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.
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 (
Geological-economic calculations showed that the minimal industrial content of Au for deposits with veined quartz mineralization is 4 g/t [
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 [
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.
Ore deposits of the Yubileyny field (
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 (
The rocks location | Sample numbers | SiO2 | TiO2 | Al2O3 | Fe2O3 | FeO | MnO | MgO | CaO | Na2O | K2O | P2O5 |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Vendian-Riphean Kelyana-Irokinda | ||||||||||||
Irbo-Mladentsevsky ore zone | M-78 M-73 | 48.13 56.39 | 0.63 0.50 | 8.02 3.40 | 1.85 0.87 | 8.67 7.55 | 0.18 0.13 | 23.93 26.63 | 8.30 4.25 | 0.29 0.21 | 0.05 0.02 | 0.05 0.05 |
Yubileyny ore field | YUB-90 YUB-91 | 52.18 47.65 | 0.23 0.30 | 8.36 13.48 | 1.53 3.21 | 8.79 10.09 | 0.20 0.23 | 15.10 11.22 | 13.14 13.07 | 0.36 0.60 | 0.06 0.15 | 0.05 - |
Vendian-Riphean Gukit-Parama | ||||||||||||
Samokut ore zone | M-20 M-19/1 M-19/5 | 53.18 52.24 52.23 | 0.35 0.18 0.30 | 4.85 4.52 7.05 | 0.01 1.94 2.96 | 8.88 7.63 7.77 | 0.13 0.22 0.19 | 20.00 19.59 16.88 | 11.76 12.67 11.06 | 0.69 0.47 0.97 | 0.15 0.49 0.53 | - 0.05 0.06 |
Early Precambrian Olondo | ||||||||||||
48.02 49.40 48.71 47.98 | 0.39 0.30 0.45 0.83 | 7.12 7.86 8.83 8.76 | 11.24* 10.11* 11.14* 13.69* | 0.20 0.21 0.28 0.23 | 25.68 23.40 22.06 15.47 | 6.89 8.13 7.69 11.48 | 0.18 0.24 0.44 0.95 | 0.03 0.02 0.03 0.14 | 0.03 0.03 0.05 0.05 |
M―Mladentsevsky, YUB―Yubileyny.
Nyurundukan amphibolite strata of the North Baikal region [
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 (
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 (
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 which reaches 40% - 45%. Accessory minerals are represented by zircon, rutile, apatite, tourmaline (schorl), topaz. Rare scattered siderite and partly pyrite dissemination is observed.
Dynamoslate facies is represented by chlorite-Muscovite-albite-quartz, albite-quartz-Muscovite rocks. The dynamoslates appearance is associated with the development of late shift deformations and Kelyana-Irokinda shear zone formation in the final form. Dynamoslates compose the elongated bodies. In plan, they form a convergent and divergent band, delineating cataclasite and mylonites bodies. We can see a gradual transition of cataclasytized granites and porphyroclastic mylonites into dynamslates. For dynamoslates (attributed to them “beresites” and “listwenites”) the typomorphic parageneses are chlorite + sericite + quartz + albite; sericite + albite + quartz.
The rocks texture is usually banded. The bands width is not seldom contiguous, reaches up to 15 - 20 m. The structure is lepidogranoblastic one. Sericite is of two generations: 1) large-lamellar one associates with albite, coarsegrained veined quartz and chlorite; 2) small-lamellar one forms thin parallel bands. Chlorites are represented by ripidolite and pycnochlorites [
Based on the data analysis presented in
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. 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 (
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 (
3) rutile, met in dynamometamorphytes, contains V to 0.92 wt% and the chlorite of the “beresites” and “listwenites “ are enriched with Cr [
4) gold from quartz veins contains an admixture of Pt up to 0.13 wt% [
In the formation of Kelyana-Irokinda mineragenic zone tectonic structures three deformation stages [
Sample numbers | Rocks | Cr | V | Co | Pb | Zn | Sn | Sb | Nb | Ba | Sr | Rb | Zr | Y | La | Ce | Nd |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
YUB-91 YUB-90 YUB-97 YUB-6 YUB-10 YUB-16a YUB-18 YUB-15 YUB-1 YUB-2 YUB-55 24-04/6 YUB-44 YUB-67 | Basalt metakomatiite Metaboninite Cataclasit on granodiorite Milonit on diorite ??? “ ??? “ ??? ??? “ ??? “ ??? ??? “ ??? “ ??? ??? “ ??? “ ??? Dynamoslate on amphibolite ??? “ ??? “ ??? Dynamoslate with talc addition Dynamoslate on milonitized diorite ??? “ ??? “ ??? ??? “ ??? “ ??? | 54 590 49 41 <25 140 180 140 170 190 140 130 230 170 | 310 240 <80 <80 <80 140 140 130 170 180 140 140 200 180 | <50 <50 <50 <50 <50 <50 <50 <50 76 71 <50 <50 <50<50 | 19 16 170 180 21 - 72 36 70 - 22 77 - 15 | - 83 - - - - 63 78 92 - 65 - 43 66 | - 3.5 3.2 2.9 2.1 - 4.6 3.4 6.1 2.7 2.8 - 2.5 - | 4.3 3.7 7.3 3.6 2.4 - 23 - 20 3.6 3.5 11 3.3 2.7 | 6 11 11 6 7 10 17 9 8 9 12 12 11 6 | 280 640 450 490 540 540 880 540 470 760 640 380 670 600 | 190 120 57 230 180 160 101 236 170 256 130 170 79 190 | 72 98 150 120 84 120 170 120 93 160 140 176 136 98 | 210 140 200 150 120 240 285 200 154 210 160 200 250 210 | 53 21 35 41 30 29 48 32 33 27 28 37 36 34 | 30 11 22 19 - 24 46 17 21 14 24 12 28 14 | 64 32 55 50 26 53 92 48 51 45 57 36 68 45 | 23 - 22 - - 26 48 ? 19 - 25 - 20 - |
Note: Ni 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.
Sample numbers | Rock | Ag | Au | Pt | Pd |
---|---|---|---|---|---|
YUB-91 YUB-90 YUB-97 YUB-6 YUB-10 YUB-16a YUB-18 YUB-15 YUB-1 YUB-2 YUB-55 24-04/6 YUB-44 YUB-67 | Basalt metakomatiite Metaboninite Cataclasyt on granodiorite Milonit on diorite ??? “ ??? “ ??? ??? “ ??? “ ??? ??? “ ??? “ ??? ____”____”___ Dynamoslate on amphibolite ??? “ ??? “ ??? Dynamoslate with talc admixture Dynamoslate on milonitized diorite ??? “ ??? “ ??? ??? “ ??? “ ??? | 1.0 (0.30) 1.2 (0.33) <1.0 1.0 1.0 1.3 1.3 1.6 2.6 1.3 2.2 1.2 1.8 <1.0 | 10.0 (27) <10 (0.23) 10.0 <10 15.0 <10 <10 <10 23.0 47.0 83.0 <10 20.0 13.0 | 4.0 (412) 9.0 (72) <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 | 32.0 17.5 0.2 <0.2 <0.2 1.5 1.0 1.0 1.0 1.0 1.5 1.0 1.5 1.5 |
Note: Ag―g/t; other elements―mg/t; in brackets―contents according to the microprobinng neutron- activation analysis (analyst G. M. Kolesov, Institute of Geochemistry, RAS). GIN SB RAS―Geological Institute, Siberian Branch, Russia Academy of Sciences. YUB―Yubileyny field
№ | Sample number | Cr | V | Co |
---|---|---|---|---|
1 | 24-04/4 | 240 | 210 | 79 |
2 | YUB-88 | 75 | <80 | <50 |
3 | YUB-92 | <25 | <80 | <50 |
4 | YUB-100 | 28 | <80 | <50 |
5 | YUB-101 | 120 | <80 | <50 |
6 | YUB-105 | 120 | 85 | <50 |
7 | YUB-108 | 220 | 210 | <50 |
The elements oxides | The ore-bearing dynamoslates of Yubileyny field | Olondo greenstone belt metakomatiites [ | |||||||
---|---|---|---|---|---|---|---|---|---|
SiO2 | 52.89 | 49.78 | 52.28 | 51.83 | 51.03 | 49.28 | 47.90 | 52.1 | 51.32 |
TiO2 | ? | 0.42 | ? | ? | 0.49 | 0.276 | 0.274 | 0.218 | 0.148 |
Al2O3 | 3.97 | 7.49 | 5.52 | 6.20 | 8.00 | 8.89 | 9.75 | 6.88 | 7.35 |
Cr2O3 | 0.46 | 0.47 | 0.49 | 0.40 | ? | 0.366 | 0.383 | 0.308 | 0.376 |
FeO | 11.32 | 12.83 | 11.45 | 11.85 | 13.32 | 9.32 | 9.80 | 10.51 | 9.17 |
MgO | 16.29 | 14.42 | 15.99 | 15.28 | 14.86 | 16.47 | 15.53 | 18.13 | 17.18 |
CaO | 12.60 | 12.73 | 12.76 | 13.04 | 13.16 | 11.85 | 11.90 | 9.04 | 11.97 |
MnO | ? | ? | ? | ? | ? | 0.143 | 0.121 | 0.222 | 0.143 |
Na2O | ? | 0.61 | 0.49 | ? | ? | 1.13 | 1.23 | 0.837 | 0.836 |
Total | 97.53 | 98.75 | 98.98 | 98.60 | 100.86 | 97.87 | 97.09 | 98.31 | 98.64 |
The analyses were performed on the electron microscope LEO-1430VP by N.C. Karmanov.
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: amphibolites-cataclasites, mylonites-dynamoslates, ore vein quartz [
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
The 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 P2+P3 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 (
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 (
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.
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.
Morphostructural mineralization type | Main ore minerals | Typical secondary and accessory ore minerals |
---|---|---|
Veinlet-veined | Pyrite, Galena, sphalerite, chalcopyrite | Native Au, Ag, Cu, Bi, Sb, Te, Pt?, Pd?, Ru (Os, Jr), altait―PbTe, petzite―Ag3AuTe2, hessite―Ag2Te, calaverite―AuTe2, coloradoite―HgTe, krennerich―(Au,Ag)Te2, Silvana―AgAuTe4, tellurobismuthite―Bi2Te3, impressit―AgTe, vulcanite―CuTe, Riccardi―Cu3Te2, melonit―NiTe2, clausthalite―PbSe, umangite―Cu3Se2, magnetite, hematite, hubnerite, ilmenite, rutile, tetrahedrite, tetradymite, marcasite, molybdenite, pentlandite, pyrrhotite, nagyagite?Pb5Au(Te, Sb)4S5-8, arsenopyrite |
Disseminated | Pyrite | Pentlandite, pyrrhotite, chalcopyrite, sphalerite, Galena, marcasite, ilmenite, magnetite, hematite, rutile, native Au, Ag, Fe, Pt?, Ru (Os, Jr), Pd? |
Sample numbers | Au | Morphostructural mineralization type |
---|---|---|
24-04 YUB-84 YUB-101 24-04/2 YUB-57 24-04/5 YUB-47 | >500 >500 50 15 70 3.0 15 | Quartz-vein ??? “ ??? “ ??? ??? “ ??? “ ??? ??? “ ??? “ ??? Veined-quartz in dynamoslates Disseminated in dynamoslates ??? “ ??? “ ??? |
GIN SB RAS―Geological Institute, Siberian Branch, Russian Academy of Sciences. YUB―Yubileyny field.
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 (V2O5 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 (
Sample numbers | Ni | Cu | Zn | Pb | Sb | Ag | Au | Pt | Pd | Os | Jr | Ru |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Quartz-vein type | ||||||||||||
YUB-92 24-04 YUB-84* YUB-86 YUB-101 24-04/1 YUB-108 YUB-88 24-04/2 24-04/4 | 0.0003 0.0003 0.0004 0.0010 n.d 0.0003 n.d n.d 0.0010 n.d | 3.2 1.91 1.56 0.274 0.156 0.123 0.533 0.040 0.022 0.012 | 3.61 2.19 1.51 2.67 - 0.051 0.957 0.012 0.018 0.012 | 2.28 2.28 1.90 8.10 0.061 0.183 0.521 0.026 0.038 0.0017 | 0.052 11.0 9.5 0.007 0.004 0.410 0.047 0.190 0.130 0.050 | 475 454.7 254.6 540.04 8.44 26.0 80.0 14.2 6.2 1.4 | 12.8 35.9 120.0 5.7 4.8 13.2 >1.0 >1.0 0.9 13 | 0.948 - - 1.06 4.56 - - - - - | 17.5 <0.2 0.2 1.0 2.0 0.2 2.0 1.0 1.0 1.0 | 3.38 n.d 5890 3.16 - n.d n.d n.d n.d n.d | 4.95 n.d 7800 4.12 0.58 n.d d.n n.d n.d n.d | 46.2 n.d 146000 33.3 30.3 n.d n.d n.d n.d n.d |
Disseminated sulfide type | ||||||||||||
YUB-47 YUB-55 YUB-44 YUB-102 YUB-50 YUB-9 YUB-13 YUB-11 | 0.228 n.d n.d n.d 0.074 0.227 0.069 0.187 | 0.086 n.d n.d - - 0.006 0.016 - | ? n.d n.d 0.0063 0.0084 0.0051 0.0063 0.0037 | 0.077 n.d n.d 0.0072 0.0076 - 0.0025 - | 0.001 n.d - - 0.0068 - - 0.00035 | 20.0 27.6 0.21 0.72 2.8 n.d 1.2 n.d | 0.316 1.36 0.0477 0.109 0.038 n.d n.d n.d | n.d 0.196 0.460 0.668 - n.d - n.d | n.d 1.5 1.5 - 1.0 n.d 1.0 n.d | n.d 1.84 1.71 1.68 n.d n.d n.d n.d | n.d 1.31 0.73 2.02 n.d n.d n.d n.d | n.d 16.6 12.5 17.4 n.d n.d n.d n.d |
Note. Concentrations of: Ni, Cu, Zn, Pb and Sb―in wt%; Ag, Au and Pt―in g/t, other elements―in mg/t; n.d―content was not determined, “-”―not found, *―vein sulfide rim 70. YUB―Yubileyny field. GIN SB RAS―Geological Institute, Siberian Branch, Russian Academy of Sciences.
in sulfide rims, the most possible presence form of these platinoids is as native ruthenium with an admixture of Os and Jr. Mineralogical analysis of the YUB-84 (vein 70) sample sulfide graviconcentrate showed the following ore minerals species composition: sphalerite (34%), faded ore (30%), Galena (21%), pyrite (15%), chalcopyrite (rare signs). Zn contents in quartz veins reaches 3.6 wt%, Pb to 8.1 wt%, Sb up to 11 wt%. Disseminated sulfide zones contain significantly less of Au, Ag, platinoids (up to 0.69 g/t), polymetals, but are enriched with Ni due to the presence of pentlandite, nickel-containing pyrite and pyrrhotite. They can be considered as the complex nickel-noble metal ores.
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 (
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 time, the evaluation, deposits exploration regardless of the gold coarseness and its distribution nature, was carried out by a single method of trenching sampling. These approaches have largely survived to this day. However, the vein type of industrial mineralization potential was almost exhausted, and attempts of ore bodies prospecting and assessment with veined-disseminated gold-sulfide-quartz and disseminated gold-sulfide mineralization types, which are associated worldwide with large-capacity reserves and relatively poor in content (2 - 4 g/t) deposits, were mostly ineffective due to the trenching sampling application as the main method of ore bodies delineation, of reserves evaluation.
Due to the insufficient effectiveness of traditional trenching sampling method in the prospects, evaluation and exploration of ore bodies with large ash nugget and extremely non-uniform its distribution, many of the Kelyana-Irokinda objects have been undervalued and even discredited as perspective ones (Yubileyny, Irbo, Irokinda ore fields; occurrences―Samokut, Osinovy, Upper-Samokut and others, Selenga-Vitim (Tsipikan, Gorbilok ore zones) greenstone belts of the Vendian-Riphean age [
Ignored and not studied a large group of ore fields tectonic structures complex in the construction, ore zones such as “zone of tectonic and autoclastic mélange with their varieties: coarse-block, middle-block, small-block, lenticular-laminated”, “losange zones (duplex) of different extent”, “zones of multi-seam, low amplitude thrusts” that are widespread in many auriferous areas of Transbaikalia [
The above mentioned types of charriage-thrust structures are proper to a new formartional type of gold mineralization allocated by A. D. Shcheglov, which he called “zones of mylonitization and foliation” [
When studying the Yubileyny field ore zones productivity, it is necessary not to use trenching sampling as the main ore zones evaluation method, replacing it by small-capacity bulk sampling, with the following results certification with single large-capacity bulk samples.
We recommend to reevaluate the Yubileyny ore field industrial (commercial) prospects, changing a strategy, prospecting technique and ore bodies evaluation. There are all prerequisites for the detection of multicomponent ores large-tonnage deposits, cost-effective for an open pit mining.
The most important problem is the available forms detection of “invisible” PEG and partially Au. Perhaps a significant part of this difficulty to enrich variety of ore mineralization is represented by fine nanominerals, cluster, colloidal forms, which require the development of new technological enrichment schemes, different from traditional ones.
Yubileyny ore field considered as example in the article allows us to offer some relevant measures to improve the economic efficiency of the mining industry in Buryatia, namely:
1) To change the strategy of predictive-metallogenic, expect-prospecting and exploration works for gold with a focus on the identification of large reserves (≥100 tonnes), suitable for open pit mining with polycomponent ores localized in the Vendian-Riphean greenstone belts and confined with dynamometamorphic complexes developing on the rocks of the picrite-komatiite-tholeiite series. To date, according to our preliminary estimates, in addition to the Yubileyny field, the primary objects of the prospecting stage, reserves of which are determined (up to depth of quarry development―50 m) at least of 150 - 200 t for each one, are: Lower Samokut and Tsipikan zones;
2) When carrying out expect-prospecting and prospect-evaluating work it is necessary to use a cheap express mapping mineral-geochemical method of productive zones and bodies [
3) To put in practice of expect-prospecting and exploration work the more reliable bulk sampling method instead of ineffective trenching sampling. To study large-capacity bulk ore samples, it is necessary to have a special small enrichment factory on the territory of Buryatia, the corresponding modular units, to use the methodological developments of TsNIGRI, Magadan, Chita and Irkutsk geologists.
The authors declare no conflicts of interest regarding the publication of this paper.
Yalovik, L.I. and Tatarinov, A.V. (2019) Characterization of Yubileyny Field Ore Potential Based on New Structure-Substance Information. Geomaterials, 9, 1-16. https://doi.org/10.4236/gm.2019.91001