The Docambrian and Cambrian of the Cheposh Reference Area in the Altai Mountains

A. F. Belousov

(Presented by Professor K. V. Radugin)

The area includes the vicinity of the villages of Cheposh, Ust-Sema, Barangol, and Ust-Muna. A. M. Nenakhov carried out a survey of the area here in 1930, distinguishing Cambrian and Docambrian strata. In 1941 the area was mapped and subsequently was visited many times by M. K. Vinkman. In 1950 A. F. Belousov compiled a more detailed map with a substantially different interpretation of the structure of the area; until 1959 he made several further thematic investigations of the area. In 1958 A. I. Alyusov carried out a geological survey for lithological-stratigraphic purposes in the southern part of the area. In 1949–59 paleontological collections were made here by L. I. Egorova, O. K. Poletaeva, P. S. Krasnopeeva, S. V. Chernysheva, M. F. Romanenko, and others.

Tectonics of the Area

As shown on the schematic geological map (Fig. 1), in the vicinity of the settlement of Ust-Sema there is established a synclinal structure, complicated by faults, with a plunge to the NNE. In the southeastern limb, the strike of the bedding elements does not coincide with the submeridional direction of the disjunctive sutures, and therefore the normal stratigraphic relationships of the strata are clearly discernible.

The relationships of the strata in the northwestern limb have been more strongly reworked by disjunctive dislocations, the system of displacers of which, as in the remaining parts of the area, has been revealed by surface study. The displacers are vertical or dip steeply westward. This series of faults appears to be a zone of complex development with large and repeated displacements of slices, since suites separated in stratigraphic position occur in immediate proximity. The nearly vertical bedding elements of the strata in this zone predominantly dip to the E and SE, toward the axial zone of the syncline; in the same direction the belts of outcrop of the strata change from older to younger.

A complex disjunctive structure, according to data of Yu. A. Speit and the author, is also established in the lower reaches of the B. Muna and Munushka rivers. Along the Munushka River and on its right watershed, rocks of the carbonate-shale-siltstone stratum tectonically border the effusive-sedimentary stratum. The latter here is composed of rocks that are analogous

rocks of the near-axial part of the Ust-Sema synclinal structure, differing from them in more sharply manifested dislocation and thermal metamorphism (epidotization, chloritization, etc.). The complexity of the disjunctive tectonics in this area is due to the convergence of the already described bundle of faults of N–E strike and another series of seams approaching from the southeast.

Fig. 1. Geological map of the Cheposh area (compiled by A. F. Belousov).
1. Baratal suite (Precambrian). Limestones, dolomites, silicilites, shales, greenstone porphyrites. 2. Manzherok suite (ancient porphyrite) (Precambrian). Plagioclase and pyroxene-plagioclase porphyrites, conglomerates, tuffs, shales, limestones, dolomites. 3. Kayanchin suite \((Cm_1)\). Limestones, marls, shales, basal conglomerates (distinguished). 4. Ust-Sema suite \((Cm_1—Cm_2)\). Augite, pyroxene-plagioclase and plagioclase porphyrites, tuffs, conglomerates, sandstones, shales, limestones. 5. Green-colored unit \((Cm_2)\). Metamorphic sandstones, shales, limestones, porphyrites. 6. Gabbro-diorite intrusion. 7. Valley loose deposits. 8. Individual carbonate marker horizons. 9. Disjunctive contacts. 10. Localities of fauna. 11. Elements of nappe occurrence.

The latter accompanies the disjunctive SW boundary of the green-colored unit of sandy-clayey composition with beds of marbles and effusives, which within the area is characterized by strong dislocation metamorphism. Within the field of the neighboring effusive-sedimentary unit, the faults are accompanied by strong crushing, strong schistosity, and sometimes by the transformation of effusives into porphyritoids. The fault planes are oriented approximately vertically or with steep dip—

to the NE. This bundle of faults, extending southward, crosses the Katun valley between the villages of Cheposh and Uznezya.

Through the lower reaches of the rivers B. Cheposh and Emurla there passes a belt of rocks of the effusive-sedimentary sequence, in the sedimentary and lava rocks of which a dip to the NE, E, and ENE is observed in almost all cases. The section of the sequence is asymmetrical. In its western part chiefly augite and pyroxene-plagioclase porphyrites of gray-green and lilac colors are exposed; in the eastern part the porphyrites have a more considerable participation of tuffites, limestones, sandstones, and shales. In the upper part of the belt there was observed a relationship of differential schistosity to bedding characteristic of the normal occurrence of beds. All this indicates the general homoclinal occurrence of the sequence. On the west the effusive-sedimentary rocks of the belt border a large field of the carbonate-shale-silicilite sequence along a weakly diagonal fault. Along it, in the rocks, intense foliation, mylonitization, formation of porphyroid structures, and small-scale folding in limestones are observed.

Fig. 2. Geological map of the 3–4 km section of the Chemal tract
(Compiled by A. F. Belousov, partly using data of A. I. Alyusov).

1. Manzherok (ancient porphyrite) suite. Plagioclase and pyroxene-plagioclase porphyrites, conglomerates, tuffites, tuffs.
   2–5. Kayanchin suite ($Cm_1$): 2—basal conglomerates; 3—thin-bedded clayey limestones; 4—massive marbled limestones; 5—marls, clayey shales.
   6–8. Ust-Sema suite ($Cm_1$—$Cm_3$): 6—basal conglomerate-breccias; 7—massive marbled limestones; 8—augite porphyrites, conglomerates, tuffites, tuffs, marls, shales;
2. Terrace deposits.
3. Disjunctive contacts.
4. Elements of bedding attitude.
5. Localities of fauna.

The internal structure of the field of the carbonate-shale-silicilite sequence is generally synclinal, of near-meridional strike. The limbs of this structure are complicated by small folds—

...and locally, folding. At the western edge of the belt, in the walls of the Katun’, an anticlinal bend is observed, with partly overturned bedding of the strata in the western limb.

West of the field of the carbonate–shale–silicilyte sequence, the steeply dipping SW limb of the Ust’-Sema synclinal structure crops out. The limb is dissected by submeridional faults with steep and vertical displacers (Fig. 2). Displacement of marker horizons indicates the essentially strike-slip character of the faults. The faults are often accompanied by small folds and folding in packets of thin-bedded calcareous–argillaceous rocks. For the latter, fine disharmonic drag folding is also very characteristic, disappearing in the underlying and overlying packets of more massive rocks (crypto-bedded limestones, conglomerates). The strike and dip of the disharmonic folds usually coincide with the submeridional direction of cleavage developed in the rocks.

In the Cheposh area, a number of contradictions in the interpretation of stratigraphic relationships are connected with insufficient attention by geologists to the deciphering of disjunctive tectonics.

Stratigraphy of the area

The oldest is the sequence that borders the rocks of the Ust’-Sema syncline on the NW and SE. The margins of the field of this sequence in the vicinity of the village of Cheposh are composed mainly of limestones with silicilytes and, locally, dolomites and siliceous shales. On the right bank of the N. Cheposh River, where the axial zone of the synclinal structure is indicated, an alternation is observed of carbonaceous limestones, silicilytes, argillaceous, calcareous-argillaceous, and siliceous shales, dolomites, with rare covers of greenstone spilitic plagioclase and diabase porphyrites and tuffites. The approximate thickness of the part of the suite represented here is 2500 m.

Manzherok (ancient porphyrite) suite

Over a considerable thickness and with relatively slight disturbance, a normal section of the suite is exposed in the SW limb of the Ust’-Sema synclinal structure. However, the base of the suite here, as in other parts of the area, is truncated by a fault of considerable amplitude.

On the right bank of the Katun’, according to data from a detailed study of the section, the upper part of the suite is subdivided into the following members (from bottom to top).

1. Aphanites and amygdaloidal porphyrites with individual lenses of dolomite and limestone; upward, over a thickness of more than 30 m, limestones with large spherical algae occur, with packets of greenish-gray argillaceous and marly shales. The total thickness of the member is 170 m.

2. Effusive conglomerate-breccias, passing upward into coarse tuffites with covers of aphanites and amygdaloidal porphyrites (including lilac-colored ones), rare lenses of limestones, silicilytes, and argillaceous shales — 360 m.

3. Effusive conglomerate-breccias, higher up replaced by effusive conglomerates and tuffites, with packets of tuff-breccias (including those with an argillaceous cement) and covers of aphanites; upward, over a thickness of 30 m, oolitic limestones, silicilytes, carbonaceous argillaceous shales crop out. The total thickness is 390 m.

4. Aphanites and amygdaloidal porphyrites, occasionally lilac-colored, with packets of effusive conglomerate-breccias and tuff-breccias, replaced upward by conglo-

marls, gravelites, tuffites, and clay shales with interbeds of oolitic limestones — 525 m.

1. Effusive conglomerate-breccias, with rare fragments of limestones and silicilites, replaced upward by effusive conglomerates, gravelites, and tuffites with separate packets of clay shales and lenses of limestone; sheets of aphanites and amygdaloidal rocks (substantially in the lower part) — 310 m.

The total thickness of the part represented is over 1700 m.

In view of the absence of any sufficiently reliable stratigraphic contacts between the Baratal and Manzherok formations, the question of their relations in the Cheposh area is not resolved, although there is an opinion about angular unconformity and even about a sharply discordant relationship of the folds between them in the area (M. K. Vinkman, A. I. Alyusov).

Kayanchinskaya Formation

The section of the formation has been exposed through its full thickness in the eastern limb of the Ust-Sema synclinal structure; moreover, until recently the greatest attention was paid to the right-bank, strongly disturbed area directly adjoining the Chemal tract (Fig. 2). Good outcrops of rocks of the formation occur on both sides of the valley and along the banks of the Katun immediately at the water’s edge.

From bottom to top, in the section of the formation, according to data refined in 1959, the following are distinguished:

1. Boulder and pebble conglomerates, passing upward into gravelites and gray rhythmically bedded sandstones, aleurolites, clay shales, and marls — 175–200 m.

2. Dark-gray and gray flaggy limestones, medium- and thin-bedded, often with rhythmically included aleurolite-clayey, marly, and siliceous-clayey interbeds — 275–300 m.

3. Dark-gray and gray massive marbled limestones — 400 m.

4. Gray thin-bedded marls with interbeds of limestones, gray clay shales, calcareous sandstones, aleurolites, and rare thin lenses of fine-pebble limestone conglomerates — 135–160 m.

The total thickness of the sequence is 985–1060 m.

The conglomerates of the thick basal packet of the formation contain pebbles and boulders of carbonized and light marbled limestones, silicilites, siliceous and phyllitized clay shales, greenstone porphyries, diabases and tuffs, conglomerates, sandstones and tuffites; diorite-porphyries, albitophyres, vein quartz, and jaspers are encountered sporadically among the pebbles. The cement of the conglomerates is sandy, mictitic, sometimes substantially graywacke, often strongly calcareous.

On the left side of the Katun, below the mouth of the Sema River, in the disturbed western limb of the synclinal structure, horizons of augite amygdaloid, coarse graywacke tuffites, and conglomerate-breccias have been noted among the limestones of the formation with archaeocyaths.

The occurrence of the Kayanchinskaya Formation on the rocks of the Manzherok Formation is recognized by all investigators as unconformable. At the base of the basal conglomerate, indistinct angular and azimuthal unconformities are outlined. In the latter, pebbles of rocks of both underlying formations exhibit relict tectonic fracturing. Upon detailed study and comparison of the section of the Manzherok Formation with the neighboring younger formations of the area, a considerably stronger ob-

…dislocation metamorphism of rocks (cataclasis, deep greenschist alteration).

The general features of the normal section of the suite make it possible to represent it as a transgressive complex.

Recently M. K. Vinkman proposed dividing the Kayancha suite in the area into three separate suites: 1) basal conglomerates with bedded limestones, 2) massive limestones, and 3) gray marls. However, there are as yet no convincing data, and above all no reliable paleontological correlations, that would allow one to assert that these relatively thin parts of the section will have the significance of suites for the Altai region. As evidence for the separation of the massive limestones, M. K. Vinkman cites the observation made by A. B. Gintsinger in an outcrop beneath the left watershed of the Katun, north of the Shashkunar River, where bedded limestones adjoin at an acute angle almost massive limestones without any basal clastic formations. This observation, in our view, reflects a sharply local structure and is insufficient proof of an angular unconformity and deep erosion. Angular discrepancies in a number of places along the contact are caused by the already mentioned disharmonic folding in the bedded limestones. This folding is absent in the overlying massive limestones and in the thick-bedded underlying conglomerates. Together with the bedded limestones, sills of diabase porphyrites, synchronous with the effusions of the younger Ust-Sema suite, were crumpled into disharmonic folds. This proves the late age of the locally complex folding in the bedded limestones. On detailed tracing along the right bank of the Katun, in undisturbed areas the boundary between the bedded and massive limestones in the outcrops is not everywhere sharp; the bedding in the limestones does not disappear immediately (for this reason, apparently, the boundary is drawn differently on separate maps by different authors). The massive limestones of the Cheposh area can, with a certain degree of probability, be correlated with the upper limestone member of the Kayancha suite of the Elanda area (located 30 km south of Cheposh). At the base of the latter there are no signs of unconformity, and, on the contrary, with parallel bedding there is a transitional horizon with interbedding of terrigenous and carbonate rocks.

In earlier publications, the fauna of archaeocyaths and trilobites collected in the deluvium near the cliffs of massive limestones of the third member of the suite was assigned to the Kayancha suite of the area, and in part also fauna that should already be assigned to the lower horizons of the overlying Ust-Sema suite.

In 1958–59, workers of the West Siberian Geological Administration (A. I. Alyusov, M. F. Romanenko), of SNIIGiMS (M. K. Vinkman, L. I. Egorova), and of the Academy of Sciences of the USSR (L. N. Repina, I. T. Zhuravleva) carried out repeated and new paleontological collections at numerous bedrock localities, which make it possible to refine the age of the suite and of its various horizons. Here, in addition to data cited earlier, we use some new data on the fauna. M. K. Vinkman’s group found, in the lower part of the member of bedded limestones, archaeocyaths permitting correlation of the member with the Kameshkov horizon. In these same limestones A. I. Alyusov discovered algae Archaeospongia.

From bedrock outcrops of massive limestones, A. G. Pospelov, on collections by A. I. Alyusov and M. F. Romanenko, identified the archaeocyaths Tercyathus cf. oviculus Krasn., Retecyathus cf. kuzmini Vologd., Archaeocyathus sp., Ethmophyllum catunicum Krasn., Ajacicyathus jizkii (Toll), Archaeofungia (?) sp., Loculocyathus sp., Dictiocyathus sp., Claruscyathus sp., Terofungia sp., Tercyathus sp.

Previously, from the dolomites of the massive limestones, P. S. Krasnopeeva also identified some other species of the genera Tegerocyathus and Ajacicyathus, as well as representatives of Clathrocyathus. The general aspect of the archaeocyath fauna proves to be more ancient in comparison with the youngest archaeocyath complex of Siberia—the Obruchev complex.

Among the trilobites collected together with archaeocyaths in the dolomites of the massive limestones, L. I. Egorova indicated representatives of the characteristic Lower Cambrian genera Bergeroniellus certus Jegor., Bonnia sp., Binodaspis laboriosus Jegor., Weymouthia minor Jegor., W. tchernishevae Jegor., Cobboldia altaica Polet., together with forms of genera extending into the Middle Cambrian (Edelsteinaspis ornatus Lerm., E. gracilis Lerm., Chondragraulos minussensis Lerm., Granularia obrutschevi Polet., Gaphuraspis apertus Jegor., Kooteniella slatkowskii (Schm.), Kootenia magnaformis Jegor., Namanoia sp., Erbia granulosa Lerm., Pagetia catunica Polet., P. infirma Jegor.). Although the list of trilobites requires clarification, it permits the assignment of the Kayancha suite with the member of massive limestones to the Lower Cambrian.

Ust-Sema Suite

This name, originally proposed by M. K. Vinkman (1948), we retain for the effusive-sedimentary suite composing the middle part of the Ust-Sema synclinal structure. Other names for the suite proposed in recent times (Suyaryk, etc.) are not necessary and violate the principle of priority. The Ust-Sema suite of the Cheposh area represents the lower units of a thick effusive-sedimentary series (“Kaim”).

A composite section of the suite may be presented in the area in the following form (from bottom to top).

1. Greenish-gray, rarely reddish, porphyritic and polymictic sandstones, gravelites, conglomerates, conglomerate breccias with subordinate members and interbeds of gray aleurite-clayey and marly rocks, members and lenses of marbled limestones, sheets of augite porphyries and tuff breccias—1300 m.

2. Greenish-gray, and in the upper half variegated greenish-lilac, porphyritic conglomerate breccias with subordinate members of porphyritic sandstones and gravelites, sheets of augite, pyroxene-plagioclase, and plagioclase porphyries and tuff breccias—approximately 2500 m.

The total thickness of the effusive-sedimentary accumulations of the suite in the area is about 3800 m. The lower part of the suite, in thickness, composition, and appearance of the rocks, is comparable with the lower part of the Ust-Sema suite of the Elanda area and may be distinguished as its lower subsuite. The upper part may likewise be regarded as a subsuite.

For the coarse-clastic rocks of the suite, including the lower member, a clearly intraformational origin of the material is characteristic. The same is inherent in the sandy rocks of the suite; only in the upper part of the second member, in the sandstones, in addition to porphyritic-graywacke material, is a noticeable admixture of quartz grains observed.

The lower units of the suite reveal interesting structural features. On the steep right bank of the Katun, a large lens (bioherm) of massive reef archaeocyath limestone up to 35 m thick clearly overlies the gray marls of the Kayancha suite, thinning rather sharply eastward. The rocky ridge composed of this limestone extends almost 200 m eastward into the depth of the bank. The limestone, in continuous rocky outcrops, forms a distinct double fold of WNW strike.

of the strike (Fig. 2), owing to which the southeastern edge of the band is greatly widened in plan. In the limestone bed, at the contact with the marls, there is traced a bed of massive conglomerate-breccia with fragments (up to large boulders in size) of gray limestone, marls, and augite porphyrites in a calcareous-graywacke cement. The conglomerate-breccia bed in the southern and southwestern parts of the limestone bed has a thickness of up to 1 m and more and, together with the limestone and the underlying marls, is cut by several meridional dikes of augite porphyrites. In the hinge area of the anticlinal bend of the lens, the bed of conglomerate-breccia sharply increases in thickness to several meters and, taking a southeastern strike, proves to be in the footwall of a unit of variegated, coarse-clastic conglomerate-breccia with a basal sandy-clayey cement, which directly abuts along strike against the blunt western end of the limestone lens. Similar conglomerate-breccias crop out along the strike of the limestone at the eastern pinching-out of the lens, and also cover the bioherm from the north with a unit up to 20 m thick. The total thickness of the conglomerate-breccia with the limestone bioherm is 50 m.

In the bed of conglomerate-breccia underlying the limestone, near the western end of the lens, truncation of beds in gray marls at an angle of 10–15° is directly observed, indicating preceding erosion. This fact, together with the abundance of erosion products of augite porphyrites of the Ust’-Sema type in the conglomerate-breccias, makes it possible to draw clearly, in this area, the base of the Ust’-Sema Formation above the unit of gray marls. It should be noted that 200 m above the mouth of the Suyaryk Creek, at the water’s edge on the right bank of the Katun, stratigraphically above the gray marls, there appears a 50-meter cover of augite porphyrite, and above it follow conglomerate-breccias with yet another 30-meter lens of massive limestone, in which remains of archaeocyathids, trilobites, and brachiopods have been found (Fig. 2).

The limestone bioherm with its abundant fauna, therefore, proves to be included in the basal coarse-clastic unit of the Ust’-Sema Formation, which corrects the earlier constructions of M. K. Vinkman, A. F. Belousov, and others, who assigned this limestone to the upper half of the Kayanchin Formation.

For the present there are no reliable facts that would permit the unconformity and erosion at the base of the Ust’-Sema Formation in this area to be regarded as having the character of a major regional angular unconformity, with possible deposition of the Ust’-Sema Formation on formations older than the Kayanchin (the latter has nowhere in Altai been reliably established). In the area, the gray-marly unit of the Kayanchin Formation, underlying the Ust’-Sema Formation, maintains its thickness without abrupt changes. As will be seen, the age of the fauna from the lower part of the Ust’-Sema Formation and of the massive limestones of the Kayanchin Formation is also close.

M. K. Vinkman [2] regards the unconformity at the base of the Ust’-Sema Formation as a record of a phase of intense folding, referring in this connection to fragments of gray thin-bedded laminated marls occurring in the lower horizons of the Ust’-Sema Formation. The thin-bedded gray marls, according to the observations of the author, and also of O. K. Poletaeva, in the lower part of the Ust’-Sema Formation constitute synchronous submarine-slump plastic “roll-downs” of various forms and sizes (short nodules, etc.).

In the section of the lower part of the second, effusive-sedimentary unit of the formation, horizons of coarse-clastic conglomerate-breccias are observed, with blocks up to several meters across of massive limestones containing archaeocyathids and trilobites. The blocks and boulders of limestone should naturally be regarded as the result of destruction of nearly synchronous intra-

formation reef banks. Undoubtedly belonging to the middle horizons of the lower part of the Ust’-Sema Formation are lenses and beds of marbled limestones with archaeocyaths, trilobites, and brachiopods, exposed in the lower part of the left bank of the Katun’, 700–900 m above the mouth of the Sema River.

A. G. Pospelov, from the above-described lower limestone lens on the right bank of the Katun’ (opposite km 3200–3300 of the Chemal road), identified Ethmophyllum catunicum Krasn., Ethm. aff. potetaevae Vologd., Tegerocyathus edelsteini (Vologd.), Tegeroc. aff. erbiensis Krasn., Retecyathus sp., Ajacicyathus sp., Carinocyathus sp., Thalamocyathus sp., Syringocyathus sp. Together with the archaeocyaths, M. F. Romanenko identified the trilobites Kootenia sp., Koot. vologdini Lerm., Koot. magnaformis Jegor., Koteniella sp., Kooteniella slatkowskii Lerm., Granularia sp., Granularia obrutschevi Polet., Edelsteinaspis ornatus Lerm., E. planus Tschern., E. gracilis Lerm., Binodaspis cf. laboriosus Jegor., Gaphuraspis sp., G. apertus Jegor., Ptychoparia sp., Solenopleura (?) sp., Erbia sibirica (Schm.). Brachiopods are present—kutorginids and lingulellids.

From the aforementioned limestone lens 200 m above the mouth of the Suyaryk Creek at the waterline of the Katun’, the same paleontologists identified the archaeocyaths Ethmophyllum sp., Tegerocyathus edelsteini (Vologd.), Tegeroc. cf. bey-buluki Krasn., Retecyathus cf. kuzmini Vologd., Archaeocyathus sp., Archaeocyathus cf. subradiathus (Vologd.), Loculocyathus sp., Erbocyathus sp., and the trilobites Kootenia sp., Gaphuraspis apertus Jegor., Solenopleura sp., Erbia sibirica (Schm.).

The archaeocyaths of both limestone lenses from the lower part of the Ust’-Sema Formation belong to the youngest archaeocyath horizon of Siberia—the Obruchev horizon. The trilobites are represented almost exclusively by forms characteristic of the Elan horizon (stage) of eastern Siberia. The age of both is debatable and is determined as within the upper Lower to lower Middle Cambrian. It should be noted that in the lower part of the Ust’-Sema Formation there are almost no characteristic forms of Lower Cambrian trilobites recorded in the massive limestones of the Kayanchin Formation.

From the numerous limestone boulders and blocks of limestone in conglomerate breccias of peripheral-reef origin and, probably, tuff breccias of the first and second beds, the archaeocyaths Ethmophyllum sp., Tegerocyathus sp., Tegeroc. edelsteini (Vologd.), Tegeroc. cf. erbiensis Krasn., Tegeroc. cf. bey-buluki Krasn., Ajacicyathus sp., Archaeocyathus sp., Erbocyathus (?) sp. have been identified. Predominantly from the same blocks as the archaeocyaths, the trilobites Kootenia sp., Kootenia magnaformis Jegor., Kooteniella sp., Granularia obrutschevi Polet., Erbia sibirica (Schm.), Chondranomocare sp., Ch. minussensis Lerm., Edelsteinaspis sp., E. ornatus Lerm., Gaphuraspis sp., Solenopleura sp., Namanoia sp., Poulsenia cf. granosa Resser, Proerbia sp., Pachyaspis sp., Ptarmigania (?) sp., Solenopleurella sp., Dinesus (?) sp., Olenoides sp., Taxioura sp., Taxioura altaica M. Rom., and kutorginids have been identified.

A higher stratigraphic position (the middle horizons of the lower subformation) is occupied by the fauna locality in the limestone bed in the lower part of the left bank of the Katun’, 750 m above the bridge over the Sema River. From here S. V. Chernysheva identified the archaeocyaths Tegerocyathus cf. edelsteini (Vologd.), Tegeroc. diploperforatum (Vologd.), Tegeroc. cf. abacanensis (Vologd.), Archaeocyathus sp., Archaeoc. aff. latus (Vologd.), Tersia cf. nodosa Vologd.; O. K. Poletaeva identified the trilobites Amecephalina sp., Vinia altaica n. sp.; N. A. Aksarina identified the brachiopods Kutorgina.

References

1. Belousov, A. F. On the section of the oldest metamorphic strata and the upper boundary of the Precambrian of Altai. Proceedings of the Tomsk Polytechnic Institute, vol. 90, 1958.

2. Vinkman, M. K. Structure and stratigraphy of the ancient strata of the Katun horst-anticlinal uplift in Northern Altai. Proceedings of the Mining-Geological Institute, West Siberian Branch of the Academy of Sciences of the USSR, issue 2, 1948.

3. Vinkman, M. K. Stratigraphic scheme of the Precambrian and Lower Paleozoic deposits of the Mountain Altai. Materials on the Geology of Western Siberia, issue 61, Gosgeoltekhizdat, 1958.