Genetic Types Of Rare Mineral Gold Of Western Uzbekistan (Southern Tien-Shan)

The work describes the genetic types and conditions for the localization of mineralization - individual deposits and ore occurrences. Also, the indicated mineralized zones, the conditions of occurrence of the mineralization, the geological-structural position and the peculiarities of the host complexes. Descriptions of promising tungsten, tin ore, polymetallic, mercury and other ore zones, which serve as a reserve in expanding the resource base in the Republic, are given. Tungsten, tin ore, and mercury mineralizations are characterized in somewhat more detail, since the latter in the region under study is often spatially associated with gold and forms mercury-antimony-polymetallic mineralization.


INTRODUCTION
At present, Western Uzbekistan is considered one of the most promising for gold, silver, tungsten, tin, mercury, antimony, lead-zinc, uranium and other minerals in the Central Asian ore province. As a result of the work of a large team of geologists -production (Goskomgeology, Navoi and Almalyk mining and metallurgical combinat (MMC)) and   [1,5,8,9,12,14,15].
The object of the study is the territory of the part of the Southern Tien Shan, which is located in Western Uzbekistan with deposits and ore occurrences of gold and rare-metal mineralization (Fig. 1).

MATERIALS AND METHOD
Questions of geology, conditions of formation and patterns of distribution of mineralization were covered in the works of many researchers [2, 4, 6, 11]. Therefore, the article describes only the genetic types and conditions for the localization of mineralization -individual deposits and ore occurrences.
Among the known ore occurrences of the region, gold, tungsten, tin ore, mercury, antimony and rare-metal deposits are of the greatest practical interest.
Below, we will dwell in more detail on the characteristics of the manifestations of tungsten mineralization, since the latter in the region under study is often spatially associated with gold ore and especially for forecasting with mercury and mercuryantimony-polymetallic mineralization. With their genetic link to tungsten. A similar mineral association is found in the Caucasus, Transbaikalia, in the southern provinces of China and other regions. A certain paragenetic relationship is also noted between tin ore and mercury-antimony mineralization.
Tungsten mineralization. Uzbekistan occupied one of the leading places in the production of tungsten ores in the 70s of the XX century. Industrial tungsten deposits are concentrated within Western Uzbekistan (Ingichka, Lyangar, Koytash, Yakhton, Karatyube, etc.), among which many deposits are fully or partially worked out. Within the study area, significant accumulations of tungsten mineralization are concentrated in skarn zones and ore formation is associated with skarn formation. Skarn-ore deposits and ore occurrences are represented by limestone and, in small quantities, magnesian formations.
A much smaller scale than Ingichka, Koytash, Lyangar, Yakhton is the Chuyunskoye deposit, as well as industrial and related objects with tungsten trioxide content are noted in some areas of contact skarn bodies. In the ore occurrences of Shar-Shara, Rabanjan Changalli, Beshtal, Mulla-Burkhan, Sarutau, Sautbai, Devona-say, chalcopyrite plays the leading role of ore minerals. Here, in the skarnated hornfels, in some places there are high gold contents, increased concentrations of silver and some other elements.
Thus, the above ore occurrences, according to the conditions of the occurrence of mineralization, geological and structural position, and the peculiarities of the host complexes, together form promising tungsten ore zones, which serve as a reserve in expanding the raw material base of tungsten in the Republic. Apomagnesian -calcareous skarns, which formed due to the transformation of magnesian skarns of the magmatic stage, are represented by their mineral composition: scheelite, galena, sphalerite, arsenopyrite, cassiterite, tellite, bismuthine, pyrrhotite, etc. They contain trace elements: silver in galena n / t, in sphalerite n 10g / t and bismuth and tin are found slightly in hundredths of a percent. When studying the peculiarities of the mineral composition of the apomagnesian-calcareous skarns of the Ingichka ore field, their connection with the Kattasaykiy fault was revealed, at the southern end of which the skarn-tin-polymetallic ore occurrences Kaltasai and Kizkurgan are located, which are similar in composition.
A rather wide complex of ore minerals (scheelite, molybdenite, arsenopyrite, sphalerite, galena, magnetite, etc.) is established in the skarns of Tyma, however, at this stage, none of them forms industrial accumulations.
Conditioned contents of tungsten trioxide and other metals are recorded in separate areas of the Kyzkurgan, Kaltasaya and Zirabulak skarn bodies and other ore occurrences.
All skarn bodies of the area are spatially associated with granitoid intrusions of the Upper Carboniferous -Lower Permian (C3-P1) and are localized either in their direct contact with carbonate host rocks or in the exocontact zone.
The most favorable environment for the formation of scheelite-bearing skarns is limestone and, in particular, dolomite limestone.
In the formation of skarn bodies, two types of structures should be distinguished: ore-mixing structures, with which the placement of skarn is directly related and ore-bearing solutions along which ore-bearing solutions come from the centers of their origin to the places of localization.
Thus, the formation of scheelite-bearing skarns is determined by combinations of magmatic, lithological, and structural factors and the role of host rocks in the location of mineralization.

Tin mineralization
In contrast to tungsten mineralization, tin is found in the region in various mineral forms. Only a few tin ore deposits are known, but tin is sometimes present in noticeable quantities in tungsten deposits and forms a general broad scattering background in various types of intrusive as well as postmagmatic altered rocks. Thus, at the Changalli deposit, greisenized granodiorites accompanied in places by albitized Ingichke granitoids were found to have high scheelite concentrations.
In the aisles of the region, greisen, pegmatite genetic types of ores and associated tin ore rare-metal, rare-earth, etc., mineralizations are poorly studied, in connection with which it is necessary to carry out revision assessment work on the above-mentioned minerals. The main ore-bearing and ore-controlling structures in the aforementioned ore occurrences and deposits in all cases are small and large faults. Thus, within the described region, according to the data of previous researchers and according to the results of our work, the following tin ore formations can be distinguished: pegmatite, cassiteritequartz, carbonate-cassiterite formation. This formation includes deposits (Changaly, Karnab, Lopas, Altyn-Kazgan and Kermene), as well as a number of small occurrences associated with quartz veins.
Lead -antimony mineralization. A typical representative of the deposits of this ore formation is Keltasayskoe in the Zirabulak mountains. It gravitates towards the southwestern part of the Zirabulak intrusive massif, composed of felsic rocks. Directly orebearing rocks -altered (skarnated, silicified) dolomites, limestones and shales.
Ore bodies are small veins confined to steeply dipping fractures that develop in the exocontact zone of stocks and dikes.
Primary ore minerals were, apparently, complex sulfasalts: exploration workings uncovered only the bodies of massive oxidized ores containing high amounts of lead, antimony, zinc, copper, tungsten trioxide, tin and silver.
Deposits of lead-antimony ores from hydrothermal solutions occurred at the junctions of ruptures with gently dipping cracks in the soda part of the anticlinal structure.

Mercury mineralization
A number of ore occurrences of cinnabar (Dzhilga, Kazanbulak, Vostok-I, Dalniy, Karasu, Pastkucha, Konchoch, Yubushkushkoye , Myk, Dzhalgiz, Kurgancha, Altyaul including four mineralized points that make up a single Altyaul ore field). The main structural element of the latter is the Altyaul anticline. The strike of the fold is northwestern, close to latitudinal. This structure is complicated by folding of smaller orders.
The most favorable ore-bearing rocks are dolomites, dolomitic limestones and limestones [13,16,17]. Much less mercury mineralization is found in shales and sandstones. Hydrothermal changes within the ore field affected all varieties of ore-hosting rocks.

CONCLUSION
In conclusion, it should be noted that most of the deposits and ore occurrences known within Western Uzbekistan seem to be very promising and, of course, deserve further comprehensive research and geological exploration.