SOME REGULARITIES IN THE DISTRIBUTION AND COMPOSITION OF THE BALAKHON SERIES IN SOUTHERN WESTERN SIBERIA

G. F. KRASHENINNIKOV

Introduction

For the first time in Russian literature, M. A. Usov, as early as 1920, made extensive use of the concept of coal-bearing formations in a guide to the geology of caustobioliths published by the People’s Printing House of the city of Tomsk [14]. In doing so, he drew attention to the fact that the formation of coal-bearing formations requires favorable climatic and topographic conditions, and, most importantly, the corresponding oscillatory movements, which are “the most important factor in the structure of coal-bearing deposits” [14, p. 18].

By a formation, M. A. Usov understood in this work “a group of conformably deposited beds of one natural basin,” embracing “various stratigraphic units, beginning with a system and ending with part of a stage” [ibid., p. 20]. He emphasized that “not only individual coal beds, but also the entire conformably built coal-bearing formation depends in its manifestation on oscillatory or intermittent movements of the earth’s crust” [14, p. 18].

Since that time, M. A. Usov, as is known, repeatedly addressed the problem of rock formations [15; 16]. It is also well known that his views were subjected to sharp criticism, and some of them have now been rejected, while another part has proved entirely correct, has retained its significance to this day, and will undoubtedly retain it in the future. This includes, in particular, M. A. Usov’s tendency, so clearly expressed in the 1920 work, to connect the main features of coal-bearing formations and this concept itself with movements of the earth’s crust.

In our day, the fruitfulness of the concept of rock formations is recognized by the majority of geologists, but there are still very many differences in the definition of this concept. Discussion of this question is not included in the subject of the present communication, but in order to approach correctly the material presented below, it should be noted that by a coal-bearing formation I understand a totality of paragenetically related facies, including as an obligatory member swamp facies in the form of coal beds and occupying a definite tectonic position. Various, but very definite, facies take part in the composition of coal-bearing formations; their set and the character of their alternation depend on the paleogeographic setting of the accumulation area and on changes in this setting over time. The history of the development of a formation is determined by the development of the tectonic structure and climate enclosing it.

The Balakhon Series, to which the material presented below is devoted, is widely distributed in the south of Western Siberia; it is sometimes an independent coal-bearing formation, and sometimes, as for example in the Kuznetsk Basin, it represents only a part of an even more extensive coal-bearing formation.

The doctrine of formations, as I understand it, presupposes the study of rocks in paragenetic, structural, and historical relationships. Such an approach to coal-bearing strata requires a detailed study of the deposits enclosing coal seams, and of the coals themselves; of the transition of coal-bearing series into the underlying and overlying series; of their relations with adjacent coeval deposits; and the elucidation of the tectonic and paleogeographic setting of coal formation and of its changes through time.

There is no doubt that carrying out the above-mentioned complex of studies is a long and labor-intensive task, scarcely feasible for one person. Such investigations must be conducted collectively. Having begun work in the Kuznetsk Basin three years ago, with funds chiefly from the West Siberian Geological Administration, a small group of the Laboratory of Lithology of Moscow University has sought to carry out precisely such an approach; and in the present communication, as also in the report by A. N. Volkova likewise published in this collection, some results of the work performed are summarized.

It is necessary to note that all our work was carried out with the cooperation of the West Siberian and Krasnoyarsk geological administrations, as well as the trusts “Kuzbassuglegeologiya” and “Vostsibuglegeologiya.” The entire geological and administrative staff of the geological-survey parties and expeditions of the named organizations rendered constant assistance. Without this, the work could hardly have been successfully completed.

Distribution of Upper Paleozoic Coal-Bearing Formations in the South of Western Siberia

Coal-bearing formations of Upper Paleozoic age are widely distributed in the south of Western Siberia and in the territories adjoining it. In addition to the large and well-known Kuznetsk and Minusinsk basins, coal-bearing deposits of Carboniferous and Permian age are known in many places, beginning in the south at the state border—in the Tuva region and in the Altai—and extending to the area of continuous Mesozoic deposits in the north. To the east and west these deposits extend far beyond the limits of Western Siberia, and there too the largest coal basins are associated with them: the Tunguska Basin in the east, and the Karaganda Basin and others in the west.

Throughout this enormous territory, Upper Paleozoic coal accumulation covers a considerable interval of time, from the Lower Carboniferous to the upper Permian. There is no doubt that in different areas the accumulation of coal-bearing deposits began and ended at different times; moreover, the oldest coal-bearing beds have so far been established only in the west—the Ashlyarik Formation of the Karaganda Basin, whose age is considered reliably Lower Carboniferous, although different investigators estimate it as ranging from the upper Tournaisian to the upper Viséan, i.e., the discrepancies do not exceed the limits of a single stage [9]. The youngest (among Paleozoic) coal-bearing deposits are now known in the east, where the age of the upper part of the Tunguska Formation, as well as of the upper part of the Kolchugino Series of the Kuzbass, is assessed as Upper Permian, perhaps even Triassic [1]. As for the coal-bearing formations situated within the south of Western Siberia itself, geologists still have no unanimity regarding their age [5].

At the present time, the officially accepted stratigraphic scheme is that worked out in 1956 by a conference in Leningrad, according to which:

the age of the Lower Balakhon Formation is taken to be Middle and Upper Carboniferous, and that of the Upper Balakhon Formation—Lower Permian [2]. However, not all geologists agree with this solution, and a number of researchers, including such authorities as V. I. Yavorsky, A. P. Rotai, and others, continue to insist on the Permian age of the entire Balakhon Series [11; 19].

Obviously, the question of age, important in itself, acquires decisive significance as soon as it becomes necessary to correlate particular deposits over an area, since any paleogeographic reconstructions make sense only provided that beds of the same age are being correlated. Bearing this in mind, and in view of the controversial nature of the question of the age assignment of the Upper Paleozoic coal-bearing formations and their individual parts in Western Siberia, in what follows we shall discuss the Balakhon Series and its stratigraphic analogues without yet touching upon the question of its geological age—Carboniferous or Permian.

The Balakhon Series is known in a large number of places, although sometimes under different names.

Composition and changes of the Balakhon Series on the meridian of the Minusinsk Basin

The southeasternmost point of occurrence of the Balakhon Series has been established in the southern part of the Tuvinian Autonomous Oblast, where it crops out in several places southwest of the city of Kyzyl and is known under the name of the Onkazhino Formation. This formation has been described in a number of works, in particular in the recently published article by A. L. Losev [6]. According to his data, at the base of the formation there are about 100 m of conglomerates, lying unconformably on Lower Carboniferous deposits. Above lies a sequence consisting of sandstones of various grain sizes—from fine-grained to coarse-grained—siltstones, argillites, and conglomerates. This sequence contains 9 coal seams of workable thickness; the total thickness of the formation is about 400 m. The formation shows noticeable facies changes even over a relatively short distance, expressed in the replacement of the lower conglomerates by siltstones and argillites, and also in a decrease in the number of workable coal seams.

The fossil flora is represented by forms identified by M. F. Neuburg, and permits “confident correlation of the Onkazhino Formation with the Lower Balakhon Formation of the Kuznetsk Basin \((C_2 + C_3^{bl})\)” [6, p. 49].

Farther north, a number of areas of distribution of the Balakhon Series are known already north of the main ridge of the Western Sayan, in the extensive basin of the Minusinsk Basin. The general stratigraphic section of the coal-bearing formation of this basin has been well known since the work of G. A. Ivanov [4], and recently it has been studied in detail by many researchers. In particular, G. P. Radchenko recently published its summary characterization [10]. In this work G. P. Radchenko also gives a genetic interpretation of the section, which is of especially great interest to us.

Above an 80-meter conglomerate member, lying conformably on the Lower Carboniferous Upper Minusinsk Subformation, is the Lower Sarsky horizon, containing the first coal seams of workable thickness. Higher in the section, several more productive and barren horizons are distinguished, with the total thickness of the coal-bearing sequence reaching 1500 m in the most deeply subsided troughs.

As for the stratigraphic position of the coal-bearing deposits, modern researchers are unanimous in the opinion that they correspond to the Balakhon Series of the Kuznetsk Basin, with individual members of the coal-

of the section of the Minusinsk Basin are correlated with formations and even with subformations of the Kuznetsk section. On the latter question, however, there is no unanimity among researchers: some (for example, N. S. Pedan [13]) believe that the section of the Minusinsk Basin corresponds to both formations—the Lower Balakhon and Upper Balakhon—of the Kuznetsk Basin, while others (for example, G. P. Radchenko) believe that the Minusinsk coal-bearing section fits entirely within the Ostrog and Lower Balakhon formations of the Kuzbass [10].

Many researchers have touched upon the lithological and genetic features of the coal-bearing sequence of the Minusinsk Basin. In this connection, the continental aspect of the section is noted, in the absence of clear elements of marine origin.

G. P. Radchenko, T. I. Minyaeva, and other geologists studying the Minusinsk Basin justifiably consider that the section is composed mainly of alluvial, channel and floodplain, as well as lacustrine (“lake-basin” and “lagoonal”) facies. However, with regard to the term “lagoonal facies” as applied to the coal-bearing sequence of the Minusinsk Basin, it should be noted that it is hardly correct. In fact, it is generally known that a lagoon is a part of the sea separated from it by a bar or some other barrier. Since, during the accumulation of the coal-bearing sequence of the Minusinsk Basin, the sea adjoined it from no side, it is natural that lagoonal facies cannot be present in the section of this sequence.

On the contrary, with the opinion concerning the broad participation of fluvial and lacustrine facies, judging from the cursory observations that I was able to make in 1955 on the cores of boreholes of the Chernogorsk deposit and on the shore section of the Beisk deposit, one may fully agree.

In particular, G. P. Radchenko cites very interesting data on the predominant direction of ancient river valleys during the accumulation of the main productive horizon at the southeasternmost deposit—the Askiz deposit. “As it turned out, it differs hardly at all from the east-southeast direction that characterized the main river valleys in the preceding stages of development of this same area. This indicates that the principal masses of clastic material in this part of the Khakass-Minusinsk depression, over a very long period of time, came from the eastern spur of the Kuznetsk Alatau; terrigenous clastic material was transported through the area of the Askiz mulda farther eastward and was distributed over the extensive spaces of the central part of the Khakass-Minusinsk depression” [10, p. 35].

In petrographic composition, the section of the coal-bearing sequence of the Minusinsk Basin includes a varied series of clastic, argillaceous, and organogenic rocks; moreover, the coal seams, as well as some conglomerate horizons, are fairly persistent areally and sometimes have the significance of marker horizons. Thus, I. S. Pedan notes persistent conglomerate members lying at the base of the conglomerate, Chernogorsk, and Narylkovo formations [13].

The data of all researchers, including my own observations of 1955, definitely indicate that the role of conglomerates in the section, as well as the significance of coarse-grained sandstones of graywacke composition, in general regularly decreases from the southwest to the northeast.

Thus, for example, in the sections appended to the work of G. P. Radchenko, it is clearly seen that the greatest number of conglomerate beds and their greatest thickness correspond to the extreme southwestern Askiz deposit; at the Beisk deposit, situated farther ...

to the northeast; according to I. A. Sanzher, they are already fewer in number there; still fewer occur in the next, Beloyarsk deposit; and, finally, the smallest number of conglomerate beds, their smallest thickness, and the size of the pebbles are characteristic of the northernmost Chernogorsk deposit in the Minusinsk Basin.

One can fully agree with the opinion of G. P. Radchenko that “both the total thickness and the granulometric composition of the deposits of the coal-bearing sequence regularly decrease in the direction from west to east and northeast. In the same direction, in the lower horizons of the Khakassian Formation, there is a gradual replacement and displacement of alluvial (channel and floodplain) facies types of deposits by near-shore basin and true basin facies. Parallel with this, the lower coal seams gradually pinch out in the same direction. Conversely, the upper coal seams increase their thickness toward the center of the Khakass–Minusinsk depression” [10, p. 42].

The data presented leave no doubt that the principal source of clastic material during the accumulation of the coal-bearing sequence of the Minusinsk Basin was located in the area of the southern part of the present-day Kuznetsk Alatau.

In this connection it is of interest to trace the facies changes of the coal-bearing deposits farther to the north. Important data in this respect are provided by the Beloozero deposit, situated approximately 250 km north of the Minusinsk Basin, already within the zone where Paleozoic folded systems plunge beneath the Meso-Cenozoic eastern margin of Western Siberia. In the summer of 1956, with the assistance of the Krasnoyarsk Geological Administration, which was conducting exploratory work at this deposit, and with the participation of A. P. Shchegolev, a diploma student of Moscow University, I was able to collect a rather large amount of lithological and paleontological material at the Beloozero deposit.

Structurally, the Beloozero deposit, according to the data of exploratory work by the Krasnoyarsk Geological Administration, represents a synclinal fold of almost meridional trend, with a gentle western limb and a steep eastern limb; moreover, boreholes have opened only a relatively small central part of this fold, while to the south and north the Upper Paleozoic coal-bearing sequence passes beneath thick, almost horizontally lying Jurassic deposits, and the closure of the structure there is unknown.

The stratigraphic section of the coal-bearing sequence has, according to exploratory data, an exposed thickness of about 1000 m, contains about two dozen commercial seams of long-flame coals, and, according to determinations of floristic remains made by M. K. Korovina, G. N. Troshkova, and others, corresponds to the coal-bearing sequence of the Minusinsk Basin, with which geologist M. M. Babenko even makes a horizon-by-horizon correlation. Thus, the general correspondence of the section of the Beloozero deposit to the Balakhon Series of Kuzbass (or to its lower half) is beyond doubt.

Lithologically, the productive section is characterized by the predominance of fine-clastic and clayey rocks, as well as by the complete absence of conglomerates. Very characteristic is the wide development of thin-bedded aleuritic-clayey rocks; the bedding is so fine that, when the core is broken along an uneven surface approximately coinciding with the bedding surface, a peculiar picture is obtained, resembling a relief map with contour lines. Such a “microrelief” fracture of the core is rarely encountered in the coal-bearing deposits of the Minusinsk Basin, but is common in the Beloozero deposit. Its origin is connected with the accumulation of sediments in shallow-water lakes.

with a regime of sediment accumulation that changed frequently within small limits.

Another characteristic feature of the coal-bearing sequence is the occurrence within it, especially in certain horizons, of an abundant fauna of pelecypods. This fauna is confined, as a rule, to clayey beds. At present the fauna is being studied by N. V. Ivanova, junior research associate of the Lithology Laboratory of Moscow State University; L. A. Ragozin, who has examined our collections and kindly agreed to consult on their study, considers these forms to be freshwater and close to the fauna of the Balakhon Series.

Thus, the general lithological features of the coal-bearing sequence of the Belozersk deposit indicate that it accumulated under relatively calmer conditions, more distant from the source of supply of clastic material (in comparison with the more southerly deposits). At the same time, neither my colleagues and I nor our predecessors have been able to detect any signs of marine origin in the section.

Composition and Changes of the Balakhon Series on the Meridian of the Kuznetsk Basin

Outcrops of the Balakhon Series are known far to the south of the Kuznetsk Basin. Thus, in the Altai Mountains, in the basin of the upper reaches of the Chuya River, the Kurai coal deposit has long been known [3]. The age of the coal-bearing deposits of this deposit was determined by V. A. Khakhlov, on the basis of floral remains, as Middle or Upper Carboniferous, i.e., fully corresponding to the Balakhon Series [18].

I have not yet been able to visit this deposit and study its lithology, but, judging from the data available in the literature, conglomerates and coarse-grained sandstones play a major role in the coal-bearing sequence. Oblique bedding and lenticular occurrence of many beds are characteristic of all the deposits [3]. No faunal remains have been found in these deposits; judging by their lithological features, they are purely continental formations.

The Kuznetsk Basin is an enormous area of distribution of sediments of the Balakhon Series. In the present collection a paper by A. N. Volkova is published that is devoted to the lithology of this series. Therefore I may confine myself only to a brief characterization of those features of it that are most important for further analysis.

It has long been known that the Balakhon Series of Kuzbass possesses certain features in different parts of its area of development. Thus, V. D. Fomichev, more than 15 years ago, already pointed out that the Balakhon Suite is characterized by an increase in coarseness in the eastern part of the basin—in the area of the Osinovaya, Taidon, and Usa rivers—and that, consequently, accumulation of its sediments took place through supply from the eastern and southeastern margins of the Kuznetsk Basin and erosion of the rocks of the Kuznetsk Alatau [17, p. 125]. He also noted that in the northwestern part of the basin, in the Mazurovo and Alykaevo sequences (according to modern nomenclature—subsuites), crinoids, Spirorbis, and pelecypods of marine type (dwarfed forms) were encountered. All these finds were made in the Kemerovo and Anzhero districts.

Later investigations confirmed the correctness of these statements. In particular, the work of geological-prospecting parties and expeditions of the West Siberian Geological Administration and the trust “Kuzbassuglegeologiya” yielded very interesting results in this respect.

The Tom–Usa Expedition of the West Siberian Geological Administration carried out prospecting and exploration work during several recent years in the area of the lower course of the Usa River, on its right and left banks.

…to the seams. In this connection it turned out that along the left bank of the Usa, in the middle-course stretch of the Kumzas River, the Balakhon Series is represented mainly by coarse-clastic rocks: conglomerates, gravelites, and coarse-grained sandstones, while its coal content is sharply reduced; moreover, the coals have a high ash content and are strongly metamorphosed. In addition, the deposits are disrupted by major tectonic dislocations. All these features are undoubtedly connected with the proximity of the Kuznetsk Alatau, which served not only as a source of clastic material, but also, during tectonically especially active epochs, exerted strong pressure on the Kuznetsk basin, most sharply manifested in areas immediately adjoining the Alatau.

A significant participation of coarse-clastic material is characteristic of the Balakhon Series in general throughout the southeastern margin of Kuzbass. Good exposures of conglomerates of this series are known in a number of places both along the Tom River and along its tributaries. In addition, they have been opened by numerous boreholes and mine workings in this region. It should be noted that the lithological features of these conglomerates, as well as the character of their distribution, do not testify in favor of their alluvial (river) origin. In general, according to my observations, river facies do not have in the coal-bearing strata of the Kuznetsk Basin—at any rate in the Balakhon Series—the wide distribution attributed to them by some recent investigators [8].

I, as well as my colleagues in lithological work, have come to the opinion that V. I. Yavorskii and P. F. Li are more likely correct on this question, as they attach the main significance to basin (as they call them, “shelf”) facies [20]. I shall note here, however, that I consider the expression “shelf” facies unfortunate, because a shelf is a continental shoal and the term should therefore be applied to modern and fossil shallow-water oceanic deposits; in the Balakhon Series, properly marine facies, if they occur at all, are very rare and far from present in all regions. Therefore it is better to speak of lacustrine or basin facies, and not shelf facies.

As for the conglomerates of the southeastern part of the Kuznetsk Basin, they possess a number of features that allow them to be regarded as deposits of flat alluvial fans, which at times formed at the western foot of the mountains that existed on the site of the modern Kuznetsk Alatau. These fans sometimes extended for several tens of kilometers into a shallow lake and a flat near-lake plain that existed on the site of the Kuznetsk Basin. The facies of these fans have no direct genetic connection with those lacustrine and swamp facies by which the Kuznetsk basin was at that time mainly filled; on the contrary, they constitute a foreign formation.

Such an origin is indicated by the totality of the lithological features of these conglomerates:

1. They have small thickness (units and the first tens of m).

2. A large area of distribution (hundreds, and perhaps sometimes more than a thousand km²).

3. Sharp lower and upper boundaries; at the base they sometimes rest with erosion.

4. Within the conglomerate members, coarse cross-bedding is sometimes visible; more often bedding is absent.

5. The coarsest material may be situated both at the base and at the top of the member, as well as in its middle part.

6. The size of the pebbles and the thickness of the conglomerates increase in an easterly direction.

1. The individual members are fairly persistent areally; these are not short lenses.

2. Within the members, on the contrary, a whimsical, lenticular structure is observed.

3. The organic remains in them are represented by large mineralized plant fragments, lying chaotically, as well as by sporadic lenses of bright coal, likewise formed from gelified branches and stems.

The fine-grained rocks enclosing the conglomeratic members described above, on the contrary, are predominantly lacustrine deposits and show no clear signs of floodplain genesis.

The Balakhon Series has an entirely different character in the northern part of the Kuznetsk Basin—in the Biryulinsk and Anzherka districts. There, conglomerates are almost absent from the series. Only rarely do interbeds of gravelites occur, and their thickness is very small, barely reaching one meter.

According to the data of L. M. Mysina [7], and also on the basis of special lithological investigations by A. A. Lisovenko in the Biryulinsk coal-bearing district, the Balakhon Series is represented by a sequence of predominantly fine-grained rocks: siltstones, argillites, and fine-grained sandstones with subordinate coal seams. In origin these formations apparently constitute mainly a lacustrine–marsh complex with a subordinate role of alluvial (fluvial) facies.

At the very north of the basin—in the Anzherka district—only the Lower Balakhon Formation is developed, and, as shown by the lithological investigations of G. A. Butuzova, a student completing a diploma thesis in the Geological Faculty of Moscow State University, it too is composed of fine-clastic rocks; in them fauna were found, identified by L. L. Khalfin as Chonetes sp., Lingula sp., and fragments of other indeterminate brachiopods, Cirravus jaworskii Chern., Kinerkaella balakhonskiensis (Rag.), Kinerkaellina cf. imitabilis Khalf., Angarodon gigas sp. n., Orthonaiadites triangularis Khalf., Mrassiella ex gr. magniforma Rag.

Among this fauna, the presence of brachiopods is noteworthy, indicating the influence of a marine regime on the body of water in which this fauna existed.

Thus, the lithological features of the Balakhon Series on the present northern margin of the Kuznetsk Basin are characterized by the most fine-grained deposits and by the greatest influence of marine conditions, as compared with other districts situated farther south.

Some remarks on the tectonic position of the Kuznetsk Basin

The geological structure of the Kuznetsk Basin is characterized by a certain asymmetry. It is manifested in the differing degree and differing character of tectonic disturbances along its western and eastern margins; this has been clearly shown, for example, in the work of E. M. Senderzon and G. M. Kostomanov [12].

The same asymmetry is also found in the lithological features of the Balakhon Series. In the east, and especially in the southeast of the basin, a coarsening of the clastic material in the rocks of this series is clearly perceptible, which indicates proximity to the source area. In the west, along the margin of the Salair, no such increase in the grain size of the clastic material occurs.

These differences are connected, it seems to me, with the usually insufficiently emphasized asymmetry in the tectonic position of the Kuznetsk Basin when it is regarded as an intracaledonian trough.

Indeed, the Caledonian age of the Kuznetsk Alatau and Gornaya Shoria cannot be in doubt. The situation is different, however, with the Salair, which bounds the Kuznetsk basin on the west.

The Salair is usually assigned to folded structures of Caledonian age. This is precisely how it is shown, for example, on the latest tectonic map of the USSR at a scale of 1 : 5,000,000, published in 1956 under the editorship of Academician N. S. Shatsky. This point of view seems to me inaccurate for the following reasons.

It is necessary either to abandon tectonic periodization based on West European canons, or to use them at least in approximate accordance with their meaning. In the European understanding, Caledonian folding began between the Ordovician and the Silurian, and its last phase—the Erian—falls at the boundary between the Silurian and the Devonian. Therefore, throughout the Devonian all Caledonian folded structures were land areas undergoing intense denudation, while in individual depressions within the Caledonides and along their margins there accumulated thick red-colored, purely continental clastic and volcanogenic sequences known as “Old Red.” By subsequent folding movements this “Old Red” was dislocated, but only to a moderate or weak degree.

As for the Salair, its geological history differs substantially from that of typical Caledonides. Undoubtedly, the Salair experienced a number of epochs of folding, including the Caledonian. However, it is not possible, it seems to me, to believe that these movements led to the consolidation of the Salair and to its transformation into a platform region. In fact, the presence on the Salair of sequences up to 5,000 m thick, including carbonate sediments of marine origin of the Lower and Middle Devonian, characterized by a high degree of facies variability, with a large number of effusives and strongly dislocated—all this indicates that the geosynclinal regime on the Salair in the Devonian apparently did not come to an end. Even the Lower Carboniferous, about 1,000 m thick, is represented in fine-grained facies that do not permit its formation to be attributed to the erosion of high mountains; the Lower Carboniferous on the Salair is also very strongly dislocated.

Therefore there are grounds for assigning the Salair to Hercynian, perhaps to Early Hercynian, folded structures.

The relatively younger age of the Salair as a folded structure becomes especially clear when it is compared with areas situated to the east and south of the Kuznetsk basin. Indeed, the Caledonian age of the Kuznetsk Alatau and Gornaya Shoria is very clearly emphasized by M. A. Usov’s Telbes Formation, all the features of which are so close to the “Old Red” of the Caledonides that it may confidently be regarded as the Siberian equivalent of this typical post-Caledonian formation.

If the point of view set forth above is accepted, then the tectonic position of the Kuznetsk basin also becomes sufficiently definite; namely, it proves to be a marginal trough of the Hercynian Salair. But, unlike the marginal trough that bounds the Russian Platform on the east and passes through the Cis-Urals, the Kuznetsk marginal trough is bounded (on the side of the Kuznetsk Alatau) not by an ancient Precambrian platform, but by a relatively much younger one—Caledonian, and therefore much more mobile in the Upper Paleozoic, representing, as a result of Hercynian movements, an uplifted land area that supplied clastic material both to the west—to the marginal Kuznetsk depression—and to the east—to the intra-Caledonian depression of the Minusinsk basin. To the south, however, the Kuznetsk basin is closed, because the marginal trough

there it is replaced by a marginal suture, passing through the Gorny Altai and, possibly, separating its Caledonian part from the Hercynian one.

As for the northern termination of the Kuznetsk Basin, it seems to me that there are no grounds for considering its present northern boundary to coincide with the primary margin of the marginal trough. On the contrary, as was shown above, all facies in the Kuznetsk Basin become increasingly fine-grained upward; elements of marine origin appear ever more clearly, and therefore one may think that in the Upper Paleozoic the Kuznetsk trough continued, gradually subsiding, far to the north, while its present northern boundary is of later origin; in general, the entire northern part of the Kuznetsk trough has been reworked by the Upper Paleozoic geosynclinal folding of the Ob–Yenisei (Tom–Kolyvan) fold system.

Conclusion

If the data set forth on the principal features of the lithology of the Balakhon Series are compared with the geological structure and geological history of the corresponding territories, a definite connection can be found between lithology and the general geological setting.

The most distinct source area, which supplied clastic material to the Kuznetsk and Minusinsk basins, is situated in the southern part of the present-day Kuznetsk Alatau and in Gornaya Shoria, where the oldest rocks, of Proterozoic and Lower Cambrian age, are most widely distributed. Consequently, this area, which is the most uplifted in the present structure, was also uplifted during the accumulation of the Upper Paleozoic coal-bearing formations in the depressions of the Kuznetsk and Minusinsk basins, and served as the principal source area.

Conversely, to the north, where on the present geological map the Paleozoic structure plunges and where, therefore, the Paleozoic rocks are replaced by a cover of Jurassic, Cretaceous, and still younger deposits, the strongest subsidence also took place in the Upper Paleozoic; therefore fine-grained sediments were widespread there—predominantly lacustrine in the east (the Beloozersk deposit) and coastal-marine in the west (the Anzhero district of the Kuznetsk Basin).

From the material set forth above a number of conclusions follow, the chief of which is that Upper Paleozoic coal accumulation in the south of Western Siberia proceeded in a certain correspondence with the general geological structure of this territory, clearly reflected also on its present geological map. Therefore, using the available information on the coal-bearing Upper Paleozoic proper, as well as data on the geological structure of this entire extensive territory, one can outline a certain prognosis regarding the character of coal-bearing capacity in those areas where it is still unknown.

Thus, one may think that the area of Gornaya Shoria, the Gorny and Rudny Altai was never an area of extensive development of Upper Paleozoic coal-bearing formations. There they accumulated in initially isolated depressions of small size, consisting of intermontane basins and grabens elongated parallel to the strike of the Caledonian structures, i.e., approximately from south to north. Naturally, coal accumulation there proceeded under purely continental conditions.

Northward, in accordance with the subsidence of the Caledonian and Early Hercynian structures, coal-bearing deposits occupied ever larger areas and were characterized by increasingly paralic conditions of coal accumulation. Therefore one may think that within the area of the present Kulunda Steppe, beneath the Cenozoic cover, considerable coal-bearing areas may have been preserved, although unfavorable for their preservation ...

...factor should be those Late Hercynian folded arcs which extend there and connect the Tom–Kolyvan zone with the Zaisan zone. But even within these arcs there may be depressions with more tranquil tectonic conditions, in which coal-bearing strata may be of practical interest.

In the discovery of such areas, geophysical observations should have primary importance. In this connection such observations must, first, identify areas with shallow occurrence of the Paleozoic, and, second, within such areas large depression structures must be found. It is precisely in them that major coal-bearing areas may occur.

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