PROCEEDINGS

of the Tomsk Order of the Red Banner of Labor Polytechnic Institute named after S. M. Kirov

Vol. 165　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1969

ON THE DIKE COMPLEX OF THE KOMMUNAR ORE FIELD (KHAKASSIA)

A. F. Korobeinikov, L. G. Osipov, I. G. Chinakov

(Presented by Professor A. M. Kuzmin)

Until recently, no sufficiently complete study of the dike formations of the Kommunar district had been carried out, although the spatial confinement of certain gold-ore occurrences to the junction nodes of major faults with dikes had been noted [14]. Therefore, on the basis of materials obtained during detailed geological-structural mapping of the ore field, the authors have attempted to summarize the data accumulated on this question.

The general geological position of the district is determined by its location on the eastern slope of the Kuznetsk Alatau, within the Iyus–Syi structural-facies zone, characterized by a great thickness (16–18 km) of Upper Proterozoic, Lower and Middle Cambrian deposits of geosynclinal type [2, 12]. These formations are gathered into large folds of submeridional and NW strike, complicated by folds of the second, third, and higher orders. The principal plicative structure of the district is the Kommunar anticline, which to the ENE is succeeded by the Syi–Efremov syncline [12]. The ore field is situated on the eastern limb of the named anticline, near its axial line, and is composed of rocks of diabase-porphyrite and volcanogenic-sedimentary sequences of Lower Paleozoic [14] or possibly even Precambrian [6] age. The rocks of both sequences are cut by small subconcordant bodies of uralitized gabbro-diorites, by the large Solgon granodiorite massif (an intrusion of quartz monzonites according to A. Ya. Bulynnikov), and by small stock- and dike-like bodies of olivine gabbro and gabbro-porphyrites, genetically connected most likely with a Devonian gabbro-syenite intrusion.

The granodiorite massif is composed of rocks of three intrusive phases: early—augite and augite-hypersthene diorites; middle—granodiorites, quartz diorites, and monzonites; and late—fine-grained granites and syenites. In mineralogical-petrographic composition and petrochemical features (Figs. 1, 2), the formations of the Solgon pluton correlate well with the rocks of the Ulen-Tuim granitoid complex of Upper Cambrian–Lower Ordovician age [5, 13] and belong to the group of granitoid formations of variegated composition [9]. For the granodiorites of the Solgon massif, the potassium-argon method has determined an absolute age of 476 million years, which permits the age of the granodiorite intrusion to be considered Salairian.

The vein series of intrusive rocks is represented by numerous dikes ranging from acidic to basic in composition. The dikes are located chiefly within the broad near-contact aureole of the Solgon intrusive body. On the basis of mutual intersections of dike bodies [8], three age groups may be distinguished among them. The first

Fig. 1. Petrochemical diagram of rocks of the Biya gabbro-diorite (open circles) and granodiorite (filled circles) intrusive complexes of Kommunar (after the method of A. N. Zavaritsky [4]). 1 — porphyritic and fine-grained uralitized diorites and gabbro-diorites of the Biya complex; 2 — diorites and granodiorites of the Solgon massif; 3 — vein series of intrusive rocks of Kommunar; 4 — rocks of the Martai granitoid complex 3; 5 — rocks of the Ulen-Tuim granitoid complex; 6 — typical rocks according to R. Daly.

group comprises isolated dikes of diorite porphyrites and fine-grained diorites-I, cut by granodiorites. The emplacement of these dikes is apparently connected with augite diorites of the early phase of intrusion.

of the granodiorite complex. The second group, genetically associated with the granodiorite intrusion, includes the main number of all dike bodies of the ore field and is subdivided into two age subgroups (in the order of their emplacement): a) diorite and labradorite porphyrites-II, monzonites, fine-grained diorites-II, microdiorites, spessartites, kersantites, vogesites, odinites, syenite-porphyries, quartz porphyries; b) pegmatites and aplites. Many dikes cut the rocks

Fig. 2. Diagram of the alkalinity modulus \((\varphi)\) of erupted granitoid rocks of the Kommunar ore field (open circles—rocks of the Solgon intrusive; filled circles—dike rocks). I—ultrabasic, II—basic, III—intermediate, IV—acidic groups of rocks according to I. V. Luchitskii [10]. Chemical analyses of the rocks are given in Table 2.

of the Solgon massif or contain xenoliths of granodiorite and tonalite composition. The association of dike and hydrothermal formations with the same systems of tectonic fractures is established, which probably indicates a common structural plan of deformation during the period of dike formation and subsequent gold mineralization, as well as inheritance of the fracture structures that arose [7]. The latter led to the formation of complexly constructed dike bodies of varied petrographic composition: diorite porphyrites and fine-grained diorites. In this case each subsequent portion of magmatic melt was usually emplaced in the middle of a previously formed dike body and formed a complex dike with distinct contacts, chilled zones, flow traces, and exocontact alterations. The dikes of the first and second groups are pre-ore. The third group consists of dikes of olivine gabbro-porphyrites and subalkaline diabase porphyrites, apparently associated with a younger Devonian (?) gabbro-syenite intrusion. They sometimes form fairly thick (5–12 m) bodies with a length of up to the first hundreds of meters and cut the diorites of the Solgon massif. Evidently, the formation of these dikes followed the gold mineralization, since they are unaltered and devoid of quartz-ore mineralization, although they are located in zones of intense hydrothermal metamorphism and mineraliza-

of the Solgon area, while dikes of subalkaline diabase porphyrites cut quartz veinlets [8].

Diorite porphyrites-I are porphyritic rocks of massive texture, composed of sparse and large (8–9 mm) prismatic phenocrysts of plagioclase No. 46–49 and pyroxene and a fine-grained plagioclase–pyroxene groundmass. The plagioclase of the porphyritic segregations (up to 10% of the total rock volume) is often deformed, with curved and crushed twin lamellae and traces of slip along twin seams. Pyroxene-augite (up to 3–5%) is colorless or pale brownish, often twinned and deformed. The groundmass consists of idiomorphic small (up to 0.05 mm) grains of augite (up to 30%), andesine No. 42–43 (up to 60%), and xenomorphic quartz. The accessory minerals are apatite and magnetite. Among secondary minerals, tremolite-actinolite is widespread; it rims augite with a colorless or slightly greenish border and sometimes replaces it entirely. Amphibolization of pyroxenes is accompanied by the separation of a fine dusting of magnetite. Pyroxene and amphiboles are replaced by biotite, and chlorite and epidote in turn develop after the biotite. Sericite, carbonates, and zoisite develop after the plagioclases. The optical properties of the minerals of all dike rocks are summarized in Table 1.

Fine-grained diorites-I are dark-gray dense rocks, often hornfelsed, and consist of plagioclase No. 31–32 (up to 60%), green hornblende with grain size 0.2–0.3 mm (up to 30%), biotite, and rare orthoclase. In thin sections a dioritic texture is established, characterized by equal idiomorphism of plagioclase and hornblende. The accessory minerals are apatite and magnetite. Secondary minerals are represented by sericite, fine-acicular actinolite, pennine, and epidote. Hornfelsed varieties acquire a microgranoblastic texture and are composed of subisometric grains of plagioclase No. 30–32, monoclinic pyroxene (instead of uralitic hornblende), and green hornblende. Sometimes even in a single thin section gradual transitions are observed from a dioritic to a hornfelsic texture.

Diorite porphyrites-II are represented by pyroxene and hornblende varieties, with transitional rocks in which the porphyroblasts are composed of augite and hornblende. The pyroxene varieties are dark greenish-gray rocks with large (up to 1–2 cm) porphyroblasts of andesine No. 45–48 and augite, with a finely prismatic-grained groundmass; with an increase in the amount of quartz, its texture passes into a hypidiomorphic-granular one, owing to the sharp xenomorphism of the latter. The cementing mass consists of andesine No. 36–39 (up to 65%), individual grains of orthoclase, green hornblende (up to 20%), rare augite, and xenomorphic quartz (3–7%). Accessory minerals are represented by apatite, sphene, zircon, magnetite, and pyrite. Among the secondary minerals there are green hornblende, which rims and replaces augite; actinolite, prehnite, biotite, and chlorite, replacing primary hornblende; sericite, epidote, and zoisite, which corrode the plagioclases.

Hornblende diorite porphyrites-II do not differ in outward appearance from the pyroxene ones. Porphyroblasts up to 1.5 cm in size are represented by andesine No. 46–47 and brown hornblende. The latter is often zonal, the zoning being most distinct in the marginal parts of the grains. The mesostasis consists of prismatic-tabular andesine No. 36–38 and hornblende with grain size 0.08–0.2 mm. The accessory minerals are apatite, sphene, magnetite, and pyrite. Sec-

Table 1

Optical properties of rock-forming minerals of the dike rocks of the Kommunar field

Continuation of Table 1

Continuation of Table I

The primary minerals are represented by colorless and green amphibole of the actinolite series, replacing brown hornblende. The green amphibole, in turn, is replaced by chlorite and epidote. Sericite and pelite develop on the plagioclases.

Labradorite porphyrites, in external appearance, are similar to diorite porphyrites and differ from the latter only in their dense aphanitic groundmass of dark color with a characteristic conchoidal fracture. In thin sections a porphyritic structure is observed, with a hypidiomorphic or pilotaxitic mesostasis, characterized by a subparallel arrangement of plagioclase microlites cemented by recrystallized glass. Porphyritic segregations, in an amount of 12–13%, are represented by labradorite No. 55–59 up to 1 cm in size, colorless augite, diopside, and, occasionally, dark-brown titanaugite. Pyroxenes are usually more idiomorphic than plagioclases and are often encountered as poikilitic inclusions in feldspars. The groundmass is composed of plagioclase No. 46–53 in the form of microlites and thin tablets, augite, diopside, and brown and green hornblende. Quartz is present more often in the coarser-grained rocks and is always sharply xenomorphic. Areas of weakly recrystallized glass with radial-fibrous extinction are common. Among the accessory minerals, apatite, sphene, and magnetite are developed. Among the secondary minerals, green hornblende predominates, replacing pyroxenes; pale-green actinolite develops on the primary amphibole; the glass is replaced by chlorite; and the plagioclases are often completely sericitized and saussuritized.

Fine-grained diorites-II are dense fine-grained rocks of dark-gray color. Under the microscope a hypidiomorphic-granular structure is observed, characterized by xenomorphism of quartz and idiomorphism of plagioclases relative to the mafic minerals. Plagioclase No. 39–42 (60–65%) is commonly deformed. Quartz, in the form of xenomorphic grains, occurs in amounts from 1–3 to 5–7%, together with individual grains of orthoclase. Brown and green hornblende occurs as prismatic-acicular grains, and biotite as small flakes. Augite is present as a secondary mineral in more basic, quartz-free varieties. Among the accessory minerals, apatite, sphene, zircon, and magnetite have been identified. The secondary minerals are represented by actinolite, biotite, and chlorite, replacing the primary amphiboles. Pyroxene is replaced by green hornblende, biotite, and magnetite; moreover, biotite and secondary amphibole develop along cleavage, and magnetite along cracks. Sericite and matted-fibrous actinolite develop on the plagioclases. Epidote and calcite, which corrode all the rock-forming minerals, are frequently encountered.

Lamprophyres within the ore field are represented by spessartites, kersantites, vogesites, and odinites. The latter compose thin veins or marginal parts of complexly built spessartite dike bodies.

Spessartites are dense dark-gray fine-grained rocks with a weakly expressed porphyritic structure and are composed of plagioclases, amphiboles, and pyroxenes. Porphyroblasts (5–12%), 2–8 mm in size, are represented by brownish-green hornblende of acicular habit, often twinned according to (100). The structure of the groundmass is hypidiomorphic-granular and is characterized by pronounced idiomorphism of the mafic minerals relative to the plagioclases. Plagioclase No. 30–37 makes up as much as 53–57%; the grain size is 0.5–0.6 mm and smaller. The hornblende of the mesostasis is analogous to that of the porphyroblasts, but its grain size is 0.2–0.3 mm and it constitutes up to 30%.

Augite (up to 3–5%) is colorless or pale brownish, sometimes twinned on (100).

Kersantites are dense medium- and coarse-grained dark-gray rocks consisting of 45–50% biotite, 30–40% andesine No. 28–32, and about 10% orthoclase. The texture is porphyritic; the phenocrysts are represented by biotite flakes 0.5–0.9 cm in size.

Monzonites are porphyritic rocks with a light-gray fine-grained (0.05–0.15 mm) groundmass. Macroscopically they differ from diorite porphyrites by their pinkish-whitish appearance. Phenocrysts, 5–8 mm in size, are represented by plagioclase tablets No. 40–45 (10–15%). The texture of the groundmass is monzonitic and is characterized by a greater idiomorphism of plagioclase relative to orthoclase; sometimes plagioclase has the character of poikilitic inclusions in orthoclase. The mineralogical composition of the matrix is represented by andesine No. 35–40 (40–45%), orthoclase (30–35%), and green hornblende (20%). The amphibole is usually twinned on (010), and the twins are often deformed. Accessory minerals are zircon and pyrite. Secondary minerals are sericite and zoisite, replacing plagioclases, and pale-green fibrous actinolite, replacing hornblende. Actinolite, in the form of fine acicular aggregates, also penetrates the feldspars, forming in them an irregular lattice.

Quartz porphyries are light-gray fine-grained rocks of porphyritic texture. The phenocrysts (up to 7–10%) consist of quartz grains of irregular, more rarely well-bounded form, 2–3 mm in size. The quartz is often fractured, the cracks being filled with a mesostasis mineral. Much more rarely, rounded-isometric grains of orthoclase occur. In individual grains, tabular segregations of andesine No. 30–33 are observed. Under the microscope, a microgranitic texture of the groundmass is revealed, characterized by the idiomorphism of quartz relative to orthoclase and plagioclase No. 25–28. The amount of plagioclase is approximately equal to that of orthoclase and together makes up as much as 65% of the total mineralogical composition of the rock matrix. Prismatic and lathlike crystals of green hornblende sometimes appear. Accessory minerals are apatite, sphene, zircon, and magnetite; apatite not infrequently gives poikilitic inclusions in sphene. Secondary minerals are sericite, carbonate, and epidote, developing along plagioclases, and tremolite, more rarely chlorite, corroding hornblende.

Syenite-porphyries are fine-grained pinkish-gray rocks consisting of orthoclase, plagioclase, quartz, hornblende, and biotite. In thin sections, a porphyritic texture with a hypidiomorphic-granular groundmass is revealed. In quartz-free varieties, the feldspars and mafic components are equally idiomorphic. The phenocrysts are represented by orthoclase and plagioclase No. 17–18, 2–3 mm in size. The mesostasis consists of orthoclase (65–70%), brown hornblende (10–20%), and xenomorphic quartz. In some varieties, biotite takes the place of hornblende. Among the accessories, apatite, sphene, zircon, monazite, and magnetite have been identified. Secondary minerals are represented by green hornblende replacing the brown; at the same time a fine-grained aggregate of sphene arises. Green hornblende and biotite are replaced by pennine. Biotite often contains a sagenitic lattice of rutile. Sericite and calcite develop along the plagioclases.

Diorite-pegmatites are usually zonal in structure; the marginal parts of the veins are composed of plagioclase No. 45–48 (up to 50%), green hornblende (up to 30%), and quartz (up to 5%). Toward the center of the veins the amount of amphibole sharply decreases, even to its complete disappearance. One—

At the same time flakes of muscovite appear, and the plagioclase becomes more acidic: No. 35–36, with an increase in grain size toward the center of the veins, up to the formation of drusy textures. Here crystals of plagioclase No. 30–32 (80–85%), quartz (5–7±), and coarse-scaly muscovite reach 4–5 cm. Usually the contacts of the pegmatoid bodies are sharp and rectilinear, but sometimes the pegmatite gradually passes, through coarse-grained pegmatoid diorite, into ordinary medium-grained diorite.

Granite pegmatites, unlike diorite pegmatites, consist of orthoclase, quartz, and muscovite and do not contain mafic components or plagioclase.

Granite aplites are light-gray fine- and medium-grained rocks which, under the microscope, reveal a porphyritic structure with hornblende. In thin sections an aplitic, glomeroporphyritic, and micropegmatitic structure is observed. The glomeroporphyritic structure is characterized by porphyritic segregations of andesine No. 31–33 and orthoclase, with a quartz–feldspar groundmass of hypidiomorphic-granular structure, distinguished by the xenomorphism of quartz in relation to oligoclase No. 16–17. The micropegmatitic structure is distinguished by wormlike intergrowths of quartz in feldspars. Orthoclase and microcline (up to 30%) often form perthitic intergrowths with oligoclase No. 15–17 and 20–25, and in porphyroblasts even No. 31–32. Quartz (up to 30%) often gives micropegmatitic intergrowths with feldspars or, in the form of rims, overgrows the latter. Brown or greenish-brown biotite sometimes contains inclusions of zircon and apatite. Green hornblende is rare and is usually replaced by biotite. Accessory minerals are represented by apatite, sphene, zircon, and magnetite.

Plagiogranite aplites are leucocratic fine-grained rocks which, under the microscope, reveal a porphyritic structure with an aplitic groundmass. The porphyroblasts are composed of oligoclase No. 13–14 (5–7%), 2–3 mm in size, and rarely microcline. The groundmass of the rock consists of oligoclase No. 10–12 (75–80%), 0.1–0.2 mm in size, and quartz (up to 18%). Among accessory minerals, apatite, sphene, and magnetite have been found.

Diorite aplites are leucocratic fine-grained rocks composed of feldspars, quartz, and hornblende. The structure is prismatic-granular, with uniform idiomorphism of the plagioclases and amphiboles. Plagioclase No. 32–35 (up to 80%) occurs as prismatic grains. Hornblende of prismatic habit (up to 10–15%). Sometimes actinolite is found together with amphibole. Quartz is usually xenomorphic. Accessories: apatite, sphene, and magnetite. Among secondary minerals, sericite and epidote, developing after plagioclases, and actinolite, chlorite, and biotite after hornblende have been established.

Syenite aplites are characterized by an aplitic structure and an almost complete absence of mafic minerals. Composition of the rock: orthoclase (up to 40%), oligoclase No. 18 (45–50%), isolated grains of biotite, green hornblende, quartz, apatite, sphene, zircon, monazite, and magnetite.

Olivine gabbro-porphyrites are very fresh, dense rocks of grayish-black color. In thin sections a porphyritic structure is established. The porphyroblasts (up to 50–70%) are composed of short-prismatic augite, 0.3–2.5 cm in size. It often contains small rounded-isometric, 0.2–1 mm in size, intergrowths of olivine, or forms separate clustered segregations with it. The amount of olivine in the rock is up to 5–13%. Plagioclase of the porphyritic segregations, 0.3–1.9 cm in size, is represented by labradorite No. 54–56, often zoned and compos-

amounts to 60–70%. The basic rocks are also composed of labrador No. 50–53, augite, and more rarely olivine, with a typically gabbroic structure and a grain size of 0.05–0.15 mm. Among accessory minerals, sphene, magnetite, and titanomagnetite have been identified. Secondary alterations are manifested only very weakly and are expressed in the replacement of pyroxene by biotite and, simultaneously, in the separation of ore dust and serpentinization of olivine. Pinkish-yellow bowlingite often develops along the margins of olivine grains or along cracks in them. The plagioclase porphyroblast and the groundmass have an entirely fresh appearance, and only isolated sericite flakes and the very finest epidote grains are found in them.

Subalkaline diabase porphyrites are characterized by a pilotaxitic structure of the basis, caused by the subparallel arrangement of plagioclase microlites cemented by weakly recrystallized glass. The porphyroblasts are represented by labrador No. 59–65, more rarely by diopside and augite. In contrast to the rocks of the dikes of the second group, such hysterogenic minerals as saussurite, chlorite, and amphiboles are completely absent from the subalkaline diabase porphyrites. A distinctive feature of the composition of these rocks is the elevated content of orthoclase and of rare, semitransparent and isotropic analcime.

Some Features of the Petrochemistry and Geochemical Characteristics of the Rocks of the Dike Complex

As already noted, in terms of structural-geological conditions of occurrence and petrographic features, the rocks of the Solgon granodiorite massif and most of the dikes of the area fit into a single magmatic complex of Salairian age. This conclusion is also confirmed by the petrochemical features of the named rocks. On the basis of numerous analyses of the rocks (Table 2), a diagram of the chemical compositions of the intrusive rocks of the area was compiled (Fig. 1), on which the compositions of the most similar rocks of the Ulen-Tuim and Martaiga granitoid complexes [3, 13] are plotted; this diagram reflects the following principal features of the rocks of the granodiorite complex.

1. In its chemistry, the granodiorite complex of rocks forms a regularly elongated swarm corresponding to the typical series of calcareous-alkaline associations (Figs. 1, 2).

2. The variation line in the alkaline field is somewhat removed from the SB line and, with the transition from basic rock varieties to acidic ones, gradually deviates to the right, which indicates an increase in the sum of alkalis. The amount of potassium regularly increases in the same direction, as is evidenced by the flattening of the vectors on the CSB plane of the diagram.

3. The regular departure and then approach of the variation line from the SB line in the CSB plane indicates the poverty of the rocks of basic and acidic composition in feldspar lime and the comparative enrichment in it of the rocks of intermediate composition.

4. In comparison with the Martaiga intrusive complex, the rocks of the Solgon intrusive are characterized by somewhat increased alkalinity; moreover, as in the rocks of the Ulen-Tuim granitoid complex, an increase in the content of alkaline aluminosilicates is observed from phase to phase with a decrease in the content of the anorthite molecule. At the same time, the ratio \(K_2O : Na_2O\) increases, i.e., the content of potassium aluminosilicates in the rocks rises somewhat in comparison with sodium ones.

When considering the chemical compositions of the dike rocks, attention is drawn...

Attention is drawn to the circumstance that the figurative points of the first two groups of dike rocks are located in the field of the figurative points of the rocks of the Solgon massif. This, on the one hand, emphasizes their genetic relationship, and, on the other, the regular change in the chemical composition of the rocks. The separate genetic groups of dikes that have been distinguished are characterized by the following petrochemical features.

1. Diorite porphyrites-I and fine-grained diorites-I of the first group (Nos. 27, 29) are characterized by an elevated silica content \((S = 62.5—63.3)\), an elevated content of femic components \((b = 22.1)\), and a relative undersaturation in alkalies with a simultaneous excess of lime.

2. The chemical composition of the most acid varieties of dikes of the second group (granite-aplites, Nos. 20, 21) is characterized by a very high silica content. They are characterized by a somewhat elevated alkali content and an insignificant amount of feldspathic lime. In general, the chemical composition of the dike rocks of the second age group varies within wide limits (Fig. 1): the silica content regularly decreases from monzonites (No. 28) to diorite porphyrites. In the monzonite there is a sharp oversaturation in alumina, which finds its mineralogical expression in the high content of orthoclase. The content of free lime varies within wide limits, and the variation line of the diorite porphyrites in the CSB plane has the form of a smooth sinusoid. The subalkaline diabase porphyrite of the third age group of dikes is characterized by a very low silica content with an elevated value of femic components. An elevated alkali content is noted, with a simultaneous decrease in feldspathic lime (Fig. 2). This brings them closer to teschenites from the Devonian basins of the Minusinsk trough, described by I. V. Luchitskii [11]. In any case, both for Devonian dikes of basic composition and for diabase porphyrites of the third group, a subalkaline tendency is characteristic, which is possibly due to the alkaline character of autometasomatism.

In order to clarify the geochemical continuity between the dikes and the rocks of the granodiorite massif, we used the results of semiquantitative and quantitative spectral analyses of samples from the rocks and accessory magnetite, carried out in the laboratory of the Tomsk Polytechnic Institute.

In the rocks of the Solgon intrusive the following trace elements have been established: Mn, Ti, Ni, Co, V, Cr, Zr, Zn, Pb, Sn, Mo, Cu, Ga, in amounts from thousandths to hundredths of a percent (Table 3). The most widespread element is Ti, which is present in amounts from 0.03 to 0.3%. The main amount of this element enters into the composition of augite and amphiboles, which are the principal rock-forming minerals, and sphene, a very widespread accessory mineral. The behavior of Cu, V, Cr, and Zr is very characteristic; moreover, hornblende leucodiorites and granodiorites of the second phase of intrusion are characterized by an elevated content of Cu and V up to 0.03% and Zr up to 0.01%, whereas augite meladiorites show a consistently elevated content of Cr up to 0.01%.

The most essential trace elements of the rocks of the dike series are Ti, Cu, Sn, and Mo, in amounts from thousandths to 0.1–0.3%. In the rocks of the first genetic group of dikes, the trace elements Mn, Ti, Ni, Co, V, Cr, Cu, and Zn are present. By the absence of Zr, Pb, Mo, Sn and by the elevated Cr content (up to 0.01–0.08%), a similarity to the early phase of intrusion of the granodiorite intrusion is revealed.

Dikes of the second age group contain the trace elements: Mn,

Table 2

Chemical composition of intrusive rocks of the Kommunar ore field

1, 2, 3, 4, 5, 6, 7, 8, 9 — porphyritic, fine-grained uralitized diorites and gabbro-diorites of the Boisk intrusive complex; Solgonskii intrusive: 9 and 10 — augite diorite; 11 — granodiorites; 12 — quartz diorites; 13, 14, 15, 16, 17, 19 — diorites and meladiorites; 18 — xenolith of diorite (tonalite) in a dike of hornblende diorite porphyrite (Podlunnyi Golets); vein series of intrusive rocks: 20, 21 — granite-aplite; 21, 23, 24, 25, 26, 27 — diorite porphyrite; 28 — syenite-diorite porphyrite (monzonite); 29 — fine-grained diorite; 30, 31, 22 — berezitized diorite; 32 — subalkaline diabase porphyrite (teschenite?); 33 — syenite; 34 — syenite-porphyry; 35 — plagiosyenite; 36 — quartz porphyry; Martayginskii intrusive complex (after T. M. Dembo, 1956); 37 — gabbro-diorite; 38, 39 — quartz diorite; 40 — quartz monzonite; 41, 42, 43 — granodiorite; the chemical analyses were performed in the central laboratory of KGU.

Ulen-Tuimskii intrusive complex [11]: 44 — biotite-hornblende granite of the Tygertysh massif; 45 — biotite granite of the Askiz massif; 48 — gabbro-diorite of the Tygertysh massif; 49 — diorite of the Uibat massif; 50 — granodiorite of the Ulen massif; 46 — granosyenite of the Tygertysh massif; 47 — diorite of the Ulen massif.

Average chemical composition of rocks according to R. Daly: 51 — granite-aplite; 52 — quartz monzonite; 53 — quartz diorite; 54 — syenite; 55 — monzonite; 56 — gabbro; 57 — spessartite; 58 — teschenite.

Trace elements in intrusive rocks of the Kommunar ore field

Table 3

Ti, Ni, Co, V, Cr, Zr, Pb, Zn, Cu, Mo, Sn from thousandths to hundredths of a percent. A highly characteristic elevated content of Cu, Zn, Zr from 0.01 to 0.03%, a reduced chromium content in comparison with the dikes of the first age group, and an increase in vanadium to 0.08%, as well as the appearance of Sn and Mo. By these features a similarity is revealed in the behavior of trace elements in the dikes, leucodiorites, and granodiorites of the second phase of the Solgon intrusion.

In contrast to the dike rocks of the first and second groups, in the dikes of the third group, in addition to Mn, Ni, Co, Cr, Cu, and Zn, an elevated content of Ti and V is constantly observed in amounts from 0.1 to 0.2%, and there is an almost complete absence of Zr, Pb, Sn, and Mo, which are highly characteristic of the dikes of the second group (Table 3).

Thus, a detailed study of the mineralogical-petrographic composition of the dikes and intrusive rocks of the granodiorite massif, as well as clarification of their petrochemical and geochemical features, gives grounds to assert that the indicated rocks have many common mineralogical-chemical-geochemical characteristics, which with a sufficient degree of reliability allow one to speak of their genetic connection. According to the classification of Kh. M. Abdullaev [1], they should be assigned to the group of intramagmatic dikes. At the same time, the dikes of the first age group probably belong to synintrusive types, and those of the second—to postintrusive types. At the same time, establishing the genetic kinship of these formations makes it possible to approach more closely the clarification of the genetic connection of the gold mineralization with the granodiorite intrusion, if one takes into account that dikes of the second group often carry gold mineralization and prove to be paragenetically connected with the ore mineralization, which is considered in more detail in a separate communication [8].

REFERENCES

1. Kh. M. Abdullaev. Dikes and Ore Mineralization. Gosgeolizdat, 1957.

2. Geology of the USSR, vol. XV, part 1. Gosgeoltekhizdat, 1961.

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