ON THE ISSUE OF THE GEOLOGICAL AND INDUSTRIAL CLASSIFICATION OF KUZBASS DEPOSITS

L. M. PETROVSKY

(Presented by the Department of Geology and Exploration of Mineral Deposits)

The principal geological-exploration indicators of industrial types of coal deposits for any of their genetic groups, as is known [2], are: 1) the geological characteristics of coal seams—their form, structure, and persistence; 2) tectonics. Under the conditions of exploration of Kuzbass deposits, the tectonic feature acquires exceptional importance, since it is precisely tectonics that has manifested itself in the greatest diversity in its deposits.

Until comparatively recently, the basis for the industrial classification of coal deposits according to exploration conditions was taken to be entire coal basins, in all the diversity of their individual parts [1]. However, even at that time the exploration of individual deposits in Kuzbass, for example, was carried out practically in accordance with the specific features of their tectonic structure. Later, at the conference on questions of the geology of Siberia held in Tomsk in 1957, the geologists of the Kuzbassuglegeologiya trust presented a generalized geological-industrial classification of Kuzbass deposits [4]. This made a significant contribution to the selection of a rational methodology for exploring individual deposits in so structurally diverse a basin. Similar work was carried out in the Karaganda (E. O. Pogrebitsky, 1956), Pechora (V. N. Volkov, 1958), and other major basins of the country. These served as the basis for a unified revised geological-industrial classification of coal deposits [2]. All Kuzbass deposits, according to this classification, as well as according to the classification of the Kuzbassuglegeologiya trust, are combined into 3 types, which, however, are characterized by a number of differences from one another (Table 1). Above all, the designation of an independent type, “gentle monoclines,” seems incorrect to us, since in essence a monocline is ultimately the limb of a fold. In this respect, the definition of the first type of deposits in P. V. Vasil’ev’s classification appears more acceptable. In connection with this, it would be rational to combine the first and part of the second types of E. M. Pakh’s classification, as was done in P. V. Vasil’ev’s classification. In this type of deposits it would then be advisable to distinguish 2 subtypes instead of the first 4 subtypes proposed by E. M. Pakh: the 2 subtypes distinguished in each of the first 2 types of deposits differ from one another only in the degree of their closure and, apart from complicating the classification, do not provide particular clarity.

According to E. M. Pakh, E. M. Sinyerezov, 1959 | Table 1 | According to P. V. Vasiliev, 1960

*) The first and second figures are recommended respectively for stable and relatively stable seams.

introduce. On the other hand, the identification of 3 subtypes in the last type of deposits in E. M. Pakh’s classification is of unquestionable value.

The recommendation in E. M. Pakh’s classification to explore the first working horizon of mine fields with a denser network of boreholes deserves attention. Unfortunately, it must be stated that exploration of areas during the past period was carried out practically without regard to differentiation of the network and borehole depths by horizons. At least for the first 3 horizons, in most of the areas of this period of work, not only the density of exploration lines but also the degree to which they were explored proves to be the same. In a number of cases, however, the degree of exploration of the first working horizon for detailed exploration proves to be considerably lower than for the lower ones.

Despite the progress achieved by both of the geological-industrial classifications of Kuzbass deposits considered, they still do not eliminate the principal shortcoming that, in almost every one of the identified types or subtypes of deposits, there are areas characterized by different exploration conditions. Thus, for example, in the Osinovka district of Kuzbass, areas located on the western limb of the Shelkan syncline have a complex and very complex structure, while areas located on its eastern limb have a simple structure. Thus, for the purpose of typifying areas according to uniform methods and conditions of exploration, the need for a more detailed classification of them within individual deposits is evident. For the first time in Kuzbass, such a classification was carried out by V. Ya. Koudelny [3] for areas and mine fields of the Prokopyevsk-Kiselevsk district, where 3 types of them were distinguished. Below the necessity of a similar classification of exploration areas in the Baidaevka district will be shown, as one of the deposits of the type of simple folded structures.

A brief geological-industrial characterization of the Baidaevka deposit is as follows. Stratigraphically, its coal-bearing deposits belong to the Ilyinskaya and Erunakovskaya suites of the Kolchuginskaya series. The underlying Ilyinskaya suite is commercially coal-bearing only in its upper part, belonging to the Uskat sub-suite. The latter, in turn, is commercially coal-bearing only in the western part of the district (areas 1, 5, 9), while in the central and northeastern parts it is commercially coal-bearing only in the upper half (coal seams No. 14–25). In the west of the district, the average thickness of the Uskat sub-suite is 800 m, and of the 25 coal seams No. 1–25, up to 19 workable seams are counted here, with thicknesses from 0.7 to 1.65 m. The average workable coal content of the sub-suite is 2.7%; the coals are coking, fat, and gas-fat.

The Erunakovskaya suite is represented only by its lower part—the Leninskaya sub-suite, the greatest exposed thickness of which in the center of the syncline (areas 7, 8, 9, 10) is 570 m. Of the exposed 18 coal seams No. 26a–38, the number of workable seams varies from 11 to 14, with thicknesses from 0.8 to 4 m. The average workable coal content of the Leninskaya sub-suite is 3.8%. The coals are gas coals: those of the lower seams are coking, those of the upper seams—power-generating.

In general, for the district there is an overall increase in the number of seams in the northeastern direction, with a simultaneous decrease in the number and thickness of workable seams.

The tectonics of the areas is determined by their position relative to the main structure of the district—the Baidaevka syncline, open to the north. Within the latter, three brachysynclines are distinguished. The largest—the Baidaevka—is located in the southern part of the synclina-

[[unclear: beginning of line]] and is characterized by a nearly meridional strike of the long axis. It is marked by pronounced asymmetry, with a steep (up to \(70^\circ\)) western limb (areas 1, 5) and a gentle (\(10—25^\circ\)) eastern limb (areas 2, 3, 4); both limbs are characterized by persistent elements of bedding of the rocks.

The Esaul brachysyncline, next in size, is located in the northeastern part of the syncline and is characterized by a nearly latitudinal strike of its long axis. On its southern limb lie areas 8, 10 (area 6 is located on the eastern limb of the syncline between the Baidaev and Esaul brachysynclines). Because of the differently oriented structural position of the coal-bearing sequence on the southern limb of the Esaul brachysyncline—latitudinal strike of the upper group of seams and northeastern strike of the middle (\(24—29\,d\)) and lower (\(14—16\)) groups—a clear differentiation of dip angles is observed here: nearly horizontal occurrence of the upper group of seams, \(25—40^\circ\) for the middle group, and \(10—15^\circ\) for the lower group.

The smallest, the Antonov brachysyncline, is situated in the northwest of the district and is characterized by a northeastern strike of its long axis. It, as with the Esaul brachysyncline, is marked by a noticeable variability in the bedding elements of the seams, whose dip angles vary from 3 to \(40^\circ\).

Table 2

The folded structures described are affected to varying degrees by disjunctive faults. The largest disjunctive fault within the Baidaev brachysyncline is the conformable reverse fault B on its eastern limb. Having a maximum displacement amplitude (up to 100 m) in the south, within area 2, it can be traced along its entire eastern limb, dying out within the Esaul brachysyncline, in area 8. This disjunctive fault is the natural boundary of the field of the Zyryanovskaya mine and of the fields of the Abashevskaya 1—2 and Abashevskaya 3—4 mines, and so far has caused no complications in mining. Smaller disjunctive faults on the limbs of the Baidaev brachysyncline are rare. One of them is the conformable reverse fault A, with a displacement amplitude of up to 30 m, intersected by boreholes and later confirmed by mine workings in the field of the Abashevskaya 3—4 mine. Small ruptures with displacement amplitudes of up to 15—10 m were noted locally in the fields of the Baidaevskaya 1—2 and Abashev mines.

Within the Esaul and Antonov brachysynclines, on the contrary, according to boreholes in areas 8, 9, 10, and 11, a number of disjunctive structures with displacement amplitudes of up to 50–100 m and more have been intersected.

Thus, in terms of the complexity of tectonic structure, two groups are clearly outlined among the areas of the Baidaevka district: those characterized by relatively simple (areas Nos. 1–7) and by more complex

Fig. 1. Comparison of specific footage costs (indicator P) for detailed exploration and supplementary exploration of areas with the degree of exploration achieved for them: 1 — areas of simple geological structure and the comparison curve for them; 2 — areas of complex geological structure and the comparison curve for them; 3 — area numbers and values of the average working-coal-content coefficient for them. Names of areas: 1 — Baidaevka 1–2; 2 — Zyryanovka; 3 — Abashevo 1–2; 4 — Abashevo 3–4; 5 — Baidaevka 3–4; 6 — Esaul 1–2; 7 — Baidaevka Eastern 1–2–3; 8 — Esaul 3–4; 9 — Antonov 1–2; 10 — Esaul 5; 11 — Antonov 3.

(Nos. 8–11) exploration conditions. To confirm this, let us compare the principal technical-and-economic indicators of the detailed explorations and supplementary explorations carried out in 11 areas of the Baidaevka district (Table 2).

The comparison reveals two sharply different groups, in one of which (areas Nos. 3, 4, 5, 8, 9, 10, 11) the costs of borehole footage (for the reduced areas) turn out to be two or more times higher than in the other (Nos. 1, 5, 6, 7). At the same time, in areas 3, 4, and 5, which on the basis of geologic-structural analysis belong to the group of simple structure, because of an incorrect work methodology the costs of borehole footage in fact correspond to the costs for areas of complex structure,

Taking into account the foregoing observation, the proposed grouping of tracts in the Baidaevsky district can be clearly represented graphically in the form of two curves comparing the specific costs of drilling meterage per 1,000 tons of reserves in categories A+B (indicator II) and their degree of exploration (Fig. 1). From the position of the minimum values of the specific meterage costs on the obtained comparison curves, it may be concluded that tracts of simple structure (A) should not be explored to a degree of exploration above 75%, and those of complex structure (B)—65%.

The example given convincingly shows how different the volumes of work for the exploration of tracts may be, even in what would seem to be such a tectonically simple Baidaevsky district of Kuzbass.

REFERENCES

1. P. V. Vasiliev. Evaluation of Deposits in Prospecting and Exploration. Issue 5. Coal. Gosgeoltekhizdat, 1949.

2. P. V. Vasiliev. Evaluation of Deposits in Prospecting and Exploration. Issue 5. Coal. Gosgeoltekhizdat, 1960.

3. V. Ya. Koudelny. On the methodology of exploration of coal deposits. Razvedka i okhrana nedr, No. 5, 1957.

4. E. M. Pakh, E. N. Snegirzon. The density of the detailed-exploration network and the testing of coal deposits in Kuzbass. Problems of the Geology of Kuzbass, vol. 2, 1959.