NEW DATA ON THE KARST OF NORTHEASTERN SALAIR

P. M. Bolshakov

GEOLOGICAL STRUCTURE

The study of the karst of Salair was episodic in character and was a component part of a complex of geological-prospecting investigations. The largest works in the field of karst study were carried out by the Ur Party of the West Siberian Geological Trust, which in 1936 conducted a hydrogeological survey in northeastern Salair under the direction of the author (3 and 4). The survey was carried out at a scale of 1 : 100000 and covered an area of 1400 km², the boundaries of which may be judged from the attached geological map (Fig. 1).

New data on karst were obtained during the period of engineering-geological investigations of 1939, carried out by Sibtransproekt of the NKPS in the area of the projected route of the Altaiskaya—Kuzbass railway. The work of 1939 made it possible to fill gaps in the 1936 survey and to collect material on karst manifestations in Devonian limestones developed near the Artyshta siding of the Novosibirsk—Stalinsk railway line.

In orographic terms, the investigated area is an example of an erosional landscape characterized by softly outlined contours and a dense network of river valleys, ravines, and gullies. The most elevated relief marks are: Mt. Kopna, with an absolute elevation of 504.0 m; the hill near the village of Cherenkovsky—488.6 m; and the hill in the upper reaches of the Yurman River—436.7 m. The lowest areas are expressed by the thalwegs of the valleys of the Kosma, Ur, and Ch. Bachat rivers, with surface elevations of 181–210 m. The excess of the highest points over the lowest reaches 300–323 m. Among the principal elements of the relief of the region, three forms must be distinguished. 1) Planation surfaces, dominant on the Salair Ridge proper in the form of alternating steps. In places they are complicated by monadnock hills and by the hydrographic network. 2) The steep northeastern scarp of Salair, facing toward Kuzbass and sharply expressed in the relief. The scarp is especially conspicuous in the Tyrgan area and along the Guryevsk—Pesterevo stretch, where it reaches 150–200 m of relative height. 3) A valley–gully–ridge landscape characteristic of the margins of Kuzbass adjoining Salair.

The hydrographic network of the region is expressed by rivers of orders II, III, IV, and V of the Ob basin, insignificant in water discharge. Among them we note the Kosma, Biryulya, Ur, Ch. Bachat, and S. Bachat rivers with their tributaries. On the slopes of the valleys of the main river arteries, two clearly expressed terraces are encountered: a floodplain accumulative terrace 2–4 m high and an above-floodplain accumulative terrace 8–11 m high.

The scheme of the geological structure of the region is as follows. Along the long side of the area and in its middle, the most ancient rocks—the Gavrilov limestones of the Lower Cambrian—extend in a broad belt to the northwest.

Along the long axial part the Gavrilovo limestones are cut by an effusive complex of rocks of the Pecherkino Formation of the Middle Cambrian (Fig. 1). The stratigraphically overlying effusive-sedimentary Middle Cambrian deposits (the Ancheshevo, Novoprosvetovo, and other formations), which are not widely developed, are also concentrated in the belt of distribution of the Gavrilovo limestones and the Pecherkino Formation. Diabase dikes are encountered rather often in all these formations. The Cambrian rocks constitute the ancient core of the geological structure of the region; Silurian and Devonian deposits, in which rocks of the sedimentary type predominate, are attached to its margins. On the basis of stratigraphic and lithological features, the carbonate rocks affected by karst may be combined into three principal groups.

Cambrian group. Over a large area of the district the Gavrilovo limestones of the Lower Cambrian are developed; they extend in a continuous belt from the village of Gavrilovskoye northwestward to the Kosma River. They are crystalline, white or light gray, pure, in places pinkish from an admixture of secondary hematite, and more or less marbleized. The formation of the limestones proceeded under various facies conditions, as is eloquently indicated by the presence in them of small lenses of marls and interbeds of sandy-clayey and tuffaceous material. The total thickness of the limestones reaches 2.5–3 km. The Khomutino horizon of limestones of A. G. Vologdin (6) and the “roofing” limestones of B. F. Speransky (18), which are of Upper Cambrian age, are also assigned to the Cambrian group. The roofing limestones have been recorded in the area of the town of Guryevsk, and the Khomutino horizon—along the banks of the Khomutina River, where it has a limited distribution. It consists of crystalline white, pinkish-white, and brownish-red-toned limestones enriched in clastic material, the latter occurring here in greater quantity than in the Gavrilovo limestones. Near the village of Gorskina the thickness of the Khomutino limestones is 200–250 m.

Silurian group. In this group we include only the Upper Silurian limestones and do not include the Lower Silurian limestones, which we did not examine. Here we have in mind the ostracod horizon of limestones, distributed near the village of Pesterevo and the village of Arinicheva (11 and 27). It is represented by dark and dark-gray massive and bedded bituminous limestones, having a thickness near the village of Arinicheva of 190–200 m.

Devonian group. The Zhelin Stage (\(D_1^1\)) has been identified at the Krekovo mine in the Guryevsk area, where it is represented by the Krekovo gray, light-gray, and yellowish-brown limestones. They are usually massive, dense, and fairly pure; their thickness is 400–500 m (11). The Koblenz Stage (\(D_1^2\)) is expressed by light-gray and gray, massive or indistinctly bedded Pesterevo limestones, developed in the middle part of the village of Pesterevo. Their thickness is 300–400 m. In the Middle Devonian, limestones occur both as lenses in sandy-clayey rocks and as separate thick strata. Among the latter we note the Akutolobatovo (Salairka) limestones, recorded along the banks of the Salairka River and the Ura River in the vicinity of the village of Pesterevo. They are light gray, gray, rarely dark gray, dense or bedded. Their thickness is small (tens of meters). Above the Salairka limestones lie dark-gray, gray, sandy-clayey, bituminous, bedded conchidium (Karachkino) limestones, which occur on the right bank of the Chernevoy Bachat River in the vicinity of the Guryevsk plant, where their thickness reaches 800–900 m.

On the surface of the bedrock of the region lie loose products of an ancient lateritic weathering crust and Quaternary deposits. The products of the ancient weathering crust are for the most part represented by var-

with colored impermeable clays and, more rarely, with coarse clastic material (stony bauxite, crushed stone, pebbles, sand, etc.). They occur predominantly in secondary bedding and are confined to negative relief forms expressed by ancient buried valleys, basins, and karst funnels. Within the area under consideration, the thickness of the products of the weathering crust is measured at no less than 35 m, as has been proved by exploratory work on the territory of the Shirokii Log clay deposit (7). The Quaternary rocks include cover loess-like loams, alluvial and deluvial formations of varied lithological composition, which lie directly upon the bedrock or upon the products of the ancient weathering crust. The distribution and thickness of the loose Quaternary rocks are far from uniform. Within watershed spaces, cover yellow and dark-yellow loess-like loams are usually developed, with insignificant thickness (up to 10–15 m). In the lowered parts of river valleys, in addition to cover loams, alluvial loams, clays, sands, crushed stone, and pebble beds are widespread. Here the total thickness of the loose stratum is determined at up to 40 meters or more. Along gentle slopes of valleys and watersheds, rocks of varying thickness occur, consisting of coarse clastic material, deluvial and loess-like loams. In the upper part of steep slopes and on the tops of hills, loose rocks are absent. With the exception of coarse clastic material, the loose formations are comparatively poorly permeable.

The bedrock of the range, having a steep southwestward and northeastward dip, generally extends from southeast to northwest. But against the background of the predominant northwestward strike of the rocks, gathered into plicative forms, it is possible to note thrust-overthrust forms of disjunctive disturbances, which complicates the tectonics of the area. A large number of disjunctive disturbances pass along the northeastern boundary of the range, where, as a result, ancient Cambrian formations are thrust over the younger Paleozoic rocks of Kuzbass. More often, major longitudinal disjunctive disturbances occur, oriented to the NW, i.e., parallel to the strike of the plicative forms; less often there are tectonic fissures of the transverse type, extending in a SW direction.

The modern relief of Salair arose as a result of the complex influence of tectogenesis and denudation processes, which began in the Paleozoic and continue at the present time. Without going into the details of the complex phases and epochs of tectogenesis (24) that formed the geological structure of Salair, we shall consider the karst forms, which are confined exclusively to areas where limestones are distributed.

Morphology of Karst Formations

The presence of a cover of loose deposits on the surface of the limestones masks the karst forms. They appear most clearly on flat elevations and on gentle valley slopes. In the relief, karst forms are typically expressed on the territory of the Nekrasovskoe (Gavrilovskoe) and Arinicheskoe deposits of refractory clays, in the area of Shirokii Log, and of other deposits of bauxites and brown iron ores. The morphological forms of karst in the area include: 1) funnels, 2) basins, 3) caves, and 4) dry (dead) valleys.

Funnels

The principal form of karst manifestation in the relief is funnels. The greatest number of funnels has been found on the surface of Cambrian י

limestones. For the clay deposits of Shirokii Log, situated within the Gavrilovo limestones, A. G. Vologdin (6) recorded 100 sinkholes over approximately 1 km² of area. Sinkholes are also encountered in large numbers at the Nekrasovo, Arinichevo, Vaganovo, Krasnino, and other deposits of clays and brown iron ores. In smaller numbers they occur in the Bugachëvo, Karachkino, and Baskuskan areas, which lie in the karst zone of Devonian limestones. In areas where Silurian limestones are distributed, sinkholes are extremely rare. In plan, the sinkholes have varied forms: circular, elliptical, ovoid, and irregular. Circular, elliptical, and ovoid sinkholes are confined to flat watersheds, while pear-shaped ones occur on steep slopes, with the widened part of the sinkhole situated on the higher side of the slope. They are arranged in groups or chains, extending along the strike of the limestones and along longitudinal tectonic fissures, which is a characteristic feature of the region. The sinkholes of the headwaters of the Baskuskan River are somewhat distinct in their arrangement. Lying on the floor of a dry valley, they extend along a broken line that first runs northwest, then turns sharply northeast, and finally turns again northwest (Fig. 2). This arrangement of the sinkholes should probably be explained by their confinement to longitudinal and transverse tectonic fissures cutting the Devonian limestones. The presence of tectonic faults in this area was repeatedly recorded by researchers in previous years. K. V. Radugin (15) traced two transverse disjunctive disturbances extending parallel to the Amnikha River. Smaller-scale tectonic faults have been exposed by a quarry at the second Baskuskan deposit of Devonian limestones. As V. I. Yatsuk and M. A. Zablotskaya (28) note, the quarry contains fault-type fissures that can be traced down to the very floor of the quarry without changing their width. Near the land surface the fissures widen somewhat, forming, in cross-section, a semblance of sinkholes. These examples prove that the karst sinkholes in the Baskuskan area are territorially and genetically connected with tectonic fissures cutting the Devonian limestones.

In addition, one may note the large number of sinkholes at the contact of limestones with sandy-clayey rocks. In this respect, the most striking example is the chain of sinkholes within the Gavrilovo limestones at their contact with readily kaolinizing shales, identified on the territory of the Shirokii Log clay and bauxite deposit.

The sizes of the sinkholes in the region vary within considerable limits, reaching as much as 200 m or more along the long axis. In depth, the sinkholes have semi-ovoid, conical, and irregular forms. The steepness of the slopes of conical and semi-ovoid sinkholes ranges from 10 to 45 degrees or more. Counting from the surface of the limestones, the depth of these sinkholes reaches up to 30 m. In the relief they have a lesser depth (up to 10–15 m), since they are filled from above with loose deposits. Sinkholes of irregular form (collapse sinkholes) have sheer walls composed of limestones (a log in the headwaters of the Baskuskan River). On their floors there are fragments and rubble of limestone with an admixture of loose material. Very rarely, the mouths of fissures and channels descending into the depths approach the floors of such sinkholes, owing to which the sinkholes are water-absorbing (ponors). To a lesser extent, sinkholes filled with stony bauxites, sands, and pebbles with an admixture of clay should be considered water-absorbing. Sinkholes filled with impermeable fat clays and kaolins are entirely non-absorbing. On the floors of such sinkholes, encountered in the area of the Nekrasovo and Arinichevo deposits of refractory clays, rainwater and spring meltwater accumulate.

... waters, forming temporary lakes. Some large sinkholes partially drain the groundwater of the loess-like rocks (perched water), as a result of which bogginess appears on their bottoms and water-loving vegetation takes root.

In the formation of the sinkholes the principal role was played by corrosion and suffosion processes. In individual cases these processes were supplemented by collapse phenomena, which produced sinkholes with sheer walls.

Basins.

Basins differ from sinkholes in their large size and the presence of water. The basins may include saucer-shaped and funnel-shaped depressions situated within the Nekrasovo deposit of refractory clays. Their dimensions along the long axis reach 200–300 and more meters. Some basins, seized by erosion, have lost their characteristic features of a closed form and have turned into cirque-like depressions open on one side. In this respect, of interest is a cirque-like depression located at the headwaters of the Golodaika River and giving outlet to a spring of considerable discharge of fissure-karst waters (spring No. 84).

Caves.

This form of karst has been insufficiently identified. In the Gavrilovo limestones the Gorskino and Gavrilovo caves have been recorded; the latter is described below. The mouth of the Gavrilovo Cave is located in the lower half of the left bedrock slope of the valley of the B. Tolmova River, 20 m along an azimuth NW : 290° from the dead end of the Salair branch of the railway and at a height of 25–30 m above the water level in the river. The entrance to the cave is expressed as a channel in the form of a truncated cone with uneven walls, to some extent worked by the hand of man. Counting from point 1 to point 2 (Fig. 3), the channel descends at an angle of 33° toward NW : 305°. Its initial diameter is 1.5, the final one 1.0, and its length is 9.0 m. In the lower narrow part of the conical channel the bedding elements of the Gavrilovo crystalline limestones of the Lower Cambrian, to which the cave is confined, were measured. The direction of dip of the limestones is oriented to NE : 20° ∠ 46°. The limestones are cut by cracks along the bedding and perpendicular to it. From point 2 to point 3 a cavity (channel) was traced, having in cross section the form of an irregular quadrilateral and a length of 8.10 m. The cavity descends toward point 3 at an angle of 33°, along an azimuth SE : 120°. At point 2 it has a width of 2.0 and a height of 2.0 m, the latter decreasing at point 3 to 1.0 m. Approximately from the middle part of the channel a branch goes off to the right, merging with the main channel at point 3. This branch is characterized by an almost circular section with a diameter of 0.80–1.0 m. Both its walls and the corners at the turns are rounded by the work of flowing water. In the channel between points 2–3 the walls and ceiling are more often angular. On its floor are accumulated large blocks and rubble of limestone, collapsed from the ceiling and walls. The cross section of the channel changes sharply along its length. It narrows to a tight passage, then swells into broad chambers. Between points 3–4 there is a channel of triangular section, whose length is 5.5, height 1.0, and width at the base 2.0 m. The channel descends to NE : 85° with an angle of 44°. On its floor, besides blocks and rubble of limestone, lie brushwood and wooden billets that have fallen in from the surface. In the interval of points 4–5 there is a small cavity, dipping at an angle of 38° toward NE : 60°. The bottom of the cavity is uneven, with depressions in the bedrock. In narrow sections...

the walls of the cavity are well polished by flowing water; conversely, in the widened sections they are enriched with karren gutter-like deepenings and niches, as well as fissures that end bluntly. The vertical section of the cavity approaches a semicircle, the arch of which faces upward. In places, stalactitic formations of various shapes appear on the walls and ceiling. On the walls the stalactites resemble the fleece of a curly ram; on the ceiling they are represented in the form of icicles and grape-like clusters consisting of calcite, somewhat contaminated by clayey admixtures. From point 5 to 7 there extends one almost horizontal channel with a total length of 13 m, oriented NE : 50—55°. Having the appearance of a narrow corridor, at point 7 it widens considerably, taking on the form of a hall with a dome-shaped ceiling, on which pits and depressions are found. The height of the hall is 1.8—2.0 m and its width 3.5—4.0 m. From the center of the hall to point 8 a horizontal tunnel, 10 m long, has been traced. On the floor of the hall and tunnel are accumulated blocks of limestone and red-colored cave clay, as well as clayey products of an ancient weathering crust, carried into the cave by flowing waters. From point 8, at SW : 170°, the indicated tunnel continues in the form of a fissure which, rising slightly upward, ends in a blind pocket filled with wet red-colored clay. The karst forms characterized along the line 2—8 constitute the eastern half of the main passage of Gavrilovskaya Cave. Counting from the mouth of the cave, the main passage has a western half, shown in Fig. 3 by the line 2—9—10—12 and forming a single whole with the eastern half of the main passage. Without considering the cavities between points 2—9—10, which are basically analogous to those of the eastern half of the passage, let us dwell on the description of the large chamber outlined by points 10—11—12—12¹. It has the appearance of a hall, the ceiling of which is a more or less even surface inclined in the direction of the dip of the rock layering. On the ceiling there appear gutter-like and tubular karst cavities running both conformably with the bedding of the limestones and perpendicular to it. On the floor of the hall, which is also inclined along the dip of the beds, there is observed a chaos formed by piled-up blocks and fragments of limestone, the sizes of which reach up to 3.0 m in long cross-section. The accumulation of this chaos of blocks occurred as a result of the collapse of the ceiling along the plane of bedding, fracturing, and developed karst cavities in the limestones. In the survey conducted it was possible to penetrate to a depth of 15 m from the mouth of the cave and along the periphery for 90 m, with no flowing water encountered in it. Only on the walls and on the ceiling of the cavities are drops of water observed. It was not possible to descend below the indicated depth, because of the small dimensions of the cavities plunging downward. The total volume of the cave cavities exceeds 500 m³. The air temperature in it, determined on 10/VII—39, was 5°C.

An analysis of the factual material on Gavrilovskaya Cave makes it possible to draw the following conclusion. The formation of the cavities was due chiefly to erosional and corrosional processes that acted intensively in the distant past. The corrosional activity of the waters is indicated by: 1) karren grooves on the walls of the cavities, 2) the formation on the ceiling and walls of the cave of small pits and depressions, and 3) accumulations in the cavities of red-colored cave clay as a residue from the dissolution of limestones. The mechanical activity of flowing water, in turn, is indicated by: 1) the presence of domes, probably formed by the mechanical action of water under high pressure, 2) the rounding of corners where cave channels branch and merge, and 3) smooth polished wall surfaces. True, we have also pointed out angular walls of cavities. But this does not contradict the proposition of the corrosional and erosional formation of the cave. The angular contours resulted in re-

as a result of the collapse of rocks from the walls and ceiling of cavities, where the breaking away of rock could occur along cracks only weakly developed by karst waters. At the same time, we believe that in some cavities the collapse of limestones took place after flows of karst waters had existed in them; for this reason the necessary conditions were also lacking for the treatment of angular outlines by corrosion and erosion processes. At present, the enlargement of the cave cavities proceeds at a slowed rate, which is explained by the weak circulation of water in it. The weak circulation of water in the cavities is due to two main causes. First, the principal underground channels that bring water to the cave are plugged with impermeable clay or have been completely cut off by denudation. Second, the routes by which surface waters enter the cave from the upper part of the slope of the Tolmova River valley are, for the most part, cut off by a deep railroad cutting in the limestones, which runs along the elevated part of the slope at a distance of 40–50 m from the mouth of the cave. Consequently, the Gavrilovka cave lies in a zone of dry karst that drains surface waters only from a small catchment area.

In addition to the caves noted, cave-like hollows occur in the Gavrilovka limestones in rocky limestone scarps. They are usually small in size, occurring on the right slope of the valley of the Ponkrashka River near the village of the same name and on the left slope of the valley of the Ch. Bachat River, 5.5 km above the town of Guryevsk. No caves have been found in the Silurian limestones. They have been recorded in small numbers in Devonian rocks during the opening of the Guryevsk and Baskuskan quarries. Small channels of circular or elliptical section were exposed in them; their dimensions in cross section do not exceed 1.0 m. The channels are open or filled with varicolored clay containing limestone gravel and fragments.

Dry (dead) valleys.

Karst in the limestones imparts its own specific features to the hydrographic network of the district. Following the classification of A. A. Kruber (9), all karst rivers can be assigned to three types. The first type comprises perennial permanent rivers that rise in areas of distribution of impermeable rocks and cut through the entire karst mass. Owing to the abundance of water and considerable erosive force, they are able to deepen their valleys to the groundwater level or to the underlying impermeable rocks and therefore to retain their viability. This type includes the major water arteries of the district—the Kos’ma, Biryulya (Ur), and Ch. Bachat rivers—which are characterized by a minimum water discharge of 2–3 m³/sec. Within the Salair Ridge their valleys, laid across the strike of the geological structure, are deep and well developed. Sheer cliffs are exposed on the valley slopes. The second type comprises rivers that rise within karst areas and receive recharge from springs with a large discharge. This category includes the small rivers and streams of northeastern Salair—the Baskuskan, the headwaters of the Golodayka, the Guryevsky stream, and others. Their sources are formed by powerful springs of fissure-karst waters and are located in cirque-shaped depressions. On leaving the limestones, they carry their waters to rivers with larger discharge. The third type comprises numerous karst rivers that flow over the surface only for a limited distance and are then swallowed by ponors. More often these rivers rise in an area of impermeable rocks, but, upon entering the karst, they lose their water in cracks and ponors. The following rivers of the area studied belong to the third type: Kopanets, Sukhaya Rechka, and the Cherenkovsky Kl. Special attention is deserved by the Ko-

panets, which begins on the slope of Mt. Kopna. Its headwaters, confined to the area of development of Silurian sandstones and shales, have a surface stream. When the latter enters the territory of karstified Cambrian limestones, its water begins to be lost, remaining as small pools of standing water. Four km above the village of Podkopennaya the water in the channel disappears completely, and right up to the mouth of the little river the valley is dead (dry).

The headwaters of Klyuch Cherenkovsky, which begins 1 km to the southwest of the settlement of Cherenkovsky, lie within the Pecherkino Formation. Two hundred m below the swampy headwaters, the discharge of water in the spring reaches 2 l/sec. Still lower, the valley acquires a gorge-like transverse profile, cutting across the strike of the metamorphic shales. Seven hundred m below the headwaters, the valley, entering limestones, widens sharply, and the water of the spring is repeatedly either lost in the bottom or reappears. In the area there are also small dead valleys, which should be called dry valleys (the rivers Opletikha, Sukhaya Kamenka, and Kinteperikha), where water appears only during seasonal floods.

The enumerated surface forms of karst are closely connected with underground (deep) karst, as shown by observations in Gavrilovskaya Cave, the Guryevsk and Baskuskan quarries, the excavation at 8.5 km of the railway branch to the Guryevsk-Salair Mine, and Shaft 2-bis of the Ursk placer deposit of Zapsibzoloto. The Guryevsk quarry, where the Kuznetsk Metallurgical Combine exploits Devonian limestones, is described in detail in the works of A. M. Kuzmin (10) and E. V. Butkevich (5). In the middle part of the quarry, near the lime kilns, tubular and slit-like karst forms at depth sometimes take on more complex forms of caves, niches, channels, sleeves, and fissures, which now widen, now narrow, now go in one direction, now turn sharply in another, mainly obeying the dominant fracturing of the limestones. In the excavation at 8.5 km of the railway branch to the Guryevsk-Salair Mine and in the Baskuskan quarry, deep karst is encountered in the form of caves, channels, and fissures plunging downward. They are filled with red-earth weathering products or are devoid of the latter.

As for the depth of penetration of underground forms of karst, there are no concrete data on this question. The large amount of geological-exploration work carried out at the Salair and Ursk mines did not provide the necessary material on underground karst. Therefore one has to use indirect data. It is known to us that the depth of the leaching and oxidation zone of the polymetallic ores of the Saimonovskoye deposit reaches 150 m from the ground surface (12) and 80–90 m below the level of surface streams. It follows from this that deep karst, which likewise depends, like the oxidation zone, on the circulation of groundwater, may in some places be developed 80–90 m deeper than the water level in the rivers of the region. To regard the depth of distribution of karst at 80–90 below the water level in the rivers as exaggerated is impossible, since within the Devonian limestones of the Karachkinskoye deposit, as geophysical investigations have shown, the level of karst waters lies deeper than 180 m absolute elevation, i.e., 27.6 m below the water’s edge in the Ch. Bachat River. In considering the lower boundary of deep karst, one must not forget the following very important circumstance. Salair is characterized by the presence of ancient valleys, which have repeatedly been recorded at various hypsometric elevations (7, 17, and 26). K. V. Radugin (15) found ancient valleys on the watersheds of the Tom—Chumysh and Kara-Chumysh rivers, Grinko—in the area of Zolotaya Mountain, and geologists of Sibtransproekt in the headwaters of the Baskuskan River (199 km of the Altaiskaya—Kuzbass route). According to the views of B. F. Speransky (18), in Salair three types of ancient valleys may be distinguished, differing in degree of development and age, and their plan configuration in places does not correspond to the configuration of the present-

...of present-day valleys. In the latter case they are weakly expressed in the relief, since they are buried by loose formations. One type of ancient valleys (the second type of Speransky) is distinguished by the greatest degree of development. The watercourses of this type of valleys lay tens of meters deeper than the channels of modern rivers and represented the lowest erosion base of the region, determining within the limestones the lowest base level of karst formation. In this connection it is quite admissible that the lower boundary of karst formation lies 80–90 m deeper than the water line of modern rivers, as was indicated earlier.

The foregoing considerations apply to deep karst, whose development depends on the position of local bases of erosion, both ancient and modern. Deep karst probably reaches still lower levels in zones of tectonic disturbances, along which underground waters may circulate at depths of more than 1 km below the erosion base, emerging at the daytime surface in areas very far removed from their recharge area.

The totality of the karst forms characterized above defines the karst landscape of the Salair region. It differs somewhat from the landscape of the classical karst regions situated in the western part of the Balkan Peninsula, in Italy, and in Mountain Crimea. In the regions mentioned, the limestones are not overlain by loose deposits, in consequence of which corrosion and erosion processes are manifested intensively on the limestone surface, forming typical karren fields. In this case the karst landscape is most clearly expressed in the relief. In the terminology of F. Katzer (8), it is called uncovered (bare) karst (nackter oder offener Karst), or, in the terminology of L. Sawicki (16), Mediterranean-type karst. On Salair, karren fields are not widespread, which is explained by the presence of a thick cover of loose deposits on the limestone surface. By analogy with the Kizel karst (19), the Salair karst should be assigned to the covered, or Central European, type of karst regions. The karst of the region is covered both by loose deposits and by bedrock non-carbonate rocks.

The Principal Factors Influencing Karst Formation

The forms of karst manifestations and the degree of intensity of karst formation are conditioned by a complex set of factors (1, 20, 21, and 25). With regard to the Salair region, we shall consider the principal factors: 1) the chemical and mineralogical composition of the rock and its structure; 2) bedding, joints of separation, and tectonic fractures; 3) homogeneity of the limestones (interbedding with aquiclude layers and contact effects); 4) the climatic factor; 5) the area of distribution of the limestones; 6) the hypsometric position of the limestones; 7) the thickness of the loose cover; and 8) hydrogeological factors.

To clarify the role of the chemical and mineralogical composition of limestones in karst formation, laboratory investigations were carried out. Chemical analysis of the rocks was performed by the laboratory of the Tomsk Industrial Institute under the direction of senior lecturer I. P. Onufrienok, and their mineralogical composition was studied by the geologist of the ZSGT M. P. Nagorsky. In addition, we used the results of chemical analysis of limestones from the works of Prof. A. M. Kuzmin (10)¹ and Assoc. Prof. V. A. Nudner (13). The general results of the chemical analysis are pre—

¹ The data of A. M. Kuzmin are indicated in the text by an asterisk (*).

entered in Table 1. Let us note the most characteristic indicators of the limestones: CaO from 49.79 to 55.96; MgO from 0.03 to 1.83*; SiO₂ from 0.09 to 7.97%, and insoluble residue from 0.14 to 2.37%. By the composition of the insoluble residue, the limestones are divided into three main groups: a) limestones with an insoluble residue in which secondary quartz predominates, comprising up to 95% of the entire composition (samples Nos. 1, 5, 6, 7, 8, 10, and 11); b) limestones with an insoluble residue consisting of minerals of the kaolinite group (samples Nos. 2, 12, 13, and 14); and c) limestones with an insoluble residue of clay minerals (samples Nos. 3, 4, and 9). Limestones with an increased content of insoluble residue (samples Nos. 2, 7, 8, and 11) are only weakly subject to karst formation. This group includes silicified Cambrian limestones (outcrop No. 11, 184, etc.—see Fig. 1), silicified and bituminous Arinichev limestones of the Lower Silurian, and Pesterev limestones of the Lower Devonian (outcrop No. 276). Conversely, weakly silicified Cambrian limestones are readily subject to karst formation (Gavrilovskaya Cave, the face of shaft 2-bis of the Ursk goldfield, the headwaters of the Zolotoi key—outcrop No. 245, outcrop No. 34, etc.).

A small number of samples were subjected to microscopic study. Therefore, no definite conclusions can be drawn about the significance of the structure and texture of limestones for karst processes. But, apparently, structure plays no smaller a role in these processes than the chemical composition of the rocks. On the basis of limited data, it may be said that coarse-grained and partly clotted structures are more susceptible to dissolution in water than silty structures enriched with dust-like particles of bituminous matter. It must be assumed that, for these reasons, the Arinichev and Pesterev limestones with a silty structure did not display any noticeable karst-forming capacity.

O. L. Enor (25, p. 159) does not attach great importance to the dissolution of limestones along bedding and schistosity. One cannot agree with this opinion, since karst formation along bedding cannot extend to great depth, affecting only the zone of physical weathering. Undoubtedly, tectonic fractures plunging to considerable depth are a more favorable factor for karst formation than bedding fractures. Many authors (9, 20, and 25) associate the particular development of karst with zones of tectonic fracturing. This proposition is fully confirmed by the factual material on the karst of Salair. As already stated above, karst cavities in the limestones in the Gur’evsk and Baskuskan quarries are associated with zones of tectonic fractures. The strike of chains and groups of sinkholes parallel to the tectonic faults of the area likewise indicates that the karst is confined to zones of tectonic fracturing. In this respect, a particularly typical example is provided by the sinkholes in the headwaters of the Baskuskan River, situated along intersecting longitudinal and transverse tectonic fractures (Fig. 2). While giving due weight to the significance of tectonic fracturing in karst formation, we must emphasize that the extent of the majority of karst sinkholes is also parallel to the jointing fractures of the limestones. It is possible that here all three factors are favorably combined for karst formation, i.e., bedding, jointing fractures, and tectonic faults. Therefore, when comparing the data of the three factors in karst formation, it is advisable to pay attention to the internal surface of the rocks, representing the totality of the surfaces of fractures and pores. This factor plays an exceptionally important role in selective weathering: the greater the internal surface, the more strongly the rock weathers (23).

The homogeneity of limestones generally increases the degree of karst formation, as may be judged from the homogeneous Gavrilov limestones

Table 1.

Results of chemical analysis of limestones

of the Nekrasovsk deposit of refractory clays, strongly affected by karst.

At the contact with shales containing pyrite, limestones undergo intensified karstification, as has been demonstrated by the example of the limestones of Shirokii Log (Fig. 4). Phenomena of this kind have repeatedly been noted by investigators of the karst of the Mountain Crimea (9) and of the karst of the Kizel district in the Urals (19 and 25). In this case, chemical, geological, and hydrogeological factors exert a special influence on the intensive development of karst. Iron plays an important role in the complex course of the chemical reaction. The iron pyrites contained in the shales, under the influence of water and atmospheric oxygen, are oxidized into ferric sulfate and sulfuric acid. Ferric sulfate, being a strong oxidizing agent, burns the carbonaceous compounds of the shales with the release of carbon dioxide gas (CO₂), which, upon entering the water, accounts for the latter’s highly aggressive properties. The content of carbonic acid in the water greatly increases the solvent capacity of the water, especially with respect to the calcium and magnesium carbonates that are practically insoluble in pure water. Carbonic acid converts them into soluble bicarbonates according to the formulas:

$$ \mathrm{CaCO_3 + CO_2 + H_2O = Ca(HCO_3)_2} $$

$$ \mathrm{MgCO_3 + CO_2 + H_2O = Mg(HCO_3)_2.} $$

Under appropriate geological conditions, the chemical action considered may be supplemented by a hydrogeological factor. If limestones are underlain by shales, then at their contact conditions are created for the formation of well-defined aquifer horizons or underground watercourses that promote intensive karstification. A striking proof of this proposition may be the presence of the Guryev spring of fissure-karst waters, confined to the Gavrilov limestones of the Lower Cambrian, which are in tectonic contact with the green-lilac formation of the Middle Cambrian and the conglomerates of the lower part of the West Altai Lower Ordovician formation (Fig. 5). The Guryev spring has a discharge of up to 36–40 l/sec and is one of the large springs of northeastern Salair, about which we shall speak in more detail below.

The processes of rock destruction at the contact of limestones with shales can be illustrated by numerous facts, especially for the area of distribution of the Gavrilov limestones interbedded with shales, effusive-sedimentary, and effusive formations. Incidentally, we emphasize that weathering of limestones at the contact with noncarbonate rocks can proceed intensively only in the early (young) stage of karst. Later, as the limestones are destroyed and karst funnels form in them, a stage of retardation of karstification sets in. This occurs because surface waters flowing into the funnels bring fine clayey material and deposit it on the bottom of the funnel. The clayey material, together with coarse fragments (deluvium and talus), covers the limestones and cuts off access to them by surface waters, thereby slowing further karstification.

The question of the influence of the climatic factor on the intensity of karst processes must be posed in two directions, considering the modern and the ancient climate. The features of the modern climate of Salair, under which favorable conditions for the formation of underground waters are created in depressions of the relief, probably differentiate the limestones of such areas and intensify karstification. We attach greater importance in the karstification of limestones to the climate of more remote epochs. Obviously, in the Jurassic or Tertiary period, when on Salair there existed—

...had a hot and periodically humid climate, karst processes were exceptionally intensive. In this period, under lateritic weathering, surface and underground waters were enriched with a large quantity of humic acids, carbonic acid, and sulfuric acid, which could increase the solvent capacity of the waters many times over. In connection with this, we believe that the dominant part of the karst forms described above was established in the epoch of lateritic weathering. The later erosion of the weathering crust filled most of the karst forms with products of this crust, which now occur in abundance in the form of variegated refractory clays, sands, bauxites, and brown ironstones. The filling of ancient karst sinkholes, caves, and fissures with products of the weathering crust—most often expressed as impermeable clays more than 10 m thick—contributed to a slowing of subsequent karst processes in the limestones of the region. As follows from the data of geological-prospecting work for placer gold, bauxites, and refractory clays, many ancient karst sinkholes are completely filled with products of the ancient weathering crust and are not expressed on the present-day surface. Younger karst forms, filled also with Quaternary deposits, are due to later karst formation, which continues even now, but at a slower rate than in the distant past. The activity of karst at the present stage is indicated by frequent outlets of karst-water springs and by collapses in sinkholes, where the loose rocks have a compacted appearance with slickenside planes. Such a condition of the loose rocks was noted by Academician M. A. Usov (22, p. 7) in shaft No. 1, sunk in Shirokii Log. No less characteristic evidence of active karst is provided by open karst sinkholes in the upper reaches of the Bascuskan River, confined to Devonian limestones. The development of karst processes at the present time is caused by tectonic uplift of the Salair Ridge, as is demonstrated by the formation of the steep scarp of Salair, facing toward Kuzbass, and by the rejuvenation of bottom erosion in the rivers of the region (Alambai, Kosma, Biryulya, and Ch. Bachat) flowing within the ridge.

We have cited examples of intensive karst development in areas of extensive limestone distribution (the Nekrasovskoe and Arinichevskoe deposits of refractory clays, etc.). Thin limestone interbeds overlain by watertight interbeds are protected by the latter from access by surface waters. For the Salair region we cannot cite demonstrative examples of a negative influence of watertight interbeds on the karst process. Another factor—the contact effect (metamorphism) of neighboring igneous rocks—has a pronounced effect. Limestones affected by secondary silicification (outcrop No. 11), like other silicified rocks of the ridge, react only weakly to weathering.

The hypsometric position of the limestones determines not only the intensity of karst formation but, according to the opinion of many authors (1 and 25), can predetermine its direction and the emergence of a certain aspect of karst forms. The intensity of karst formation is distributed according to the law of the erosional activity of open streams, weakening below the level of groundwater. In elevated areas it is stronger, in lowered areas weaker; moreover, it is most intensive in the zone of vertical water circulation. This could not fail to affect karst formation in the limestones of the region. Evidently, in connection with this, the Cambrian limestones, developed as a broad belt within the planation surfaces of Salair and situated high above the local erosion bases, underwent strong karstification. Conversely, the Devonian limestones, confined to the foot of the Salair scarp and to areas of the ridge-and-valley landscape of Kuzbass, are karstified considerably more weakly than the Cambrian rocks.

A thick loose cover on limestones hinders the development of karst, which is a generally known fact. It protects the limestones from access by surface waters. Additional factors (rock structure, angle of dip, etc.) affecting the intensity of karst processes are not considered by us, for lack of the necessary observations. We shall only note that the predominantly steep dip of the limestones of the region must have a negative effect on karst formation.

In terms of the intensity of karst formation, the limestones of northeastern Salair are divided into two main groups. The first group includes the Cambrian (Gavrilovka and Khomutino) limestones, and the second encompasses the Silurian and Devonian limestones. In the pure Cambrian limestones, distributed over a vast area of the Salair Upland, the factors favoring karst formation have combined most favorably. Therefore they are more strongly and deeply affected by karst processes than the limestones of the second group, which are characterized by varying degrees of bituminosity. True, among the Devonian limestones the Middle Devonian limestones stand out sharply; in the area of the Artyshta siding they possess a high degree of karstification, as is proven by the presence in them of a large number of karst forms and springs of large discharge. This phenomenon must be explained by the strong tectonic disturbance of the limestones of the indicated area, which are located in a zone of transverse and longitudinal faults that promote intensive karst formation.

Hydrogeological Features of Karst

The general water-bearing capacity of the geological formations of northeastern Salair has been treated in the works of A. S. Polinovsky (14) and P. M. Bolshakov (4). Therefore we shall not dwell here on this question. We shall consider only the hydrogeological features of the Salair karst, which have been very weakly reflected in the literature. The material presented below does not claim exhaustive completeness in illuminating the question addressed and concerns it only in general outline. The varying degree of intensity of karst formation in the limestones has been reflected in the hydrogeological features of the karst. In terms of water abundance, as well as in degree of karstification, the carbonate rocks of the region may be divided into two groups. The first group includes the Cambrian limestones; the second, the Silurian and Devonian limestones.

Cambrian Limestones

The Gavrilovka limestones, strongly karstified and fissured, present favorable conditions for the accumulation and circulation of fissure-karst waters. In this connection, the most water-bearing rocks of the region are the Gavrilovka limestones. Fissure-karst waters form springs with concentrated discharge and large flow rates. Such springs not infrequently give rise to brooks and small rivers. Thus, the brook flowing through Guryevsk, the left (western) headwaters of the Golodaika River, and others are formed by springs emerging in the field of development of karstified limestones, with discharge up to 36–40 l/sec. Some of the springs are confined to a characteristic relief level, representing the surface of the first terrace (Nos. 29, 30, 31, 38, 39, and 130); another part of them is confined to various points of the relief located within the upper reaches of valleys (springs Nos. 3, 84, 85, and 101) or below the water level of rivers. The noted springs more often have a derivative type of emergence. But there is no reason to doubt the genetic connection of these springs with the limestones, since at the springs or near them—

in them coarse-clastic material is always found, consisting predominantly of blocks of limestone, or else bedrock outcrops of the latter. At the contact of the water-bearing Gavrilovo limestones with water-resisting shales, or with rocks that are less water-bearing than the Gavrilovo limestones (sandstones and conglomerates), conditions are created for the formation of dam-type springs. This situation is well illustrated by Fig. 5, where it is shown that fissure-karst waters, encountering on their path an impermeable barrier of green-violet rocks of the Middle Cambrian, produce the characteristic Guryevsk dam-type spring.

The uneven karstification of the Gavrilovo limestones leaves its mark on their water abundance. Springs Nos. 84 and 85, with a total discharge of 40 l/sec, are confined to the strongly karstified limestones of the Arinichevo mine. Another part of the limestones, affected to a lesser degree by karst processes, has somewhat reduced water-bearing capacity. Thus, in the limestones near the village of Gavrilovskoye, 5 springs emerge with a concentrated outflow, but already with a reduced discharge, reaching as much as 6.23 l/sec (spring No. 30). Finally, hematitized and silicified limestones, which have no karst cavities, display weak water-bearing capacity, forming springs with a small discharge that does not exceed 0.3 l/sec (spring No. 21). The high degree of water-bearing capacity of the karstified limestones was proved by the sinking of shaft 2-bis of the Urskii mine of Zapsibzoloto¹. When the mine intersected the pebble bed, groundwater was encountered at a level of 8 m from the ground surface. In the course of driving the pebble bed, the inflow of water reached 8.3 l/sec. After the limestones with fully developed karst channels were opened, the inflow of water increased to 54.4 l/sec, causing difficulties in carrying out the mining work. The inflow value of 54.4 l/sec was obtained with a lowering of the water level by 15 m. The Upper Cambrian Khomutino limestones, which in lithological structure and karstification are analogous to the Gavrilovo limestones, contain fissure-karst waters discovered in two wells sunk in the village of Gorskino, with a depth to the water level of 3.75–4 m.

Silurian and Devonian limestones.

The Upper Silurian Arinichevo and Pesterevo limestones of the Koblenets horizon, to a considerable extent bituminous and weakly karstified, did not show any noticeable water-bearing capacity. In these limestones, apparently, fissure waters predominate; draining into the Ur River and ravines, they do not yield any appreciable springs. The Krekovo limestones of the Zhedin horizon, and especially the Middle Devonian limestones (Salairka and Karachkino), affected by karst processes, are characterized by comparatively increased water-bearing capacity. Within the area of distribution of the Krekovo limestones, several springs were recorded. Springs with a small discharge were found at the foot of the left bedrock bank of the Salairka River and along the left bank of the Ch. Bachat River near the Krekovo mill. In addition, on the right bank of the Ch. Bachat River, 40 m above the small bridge thrown across the river near the Guryevsk dairy farm, a concentrated outflow of a spring with a discharge of 0.3 l/sec was recorded in the rubble of the Krekovo limestones.

The Middle Devonian Salairka limestones have a higher water-bearing capacity. In them, bedrock and derivative springs were encountered. The bedrock concentrated springs Nos. 11 and 12 are confined to gray lumpy limestones with karst forms, which are found in the form of funnels along the left bank of the Salairka River in the vicinity of the village of Salairka. From

of these, spring No. 12 has a discharge of 1.5 l/sec (6/VIII—36). In most cases the Karachkino limestones do not differ in water-bearing capacity from the Salair limestones. Exceptionally high water-bearing capacity of the Middle Cambrian limestones was established by S. G. Beyrom (2) and by us along the rivers Baskuskan and Kara-Chumysh. Here, springs with discharges of 20–25 l/sec are associated with strongly karstified limestones, often giving rise to brooks and small rivers.

The general aspect of the subterranean hydrography of karst in the limestones of the region is of a roughly uniform character. In the limestones of the first and second groups we did not observe a common (connected) groundwater table of great extent. The outlets of groundwater (springs), recorded at various hypsometric elevations, rather testify to the absence of a connected groundwater table and indicate the existence of several levels of water circulation, which may or may not communicate with one another. The most persistent level of groundwater circulation is located above the surface of the first terrace of the region’s streams. At this level there is a more or less connected table of fissure-karst waters, which, being drained by the hydrographic network, form springs at the level of the surface of the first terrace (springs Nos. 11, 12, 29, 130, etc.). In individual areas the level of karst waters does not coincide with the water horizon of the streams (the Kopanets River, etc.). At the Karachkino limestone deposit the level of karst waters lies 27.6 m below the water horizon of the Ch. Bachat River.

The regime of karst waters has been poorly studied. The hydrometric observations carried out show that their abundance depends considerably on meteorological conditions. The degree of this dependence is complicated by the geological and topographic setting in which the karst waters are formed. The discharge of large springs associated with Cambrian limestones (springs Nos. 3 and 130) undergoes a gradual fluctuation by seasons of the year.

The Salair spring (spring No. 130) in spring and during rainy periods has a discharge of 15–16 l/sec, which in drought and in winter decreases to 7–8 l/sec; i.e., the ratio of maximum to minimum is 2:1. According to fragmentary observations, the discharge of the Guryevsk spring during the noted periods varies from 28 to 40 l/sec, rarely reaching 70 l/sec. This amplitude of fluctuation in spring discharge indicates a comparatively slight change in the abundance of fissure-karst waters over the season of the year. An explanation of this phenomenon is provided by study of the geological structure in the water-feeding area. Within the latter, the limestones and karst forms are overlain by a cover of loose deposits, which hinder the rapid percolation of surface waters downward, thereby regulating the replenishment of the reserves of fissure-karst waters. Sharper fluctuations in the abundance of karst waters occur in areas where exposed limestones are distributed, or in areas where open collapse dolines are present. In this case the entry of atmospheric precipitation and surface waters into the depths takes place rapidly, as a result of which both the groundwater level and the discharge of springs rise sharply. Thus, for example, S. G. Beyrom (2) indicates that the discharge of some springs of the Devonian limestones fluctuated within considerable limits, varying from fractions of a liter per second in the dry season to 8.6 l/sec in the rainy period, which is characteristic of springs possessing a small discharge. Springs of the Devonian waters with large discharges, such as the Artyshkinsky spring, located in the upper reaches of the Baskuskan, change their discharge less sharply by seasons of the year. In the rainy summer of 1939 the Artyshkinsky spring had a flow of 25–30 l/sec, which in January 1940 dropped to 15–18 l/sec. Analyzing the data noted, it should be emphasized that the regime of the waters of the covered karst of Salair differs sharply from the regime of the waters

classical regions of open (Mediterranean and Crimean) karst. Whereas at the Ayan spring, located in the Mountain Crimea region, depending on the season the ratio of maximum discharge to minimum is 600:1, at the Guryevsk spring in Salair this ratio does not exceed 3:1.

In qualitative terms, the karst waters of northeastern Salair are characterized by low mineralization (see Table 2).

Table 2.

Results of chemical analysis of karst waters

The waters of the Cambrian limestones have a dry (solid) residue of up to 260 mg/l and a total hardness of 12.13–12.65 German degrees. Only in mine 2-bis, where artificial mineralization was partly created, is the dry residue of the water 300 mg/l and the total hardness 15.57 German degrees. The total hardness, caused by the high content of calcium and magnesium ions, consists of carbonate and permanent hardness, with the former predominating. Anions of strong acids (SO₄ and Cl) are absent from the water or occur in insignificant amounts due to artificial contamination (mine 2-bis). According to chemical analyses, the waters of the limestones are entirely suitable for drinking and technical purposes. The water temperature lies within the range of 4–8°C. The waters of the Middle Devonian limestones, sampled to an insufficient extent, are characterized by a dry-residue content of 234.14–359.2 and by elevated total hardness, which reaches 16.8 and more German degrees; this accounts for the insufficient suitability of these waters for technical purposes. The abundant water yield of the Cambrian limestones and the high quality of the karst waters are the basis for the full water supply of the Salair mines (spring No. 130) and the drinking-water supply of the workers’ settlement of the town of Guryevsk (spring No. 3). For drinking purposes, the waters of large Devonian springs in terms of discharge, associated with the Bas-Kuskan and Kara-Chumysh rivers, can also be used successfully.

In addition, one cannot fail to touch upon the harmful aspect of karstification and the high water yield of the limestones in two practical questions.

First, the exploitation of the district’s mineral resources (polymetals, gold, etc.) is often hampered by a considerable inflow of karst waters into mine workings, as was shown by the example of mine 2-bis of the Ursk deposit. Especially urgent is the question of the amount of water inflow into mine workings on the deep levels of the Salair ore deposit, which lie close to a mass of karstified rocks. An answer to this question has not yet been given, since no special hydrogeological work has been undertaken to determine the water inflow. Second, the presence of open karst forms in the rocks may cause difficulties in railway construction along the Altai–Kuzbass route, which passes through an area of Devonian karstified limestones. Consequently, the problem of studying Salair karst acquires very great practical significance and is one of the urgent problems of hydrogeological and engineering-geological investigations in the district. In light of the tasks posed, further investigations should be directed toward clarifying the depth of penetration of underground karst, the volume and character of cavities in the limestones, and the regime of karst waters. In this connection, the complex of investigations in the district should include: detailed engineering-geological mapping at a large scale (from 1:5000 to 1:50000), geological prospecting, and geophysical work.

MAIN CONCLUSIONS

1. Salair karst should be assigned to the covered, or Central European, type of karst regions. The karst is covered both by loose deposits and by bedrock non-carbonate rocks.

2. The morphological forms of karst in the district include: sinkholes, basins, caves, dry (dead) valleys, and dry ravines. The surface forms of karst are closely connected with underground (deep) karst. The forms of deep karst are expressed by caves, channels, and fissures that descend into the limestones, being partly filled with red-earth weathering products and fragments of bedrock. In separate areas, deep karst may be developed 80–90 m below the water level in the rivers of the district.

3. The processes of karst formation, which have affected almost all the limestones of Salair, are characterized by varying degrees of intensity. According to the intensity of karst formation, the limestones of the district are divided into two main groups. The first group includes Cambrian limestones; the second comprises Silurian and Devonian limestones. In the pure Cambrian limestones, the factors favoring karst formation were most favorably combined. Therefore they are more strongly and more deeply affected by karst than the limestones of the second group. It is true that in some areas the Devonian limestones, cut by a large number of transverse and longitudinal tectonic fissures, are also strongly karstified.

4. The varying degree of intensity of karst formation in the limestones has been reflected in the hydrogeological features of the karst. The Cambrian limestones, strongly affected by karst, possess increased water abundance, forming frequent spring outlets with discharges of up to 36–40 l/sec, whereas the Silurian and Devonian limestones are less water-bearing. Only the Devonian limestones in the area of the rivers Baskan and Kara-Chumysh show high water abundance, where the discharge of springs reaches up to 25 l/sec.

5. The general aspect of the underground hydrography of the karst is approximately uniform in character. In the limestones of the first and second groups we did not observe a common (connected) groundwater table of great extent. Springs recorded at various hypsometric elevations rather indicate the absence of a connected groundwater table,

in the limestones and indicate the existence of several levels of water circulation, which may or may not communicate with one another. The most sustained level of circulation of underground waters is situated above the surface of the first terrace of the district’s streams. This level has a more or less connected water table of fissure-karst waters, which, being drained by the hydrographic network, form springs at the level of the surface of the first terrace. In individual sectors the level of the karst waters does not coincide with the water horizon of the streams (the Kopanets River, etc.).

1. The regime of the waters of the closed karst of Salair differs sharply from the regime of waters in the classical regions of open (Mediterranean and Crimean) karst. If at the Ayan spring (Mountain Crimea), depending on the season of the year, the ratio of maximum discharge to minimum discharge is 600:1, then at the Guryevsk spring in Salair this ratio does not exceed 3:1.

2. In qualitative terms, the karst waters of the district are characterized by low mineralization. The waters of the Cambrian limestones, having a dry residue of 220–300 mg/l and a total hardness of 12.13–12.65 German degrees, are quite suitable for drinking and technical purposes. The waters of the Devonian limestones have a total hardness of up to 16.8 and more German degrees, in view of which they are not sufficiently suitable for technical purposes. The high water-bearing capacity of the Cambrian limestones and the good quality of the karst waters are the basis for the complete water supply of the Salair mines and the drinking-water supply of the workers’ settlement of the city of Guryevsk.

3. The karstification and high water abundance of the limestones have a negative effect in the solution of a number of practical questions. First, the exploitation of the district’s mineral resources is often hampered by a significant inflow of karst waters into mine workings. Especially urgent is the question of the amount of water inflow into the mine workings on the deep levels of the Salair mine, which lie close to a massif of karstified rocks. An answer to this question has still not been given, since no special hydrogeological work has been undertaken to determine the inflow of water. Second, the presence of hollow karst forms in the rocks may cause difficulties in railway construction along the Altai–Kuzbass route, which passes through the area of Devonian karstified limestones. Consequently, the problem of studying the Salair karst is not only of scientific interest, but also acquires very great practical significance and is one of the most urgent problems of engineering-geological and hydrogeological investigations in the district. In light of the tasks posed, further investigations should be directed toward clarifying the depth of penetration of underground karst, the volume and character of cavities, and the regime of karst waters. The complex of investigations of the district’s karst must include: detailed engineering-geological surveying on a large scale (from 1:5000 to 1:50000), geological-prospecting and geophysical work.

LIST OF LITERATURE USED

1. Barkov, A. S.—Study of karst on the Samara Bend as applied to solving the problem of the Volga construction project. First All-Union Hydrogeological Congress. Third collection, 1933.

2. Beirom, S. G. and Mitgarts, L. B.—Preliminary report on hydrogeological survey in map sheets Nos. 45–65—ABG. Archives Department of ZSGT, manuscript, 1932.

3. Bolshakov, N. M.—Karst of Northeastern Salair. Vestnik ZSGT, No. 1, 1938.

4. The same—Groundwater of Northeastern Salair. Vestnik ZSGT, No. 2, 1938.

5. Butkevich, E. V.—Report of the Guryevsk geological-prospecting party. Stalin Metallurgical Combine, manuscript, 1935.

6. Volodin, A. G. and Predtechensky, A. A.—Report on the work of the Ursk-Salair party, 1934. TsNIGRI, manuscript, 1935.

7. Ermolaev, S. S. and Popov, G. G.—Materials on the study of the Salair bauxites. Archives Department of ZSGT, manuscript, 1936.

8. Katzer, F.—Karst und Karst hydrographe. Sarajevo, 1909.

1. Kruber, A. A.—The karst region of the Mountain Crimea. Zemlevedenie, book 1–2, supplement, 1915.

2. Kuzmin, A. M. and Khristoforov, A. V.—The Karachkino limestone deposit of the Guryev District. Stalinsk, manuscript, 1935.

3. Lazutkin, P. S., Nalivkin, D. V., Rzhonsnitskaya, M. A. and Yavorsky, V. I.—The Devonian of Salair. Problems of Soviet Geology, No. 8, 1936.

4. Lopushinsky, P. M.—A geological-industrial sketch of a sector of the Salair polymetallic deposits. GRB of the Salair mines, manuscript, 1936.

5. Nudner, V. A.—Explanatory note to the topographic map of the Baskuskan limestone deposit. Fund Department of ZSGU, manuscript, 1936.

6. Polinovsky, A. S.—Groundwater of the region of the Salair mines. Vestnik ZSGT, No. 2, 1935.

7. Radugin, V. K.—A geological sketch of the Tom’-Chumysh region of the Salair Ridge. Izvestiya of the Siberian Branch of the Geological Committee, vol. VII, issue 5, 1927.

8. Sawicki, L.—Ein Beitrag zum geographischen Zyclus im Karst. Geographische Leitschrift, 1909.

9. Speransky, B. F.—On the conditions of gold content of the Salair Ridge. Vestnik ZSGRT, issue 6, 1933.

10. The same, and Vinkman, M. K.—On the geology of the NE margin of the Salair Ridge. Fund Department of ZSGT, manuscript, 1935.

11. Tebenkov, V. P.—Some data on karst phenomena in the Kizel coal-bearing district. Proceedings of the Karst Conference, Glavugol’, 1935.

12. Tikhomirov, K. K.—The significance of karst in hydrogeology. First All-Union Hydrological Congress. Collection 7, 1933.

13. Tolstikhina, M. M.—Groundwater and karst phenomena in the central part of the Ufa Plateau. Izv. VGRO, 21, issue 92, 1932.

14. Usov, M. A.—Formations of mineral resources of Salair. Vestnik ZSGT, No. 4, 1933.

15. The same—Elements of the geomorphology and geology of unconsolidated deposits. Publ. ZSGT, 1934.

16. The same—Phases and cycles of tectogenesis of the West Siberian Territory. Publ. ZSGT, 1936.

17. Einor, O. L.—Materials on hydrogeology and karst phenomena in the southern part of the Kizel district in the Urals. ONTI, 1936.

18. Yurmazov, A. S.—On the prospects for the development of gold mining in the Salair Ridge. Vestnik ZSGRT, issue 6, 1933.

19. Yavorsky, V. I.—The Devonian of the southwestern margin of the Kuznetsk Basin. GONTI, 1938.

20. Yatsuk, V. I. and Zablotskaya, M. A.—Report on exploration work at the second Baskuskan limestone deposit in 1936. Fund Department of ZSGT, manuscript, 1937.

1. Shaft section 3.8 × 3.5 m. ↩