MAIN FEATURES OF INTRUSIVE MAGMATISM IN THE UVOLGA–CHAPA INTERFLUVE AREA IN THE NORTHERN PART OF THE YENISEI RIDGE

A. D. Nozhkin

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

With the exception of the territories directly adjoining the gold-bearing districts, the northern part of the Yenisei Ridge has been very poorly studied geologically. Many important questions of stratigraphy, tectonics, and especially intrusive magmatism have still not been resolved; the metallogenic potential of the area has not been sufficiently clarified. In this connection, the publication in the literature of new information on the geology of particular specific areas of it should, in our opinion, be of definite interest.

During thematic investigations in 1960–1963 in the Uvolga–Chapa interfluve, and also partly to the north (the Vorogovka River) and to the south (the Teya River) of it, the author had the opportunity to collect extensive factual material on the intrusive formations of this territory. The processing of this material served as the basis for writing the present article.

The indicated area belongs to the northern axial part of the Yenisei Ridge, lying within the northeastern limb of the Tatar anticlinorium. The main structural element of the area described is the so-called Uvolga graben, extending in a northwestern direction from the valley of the Uvolga River to the Chapa River for a distance of about 60 km (Fig. 1). Along the margins of the graben there are developed mainly deeply metamorphosed formations of the Penchenga Formation of the Middle Proterozoic, which in individual cases are transgressively overlain by a metamorphic sequence of the Upper Proterozoic (the Gorbilok and Uderei formations). Directly in the structure of the graben participate weakly metamorphosed deposits of the Vendian complex, subdivided into three formations: the Lopatin, Chividin, and Nemchan formations [8]. Their assignment to the Precambrian [16] is confirmed, in particular, by the absolute age value of glauconite from the upper horizons of the Nemchan Formation, equal to 693 million years (author’s material, determinations by L. V. Firsov, 1964).

Intrusive rocks are distributed exclusively among the metamorphic sequences that border the graben. They have not previously been studied in detail here by anyone. In the reports of G. E. Nesmikh, E. V. Pokrovsky, V. I. Kazarov, Yu. A. Kudryavtsev, and other geologists who at various times headed geological surveying work, only a brief description is given of some granitoids, usually assigned to a single complex of Proterozoic age. In the published literature, mention of grani-

in the granitoids of the Uvolga River is available only in the work of O. A. Gliko [5], who, based on the research materials of G. E. Nesmikh and E. Ya. Yatsenko, gives a concise characterization of the Nogatino and Uvolga granites.

Fig. 1. Diagram of the spatial distribution of intrusive formations in the Uvolga–Chapa interfluve. Compiled by A. D. Nozhkin, 1963. Deposits of the upper structural stage: 1 — Nesmian suite, 2 — Chingidii suite, 3 — Lopatina suite, 4 — formations of the middle structural stage (Uderei and Gorbilok suites), 5 — metamorphic sequence of the lower structural stage (Penchenga suite), 6 — ultrabasic rocks of vein type, olivine pyroxenites, 7 — nepheline syenites (in suites), 8 — essexites, quartz syenites, syenite-porphyries, 9 — fine-grained granites, 10 — Nogatino granites, 11 — gneiss-granites; 12 — faults, 13 — geological boundaries, 14 — elements of the bedding of rock layering.

The author’s studies have established that, in addition to granites, alkaline and ultrabasic rocks are developed in the area. On the basis of general geological, petrographic, petrochemical, facies, geo-

Fig. 2. Diagram of chemical compositions of magmatic rocks 8413, 3–19, P-10 — gneiss-granites; P-9, P-13 — granodiorites (Uvolga River); Sk-B, 3–16 — Nogatinskie biotite granites; Sk-T, M-14 — Nogatinskie tourmaline granites; 8098 — fine-grained granite (Noiba River); 8083 — muscovite granite; 8025 — albitized granite; 8508 — porphyritic granite; 8509 — fine-grained granite (Uvolga River); 34–4 — quartz syenite; B-2 — syenite, 37–15 — syenite-porphyry; 8147 — nepheline syenite-porphyry; 8151 — zeolitized syenite-porphyry; 8144 — bekinite; 8201, K-50-1 — vein kimberlites; AH-6-1 — olivine pyroxenite.

Average rock types according to R. Daly: 2 — Precambrian granite of Sweden; 45 — granodiorite, 18 — syenite; 27 — keratophyre; 37 — foyite; 41 — phonolite; 128 — tinguaite.

Some rock types given special names (after A. N. Zavaritskii): 445 — apachite; 538a — vicoite; 576 — bekininite; 639 — olivine teschenite.

Kimberlite rocks of Siberia: 134-Б — vein kimberlite of the Chapa River [6]; 431-Б — vein kimberlite of the Chadobets uplift [14]; 177 — vein kimberlite of Yakutia [7]; 5 — kimberlite breccia of Yakutia [7].

chemical and other features, five independent intrusions, successive in time, are clearly distinguished: 1) the Uvolga gneiss-granite intrusion, 2) the Nogatin granite intrusion, 3) the Noiba intrusion of fine-grained granites, 4) the syenite intrusion, 5) the intrusion of alkaline–ultrabasic rocks of vein type. These intrusions correspond to a considerable degree to five quite definite magmatic complexes or specific magmatic formations [9].

Intrusion of gneiss-granites. The principal massifs of gneiss-granites lie west of the Uvolga graben and are situated in the axial part of the Tatarka anticlinorium, among marbles and crystalline schists of the Penchenga Formation. Their occurrence, as a rule, is concordant with the main structural elements of the metamorphic strata.

The most widespread rock type composing the intrusive bodies is gray biotite porphyritic gneiss-granite, which in individual cases is replaced by muscovite granites, and in the contact zone often passes into granodiorites. Within the massifs there are also vein-like bodies of pegmatites.

The usual composition of the gneiss-granites is as follows: potash feldspar (30–35%), plagioclase No. 12–15 (20–30%), quartz (30–35%), biotite (5–10%). In the composition of their accessories they belong to the zircon–apatite type. The structure of the rocks is indistinctly hypidiomorphic. The idiomorphism of plagioclase is often obscured by phenomena of its replacement by microcline. In individual areas the structure of the gneiss-granite assumes a granoblastic, poikiloblastic, micropegmatitic appearance.

Petrochemically these are rocks of the normal series, oversaturated with silica \((Q = 31–37.5)\), with a predominance of potassium oxide in the alkalis \((n < 50)\) (Table 1, Fig. 2).

The formation of the gneiss-granites evidently took place under conditions of the abyssal facies [10–18], as indicated by such features as the comparatively uniform composition of the rocks, due to the single-phase emplacement of the intrusion, their medium- and coarse-crystalline habit, the constant presence of fresh porphyroblastic segregations of microcline developing metasomatically, the absence of zoning in plagioclase, parallel-linear textures emphasized by feldspar and biotite plates, the presence of lens-shaped pegmatites, etc. This is evidenced to an even greater extent by the character of the contact zone: development of a wide (up to 0.5–1 km) field of quartz-mica, quartz-garnet–mica crystalline schists, as well as gneisses and migmatites.

The Uvolga gneiss-granites are the most ancient granitoids of the district. Since they occur only in rocks of the Penchenga Formation, one can speak with certainty only of the lower age limit of these rocks and, consequently, regard them as no older than the metamorphic strata of the Tei Series. Judging from descriptions available in the literature [3, 5, 11], porphyroblastic gneiss-granites are widely distributed in the Yenisei Ridge. They compose such massifs as the Posolnensky, Ryazanovsky, Garevsky, Uvolga, Tei, Chapa, and others. M. I. Volobuev et al. [2, 3] combine the gneiss-granites of the Angara region into the so-called Tei complex. Evidently, the Uvolga intrusion can be included in this complex, since it is located in the same linear zone of the axial part of the Tatarka anticlinorium, within which the Tei, Chapa, and other massifs are situated. The absolute age of the Tei massif is about 1000 million years [2, 3].

In its characteristics the Tei complex corresponds to the formational type of granitic batholiths. Indeed, large linearly elongat—

Table 1

Chemical composition of intrusive rocks (wt.%)

Chemical composition of intrusive rocks (wt.%)
Continuation of Table 1

Continuation of Table 1

Note. Chemical analyses were performed at the Tomsk Integrated Expedition. 8413—gneiss-granite porphyroid; 3—19—granite of rose-pink porphyritic facies; T1-10—gneiss-granite porphyroid; P-9—granodiorite, gray, biotitic; P1-13—granodiorite, pink; 3—11-6—granite, pink, fine-grained; M-14—granite, pink, biotite, fine–medium-grained; SK-7—granite, light crimson; 8098—granite, medium-grained, muscovite-microcline; 8083—granite, muscovite; 8025—granite, leucocratic, weakly albitized; 8508—granite porphyritic; 8509—granite, light-gray with elevated (up to 40%) quartz content; B-2—sienite; 37-15—sienite porphyry; 8147—nepheline–sienite porphyry; 8151—nepheline sienite porphyry; 8144—bekinkinite; 8201—alkaline kimberlite, Marsalovskogo settlement; K-50-1—limy kimberlite, Uvolga River; 134-B—limy kimberlite (Chapa); 431-B—limy kimberlite, Chapa deposit [14]; 5—kimberlite breccia, Yakutia [7]; 177—limy kimberlite, Yakutia [7]; ANG-6-1—olivine picroksenite.

Continuation of Table 1

in plan view, the massifs show a distinct connection with the principal trend of the folded structures of the region. Occurring within the Middle Proterozoic metamorphic sequence, the magmatic bodies bear clear signs of formations that arose in place of the enclosing rocks. Such signs can be seen, above all, in the contact zone of the massifs, where biotite gneiss-granites, toward the contact, are gradually replaced by granodiorite still more enriched in biotite, then by migmatites, biotite gneisses, and, finally, by biotite, quartz-biotite, and other crystalline schists. In essence, what is observed here is a preserved zonality of magmatic replacement, with a broad manifestation of metasomatic processes proper. An important indication of the nonintrusive character of the bodies is also the absence of basic and intermediate rocks of purely magmatic origin that might have been products of the intrusion of basic or intermediate magma.

M. I. Volobuev et al. [3] believe that the gneiss-granites of the northern part of the ridge formed during the early-folding stage of the Riphean geosynclinal stage. Yu. A. Kuznetsov [9] regards similar batholithic bodies as pre-Riphean syntectonic ones. In his opinion, it is precisely this, as well as the replacement not of sedimentary but of metamorphic sequences, that explains their distinctive character, expressed in a pronounced gneissic aspect and in the widespread development of feldspathized rocks in the contact zones.

It may be thought that the Uvolga gneiss-granites formed in pre-Sukhopit time, since in the basal horizons of the Sukhopit Series, in areas bordering these granites, numerous fragments of microcline are encountered, analogous to those of the porphyroblasts of the gneiss-granites.

It is not excluded that granitoids analogous to those described are widely distributed in folded regions and represent a distinctive gneiss-granite formational type.

No mineral deposits are known in connection with this intrusion in the region. Judging from the content of trace elements in the magmatic rocks, the initial magma was enriched in Zr, Ba, Sr, Mn, Ag, and, to a lesser extent, Mo, Sn, Be, Y.

Nogata granite intrusion. Granites of an entirely different type are developed on the Uvolga–Nogata watershed and are known as the Nogata granites. In the region, the Nogata intrusion forms one small massif (25 km²), isometric in plan. In the north, at the mouth of the Nogata, it cuts through and metamorphoses the gneiss-granites and in places borders, along tectonic dislocations, the sedimentary rocks of the Vendian complex. Most of it is emplaced in the metamorphic rocks of the Penchenga Formation.

The Nogata massif belongs to the type of discordant, post-tectonic intrusions with autonomous internal tectonics. Its contacts with the enclosing rocks are sharp.

The massif is dominated by red medium-grained biotite granites, consisting of K-feldspar (45–50%), albite-oligoclase No. 12–15 (20–22%), quartz (35–37%), and biotite (5%). Accessory minerals are represented by sphene, orthite, and magnetite. The rock texture is hypidiomorphic-granular, sometimes granophyric and typically granitic. In the contact part of the body, tourmaline granites enriched in fluorite and zircon are developed.

A petrochemical feature of the Nogata granites is their oversaturation with alumina and especially with silica ($Q = 35$–$40$),

low content of plagioclase lime (C—0.58–0.9) and predominance of potassium alkali in the composition ($n = 28$–40) (Table 1, Fig. 2).

The near-contact zone of the intrusion is represented by hornfelses, silicified rocks, and skarns of various composition. Among the latter, pyroxene and pyroxene-garnet varieties predominate; garnet-magnetite, vesuvianite, and pyroxene-epidote skarns are of subordinate importance.

The granites and skarns in several places are cut by a series of pegmatite veins, which are distinguished by a coarse-grained pegmatoid or, more rarely, graphic structure and consist of microcline, albite, quartz, tourmaline, and biotite.

In terms of size and conditions of occurrence, the massif should be assigned to the stock type. Its formation most likely took place in the normal-granite, medium-depth facies. This is indicated by the uniformity of the petrographic composition of the rocks, the weak development of porphyritic, fine-grained endocontact subfacies, the character of contact metamorphism, and the manifestation of the pegmatite phase.

The absolute age of the intrusion (from orthite, author’s material, determinations by M. I. Volobuev et al.) is $660 \pm 45$ million years. On this basis, in terms of age it is most correctly paralleled with the Ayakhta intrusion, whose absolute age, according to the same investigators, is $670 \pm 40$ million years [2, 3], and which also, incidentally, is orthite-bearing. Consequently, both the Nogata and the Ayakhta granites most likely belong to a single Ayakhta complex [3].

Yu. A. Kuznetsov [9], considering the Upper Proterozoic granites of the central part of the Yenisei Ridge, assigns them to the formational type of granite batholiths. The Nogata intrusive, in terms of occurrence conditions, does not differ fundamentally from other massifs. It should only be noted that in the erosional section in which the massif is now observed, it is evidently an intruded body, i.e., partially crystallized magma underwent some upward displacement.

On the basis of the presently available data on the absolute geochronology of magmatic formations of the Yenisei Ridge, it may be assumed that the Upper Proterozoic granites in this region have a very long history of formation; moreover, in different structural-facies zones they arose at different times. The area under study belongs to that structural-facies zone in which early and late, so to speak, phases of granitoid magmatism of the batholith type were manifested. The first of these (gneiss-granites) took place in the early folded stage of the Riphean geosynclinal stage proper, or was formed in pre-Riphean time; the second—the Nogata granites—in the late-orogenic stage of the orogenic stage.

The main phase of formation of granite batholiths (the Posolnaya-Angara complex, age $850 \pm 60$ million years [2, 3]) coincides with the early-orogenic stage of development of the Yenisei branch of the Baikalian geosyncline. A large part of the massifs of the Posolnaya-Angara complex is concentrated in neighboring southwestern regions, where granitoids of the Teiskii and Ayakhta complexes were not manifested at all or were weakly manifested.

In connection with the Nogata intrusion, magnetite mineralization and rare-metal mineralization in skarns are known. The granites are characterized by elevated contents, in comparison with clarke values for these rocks, of Ni, Co, Mn, Pb, Cu, Zn, As, Y, and Yb. An important geochemical

A feature of the granites and skarns is also their elevated tin content.

The Noiba intrusion of fine-grained granites is represented by a number of small bodies, occurring especially often in the basin of the Noiba River, and more rarely in the upper reaches of the Uvolga River. In the upper reaches of the Noiba River, 10 bodies of such granites are known; the area of the largest of them is 4.5 km², while most of the bodies have an area of no more than 1.5 km². In plan, the bodies are usually irregular, with sinuous outlines.

The intrusion is dominated by pinkish-gray fine-grained granites (oligoclase No. 14–15—30–35%, potash feldspar 25–30%, quartz 25–30%, biotite 5–7%), which, in terms of accessory minerals, belong to the sphene–zircon–ilmenite type. The rock texture is hypidiomorphic-granular, more often normal granitic. Among them are widespread light-gray albitized granites, composed of saccharoidal albite and subordinate quartz and finely scaly sericite, as well as muscovite granites. The latter do not form independent intrusive bodies, but usually appear in the apical parts of massifs composed of biotite granites. Muscovite granites often pass into greisenized granites and typical greisens.

A common petrochemical feature of the noted varieties of granites is their belonging to the normal series of rocks (after A. N. Zavaritsky), an elevated alkali content ($a = 14$–17) with predominance of sodium oxide ($n = 56.3$–76.9), and a low value of feldspathic lime ($C$—up to 1.5) (Table 1, Fig. 2).

The contact metamorphism caused by this intrusion is insignificant. The vein suite is represented by dikes of spessartites. By these and other features, it may be considered that formation of the granites took place under conditions of the hypabyssal facies, with a broad manifestation of high-temperature postmagmatic processes that essentially led to the formation of typical apogranites [1].

Among the granitoids these are the youngest formations. They cut through the Nogatino granites, metamorphose all Precambrian formations up to and including the conglomerates of the Lopatin suite [13], and, in turn, are cut by the Paleozoic syenites described below.

Judging from radiological studies, age analogues of these granites are unknown in the southern regions of the ridge. Data on the absolute age of granitoids in the northern part of the ridge are very limited.

In terms of conditions of occurrence, composition, and the manifestation of high-temperature alterations in the form of albitization, muscovitization, etc., the granites described closely resemble the dike formations at the mouth of the Sogren Creek (Angara River) [11], the granites of the Rudikovka and Klimovka rivers, and the granite-porphyries of the Bolshoi Pit River. Similar granites were observed by us in the upper reaches of the Vorogovka, Tyrada, Kutukasa, and N. Surnikha rivers (northwest of the area described).

On the whole, in our opinion, the complex of fine-grained granites, in all its features, corresponds to the formation type of subvolcanic granites of geanticlinal mobile zones. This is all the more probable since, in some areas, similar granites occur in close spatial association with acid effusives.

An important geochemical feature of the granites described is their elevated content of rare elements (Mo, Zr, Be, Li, Nb, etc.).

The syenite intrusion is developed along the eastern margin of the Uvolga graben. It is dominated by syenites, quartz syenites, and alkaline syenite-porphyries, which make up a number of small intru-

sive bodies represented by dikes and stocks. The syenites consist of potassic feldspar (85–90%), biotite or hornblende (up to 5%), and albite (5–10%). Quartz is present in the quartz syenites in amounts up to 5–10%, and in the syenite-porphyries barkevikite, up to 3%, has been noted. Accessory minerals are represented by aeschynite, sphene, fluorite, and, more rarely, zircon and apatite. The syenites and quartz syenites have a hypidiomorphic-granular texture. Alkaline syenite-porphyries are characterized by a trachytoid texture of the groundmass, approaching a bostonitic one.

In petrochemical terms these are rocks of the plumasitic series \((a' = 7.6–39.2)\), weakly oversaturated with silica \((Q = 3–14)\), with a predominance of potassium in the alkali composition \((n = 35–41)\).

Contact changes in the country rocks are manifested only in weak recrystallization within a zone 5–10 m wide. Much more intensely expressed are processes of alkaline metasomatism, manifested in potassic feldspathization and albitization of both the intrusive bodies and the country rocks, as well as in the development of postmagmatic formations of various compositions.

Judging from the small size of the bodies, which have the form of stocks and dikes, the fine-grained, sometimes porphyritic appearance of the rocks, and their weak contact effect on the country rocks, it may be concluded that the syenites formed under conditions of the hypabyssal or even near-surface facies.

Recently subalkaline granites, syenites, and alkaline syenites have been identified in the basin of the Vorogovka River, in the upper reaches of the Kutukas and Isakovka rivers, on the N. Surnikha, and in other places. In general, they form a rather extended zone of northwestern strike, coinciding with a long-lived deep fault.

The absolute age of the syenite intrusion (from thorite and aeschynite, author’s material), according to determinations by R. M. Gold and others (Tomsk Polytechnic Institute), is \(470 \pm 15\) million years, and according to the data of studies by M. I. Volobuev and others (Moscow University), \(555 \pm 25\) million years. Consequently, in both cases the absolute-age figures make it possible to regard the syenite intrusion as Lower Paleozoic. The pegmatites of the alkaline syenites of the Middle Tatarka massif have an approximately analogous age (530–570 million years) [2, 3].

Thus, the formation of the syenite complex is connected with Lower Paleozoic tectono-magmatic activation, which most likely occurred at the boundary between the Middle and Upper Cambrian.

In the author’s opinion, the syenites should most properly be assigned to the alkaline granitoid formation in the sense in which this is shown in the work of Yu. M. Sheinman and others [19]. The grounds for this are: a) the spatial association of the syenites with Upper Proterozoic granitoids; b) the insignificant time break between the processes of formation of the alkaline complex and the latest among the granitoids, the complex of subvolcanic granites; c) the geochemical specialization characteristic of alkaline rocks of the granite series in this complex (Ba, Sr, Mo, Pb, Nb, etc.).

In the basin of the Noiba River, nepheline rocks (14) have been found, represented by nepheline syenite-porphyries, zeolitized pyroxene syenite-porphyries, and bekininkinites (Table 1, Fig. 2), which differ sharply from the subalkaline and alkaline granitoids. In a number of features they approach the alkaline basaltoids developed in the basins of the Chingason and Almanakan rivers, whose age position and formational affiliation are not yet entirely clear and will subsequently be considered by us separately.

Intrusion of alkaline–ultrabasic rocks of vein type. On the basis of composition, petrochemical, and other features, two rock types are distinguished: vein micaceous kimberlites and olivine pyroxenites.

Vein kimberlites were established by the author in the southeastern part of the Uvolga graben among the red-colored conglomerates of the Lopatin Formation. All the veins are oriented in a northwestern (310–330°) direction and dip at an angle of 40–50° to the northeast. Their thickness is 0.3–0.4 m. The contacts of the veins with the enclosing rocks are very sharp. Their contact effect on the enclosing rocks is very slight. Usually only weak bleaching of the red-colored conglomerates is observed in a zone 0.5–1.5 cm thick.

The kimberlite of the intrusive veins is a dense rock of bluish-gray color, with a massive or brecciated texture and a fine-porphyritic structure.

Under microscopic study, the strong alteration of the rock is conspicuous. In the porphyritic segregations, which make up no less than 25% of its total volume, and in the fragments, pseudomorphs of carbonate, serpentine, and chalcedony after olivine are visible. The groundmass consists of a fine-crystalline aggregate of carbonate and serpentine with numerous prismatic segregations of altered pyroxene and plates of phlogopite. The accessory minerals are represented by apatite, ilmenite, magnetite, and isolated grains of chromite.

The chemical composition and petrochemical properties of the rocks described are close to those of the vein kimberlites of the Chapa River, the Chadobets uplift, and the kimberlite breccias of Yakutia [6, 7, 15].

Farther north, on the Chapa River (the Glubokii, Almanakan, and Chingasan streams), similar vein formations occur in close spatial association with typical explosion pipes.

Together with the vein bodies of kimberlites, on the left bank of the Marasalovsky ditch two unaltered dikes of ultrabasic composition were exposed, previously described in detail by us together with F. P. Krendelev [8]. In composition these dikes correspond to the vein facies of olivine pyroxenites. The presence of titanium-bearing augite and especially phlogopite permits them to be assigned to the ultrabasic rocks of the alkaline series. This is also indicated by their petrochemical properties (Table 1), which are very close to those of teschenite (Fig. 2).

Kimberlites and olivine pyroxenites of the Uvolga River basin cut through deposits of the Vendian complex. In the Chapa River area, kimberlite pipes cut carbonate deposits of the Lower Cambrian. Consequently, on this basis alone they cannot be considered Proterozoic. In our opinion, it is most correct to regard the intrusion of alkaline–ultrabasic rocks as coeval with analogous formations of the Siberian Platform.

The formational type of the altered vein formations can evidently be characterized as kimberlitic. The olivine pyroxenites most likely represent late differentiates of the trap formation [17].

Thus, the material presented testifies to a fairly complex history of the intrusive formations of the area studied, confined to a zone of a long-lived deep fault that underwent repeated tectonic activation. At the same time, the activation was manifested most intensively in the Late Paleozoic and Mesozoic epochs.

References

1. Beus A. A., Severov Z. A., Sitkin L. A., Subbotin K. D. — Albitized and greisenized granites (apogranites), Publishing House of the Academy of Sciences of the USSR, 1962.

2. Volobuev M. I., Zykov S. I., Musatov D. I., Stupnikova N. I. — Magmatic formations of the Yenisei Ridge. Materials on the Geology and Mineral Resources of Krasnoyarsk Krai, issue 3, 1962.

3. Volobuev M. I., Zatsepin E. F., Zykov S. I., Stupnikova N. I. — Magmatic formations and magmatic complexes of the Yenisei Ridge, Problems of the Geology of Krasnoyarsk Krai. Moscow State University Press, 1964.

4. Geology of the USSR, vol. 15. Krasnoyarsk Krai, part 1, 1961. Stratigraphy and magmatism of the Yenisei Ridge.

5. Gliko O. A. Geological structure and metallogenic zoning of the Yenisei Ridge. Soviet Geology, collection 62, 1957.

6. Karpinsky R. B. On the discovery of vein kimberlites in the Yenisei Ridge. Materials on the Geology of Mineral Resources of Krasnoyarsk Krai, issue 3, 1962.

7. Kovalsky V. V. — Kimberlite rocks of Yakutia. Publishing House of the Academy of Sciences of the USSR, vol. 130, no. 2, 1960.

8. Krendelev F. P., Nozhkin A. D. — On post-Cambrian magmatism in the Yenisei Ridge. Geology and Geophysics, no. 9, 1961.

9. Kuznetsov Yu. A. — Main types of magmatic formations. Nedra Publishing House, 1964.

10. Kuznetsov Yu. A. — Facies of magmatic rocks. Problems of the Geology of Asia. Publishing House of the Academy of Sciences of the USSR, vol. 2, 1955.

11. Kuznetsov Yu. A. — Petrology of the Precambrian of the South Yenisei Ridge. Materials on the Geology of Western Siberia, no. 15, Tomsk, 1941.

12. Moore G. G. — Differentiated alkaline intrusions of the northern margin of the Siberian Platform. Publishing House of the Academy of Sciences of the USSR, geological series no. 8, 1957.

13. Nozhkin A. D. — Phenomena of contact metamorphism of the basal red-colored formation in the northern part of the Yenisei Ridge. Materials on the Geology and Mineral Resources of Western Siberia, Tomsk, 1964.

14. Nozhkin A. D., Cherepnin V. K. — The first discovery of nepheline rocks in the north of the Yenisei Ridge. Geology and Geophysics, no. 11, 1966.

15. Polunina L. A. — New data on the ultrabasic rocks of the Chadobets uplift. Information Collection of VSEGEI, no. 40, 1960.

16. Resolution of the conference on the stratigraphy of Upper Precambrian deposits of Siberia and the Far East, Novosibirsk, 1962.

17. Sobolev V. S. — Petrology of the traps of the Siberian Platform. Proceedings of the Arctic Institute, vol. 43, 1936.

18. Usov M. A. — Facies and phases of intrusives. In a collection dedicated to the memory of Academician Usov. Publishing House of the Academy of Sciences of the USSR, 1960.

19. Sheinman Yu. M., Apeltsin F. R., Nechaeva E. A. — Alkaline intrusions, their distribution and mineralization associated with them. Geology of Deposits of Rare Elements, issue 12–13, 1961.