Kairak and Urubulak Fm

They were distinguished in 1942 in the mountains of Moroltau by B.N. Nasledov; in his opinion, there is still another, Khurusai suite (курусайская свита). E.D. Karpova showed that the latter is an analogue of the Kairak suite (кайракской свиты), metamorphosed in the exocontact zone of the Muzbulak granitoid massif (Geol. USSR, vol. 24, 1959). Subsequent studies by V.A. Korolev, B.I. Sigalov, and V.N. Baikov revealed that in other points of Karamazar, the overall dichotomous structure of the considered deposits is preserved, although a more detailed division of them is possible.

In the Karakul district, the Ordovician-Silurian deposits - O-S - were distinguished by E.F. Roman'ko and E.S. Chernykh in the valley of the river Balyandkik.

Synonym: Kairak and Urubulak suites, кайракская и урубулакская свиты

Reference section:

The described deposits are represented by rhythmically alternating quartzites, quartz, chlorite, sericite slates, claystones, and conglomerates. The thickness of individual layers varies from several centimeters to several meters. The total incomplete thickness of their deposits in the mountains of Mogoltau is 1500 m, in the mountains of Kalkanata is 4000 m. In the lower part of the section (Kairak suite) (кайракская свита), coarser clastic rocks predominate, and in the upper part (Urubulak suite) (урубулакская свита)- slates in Karamazar district.

In the Karakul district, the upper part of the section (700 m) is composed of the same schists with rare interlayers of light gray and dark gray limestones ranging from 2-3 to 80 m in thickness and a horizon of apodibazites (2-5 m).

In the mountains of Mogoltau, B.N. Nasledov found in the upper part of the Kairak suite the remains of trilobites and receptaculites of Ordovician (according to O.I. Sergeyunkova's conclusion) appearance Ogygites sp., Receptaculites sp., etc. In the mountains of Kalkanata, B.I. Sigalov discovered graptolites Climacograptus sp., Diplograptus sp., also having, according to O.N. Khaletskaya's opinion, an Ordovician appearance, approximately at the same stratigraphic level in Karamazar district.

In Karakul, at the top of the section, remnants of the corals Tryplasma cf. asisticum Nikol., Favosites aff. lasutkini Tchern., and the Amphipora Paramphipora mirabilis Yavor., P. humilis Yavor., and others.