PROCEEDINGS
OF THE TOMSK POLYTECHNIC INSTITUTE
NAMED AFTER S. M. KIROV, HOLDER OF THE ORDER OF THE OCTOBER REVOLUTION
AND THE ORDER OF THE RED BANNER OF LABOR

Vol. 236　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1976

SOME FEATURES OF THE TECTONICS OF MINE FIELDS IN THE NORTHEASTERN PART OF THE LENINSKY DISTRICT OF KUZBASS

Yu. N. POPOV

(Presented by Professor K. V. Radugin)

The Leninsky coal-mining district is located in the central part of Kuzbass, within the area of distribution of deposits of the Kolchugino series. According to the scheme of tectonic zoning of the basin proposed by A. A. Belitsky and E. M. Pakh [2], the Leninsky district is assigned to the subzone of “linear and gentle folding” of the “Prisala ir zone of linear folds and faults.” The main elements that determined the structure of the district are a series of subparallel, broad, flat-bottomed brachysynclines elongated from northwest to southeast. Regional longitudinal disjunctives with amplitudes of up to 1500 and more meters are confined to the anticlines separating them from one another; this has determined the imbricate (block) structure of the district.

In the present article, features of the tectonics of the mine fields of the northeastern part of the Leninsky district are considered; these fields are situated at the junction of the Leninsky and Gramoteinsky blocks, separated by the regional Zhurinsky thrust fault (Fig. 1). The mines described work coal seams of the Yerunakovskaya subseries. Thus, the Em. Yaroslavsky Mine (old) and the S. M. Kirov Mine work seams of the Leninsky subformation on the northeastern limb of the Leninsky brachysyncline, in the hanging wall of the Zhurinsky thrust fault. The “Zhurinka-3” Mine carries out mining operations on the southwestern limb and the southeastern centricline of the Egozovskaya brachysyncline, in the lower seams of the Gramoteinsky formation, in the footwall of the Zhurinsky thrust fault. The same seams on the limbs and in the closure of the Egozovskaya brachysyncline are worked by the Em. Yaroslavsky Mine, located somewhat to the northeast.* A positive circumstance is the fact that the morphology of all the tectonic structures represented here has been revealed by the most reliable mine workings, which covered a fairly considerable area, including structural elements of different orders. This makes it possible to establish their interrelationship.

It has already been mentioned above that the principal plicative forms of dislocations in the mine fields of the northeastern part of the district are the Leninsky and Egozovskaya brachysynclines.

The first is a large (up to 30 km long), gentle fold. Its southeastern closure is simple, while the northwestern one, owing to a gentle anticlinal bending of the axis, has proved complicated by a series of gentle folds of different orientation. Thus its northeastern limb within the

* This name was given to the “Egozovskaya 1–2” Mine after the closure of the Em. Yaroslavsky Mine (old).

of the fields of the Em. Yaroslavsky (old) and S. M. Kirov mines is affected by closely spaced additional anticline and syncline. Both folds have gentle (up to 15°) limbs; their axes are almost transverse with respect to the axis of the Leninsk brachysyncline. Looking somewhat ahead, we note that the East-Kamyshan thrust is confined to the axial zone of the anticline (Fig. 1).

The other brachysyncline of the first order—the Egozovo—is narrower than the first. The dip angles of its limbs vary from 60–70° in the upper horizons, at the outcrops beneath the overburden, to zero in the near-hinge part. The hinge of the fold is gentle and broad, giving it a specific trough-like form. In plan, the axis of the brachysyncline forms gentle bends and is characterized by distinct undulation; as a result, only in the field of the Em. Yaroslavsky mine are two significant bends noted, which led to the closure in plan of the Dalny seam in the northwestern part of the field.

The gentle (5–15°) homoclinal occurrence of the southwestern limb of the Egozovo brachysyncline in the northwestern part of the field of the Zhurinka-3 mine is complicated by the Zhurinka anticline. This is a fairly broad asymmetric fold. The dip angles of its limbs vary within 10–60°; the northeastern limb is somewhat steeper, and a tendency is observed for its dip angles to increase northwestward as the SZh-1 disjunctive approaches. The hinge of the fold is cylindrical, with a noticeable decrease in the radius of curvature toward the northwest. The axis of the Zhurinka anticline, parallel to the axis of the Egozovo brachysyncline, plunges to the southeast at angles of 5–7°. A substantial undulation of the axis is noted.

The most widespread form of manifestation of additional plicative dislocations within the Egozovo syncline is transverse waviness, which, unlike that in the field of the Em. Yaroslavsky (old) mine, is more frequent and more intense. The transverse waves significantly complicated the driving of the main drifts, especially at the Em. Yaroslavsky mine. The increased intensity of this type of folding here is closely connected with the more complex character of the undulation of the axis of the Egozovo brachysyncline in comparison with the Leninsk one.

Along with transverse waviness, in the northwestern and southeastern parts of the field of the Em. Yaroslavsky mine, in the hinge and in the gentle near-bottom part of the southwestern limb of the Egozovo brachysyncline, in areas of significant anticlinal bends of its axis, groups of differently oriented small folds and flexures with limb dip angles of 20–25° and, more rarely, up to 38° are noted. This considerably hindered mining operations and even made it necessary to write off part of the coal reserves in the Geological seam in the southeastern part of the mine field.

The fracturing of the coal and enclosing rocks, studied in the mine fields under consideration, has a number of characteristic features. First of all, the preferential development here of fractures of normal-cutting systems should be noted. Attention is drawn to the orientation of the systems of normal-cutting fractures on different limbs of the Leninsk and Egozovo brachysynclines (Fig. 2). The maxima of the bedding elements of normal-cutting fractures in systems longitudinal and transverse to the axes of the principal folds have the following orientation: (see table).

Much less strongly within the described area did oblique-cutting fracturing manifest itself. This includes the most frequently encountered conjugate longitudinal and transverse systems of fractures, having dip angles of 15–40°. Gentle and steeply dipping fractures are rare.

Fig. 1. Character of the tectonics of the northeastern fields of the Leninsky District.
A. Schematic plan of the coal-seam outcrops beneath the overburden along the Kamyshanskaya exploration line.
1 — outcrops beneath the overburden of coal seams: a) explored; b) mined out;
2 — disjunctive faults;
3 — zones of tectonic breccias in the walls of disjunctive faults;
4 — exploration boreholes.
B. Section along the Kamyshanskaya exploration line.

diagonal, concordant- and discordant-dipping fractures (Fig. 2). Their planes usually bear intense striation, directed mainly down the dip of the fractures; their frequency is 5–1 per 1.0 m. The development of obliquely cutting fractures has been noted under conditions of some complication of the homoclinal occurrence of the beds by disjunctive or plicative forms of dislocation. In areas of simple structure they are rare. An increase in the intensity of manifestation of obliquely cutting fracturing may quite well serve as a criterion of the tectonic complexity of a given area of a mine field.

Fig. 2. Character of fracturing of coal beds. Diagram of the attitude elements of fracturing studied in the face of longwall No. 7, Podzhurinsky-1 seam, at the “Zhurinka-3” mine.

296 measurements; 0.5–1–2–3–4%.

Disjunctive forms of dislocation are widely developed in the area of the district under description. The most significant here is the regional disjunctive structure—the Zhurinsky thrust fault, which dips to the southwest (azimuth 200–220°) at an angle of 30–50°. It is one of the main longitudinal disjunctives of the district, serving as the boundary between the Leninsky and Gramoteinsky blocks. The normal amplitude of displacement along it is 1000–1200 m. The thickness of the zone of tectonic breccias on its flanks reaches 200–250 m.

The tectonics of the hanging wall of the Zhurinsky thrust fault in the field of the Em. Yaroslavsky Mine (old) is distinguished by the development of a large number of disjunctives of the second and higher orders. Among them two main groups can be distinguished: the first group includes disjunctives diagonal

Table

with respect to the strike of the northeastern limb of the Leninskaya syncline. They have been well studied in mine workings, especially in the Maksimovsky seam. These are mainly concordant disjunctives of thrust-fault character, with dip azimuths of 210–230° and dip angles of 20–50°. As is evident from Figure 3, the main mass of disjunctives that have developed in the northwestern part of the mine field belongs precisely to this group. They affect the coal beds of the field at their outcrops beneath the deposits, in immediate proximity to the Zhurinsky thrust fault, and are parallel to the latter, being traceable along strike for 1000–1500 m. The displacement amplitudes along them usually do not exceed 1.5–2.0 m. More rarely, alongside the concordant-dipping ones, there occur discordant-dipping disjunctives of the same strike, also having a thrust-fault character. These two sys-

Fig. 3. Orientation of disjunctives in the field of the Em. Yaroslavsky Mine (old): left—in the northwestern part of the field, right—in the southeastern part.

systems of conjugate disjunctives that arose in the hanging wall of the Zhurinsky reverse fault are not typical feathering disjunctives formed under the action of a pair of forces arising when the hanging wall of the displacer moves along the footwall. They formed under the influence of tangential compressive stresses along already preexisting fractures of longitudinal oblique systems.

The second group includes the transverse reverse faults, the Western and Eastern Kamyshansky. Both of these disjunctives dip to the southeast at angles of 25–40°. The normal amplitude of the first does not exceed 2.5 m, and that of the second is 22 m.

Both groups of disjunctives are accompanied by a number of smaller displacers, which creates a very complex structure, a vivid example of which is the area of the Eastern Kamyshansky reverse fault (Fig. 4).

When comparing diagrams of the attitude elements of disjunctives in the eastern and western parts of the mine field (Fig. 3), it is noted that there are no substantial differences in the orientation of the displacers, but in the western part of the field fewer transverse displacers have been recorded. This circumstance indicates that the transverse anticlinal bend created favorable conditions for the development of disjunctives along fractures of transverse oblique systems.

Consequently, the orientation of the overwhelming majority of disjunctives in the hanging wall of the Zhurinsky reverse fault in the field of the Em. Yaroslavsky Mine (old) is in close spatial and genetic connection with oblique fracture jointing. The character of the preferential manifestation of disjunctives with one or another position of the displacer was influenced by the plicative structure.

As to the form of the disjunctives in the hanging wall of the Zhurinsky reverse fault, it may be said that it is not marked by great variety, if one takes into account that the bedding of the wall is homoclinal, and that the orientation of the displacers is almost completely exhausted by two pairs of systems of conjugate longitudinal and transverse disjunctives oblique with respect to the axes of the principal folds, and all of them have a reverse-fault character. Within the field of the Em. Yaroslavsky Mine (old), 2–3 disjunctives with an almost vertical dip of the displacer have been encountered.

The concentration of a significant number of disjunctives in the mine field under consideration is associated by A. A. Belitsky [1] with transverse bends of the seams, which led to uneven flattening of the dip angles of the northeastern limb of the Leninskaya syncline. The presence of such waviness evidently hindered the release of stresses at the expense of inter-

Fig. 4. Manifestation of disjunctive faulting in the walls of the Vostochno-Kamyshanskii thrust fault. Structural map of the Maksimovskii seam in the southeastern part of the field of the Em. Yaroslavskii Mine (old). 1 — structure contours of the seam floor; 2 — a) hanging-wall, b) footwall truncation lines of the seam along the walls of disjunctives; 3 — minor disjunctives; 4 — mined-out areas of the seam; 5 — mine workings.

interstratal slip, and here it could have taken place chiefly at the expense of disjunctive dislocations.

The disjunctive faulting of the footwall block of the Zhurinskii thrust fault in the fields of the Zhurinka-3 and Em. Yaroslavskii mines is expressed somewhat differently (Fig. 1). Here there is a series of rather large apophyses of the Zhurinskii thrust fault. These include the SZh-1 thrust fault, which affects the northeastern limb of the Zhurinskaya anticline and dips to the southwest at an angle of 20–40°. The normal displacement amplitude along it in the field of the Zhurinka-3 mine reaches 25 m. A twisting of the displacer is observed, as well as an increase in its amplitude when moving northwestward.

In addition, nearly longitudinal disjunctives A–A and 1–1 have been recorded, dipping to the northeast at angles of 25–30° (Figs. 5, 6). Normal-

Fig. 5. Character of small disjunctives and fracturing in the footwall of the Zhurinskii fault. Sketch of faults in the face of longwall No. 14 of the Podzhurinskii seam: 1, 2 — shear angles; 3 — hidden fracture angle; 4 — aleurolite; 5 — bedding elements: numerator — azimuth of dip, denominator — dip angle; 6 — outlines of mine workings.

Fig. 6. Section of the seam in the footwall of disjunctive A—A. 1 — Sketch of the face of banded drift No. 23 (with a crosscut) of seam I of the Podzhurinskaya mine “Zhurinka-3” (symbols as in Fig. 5). 2. Schematic diagram of the bedding elements of systems of tectonic fractures in the area of the sketch: a — in coal, b — in the seam floor. 3. Detail of the footwall of the shear with hatching. The arrow indicates the direction of displacement of the hanging wall of the disjunctive.

the amplitudes of displacement along them reach, respectively, 100–130 m. Affecting the limbs and the hinge of the Egozovo syncline, these disjunctives change their form from an oblique to a conformable reverse fault. Dying out in the mine field of the Em. Yaroslavsky Mine, both disjunctives flatten out and converge, while displacement plane 1-1 splits, forming four disjunctives that disturb the Dal’nii seam at its outcrops beneath the overburden (Fig. 1). The spatial position of these displacement planes coincides rather closely with the attitude elements of longitudinal obliquely cutting systems of fractures. The dip direction of a displacement plane is determined by the prevailing dip of the strata that it affects and with which it is usually concordant.

Along with major ones, the Egozovo syncline is affected by a number of small disjunctives, among which the principal groups must be considered. The first group includes disjunctives occurring directly in the flanks of larger ones. This includes small disjunctives developed in the footwall of the Zhurinka reverse fault in the immediate vicinity of the displacement plane. In orientation and form of manifestation they are analogous to the disjunctives of the first group in the hanging wall of the Zhurinka reverse fault (Figs. 4, 5), differing from the latter in a considerably lower intensity of manifestation and an almost complete absence of transverse disjunctives. In the flanks of displacement planes A-A and 1-1, a number of small disjunctives have also been noted, represented by longitudinal conformable and oblique reverse faults, which are expressed much more clearly in the hanging flanks of the larger displacement planes.

The second group consists of disjunctives confined to second-order fold structures. This should include the conformable reverse faults, parallel to the fold axis, that occur on both limbs of the Zhurinka anticline. The dip angles of their displacement planes are 30–40°; the amplitudes of displacement along them are limited to three meters. Of particular interest is the group of direct thrusts that affected the northeastern limb of the Zhurinka anticline in the hanging wall of disjunctive SZh-1 (Fig. 7). Apparently, their amplitudes, as in SZh-1, increase toward the northwest. The formation of direct thrusts on fold limbs dipping in the direction of stress in a complex structural setting has already been noted in a number of areas of Kuzbass. The formation of disjunctives of this type in the present case should be associated with the twisting of the northeastern limb of the Zhurinka anticline, as well as with the proximity of the hanging cutoff of SZh-1, which created favorable conditions for the emergence of longitudinal oblique

Fig. 7. Direct thrusts on the northeastern limb of the Zhurinka anticline. 1 — mined-out portions of seams; 2 — mine workings.

faults whose displacers, when the limb was twisted, passed into a horizontal position and took the form of straight thrusts.

Disjunctives of the second group are widely represented in the areas of anticlinal bends of the axis of the Egozovo syncline, in places where transverse and differently oriented folds develop in the field of the Em. Yaroslavsky mine. Here mine workings have recorded a number of differently oriented disjunctives: subtransverse, diagonal, and longitudinal. In form these are concordant and discordant reverse faults and reverse strike-slip faults (Fig. 8) with insignificant displacement amplitudes.

The third, very small, group includes minor, locally developed disjunctives, the orientation of whose displacers does not

Fig. 8. Nature of the structure under conditions of an anticlinal bend of the axis of the Egozovo brachysyncline. Structural map of the Geolkomovskaya seams in the northwestern part of the field of the Em. Yaroslavsky mine. Symbols are the same as in Figure 4.

represent an exception to the general pattern, but they have no clear association with larger disjunctive or plicative forms. The displacement amplitude of the disjunctives of this group does not exceed 0.5 m.

In the footwall limb of the Zhurinsky reverse fault, as in the hanging wall, the spatial position of the displacers is controlled by obliquely intersecting fracturing and by the forms of plicative dislocations.

The general character of the tectonics of the mine fields in the northeastern part of the Leninsky district of Kuzbass shows that the formation of the structure here occurred under conditions of compressive stresses. The principal directions of compression were perpendicular and parallel to the axes of the main folds. The principal plicative structures of the district, longitudinal fracturing, and disjunctives owe their origin to the first; to the second—the bends of the axes of the main folds, transverse fracturing, and disjunctives. The structural forms named here clearly predominate in the area described. Such a structure could have arisen under uni-

lateral stress from the southwest, from the side of the Salair Ridge, when elongation along the axes of the main folds caused a reciprocal compressive reaction directed along the axis of the fold. This structure could have formed, as M. A. Usov [3] believed, also as a result of bilateral, mutually perpendicular stresses.

Summarizing what has been said above, the following may be noted:

1. The tectonics of the mine fields under consideration advantageously combines a significant volume of structural elements that are widely distributed within the Leninsky District of Kuzbass.

2. The difference between the principal plicative structures of the described area of the Leninskaya and Egozovskaya brachysynclines consists in the more complex character of the dislocations of the axis in the latter. As a result, within the Egozovskaya brachysyncline, additional folding has become widely developed, represented by more intense transverse undulation on the limbs and by variously oriented folds and flexures in the centriclinal parts of the principal fold.

3. The tectonic fracturing of coal seams and enclosing rocks is distinguished by the predominance of fractures of normal-crosscutting systems. Oblique-crosscutting fractures are clearly manifested in areas where additional folds and disjunctives have developed.

4. Disjunctive dislocations are developed rather widely within the mine fields under consideration, but they are not distinguished by great diversity. The attitude elements of their displacers tend toward two pairs of conjugate oblique-crosscutting systems of fractures (longitudinal and transverse to the axes of the principal folds). Localization of high-order disjunctives is observed on the flanks of larger ones, in particular the Zhurninsky thrust fault, and in places where additional folds of various types have developed.

5. As a result of the work carried out, it has been possible to establish, to some extent, the spatial and genetic relationship of additional folding with the structure of the principal folds, the genetic relationship of small disjunctives with oblique-crosscutting fracturing, and their spatial relationship with large disjunctives and additional folding. Taking this relationship into account, one can judge the presumed form of disjunctives in a given structural setting. Taking the established relationships into consideration, one may also raise the question of the possibility of predicting the character of the manifestation of small plicative structures in sections of mine fields, in areas of detailed exploration opened by mine workings, that are in tectonic conditions similar to those considered.

LITERATURE

1. A. A. Belitskii, On the development of a methodology for predicting the disturbed state of mine fields in Kuzbass. “Questions of the Geology of Kuzbass,” vol. 2, Tomsk University Press, Tomsk, 1959.

2. A. A. Belitskii and E. M. Pakh. Regularities of the tectonic structure of the Kuznetsk Basin. In: “The Fundamental Ideas of M. A. Usov in Geology,” Publishing House of the Academy of Sciences of the Kazakh SSR, Alma-Ata, 1960.

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