On the Stratigraphy of the Devonian in the Central Part of the Mariinsk Taiga (Kuznetsk Alatau)

B. D. Vasil’ev

(Presented by Professor A. G. Sivov)

The Devonian deposits of the basin of the middle course of the Kiya River and its left tributaries (the Kozhukh and Kundat rivers) were studied by us in connection with determining the age of a comparatively young gold-bearing gabbro-syenite intrusion. However, the very presence in the axial part of the Kuznetsk Alatau of thick strata of Devonian age, their stratigraphy, and the features of the structures composed by them deserve attention.

Within the central part of the Mariinsk taiga (Fig. 1), the Devonian is represented by sedimentary and volcanogenic formations, which are divided into two sequences separated by an angular unconformity: a lower (red-colored) and an upper (volcanogenic) sequence. The Devonian deposits have their greatest thickness in the southwest of the area described, in the Palatninskii graben, where they are represented by both sequences and are gathered into large folds of latitudinal trend.

Farther north, in the basin of the Tuluiul River, and farther to the northeast, along the Kozhukh River and the Bodochat stream, the terrigenous deposits of the lower sequence are predominantly distributed. Here they are gathered into a narrow syncline of northeastern trend, complicated by small folds and broken by transverse faults into three large blocks: the Tuluiul, Kozhukh, and Bodochat blocks. The volcanogenic formations of the upper sequence, apart from the Palatninskii graben, are distributed in the zone of the latitudinal Makarak fault near the settlement of Makarak on the Kiya River. They also compose a series of watershed heights between Makarak and the Palatninskii graben.

Questions of subdivision and age of the red-colored and volcanogenic deposits of the area have been resolved in different ways. As early as on the geological map of V. S. Reutovskii and A. M. Zaitsev (1896), the red-colored deposits were distinguished as an independent sequence and were dated conditionally to the Upper Devonian. D. V. Nikitin [9] assigned the volcanogenic sequence of the Palatnaya River basin conditionally to the Lower Silurian, and the red-colored deposits to the Devonian. A. N. Churakov [10] considered the volcanogenic sequence to be Upper Silurian. N. N. Dingel’shtedt [5] conditionally assigned to the Lower Devonian the red-colored deposits in the basin of the Kozhukh River and along the Tuluiul River.

In 1940, A. R. Anan’ev correlated the red-colored deposits of the Kundustuyul with the Devonian red beds of the Taidon region (with flora) and assigned them to the Middle Devonian. The “effusive-conglomerate formation” of the Palatnaya River basin was conditionally assigned by him to the Lower–Middle Devonian \((D_{1-2})\). However, already in 1946 A. R. Anan’ev pred—

proposed a new scheme for the stratigraphy of the Devonian deposits, distinguishing two independent formations separated by a major tectono-denudational break. The lower formation \((D_1)\) included red-colored sedimentary rocks of the southern part of the area (Kundustuyul–Afanasyevka). The volcanogenic formations of the Palatnaya River basin were distinguished by A. R. Ananyev at this stage of the investigations as an independent Palatnaya formation, separated from the underlying red beds by an unconformity.

Fig. 1. Scheme of the distribution of Devonian deposits in the central part of the Mariinsk Taiga. Compiled by B. V. Vasiliev.

Palatnaya volcanogenic unit \((D_2^{1})\):
1 — upper effusive member, 2 — lower tuffaceous member.

Red-colored unit \((D_1^{2})\): 3 — upper coarse-clastic member, 4 — middle fine-clastic member, 5 — lower coarse-clastic member.

6 — pre-Devonian basement rocks

However, for some reason this formation was included by him in the lower formation. The upper red-colored formation was assigned conditionally to the Middle Devonian and combined the red-colored deposits of Tuluyul, Kozhukh, and Bodochat. Thus, while speaking of the recognition of two formations, A. R. Ananyev [3] in fact-

... identified three independent large stratigraphic units separated by unconformities, namely: the lower red-bed suite, the Palatninskaya volcanogenic formation, and the upper red-bed suite, and later repeated this scheme [4].

L. V. Alabin [1], during geological mapping at a scale of 1:200,000, assigned all Devonian deposits of the area to the Telbes series of Lower–Middle Devonian age \((D_{1-2})\), mistakenly regarding the red-bed and volcanogenic formations as facies analogues. The flora first collected by L. V. Alabin in greenish-gray conglomerate-like sandstones on the Kundat River was processed by paleontologists of VSEGEI, N. M. Petrosyan and G. P. Radchenko, who identified: Taeniocrada sp., Psilophyton cf. princeps Daws., Psilophyton goldschmidtii Halle, Psilodendrion sibiricum Lep., Uralia sp.

Later L. V. Alabin [2], in the southern part of the area (Kundustuyul–Afanasyevka), subdivided the Telbes series into two suites separated by an unconformity: the lower—Krasnogorskaya—and the upper—Palatninskaya—thereby confirming the correctness of A. R. Ananyev’s distinction of the lower red-bed suite and the Palatninskaya formation. The question of the upper red-bed suite, which, according to A. R. Ananyev, unites the Devonian sedimentary formations of the Tuluiul, Kozhukh, and Bodochag basins, was not considered by L. V. Alabin.

On the basis of materials obtained as a result of geological mapping and the study of sections, we came to the conclusion that A. R. Ananyev’s upper red-bed suite is an analogue of his lower suite. On what was the distinction of the upper red-bed suite based? The direct age relations of the distinguished suite with the Palatninskaya formation had not been established. A. R. Ananyev based the distinction of the suite on three points:

1) the absence within it of diabase sills, so widely distributed among the red-bed deposits of the southern part of the area, where the lower suite was distinguished;

2) the presence, in the pebbles of basalt conglomerates on the Kozhukh River, of effusives analogous to the effusives of the Palatninskaya formation;

3) the different strike of the folded structures into which the red-bed deposits are gathered: latitudinal in the south (lower suite) and northeastern, up to meridional in the basin of the Kozhukh River (upper suite).

Rejecting the independence of the upper red-bed suite and correlating it with the lower one, we rely on the following materials.

1. Diabase sills are not an exclusive feature of the red-bed deposits of the southern part of the area: we encountered them also in the basin of the Kozhukh River, although in smaller quantity.

2. A comparative study of the Devonian conglomerates along the Kundustuyul and Kozhukh showed that pebbles of effusive rocks are indeed present in their composition, and in the conglomerates of the Kundustuyul (lower suite, according to A. R. Ananyev) there are even more such pebbles than in the conglomerates on the Kozhukh River (upper suite, according to A. R. Ananyev). The effusive rocks in the pebbles are represented by cherry-brown albitophyres, which are characteristic not of the Palatninskaya formation, but of the Precambrian volcanogenic sequence exposed along the Kundat River above the mouth of the Sobolinka River.

3. As for the different strike of the folded structures of the red-bed deposits, this criterion cannot be taken here as a basis for distinguishing a suite, since even within a single belt of red-bed deposits the strike of the structures changes sharply from latitudinal in the basin of the Tuluiul River to meridional at the mouth of the Tiguli River and to northeastern along the Bodochag. The formation of such structures, sharply discordant in strike, in the Devonian deposits of the North Minusinsk...

of the depression was explained in the works of I. V. Luchitskii [7], Ya. G. Kats [6], A. A. Mossakovskii [8], and other geologists as a reflection, in the Devonian sedimentary cover, of block movements of the basement of the depression. In this light, the formation of differently oriented folds in the Devonian red-bed deposits of the Kundustuyul–Kozhukh mobile zone is quite possible as the result of a single phase of folding that caused block movements of individual basement blocks within the zone under consideration.

1. Comparing the stratigraphic columns (Fig. 2) of the red-bed deposits of the basin of the Kundustuyul River (lower suite, according to A. R. Anan'ev), and of the Kozhukh and Tuluyul rivers (upper suite, according to A. R. Anan'ev), it is not difficult to—

Fig. 2. Correlation diagram of sections of the red-bed Devonian deposits of the Kiya River basin.
1 — volcanogenic formations of the Palatninskaya unit; 2 — diabase sills; 3 — cross-bedded sandstones; 4 — argillites; 5 — albitophyres; 6 — sandstones; 7 — conglomerates and conglomeratic sandstones; 8 — basement rocks.

—note that everywhere within the red-bed sequence three major members can be distinguished: a conglomerate–sandstone member, an argillite member, and a predominantly sandstone member. The thicknesses of the lower and middle members are comparable in the individual sections.

1. Finally, on the Kozhukh River opposite the mouth of the Tiguli River, in a large rock exposure, we established the direct superposition of diabase amygdaloidal porphyrites upon the eroded structures of the upper red-bed suite of A. R. Anan'ev.

The materials presented above indicate that, both in the south of the area—at the Kundustuyul–Afanas’evka site—and in the north—in the basin of the Kozhukh River—we are dealing with red-colored deposits of a single stratigraphic position, corresponding entirely to the lower red-colored suite of A. R. Anan’ev. At present there are no grounds for distinguishing an upper red-colored suite. However, we consider it more correct at the present stage of investigation to abandon the name “lower red-colored suite” in favor of the name “red-colored sequence,” taking into account that the thickness and three-member structure of the sequence will subsequently make it possible to distinguish within it, as we think, two pulsational suites corresponding to two large cycles of sediment accumulation.

From this standpoint let us consider the stratigraphy of the Devonian deposits of the area.

Red-colored sequence

In the Palatninskii graben, the red-colored deposits were studied by us in the interfluve of the Bol’shoi and Malyi Kundustuyul, near the eastern boundary of the graben. Here the red-colored sequence is completely exposed across its strike by the Kundustuyul River at a distance of 750 to 2750 m upstream from the mouth of the latter, and also by the M. Kundustuyul River and the Kundat River. Resting unconformably on the weathering crust of syenite-diorites of the Kundat massif and the enclosing rocks of the Lower Cambrian, the red-colored deposits dip northward, with the angle of dip increasing from 34 to 60°, and are unconformably overlain by tuff conglomerates of the Palatninskii volcanogenic sequence (Fig. 2).

The basal beds of the sequence are represented, as a rule, by cherry-red siltstones, which pass upward in the section into coarse-pebble conglomerates; these usually do not have a strictly definite stratigraphic position when traced along strike. Only in the interval of 80–100 m do the conglomerates form a bed persistent along strike within the entire graben.

In the conglomerates, pebbles of intrusive rocks of the Kundat massif, cherry-red albitophyres, and microquartzites predominate. Pebbles of quartz are relatively common. The cement of the conglomerates is basal, calcareous-siltstone.

Stratigraphically above the conglomerates lie coarse-grained red-colored sandstones (150 m), light-yellow arkosic sandstones (120 m), and red-colored medium- and fine-grained sandstones (150 m), separated by sills of diabases of varying thickness.

In the roof of the conglomerate-sandstone member lie light-pink albitophyres, whose thickness on the Kundustuyul River reaches 120 m. They have been traced along strike for a distance of 4 km to the Kundat River, where their thickness decreases considerably. On the M. Kundustuyul River, intersections of the albitophyres by diabases were observed.

Above the albitophyres lies an argillite member, consisting, from bottom to top, of red-colored argillites (100 m), greenish-gray marly argillites (100 m), and again red-colored argillites (70 m). From one another and from the overlying sandstone member they are separated by sills of diabases up to 80 m thick.

The overlying sandstone member, at least 250 m thick, has a complex structure: it contains red-colored and reddish-gray, arkosic and polymictic sandstones, siltstones, and argillites. The rocks of the member are characterized by cross-bedding, desiccation cracks, and wave ripple marks. In the coarse-grained greenish-gray sandstones of this member

on the left bank of the B. Kundat River, L. V. Alyabina discovered a psilophyte flora that makes it possible to determine the age of the red-bed sequence.

Stratigraphically above the sandstone member lie the tuff conglomerates of the Palatnino volcanic sequence. In the section along the Kundustuyul River the red-bed sequence has a total thickness of about 1400 m. Approximately 20% of its volume consists of diabase sills.

The conglomerates of the red-bed sequence on the Kundustuyul River are intensely epidotized, and within the area of distribution of the red-bed sequence in the divide of the B. and Mal. Kundustuyul we encountered large blocks of milky-white, finely banded zonal quartz, characteristic of quartz veins accompanying stocks of Late Devonian (?) alkaline granites along the eastern boundary of the graben.

In the basin of the Tuluiul River the red-bed sequence is folded into a synclinal fold of northeastern strike, cut diagonally near the mouth of the Maly Tuluiul by a thick zone of foliation (up to 0.5 km), within which the red-bed deposits are penetrated by a mass of thin veinlets of pole-shaped pink calcite. By the composition of the constituent rocks the sequence is clearly divided into three large members: a conglomerate-sandstone member (700 m), an argillite member (up to 600 m), and a sandstone member (more than 200 m), with the conglomerates of the lower member, as a rule, not being basal. In the upper member, along with fine- and medium-grained sandstones, there are conglomerate-like varieties. The sequence is cut by dikes of labrador porphyrites and rests unconformably on Cambrian greenstone porphyrites, having a total thickness of not less than 1500 meters.

In the section along the Kozhukh River, above the mouth of the Tiguli River, the red-bed sequence, through a basal conglomerate, rests on the eroded surface of the Kozhukh massif. The thickness of the conglomerate is no more than 20 m. Its composition is dominated by boulders and coarse pebbles of granitic rocks of the Kozhukh massif; pebbles of pinkish-gray and cherry-red albitophyres are present. Higher in the section, within the conglomerate-sandstone member (650 m), there is an alternation of red-bed and gray-bed sandstones, often cross-bedded, with horizons of argillites. Thin sills of diabases are encountered rarely. Stratigraphically higher, sandstones are almost completely displaced from the section by argillites, composing a member up to 500 meters thick. Above the argillites lies a member of coarse-clastic rocks with a thickness of not less than 500 meters. The member begins with sandstones; then coarse-pebble conglomerates appear in it (50 m), which, along with other components, contain pebbles of white oolitic limestones characteristic of the area of the village of Karacharovo (20 km to the northwest). The conglomerates are replaced by coarse-grained, cross-bedded red-bed sandstones with lenses of conglomerates. The sequence is cut by dikes of labrador porphyrites and diabases, and on the left bank of the Kozhukh River opposite the mouth of the Tiguli River it is unconformably overlain by diabase amygdalophyres. The total thickness of the sequence in the section along the Kozhukh River is 1700 m.

Thus, the red-bed sequence of the area in all the principal sections rests unconformably on Cambrian rocks or on the weathering crust of intrusive rocks of the Martaiga complex and is clearly subdivided into three large members: a lower coarse-clastic member, a middle fine-clastic member, and an upper coarse-clastic member. In the southern part of the area it is saturated with diabase sills and reaches a thickness of 1400 meters. The upper member of the sequence contains a flora of Koblenzian psilophytes. The red-bed sequence is overlain unconformably by volcanic rocks of the Palatnino Formation, which is directly observed on the Kozhukh River opposite the mouth of the Tiguli River and is also established by geological mapping.

in the Palatnaya graben, where the volcanogenic formations occur at different horizons of the red-bed sequence, differing in stratigraphic position by more than 1000 meters.

Palatnaya volcanogenic sequence

Under the name Palatnaya we describe a thick volcanogenic sequence that lies stratigraphically above the red-bed sequence and that attained its greatest development in the basin of the Palatnaya River. In volume it corresponds to the Palatnaya Formation of A. R. Ananyev [3]. The unconformable character of the occurrence of the sequence is indicated by its overlap onto different horizons of the red-bed sequence in the Palatnaya graben and directly onto Cambrian and Precambrian carbonate sequences in the basin of the Natalyevka River.

The volcanogenic sequence is represented most fully in the Palatnaya graben, where, according to the composition of its constituent rocks, it can be subdivided into two large members: a lower one—essentially tuffaceous—and an upper one—effusive. The lower member of the sequence is composed of tuff conglomerates and mixed lithovitroclastic tuffs of andesite porphyrites. The thickness of the member is not constant and decreases sharply from south to north and northeast, to complete wedging out. Thus, in the section south of the town of Palatnaya the thickness of the tuffaceous member reaches 1000 m; in the section along the B. Tuluul River it is reduced to 150 m, and in the basin of the Natalyevka River it practically disappears.

The upper member of the sequence is composed of effusives of basic and intermediate composition with horizons of tuffaceous rocks. Predominant in the composition of the member are andesite porphyrites; less widespread are plagioclase-hornblende, plagioclase-pyroxene, and pyroxene porphyrites, labrador porphyrites, albitophyres, and basalts. The poor exposure of the area prevents compilation of a complete section of the sequence. The volcanogenic sequence was studied by us in comparatively great detail in the area of the settlement of Makarak, along the valley of Vaskin Klyuch, where it has a complex structure with a regular increase in the thickness of individual rock members in a northeastern direction.

Among the rocks composing the sequence from bottom to top, diabasic porphyrites, plagioclase porphyrites, albitophyres, and melaphyre basalts are distinguished here.

A special position within the volcanogenic sequence is occupied by melaphyres, melaphyre basalts, and labrador porphyrites, which represent a single natural association. The listed rocks are distributed at the head of Vaskin Klyuch and on its watershed with the Kiya River, where they occur either on the labrador porphyrites of the Berikul Formation or on the above-described plagioclase porphyrites and albitophyres of the Devonian volcanogenic sequence. The paleobasalts of Mount Lokhmataya have an analogous stratigraphic position and are overlain by augite porphyrites. The latter are also widely developed in the area of the town of Palatnaya, in the upper parts of the volcanogenic sequence.

The effusive rocks noted above do not exhaust the entire diversity of rocks of the volcanogenic sequence, but they give an idea of its composition. It should only be noted that the labrador porphyrites within the sequence are not only associated with basalts, but also form independent large bodies in the lower part of the sequence in the basin of the M. Tuluul River, as well as sills and dikes in the red-bed deposits along the Sosnovka and Bodochat Rivers.

The thickness of the effusive member of the volcanogenic sequence in the basin of Vaskin Klyuch does not exceed 300 m; however, in the Palatnaya graben, according to sections taking account of structure, it reaches 1000 m. The total thick-

the thickness of the volcanogenic sequence in the Palatninskii graben reaches 2000 m.

In the basin of Vaskin Klyuch and along the Kiya River near the settlement of Makarak, the rocks of the volcanogenic sequence contain small stocks of titanaugite gabbros and gabbro-syenites and have undergone intense alkaline metasomatism. On the southern slope of Mt. Palatnaya, pyroxene porphyrites are cut by peculiar granite-porphyries with a micropegmatitic groundmass. The Palatninskaya sequence is tentatively dated to the Eifelian.

REFERENCES

1. L. V. Alabin. The Olginskii intrusive massif in the northwest of the Kuznetsk Alatau. Bulletin of the West Siberian and Novosibirsk Geological Administrations, issue 3, 1959.

2. L. V. Alabin. On the subdivision of the deposits of the Telbes Series in the north of the Kuznetsk Alatau. Materials on Mineralogy, Petrography, and Mineral Resources of Western Siberia and Krasnoyarsk Krai, issue 3, Tomsk State University Press, 1965.

3. A. R. Ananyev. The Kozhukhovskii granodiorite massif in the northwestern spurs of the Kuznetsk Alatau. Scientific Notes of Tomsk State University, No. 14, 1950.

4. A. R. Ananyev. On breaks in the deposits of the continental Devonian of the Sayano-Altai mountain region according to paleobotanical data. In: Proceedings of the Paleobotanical Conference. Tomsk State University Press, 1962.

5. N. N. Dingelshtedt. Geological investigations in the basin of the B. Kozhukh River. Transactions of the All-Union Geological Prospecting Association, issue 249, 1933.

6. Ya. G. Kats. Principal stages in the development of the central part of the Minusinsk intermontane trough in the Devonian. Proceedings of Higher Educational Institutions, Geology and Exploration, No. 12, 1959.

7. I. V. Luchitskii. Volcanism and tectonics of the Devonian depressions of the Minusinsk intermontane trough. Proceedings of the Academy of Sciences of the USSR, Moscow, 1960.

8. A. A. Mossakovskii. Tectonic development of the Minusinsk depressions and their mountain framing in the Precambrian and Paleozoic. Gosgeoltekhizdat, Moscow, 1963.

9. D. V. Nikitin. Geological structure and mineral resources of the northwestern part of the Kuznetsk Alatau. Transactions of TsNIGRI, issue 124, 1940.

10. A. N. Churakov. Kuznetsk Alatau. Its geological history and geochemical epochs. Essays on the Geology of Siberia. Publishing House of the Academy of Sciences of the USSR, Moscow, 1932.