) (кушайнакская, ризакская толщи, лежащие с небольшим размывом); 4 - reddish-gray fluidal liparites (Taryekan layer) (тарыэканская толща), dark gray and lilac liparites (Aksay layer) (аксайская толща). Pink spherulitic liparites and their tuffs and ignimbrites (spherulitic layer) with a total thickness of 550-750 m (in the Adrasman depression); 5 - pink, cream, and reddish-gray liparites (=quartz dominant) and trachy-liparites, spherulitic liparites, their tuffs, crystal lavas, ignimbrites, thickness 300 - 1000 m (Tavak layer in the Adrasman depression) or pinkish gray fluidal and spherulitic trachy-liparites, thickness about 700 m (Koshmulin layer in the Tashkeskesken depression).

The thickness of the Oyasa suite (оясайской свиты) is 700-3400 m.

In the basal layers of the Kyzyltau layer, which begins the Oyasa suite in the Adrasman depression, L.P. Tatarynov in 1946 and V.F. Bazil in 1963 found the bones of stemocephalids and remains of flora known from deposits from the Middle Coal to the Permian periods. But one form of the remaining flora - Crassinervia sp. - appears in the late Carboniferous.