A Few Words on the Age of the Ostrog Formation of Kuzbass¹

R. N. Benediktova

At the conference in the city of Leninsk-Kuznetskii (1954), the question of the age of the Ostrog Formation was discussed in great detail; quite unanimously this formation was assigned to the Lower Carboniferous. There would be no need now to return to this question, all the more so since the new factual data that have appeared after 1954 only confirm the correctness of this decision. But the statements by V. I. Yavorskii [10] and A. P. Rotai [7, p. 46] compel us to make a number of remarks on this question.

Old arguments are again being advanced in favor of an Upper Carboniferous–Lower Permian age of the Ostrog Formation: the presence at the base of the formation of a small erosional break is interpreted as evidence of a long hiatus (from the upper Viséan to the Upper Carboniferous); certain species of brachiopods are brought closer to Upper Carboniferous or Permian species, especially to Notospirifer darwini (Morris).

To substantiate the duration of the pre-Ostrog hiatus, A. P. Rotai [7] gives a table with nine columns, in which sections of Upper Paleozoic deposits from various regions are presented, and everywhere large hiatuses are indicated, corresponding to the pre-Ostrog one. These sections belong to the most diverse structures—from the Precambrian Central Siberian Platform to the Mesozoids of Verkhoyansk. Their comparison with the section of the Upper Paleozoic marginal trough of Kuzbass is generally not very convincing because of the profound differences in the geotectonic setting that characterized these different structures in the Upper Paleozoic². In addition, there are also direct new materials that speak against these hiatuses (at least against some of them).

For example, great significance was attached [10, p. 133] to the presence of a long hiatus supposedly existing between the marine Lower Carboniferous and the deposits with the Balakhon flora in the area of the left bank of the Irtysh River (Northeastern Kazakhstan). It turned out that these notions are re-

reflect only the insufficient study of the region. Now that, for example, the Teniz-Korzhunkul deposit has been investigated, i.e., is geologically known to us better than before, it has become clear that this break does not exist; according to L. F. Dumler, the transition from \(C_1\) to deposits with the Lower Balakhonka flora is gradual, the conglomerate has proved to be intraformational, and one intrusion of granite porphyries cuts both \(C_1\) and deposits with the Balakhonka flora [2, pp. 18–19; 8, p. 11]. Thus disappeared a break that had seemed more substantiated than others, with which matters stand still worse (or better!). For example, A. P. Rotai shows a large break within the thickness of clay shales of the city of Tomsk. In doing so he places the shales of Lagernyi Sad in the Lower Permian, and the deposits of the Basandaika River with Asterocalamites in the upper Visean—lower Namurian. K. V. Ivanov [3, pp. 4–5], as a result of seven years’ study of these deposits, established, in particular, that the Lagernyi Sad sequence lies beneath the Basandaika sequence. Moreover, in the latter, according to the determinations of G. P. Radchenko [6, p. 36], there is a Visean flora, and according to our data—such index Lower Carboniferous brachiopods as the genus Torynifer Hall et Clarke, Pseudosyrinx plenis (Hall), Brachythyris suborbicularis (Hall), and others.

On Taimyr, where A. P. Rotai also indicates breaks, according to F. G. Markov [4, pp. 29–30], the Tournaisian, Visean, Namurian, and \(C_2\) are connected by gradual transitions and are conformable (which does not exclude the possibility of local breaks within long-developing positive structures).

Apparently, we may quite well consider that reference to these breaks as confirmation of an Upper Carboniferous age for the Ostrog formation proves nothing.

Let us turn to the paleontological materials. First of all, let us note that references [10, p. 135; 7, p. 48] to V. P. Nekhoroshev are some kind of misunderstanding: at that Conference we heard from him personally that he decisively supports V. B. Trizna’s opinion on the Lower Carboniferous age of the bryozoans of the Ostrog formation. All the other groups of the Ostrog fauna, except for brachiopods, as well as the entire flora, speak in favor of the Lower Carboniferous.

With regard to the brachiopods of the Ostrog formation, opinions have diverged: the same forms are compared by some authors with Lower Carboniferous species, and by others with Upper Carboniferous—Permian species. We have already examined this question in detail [1]. But one cannot fail to take into account the indication by T. G. Sarycheva and A. N. Sokolskaya [5, p. 94] of the discovery in the Ostrog formation of three specimens of such an index Lower Carboniferous form as Striatifera striata (Fischer).

Also very important for us is Harrington’s new and detailed description of the genus Notospirifer and of the species Notospirifer darwini (Morris), given by Harrington [12]. In the diagnosis of this genus it is stated: “Small, with few folds, lamellose-spiny spiriferids, probably bearing spines of the Phricodothyris type” [12, p. 115]. In the description of the species [ibid., p. 116] the sculpture is characterized in greater detail: the presence of distinct concentric lamellae is noted, along the free edge of which raised radial costellae break off, giving a spiny character to the surface of the shells. Nothing similar is observed in the Ostrog form,¹ which is erroneously compared with Notospirifer darwini; the very specific microsculpture of this form has been de—

¹ We have quoted precisely the description of the microsculpture of Notospirifer darwini according to Harrington; everyone familiar with the Ostrog form compared with this species knows that it possesses an entirely different microsculpture, but for some reason O. L. Einor (Sovetskaya geologiya, 1958, no. 1, p. 31) finds the indications of the differences between these forms “clearly unconvincing.”

…has been described in detail. This is a local form, for which we have established a new genus (Tomiopsis), although in its general appearance it is also similar to the Permian Notospirifer darwini.

The presence in the Lower Carboniferous of spiriferids similar to this species has long been known; for example, M. E. Yanishevsky [11, p. 99] described from the Lower Carboniferous of Khabarny a spirifer under the name “Spirifer darwini Morris?” This is only a manifestation of the well-known resemblance of many brachiopods of the Lower and Upper Carboniferous (and Lower Permian). The brachiopods of the Ostrog Formation are no exception, as we have already noted [1]: “This applies especially to the productids, which predominate in this fauna: they do indeed, as M. E. Yanishevsky observed, show similarity both to Lower and to Upper Carboniferous species, and, if desired, one can select among both groups specimens very similar to the Ostrog ones; the same must be said of most of the spirifers.” And although the erroneousness of bringing together (still more, identifying) a number of Ostrog brachiopod species with Upper Carboniferous or Lower Permian ones has been explained by us earlier, “nevertheless, if one confines oneself to analysis of only the brachiopods of the Ostrog Formation alone, the question of its age can hardly be resolved satisfactorily” [1]. But if the data for all groups of the fauna and flora are summed up, this formation can be assigned only to the Lower Carboniferous. Materials that appeared after 1954 once again confirm this conclusion.

The brachiopod fauna of the Ostrog Formation is far from the only one whose age is determined erroneously on the basis of an overly hasty comparison or identification of its representatives with species described from distant regions or countries. A striking example, directly related to the content of the present note, is provided by A. A. Mezhvilk’s article “Stratigraphy of the Northern Kharaulakh,” published in No. 7 of Soviet Geology for 1958.

The author of that article gives (pp. 51–52) a list of brachiopods identified by A. P. Rotay in the fauna of the Tiksi Formation. In the list we see Productus cora, Productus cf. verchoyanicus, Spirifer cf. fasciger, and a number of other analogous forms (including even Spirifer cf. rugulatus), on the basis of which a Permian age is usually unconditionally established for the corresponding deposits (A. P. Rotay, of course, assigns the Tiksi Formation to \(P_1\)). But in the Tiksi Formation (at three localities), together with these “Lower Permian” brachiopods, Lower Carboniferous foraminifers have been found. This is yet another serious warning for those who overestimate the stratigraphic significance of preliminary and approximate determinations.

REFERENCES CITED

1. Questions of the Geology of Kuzbass, issue 1. Materials of the Second Conference on the Stratigraphy of Coal-Bearing Deposits of Kuzbass. Ugletekhizdat, Moscow, 1956.

2. Dumler A. F. New data on the stratigraphy and coal content of the Carboniferous of certain deposits in the northeastern part of Central Kazakhstan. Soviet Geology, collection 46, 1955.

3. Ivanov K. V. Geology and petrography of the Lower Carboniferous and dike rocks of the environs of the city of Tomsk. Author’s abstract. Tomsk, 1956.

4. Markov F. G. Stratigraphy of the Carboniferous deposits of the Taimyr Peninsula and the northern margin of the Central Siberian Plateau. Abstracts of reports at the Interdepartmental Conference on the Development of Unified Stratigraphic Schemes of Siberia. Leningrad, 1956.

5. Protsvetalova T. N., Sarycheva T. G., Sokolskaya A. N. On the Lower Carboniferous age of the Ostrog Formation of the Kuznetsk Basin. Proceedings of the Academy of Sciences of the USSR, geological series, No. 2, 1956.

6. Radchenko G. F. New data on the stratigraphy of coal-bearing deposits of the Minusinsk Basin. Soviet Geology, collection 46, 1955.

7. Rotay A. P. Carboniferous deposits of Western Siberia. Abstracts of reports at the Interdepartmental Conference on the Development of Unified Stratigraphic Schemes of Siberia. Leningrad, 1956.

1. Tyzhnov A. V. Second Coal Geological Conference. “Soviet Geology,” coll. 46, 1955.

2. Khalfin L. L. Lamellibranch mollusks of the coal-bearing deposits of Kuzbass. Transactions of the Mining-Geological Institute, West Siberian Branch of the Academy of Sciences of the USSR, issue 9, 1950.

3. Yavorsky V. I. On the question of the stratigraphy of the Kuznetsk Basin. “Soviet Geology,” coll. 45, 1955.

4. Yanishevsky M. E. Lower Carboniferous limestone near the settlement of Khabarny, Orsk Uyezd, Orenburg Governorate. Tomsk, 1910.

5. Harrington H. J. The Permian Eurydesma fauna of Eastern Argentina. Journ. of Paleontol., v. 29, No. 1, 1955.

Tomsk Polytechnic Institute
named after S. M. Kirov

1. Statement at the Interdepartmental Conference on the development of unified stratigraphic schemes for Siberia in January 1956 in Leningrad; published in connection with the publication (Sovetskaya geologiya, 1958, No. 1) of O. L. Einor’s report at the same conference; O. L. Einor’s report sets forth a point of view unanimously rejected by the conference. (Editor’s note.) ↩

2. O. L. Einor begins his report at the same Conference (Sovetskaya geologiya, 1958, issue 1, p. 25) with the assertion that in the Upper Paleozoic different structures were for some reason characterized by similar geotectonic conditions. ↩