URANIUM EXPLORATION Historical review

Uranium exploration in Mongolia started immediately after World War II with investigations of other various mineral deposits. During 1945–1960, number of occurrences of uranium were discovered in the deposits of brown coal in the Eastern Mongolia.

Between 1970 and 1990 under the bilateral government agreement of the Mongolian Peoples Republic and the USSR specialized geological works were conducted by Geological Reconnaissance Expedition of Ministry of Geology USSR During that period full airborne gamma-spectrometric surveys of scale 1:25,000–1:50,000 on the territory of the country over 420,000 sq.km. or 27% of the territory; of scale 1:200,000 over 450,000 sq.km. or 28% of the territory and of scale 1:1,000,000 over 224,000 sq.km. or 14% of Mongolian Altai and Hangai mountain and Gobi desert region were conducted. The territory along the border with People's Republic of China and Central Mongolian mountain area or 30% of the territory was left out of these surveys.

Metallogenical investigation of scale 1:500,000 over 500,000 sq.km area and more detailed geological exploration of scale 1:200,000–1:50,000 over 50,000 sq.km area of territory of Mongolia were completed. All these works included 2,684,000 m surface drilling, 3,179,000 cube.m. surface trenching and 20,800 m underground exploration.

Based on results of these explorations, the territory of Mongolia was classified into four uranium bearing metallogenical provinces: Mongol-Priargun, Gobi-Tamsag, Hentei-Daguur and Northern Mongolia (Fig. 1). Each of these provinces differ by their geological structure, type of uranium deposits, association of minerals and mineralization age.

- Mongol-Priargun metallogenic province is located in Eastern Mongolia and spatially coincides with the same named a continental volcanic belt tracing along the extension some 1,200 km at the wide — ranging width 70–250 km, from Mongolian Altai to

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Priargun. This territory mostly includes deposits and occurrences of fluorite-molybdenum-uranium association caused by volcano-tectonic activization. Distinct fluorite-molybdenum-uranium mineralization districts of Northern-Choibalsan, Berkh, and of Eastern and Central Gobi are included in this area. The Dornod ore knot of Northern Choibalsan area includes uranium deposits of Dornod, Gurvanbulag, Mardai and Nemer as well as polymetals and fluorite.

FIG. 1. Uranium metallogenic provinces and deposits of Mongolia.

- Gobi-Tamsag metallogenic province covers 1,400 km long and 60-180 km wide territory on the southern Mongolia and characterized by numerous uranium occurrences in grey and motley coloured terriginous sediments related to stratum oxidation and restoration. The district units a perspective uranium in the southern part of the same named basin with the deposit named Nars and numerous occurrences as well as perspective uranium-bearing basins like Tamtsag, Sainshand, Zuunbayan and others.

- Hentii-Daguur metallogenic province is 700 km long and 250 km wide territory which includes Hangai and Hentii mountains. In this area uranium occurrences of light colored granite fragments can be found. Uranium occurrences of Janchivlan ore knot can be of interest within this area.

- Northern Mongolian metallogenic province is the biggest and 1,500 km long and 450 km wide area in the Northern and Western Mongolia. This province is comparatively old in its geological structure and is characterized by variety of minerals such as uranium-thorium-rare earth elements related with alkaline mineralization, uranium-thorium in metasomatosis, pegmatite, and magmatic and uranium host rock type of silicon schist. This area is very interesting for exploration and research because of wide variety of origins and geological structure of uranium mineralization and will hopefully attract in the future lots of scientists.

All these metallogenic provinces have ore knots, basins, ore areas each of which is listed in the enclosed table of Uranium Resources. The table shows names of deposits, host rock type, reserves and resources.

Recent and on-going activities

Currently uranium exploration is conducted by the following organizations:

1. "Uran" company, a state owned enterprise dealing with for research and explorations carried out by the Main Directions of Geological Explorations on the Territory of Mongolia.

2. "Gurvansaikhan" company, a joint Mongolian-Russian-American venture, is dealing with explorations, evaluations and research of Choir, Hairkhan, Undurshil, Ulziit and Gurvansaikhan basins. This company will start mining from 1998.

3. "Koge-Gobi" company, joint Mongolian-French venture, is dealing with explorations, evaluations and research of Sainshand, Oshiin Nuur, Nyalga and Tamsag basins. This company will start mining from 2003.

Uranium expenditures and drilling statistics

1995 1996 1997 (expected)

Industry Expenditures (US$ x 1000) 1,400 2,440 3,100 Government Expenditures (US$ x1000) 250 120 35 Total expenditures (US$ X 1000) 1,650 2,560 3,135

Industry surface Drilling in Meters 40,000 41,500 52,000 Number of Industry Holes Drilled 1,000 1,035 1300

The Government of Mongolia supports and encourages uranium geological explorations and planning to conduct geological survey on 32,000 sq.km., explorations on 40,000 sq.km.

and detailed explorations on 4,000 sq.km. of territory for the period till 2005 (See Figure 2).

FIG. 2. Recent developments of uranium geological survey and exploration (1997–2005).

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2. URANIUM RESOURCES

As a result of uranium specialized geological surveys and explorations of 1970–1990, 6 uranium deposits, about 100 occurrences and over 1000 mineralized spots, radioactive anomalies were revealed on the territory of Mongolia.

The following is an evaluation of uranium reserves and resources calculated using mathematical statistical method and based on known of criteria of mineralized regions, radio-geochemical data and tectonic map.

The uranium resources are divided into the following types according to the host rock lithology: (Table I)

TABLE I. URANIUM RESOURCES OF MONGOLIA

Host Rock Age Resources (1000 tU) 1. Uranium association in palaeovalleys, N-Q 30

2. Sandstone type.

Unconsolidated oxidised porous sandstone. K-Q 607 3. Volcanic type. F-Mo-U association. J3-K 183 4. Granitic type. Shatter zones of leucogranites K1-Q 40 5. Uranium association in shatter zone of

granitoids and metamorphits. PR3-T 60 6. Alkaline rock type. U-Th-TR association. PZ2-PZ3 115 7. Metasomatite, migmatic, pegmatic type. PR3 15

8. Flinty shist (shale) type. PR3 60