Some Regularities in the Tectonic Structure of the Kemerovo District of Kuzbass

V. Ya. Koudelny

(Presented by Professor A. M. Kuzmin)

The tectonic disturbance of mine fields has a great influence on exploration methods, the choice of a mining system, the mechanization of work in mines, and the stability of mine workings. It has to be taken into account in solving many problems of exploration and exploitation of deposits. The question of predicting the disturbance of mine fields is becoming a matter of current importance [1, 2]. The present article sets forth some results of a detailed study of tectonic elements in the mines and open pits of the Kemerovo district of Kuzbass.

Situated between the consolidated folded structure of the Kuznetsk Alatau and the younger structures of the Tom–Kolyvan arc, the Kemerovo district is characterized by a great variety in the tectonic structure of its fields, with their gradual complication in the western and southwestern directions. A. A. Belitsky and E. M. Pakh [2] distinguish three tectonic subzones in the area under consideration (Figs. 1, 2): 1) the near-Kuznetsk-Alatau subzone of monoclinal bedding of rocks; 2) the subzone of relatively gentle folds that inherited the trend of the folds of the Kuznetsk Alatau; 3) the subzone of intense linear folding and faults.

On the basis of our numerous observations in mines and open pits, I consider it necessary to note certain regularities in the tectonic structure of the distinguished subzones, which may be used in predicting the degree of disturbance of future mine fields.

The first subzone, located in the eastern part of the district, includes the areas of the Krokhalevsky, Biryulinsky, and Berezovsky mines. Farther south, the boundary of the subzone passes onto the eastern limb of the Kemerovo syncline, but owing to the poor study of this part of the district, its exact position has not yet been determined.

The subzone is characterized by distinctive conditions of formation of sediments and tectonic structures within it. Here, a more coarse-clastic material accumulated in large quantities. At the same time, the participation of the latter in the composition of the deposits of one or another subsuite is considerably greater than in analogous deposits of other subzones. Also characteristic is a reduction in the thickness of the deposits of the subsuites, in the number of workable coal seams, and in their total thickness. The coal-bearing deposits of this subzone did not undergo deep subsidence, as is indicated by the comparatively weak metamorphism of the coals, which increases noticeably westward on passing into other subzones.

Fig. 1. Schematic geological map of the Kemerovo district of Kuzbass (after N. M. Belinin): 1—tectonic faults; 2—stratigraphic boundaries; 3—Ilyinskaya Formation (Krasnoyarsk facies); 4—Kuznetsk Formation; 5—Upper Balakhonka Formation; 6—Lower Balakhonka Formation; 7—Ostrogskaia Formation; 8—Lower Carboniferous (Tournaisian and Visean); 9—Devonian deposits; 10—boundary of tectonic subzones; 11—tectonic subzones; 12—mine shafts.

Fig. 2. Geological structure of the tectonic belts of the Kemerovo district.

A — the Prikuznetsk-Alatau belt of monoclinal occurrence of rocks (section along I—I, Fig. 1);
B — the Topki–Afonino belt of brachyfolds (section along II—II);
V — the belt of [[unclear: name of belt]] tectonic folding in section along III—III.

1 — tectonic disturbances;
2 — coal seams: a — established, b — inferred;
3 — stratigraphic boundaries;
4 — Taldinskaya Formation ([[unclear: facies name]] facies);
5 — [[unclear: formation name]] Formation;
6 — Yerunakovskaya Formation;
7 — Ilyinskaya Formation;
8 — Ostrogskaya Formation.

For the subzone, a calm (homoclinal) occurrence of coal-bearing deposits is highly characteristic (Fig. 2, A). The coal and rock seams dip to the west at angles of 10–30°, only rarely steepening to 40–50°. Plicative disturbances are poorly developed. Supplementary folds (more often flexures) are not large and are usually associated with tectonic ruptures.

Tectonic ruptures likewise do not have any appreciable extent here. Predominantly diagonal concordant reverse faults with small displacement amplitudes—40–80 m—are encountered. Some of them can be traced over a considerable distance. Along the sides of these ruptures, especially on the hanging-wall sides, there is a rather dense network of small tectonic ruptures of the same type, with amplitudes from tens of centimeters to several meters. Small bends of the seams also occur here. The latter are weakly developed and are not characteristic. Other forms of rupture are isolated. For the search for displaced wings of coal seams in the mine fields of this subzone, all known methods may be applied, including methods of analogy and selection, as well as seam bending [3].

Despite the comparative simplicity of the structure of the fields of the subzone, complex tectonic knots are found in individual areas. They are established in places where bedding-plane displacements, small tectonic ruptures, macro- and microfolding, and jointing develop and combine in every possible way; this can also be used for predicting the structure of still unopened parts of seams.

Within the subzone, normal-cutting jointing is clearly manifested, forming systems: longitudinal, transverse, and two diagonal ones. Oblique-cutting jointing, represented by longitudinal (concordant-dipping and discordant-dipping), two transverse, and four diagonal systems, is expressed more weakly. Nevertheless, within this subzone, and especially in the Alykayevo subsuite, oblique-cutting jointing is more diverse and distinct than in other subzones of the Kemerovo district. A noticeable increase in the number of joints with traces of slipping and striation usually indicates proximity to some disturbance. As a rule, such areas prove to have more complicated mining-engineering conditions of operation.

The second subzone is located west of the first and encompasses the best-studied part of the coal-bearing deposits of the Kemerovo district, within which the Glushinskaya, Kedrovsko-Krokhalevskaya, and Promyshlennaya brachysynclinal structures are distinguished, as well as, in part, the western limb of the Kemerovo syncline with the complex of Chesnokovka folds (Figs. 1, 2, B).

The tectonic structure of this subzone differs sharply from the preceding one. It is characterized by broad brachyfolds with gentle dip angles of the limbs, arranged en echelon relative to one another, which to a considerable extent predetermined the name of the subzone. Here all three types of supplementary folds known in Kuzbass [2] can be distinguished. Especially characteristic are folds with differently oriented axes that arose along the sides of tectonic ruptures, as well as those formed in areas of bends of the axes of the main folds (the southern and northern closures of the Kedrovsko-Krokhalevskaya brachysyncline, the field of the “Promyshlennaya” mine, etc.). Each of the groups of folds distinguished here has its own features, which may be used in predicting the structure of individual areas.

The structure of the subzone cannot be considered without taking tectonic ruptures into account. The generally simple folds are to a significant degree complicated by large longitudinal ruptures (the Main thrust fault, the Borovushinsky and

the Butov overthrusts, etc.) with displacement amplitudes of hundreds of meters and having considerable extent. Often, on the flanks of faults, areas are noted with steep dip angles of the beds and a broad development of small tectonic ruptures of an overthrust–thrust character. The latter are also connected with additional folding, as was shown by S. S. Rumyantsev [4], and with intra-bed movements that led to the formation of microfolding, pinches, and boudinage of coal seams.

In contrast to the first subzone, small tectonic ruptures here are more varied. Thus, on the limbs of folds with a westerly dip, concordant reverse faults are predominantly developed; on limbs with an easterly dip—direct thrusts and sometimes discordant reverse faults. In some cases these forms of ruptures are associated with the same fault planes, as was noted by M. A. Usov [6]; however, there are also independent direct thrusts not connected with concordant reverse faults of the opposite limb of the fold.

There is also another group of ruptures, not found in the mine fields of the first subzone. Sometimes between the different forms of ruptures there are very complex mutual transitions. The fault planes of some ruptures bend in the hinges of folds, creating different geometric forms on opposite limbs. V. I. Skok proposed calling such ruptures plicatogenic [5]. A typical example of them is rupture B in the field of the “Tsentralnaya” mine.

The study of the jointing of coal and rocks in the mine fields and quarries of the subzone showed that normal-cutting jointing is also very characteristic here, forming longitudinal, transverse, and two diagonal systems. Oblique-cutting jointing is manifested somewhat more weakly both in relation to normal-cutting jointing and in relation to analogous jointing of the first subzone. However, in this subzone as well, areas with intensively developed oblique-cutting jointing are noted. They are characterized by a more complex tectonic structure, and in this sense the presence of oblique-cutting jointing in some area may be used for predicting the structure of areas not yet opened by mine workings. Moreover, small ruptures established in these areas often coincide in their bedding elements with one or several systems of oblique-cutting jointing.

The third subzone in the west directly adjoins the Tomsk thrust. Its eastern boundary is determined by a sharp change in the character of folding, as well as by a system of en echelon longitudinal ruptures. This tectonic subzone has been poorly studied. It is most reliably characterized along the bank section of the Tom River, where deposits of the Ostrog and Lower Balakhonka suites are exposed. Here, comparatively small folds overturned to the east have been established, with sharp hinges and steep dip angles of the limbs, complicated by additional folds and steep ruptures with a westerly dip of the fault planes [7].

Exploratory prospecting carried out in the area of the village of Yaranskoye in general confirmed the character of the tectonic structure of the subzone established along the bank section of the Tom River.

In the south, the subzone under consideration has been studied within the fields of the “Yagunovskaya,” “Pioner,” and “Mazurovskaya” mines, where comparatively small but very strained folds have been established (Fig. 2, В). In contrast to the second subzone, linear folds with inclined axes and sharp closures predominate here. All these folds are highly characterized by asymmetry, expressed in the fact that the limbs with an eastern

dips have steeper angles and are more often complicated by additional folds of higher orders. The latter are often encountered also in the near-hinge parts of folds. The hinge parts of near-hinge, above all anticlinal, folds are complicated by longitudinal tectonic ruptures of irregular form. In addition to these ruptures, within the subzone large longitudinal steeply dipping thrust-type ruptures have been established, with the displacers dipping to the west—northwest, which determine the imbricate structure of the subzone.

The subzone is characterized by the broad development of small tectonic ruptures, diverse in form and amplitude. Often these ruptures affect only one seam, without extending to neighboring, even closely situated, coal seams.

Small tectonic ruptures are localized directly on the flanks of larger ruptures, and also in places where additional folds develop, especially in areas of bending of axes and closure of folds. The prevailing forms of ruptures are diagonal conformable strike-slip faults, thrusts, and overthrusts. Longitudinal, including straight reverse faults, and transverse ruptures are less widespread and occur in approximately equal quantities. Under these conditions, the search for the displaced limb of a seam becomes more difficult, and the use of methods of analogy and similarity may lead to error. In searching for displaced limbs of seams in this subzone, one should keep in mind the close connection between the orientation of tectonic ruptures and the orientation of systems of fissures, especially obliquely cutting ones.

The more stressed tectonic setting of this subzone is emphasized by the broad development of pinches and swellings of coal seams. They are especially characteristic of the seams of the Mazurovo subformation.

The regularities in the tectonic structure of the Kemerovo district noted in the present work have been established and verified on extensive material from the mine geological service and may be used in carrying out exploration and mining operations.

REFERENCES

1. A. A. Belitsky. On the development of a methodology for predicting the disturbance of mine fields in Kuzbass. Izv. TPI, vol. 99. Questions of the Geology of Kuzbass, vol. 2, Tomsk, 1959.

2. A. A. Belitsky, E. M. Pakh. Regularities in the tectonic structure of the Kuznetsk Basin. In: Basic Ideas of M. A. Usov in Geology, Academy of Sciences of the Kazakh SSR, Alma-Ata, 1960.

3. P. K. Kulikov. Methods for finding the displaced limb of a seam. Ugletekhizdat, 1956.

4. S. S. Rumyantsev. Tectonic disturbances observed on the northwestern margin of Kuzbass and their explanation (an attempt to apply the theory of strength of materials to tectonics). Gornyi zhurnal, Nos. 10 and 11, 1928.

5. V. I. Skok. Kemerovo district. Mineral resources of the West Siberian Territory, vol. III, Novosibirsk, 1935.

6. M. A. Usov. Forms of disjunctive dislocations in the mines of Kuzbass. Collection on the Geology of Siberia, Tomsk, 1933.

7. V. I. Yavorsky, P. I. Butov. The Kuznetsk Coal Basin. Proceedings of the Geological Committee, 1927.