MAIN FEATURES OF THE GEOLOGY AND PETROGRAPHY OF THE LEBEDEV PLUTON (GORNY ALTAI)

V. I. Yarygin

(Presented by the scientific seminar of the Department of Petrography)

The intrusive massifs of the junction of Gornaya Shoria and Gorny Altai have long and repeatedly attracted researchers in connection with the gold-bearing character of the region.

The first study of the rocks of the Lebedev pluton is found in the work of A. M. Kuzmin [8] on the geology of the upper part of the basin of the Lebed River. In this work considerable attention is devoted to describing the principal varieties of intrusive and host rocks and to substantiating the age of the pluton, which A. M. Kuzmin considered Cambro-Silurian. Later, in 1936, A. P. Lebedev [10] carried out route observations along the valleys of the Lebed and Kaurchak rivers for the purpose of studying the magmatism of the region. Still later, in 1939, V. A. Kuznetsov and G. P. Nagorskii worked in the region. Recently V. A. Kuznetsov et al. [6] combined all the granitoid massifs into the Lebedev gabbro-plagiogranite complex and substantiated its place in the scheme of the polycyclic development of magmatism in Gorny Altai. In 1950–1958, in the area of distribution of the Lebedev pluton, geologists of the WSTGU E. S. Shinkarev, V. I. Fominskii, V. M. Sennikov, and V. P. Studenikin carried out geological mapping at various scales. All of them note the complex composition of the Lebedev pluton, the formation of which took place in the Middle and Upper Cambrian. In 1964 a work by N. N. Amshinskii et al. [1] on the accessories of Gorny Altai was published, in which much space is devoted to the geochemical features of the rocks of the Lebedev pluton.

The Lebedev pluton, at the present erosion level, is mapped as three independent massifs. The Sadrinskii massif (Lebedskoi according to Amshinskii) is exposed in the basins of the Baigola, Toguny, and Bazly rivers and, respectively, in the lower and middle courses of the Sadra and Lebed rivers. The Lebedev massif is located east of the Sadrinskii, within the upper courses of the Sadra and Lebed rivers. Each massif occupies an area of 280–250 km². In the north, in the area of the B. Magalak River, the smallest (20 km²) isometric Magalak massif is found. The massifs are separated by narrow belts of host rocks; therefore it is quite probable that, joining at depth, they form an enormous batholith-like body. The author of this article has carried out a study of the petrography of the pluton (especially, in detail, the Lebedev massif) in the very recent period. This article is devoted to the results of that study.

The total length of the Lebedev pluton is 70 km; its width varies from 3 to 20 km, which amounts on average to 500 km² in area.

It is located in the southern part of the Kondoma–Lebed mobile zone, which is a transitional belt between the southwestern depression of the Shoria anticlinorium and the northeastern limb of the Uymen–Lebed synclinorium. The Kondoma–Lebed mobile zone is composed predominantly of Cambrian effusive and effusive-sedimentary deposits (Fig. 1). In the lower part of the section occur deposits of the Manzherok \(Cm_1\) (Kondoma)*) suite, represented by hornblende and anthophyllite amphibolites, diabases and their tuffs, and quartzites. In the form of small areas in the interfluve of the Baigol and Sadra rivers, carbonaceous-clayey schists, sandstones, and gravelites of the Kayancha \(Cm_1\) (Usa) suite are exposed. In the north of the Kondoma–Lebed zone, diabases, pyroxene porphyrites, and green tuffites of the Lower Kaim \(Cm_2\) (Kourin) suite are developed. Basal conglomerates, tuffaceous sandstones, chlorite and amphibole schists of the Upper Kaim \(Cm_2\) (Mundybas) suite lie transgressively upon it. In the Kyrgyz graben occur dolomitic limestones, siltstones, and sandstones of entirely conditionally Upper Cambrian age. Terrigenous Devonian formations, exposed in the Andoba graben, overlie the Cambrian effusive-sedimentary deposits.

The junction of the Kondoma–Lebed zone with the Shoria anticlinorium and the Uymen–Lebed synclinorium takes place along a series of regional faults. In the east it is separated by two submeridional Kondoma–Lebed and North Abakan faults with steep dips. They extend from Lake Sadra in the south to the Lebed River, then bend around the Shoria anticlinorium from the northwest and southeast, respectively. The rocks between these faults are intensely schistose and transformed into amphibolites. Apparently, this belt of rocks is the southern continuation of the Tashelga–Kondoma zone of folding. West of the Kondoma–Lebed fault passes the Sadra cataclasis zone, extending from the Baigol River to the headwaters of the B. Magalak River. It is a thick belt of crushed rocks with a series of local small-amplitude displacements. In the north the zone grades into a fault of the normal-fault type, producing the rectilinear contact of the Magalak massif. In the area of Lake Sadra, typical orthogneisses are formed within it. The intrusive rocks enclosed between the Sadra and Kondoma–Lebed faults are intensely cataclased and gneissified. The Kondoma–Lebed mobile zone is joined to the Uymen–Lebed synclinorium by means of the Kainin–Kourin fault. The Lebed pluton is structurally fitted within the Kondoma–Lebed mobile zone. In plan it is a linearly elongated body of batholithic type, stretched in the meridional direction. The eastern contact has a comparatively rectilinear form independent of the forms of the relief, owing to its steep dip. The northern boundaries are characterized by broad aureoles of contact-metasomatic formations, the cause of which is probably the gentle dip of the contact in this place. In the west the pluton is steeply (70–80°) overlain by deposits of the Lower Ordovician. The age limits of the Lebed pluton are established within narrow bounds—from the Middle Cambrian to the Lower Ordovician. The lower boundary is determined by the intrusion of granites into Middle Cambrian deposits on the northern and eastern contacts; the upper, by the foundation of the transgressive overlap of the Sadra massif by deposits of the Lower Ordovician in the area of the settlement of Suranash and the Bazly River. Taking into account the reliability of the observations listed, the commission for determining

*) In parentheses are given the names of suites according to the stratigraphic scheme of Gornaya Shoria.

of absolute age assigns the Lebed pluton to massifs dated with sufficient accuracy by the biostratigraphic method [2].

Fig. 1. Schematic geological map of the Lebed pluton: 1—red-colored sandstones, siltstones, D; 2—greenish-gray variegated polymictic sandstones, shales, O\(_{1-2}\); 3—limestones, variegated siltstones, sandstones, Cm\(_2\); 4—pyroxene and plagioclase porphyries, tuffs, breccias, Cm\(_2\); 4)—pyroxene and plagioclase porphyries, tuffs, breccias, Cm\(_2\); 5—sandstones, shales, gravelites, Cm\(_1\); 6—diabases, amphibolites, Cm\(_1\); 7—plagiogranites, trondhjemites, Cm\(_{2-3}\); 8—quartz monzonites, granodiorites, tonalites, Cm\(_{2-3}\); 9—various plagiogranites, Cm\(_{2-3}\); 10—pyroxenites, gabbro, diorites, and quartz diorites, Cm\(_{1-2}\). Massifs: (1)—Lebed, (2)—Sadrin, (3)—Atalyk.

Various rocks take part in the structure of the Lebed pluton; among them two separate groups are distinguished. Rocks of basic composition form a number of independent bodies at the mouth and headwaters of

of the Yaman-Sadry River, in the lower reaches of the Sadry River, in the area of the village of Suranash, and also occur as xenolithic remnants in the middle reaches of the Sadry River and the headwaters of the Baigol River. They form elongate, more rarely isometric in plan, weakly dissected bodies, which are localized in the marginal and exocontact parts of the massifs. The second group includes granitoids of varying composition.

A rather broad range of rocks takes part in the structure of the gabbroid bodies, the principal ones being pyroxenites, gabbro, hornblende gabbro, and gabbro-diorites. The remaining varieties (hornblendites, monzonites, gabbro-norites) are of sharply subordinate importance. All varieties are connected with one another by gradual transitions and are classified according to quantitative-mineralogical ratios of the rock-forming minerals (Table 1) and microscopic structural features.

Table 1

Quantitative-mineralogical composition of the gabbroids of the Lebedev pluton (vol. %)

Pyroxenites (diallagites, websterites). These rocks, in the form of spots and lenses, have been encountered in the central part of the bodies of the Yaman-Sadry River and the village of Suranash. In appearance they are black rocks with a greenish tint. Under the microscope it is seen that they consist of subidiomorphic grains of pyroxene of prismatic and tabular habit. Narrow interstices are filled by xenomorphic plagioclase. Monoclinic pyroxene forms homoaxial intergrowths with green hornblende. Replacement sometimes proceeds along cleavage and parting and forms lens-shaped inclusions. Cleavage on the prism (110) is clearly visible, but is sometimes obscured by coarse diallage parting on (100). In optical properties—\(Ng = 1.705 \pm 0.003\); \(Np = 1.688 \pm 0.003\); \(2V = +48^\circ\); \(CNg = 48^\circ\)—it corresponds to augite (\(Wo = 40,\ En = 48,\ Fs = 12\)) [3, 5, 12]. Olivine of the websterites (\(Ng = 1.730 \pm 0.005;\ Np = 1.694 \pm 0.003;\ 2V = -80^\circ;\ Fa = 30\%;\ Fo = 70\%\)) occurs only in relics inside loops of jenkinsite (\(Nm = 1.572 \pm 0.002\)) [12]. Amphibole (\(Nm = 1.670 \pm 0.002\)), pleochroism

Ng—dirty green, Np—light green, CNg = 18°, 2V = −74°) corresponds to ordinary hornblende with a 40% content of the iron molecule [11]. The hornblende is replaced by pistacite (2V = +75°; Ng—Np = 0.032). Plagioclase is replaced by epidote, zoisite, scapolite, and pyrophyllite. The ore mineral is confined to the reaction zones of replacement of pyroxene—hornblende and forms an aggregate of fine dust. Sphene is observed in large quantities (up to 1%) in the form of interstitial grains.

Within the gabbroid bodies, in zones of intense deformation, gabbros and pyroxenites underwent pervasive amphibolitization, turning into giant-grained hornblendites. They have been encountered in the form of bands and schlieren-like bodies at the mouth of the Yaman-Sadra River and near the settlement of Suranash. Macroscopically, these are dense, often giant-crystalline rocks of black color. Under the microscope, their structure is characterized by the exclusive idiomorphism of hornblende over saussuritized plagioclase. The hornblende is a pseudomorph after augite and, in optical properties, is identical to the hornblende of the pyroxenites described above. Among the accessory minerals present are sphene, apatite, and magnetite.

The rocks of the typical gabbroids make up 80–90% of the entire mass of the gabbroid bodies and are represented by normal gabbros, gabbro-norites, and hornblende gabbros. The marginal facies are represented by fine-grained varieties, and the central facies by medium-grained ones. All varieties are connected with one another by gradual transitions. The closeness of the material composition and the genetic relationship of this group of rocks allow us to give a combined description for them. Macroscopically, their coloration is grayish black; the texture is uniformly granular and massive. Schlieren are sometimes observed—accumulations of small grains of mafic minerals. The microstructure of the rocks is gabbroic and prismatic-granular. The primary structure is often complicated by corrosion phenomena of replacement and by cataclastic deformations of the primary minerals. Plagioclase is characterized by sharp idiomorphism and a high degree of de-anorthitization. In some samples, fresh grains of labradorite composition No. 50–65 are observed. Pyroxenes are often (as in pyroxenites) replaced by secondary minerals. Augite (Ng = 1.703 ± 0.002, Np = 1.683 ± 0.002, 2V = +55°, CNg = 40°, Wo = 41%, En = 48%, Fs = 11%) [3] is replaced by a homaxial compact pseudomorph of hornblende (Ng = 1.672–77 ± 0.002, Np = 1.659–63 ± 0.002, 2V = −66–70°, CNg = 16–18°, 40–45% of the iron molecule) [11]. After the hypersthene (Ng = 1.710 ± 0.002, Np = 1.697 ± 0.002, 2V = −50) of the gabbro-norite, complete pseudomorphs of bastite are formed (Nm = 1.584 ± 0.002, Ng—Np = 0.004). Newly formed lath-shaped grains of hornblende are grouped into continuous chain aggregates. It often contains poikilitic inclusions of plagioclase penetrating to 1/4 of the grain thickness. Compact hornblende is replaced by fringed grains of actinolite. In some gabbros, “shadow” relics of olivine are encountered. Secondary minerals are represented by zoisite, epidote, chlorite, and prenite (Np = 1.629 ± 0.002, 2V = +64, CNp = 0). Accessory minerals are represented by sphene, leucoxene, magnetite (up to 8%), and short-columnar apatite.

In direct contact with granitoids, the gabbroid rocks are transformed into hybrid monzonites, gabbro-diorites, and diorites. The transformation is expressed in the resorptive development of lattice microcline (2V = −80°, ∠Nm : ⊥(001) = 10°), de-anorthitization and acidification of plagioclase to An20–28 in diorite and An40 in gabbro-diorite. Hornblende along the periphery of crystals is “alkalinized.”

Quartz behaves aggressively, corroding plagioclase and hornblende. Biotite gradually replaces amphibole and forms patchy grains. Actinolite ($Ng = 1.639 \pm 0.003$, $Np = 1.623 \pm 0.003$, $CNg = 15^\circ$, 15% of the tschermakite molecule [11]) and patchy scaly muscovite ($Ng = 1.590 \pm 0.002$, $Np = 1.557 \pm 0.002$, 2–3% of the ferrimuscovite molecule [12]) are autometasomatic minerals replacing compact hornblende and plagioclase. Sphene is leucoxenized. Apatite has a fresh appearance.

Granitoids, which in areal extent exceed the early gabbroids many times over, are single-phase formations and are connected with one another by gradual transitions. The varieties of granitoids were determined on the basis of the classification of B. M. Kupletskii [9], substantially supplemented by V. E. Gendler [4]. In the southern part of the pluton, plagiogranites, trondhjemites, and tonalites were distinguished, which earlier investigators (E. S. Shinkarev, V. I. Fominskii) described under the name “granite.” In the north the pluton is composed of granodiorites and quartz monzonites. Quartz diorites and granites are rare rock types. The quantitative-mineralogical composition of these rocks is given in Table 2.

Table 2

Quantitative-mineralogical composition of granitoids (vol. %)

Plagiogranites are widespread in the south of the pluton and in stocks cutting the gabbro-peridotites of the B. and M. Atalyk rivers. In outward appearance these are leucocratic coarse-grained rocks. A large part of them has clearly expressed signs of gneissic structure. Under the microscope, short-prismatic crystals of plagioclase reveal elements of cataclasis and plicative dislocations, with the formation of wavy twin lamellae. The structure of the crystals is multizonal (up to 20 or more zones). The basicity of the core reaches $An_{37–40}$, and of the rims, $An_{7–10}$. Zoning is rhythmic. The marginal rims have an almost imperceptible for

shows normal zoning. Myrmekites develop in plagioclase at the boundary with microcline. Quartz is represented by two generations, differing in grain size and time of separation. Hornblende (\(Ng = 1.667 \pm 0.003\), \(Np = 1.644 \pm 0.002\), \(2V = -75^\circ\), \(CNg = 15^\circ\), 35% iron content [11]) forms tabular, short-prismatic grains, on which biotite often develops. Biotite is aggressively replaced by Mg-prochlorite (\(Nm = 1.601 \pm 0.002\), \(Ng = 1.606 \pm 0.002\), \(2V = 10^\circ\) [12]) and by spindle-shaped grains of pistacite (\(2V = -66\text{–}68^\circ\), \(Nm = 1.740 \pm 0.005\), \(Ng = 1.754 \pm 0.005\)). In episodic cases, cross-hatched maximum microcline is present (\(2V = -80\text{–}85^\circ\)). Accessory minerals are very rare and are represented by magnetite, apatite, zircon, and rutile (sagenite).

The western part of the Lebedev massif is occupied by a more alkaline variety of plagiogranites, which corresponds to trondhjemite [9]. Its distinctive feature, in comparison with plagiogranite, is an increased content of microcline and mafic minerals (by a factor of 2), and a weak degree of gneissosity. In addition, plagioclase reveals two generations, which are visually recorded very clearly. Plagioclase of the later (second) generation forms a fine-grained aggregate in the interstices of large crystals of the first generation. The potassium feldspar corresponds to maximum microcline (\(Ng = 1.527 \pm 0.002\), \(Np = 1.520 \pm 0.002\), \(\angle \perp (010) : Ng = 12.5^\circ\), \(2V = -72\text{–}79^\circ\) from 11 determinations and Monich’s diagram). Biotite (\(Np = 1.588 \pm 0.002\), \(Nm = 1.634 \pm 0.002\), \(Ng = 1.637 \pm 0.003\)—meroxene–lepidomelane with 43% iron content [11]) forms tabular flakes. Among accessory minerals, orthite appears.

In close association with the plagiogranites and trondhjemites are tonalites, which are characterized by a high content of mafic minerals, increased basicity of plagioclase (No. 50), and the presence of relict grains of augite and hypersthene inside “pod-scheelite” hornblende. Quartz forms large mosaic grains that aggressively resorb plagioclase and hornblende.

The northern part of the pluton is composed of granodiorites, quartz monzonites, quartz diorites, and granites, which differ in the quantitative ratios of the principal rock-forming minerals and partly in structural features (Table 2). Granodiorites and quartz monzonites are characterized by a high content of cryptoperthitic microcline (\(2V = -82^\circ\), \(\angle Nm : \perp (001) = 1\text{–}2^\circ\), \(Np = 1.517 \pm 0.001\), \(Ng = 1.527 \pm 0.001\)) and a monzonitic structure. Plagioclase crystals reveal a rhythmic, multizonal structure (\(An_{25\text{–}27\text{–}7}\)). They are aggressively resorbed by microcline, sometimes to the point of complete assimilation. The indicators of the latter are numerous “shadow” relict structures. Hornblende (\(Ng\)—dark bluish-green, \(Np\)—yellowish-green, \(CNg = 13^\circ\), \(2V = -80^\circ\), \(Np = 1.649 \pm 0.002\), \(Nm = 1.663 \pm 0.002\), \(Ng = 1.672 \pm 0.002\), 39% iron content [11]) forms tabular crystals growing in the interstices of other minerals. Biotite, pennine, and muscovite are secondary minerals. Accessory minerals are represented mainly by sphene, apatite, and magnetite, more rarely by zircon. Quartz diorites are hybrid rocks and occur at the endocontact of granitoids with basic rocks. Outwardly, these are medium-grained rocks of taxitic appearance. The microstructure is characterized by blastic growth of hornblende (\(Np = 1.649 \pm 0.002\), \(CNg = 16^\circ\), \(2V = -78^\circ\)) and quartz. Plagioclase is completely saussuritized. Granites are very rare and differ from granodiorites in their increased content of microcline and of the albite molecule in the composition of plagioclase (\(An_{20-15}\)). In the Sadrinsky massif, in the area of the settlement of Suranash, alkaline gra-

ites. Their mineralogical composition is as follows: plagioclase ($\mathrm{An}_{7}—\mathrm{An}_{42}$), quartz—23%, grid microcline—15%, mafic minerals (aegirine-augite: $N_p = 1.726 \pm 0.003$, $N_g = 1.741 \pm 0.005$, $CNg = 10^\circ$, $2V = +72^\circ$; eckermannite (arfvedsonite): $N_m = 1.635 \pm 0.002$, $N_g = 1.632 \pm 0.002$, $CNg = 36^\circ$, $2V = -70^\circ$), accessories (sphene, apatite)—1.5%.

The dike complex of the Lebedev pluton is very poor. By degree of genetic relationship, two groups of dikes are distinguished. The first group includes plagioaplites, aplites, microgranites, and micropegmatites. They have linear, vein-like forms. Their thickness varies from meters in swellings to several centimeters in constrictions. Their contacts are sharp. Plagioaplites and aplites are located in the exocontact, while microgranites and micropegmatites tend toward the marginal parts of the massifs. Dikes of the second stage predominate over dikes of the first group and are characterized by a certain diversity. In relation to the dikes of the first stage they are younger, since in the area of the Mayskoye deposit a vein of aplites is observed to be cut by a dike of plagioclase porphyrites. The dikes of this group are distributed unevenly, predominating in the northern part of the pluton. They have a persistent submeridional strike, sharp, steep contacts with chilled zones. In the dikes, quartz diabases, microgabbro, spessartites, and odinites predominate; diabases and pyroxene-plagioclase porphyrites are encountered more rarely. Quartz in the dikes is found as ichthyoglyphic intergrowths in the groundmass. The plagioclase of phenocrysts corresponds to labradorite No. 54, and that of microlites to andesine-labradorite No. 42. Augite ($CNg = 44^\circ$, $2V = +68^\circ$, $N_g = 1.695 \pm 0.002$) and hornblende ($CNg = 20^\circ$, $2V = -82^\circ$, $N_g = 1.654 \pm 0.003$) crystallize in the interstices of plagioclase, except in microgabbro and rocks of the lamprophyre series (odinite, spessartite), where they are idiomorphic. Primary contact hornblende in the lamprophyres is replaced by velvety rims of “alkalinized” blue-green hornblende ($N_p = 1.651 \pm 0.002$).

Contact metamorphism was manifested intensely at the contact with the granodiorites and quartz monzonites of the northern part of the pluton. Effusive formations in the exocontact zones were transformed into plagioclase-pyroxene and plagioclase-amphibole hornfelses. In the interfluve of the Lebed and Kaurchak, along the eastern boundary of the submeridional tongue of the Lebedev massif, there is a thick belt (200–300 m) of pyroxene-garnet-magnetite skarns, and skarns of similar composition, formed at the expense of limestone lenses enclosed in the effusives. Their pyroxene belongs to salite ($CNg = 40—42^\circ$, $2V = +56^\circ$, $N_g = 1.713 \pm 0.003$, $N_m = 1.693 \pm 0.002$), and the garnet ($n = 1.824 \pm 0.004$) to an isomorphic mixture of grossular (37%) and andradite (63%). Zones of variegated “confluent” pyroxene-garnet skarns are located in the area of the Burnyi Spring and the Albas River. The latter skarns are the product of replacement of effusives.

Thus, proceeding from the geology and petrography of the Lebedev pluton, one can determine the formational type of the pluton. For this it is necessary to give a brief characterization of the relationships between the granitoids and the bodies of gabbro.

The basic rocks considerably preceded the granitoids, since there are cutting contacts between them and the apophyses of plagiogranites, despite the generally gradual character of the transitions, caused by vigorous contact hybridism. At present the bodies of gabbroids represent a series of xenolithic remnants among the plagiogranites. Their primary minerals are strongly deanorthitized by processes of cataclasis and magmatic replacement. Despite the intense

replacement, nevertheless a weakly stratified structure of the bodies is still detected, and an analogy is observed in composition (wehrlites, koswites, and diallagites) with the gabbro-peridotites of Mt. B. and M. Atalyk. From what has been said, it may be concluded that these gabbroid bodies are probably independent intrusions and, judging by their composition and structural features, belong to the gabbro-pyroxenite-dunite complex of Mt. B. and M. Atalyk.

As for the granitoid massifs of the pluton, by the nature of their structural position and composition they belong to the plagiogranite complex of the epigeosynclinal type, according to the classification of Yu. A. Kuznetsov [7]. This is indicated by the form of their occurrence as complex fissure bodies and by their comparatively uniform and constant material composition with a siliceous-sodic specialization. Rocks of intermediate composition (diorites, quartz diorites, and gabbro-diorites), judging by the features of their structure, texture, and composition, correspond to hybrid formations, while the suite of dike rocks is poor and is represented mainly by aschistic rocks. These last two facts are also inherent properties of plagiogranite complexes.

Thus, in the Lebedev pluton one observes the development of two closely related formational types: the gabbro-pyroxenite-dunite type, represented by the early gabbroids, and the plagiogranite type. However, between the gabbroids and granitoids of the pluton there is a complex of similar properties: spatial and structural conjugacy, closeness of age, and a certain continuity in composition (a high content of the anorthite molecule in the plagioclase of the granitoids, the through-going behavior of quartz, the closeness in iron content of the mafic minerals, etc.), which provide grounds for assigning them to a group of related formations—namely, to the group of gabbro-plagiogranite formations. Yu. A. Kuznetsov explains the genesis of such groups from the standpoint of the hypothesis of vertical migration of magmatic chambers from the basalt layer into the sedimentary-metamorphic envelope [7].

In the Sayan-Altai folded region, similar combinations of magmatic formations, in our view, were manifested in the Mainsk (Western Sayan), Sarakokshinsk (Gorny Altai), and Tannu-Ola (Tuva) plutons.

LITERATURE

1. N. N. Amshinsky et al. Accessory minerals of the granitoids of Altai and methods of their study. Nedra Publishing House, 1964.

2. Bulletin of the Commission for Determining the Absolute Age of Geological Formations. Issue IV, Publishing House of the Academy of Sciences of the USSR, 1961.

3. M. M. Veselovskaya. Chemical-mineralogical investigation in the field of pyroxenes of the diopside-augite series. Proceedings of GIN, issue 86, petrographic series (No. 39), 1950.

4. V. E. Gendler. On the classification of granitoids. Soviet Geology, No. 51, 1956.

5. W. A. Deer et al. Rock-forming minerals. Mir Publishing House, 1965.

6. V. A. Kuznetsov et al. Magmatic complexes and formations of Gorny Altai. Abstracts of reports at the III All-Union Petrographic Conference in Irkutsk. Publishing House of the Siberian Branch of the Academy of Sciences of the USSR, 1963.

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

8. L. M. Kuzmin. Brief report on geological investigations in the upper part of the basin of the Lebed River, a right tributary of the Biya River. Proceedings of the Siberian Branch of the Geological Committee, vol. III, issue 4, 1924.

9. B. M. Kupletsky. Quantitative-mineralogical composition of granitoids. Collection of Questions of Petrography and Mineralogy, vol. I, Publishing House of the Academy of Sciences of the USSR, 1953.

10. A. P. Lebedev. Geological-petrographic investigation in the Prikatun region (Northern Altai). Materials on the Petrography and Geochemistry of the Kuznetsk Alatau and Altai. Publishing House of the Academy of Sciences of the USSR, 1937.

11. V. S. Sobolev. The significance of the iron content of femic minerals and auxiliary diagrams for determining the composition of biotite, hornblendes, and rhombic pyroxenes. Mineralogical Collection of the Lvov Geological Society at the University, No. 4, 1950.

12. V. E. Tröger. Tables for the optical determination of rock-forming minerals. Gosgeoltekhizdat, 1958.