History of the Aktyuz Ore Field

Geological opinion translated from Russian

This report is long out of date, and should not be relied on for resource calculations. “A qualified person has not done sufficient work to classify the historical estimate as current mineral resources, Stans Energy Corp. is not treating the historical estimate as current mineral resources and the historical estimate should not be relied upon.” Dr Gennady Savchenko QP for Stans Energy Corp., and managing Director for Stans Energy KG was Deputy Chief, Department of Geology & Investment, Kyrgyz State Geology & Mineral Resources Agency; member of Kyrgyz State Mineral Reserves Committee.

Inv. № 0444. Funds of Institute of Geology
of National Academy of Sciences
of the Kyrgyz Republic.

Kharchenko A.D., Khokhlov, A. T., Kim, V.F., Komissarov V.A.

FEATURES OF GEOLOGICAL STRUCTURE, WORKING-OFF AND PROSPECTS OF STOCKS INTENSIFYING IN AKTYUZ ORE FIELD.

I. Brief description of Aktyuz ore field

The peculiar polymetallic-rare-earth deposits, presented by tubular bodies of altered granophyres, converted into secondary quartzites and quartz-chlorite-sericite rocks have been well-known in Central Asia for a long time. All of these tubular bodies are located within a single Aktyuz ore field on the continuation of alaskite granites massif of Upper Permian age.

For many years Aktyuz ore field have been studied by A.V. Peck, F. Sh. Radjabov, N. Tikhomirov, L.Z. Shavshukova, V.A. Nevsky, P.S. Kozlova, V.A. Nikolaev, S.P. White, S.D. Turov, V.P. Turchinskiy, V.F. Kim, V. Pivovarov, F.I. Borisov, and many others.

According to these researches the geological structure of ore field can be briefly summarized as follows: containing rocks are presented by Precambrian metamorphic rocks, forming complicated anticline fold of northeast strike, the axis of which is immersed to southwesterly direction. The core of the fold is composed of quartz-plagioclase gneiss, and the wings – by green amphibole shales.

Aktyuz ore field that extends for 5 km, is bounded on the south-east and north-west by two regional fractures: northeast (southern fault) and sublatitudinal (northern fault), these faults form a kind of wedge in the south-western part of which massif of alaskite granites is located. This wedge-shaped block is limited by two faults and divided by a series of tectonic disturbances of sublatitudinal, submeridional, north-eastern and north-west directions.

Alaskite granites massif, exposed in the southwestern part of the ore field is also limited by the northern and southern faults, beyond which it does not go, and in turn, it is divided into a series of zones of sublatitudinal ways in which some parts of it are relatively shifted one to another.

Massif property reaches 13 km 2. According to structural drilling information, massif of hollow is immerged (approximately at 16 °) north-east, with the massif roof being very complex and characterized by number of blind domes, appearing at 0,9-1,2 km from each other. Above these domes tubular bodies of granophyres are located, they can be often vertically traced at 300-800 meters.

Investigation of the tubular body distribution within Aktyuz ore field was worked-out by number of researchers whose views on the formation of tubular bodies were very diverse.

During the years 1930-40, when Kuperlisai, Kutessay I, Aktyuz deposits and ore manifestations located along the amphibole shale contacted with gneiss and had isometric shape in plan and almost vertical angles of incidence, were identified, the first explorers A. B. Peck and F. Sh. Radjabov made a suggestion of the possibility of breccias initiation as a result of schistovity movement on the planes, whereby twist and torsion of rocks with their subsequent fragmentation to the breccia were happened.

In 1940-50, as a result of prospecting and exploration two tubular bodies: Kutessay II deposit and Andzhidga ore manifestation were revealed. During this period forms of ore bodies and their structural elements were studied in details, what allowed researchers of this period to change hypothesis of tubular bodies formation. So N.D. Tikhomirov suggested that nodes of intersection and pairing of tectonic faults of very different directions occupy an important place in formation of tubular bodies.

In the period of 1950-65 exploration of field deeper horizons took place in order to detect “blind” ore bodies, as a result of these works two blind tubular bodies have been identified. They are: northern ore body of Kutessay II deposit and northern ore body of Aktyuz deposit. In addition, it was found that the subalkalic leucocratic granite massif submerges in the north-east at an angle of 16 °, all the ore bodies that are of commercial significance are located in North member of amphibole shale, and in the southern member of amphibole shale as a result of intense fracturing, industrial concentration of polymetallic and rare earth elements, except for tin and beryllium can not be identified. All known tubular bodies are located in the watershed areas, which indicate the predominance of the vertical forces action over the introduction of the granites. In this process, the northern member of green amphibole shale has been deformed into a number of blocks of a certain system of fractures. Subsequently, the fractures were filled with brecciation edjoining rock and subalkaline leucocratic granites. And the upper zone of compression and fragmentation have been prone to erosion and cavity formation. In addition, the parts of granite or granophyre introduction were subjected to more intense silicification, cornification, skarn.

It was found that almost all of tubular bodies have southwest declination, for a total immersion of the fault structure, within the known deposits it is to the north-east, and it varies with depth to the north or north-west.

II. The history of deposit development in Aktyuz ore field and the immediate tasks on complex field exhaustion of Kutessay I and Kutessay II deposits

In the process of Aktyuz deposit processing from 1942 to 1966, 2,620.7 thousand tones of ore, 78,563 tones of lead, 37,252 tones of zinc, 2751 tones of tin, 3,820 tones of sum of rare earth sesquioxides and 2100 tones of molybdenum were produced.

During the ore processing at Aktyuz concentration plant for the entire period of Aktyuz deposit processing the following information has been learned:

  1. Lead metal- 57,380 tones;
  2. Tin metal – 149,4 tones;
  3. Zinc metal – 1744.8 tones;
  4. Molybdenum metal- 388.9 tones;
  5. Silver metal – 13.417 tones;
  6. Copper metal – 769.6 tones;
  7. Gold metal- 5.344 tones.

The whole production was sold at 30 million 848 thousand rubles without regard to the rare-earth products, processing of which began in 1961. So in 1961 the extraction of rare earths was 0,6% in the concentrate with the content of the amount of rare earth elements oxides of 16,45%, and in the same year, in cooperation with members of Giredmet Institute installation of Hydrometallurgical stripping of rare earth concentrates was settled. During two months 8,4 tones of concentrate with the 20,1% content of yttrium were processed. 409 kg of rare earth hydroxides with yttrium content of 20,59% were received. Extraction was 49.8%.

Kuttesai II deposit was discovered in 1943 by N.D. Tikhomirov and F. Sh. Radjabov. During the initial period exploration work was carried out by “Sredaztcvetmetrazvedka” trust, and recently by the Office of Geology of the Kirghiz SSR and Aktyuz mine of Kyrgyz Mining and Metallurgical Combine. Totally three reserve calculations were made there: the first – on I/I-I947, the second as stock on I/I-I95I year. This calculation was performed in two contours: lead contour with lead cut-off grade of 1% and thorium ore contour with cut-off grade of thorium dioxide of 0,02%, the third reserve estimate was made and approved by the SRC at 1/1-1959 in the lead contour with cut-off grade in the content of 0,7% and in the rare-earth contour with cut-off grade of rare-earth sesquioxides amount of 0.1%.

In the process of Kutessay II deposit working out from I960 till I/I-I976, 2087 thousand tones of ore, 21099 tones of lead, 167 tones of molybdenum, 17.276 tones of silver and 25.065 tones of bismuth were produced and recovered.

With the design capacity of 250 thousand tones of ore per year, the company is provided with stocks of all categories during 75 years. The lead content in the remaining ore is very low- 0.30%, but this element should be extracted as lead concentrate while working out the lower horizons containing more than 1 kg of silver per 1 tone of concentrate, or 15 tones of silver can be extracted from the remaining reserves; in addition, lead concentrate would contain 0.3% of bismuth, or for the entire period of working out 44 tones of bismuth can be obtained.

Special mention should be given to the zirconium extraction from hafnium of Kutessay deposit ore. With the design capacity of 250 tones per year, with an average content of zirconium dioxide in the processed ore being 0.50%, with extraction: the enrichment of 50% and metallurgy of 50% 312 tones of zirconium oxide can be annually obtained.

Zirconium dioxide, purified of hafnium has a price of 10 rubles per 1 kg.
Annual sale of zirconium can amount:
10 rub. X 312000 kg – 3 million 120 thousand rubles.

The average content of hafnium dioxide in the mineral is 2%, so each year up to 10 tons of hafnium dioxide can be metallurgically obtained from ore. Priced at 1,100 rubles per 1 kg of hafnium oxide annual selling could be:
1100 rub. X 10120 kg = 11 million rubles.

Thus, the overall selling of zirconium and hafnium makes up 14 million 120 thousand rubles per year.
Recoverable value of zirconium and hafnium from the remaining ore of Kutessay deposit amount:
14 million 120 thousand rubles x 70 years = 988.4 million rubles.

In addition, please note that the extraction of zirconium from ores of Kutessay field increases and the extraction of rare earth elements, to an average up to 14%, is bound to zirconium minerals and is not currently opened in the metallurgical.

At present, all 14 lanthanide elements and yttrium are extracted from rare earth concentrates obtained with metallurgical from ores of Kutessay II.

While stripping and explorative prospecting works on the southwestern flank of Kutessay I deposit (2443 m point) zone of molybdenum mineralization in gneiss metasomatites with capacity of 25 m along the strike has been traced for 60 m, this zone has not been included into rare-earth contour of Kutessay I deposit. Molybdenum ore in the amount of 358 thousand tones, 179 tones of molybdenum metal can be worked out incidentally with rare-earth ore of Kutessay I deposit.

It should be noted that with the production of stripping works at Kutessay open pit 460 tones of beryllium ore of Kalesay deposit can be worked out. Currently, beryllium ore in the amount of 53 thousand tones is stocked in a special pile of beryllium ore.  III. Prospects for expanding of the mineral resource base in Aktyuz ore field In Aktyuz ore field four deposits (Aktyuz, Kutessay, Kuperlisay, Kalesay) and sets of ore manifestations of different raw materials are currently known.

Exploration work carried out by the Office of Geology of the Kirghiz SSR in Aktyuz ore field for a long time have been suspended in 1969 because of negative results. In 1972 these works were resumed in accordance with the directives of the ninth five-year plan to increase exploration and prospecting for non-ferrous and rare metals, especially in areas of existing mining enterprises, as the most economically advantageous for their industrial development and at the request Aktyuz ore enterprise .

In the first year of exploration works renewal identified a number of interesting manifestations of bismuth on the flanks of the Kuperlisai deposit were identified by Kichi-Kemin party of the Office of Geology of the Kyrgyz SSR. According to the direction of the Office of Geology of the Kyrgyz SSR results of exploration were found negative. Therefore, exploration of Aktyuz ore field was suspended in 1975.
After the works of 1970-73 V.P. Turchinsky and others made up an explanatory note to the predictive map of 1:10000 scale of Aktyuz ore field. It emphasizes that large and systematic work on investigation of geological structure, characteristics of the ore controls for the various types of deposits and the effectiveness of methods for assessing at the stage of exploration is required. “Only in the process of such work (and not suddenly) robust search features and effective methods of evaluation can be developed”(Turchinsky V.P., 1973).

Systematic exploration is required to maintain Aktyuz mining and processing enterprise, continuing his life and capacity of mineral resources. In addition, it is necessary to discover new deposit types with new kinds of mineral raw materials.

However, due to the fact that Aktyuz ore field is precisely investigated from the earth’s surface, the discovery of new deposits is mainly associated with the identification of hidden (blind) ore bodies and deposits. Therefore, nowadays all the exploration works must be directed at revealing the hidden, deep-lying ore bodies.

The question is as follows: can we expect discovery of new blind ore bodies and deposits in the ore field? This question can be answered affirmatively, as with the exploration of the lower horizon (2353 m) of Kutessay II deposit blind Northern Stock with industrial containing of rare earths, molybdenum, lead and other elements was identified. In November 1975, with penetration to the exploratory adit No. 27, given on the 2213 m horizon, the presence of mineralization at deeper depths was confirmed.

Favorable sites for detection of blind ore bodies with industrial contents of rare earths, tin, zirconium, hafnium, tantalum, niobium, lead, zinc, bismuth and silver are the north-western and south-eastern flanks of the lower horizons of Kutessay II deposit. The watershed area, located between Kuperlisai and Kutessay gullies is the primary site for exploration and evaluation work.

Kuperlisai deposit is explored for thorium. During the period of exploration (1939-41) field testing of the content of other elements, including REE was not carried out.

Investigations carried out by V.F. Kim and V.A. Komissarov in 1974-75 found that the northern endo-and exocontact of greisen and greisenized rocks of granites with green amphibole shale contain the amount of rare earths up to 0.5%.

In the area of the tubular breccia body development, cemented by albite, content of total rare earths achieves 1.53%. In the north-eastern part of the massif, where the granite is bedded under gneisses near the contact with the green amphibole shale, the increased concentration of rare earth elements of 0.12-0.14% is also noted (adit number 17).

Kutessay III deposit that is a flanking continuation of Kutessay II deposit, on the one hand, and Kuperlisai – on the other, is located at 150 meters to the north-east from Kuperlisai deposit. Kutessay III deposit evaluation, conducted by geologists of Aktyuz ore enterprise showed that lead, molybdenum and thorium mineralization in the industrial concentrations is observed in thin quartz veins, lenses and nests with power of 0.5-1.5 m.
In addition, rare-earth ore body with the length of 300 m is identified at Kutessay III deposit. Its power varies from 22 to 50 meters, medium – 40 m. The content of total rare earth sesquioxides varies from 0.10% to 0.25%. Preliminary stock estimation of rare earth oxides amount to a depth of 250 m showed that they are about 1600 tons.

All this allows us to recommend the north-eastern section of Kuperlisai deposit and its extension to immersion of subalkalic leucocratic granites in the direction of Kutessay III field exploration and re-estimating works.

During the initial period of Kutessay II field exploration the constant presence of bismuth from 0.001 to 0.017% was noted in the ores. N.D. Tikhomirov connects the presence of bismuth with galena. Relation was established as follows: the reduction of lead content with depth increases the content of bismuth and silver. The same dependence is set to Aktyuz field. If in the upper levels of ore pieces with lead containing 45-50% bismuth contained 0.03%, for the lower horizons, with the same lead content in the ore content of bismuth is doubled.

Within Aktyuz ore field the highest concentration of bismuth is installed near the massif of alaskite granites, where the veins with the industrial content of bismuth are settled. Within “New” Kutessay ore manifestation with lead content of 50% bismuth content of 0.18% is set in ore piece. For the upper horizons of Kutessay II deposit, this value is 0.15%, while for Aktyuz deposit it is 0.03%, i.e. bismuth content decreases with moving from magma chamber.

Based on the analysis of the complex of geological, magmatic, structural-tectonic, mineralogical and geochemical, geophysical and geomorphological materials members of the Institute of Geology of the Academy of Sciences of the Kyrgyz SSR (1975, Kim V.F., Kharchenko, A.D., Komissarov V.A. .) currently compiled a prognostic map of Aktyuz ore field for the search of “blind” ore bodies.

The primary site for exploration at the incremental reserves of rare earths, yttrium, zirconium, hafnium, tantalum, niobium, bismuth, silver and other components are lower horizons of Kutessay I and II, Aktyuz, Kalesay and Kuperlisay deposits.

Tegerek area is recommended for searching for ore bodies and deposits.

In 1973 on the left bank of Andzhilga-Sai 3 geochemical anomalies were determined (Kim, V.F., etc.). The second anomaly is nominated for exploration as the most prospective.

Currently Aktyuz ore field accounts for about 50 identified anomalies. 36 of them are mapped by N.I. Doroshenko, Erokhov, V.N. Turchinskiy, V.F. Kim. All of them are precisely described in the reports. Several of these anomalies are the prime targets for further exploration and evaluation work.

In general, the possibility of expanding of Aktyuz Ore enterprise mineral resource base is sufficiently large. It can be increased at the expense of rare earth, thorium and molybdenum ore deposits, located between Kuperlisay – Andzhilga-Sai rivers.

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