NEW DATA ON THE GEOLOGY OF THE ZALOMENSKY AND VERKHNETERSINSKY DISTRICTS OF KUZBASS

V. I. BUDNIKOV

The eastern part of the Kuznetsk Basin is of great interest because within its limits there are a number of coal deposits: the Zalomensky, Zmeinsky, Tutyas-Cheksinsky, Makarievsky, and others.

This district deserves no less attention with regard to the prospects for oil and gas potential, owing to the presence in it of:

a) possible oil-source deposits within the Middle and Upper Devonian and marine Lower Carboniferous;

b) numerous finds of primary and secondary bitumens, some of them of unquestionably petroleum origin, in Devonian and marine Lower Carboniferous deposits in the area of the Barzas uplift and the Krapivinsky dome, as well as finds of petroleum-like substances and oil in coal-bearing deposits (the area of the village of Uzuntsy);

c) good porous reservoirs (the Alykayevskaya, Intermediate, and Ishanovskaya subformations in the area of the Zalomensky depression);

d) structural forms of the brachyanticline and dome type (Verkhnetersinskaya, Cheksinskaya, and a number of structures in the area of the Zalomensky depression);

e) favorable hydrogeological indicators.

All this indicates the possibility of discovering oil and gas fields here (Budnikov and Petrov, 1957).

In addition, the possibility cannot be excluded of discovering, in the eastern part of Kuzbass—whose supply area in Middle–Upper Paleozoic time was mainly the Kuznetsk Alatau—hypergene deposits of metals.

Nevertheless, the eastern part of Kuzbass still remains poorly studied, and this is explained primarily by the difficult accessibility of this territory (taiga character, swampiness of the area, absence of roads, etc.).

In connection with the forthcoming expansion of prospecting and exploration work in the basin of the Upper Ters River and within the Zalomensky depression, the clarification and detailing of stratigraphic schemes for these districts are becoming of great importance.

Possessing considerable factual material collected over the last three years by the Zalomensko-Verkhnetersinsky party of the Siberian Branch of VNIGRI, as well as material obtained as a result of studying cores from wells drilled by the trust “Zapsibneftegeologiya” and by the West Siberian Geological Administration, I have considered it necessary to report some new data, mainly concerning questions of stratigraphy, and to show the effectiveness of applying cyclic and lithologic-pet—

rographic methods (used in combination with other methods, primarily biostratigraphic ones) in subdividing and correlating sections of coal-bearing deposits in the eastern part of Kuzbass.

Geological Structure of the Zalomenskaya Depression

The Zalomenskaya depression is a large synclinal structure located in the northeastern part of Kuzbass between two large and complexly built anticlinal uplifts: the Barzas uplift in the north and the Krapivinsk uplift in the south. From the northeast the Zalomenskaya depression is bounded by the Kamzhal monocline of the Kuznetsk Alatau; toward the southwest it is open in the direction of the Kemerovo syncline.

The generally monoclinal western and southwestern dip of the beds within the depression is complicated by a number of second-order structures of the brachyanticline and structural-nose type, identified mainly as a result of geological mapping in 1940–1943 by the Krapivinsk–Zalomenskaya and East Kuzbass expeditions of the West Siberian Geological Exploration Trust of the People’s Commissariat of the Oil Industry of the USSR under the direction of S. F. Petukhov. These are the so-called Zalomenskaya, Gryaznenskaya, Verkhnegryaznenskaya, Kuchumovskaya, Rudnikovskie, and other anticlinal structures (the Nizhnegryaznensk uplift was not confirmed by drilling carried out in 1956 by geologists of the “Zapsibneftegeologiya” Trust, F. K. Salmanov and A. I. Lezhnin).

The coal-bearing deposits filling the Zalomenskaya depression are represented by the Balakhon Series; only in the extreme western part of the depression are rocks of the Kuznetsk Formation developed (Fig. 1).

Within the depression the Balakhon Series has been penetrated by three profiles of wells drilled by the Zmeinsk geological exploration party of the West Siberian Geological Administration in the area of the village of Zmeinka; an almost complete section of this series was obtained by the Nizhnegryaznensk oil-exploration party of the “Zapsibneftegeologiya” Trust in the basin of the lower reaches of the B. Gryaznaya River; a new section of the Balakhon Series was opened on the Voskresenskaya site by the deep exploratory well R-1; the middle horizons of the series were penetrated by wells 5k, 6k, and 7k in the area of the Zalomenskaya uplift.

In addition, the coal-bearing deposits within the Zalomenskaya depression have been exposed by a large number of mine workings.

Good outcrops of the upper part of the Balakhon Series and of the Kuznetsk Formation occur on the right bank of the Tom River in the interval from the mouth of the B. Gryaznaya River to the mouth of the Spuskovaya River.

On the basis of analysis of flora and fauna, spore-and-pollen complexes, and lithological features of the rocks, with the application of cyclic analysis, the deposits of the Balakhon Series have been subdivided into the Ostrog, Lower Balakhon, and Upper Balakhon formations; the latter, in turn, are divided into subformations (Fig. 2).

The Ostrog Formation \((C_1^3)\) in the area under consideration is represented by two facies complexes: a complex of shallow-water marine facies in the southwestern part of the Ermakovskaya area, the Voskresensk district, and the western part of the Zalomenskaya depression, lithologically expressed by a thick aleurite–argillite unit containing abundant marine fauna; and a complex of continental facies in the northeastern part of Ermakov, the Kuchumovsky district, the Krapivinsky dome, and the eastern part of the Zalomenskaya depression, composed mainly of sandstones and conglomerates with packets of clayey rocks in the middle part of the section and with coal interbeds in the upper part.

At the base of the formation in the Rudnikovsky district and over most of the Ermakovskaya area, a bed of basal conglomerates and deposits can be traced—

LEGEND

• Kuznetsk Formation
• Usyat–Kemerovo Subformation
• Ishanovo Subformation
• Intermediate Subformation
• Alykaevo Subformation
• Mazurovo Subformation
• Ostrog Formation
• Stratigraphic boundaries
• Axes of anticlines
• Axes of synclines
• Tectonic faults

Scale: km 0 1 2 3 4

Fig. 1. Schematic geological map of the Zalomnaya Depression of Kuzbass. Compiled by V. I. Budnikov from materials by V. D. Fomichev, S. F. Petukhov, P. A. Stepanenko, F. K. Salmanov, G. I. Sazhnev, A. I. Lezhnin, and V. I. Budnikov, 1957.

there is observed erosion of the Visean deposits, up to their complete disappearance from the section of the Verkhotomskaya zone.

This boundary has an entirely different character in the area of the Krapivinsky dome, as well as in individual parts of the Ermakovo area (boreholes 11, 13, 28, 29), where conglomerates at the base of the Ostrog Formation are absent, and gradual, imperceptible transitions without any traces of a break are observed between the Visean deposits and the Ostrog Formation.

These data show that the pre-Ostrog break was of short duration and not universal. The marine fauna collected in the Ermakovo area, according to the determinations of many researchers, characterizes the Lower Carboniferous, more precisely the Upper Visean—Namurian age of the enclosing beds [2].

The collection of Ostrog fauna has now been supplemented by material from deep borehole R-1 in the Voskresenskaya area. Here a core and imprint of Leda attenuata Flem., two specimens of Chonetes shunardiana Kon. (depth 1820—1822 m), one imprint of a goniatite, one imprint of a bryozoan, and one gastropod core were encountered. V. A. Lapshina, who is studying this fauna, concludes that it is analogous to the Ermakovo fauna. From the same borehole, R. N. Benediktova identified a rather large incomplete core and imprint of Athyris sp. (depth 1796.6—1799.9 m) and two imprints of Conularia sp. (depth 1815—1823 m).

The upper boundary of the Ostrog Formation is placed 75 m below the Dyuryagin bed in the Zmeinka section (Budnikov and Petrov, 1957).

The thickness of the formation in the area of the Krapivinsky dome is 200 m; in the Voskresenskaya area, according to B. N. Pyankov, it is 275 m; in the Ermakovo area, 450 m.

The Lower Balakhonka Formation \((C_{2-3}^{b1})\) lies conformably on the deposits of the Ostrog Formation and is subdivided into the Mazurovka and Aldykaevo subformations.

The Mazurovka Subformation of the Zalomenskaya depression is characterized by an alternation of sandstones, siltstones, coaly argillites, and coals (with limestone interbeds in the Kuchumovo area), by the presence in the section of thick packets of interbedded siltstones and argillites, by the gray and light-gray coloration of the sandstones, by the presence of 13 coal seams of workable thickness, the number of which increases upward through the section, and by thin cycles of sedimentation of the third order in the upper part of the subformation¹).

The amount of sandstone increases somewhat from west to east on approaching the Kuznetsk Alatau; in the same direction the coal-bearing character diminishes, and the gray and light-gray coloration of the sandstones gives way to greenish coloration.

From the Mazurovka Subformation of the Zmeinka section, S. G. Gorelova and N. P. Burova collected a fauna in which brachiopods (the genera Chonetes and Lingula) predominate quantitatively; this, in the opinion of R. N. Benediktova, indicates a higher salinity of the Mazurovka basin in the Zmeinka area as compared with other basins of Kuzbass at that time.

Paleobotanically, the Mazurovka Subformation of the Zalomenskaya depression is characterized by the following forms: Angarodendron Obrutchevii Zal., Neuropteris izylensis (Tchirk.) Neub., Angaridium submongolicum Neub., Noeggerathiopsis subangusta Zal., Gondwanidium petiolatum Neub.

The upper boundary of the subformation is drawn at the base of a large cycle of the second order, in the lower part of which lies a thick packet of Zmeinka—

¹) The characterization of cycles of different orders is given at the end of the article.

sandstones, in which G. P. Radchenko found Noeggerathiopsis batschatensis Radcz., not occurring in the Mazurovo subformation. The thickness of the Mazurovo subformation in the southern part of the depression is 325 m.

The Alykaevo subformation is characterized by a predominance in the section of fine-grained sandstones (the grain size increases from west to east within the depression), by the gray and light-gray color of the sandstones and siltstones (green coloration predominates in the lower part of the section in the western part of the depression and throughout the section in the Pri-Alatau belt), by the presence of four coal seams of workable thickness, grouped two by two in the middle and upper parts of the subformation, and by two large second-order cycles of sediment accumulation, at whose boundaries washouts are recorded.

The Alykaevo subformation is well characterized by flora and fauna. It is characterized by the so-called Alykaevo fauna [3], the first representatives of which appear already in the Mazurovo subformation. From the Alykaevo subformation of the Zmeinka district, R. N. Benediktova identified Kinerkaella balakhonskiensis (Rag), Mrassiella magniforma Rag., Cirratus jaworskii Chern. among malacostracan crustaceans, and worms of the genus Spirorbis.

The absence in this fauna of brachiopods and pelecypods of marine aspect indicates, in the opinion of R. N. Benediktova, that the deposits of the Alykaevo subformation of the Zmeinka district were formed in a basin with lower water salinity than the deposits of the Mazurovo subformation, but nevertheless considerably higher than in other Kuzbass basins of that time.

Elements of the first Alykaevo fauna have been encountered in the Lower Balakhonka formation of the Voskresensk section. Here, according to R. N. Benediktova, Chonetes sp. and Dielasma sp. are present (the first find in the Balakhonka series of Kuzbass).

Among plant remains, according to S. V. Sukhov, the following are characteristic of the Alykaevo subformation of the Zalomnaya depression: Angaropteridium cardiopteroides (Schm.) Zal., Gondwanidium sibiricum (Petunn.), Tchirkoviella sibirica Zal., Noeggerathiopsis batschatensis Radcz., N. Theodori Tschirk. et Zal., Sphenopteris izylensis Zal., Samaropsis zalominskiensis Such., Angarocarpus ungensis Zal., Cordaicarpus pauxilla Zal.

The upper boundary of the subformation is drawn at the disappearance in the section of the fauna and floristic assemblages at the base of a large second-order cycle of sediment accumulation, represented chiefly by medium- to coarse-grained sandstones with interbeds of gravelites and conglomerates (on the Nizhnegryaznaya area this boundary passes several meters above the Opolznevo seam; in borehole 7k in the area of the Zalomnaya structure, at a depth of 225 m; in Voskresensk borehole R-1, according to B. N. Pyankov, at a depth of 964 m).

The thickness of the Alykaevo subformation in the area of the Bolshaya Gryaznaya River is 166 m, on the Voskresensk area—210 m, and in the area of the Zalomnaya uplift—more than 215 m.

The Upper Balakhonka formation \((P_1^{bl})\) is represented by a sandy-clayey coal-bearing complex of rocks, within which the Intermediate, Ishanovo, and Usyat-Kemerovo subformations are distinguished.

The Intermediate subformation is characterized by a clear predominance in the section of medium- and coarse-grained sandstones with interbeds of gravelites and conglomerates (80% of the section), by gray and gray with a brownish tint coloration of the sandstones and siltstones, by two second-order cycles of sediment accumulation, at whose boundaries there are washouts, and by extremely weak coal content (the subformation contains one coal seam of worka-

Scale: +20, 0, 20, 40, 60, 80 m

Visible column headings in the stratigraphic columns: suite, subsuite, lithology, cyclothem, number of coal-bearing horizon, seam no.

Visible stratigraphic and bed labels include: Kuznetsk suite; Usyatsko-Kemerovo subsuite; Ishanovo subsuite; Kazankovo subsuite; Mitino subsuite; Promezhutochnaya subsuite; Alynkaevskaya subsuite; Mazurovo subsuite; Ostrógskaya subsuite; Balakhon suite; Nizhnebalakhon suite; Kardynatovsky; Poryvaevsky I; Poryvaevsky II; Poryvaevsky (39); Upper (38); Middle (37); Lower (36); Molodezhny (33); Opolznevoi (32); Beregovoi; Tomsky; Tomsky; Korshunov (27); Georgievsky; Dyadinsky; Zakharovsky.

Fig. 2. Composite section of the Balakhon Series and the Kuznetsk Formation of the southern side of the Zalomnaya depression. Compiled by V. I. Budnikov using materials of F. K. Salmanov, A. I. Lezhnin, A. V. Kutukov, and P. A. Stepanenko.

1 — conglomerates; 2 — coarse-grained sandstones; 3 — medium-grained sandstones; 4 — fine-grained sandstones; 5 — siltstones; 6 — argillites; 7 — carbonaceous argillites; 8 — coal; 9 — flora; 10 — fauna; 11 — breaks in sedimentation.

working thickness—the Molodezhnyi), by the complete absence of fauna and an extremely poor composition of the leaf flora.

The upper boundary of the subsuite is drawn provisionally at the base of a large second-order sedimentation cycle, which rests with erosion on rocks that we assign to the intermediate subsuite.

The thickness of the intermediate subsuite in the southern part of the depression is about 100 m; in the area of the Zalomnenskoe uplift, 150 m.

The Ishanovskaya subsuite is characterized by the presence of a large number of siltstone and argillite beds (one third of the section); by a large number of coal seams, concentrated mainly in the upper parts of the subsuite; by the gray and dark-gray coloration of the sandstones; by two large second-order sedimentation cycles; by the complete absence of fauna; and by a poor floristic assemblage.

The upper boundary of the Ishanovskaya subsuite is drawn several meters above the Poryvaevskii 1 seam—the first coal seam from the top of workable thickness in the Balakhon Series—at the base of a second-order cycle that rests with erosion on the underlying rocks and is composed almost entirely of sandstones.

The thickness of the Ishanovskaya subsuite in the area of the Bolshaya Gryaznaya River is 180 m.

The Usyat-Kemerovo subsuite is represented by light-gray and yellowish-gray sandstones with interbeds of gravelites and gravel conglomerates, abundant pebbles of sedimentary rocks, fragments, trunks, and entire horizons of petrified wood. Sandstones make up 80% of the section. The subsuite contains six coal seams, most of them of nonworkable thickness.

The floristic assemblage of the Usyat-Kemerovo subsuite is poor; fauna occurs as isolated specimens.

The thickness of the subsuite in the western part of the depression is 245 m.

The Kuznetsk suite \((P_1^{k})\). The boundary between the Upper Balakhon and Kuznetsk suites and, consequently, between two large first-order cycles of sedimentation and coal accumulation—the Balakhon and Kolchugino—is drawn at the base of the horizon of basal conglomerates exposed on the right bank of the Tom River at the mouth of the Poryvaika River, and also in the crest of the Poryvaika anticlinal fold.

The upper boundary of the Balakhon Series is not only lithological but also biostratigraphic; at this level the freshwater Late Balakhon fauna is replaced by the so-called Early Kuznetsk fauna [4]. An assemblage of Early Kuznetsk fauna, with its characteristic brackish-water elements (the genera Mrassiella and Augea), has been encountered in the lower parts of the Kuznetsk suite of the Voskresensk district.

In the northeastern part of Kuzbass, the Kuznetsk suite is subdivided on lithological grounds into three parts (in the lower part, clayey rocks are predominant; in the middle part, fine- and medium-grained sandstones; the upper part is likewise represented by sandstones, among which there are packets of siltstones and argillites). In the opinion of I. A. Vyltsan, these correspond to the Usinsk, Kuznetsk, and Mitinsk horizons distinguished in the Kuznetsk suite in the south of the basin by Yu. A. Zhemchuzhnikov [1].

In the lower part of the suite there are two beds of variegated rocks, represented by argillites and siltstones. These beds are exposed on the right bank of the Tom River in the area of the village of Poryvaika, in the basin of the Mungat River, and have been penetrated by wells on the Voskresensk and Borisov areas (Kutyukov, 1954); owing to their bright coloration and persistence, they are good marker horizons in the Kuznetsk suite of the northeastern part of Kuzbass.

The upper boundary of the suite is drawn along the base of a uniform sequence of Krasnoyarsk sandstones.

The thickness of the Kuznetsk suite in the area of the Zalomenskaya depression is 510 m.

Geological Structure of the Verkhnetersinsky District

The Verkhnetersinsky district is a large brachyanticlinal-type structure, broken by a series of faults of NW strike and NE dip into a number of blocks thrust over one another along these faults from east to west.

In the crest part of the structure, deposits of the Balakhon series crop out (the Makar’evskoe coal deposit); the limbs and periclinal parts of the structure are composed of rocks of the Kuznetsk and Ilyinsk suites. The size of the structure along the top of the Upper Balakhon suite is 16 × 4 km.

The SW limb of the Verkhnetersinsky structure is complicated by a number of additional uplifts of the brachyanticlinal type. Such an uplift, in particular, was identified as a result of work by the Tutuyasskaya party of the West Siberian Geological Administration in the basin of the Malyshikhi River.

A fairly large anticlinal flexure was established by us on the right bank of the Upper Ters River in the area of the mouth of the V. Maganakova River. This flexure, in all probability, corresponds to the periclinal part of a large anticlinal structure (named by us the Osinovskaya), situated in the left-bank part of the lower course of the V. Ters River, between the Erunakovskaya and Ostashkinskaya synclines. Whether the Osinovskoye uplift is an independent structure or represents part of the Verkhnetersinsky uplift—in either case it is of great interest for oil geologists.

Deposits of the upper half of the Balakhon series are exposed in the basin of the V. Ters River by a profile of core boreholes and by a large number of mine workings of the Tutuyasskaya party of the West Siberian Geological Administration; deposits of the Kuznetsk and Ilyinsk suites crop out along the banks of the V. Ters River, beginning from the village of Osinovoe Pleso to the mouth of the Voskresenka River, over a distance of 45 km.

Lower Balakhon suite \((C^{b1}_{2}—C^{b}_{2-3})\). The middle horizons of the Lower Balakhon suite in the area of the Makar’evskoe deposit were exposed by borehole 4k of the first profile of the Tutuyasskaya party. The exposed part of the Lower Balakhon suite (175 m) is characterized by a clear predominance of siltstones in the section, the presence of packets of fine-grained sandstones, the light-gray color of the latter, very weak coal content (two coal beds 0.2 m thick each were noted), and an almost complete absence of organic remains (there is one layer with imprints of flora of very poor preservation). The rocks are broken by numerous fractures filled with calcite. In the core, a mass of microfaults is observed, as well as a sharp change in the angles of dip of the beds relative to the core column. All this indicates that borehole 4k intersected a fault.

The lower and upper boundaries of the suite were not exposed by boreholes.

Upper Balakhon suite \((P^{b1}_{1})\), with a total thickness of 855 m, is characterized by a predominance of sandstones with interbeds of gravelites and conglomerates in the lower part of the section and an alternation of sandstones and clayey rocks in the upper part. In the middle part of the suite there is a bed of quartz diabases 100 m thick. The suite contains 23 coal seams, most of which reach workable thickness, and some (seams XII and XVI) are 6–7 m thick (Fig. 3).

Paleobotanically, the Upper Balakhon suite in the area of the Upper Ters River is characterized relatively poorly, although considerably better than in the NE part of the basin. Six floristic horizons have been noted in it...

Fig. 3. Section of the Upper Balakhon Formation of the Verkhnetersinsky district of Kuzbass.
Compiled by V. I. Budnikov.
Legend—see Fig. 2; 9—diabases.

horizons, characterized, according to S. G. Gorelova, by the following forms: Annularia Neuburgiana Radcz., Noeggerathiopsis cf. Derzavinii Neub., Nephropsis rhomboidea Neub., Neuropteris cf. pulchra Neub., Crassinervia kuznetskiana (Chachl.) Neub., Noeggerathiopsis Theodori Tschirk. et Zal., N. latifolia Neub., Sphenopteris imitans Neub.

In the upper part of the suite (borehole 8k, depth 64.5 m), two indeterminate impressions of rather large pelecypods were encountered.

The upper boundary of the Upper Balakhon suite is drawn in the area of the V. Ters’ River along the base of the conglomerate horizon, which lies 30 m above seam 1—the first coal seam from the top of the Balakhon series.

The Ishanovo–Intermediate subsuite is characterized by a predominance of thick packets of medium-coarse-grained sandstones with interbeds of gravelites and conglomerates; by gray, greenish-gray, and brownish-gray coloration of the sandstones and conglomerates; by the presence of nine coal seams of workable thickness; and by four large second-order sedimentation cycles, at the boundaries of which erosional surfaces are noted.

The upper boundary of the subsuite is drawn along the roof of seam XII at the base of a large second-order sedimentation cycle.

The thickness of the exposed part of the Ishanovo–Intermediate subsuite (in all likelihood, the entire or almost the entire subsuite has been exposed) in the area of the Upper Ters’ is 415 m.

The Usyatsko–Kemerovo subsuite is represented by a uniform alternation of sandstones, siltstones, carbonaceous argillites, and coal seams. It contains 14 coal seams of workable thickness, generally distributed evenly through the section. In the lower part of the subsuite, as noted above, a bedded occurrence of quartz diabases 100 m thick has been exposed.

The lower and middle horizons of the subsuite studied by us in detail (300 m) constitute a single second-order sedimentation cycle divided into 5 third-order cycles.

The thickness of the Usyatsko–Kemerovo subsuite in the area of the Makaryevka deposit is 440 m.

The Kuznetsk suite ($P^{k}_{2}$), possibly with an erosional break (conglomerates are noted at the base of the suite only at one point—in borehole 10k), lies upon the deposits of the Balakhon series. It is represented mainly by sandstones; packets of clayey rocks are noted in the lower and upper parts of the section.

The sandstones are gray, gray with greenish and brownish shades, from fine- to coarse-grained (the coarsest-grained varieties are noted in the middle part of the section), and very dense.

Within the subsuite, two second-order sedimentation cycles are conditionally distinguished.

The Kuznetsk suite of the Upper Ters’ district does not have its own independent floristic assemblage, and no fauna has yet been found in it.

Characteristic of the suite is an increased zircon content in the heavy fraction of the sandstones (usually more than 13%) in comparison with the sandstones of the Balakhon series, where zircon in the heavy fraction amounts in most cases to no more than 10%.

The thickness of the Kuznetsk suite in the area of the V. Ters’ is 800 m.

The Ilyinskaya suite ($P^{il}_{2}$). Above, without any traces of a hiatus or unconformity, lies a thick unit of sandy-clayey deposits of the Ilyinskaya suite. The latter is represented by frequent interbedding of sandstones, siltstones, and argillites with interbeds of spherosiderites, and also

clayey varieties of rocks make up more than half of the section. Coal-bearing interbeds and coal seams have been encountered in the suite; their thickness reaches 1.4 m.

The suite is characterized by the presence of thick packets of fine interbedding of siltstones and argillites containing thin beds of spherosiderites (the thickness of these beds is 1–3 cm, the distance between them 5–10 cm). The spherosiderites are light brown, brown, and yellowish in color and stand out clearly against the general dark-gray background of the clayey rocks, so that the sequence acquires a characteristic banded structure.

Within the studied 900-meter thickness of the Ilyinskaya suite, 10 cycles of the second order have been distinguished, which, in turn, are subdivided into 59 cycles of the third order. The number of cycles will undoubtedly increase when a complete section of the suite is obtained.

Characteristic of the suite is the very small thickness of the cycles of the third order, equal, as a rule, to 5–10 m, in most cases 6–8 m.

The suite contains several beds with abundant pelecypod fauna which, in the opinion of O. A. Betekhtina, is typical of the Ilyinskaya suite: Abiella concinna (Jones), Anthraconauta obliqua (Khalf.), A. simplex (Khalf.), A. pseudophillipsii Fed., A. tchernychevi (Khalf.), Microdontella subovata (Jones), Anthraconauta iljinskiensis Fed.

In these same horizons there are also ostracods which, according to M. A. Reshetnikova, are characteristic of the Ilyinskaya suite. Plant remains occur rather rarely and are represented by forms that have a very wide vertical distribution. In connection with the absence of fauna in the upper horizons of the Kuznetsk suite, the lower boundary of the Ilyinskaya suite in the Verkhnetersinsky district is drawn at the beginning of the fine interbedding of rocks containing coal interlayers.

The total thickness of the Ilyinskaya suite in the Verkhnetersinsky district is 1150 m. The upper boundary is drawn rather conventionally at the base of a thick sequence of medium-grained sandstones lying with erosion on the underlying rocks.

The Role of Cyclic and Lithologic-Mineralogical Analyses in the Subdivision and Correlation of Sections of Coal-Bearing Deposits in the Eastern Part of Kuzbass

Within the coal-bearing deposits of the Zalomenskaya depression and the Verkhnetersinsky district, as in other districts of Kuzbass, alongside sequences that are well characterized paleontologically (the marine facies of the Ostrog suite, the Nizhnebalakhonskaya suite, and the lower part of the Kuznetsk suite of the Zalomenskaya depression), individual parts of the section either contain no organic remains or contain them in insignificant quantities (the Promezhutochnaya, Ishanovskaya, and Usyatsko-Kemerovskaya subsuites of the Zalomenskaya depression, and the Nizhnebalakhonskaya suite of the Verkhnetersinsky district). In addition, some floristic and faunistic assemblages have a very wide vertical distribution and cannot serve as a reliable basis for establishing boundaries between stratigraphic subdivisions or for correlating sections.

In this connection, in subdividing and tying together sections of coal-bearing deposits, in addition to the biostratigraphic method, we had to resort to other methods of investigation, and in some cases—where organic remains were absent or where the range of their stratigraphic distribution was great—to give preference to these methods. Such methods were cyclic analysis and lithologic-petrographic investigations. The application of these methods yielded the following results:

![Correlation scheme diagram]

Verkhnetersinsky district

Column headings (left section):

• Suite
• Subsuite
• Character of subsuite boundaries
• Second-order cycles and their thickness
• Third-order cycles
• Thickness, in m, of third-order cycles
• Sandstones
• Predominant composition of terrigenous rocks

Stratigraphic labels visible in the section:

• Ilyinskaya
• Kuznetskaya
• Balakhonskaya
• [[unclear: suite name]]
• Usyatsko-Kemerovskaya
• Intermediate
• Ishanskaya
• \(C_{2-3}\)

Visible cycle/thickness labels include:

• 167, X
• 79, IX
• 103, VIII
• 50, VII
• 67, VI
• 120, V
• 50, IV
• 100, III
• 78, II
• 80, I
• 450
• II
• 315
• I
• 5 — 28
• 4 — 20
• 3 — 16
• 2 — 64
• 1 — 75
• 100
• 1 — 50
• 118, V
• 3 — 28
• 2 — 21
• 1 — 66
• 49
• 112, IV
• 3 — 25
• 2 — 25
• 1 — 64
• 69
• 78, III
• 2 — 14
• 1 — 64
• 73
• 106, II
• 2 — 23
• 1 — 83
• 85

Scale: 50, 0, 50, 100, 150, 200 m.

Zalomenskaya depression

Column headings (right section):

• Character of subsuite boundaries
• Second-order cycles and their thickness
• Third-order cycles
• Thickness, in m, of third-order cycles
• Sandstones
• Predominant composition of terrigenous rocks

Visible cycle/thickness labels include:

• 320, II
• 190, I
• 210, VIII
• 88, VII
• 95, VI
• 55, V
• 65, IV
• 80, III
• II
• I
• 100
• 73
• 87
• 97
• 80
• 3 — 32
• 2 — 32
• 1 — 24
• 1 — 71
• 1 — 71
• 1 — 30
• 1 — 57
• 2 — 32
• 1 — 48
• 2 — 92
• 1 — [[unclear]]
• \(C_{2-3}\)
• \(m^2 C_{2-3}\)

Right-margin lithologic labels:

• [[unclear: Osinovskaya?]] rocks
• Tops of lithologic rocks

Fig. 4. Correlation scheme of sections of coal-bearing deposits of the Zalomensky and Verkhnetersinsky districts of Kuzbass.
Compiled by V. I. Budnikov.

1. In studying the coal-bearing deposits of the Zalomensky and Verkhnetersinsky districts, an analogy has been established (of course, in broad outline) in the lithological composition of individual stratigraphic subdivisions; thus, in both districts the number of sandstones in the section of the Ishanovo–intermediate subformation decreases regularly from bottom to top, while in the section of the Kuznetsk formation the coarsest-grained material is concentrated in its middle part.

2. For both districts it has been established quite definitely that, in the composition of the clastic material of the sandstones of the Lower Balakhon formation, grains of quartz and feldspars predominate in the overwhelming majority of cases over rock fragments, whereas in the composition of the clastic material of the sandstones of the Upper Balakhon formation the reverse ratio is observed. Owing to this, even solely by the composition of the clastic material of the sandstones, a quite distinct boundary is indicated in the history of development of these districts, approximately coinciding with the boundary between the Lower Balakhon and Upper Balakhon formations (the districts studied by us are located 130 km apart).

It should be noted that these ratios in the composition of the clastic material of the sandstones vary areally (they are most clearly established in the eastern part of the Zalomensky depression, and least so in the western part of the depression and in the Verkhnetersinsky district). However, the general pattern of change in the composition of the clastic material of the sandstones in the section of the Lower and Upper Balakhon formations is maintained in all the sections of these districts that we studied.

1. In studying the heavy fraction of the sandstones of the Verkhnetersinsky district, the following results were obtained: the sandstones of the Kuznetsk formation are characterized by an increased zircon content (usually more than 13%), as well as by a somewhat increased content and greater diversity in the composition of transparent titanium-bearing minerals in comparison with the sandstones of the Upper Balakhon formation (Fig. 4).

2. Applying the method of cyclic analysis, we distinguish in the sections studied cycles of the first order (macrocycles), cycles of the second order (megacycles), and cycles of the third order.

The cycles of the first order comprise the largest, long-established stages of sediment accumulation and coal formation in the Kuzbass, corresponding in volume to the series of the stratigraphic scheme. In the districts we studied, as a rule, at the base of these cycles (both Balakhon and Kolchugino) there are basal conglomerates and erosional surfaces that can be traced over large areas. In the lower part of cycles of the first order, as was noted by M. F. Neiburg, there occur unproductive, coal-free, “basal” formations (the Ostrog formation in the Balakhon cycle and the Kuznetsk formation in the Kolchugino cycle).

Cycles of the first order are subdivided into cycles of the second order, corresponding in volume to parts of subformations of the stratigraphic scheme. At the base of cycles of the second order, in most cases, there are interbeds of conglomerates, more rarely gravelites, and erosional surfaces are observed; however, their magnitude and extent are considerably inferior to those in cycles of the first order.

Cycles of the second order are subdivided into cycles of the third order—the smallest, in terms of volume, assemblages of lithological rock types, regularly constructed and periodically recurring in the vertical section.

Our correlations of cycles were carried out mainly according to the composition of the rocks composing them, and also according to thickness, which is the first stage in the application of the cyclic method; the next stage is the typification of cycles according to their facies affiliation. But even at the first stage the application of cyclic analysis assists in solving stratigraphic problems; in particular,

we shall show this by the example of correlating sections of the Ishanovo–Intermediate subformation of the Verkhnetersinsky and Zalomensky districts.

In the Ishanovo–Intermediate subformation of the Verkhnetersinsky district, four cycles of sediment accumulation of the second order have been distinguished, the thicknesses of which, respectively (from bottom to top), are 106 m, 78 m, 112 m, and 118 m; at the boundaries of the cycles, erosional breaks are observed in most cases.

The cycles of the second order are subdivided into cycles of the third order, the thickness of which regularly decreases upward along the section of each second-order cycle and recurs at definite intervals of the sections; thus, the third-order cycles lying at the base of second-order cycles have a thickness of 64–83 m, while those lying at the tops have a thickness of 20–28 m (Fig. 4).

Analogous cycles of the second and third orders have also been distinguished in the Ishanovo–Intermediate subformation of the Zalomensky depression, with the only difference that in this district their thickness is in general considerably less than in the Verkhnetersinsky area; however, this decrease in the thicknesses of the cycles is fully consistent with the general pattern of change in the thickness of the Balakhon series within the basin. But in the Zalomensky depression as well we see, in general, the same regular recurrence of third-order cycles of a definite thickness in the section of the Ishanovo–Intermediate subformation, and the same decrease in the thicknesses of these cycles upward along the section of each second-order cycle.

It has been set forth above how we applied cyclic and lithologic–mineralogical analyses in subdividing and correlating sections of the coal-bearing deposits of the Zalomensky and Verkhnetersinsky districts, which are situated along the eastern margin of the Kuznetsk basin. These methods are most effective precisely when we are dealing with sections of coal-bearing deposits situated along the strike of facies zones, i.e., along the shoreline of the basin.

The use of these methods in subdividing and correlating sections situated across the strike of facies zones becomes more difficult, since in this case we encounter rapid variability of stratigraphic complexes both with respect to thicknesses (up to the wedging out of individual horizons) and with respect to their material composition (frequent facies replacement).

In stratigraphic studies these methods must be applied in combination with other methods and, first of all, with the biostratigraphic method—“by means of an organic linking of paleontological data with geological data” [4]. Only in this case can the true boundaries in the history of development of one district or another be revealed, and natural stratigraphic units corresponding to definite geological bodies existing in nature be distinguished.

CITED LITERATURE

1. Zhemchuzhnikov Yu. A. Subdivision of the Kuznetsk section of the barren (Kuznetsk) suite. Vestnik ZSGU, issue 3. 1944.

2. Muromtsev V. S. On the age of the Ostrog suite of Kuzbass. Doklady AN SSSR, vol. 95, No. 5. 1954.

3. Khalfin L. L. Lamellibranch mollusks of the coal-bearing deposits of Kuzbass. Transactions of the Mining-Geological Institute of the West Siberian Branch of the Academy of Sciences of the USSR, issue 9. 1950.

4. Khalfin L. L. Introduction to the biostratigraphy of the coal-bearing deposits of the Kuznetsk basin. “Problems of the Geology of Kuzbass,” vol. 1, Ugletekhizdat. Moscow. 1950.

Siberian Branch of VNIGRI.