Agbasay Fm

It is widely developed in the Zeravshano-Gissar region in the Chakykalya typesection. It was distinguished by A.I. Lavrusenich et al. (1973a).

Synonym: Agbasayskaya Suite, Агбасайскя свита, Agbasay suite

Reference section:

The Agbasay Fm is composed of black and colored jaspers, which in the lower part contain layers of sedimentary carbonate breccia, and in the upper - interlayers, sometimes abundant, of colored silty-clayey shales. Thickness is 400-500 m.

According to the data of A. I. Lavrusenich et al. (1973a, b), in the lower part of the suite, there are remains of conodonts (Lochkovian stage) tabulate corals Pachyfavosites cf. kozlowskii Sok., P. cf. polymorphus (Goldf.), Favosites alpina Hörn., F. cf. clarus Yanet, F. nikiforovae Chekh. and rugose Tryplasma aff. asiaticum (Nikol.), Rhabdacanthia rugosum Lavrus., Neomphyma cf. originata Soshk. Higher up, remains of the Lower Emsian (Pragian stage) tabulate corals Favosites cf. placenta Rom., F. aff. goldfussi d'Orb.; rugose Farabophyllum intermedium Lavrus., Tryplasma aequabilis Lonsd. have been found. In higher parts of the section, remains of tabulate corals of the F. regularissimus zone: Favosites bijensis Sok., F. regularissimus Yanet, F. eifeliensis Nich., F. ovaliporis Hill and Jones, etc. have been discovered. The very top of the Agbasay Fm contains only rare remains of Amphipora Amphypora spissa Yavor. and primitive foraminifera Ragatheurammina suleimanovi Lip., Archaesphaera grandis Sul., A. minima Sul., Bisphaera elegans Viss., B. minima Lip., etc.

V. R. Martyshev (1970) referred the Agbasayskaya and overlying Marguzorskaya Suites (вышележащую маргузорскую Свиты), which he considered to be sub-suites of the Pushnevatskaya Suite (пушневатской свиты), to the Middle Devonian (Givetian) - lower part of the Tournaisian. In doing so, he proceeded from the idea of unconformable lying of the Pushnevatskaya Suite on different older deposits, including the Eifelian Magianskaya Suite (Мартышев считал), as well as from the predominance among numerous different-aged (from Ordovician to Tournaisian) organic remains found in these suites, of Middle, Late Devonian and early Tournaisian forms. Emphasizing the difficulties of explaining the presence in the Pushnevatskaya Suite. Considering the remnants of such a diverse fauna, V. R. Martyshev considered the Ordovician and Silurian remnants to be redeposited, while the single-chambered foraminifera, believed to have appeared in the Tournaisian age, had a wider age range (now it is proven that they appeared from the Silurian B. V. Poyarkov, 1969). One more circumstance appears significant. Noting the presence of diverse fossils in the Pushnevatskaya suite, V. R. Martyshev (1970, p.175) emphasized that "the remains of the fauna were collected by various researchers from different regions without reference to specific horizons of the general section."

D. A. Rubanov (1968) considered the entire Pushnevatskaya suite to be Tournaisian, indicating the presence of Tournaisian foraminifera in it and its transgressive occurrence on various horizons of Devonian and Silurian.

M. M. Kukhtikov (1969), Z. Z. Muftiev and A. S. Shadchinev (1970) relate the Pushnevatskaya suite to the middle-upper Carboniferous. This opinion is based on the assumption of the presence in the Zarafshan-Gissar region of only one type of section, which includes continuous carbonate deposits from the upper Silurian to middle Carboniferous. This excludes the possibility of the presence of pre-middle Carboniferous terrigenous formations. In addition, Z. Z. Muftiev and A. S. Shadchinev (1970) refer to finds in these deposits of middle Carboniferous foraminifera in several points. V. R. Martyshev (1970, p.179) wrote on this matter that "some inaccuracy is likely to have been allowed here", assuming that the authors identified deposits of different ages. This assumption of V. R. Martyshev is confirmed by the results of our studies (Lavrushevich et al., 1973c).