Results of the Study of Lamellibranchs from the Ostrog Formation of the Kuzbass

V. A. Lapshina

After a comprehensive discussion of various factual materials, the decision on the Lower Carboniferous age of the Ostrog Formation was adopted at the conference on the stratigraphy of the coal-bearing deposits of the Kuzbass, held in 1954 in Leninsk-Kuznetsky, and at the Interdepartmental Conference on the development of unified schemes for Siberia, held in 1956 in Leningrad.

The lamellibranch mollusks studied by us, collected from sections of the Ostrog Formation in the areas of the villages of Staraya Balakhonka, Ermaki, and Kameshok on the Tom River, provide new confirmation of the Lower Carboniferous age of the enclosing rocks. Below is given a characterization of the pelecypods from the three named areas.

1. In the area of the village of Staraya Balakhonka, the pelecypods were collected from the same bed of polymictic sandstone from which brachiopods and bryozoans had been studied by a number of authors. Lamellibranch mollusks occur here rather rarely, and most of them belong to the genus Aviculopecten M’Coy. In this fauna the following have been identified: Aviculopecten knockonniensis M’Coy, known in England from the Carboniferous Limestone, and in Belgium and France from the Visean stage; described by M. E. Yanishevsky from the Lower Carboniferous limestones of the Khabarny settlement area; T. A. Aleksandri-Sadova notes the presence of this species in the Lower Carboniferous deposits of Karaganda.

Pseudamusium condrustinse Demanet, described by Demanet from the Namurian deposits of Holland.

Sanguinolites occidentalis Meek et Hayden, known from the Namurian stage of Belgium.

Protoschizodus nuculiformis Kon., known from the middle part of the Visean stage of Belgium.

Aviculopecten perradiatus Kon., known from the upper Visean of Belgium and France, from the Upper Carboniferous Limestone of England, and from the Ishim beds of Kazakhstan.

Aviculopecten muromcevi sp. nov.

Aviculopecten kusbassi sp. nov.

The last two new species have no significance in resolving the question of the age of the enclosing rocks.

From the Ostrog Formation of the area of the village of Staraya Balakhonka, B. I. Chernyshev [4] described Pentagrammysia altaica Chern. R. N. Benediktova and we have established it in clayey shales exposed in the area—

near the village of Kolarovo (vicinity of the city of Tomsk), the Lower Carboniferous age of which at present is not in doubt.

1. In the area of the village of Ermaki, a large collection of lamellibranchs has been assembled from the cores of numerous boreholes, located mainly south of the village of Ermaki, where siltstones and argillites play a major role in the section of the Ostrog Formation. The following were found here:

Posidonomya corrugata R. Etheridge, characteristic of the Upper Visean. We have also encountered this species in the very uppermost part of the section of clayey shales exposed in the area of the village of Kolarovo (vicinity of the city of Tomsk).

Polidevcia karagandensis Chern., which was first cited by B. I. Chernyshev as a guiding form for the Lower Carboniferous system. B. E. Miroshnichenko [1] described this species also from the Lower Visean deposits of Karaganda.

Polidevcia mariannae Smirnova, described by N. A. Smirnova and B. E. Miroshnichenko from the Upper Visean deposits of the Karaganda basin.

Polidevcia attenuata (Flem.). This species has a broad vertical distribution: in Western Europe—in the Lower and Upper Carboniferous; in the Donets Basin—in the Middle Carboniferous; but in Kazakhstan and Western Siberia (Karaganda, Kuzbass, vicinity of the city of Tomsk, etc.) it is known so far exclusively from the Lower Carboniferous.

Nuculavus triangularis Chulga (MS)—described by P. L. Shulga from the Visean of Western Volhynia.

A large number of specimens of Solenomya costellata M’Coy were encountered. If, as D. M. Fedotov proposes, the identity of Solenomya costellata and Solenomya radiata Meek et Worthen is accepted, then the indicated species is widely distributed in the Lower Carboniferous of Europe and in the Upper Carboniferous of North America. According to the materials of D. M. Fedotov [2], this species is known from the Middle Carboniferous of the Donbas.

Solenomya parallela Beede et Rogers—first described from the Upper Carboniferous of North America; in the Donbas it occurs in the formations

$$ C^1_2;\quad C^2_2;\quad C^3_2;\quad C^6_2. $$

In addition to those listed, numerous representatives of the genus Edmondiella Chern. occur, which we have assigned to a new species, Edmondiella barsassica, also found in the clayey shales of Tomsk.

Besides the typically marine fauna, representatives of the freshwater genus Anthraconauta Pruvost (Anthraconauta ermakoviensis sp. nov.) were encountered here. This latter circumstance, as well as the presence here in large numbers of corresponding groups of phyllopod crustaceans and ostracods, indicates that the basin in which the sediments of the Ostrog Formation were formed in the area of the village of Ermaki bore noticeable traces of freshening.

The Ostrog Formation, penetrated in the area of the village of Voskresenka (Zalomenskaya Depression) by rotary borehole R-1, contains the same faunal assemblage and is represented by the same rocks as in the area of the village of Ermaki.

1. In the southeast of Kuzbass (the area of the village of Kameshok on the Tom), conditions in Ostrog time were different [3, p. 74]. The thickness of the Ostrog Formation here is 350 m; only lamellibranch mollusks are present (there is no other fauna), represented almost exclusively by freshwater and brackish-water genera Anthraconauta Pruvost, Mrassiella Ragg., Augea Khalf.; representatives of the marine genera Edmondia Kon. and Edmondiella Chern. occur rarely. The fauna is represented almost exclusively by new species.

References

1. Miroshnichenko B. E. Carboniferous lamellibranch mollusks of the Karaganda Basin. Academy of Sciences of the Kazakh SSR, 1953.

2. Fedotov D. M. Carboniferous lamellibranch mollusks of the Donets Basin. Transactions of the All-Union Geological Prospecting Association of the Scientific-Technical Administration of the USSR, issue 103, 1932.

3. Khalfin L. L. Introduction to the biostratigraphy of the coal-bearing deposits of the Kuznetsk Basin. In: Problems of the Geology of the Kuzbass, issue 1, Ugletekhizdat, 1956.

4. Chernyshev B. I. The family Grammysiidae from the Upper Paleozoic deposits of the USSR. Transactions of the Institute of Geological Sciences, Academy of Sciences of the Ukrainian SSR, issue 1, series Stratigraphy and Paleontology, 1950.

Siberian Branch of VNIGRI