FAUNAL CHARACTERIZATION OF THE BALAKHON SERIES SECTION OF KUZBASS IN THE AREA OF THE KRAPIVINSKY DOME

Zmeinka River Basin

R. N. Benediktova

As is known, the section of the Balakhon series in the area of the Krapivinsky dome differs from sections of this series in other areas of Kuzbass both in thickness and in the character of the coals. The facies features of the deposits of the Balakhon series in this area still require clarification; in resolving this question, the study of the fauna, which has also proved to possess certain distinctive features, should provide some assistance.

Until now the fauna from this area has not been studied, unless one counts the species Cirratus jaworskii Chern. among barnacle crustaceans, representatives of which were collected along the Mungat River and described by B. I. Chernyshev [4], and several specimens of pelecypods belonging to the widely distributed species Anthraconauta gigantea (Rag.), delivered to D. M. Fedotov [2] from the area of the former Poryvaiskii mine.

We are able to give a general characterization of the fauna of the Balakhon series of this area on the basis of collections made by S. G. Gorelova and N. P. Burova. These collections date from 1951 and 1952 and, although represented by two small collections, make it possible to establish certain new features of the fauna, especially for the Mazurovo subformation. The preservation of the fauna is usual: sculptural (“external”) molds and impressions; specimens of lingulids have in part preserved the substance of the valves; some bedding surfaces are entirely covered with impressions, while other core samples contain only one or two such specimens.

In its composition the fauna is fairly diverse: pelecypods predominate; besides them there occur brachiopods, barnacle crustaceans, phyllopod crustaceans, and worms.

In the pelecypod fauna two known assemblages are clearly distinguished: the first is the Alykaevo fauna, distributed in Kuzbass in the Mazurovo and Alykaevo subformations, and the Late Balakhon fauna, confined to the upper parts of the Upper Balakhon suite [3].

The fauna is distributed extremely unevenly in the section. In the deposits of the Ostrog suite no fauna was collected. In the very lowest parts of the Lower Balakhon suite, in the interval of the Dyuryaginskii—Tarasovskii seams, no fauna was found. Higher in the section, very rare specimens of small brachiopods and pelecypods of marine aspect begin to occur; they were found in five beds:

floor of the Tarasovskii seam — Lingula sp.;
5 m above the Sluchainyi seam — Lingula sp.;

10 m below the Lepidophyte bed—Chonetes sp.;
the roof of the Lepidophyte bed—Edmondia (?) sp.;
3 m above the Lepidophyte bed—Chonetes sp.

Still higher in the section the brachiopods disappear, but numerous pelecypods appear, accompanied by crustaceans and worms. This fauna was found in 11 faunal layers (from bottom to top):

25 m below the Zmeinsky 1 bed: Cirravus jaworskii Chern., Mrassiella magniforma Rag., Kinerkaella sp., Augea longa Khalf.

16.5 m below the Korshinny bed: Cirravus jaworskii Chern.

9.5 m below the Korshinny bed: Kinerkaella sp., Phyllopoda.

5 m below the Korshinny bed: Cirravus jaworskii Chern.

10 m above the Korshinny bed: Mrassiella magniforma Rag., Cirravus jaworskii Chern.

12 m above the Korshinny bed: Cirravus jaworskii Chern., Cirravus sp., Kinerkaella sp.

62 m below the Tomsky 1 bed: Kinerkaella cf. balakhonskiensis (Rag.).

50 m below the Tomsky 1 bed: Kinerkaella balakhonskiensis (Rag.).

20 m below the Tomsky 1 bed: Phyllopoda, Spirorbis sp.

20 m above the Tomsky II bed: Cirravus jaworskii Chern.; Mrassiella magniforma Rag., Mrassiella sp., Kinerkaella balakhonskiensis (Rag.), Kinerkaella sp.

52 m below the Molodezhny bed: Cirravus sp.

Farther upward in the section the fauna disappears; only above the Verkhny bed was a single specimen of Mrassiella sp. found.

All the fauna listed above comes from the cores of boreholes drilled by the Zmeinsky party of the West Siberian Geological Administration. In the core material there is no fauna from the upper parts of the Upper Balakhon suite, but this is compensated by fauna collected from three outcrops:

Outcrop 32 (Poryvaika area, 939 m upstream along the Tom River from the mouth of the Poryvaika River): Anthraconauta gigantea (Rag.).

Outcrop 33 (Poryvaika area, 502 m upstream along the Tom River from the mouth of the Poryvaika River): Anthraconauta ex gr. gigantea (Rag.).

Outcrop 235 (60 m to the NW of borehole No. 34): Anthraconauta cf. sibirica (Rag.).

Summarizing the data presented above, in the section characterized here we can distinguish the following intervals, sharply differing in the character of the fauna: 1) the interval Tarasovsky bed—Lepidophyte bed (brachiopod fauna); 2) Zmeinsky II bed—Opolznevy bed (Alykaev fauna); 3) above the Opolznevy bed (fauna absent); 4) the upper parts of the Balakhon series (Late Balakhon fauna).

The correlation of the fauna with the coal beds was made according to the data of the geologists of the Zmeinsky party, V. I. Klepov and P. A. Stepanenko.

It should be noted that the change of the faunal complexes indicated above coincides exactly with the subdivision of the section into subsuites proposed by the Zmeinsky party, namely: according to this subdivision, the upper boundary of the Mazurovo subsuite passes above the Lepidophyte bed, and the upper boundary of the Alykaev subsuite—above the Opolznevy bed, i.e., precisely where the change of faunal complexes takes place. In other words, the Mazurovo and Alykaev subsuites have quite definite and substantially different faunal characteristics.

It should, however, be noted that other investigators (A. V. Kutukov, V. I. Budnikov) move the boundary between the Mazurovo and Alykaev subsuites upward, placing it above the Korshinny bed. Without entering into consideration of this question, we shall make only two remarks: 1) ta-

the exact position of this boundary must be confirmed paleobotanically (by leaf flora, spore-pollen complexes); 2) in this position it has no faunistic characteristic: the main change in fauna in the present section takes place within the Mazurovo subformation.

Below is given the faunistic characterization of the section in accordance with the subdivision proposed by V. I. Klepov and P. A. Stepanenko.

Mazurovo Subformation

The collections characterized here are of considerable interest in that they make it possible to outline additionally the composition of the fauna of the Mazurovo subformation. The fauna of this subformation, in general very meager, is almost unknown; information about it is exhausted by the following data:

a) in the work of D. M. Fedotov [1], from the deposits of the Mazurovo subformation in the vicinity of the village of Ishanovo, Kemerovo district, a single species is described: Anthraconaias fomitchevi (Fed.);

b) in the work of L. L. Khalfin [3] the fauna of the so-called Kinerka horizon (Shushtulëp district), which V. I. Skok refers to the upper parts of the Mazurovo subformation, is described; from this horizon L. L. Khalfin cites the following forms: Kinerkaella balakhonskiensis (Rag.), Angarodon kumsassiensis Rag., Myalinella (?) spirorbigera Khalf.

Despite the scantiness of the material available to us, it makes it possible substantially to supplement the characterization of the fauna of the Mazurovo subformation, in which were found Lingula sp.—3 specimens; Chonetes sp.—2 specimens; Edmondia sp.—2 specimens.

As can be seen, the fauna is represented by an assemblage of forms unusual for the coal-bearing deposits of Kuzbass: brachiopods and two specimens of large pelecypods, very reminiscent of the marine genus Edmondia Kon. Not a single representative of the pelecypods encountered in other areas of distribution of this subformation was found in the collection. This cannot be attributed to chance or to incomplete collecting, since pelecypods of the Alykaevo fauna were found in sufficiently large numbers higher in the section, in the Alykaevo subformation.

Brachiopods apparently quantitatively predominate in the fauna of the Mazurovo subformation of this region, which in general is not characteristic of the coal-bearing deposits of Kuzbass. Lingulids are a new element in the fauna of the Mazurovo subformation. All specimens of brachiopods have dwarf dimensions.

Alykaevo Subformation

This subformation, as is known, is the richest in fauna. Occurring everywhere within the limits of the development of the Alykaevo subformation, this fauna is very diverse in composition and abundant quantitatively. The most characteristic are brackish-water pelecypods, represented here by various species of the genera Kinerkaella Khalf., Mrassiella Rag., Kinerkaellina Khalf., Angarodon Rag., Orthonaiadites Khalf.

Typically marine groups are absent from this fauna; however, marine elements have been found in it in the form of very rare dwarf brachiopods (the genus Chonetes Fisch. from the Anzhero-Sudzhensk district), a single find of the genus Aviculopecten M’Coy from the Verkhotomskoye district, plates of cirriped crustaceans Cirratus Chern., crinoid elements (?) and worms of the genus Spirorbis.

The Alykaevo fauna is not only widely distributed in the Kuznetsk Basin, but has recently been described from the deposits of the Kainaminskoye coal-

of a coal deposit in Kazakhstan, where typical Alykaevo forms were discovered (Mrassiella magniforma Rag., Mrassiella ovata Khalf., Mrassiella cf. concinna Khalf., Augea longa Khalf., and others).

The Alykaevo fauna in the Zmeinka area was found in 17 boreholes; it contains the following forms:

1. Mrassiella magniforma — 19 specimens.
2. Mrassiella sp. — numerous fragments.
3. Kinerkaella balakhonskiensis — 10 specimens.
4. Kinerkaella sp. — numerous fragments.
5. Kinerkaellina imitabilis — 2 specimens.
6. Augea longa — 1 specimen.
7. Cirravus jaworskii — 6 specimens.
8. Cirravus sp. — 2 specimens.
9. Spirorbis sp. — 7 specimens.
10. Phyllopoda — 3 specimens.

Let us note that, along with individual specimens, the section contains bedding surfaces that are literally filled with impressions and internal molds of shells of the genera Kinerkaella and Mrassiella. Especially rich in fauna is the bed lying 20 m above the Tomsk II seam.

What stands out is the rich quantitative development of the fauna and its entirely different composition in the Alykaevo subformation as compared with the fauna of the Mazurovo subformation: not a single common form has been encountered in them; brachiopods are completely absent from the Alykaevo fauna, and the chief role belongs to brackish-water pelecypods of the genera Mrassiella, Kinerkaella, Augea, with a considerable distribution of cirripede crustaceans (genus Cirravus) and an accumulation of spirorbids in the bed lying 20 m below the Tomsk I seam.

Turning to the distribution of the fauna within the section of the Alykaevo subformation, we note the following details:

1) Remains of cirripede crustaceans (genus Cirravus) are distributed throughout the whole section of the subformation, but do not extend beyond its limits.

2) Pelecypods are distributed predominantly in the upper half of the subformation (Korshinsky seam—Beregovoi seam); in the lower part of the subformation only one bed with pelecypods was encountered—between the Zmeinsky I and Zmeinsky II seams.

3) Spirorbids were encountered only in one bed, in the upper part of the subformation; apparently they occur here in large numbers (on a small piece of core—seven specimens).

When the Alykaevo fauna of the present area is compared with that of other areas, the following differences may be established: representatives of the genera Anthraconauta Pruv. and Angarodon Rag. are completely absent from our fauna. The absence of the second of these genera, which is the leading form for the first Alykaevo fauna, is especially conspicuous. Conversely, cirripede crustaceans (genus Cirravus) in the Alykaevo sequence of the Zmeinka area are more abundant than anywhere else.

Upper Balakhon Series

In the intermediate subformation of Kuzbass, as is known, pelecypods occur extremely rarely and until now have not been described at all. The Zmeinka area is no exception in this respect—the intermediate subformation here is entirely devoid of fauna.

The Ishanovo subformation of Kuzbass is also very poor in fauna. Only from the Kemerovo area were two specimens described by D. M. Fedotov [1; 2], belonging to the species Naiadites skoki Fed. and Yavorskieilla skoki (Fed.).

Presumably belonging to the Ishanovskaya sequence is the find of Mrassiella gigantissima Khalf. from the area of Mount Karachiyak in the south of Kuzbass [3]. In our collection from this sequence, in the roof of the Upper seam, there occurred a single specimen identified as Mrassiella sp.; it belongs to a new species, which cannot be fully characterized, since in this specimen the lower-posterior end of the shell has been cut off by the boundary of the core.

The Late Balakhon fauna of Kuzbass, distributed in the Usyat subformation, differs, like the Alykaevskaya fauna, in its wide distribution and mass quantitative development. As is known, the principal feature of this fauna is the gigantism of its representatives.

In our collection the Late Balakhon fauna shows no peculiarities. It consists of 13 specimens of large pelecypods, for the most part in the form of fragments; apparently all of them belong to a single species—Anthraconauta gigantea, which is the most widespread among the Late Balakhon fauna.

The materials presented make it possible to make several observations on the conditions under which the sediments of the Balakhon series in the Zmeinka area were formed—namely, on the degree of salinity of the water in the corresponding basins.

The Mazurovskaya fauna in this area is represented by brachiopods of the genera Lingula and Chonetes, although these are clearly dwarfed; among the pelecypods only large forms occur, very reminiscent of the marine genus Edmondia, but the usual Lower Balakhon brackish-water pelecypods are entirely absent. No typically marine groups of brachiopods have been found, nor, in general, any stenohaline marine forms. Nevertheless, the numerical predominance of brachiopods is extremely important for this fauna, and is so far the only such case for the coal-bearing deposits of Kuzbass (apart from the Ostrogskaya formation). This fact undoubtedly indicates that the basin had a water salinity which, although below normal, was still so high that not only freshwater forms but also brackish-water forms (the genera Mrassiella, Kinerkaella, etc.) could no longer live in it.

Apparently the Mazurovskaya basin did not everywhere possess such salinity. In other parts of Kuzbass it was more freshened: in the south, in the Shushtulepsky area, pelecypods of the Alykaevskaya fauna lived at that time (the genera Kinerkaella, Angarodon), and in the Kemerovo area even the freshwater form Anthraconia fomitchevi occurred.

The finding of open shells of the genus Edmondia, with valves touching at the umbones, testifies to the calm conditions of the environment in which this fauna lived.

As for the Alykaevskaya subformation, it is quite evident that it was formed in a basin of different salinity. The change in the composition of the fauna, the disappearance of brachiopods and of pelecypods of marine aspect (genus Edmondia), indicates a certain freshening of the basin. But this basin was not freshwater, as is shown by the presence in the fauna of cirripedes (genus Cirravus), spirorbids, and brackish-water pelecypods.

Apparently, in Alykaevskaya time the basin here was less saline than the Mazurovskaya basin, but more saline than in other parts of the Kuznetsk Basin. This is indicated by the abundance of phyllopod crustaceans and the complete absence of representatives of the genus Anthraconauta, which in other places occur together with brackish-water pelecypods.

As for the Upper Balakhon formation, no difference in fauna can be indicated between the Zmeinka area and other parts of Kuzbass.

Thus, one may conclude that in Lower Balakhon time there were more saline basins here than in the other regions of Kuzbass; in Upper Balakhon time these differences became smoothed out, and conditions proved to be the same as in the other parts of the Kuznetsk Basin.

CITED LITERATURE

1. Fedotov, D. M. Lamellibranch mollusks of the coal-bearing deposits of the Kuznetsk Basin. Transactions of TsNIGRI, issue 97. 1937.

2. Fedotov, D. M. Pelecypods from coal-bearing deposits, chiefly of the industrial districts of the Kuznetsk Basin. Proceedings of the Academy of Sciences of the USSR, Biological Series, No. 1. 1938.

3. Khalfin, L. L. Lamellibranch mollusks of the coal-bearing deposits of Kuzbass. Transactions of the Mining-Geological Institute, ZSFAN, issue 9. 1950.

4. Chernyshev, B. I. Yearbook of the All-Russian Paleontological Society for 1931–1933, vol. X. 1935.

Tomsk Polytechnic Institute
named after S. M. Kirov