Characterization of Yubileyny Field Ore Potential Based on New Structure-Substance Information

Spatial-genetic relation of a polycomponent ore mineralization (Au, Ag, PGE, Cu, Pb, Zn, Ni) with dynamometamorphic complex, formed by the picrite-komatiite-tholeiite series rocks of Kelyana-Irokinda greenstone belt, is identified. Productivity of various ore mineralization morphostructural types (quartz-vein, zones of veining and sulfide dissemination) differing in mineral composition and content of useful components is considered. It is shown that the main industrial value is represented by veined and disseminated ores with relatively poor useful components content, but at the same time forming large-capacity ore zones. The occurrence extent, localization conditions and ore zones hyperthetical resources are favorable for the production of economically cost-effective open pit (quarry) mining operations. An effective sampling method is recommended to carry out the prospect and exploration of large-capacity deposits on the Yubileyny field and other similar to its Transbaikalia ore objects.


Introduction
Prospecting and exploration works on the area of the Yubileyny ore field were widely carried out by production organizations (Irkutskgeology, "Agrodorspetsstroy" company) in the 60 -90 years of the last century.Upon these works results, the Yubileyny ore field (Figure 1) was classified as industrial auriferous deposits of medium extent.It is identified that its productivity is determined by L. I. Yalovik, A. V. Tatarinov DOI: 10.4236/gm.2019.91001 2 Geomaterials the hydrothermal quartz-vein mineralization type, characterized by high Au (up to 775 g/t) and Ag (up to 458.3 g/t) content.A total of 149 quartz veins were discovered.From them with industrial contents, 14 veins opened by mining workings.The studied industrial ore quartz veins parameters are: length 350 -1000 m, capacity 0.1 -0.97 m, the content of Au-1.6 -211 g/t, Ag-159 -641.5 g/t.It is identified that the gold bulk (90%) is in free form, characterizing by consistently high fineness values (880 -940) [1].
Figure 1.Mineragenic scheme of the Muya district South-Western part (materials of different years geological survey works are used).Geomaterials worked for less than a year.Its work had been stopped because of the low gold content in the ores, which could not ensure the profitability of underground mining.Thus, the results of all previously conducted exploration works did not allow to put on the balance of the significant gold reserves economically viable for underground mining (tunnel) method.Herewith, the possible use of the veined type deposits by open (quarry) method was not considered.
A.I. Zhilyaeva with co-authors [1] according to the probing analysis results also confirmed the non-industrial auriferousness, widely developed in the ore field, of beresitized and listwenitized rocks containing sulfide mineralization.
Upon their data, the gold content in beresites is Ambiguous Au and Ag contents characteristics complicate an objective assessment of the veined and disseminated mineralization productivity, the prospect perspectives of commercial deposits.Therefore, our research was focused on the study of lithological and petrographic control factors, material composition and productivity of various morphostructural types of ore mineralization in order to identify the distribution extent, except Au and Ag, of other useful components, the account of which could increase the value of extracted complex ores and thereby ensure the economic profitability of open-pit mining.

Brief Structural and Geological Characteristics of the Ore Field
Ore deposits of the Yubileyny field (Figure 1) is located on the Northern flank of Kelyana-Irokinda auriferous zone (240 × 25 × 35 km), previously allocated [2], as part of Bambuyka structural-metallogenic subzone, in its turn belonging to the Barguzin-Muya structural-metallogenic zone.Within Kelyana-Irokinda auriferous zone, which should be correctly called mineragenic, except auriferous objects in the rank of Yubileyny, Irbo and Irokinda deposits (located on the South-Eastern zone continuation), such mineral occurrence as Ikibzyak, Iligir, Bogodikan, Sosnovy site et al. and also Kelyana mercury deposit are known to be poorly studied.All of them, as shown in recent investigations [3] [4] [5], are located within the Vendian-Riphean Kelyana-Irokinda riftogenic greenstone belt, which was previously considered as one of the lower Proterozoic Baikal-Vitim greenstone belt branches due to the lack of isotopic dating [6].The primary riftogenic Kelyana-Irokinda greenstone belt structure is overlaid by the regional charriage-shear zone (Figure 2), the formation of which was followed by dynamometamorphic Geomaterials Figure 2. The Yubileyny ore field position on the regional geological section.
transformations of the primary volcanic-plutonic association rocks and synchronous ore formation.
For the mentioned Kelyana-Irokinda greenstone belt auriferous objects (of the homonymous metallogenic zone) a spatial-genetic relation with dynamometamorphic complexes, formed on the picrite-komatiite-tholeiite series rocks (Table 1) is identified, including high silica magnesium boninite-like rocks group [4] [5], that is a characteristic feature of Archean greenstone belts [7].The same volcano-plutonic series of high-magnesia rocks of the Vendian-Riphean age is proper to precious-metal deposits and occurrences localized in the neighboring Gukit-Parama greenstone belt and also, located further South, and more detailed studied, to Selenga-Vitim one [4].Among the rocks of the productive dynamometamorphic complex on the Yubileyny ore field the massive fine-grained dark green amphibolites, plagioclase-amphibole rocks (tunnel 6) in the form of rare small relics (Table 1, samples YUB-90 and YUB-91) are met.They are composed by actinolite sheaf aggregates and plagioclase of the andesine-oligoclase series.Tremolite and aegirine were identified as secondary minerals.Accessory rutile and ilmenite were diagnosed.It is assumed that these rocks originated on the high-magnesia vulcanites.On the Northern flank of the ore field, geologists-surveyors identified hornblende amphibolites (Figure 3), the formation of which is associated with the metamorphism of the epidote-amphibolite facies, to which the Muya complex gabbroids were subjected.These are rocks composed of green hornblende, plagioclase (andesine-oligoclase); of secondary minerals, biotite, actinolite, rarely epidote are identified.The structure is granoblastic one, minerals arrangement is parallel-linear one, which say us abou their dynamometamorphic nature.From the accessory minerals, the ilmenite, sphene, rutile, magnetite, pyrrhotite, chalcopyrite were found.Perhaps the initial rock for the hornblende amphibolites formation was not the Muya complex gabbroids but pyroxenite komatiites like those that discovered on Irbo field [8], and earlier in Geomaterials 1-amphibolites (on pyroxenite komatiites?); 2-Muya complex cataclastic diorite, granodiorites, plagiogranites; 3-chlorite-plagioclase-amphibole mylonits on amphibolite; 4-Muscovite-quartz-plagioclase mylonites on granitoides of the Muya complex; 5-plagioclase mylonites on granitoides of the Muya complex; 6-7-expected ore zones (6-albite-quartz-sericite dynamoslates, 7-dynamoslates of chlorite-sericite-albite-quartz composition); 8-auriferous quartz veins.Note that the picrite-komatiite series of mesoarchean Olondo greenstone belt differ from the Vendian-Riphean belts by the absence of the boninites-like siliceous rocks group in its composition (Table 1).The structure of the crush zone steep-falling part in morphology and construction corresponds to the autoclastic lenticular-lamellar melange [15].It marks the seam of a listric thrust.In this seam, the greenstone belt primary volcano plutonic rocks and the surrounding granitoids have been transformed into an ore-bearing dynamometamorphic complex.

Material Composition Peculiar Properties of Dynamometamorphic Rocks
As a result of tectonic-metamorphic changes in the primary rocks of the Vendian-Riphean age, up to the complete disappearance of the primary minerals and their primary structure, a dynamometamorphic complex was formed, represented by cataclasite, milonite and dynamoslate facies (Figure 3).and "listwenites" by composition refers to ferrodolomite and breunerite.According to our data, it crystallizes in the form of small (0.1 -0.5 mm) porphyroblasts and aggregate clusters.Simultaneously with it, small veins of ore granular quartz are formed.On thin, parallel to foliation, cracks in dynamoslates the kaolinite in minor amounts develops.Dynamoslates are the vein comprising medium, the disseminated-veined zones with ore mineralization are concentrated in them too.Dynamoslates (ore-formational type of "mylonitization and foliation zones" by [16]) are feasible to regard as prospecting objects in auriferous zones.
Based on the data analysis presented in Table 2 and Table 3, the geochemical elements behavior and concentration peculiarities are revealed during the ore-hosting dynamometamorphic complex formation of the Yubileyny field.For dynamometamorphytes group formed on magmatic rocks of the picrite-komatiitetholeiite series: Dynamoslates mainly inherit the contents levels of most mylonites microelements, except of V and Au higher values.
It should be noted that dynamoslates ore geochemical specialization (Table 2), which are the products of tectonic-metamorphic transformations of both basic and medium magmatic rocks, is very close.It is the result of the geochemical specificity inheritance of the primary volcano plutonic rocks pyrite-komatiitetholeiite series of Kelyana-Irokinda greenstone belt.Petrographic and mineralogical-geochemical signs of dynamometamorphic ore-hosting complex spatial-genetic relation with rocks of this series are as follows: 1) in dynamoslates, in the form of relics, amphibolites with basalts "shaddy" structure and preserved in the amphibole mass primary anortite are detected; 2) nickel, chrome and vanadium geochemical specialization is inherited by dynamometamorphytes, including ore quartz (Table 4).The presence of relic pentlandite and newly formed nickel-containing pyrite and pyrrhotite in the latter ones was identified (Table 5); 3) rutile, met in dynamometamorphytes, contains V to 0.92 wt% and the chlorite of the "beresites" and "listwenites " are enriched with Cr [1]; 4) gold from quartz veins contains an admixture of Pt up to 0.13 wt% [1].
In the formation of Kelyana-Irokinda mineragenic zone tectonic structures three deformation stages [17] are allocated: 1) late Riphean thrust, 2) after the Cambrian thrusts and upthrows, 3) the Paleozoic left shear disturbances.Three time steps of dynamometamorphic (deformation-metamorphic) events should correspond them.Our research showed that Irbo deposit [8], jointed [1] with the  Table 3. Noble metal contents in rocks of the ore-hosting dynamometamorphic complex according to the data of the atomic absorption analysis (analysts L. V. Mitrofanova and A. A. Tsyrenova, GIN SB RAS).The analyses were performed on the electron microscope LEO-1430VP by N.C.Karmanov.Geomaterials Yubileyny field into a single Irbo-Yubileyny ore field, its ore-forming dynamometamorphic complex is really formed in three steps (Rb-Sr Dating): the Cambrian, Devonian and Carboniferous.The Riphean age characterizes the early ore preparative magmatic stage of the Kelyana-Irokinda mineragenic zone ore-forming system.
Analogically with Irbo field, we can assume a three-step dynamometamorphysm in the Yubileyny ore field too, in the sequence: mylonites-dynamoslates, ore vein quartz [8].

Morphostructural Mineralization Types and Ores Material Composition
Ore mineralization is localized in the veins of granular in different degrees quartz, in the zones of quartz and quartz-carbonate veining, sulfidization.
All of them are mainly located in the contours of dynamoslates ore zones of the albite-quartz-Muscovite composition (see Figure 3).Not-auriferous or weakly auriferous quartz veins are commonly characteristic for cataclasites.According to exploration works, the quartz veins are characterized by tabular form, complicated with bends and crimps, perform plane dynamometamorphic bending and cleavage cracks.The quartz is milky white with transitions to gray blocky, sectionally mainly (by cracks) granular.
ore quartz veins often disintegrate into a number of lenses or pass in thin veinlets as it is proper to auriferous quartz veins of the stem type, localized in the mylonites (Irbo ore field).
Linear zones of quartz veining with a thickness of 1.5 -8 m contain from 10% -20% to 30% -40% of veinlets.The number of such zones that it is advisable to allocate as a potential ore deposits, reaches 10 -12 m while the dynamoslates zones width comprising them is from 200 to 500 m.Sulfide-quartz-carbonate veining zones possess a wider variation of the visible thickness (0.2 -2 m 10 -30 m).Their length reaches 200 m.Previously estimated Au P 2 +P 3 reserves on these areas the resources, were in the amount of 26.4 tons.
Quartz-vein type is characterized by poor-sulfide (up to 1% of sulfides), quartz and sulfide-quartz technological ores varieties.For veining zones, the same technological ore groups with mineral subtypes: gold polymetallic one with faded ores, gold-polymetallic one with boulangerite and hessite, gold-polymetallic one with arsenopyrite, boulangerite and faded ores, gold-polymetallic one with scheelite and faded ores.
About 100 ore minerals are known in quartz veins and veinlets.The most common among them are sulfides, in less degree sulphosalts of heavy metals.The rare met tellurides and native metals are very deverse (Table 6).Mineral paragenetic associations of ore quartz veins are represented by (from early to late one): quartz, quartz-pyrite, quartz-sphalerite-chalcopyrite-Galena and gold-telluride-quartz one.
Ore mineralization of sulfide disseminated zones is mainly represented by pyrite, but pyrrhotite, chalcopyrite, sphalerite, Galena, magnetite, marcasite, rutile, native gold there are in subordinate amounts.Pyrite forms cubic shape grains, uniformly distributed throughout the rock and rarely met in the form of pentagonal-dodecahedrons.Grain sizes vary from 0.01 -0.05 to 0.08 2 mm.Pyrite small grains form not seldom aggregates of irregular shape (0.8 -4 mm) and elongated separations (0.5 -3 mm), sometimes located together with kaolinite along thin cracks.Pyrite grains are fractured, contain many different ore inclusions (pyrrhotite, rutile, chalcopyrite, magnetite, pentlandite, sphalerite).Iron hydroxides develop throughout the pyrite.Pyrite not seldom associates with carbonate, quartz-carbonate veinlets too.Gold in pyrite is in a fine state.Its content is 3 -15 g/t (Table 7).
Pyrrhotite is concentrated in the chlorite and micaceous mass, forming grains, unevenly distributed in the rock.Chalcopyrite is marked in the form of separate, irregular-shaped grains of 0.05 -0.1 mm in size and in accretions with pyrrhotite, pyrite.It also associates with magnetite and rutile.Single grains are not rare in micaceous-carbonate mass.
Magnetite is met as small inclusions (0.08 -0.1 mm) of isometric form with uneven contours, sometimes forming cubic crystals (0.08 -0.12 mm).It is in close association with chlorite, chalcopyrite.There are admixtures of Ti up to 2.96%.
Marcasite is crystallized into lenticular form aggregates (0.1 -0.3 mm), closely associates with carbonate, that give an evidence of their simultaneous formation.
Pentlandite grains were found in pyrite.Their form is isometric, sizes are up to 0.1 mm.
Rutile of prismatic and needle forms is met as separate grains of the irregular form.It associates with mica, pyrite, tourmaline, hematite.As the admixtures elements, Fe (FeO up to 1.31%) and V (V 2 O 5 up to 1.35%) are identified in it.
Central low-sulphide zones of ore quartz veins carry predominantly Au-Ag-Pt mineralization, and their sulfide rims are enriched with Ru, Jr, Os, Cu, Zn, Pb, Sb, that allows us to consider them as clusters with multicomponent noble metal-polymetallic ores (Table 8).Looking at the concentrations ratio of Os, Jr, Ru due to the presence of pentlandite, nickel-containing pyrite and pyrrhotite.They can be considered as the complex nickel-noble metal ores.

Mylonite and Dynamoslate Mineralized Zones-Perspective Prospect Objects of Polycomponent Ores Large Capacity Deposits
Within the Yubileyny ore field central part, studied by mining and drilling works, the authors have allocated 8 mineralized ore zones with a visible thickness on the surface of 150 -700 m, the extent length of which is not identified, since they have not been monitored beyond the boundaries of the presented map (Figure 3).In these zones the most part of the revealed by present time ore Irokinda deposit area (8 areas with a total area of 24 km 2 ).We emphasize the fact that at least some of the most explored quartz veins enriched by noble metals enter the quarry developments contours.

Figure 3 .
Figure 3. Geological map of the Yubileyny ore field central part (used data[1] are given in our interpretation).
Cataclasites keep mineral composition and structures about 60% -80% of the initial rocks.The most common are the Muya complex cataclasites on diorites and granodiorites, which are disintegrated into sharp-angled fragments of different sizes.In the latter ones the areas with primary hypidiomorphic granular structure are being preserved.Considered cataclasite are heterogeneous in composition and construction.The partial recrystallization of finely splinted material is observed, the newly formed sericite, quartz, rarely ferrous carbonate are appeared.A mylonite rocks characteristic peculiarity of chlorite-sericite-plagioclase, sericite-plagioclase, plagioclase-amphibole, chlorite-plagioclase compositions is the preservation of the relict fragments as the spectacle porphyroclasts surrounded by the sericite and chlorite linearly-laminated aggregates.The content of the latter ones reaches 10 wt% -15 wt%.The plagioclase composition is mainly oligoclase one.In the rocks of blastomylonite variety-porphyroblastic process is manifested in the growth of cribriform prismatic albite, which replaces single oligoclase porphyroblasts.There are met also porphyroblasts of quartz, ferrous carbonate (ankerite, siderite) and pyrite.Apogranodiorite mylonites are composed by the fine-grained, fully recrystallized material of quartz-plagioclase or plagioclase-quartz composition, with sericite filamentary separations.The composition of the plagioclase is albite-oligoclase one.Quartz is scattered in the total rocks mass, there are also its lenticular-veined separations, the content of Geomaterials

1 )
at the early stage of deformational transformations at PT-conditions of the epidote-amphibolite facies (amphibolites) the most wide contents fluctuations are proper to Cr, Zn and Ba, Sn and Nd, in less degree to V, Sb, Sr, Zr, Y, La, Ce, Pt and Pd too; 2) late apoamphibolite dynamoslates, having lower concentrations levels Cr, V, Y, Pt and Pd compared with the amphibolites are characterized by higher contents of Co, Pb, Sn, Sb, Ba, Sr, Rb, Ag and especially Au, with close values of Zn, Pb, Zr, Y, Ce, Nd.Apodiorite mylonites, compared with the above-mentioned amphibolite, with wide concentrations fluctuations of Cr and V have lower their magnitudes.However, with a more contrast distribution of Pb, Sb, Sr, Rb, Ce, Nd, the maximum contents values of these elements reach larger values.They, being close in concentrations of Ag and Au with amphibolites, Pt and Pd are sharply depleted.L. I. Yalovik, A. V. Tatarinov DOI: 10.4236/gm.2019.910018 Geomaterials content in samples YUB-90-2270 g/t, YUB-11 (dynamoslate on main high-mg volcanic rocks)-1870 g/t; "-"-not found.Analyses were performed in GIN SB RAS by B.Zh. Zhalsaraev (RFA-X-Ray Fluorescent Analysis).YUB-Yubileyny fied; GIN SB RAS-Geological Institute, Siberian Branch, Russian Academy of Sciences.
quartz veins of veinlet occurrence and disseminated mineralization type are localized.The set of these morphostructural mineralization types determine the ore-bearing zones high potential for large-capacity ore deposits prospecting of multicomponent composition, in which the noble metals (Au, Ag and EPG) take place of leading position, and polymetals (Cu, Pb, Zn), Ni, Co, Sb, Zr have secondary industrial value (minor components).It is known that large-capacity deposits are characterized by significantly lower industrial contents of ore components, compared with ordinary ones, by the dominance of veined-disseminated and disseminated mineralization types, as well as by capacity parameters that allow them to operate in an open (quarry) way.Zones of disseminated sulfide mineralization are especially relevant for the prospecting, which are not only characteristic to the Yubileyny ore field, but are also widely represented in other parts of the Kelyana-Irokinda zone [18]-Kelyana riverhead (8 × 3.5 km) and

6 .
Recommended Approaches, Productivity Investigation Methods of Ore Mineralization due to the Revaluation of the Yubileyny Ore Field Industrial Prospects, Other Transbaikalia Noble-Metal Objects Most part of the industrial auriferous deposits in the Northern and Western Transbaikalia areas (Buryatia) were revealed, evaluated and explored in the 50 -80 years of the XX century.The works were mainly focused on expect-prospecting for vein gold-quartz and gold-sulfide-quartz mineralization types.At the same

Table 2 .
Ore-hosting rocks geochemical characteristics of the Yubileyny ore field dynamometamorphic complex.

Table 6 .
[1]ir shape is laminated, isometric, elongated, rarely irregular, from 0.05 -0.15 m to 0.2 -0.3 mm.It everywhere is replaced by pyrite and occurs in close accretion with chalcopyrite.Chalcopyrite is marked in the form of separate, irregular-shaped grains of 0.05 -0.1 mm in size and in accretions with pyrrhotite, pyrite.It also associates with magnetite and rutile.Single grains are not rare in micaceous-carbonate mass.Pyrrhotite is concentrated in the chlorite and micaceous mass, forming grains, unevenly distributed in the rock.Their shape is laminated, isometric, elongated, rarely irregular, from 0.05 -0.15 m to 0.2 -0.3 mm.It everywhere is replaced by pyrite and occurs in close accretion with chalcopyrite.Ores mineral composition of the Yubileyny field (partly used information[1]).