ISSN 1028334X, Doklady Earth Sciences, 2011, Vol. 437, Part 1, pp. 352–356. © Pleiades Publishing, Ltd., 2011. Published in Russian in Doklady Akademii Nauk, 2011, Vol. 437, No. 1, pp. 85–89.
GEOCHEMISTRY
Uranium in Saline Lakes of Northwestern Mongolia¶ V. P. Isupova, A. G. Vladimirovb, N. Z. Lyakhova, S. L. Shvartsevc, S. Ariunbilegd, M. N. Kolpakovac, S. S. Shatskayaa, L. E. Chupakhinaa, L. V. Kuibidae, and E. N. Morozb Received October 18, 2010
Abstract—Analysis of major and traceelement compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of Ubearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the great est uranium resources are stored in Lake Hyargas Nuur (about 6000 ton). DOI: 10.1134/S1028334X11030032
Saline lakes can store rich unconventional resources of uranium compounds due to input of U leached from rocks by surface and ground waters [1]. Of special interest in this respect are hypersaline closed basin lakes in uranium provinces of Mongolia [2, 3]. According to recent evidence [4, 5], U in some lakes in the North Choibalsan uranium province in Eastern Mongolia is as high as n × 10–4%. High U con centrations were found also in saline lakes in submon tane basins of the Mongolian Altai. The lakes are located in presumably uraniferous areas in which ura nium may reside in country source rocks that are thus the key diagnostic feature for hydromineral uranium exploration. In order to check this hypothesis, we investigated hypersaline soda lakes of Northwestern Mongolia and of the Chuya basin in Gorny Altai (Rus sia). The principal objective was to study geographic ¶ The article was translated by the authors. a
Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia b Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia c Trofimuk Institute of Petroleum Geology and Geophysics, Tomsk Affiliate, Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia d Institute of Geology and Mineral Resources, Mongolian Academy of Sciences, UlaanBaatar, Mongolia e Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
(climatic), geomorphic, and hydrochemical controls of Ubearing saline lakes and, on this basis, to assess their uranium potential. For this purpose we selected several lakes in areas of the Chuya basin (Gorny Altai) and Mongolia (TsaganShibete, Mongolian Altai, MongoliaTuva, and Great Lakes Valley) which were tentatively identified as zones of uranium mineraliza tion after Yu.B. Mironov [2, 3].1 The lakes were explored in the course of joint Rus sianMongolian hydrochemical field trips in 2008 and 2009 (see locations of sampling sites in Fig. 1 and their coordinates in Table 1). Lake water was sampled most often from 30–40 cm depths. The water samples were filtered and collected in 500 ml plastic bottles and in 250 ml polypropylene bottles for analysis of major and trace elements, respectively, and were preserved with highpurity nitric acid to pH 1–2. All bottles were spe cially cleaned before sampling to prevent contamina tion. The samples were analyzed both in field (the field variables рН, Eh, specific conductance, temperature, – 2– concentrations of HCO 3 , CO 3 , and free CO2) and in laboratory, at Institute of Solid State Chemistry and Mechanochemistry (Novosibirsk) and at Water Edu cation, Research, and Development Center of Tomsk Technological University (Tomsk). Uranium and other trace metals (As, B, Mo, etc.) were measured with the ICPMS and ICPAES meth ods, respectively, on an Agilent 7500a mass spectrom eter with inductively coupled plasma and on a Thermo Scientific iCAP 6300 Duo spectrometer. The analyses were performed using deionized water from Direct– 1 In
this communication all zones are interpreted jointly as a potential Mongolian Altai uranium province.
352
URANIUM IN SALINE LAKES OF NORTHWESTERN MONGOLIA 90°
353
95° E Mal yi Ye
Kyzyl
nisei
R.
Russia
7
23 21 20 22
9
Lake Uvs nuur
Tashanta
3978 m Tsagaannuur
Ulangom
13 12 1
Ölgii
H
Lake Hyargas nuur
11 3 6 8 5 10
16
17
14 15
an
50° N ga
18 19
i
R
id
ge
A
Che
l t Lake Shaazgai nuur Hov ai d R. R id Hovd ge China rny i Irt y sh
Za
100° E
vh an
Russia
R. 50° N
Lake Har Us nuur
R.
UlanBator
40 km
Mongolia
4362 m
China
90°
95° 1
2
3
4
5
12
6
Fig. 1. Location map of saline lakes of Northwestern Mongolia and Gorny Altai. 1—Freshwater lakes, 2—saline lakes, 3—saline land, 4—sand, 5—AltaiMongolia uranium province (contoured for Mongolia based on data on potential zones of U mineral ization [2, 3]), 6—sampling sites (labeled by sample numbers as in Table 1). Other symbols: R.—river.
Q 3 UV Millipore, of 18.2 MΩ/cm resistivity at 25°С, with a tuning solution of Agilent 2% HNO3 containing 10 ppb Li, Co, Ce, Y, and Tl. Additionally, measured were Na, K, Mg, Ca, Si, and chloride, sulfate, bicar bonate, and carbonate anions, as well as Li and Sr. Si and the anions were determined following the stan dard procedures for saline water [6]. Na, K, Ca, Mg, Sr, and Li were measured on Saturn2M and Varian AA 280 FS spectrometers in emission or adsorption modes depending on element. According to the analytical results, the sampled lake water has the following composition: total salinity from n × 1.0 to 200 g/l at pH from 7.4 to 9.4 (Table 1); carbonate anions from 0.6 to 540 mg/l, and hydrocar bonates in the range 170–2290 mg/l; chloride anions between 14 mg/l and 100 g/l, and sulfate anions between 21 mg/l and 39 g/l; Na is the dominant cat ion; Mg contents are occasionally rather high. Uranium ranges broadly and reaches 1.0–1.1 mg/l (Table 1). Besides uranium, the lake water contains rather high concentrations of boron (up to 100 mg/l), bromine (up to 460 mg/l), lithium (up to 50 mg/l), and strontium (up to 8 mg/l). The ranges of other metals DOKLADY EARTH SCIENCES
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are (in μg/l): n × 100–n × 10 Ва, n × 100–n × 1 Fe, n × 10 Mo, n × 10–n × 1 Al, Zn, V, n × 10–n × 0.1 Mn, n × 1 Se, Ag, Pb, and n × 1–n × 0.1 Ti. Other analyzed elements are present in amounts under n × 0.1 μg/l. Noteworthy is the concentration of As reaching as high as 250 μg/l in saline lake Shaazgai Nuur. The concentration of uranium correlates strongly – with HC O 3 and As, and with total water salinity (Fig. 2). As for major elements, U is in negative correlation with Mg (–0.316), Ca (–0.245), K (–0.144), and sul fate anions (–0.139), and in positive correlation with Na (0.424) and with chloride (0.431), carbonate (0.685), and bicarbonate (0.710) anions, as well as with the total salinity (0.322) and pH (0.45) of lake water. The relatively high and positive correlation of U with such elements as B (0.438), Si (0.405), and the strong correlation with As (0.901), is implicit evidence of a sulfosalt composition of the source rocks. The uranium in lakes of Northwestern Mongolia is sourced most likely from rift dike complexes that bear MesozoicCenozoic sulfosalt mineralization [2, 3]. If this is the case, the alkaline composition of hypersa
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Tahilt nuur (2009) 48°49′ N, 96°49′ E
Telmen nuur (2009) 48°53′ N, 97°18′ E
Lake Bezymyannoe (2009) 49°58′ N, 88°37′ E
Lake Bezymyannoe (2009) 49°57′ N, 88°44′ E
Lake Bezymyannoe (2009) 49°58′ N, 88°42′ E
18
19
20
21
22
2011
–
–
–
–
8.9
8.9
9.1
8.3
9.4
9.1
8.2
8.2
8.6
7.38
8.3
7.7
9.04
8.6
9.0
7.4
8.5
9.3
9.4
рН
1920
960
8500
–
–
–
Mg
4.2
7
50
100
8.8
60
15
129
20
16
7.7
1.7
75 18
4.8
219
190
590
90
13
145
626
422
1090
61
15
90
2005
226
170
10
37
16
–
–
–
–
–
–
–
–
Chuya basin
60
28
87
–
–
–
–
370
190
240
–
–
–
–
–
–
2310
1300
7530
43100
1150
1880
14.5
1400
1300
17
410
6300
640
4970
–
–
–
–
1100
660
1670
–
1460
1810
170
964
1610
476
670
–
884
960
1380
290
2270
2290
105 1540
2–
–
–
–
–
160
24
340
–
343
400
1.7
5.3
26.8
0.6
1.2
–
154
36
93
–
120
540
460
HCO 3 CO 3
5430
9.8 4260 15800
MongoliaTuva PUP*
208
32
9.0
Cl
15.0 5380
Mongolian Altai PUP*
18
7
50
307
50
240
31
945
58
40
36.0
49400 1000
1930
1880
–
Ca
TsaganShibete PUP*
К
Great Lakes Valley PUP*
22
1320
1440
46
312
7570
810
4250
1590
53100
3020
4240
4750
Na
Note: Dash means not determine; n.f. is not found; * PUP is potential uranium province, after [2, 3].
Lake Bezymyannoe (2009) 50°01′ N, 88°36′ E
Airag nuur (2009) 49°00′ N, 96°06′ E
17
23
Baga nuur (2008) 49°20′ N, 92° 45′ E
Baga nuur (2008) 49°09′ N, 91°55′ E
11
Hyargas nuur (2008) 49°06′ N, 93°45′ E
Shar nuur (2008) 49°01′ N, 91°35′ E
10
16
Hag nuur (2008) 50°11′ N, 91°21′ E
15
Bor Hag nuur (2008) 49°08′ N, 91°24′ E
8
9
Hyargas nuur (2009) 49°06′ N, 93°45′ E
Ureg nuur (2008) 50°05′ N, 91°04′ E
7
14
Sudj nuur (2009) 49°10′ N, 92°06′ E
6
Achit Nuur (2008) 49°24′ N, 90°34′ E
Har Us nuur (2009) 49°04′ N, 91°54′ E
5
13
Davsan nuur (2008) 49°14′ N, 92°03′ E
4
Baga nuur (2008) 49°30′ N, 90°48′ E
Davsan nuur (2009) 49°14′ N, 92°03′ E
3
12
Shaazgai nuur (2008) 49°15′ N, 91°17′ E
2
Lake
and principle components (mg/l), pH, and salinity M (mg/l) in lakes of Northwestern Mongolia
Shaazgai nuur (2009) 49°15′ N, 91°17′ E
238U
1
Sam ple
Table 1.
–
–
–
–
1470
560
6880
19000
1500
1030
21
390
420
30
480
4800
1290
6140
380
–
–
–
–
0.32
8.8
1.93
N.d.
N.d.
0.43
0.13
13.9
4.7
23.5
1.82
0.017
0.013
10.5
7.7
7.1 N.d.
1120
17.8
11.1
SiO2
3.9 ⋅ 104
580
470
2–
SO 4
0.014
0.029
0.015
0.001
0.02
0.02
0.095
0.063
0.070
0.09
0.0031
0.13
0.08
0.043
0.0075
0.42
0.026
0.05
0.07
N.d.
0.013
0.67
1.04
U
238
–
–
–
–
7390
3780
25200
>114700
7880
7480
233
4470
4820
273
1930
>19740
4880
17740
5080
>209500
10660
11950
13560
М, mg/l
354 ISUPOV et al.
URANIUM IN SALINE LAKES OF NORTHWESTERN MONGOLIA C, mg/l 25000 20000
1 2 3
15000 10000 5000
~ ~
2500 2000 1500 1000 500 0 0
0.2
0.4
0.6
0.8
1.0
1.2 U, mg/l
238
Fig. 2. 238U concentration vs. total salinity (M*) (1), – HC O 3 (2), and As (3).
line water and the high contents of bicarbonate and carbonate anions should maintain uranium com 2– plexing with carbonate to produce UO2(CO3 ) 2 , 4– UO2(CO3 ) 3 ,
UO2(CO3)0 [7–11]. When combined with major cations in soda saline water, the uranile complexes form highly soluble compounds which can accumulate in commercial concentrations (1 mg/l or higher). Evaporation in the dry local climate is another factor favorable for relative uranium enrich ment of water. According to preliminary assessment of 238U resources in hypersaline lakes of Northwestern Mongolia based on our own and published water chemistry data [12] (Table 2), the greatest amount of uranium resides in lake Hyargas nuur (6000 t, at mean concentration 0.09 mg/l). The rich U resources are due to the fact that the lake feeds from two large rivers of Western Mongolia (Hovd and Zavhan) which drain Ubearing rocks. The closed basin lake of Shaazgai Nuur, with 238U concentration approaching 1.0 mg/l, is interesting especially as a natural model for investi gating the system “water–Ubearing rock.” (1) The reported study has validated the hypothesis [2, 3] that Northwestern Mongolia may be a high
Table 2. Resource of dissolved 238U in some saline lakes of Northwestern Mongolia Lake Ureg nuur Hyargas nuur Har Us nuur Shaazgai nuur Telmen nuur
Lake volume, 238U concen Total 238U re tration, mg/l sources, ton km3 6.4 [12] 66 [12] 0.3 [12] 0.01 [12] 2.7 [12]
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potential uranium province of Central Asia. Highly saline soda water of closed basin lakes of the area is rich in uranium being thus an unconventional ura nium resource. (2) Among the sampled hypersaline lakes of North western Mongolia and Gorny Altai (Russia), lake Hyargas nuur is worth special attention for its high enrichment in dissolved uranium (0.09 mg/l 238U) that can be extracted with today’s advanced technologies, as well as for its commercial total uranium resources (about 6000 t) that await prospecting (including drill ing and monitoring of water chemistry and environ ment) and innovative development. Data used in this study were kindly shared by Yu.B. Mironov (VSEGEI, St. Petersburg). We also wish to thank D. Tomurhuu, R. Enhtuvshin (IGMR MAS, UlaanBaatar), S.K. Krivonogov, S.Z. Smirnov, N.I. Volkova, and O.P. Gerasimov (IGM, Novosi birsk) for discussions and for their assistance in the field during the trips of 2008 and 2009. ACKNOWLEDGMENTS The study was supported by grant Mong_a 0905 90210 from the Russian Foundation for Basic Research, and was carried out as part of SB RAS Inte gration Projects no. 99 (2006–2008) and no. 38 (2009–2011), as well as SB RAS field trip projects of 2008–2009. REFERENCES 1. Qin Mingkuan, “Current Progresses and Prospects on Unconventional Uranium Resources (UUR) of China,” in Technical Meeting on Uranium from Unconventional Resources, 2009 (Vienna, IAEA Headquarters, 2009); website: http://www.iaea.org/OurWork/ST/NE/ NEFW/documents/RawMaterials/TM_Vienna2009/ presentations/9_QINCHINA.pdf. 2. Yu. B. Mironov, Uranium of Mongolia (CERCAMS, L., 2006). 3. Yu. B. Mironov and Yu. M. Shuvalov, Uranovye Mestor ozhdeniya Mongolii (Uranium Deposits of Mongolia) (VSEGEI, St. Petersburg, 2009). 4. S. Ariunbileg, V. P. Isupov, A. G. Vladimirov, S. K. Kri vonogov, S. S. Shatskaya, and L. V. Kuibida, “Trace Element Composition of Saline Lakes in Eastern Mon golia,” Mong. Geosci. 35, 115–116 (2009). 5. B. S. Linhoff, P. Bennett, T. Puntsag, and O. Gerel, “Geochemical Evolution of Uraniferous Soda Lakes in Eastern Mongolia,” Env. Earth Sci. (2010); DOI: 10.1007/s1266501005128. 6. Yu. Yu. Lur’e, Unifitsirovannye Metody Analiza Vod (Standard Methods for Water Chemistry Analyses) (Khimiya, Moscow, 1971). 7. S. L. Shvartsev, B. N. Ryzhenko, V. A. Alekseev, M. B. Bukaty, V. P. Zverev, O. E. Lepokurova, Geologi cheskaya Evolyutsiya i Samoorganizatsiya Sistemy “VodaPoroda” (Geological Evolution and SelfOrga
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ISUPOV et al. nization in the “WaterRock” System), 5 vols. (SO RAN, Novosibirsk, 2007), vol. 2.
8. A. I. Perelman, Geokhimiya Elementov v Zone Gipergen eza (Chemistry of Elements in Zone of Supergenesis) (Nedra, Moscow, 1972). 9. N. I. Volkova and D. N. Pachadzhanov, “The State of 2+
Th4+ and UO 2 in Surface Water from Zone of Super genesis,” Geokhimiya, No. 11, 1668–1672 (1989).
10. R. F. Spalding, A. D. Druliner, L. S. Whiteside, and W. Struemler, “Uranium Geochemistry in Groundwa ter from Tertiary Sediments,” Geochim. Cosmochim. Acta 48 (12), 2679–2692 (1984). 11. J. I. Drever, “Surface and Groundwater, Weathering, and Soils,” in Treatise on Geochemistry (Elsevier, Perga mon, 2005), vol. 5. 12. Zh. Tserensodom, Mongol Orny Nuuryn Katalog (Cata log of Mongolian Lakes) (Shuuvun Saraal, Ulaanbaa tar, 2000).
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