Rare-earth elements as indicators of ore sources and the degree of differentiation and ore potential of rare-metal granite intrusions (eastern Transbaikalia)

Russian Geology and Geophysics 50 (2009) 29–42 www.elsevier.com/locate/rgg

Rare-earth elements as indicators of ore sources and the degree of differentiation and ore potential of rare-metal granite intrusions (eastern Transbaikalia) V.D. Kozlov Institute of Geochemistry, Siberian Branch of the RAS, 1a ul. Favorskogo, Irkutsk, 664033, Russia Received 2 April 2008; accepted 16 June 2008

Abstract The meteoritic-material-normalized REE patterns of rare-metal granite intrusions of the ore-bearing Kukul’bei complex (J2–J3), eastern Transbaikalia, were studied. It is shown that the intrusions were initially enriched in granitophile volatiles and trace elements (rare metals), i.e., this phenomenon is not related to the differentiation of their parental magma chambers. On the differentiation of the Kukul’bei rare-metal intrusions, the REE contents decrease in passing from granites of the main intrusive phase (MP) to late leucocratic differentiates (muscovite and amazonite granites), the differentiates become more enriched in granitophile elements, and their rare-metal contents drastically increase as compared with the MP granites. The ore-bearing bodies of muscovite and amazonite granites have extremely low REE contents and the highest contents of granitophile (including ore-forming) elements. The REE patterns of the Kukul’bei intrusive differentiates are not universal among rare-metal intrusions. By the example of highly ore-bearing rare-metal granite intrusions of the Erzgebirge, Central Europe, it has been established that their late deep-seated differentiates (ultrarare-metal lithionite-zinnwaldite Li-F-granites) accompanied by highly productive Sn-W mineralization concentrate both granitophile elements and REE (particularly HREE). Among the studied Transbaikalian rare-metal intrusions of the Kukul’bei complex, only the differentiates of the most ore-bearing Sherlovaya Gora intrusive system belong to the above type. The analysis of the REE patterns of the Kukul’bei granites confirmed the earlier conclusions on the low ore potential of the rare-metal mineralization of the studied intrusive complex. © 2009, IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. Keywords: Rare-earth elements; magmatic differentiation; rare-metal granites; granitophile trace elements; rare-metal mineralization; ore potential

Introduction This paper deals with REE patterns of granite varieties — differentiates of hypabyssal ore-bearing intrusions of the Aga zone, eastern Transbaikalia, which are the most productive part of the regional Sn-W metallogenic belt (Smirnov, 1936). Intrusions break through sand-shaly rocks of different ages (T–PR3), which is accompanied by the rock hornfelsing. The intrusions are united into the ore-bearing Kukul’bei graniteleucogranite complex of Middle-Late Jurassic age, composed (as was established earlier) of rare-metal granite varieties enriched in incompatible (granitophile) trace elements (Fig. 1) (Kostitsyn et al., 2000; Kozlov and Svad- kovskaya, 1977). The intrusions of the complex bear Sn-W and rare-metal (Li, Be, Ta) mineralization — magmatogene in Li-F (albitelithionite amazonite) granites as well as greisen, quartz-veined, * Corresponding author.

and endo- and exocontact pegmatite (Laverov, 1995; Levitskii et al., 1963). Figure 1 shows the massifs from which we sampled granites for studying complex REE patterns. Such studies were not carried out earlier. The goal of this work was to analyze the consanguinity of granitoids of the Kukul’bei complex on the basis of their REE patterns and to correlate these results with the rare-metal contents and ore potential of various granites described earlier (Kozlov, 2005a). The REE patterns of granites of the Kukul’bei complex were studied by analysis of composite samples including up to ten geochemical specimens of the same granite variety from a particular object (massif, facies, etc.). The representativeness of the composite samples was repeatedly approved (Kozlov, 2005a). The samples permitted study of the REE patterns of most rare-metal granite varieties from the Kukul’bei complex. The ICP MS results supplemented by earlier data on the petrochemistry of the granites and their concentrations of typomorphic granitophile trace elements (Kozlov, 2005b) are listed in Table 1. The concen-

E-mail address: [email protected] (V.D. Kozlov) 1068-7971/$ - see front matter D 2009, IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. doi:1\0.1016/j.rgg.2008.06.015

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V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

Fig. 1. Massifs (multiphase intrusions) of the ore-bearing Kukul’bei rare-metal granite complex (J2–J3) in the Aga structure-formational zone, eastern Transbaikalia. 1 — massifs of the Kukul’bei complex from which we sampled granites for studying REE patterns (see Table 1); 1–3, 6, 7 — massifs of the Kulinda intrusion; 2 — massifs of the Shakhtama gabbro-diorite-granodiorite complex (J2–J3); 3 — massifs of the Borshchovochnyi gneiss-granite–granite complex (J2–J3); 4 — massifs of batholith granodiorite-granite complexes: Kyra (T–J2) in the west and Unda (P2–T) in the east. Enclosing rocks: sand-shaly (T1), in the western half of the mapped area, and sand-shaly, effusive metamorphosed (PR3), and sand-shaly with effusions (C1–P2), in the eastern half.

tration clarkes (CC) of lanthanides were calculated from the average REE clarkes of granites reported by Ovchinnikov (1990).

The REE patterns of granitoids from the Kukul’bei complex Analysis of the REE patterns of Transbaikalian granites was based on the main concepts of REE distribution in granitoids (Balashov, 1976, 1985; Solodov et al., 1987): (1) relationship of LREE (Ce group, La–Nd (Solodov et al., 1987)) mainly with feldspars and of HREE (Y group, Sm–Lu) with micas and accessory minerals; apatite and fluorite are the main concentrators of all REE; (2) dispersion of most REE of granites in Ca-containing minerals (particularly in plagioclase of felsic differentiates), which is responsible for the ΣREE reduction in successive granite intrusion differentiates as the Ca contents decrease; (3) minor Eu minimum in the meteoritic-material-normalized REE patterns and its increase in successive granite intrusion differentiates owing to the intimate relationship of Eu(II) with Ca, Sr, and Ba, whose concentrations drastically decrease during differentiation;

– – 2− (4) active role of melt volatiles (PO3− 4 , CO3 , B, Cl , F , H2O) in the redistribution of REE, which can be concentrated in microsegregations of many REE-containing minerals paragenetic with all rock-forming elements (Solodov et al., 1987). The above concepts are illustrated by the REE patterns of rare-metal granites from the Erzgebirge, Central Europe, — a region regarded as a reference one in terms of both Sn-W mineralization specific for granites and U mineralization (Kozlov, 2000a,b). According to Tischendorf (1989), the Erzgebirge granite varieties — differentiates of the early Gebirge (OIC) and late ore-bearing Erzgebirge (YIC) complexes — are a typical example of the decreasing REE contents and increasing Eu minimum of successive differentiates (Fig. 2). In the figure, the differentiates from the Gebirge and Erzgebirge complexes are represented by granites of their main phases (OIC1 and YIC1, respectively) and small leucogranite bodies of the extra-intrusion phase (OIC3 and YIC3) (differentiates of granites of the main phases at the site of their intrusion). The Gebirge OIC granites have much higher Ca and REE contents than the YIC leucogranites. The YIC1–YIC3 leucogranites of the late Erzgebirge complex show a successive decrease in Ca and REE contents and growth of the Eu minimum, which is the best pronounced in the YIC3 leucogranites. Still lower REE contents are observed in

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

31

Table 1 Petrochemical, granitophile trace-element, and REE characteristics of intrusion granites from the ore-bearing Middle-Upper Jurassic Kukul’bei complex, eastern Transbaikalia Component

Khangilai intrusion Khangilai massif MP biotite granites

SiO2, wt.% TiO2 Al2O3 Fe2O3 FeO MnO MgO CaO Na2O K2O P2O5 LOI Σ N B, ppm F Li Rb Cs Be Sr Ba Sn W Mo Pb Nb Ta Th U Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu n Eu/Eu* ΣREE CC1 ΣLREE CC2 ΣHREE CC3

FP?

FP dikes?

Spokoinyi dome

Orlovka dome

Exocontact dikes

Greisenized granites

Amazonite Li-Fgranites

Periphery Massif Muscovite granites

Peripheral granite- Trachyrhyoporphyry dacites1

Rhyolites1

Muscovite granites

moderaterly

intensely

After2

After3

1

2

3

4

5

6

7

8

9

10

11

72.62 0.26 14.31 0.66 1.60 0.40 0.50 1.70 3.20 4.50 0.60 0.75 99.35 3 20 530 18 120 5 3.7 330 550 3.2 ∼0.1 1.1 39 14 1.1 14.3 3.8 11 18 37.5 4.3 14.7 3.0 0.66 2.4 0.35 1.9 0.37 1.0 0.19 1.0 0.18 3 0.75 85.55 0.45 74.5 0.47 11.05 0.35

74.01 0.22 14.10 0.74 0.72 0.02 0.33 0.53 3.61 4.72 0.04 0.83 99.88 20 26 880 126 330 16 6.7 140 320 9.6 4.8 0.9 47 21 3.3 37 8.5 20.6 33.8 68.9 7.9 26.5 5.3 0.5 4 0.7 3.5 0.6 1.8 0.3 1.7 0.24 20 0.33 155.74 0.82 137.1 0.87 18.64 0.59

75.97 0.06 14.32 0.42 0.25 0.01 0.12 0.18 3.70 4.28 0.01 0.86 100.58 2 38 800 90 380 20 4.4 40 100 12.5 ∼9 0.5 50 28.1 7.7 18 10.5 17.4 12.9 27.3 3.8 13.8 3.8 0.15 2.9 0.6 3.1 0.6 1.8 0.3 1.9 0.27 2 0.14 73.22 0.39 57.8 0.36 15.4 0.49

74.34 0.66 14.68 0.35 0.30 0.04 0.12 0.72 4.16 3.66 0.02 1.47 99.92 3 240 300 15 120 5 2.0 125 430 2.4 — 0.3 48 16 — 5.7 2.6 11.2 3.5 3.0 1.0 4.3 1.6 0.5 1.9 0.32 1.9 0.37 0.9 1.18 1.0 0.14 4 0.88 20.61 0.11 11.8 0.07 8.81 0.28

67.24 0.24 16.73 1.78 — 0.13 1.15 0.08 0.61 10.32 0.06 0.94 99.28 2 — 1750 ∼500 1620 53 19.3 57 1200 ∼70 17 — — 24 3.9 17.6 5.1 35.2 45.2 83.6 13.3 46.2 11.0 0.95 8.4 1.3 14.5 1.5 4.0 0.62 4.2 0.62 2 0.29 253.39 1.34 188.3 1.19 47.09 1.5

74.10 0.21 14.29 0.70 — 0.03 0.82 0.02 1.01 7.62 0.05 0.90 99.92 1 — 1800 180 ∼600 25 4.6 63 950 30 2.8 — — 18 4.1 15.1 4.0 39.5 33.4 58.8 9.6 31.6 7.9 0.77 7.0 1.1 7.5 1.6 4.8 0.68 4.5 0.68 1 0.33 169.93 0.90 133.4 0.84 36.53 1.16

75.52 <0.01 14.69 0.45 0.21 0.10 0.05 0.23 4.68 2.92 0.02 0.71 99.59 6 56 840 45 460 18 39 60 70 45 >60 1.9 15 81 10 5.9 1.8 4.2 35.9 65.3 8.4 30 5.2 1.48 4.2 0.6 3.1 0.6 1.6 0.25 1.4 0.21 6 0.97 158.24 0.83 139.6 0.88 18.64 0.59

76.09 0.05 14.10 0.17 0.46 0.12 0.20 0.28 3.62 3.38 0.08 1.32 99.87 2 31 1800 120 470 70 27 100 100 54 >80 0.6 37 84 — — — 9 10 ∼20 — 9 — — — — — — — — ∼0.7 — 2 — — — — — — —

81.20 0.03 11.88 0.53 0.27 0.15 0.09 0.26 0.34 3.58 0.03 1.45 99.73 4 320 2850 120 470 37.5 43 60 30 65 >80 0.4 24 80 18 7.2 2.6 5.2 3.9 4.2 1.0 3.8 1.4 0.07 1.2 0.22 1.0 0.14 0.33 0.07 0.5 0.07 4 0.16 17.9 0.09 12.9 0.08 5 0.16

71.39 0.01 16.31 0.48 0.65 0.25 0.20 0.42 5.24 3.88 0.02 0.29 99.14 — — 6900 — 1000 18 — 20 32 — — — — 81 55 14 2 2 5.9 17 — 6.9 2 0.07 1.4 — — — — — 0.75 0.3 — 0.13 — — — — — —

71.88 0.01 15.97 0.46 0.52 0.24 0.14 0.27 5.65 2.98 — — 98.12 7 — 12000 1175 1225 31 5 6 55 11 11 — — 84 75 — — — — — — — — — — — — — — — — — 103 — — — — — — —

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V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

Table 1 (continued) Component

Sakhanai intrusion Sakhanai massif

SiO2, wt.% TiO2 Al2O3 Fe2O3 FeO MnO MgO CaO Na2O K2O P2O5 LOI Σ N B, ppm F Li Rb Cs Be Sr Ba Sn W Mo Pb Nb Ta Th U Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu n Eu/Eu* ΣREE CC1 ΣLREE CC2 ΣHREE CC3

Durulgui intrusion Zun-Undur massif

Durulgui dome

Eastern part

MP biotite granites

EIP two-mica EIP two-mica FP muscovite granites granites granites apical inner

MP coarse-grained granites biotite

two-mica

dome muscovite

EIP pegmatitebearing muscovite granites

12

13

14

15

16

17

18

19

20

73.43 0.23 13.95 0.34 2.08 0.06 0.21 0.83 3.52 4.83 0.07 0.65 100.20 6 54 1300 110 270 18 5.9 130 300 13 3.5 — 25 19 3.6 32 13.4 31.3 38.6 86.7 10.7 40.2 8.7 0.74 6.8 1.1 7 1.23 3.9 0.6 3.8 0.58 13 0.29 210.65 1.11 176.2 1.11 34.45 1.1

75.05 0.17 12.54 0.60 1.73 0.06 0.27 0.77 3.65 4.42 0.06 0.47 99.79 2 96 1800 200 300 30 13 120 270 23 4.4 1.3 26 22 4.1 31 20 21 35 78.2 9.4 36.2 7.1 0.77 6 0.94 5.2 0.9 2.7 0.4 2.7 0.39 3 0.36 185.9 0.99 158.8 1.00 27.1 0.86

74.86 0.04 14.03 0.45 1.60 0.04 0.20 0.42 3.88 4.49 N.f. 0.84 100.95 3 100 2250 170 330 32 13 90 150 28 7.8 7 21 23 7.6 19 19 13.7 13.4 28 3.8 15.5 3.7 0.33 3.6 0.6 3.8 0.62 1.7 0.24 1.5 0.19 10 0.28 76.98 0.41 60.7 0.38 16.28 0.52

74.33 0.03 13.38 0.37 1.61 0.08 0.11 0.32 3.69 4.12 N.f. 0.86 99.90 3 45 2850 270 450 40 20 80 130 ∼40 12 0.7 20 32 14 10 9.6 14.1 11.6 25 2.8 9.7 2.5 0.15 2.4 0.3 2.4 0.41 1.1 0.14 1.14 0.11 6 0.18 59.75 0.31 49.1 0.31 10.65 0.34

74.24 0.03 13.40 0.50 1.29 0.08 0.11 0.45 3.98 4.09 N.f. 1.02 100.19 2 37 3700 300 445 36 23 45 120 75 14 1.6 15 28 13 13 15.4 10.3 8.1 15.6 2.5 10.6 2.7 0.21 2.6 0.45 2.8 0.46 1.4 0.22 1.5 0.19 5 0.24 61.63 0.32 49.1 0.31 12.53 0.40

73.12 0.29 14.11 0.22 1.84 0.04 0.45 0.95 3.40 5.07 0.16 0.55 100.20 4 20 750 120 270 17 6.6 200 320 13 ∼1.3 5.4 24 22 3.5 29 11.9 22.8 38.2 81.8 9.2 31.5 5.9 0.54 5.0 0.63 4.1 0.79 2.1 0.32 2.2 0.35 9 0.31 182.63 0.96 167.7 1.01 21.93 0.70

73.13 0.23 15.30 0.36 1.67 0.07 0.33 0.83 3.50 4.26 0.11 0.85 99.64 5 30 ∼1100 200 300 27 11.5 100 150 ∼23 ∼7 — 21 19 3.5 18 12.2 12 18.6 37.3 4.2 14.7 2.6 0.37 2.1 0.31 2.2 0.41 1.2 0.26 0.8 0.17 10 0.47 85.22 0.45 74.8 0.47 10.42 0.33

74.05 0.05 15.33 0.24 1.17 0.14 N.f. 0.35 3.67 4.15 0.27 0.83 100.25 3 29 1800 260 560 53 25.3 50 45 42 >200 ∼5 13 38 17 5.4 15 7.8 5.5 12.3 1.4 5.0 1.1 0.1 1.1 0.22 1.4 0.25 0.64 0.1 0.9 0.12 6 0.28 30.13 0.16 24.2 0.15 5.93 0.19

74.30 0.06 15.00 0.41 0.52 0.11 N.f. 0.52 4.11 3.80 0.02 0.67 99.52 9 22 350 45 275 8 14 30 60 16 4.7 0.6 21 30 11 8.4 4.6 20.8 4.7 11.1 1.4 4.9 1.7 0.07 1.6 0.3 2.7 0.56 1.9 0.31 2.4 0.35 11 013 33.99 0.18 22.1 0.14 11.89 0.38

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

33

Table 1 (continued) Component

Kulinda intrusion and massifs (massif numbers follow Fig. 1) 1

SiO2, wt.% TiO2 Al2O3 Fe2O3 FeO MnO MgO CaO Na2O K2O P2O5 LOI Σ N B, ppm F Li Rb Cs Be Sr Ba Sn W Mo Pb Nb Ta Th U Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu n Eu/Eu* ΣREE CC1 ΣLREE CC2 ΣHREE CC3

2

3

6

7

Sedlovskii Kanga intrusion massif Malaya Kanga massif, right bank of the Onon River

Zavitinskii massifs, left bank of the Onon River

Belukha massif

EP MP biotite MP biotite granites monzodio granites rites from outer inner intrusion zone ultrarareperiphery metal

FP pegmatite-bearing muscovite granites KharaShibir group

Bogov Utes

MP biotite MP biotite FP granites granites muscovite granites

MP FP granites muscovite PM-33164 granites

MP biotite granites

21

22

23

24

25

26

27

28

29

30

31

32

63.19 1.00 16.53 0.33 3.97 0.07 2.07 3.10 4.18 3.61 0.42 0.87 99.34 6 22 2500 650 290 135 7 1050 1960 42 17 0.7 24 21 1.6 15 4.7 16.1 68.6 140.9 15.9 58 9.6 2.16 6.7 0.8 3.8 0.66 1.8 0.32 1.3 0.32 6 0.82 310.86 1.68 283.4 1.70 27.46 0.87

72.50 0.38 14.32 0.63 0.76 N.f. 0.45 1.01 3.76 5.06 0.04 0.87 99.78 4 21 850 32 230 9 3.8 300 940 3.7 5.0 — 35 8 0.9 42 5.5 8.0 55.0 112.3 11.6 41.1 6.5 1.08 3.9 0.4 2.0 0.30 0.8 0.11 0.72 0.10 8 0.66 235.9 1.24 220 1.39 15.91 0.51

71.46 0.44 14.85 0.36 1.51 0.01 0.63 1.12 3.84 5.01 0.10 0.64 99.97 9 22 1150 65 215 21 4.7 340 710 9.6 1.4 <1 32 10 1.4 35 4.2 9.3 48.9 195.4 10.4 40.1 6.2 1.12 4.2 0.5 2.2 0.38 1.0 0.11 0.77 0.11 14 0.67 221.35 1.17 204.8 1.29 16.59 0.53

71.02 0.50 14.76 0.58 1.41 0.01 0.60 1.38 3.54 4.74 0.12 0.57 99.29 5 30 1780 290 235 60 11 390 860 28 2 <1 32 10 1 35 5.3 8.4 47.7 108.3 10.3 39.2 6.4 1.05 4.3 0.4 2.3 0.34 1.0 0.11 0.76 0.11 7 0.61 222.27 1.17 205.5 1.30 16.77 0.53

74.78 0.01 14.81 0.22 0.45 0.18 0.07 0.30 5.28 3.05 0.14 0.67 99.96 6 46 550 100 290 18 16.5 45 125 15 7 1.0 15 24 7.3 6.5 7.2 5.4 5.1 7.6 1.1 4 0.66 0.13 0.64 0.12 0.88 0.11 0.58 0.11 0.77 0.11 7 0.61 21.91 0.12 17.8 0.11. 4.11 0.13

75.17 0.02 14.44 0.38 0.74 0.08 N.f. 0.37 4.90 4.04 0.06 0.57 100.32 6 20 900 90 500 12 8.6 20 ∼40 48 2.3 1.1 24 59 24 3.5 3.0 8.8 2.0 4.9 0.6 2.0 0.78 0.05 1.0 0.19 1.1 0.27 0.74 0.13 1.0 0.14 6 0.17 14.9 0.08 9.5 0.06 5.4 0.17

73.23 0.31 14.01 0.75 1.36 0.03 0.41 1.00 3.40 4.81 0.04 0.48 99.83 10 24 850 55 205 6.6 4.7 170 335 6.2 1.1 2 30 17.4 1.4 31 4.1 23.2 46.5 111.8 9.9 38.4 5.3 0.68 5.0 0.61 4.3 0.79 2.3 0.39 1.7 0.38 18 0.4 228.05 1.20 206.6 1.3 21.45 0.4

72.33 0.36 14.40 0.75 1.03 0.03 0.48 1.40 4.11 4.20 0.09 0.65 99.83 7 17 1050 165 235 14 7.3 230 270 13.7 0.9 3.2 34 12 2.7 23 4.5 5.9 19.6 45.6 4.2 14.6 2.1 0.47 1.7 0.21 1.5 0.27 0.57 0.11 0.38 0.12 12 0.76 91.43 0.48 84 0.53 7.43 024

75.38 0.06 14.15 0.49 0.21 0.04 0.11 0.62 4.14 4.02 0.02 0.60 99.84 8 55 400 90 345 19 8.3 80 80 19 2.4 1.1 39 34 5.9 12 5.4 22 10 22.1 2.7 9.4 28 0.24 3.0 0.4 3.0 0.66 1.9 0.5 2.9 0.52 11 0.26 60.12 0.32 44.2 0.28 15.92 0.51

73.41 0.14 14.84 1.15 — 0.04 0.20 0.79 3.80 4.69 0.15 0.78 99.99 1 — 600 240 415 39 12 90 180 22 1.0 — 22 33 7.4 — — 7.7 21.5 42.2 4.1 16.2 2.8 0.24 2.15 0.23 1.8 0.27 0.62 0.11 0.36 0.09 1 0.30 92.67 0.49 84 0.53 8.67 0.28

75.96 0.01 13.86 0.68 N.f. 0.04 0.15 0.39 4.54 3.92 N.f. 0.56 100.11 1 — 200 114 330 10 — 22 49 14.4 1.6 — 30 — — — — 6.9 2.3 5.3 0.56 2.15 0.73 0.09 0.58 0.12 0.92 0.17 0.45 0.03 0.31 0.06 1 0.40 13.77 0.07 10.31 0.065 3.46 0.11

73.11 0.31 14.17 0.85 0.64 0.02 0.52 1.20 3.81 4.70 0.03 0.54 99.30 9 20 1050 140 310 33 8.3 240 460 6.2 ∼14 1.5 44 13 1.3 28 9.3 8.4 28.7 54.5 5.6 17.9 3.1 0.52 2.3 0.28 1.2 0.28 0.73 0.09 0.48 0.13 12 0.60 115.81 0.61 106.7 0.68 9.11 0.29

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V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

Table 1 (continued) Component

SiO2, wt.% TiO2 Al2O3 Fe2O3 FeO MnO MgO CaO Na2O K2O P2O5 LOI Σ N B, ppm F Li Rb Cs Be Sr Ba Sn W Mo Pb Nb Ta Th U Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu n Eu/Eu* ΣREE CC1 ΣLREE

Oldonda massif

Soktui massif Turga massif

Etyka massif

Sherlovaya Gora intrusion MP biotite granites

MP biotite FP twogranites mica granites

FP(?) muscovite granites

MP biotite granites2

MP FP amaleucogranites zonite granites

Amazonite Dome Quartz without with Eu granites leucogranites porphyry Eu minimum (ongonites) minimum

33

34

35

36

37

38

39

40

41

42

43

72.58 0.28 14.73 0.76 0.76 0.02 0.54 1.23 3.98 4.42 0.06 0.52 99.88 5 20 ∼800 95 260 20 5.2 280 440 4.4 2 1.2 47 12 1.4 28 9.2 7.4 29.9 56.7 6.0 20.6 3.3 0.55 2.1 0.2 1.15 0.18 0.66 0.10 0.58 0.10 6 0.64 122.12 0.64 113.2

73.94 0.21 13.88 0.61 0.79 0.03 0.23 0.77 3.66 4.91 0.02 0.73 99.78 10 19 1050 110 370 24 8.5 110 270 13.7 1.6 0.7 42 22 5.6 52 14 17.3 44.8 93.9 10.4 35.1 6.5 0.44 4.5 0.58 3.3 0.72 1.7 0.39 1.36 0.40 5 0.25 204.09 1.08 184.2

77.80 0.08 12.07 0.47 0.25 0.013 0.14 0.35 3.20 4.43 N.f. 0.90 99.80 3 17 1850 55 400 14 7.2 65 90 24 9.6 3.8 35 32 10 19 9.2 27.4 17.3 39.1 4.3 14.5 3.7 0.11 3.6 0.56 4.0 0.78 2.4 0.36 2.6 0.31 4 0.095 93.62 0.49 75.2

74.01 0.18 13.35 0.66 1.08 0.03 0.18 0.81 375 4.97 0.06 0.52 99.88 — 18 3000 79 470 20 6.5 73 180 4.9 2.1 — 19 26 6 — — 32 55 105 — 53 8.3 0.48 10 — — — — — 2.5 0.3 — — — — —

76.48 0.10 12.55 0.83 0.49 0.01 0.05 0.44 3.59 4.73 N.f. 0.53 99.80 8 11 250 20 215 7 4.9 30 47 6 1.5 2.0 32 35 3.9 35 11 23.2 60.2 115 13 44.4 6.8 0.16 5.85 0.74 4.7 1.0 2.7 0.6 2.05 0.43 13 0.08 257.63 1.36 232.6

77.31 0.02 12.36 0.67 0.48 0.02 0.03 0.13 3.79 4.45 N.f. 0.57 99.83 5 11 1700 175 700 20 5 ∼15 ∼50 13.2 ∼1.3 1.6 76 93 9.2 39 13 28 7.6 40.7 3.6 14.2 5.3 0.04 4.3 0.64 4.5 0.89 2.7 0.47 3.2 0.49 4 0.05 88.63 0.47 66.1

71.75 0.01 17.98 <0.01 0.36 0.034 0.067 0.053 5.54 3.66 0.011 0.44 99.92 1 9 3100 290 1500 15 3.3 ∼15 ∼20 300 6.7 1.6 ∼200 100 109 5.6 13.8 2.45 0.58 0.87 0.60 2.0 0.63 0.03 0.51 0.12 1.06 0.2 0.87 0.19 1.92 0.3 1 0.14 9.88 0.05 4.05

76.21 0.05 13.09 0.44 0.72 N.f. 0.06 0.29 2.85 4.54 N.f. 0.96 99.21 4 46 5500 130 390 — 8.0 10 ∼20 15 12 6 33 59 3.1 50 13.9 83 40 95.7 12.7 48.3 12.8 0.042 10 2.1 12.7 2.6 7.7 1.2 7.0 1.0 2 0.01 253.84 1.34 196.7

73.72 N.f. 14.54 0.46 0.38 0.05 0.08 0.78 4.57 4.36 N.f. 0.94 99.88 8 230 6000 228 632 23 21 15 ∼20 40 7 — 70 94 5.4 28 11.5 143 5.6 14.5 2.3 10.6 6.5 0.006 9.6 2.6 17.4 4.2 13.2 2.1 12.7 1.7 6 0.002 103.01 0.54 33

72.42 0.35 14.49 0.72 0.91 0.02 0.52 1.25 3.90 4.56 0.07 0.60 99.81 39 20 1040 100 260 24 6.8 270 500 9.5 ∼5 ∼1.7 40 12 ∼1.6 29 7.0 7.6 32.2 66.4 6.6 23.3 3.7 0.66 2.6 0.28 1.5 0.27 0.72 0.10 0.55 0.12 59 0.65 139.0 0.73 1285

73.54 0.23 14.06 0.54 1.42 0.04 0.30 0.82 3.58 4.81 0.05 0.64 100.03 >50 28 ∼1230 120 330 20 6.9 135 270 11.5 2.3 ∼2 28 23 4.2 ∼32 9.5 22.9 38.9 82.7 8.4 34.3 6.1 0.53 5.5 0.65 4.1 0.74 2.14 0.34 2.04 0.32 >60 0.28 186.76 0.98 164.3

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

35

Table 1 (continued) Component

CC2 ΣHREE CC3

Oldonda massif

Soktui massif Turga massif

Etyka massif

Sherlovaya Gora intrusion

MP biotite granites

MP biotite MP twogranites mica granites

FP(?) muscovite granites

MP biotite granites2

MP Amazonite Amazonite Dome Quartz without with Eu leucogranites granites granites leucogranites porphyry Eu minimum (ongonites) minimum

33

34

35

36

37

38

39

40

41

42

43

0.71 8.92 0.28

1.16 19.89 0.63

0.47 18.42 0.59

— — —

1.47 25.03 0.8

0.42 22.53 0.72

0.03 5.83 0.19

1.24 57.14 1.82

0.21 70.01 2.23

0.81 10.5 0.33

1.04 22.46 0.72

Note. Data were obtained in the analytical laboratories of the Institute of Geochemistry, Irkutsk. The petrochemical composition of granitoids was determined by X-ray spectral analysis on a CRM-25 quantometer. The contents of rare alkaline metals (Li, Rb, Cs) were determined by the flame photometry method; the contents of Sr, Ba, Zr, and Nb, by quantitative X-ray spectral analysis; the contents of B, F, Be, Sn, W, Mo, Pb, Zn, Sc, V, Ni, and Co, by quantitative emission spectral analysis; and the contents of Y, REE (14 elements), Hf, Th, and U, by the solution method on an ICP MS equipment. Analyses were carried out by T.S. Aisueva (Sr, Ba, Nb, Zr), O.M. Chernyshova (F, Be), N.L. Chumakova (B, Cu, Zn, Mo, Sn, Pb), S.S. Vorob’eva (Sc, Cr, V, Co, Ni), and E.V. Smirnova and G.P. Sandimirova (Sc, Cr, V, Co, Ni, REE, Y, Nb, Hf, Th, U, and some other elements). LOI — loss on ignition; Σ — total content; N — number of samples for chemical analysis; n — number of samples for trace-element analysis; dash — no data; ΣREE — total content of REE; ΣLREE — total content of light REE (La, Ce, Pr, Nd); ΣHREE — total content of heavy REE (Sm–Lu, after Solodov et al. (1987); CC1, CC2, and CC3 – ratios of the corresponding ΣREE contents of a given granite variety to their total clarke contents (ΣREECL = 189.8 ppm, ΣLREECL = 158.4 ppm; Σ HREECL = 31.4 ppm, after Ovchinnikov (1990). Intrusive phases: EP — early, MP — main, EIP — extra-intrusion, FP — final. 1 After Syritso et al. (2005); 2 after Kovalenko et al. (1999); 3 after Syritso et al. (2001); 4 after Zagorskii and Kuznetsova (1990).

Fig. 2. Chondrite(C1)-normalized (Taylor and McLennan, 1985) REE patterns of the Erzgebirge (Central Europe) ore-bearing rare-metal granites. OIC — ancient complex (oblique hatching), YIC — young complex (vertical hatching); OIC1 and YIC1 — granites and leucogranites of the main phases, OIC3 and YIC3 — leucogranites of the extra-intrusion phase, YICm — ultrarare-metal granites of stocks and domes of the final phase of the young complex; YIC1/1 — Vykmanov dome; GR — greisens of the young complex; D — monzosyenites (durbachites) of the Middle Czech Massif. 1 — granitoids of the early phase (EP), 2 — granites of the main phase (MP), 3 — leucogranites of the extra-intrusion phase (EIP) and the final phase (FP), 4 — EIP and FP two-mica granites, 5 — EIP and FP pegmatite-bearing muscovite leucogranites, 6 — MP dome muscovite leucogranites, 7 — greisenized muscovite granites and greisens, 8 — FP dome ultrarare-metal leucogranites, 9 — ultrarare-metal subvolcanic bodies and dikes, including ongonites, 10 — FP ultrarare-metal amazonite granites, 11 — monzosyenites (durbachites).

quartz-topaz greisens related to the Erzgebirge YIC1/1 leucogranites (Fig. 2, GR) (Štemprok et al., 2005); moreover, the REE patterns of the YIC1 granites agree with those of the YIC1/1 leucogranites. In contrast to the successive Erzgebirge granite differentiates with gradually decreasing REE contents, the ultrararemetal albite-lithionite-zinnwaldite (Li-F) granites from the Schellerhau stock show an absolutely different REE pattern (Fig. 2, YICm). This stock is one of the local domes of the Gebirge complex, which bear the most productive Sn-W mineralization of the Erzgebirge (Krupka, Cinovec, Zinnwald, Sadisdorf, Altenberg, and other deposits) (Rundkvist et al., 1972; Tischendorf, 1986). These granites have ultrahigh contents of volatiles F (8000 ppm) and B (100 ppm), rare alkalies Li (1000 ppm), Rb (1100 ppm), and Ce (80 ppm), and ore-producing metals Sn (100 ppm) and W (50 ppm) (Kozlov, 2000a) and are obviously late deep-seated differentiates highly enriched in volatiles and trace elements that formed in the magma chambers of the Erzgebirge complex. The granites contain granitophile elements, abound in both HREE and LREE, and show a deep Eu minimum. This specific feature breaking the above rule of ΣREE decrease in successive differentiates (see item (2) above) is due to the redistribution of REE under the influence of volatiles when the latter saturate the melts (see item (4) above), which is just the case in the studied ultrarare-metal differentiates (Kozlov, 1985). Actually, two tendencies are observed in the HREE distribution on differentiation of rare-metal granite intrusions: the depletion of successive leucogranite differentiates in HREE as the Ca contents decrease and, on the contrary, enrichment of late melts in HREE under the influence of abundant volatiles. In the REE patterns of granitoids, the intensity of the Eu minimum reflects the intensity of magmatic differentiation of initial melts and their depletion in Ca. The Eu minimum

36

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

Fig. 3. REE patterns of granites from: a — Khangilai intrusion, b — Sakhanai and Zun-Undur massifs, c — Durulgui intrusion, d — Sedlovskii, Malaya Kanga, and Zavitinskii massifs, e — Kulinda massifs, f — Soktui, Belukha, and Oldonda massifs. Pattern numbers follow analysis numbers in Table 1. Designations follow Fig. 2.

intensity is estimated from the Eu/Eu* ratio (Taylor and McLennan, 1985). Its minimum values are typical of differentiates with the most pronounced leucogranitic composition (Table 1). As a reference ore-bearing system of eastern Transbaikalia, we earlier considered the REE patterns of granites of the Khangilai intrusion (Kozlov, 2005a), whose muscovite leucogranites bear wolframite-greisen mineralization (Spokoininskoe deposit) and amazonite L-F-granites bear the Orlovka Ta deposit. The REE patterns of the intrusion rocks (Fig. 3, a) are supplemented by data on obviously late dike-like ultrapo-

tassic and ultrarare-metal F- and rare-alkali-enriched differentiates of trachyrhyolite-rhyolite composition (Syritso et al., 2005). The REE patterns of these differentiates (5 and 6) similar to that of the MP granites (2) with the same shallow Eu minimum (Eu/Eu* = 0.29–0.33) differ from the other Khangilai granites in showing the highest contents of both HREE and LREE (like the REE pattern of the Erzgebirge lithionite-zinnwaldite granites). As seen from the REE patterns, the studied intrusive systems and massifs of the Kukul’bei complex of the Aga zone are dominated by moderately differentiated intrusions

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

37

Fig. 4. REE patterns of the FP amazonite granites from the Khangilai intrusion and Turga and Etyka massifs. Pattern numbers follow analysis numbers in Table 1. Designations follow Fig. 2.

Fig. 5. REE patterns of the FP dome leucogranties and ongonites from the Sherlovaya Gora intrusion and the MP granites from the reference Soktui massif. Pattern numbers follow analysis numbers in Table 1. Designations follow Fig. 2.

with a distinct shallow Eu minimum (Eu/Eu* = 0.26–0.4) of the MP granites and their leucogranite differentiates. These are the Sakhanai and Zun-Undur massifs (Fig. 3, b, patterns 12–16), Durulgui intrusion (Fig. 3, c, patterns 17–20), and Sedlovskii, Malaya Kanga, and Zavitinskii massifs (Fig. 3, d, patterns 27 and 29–31). At the same time, the MP granites of some massifs of the studied intrusions virtually lack a Eu minimum (Eu/Eu* = 0.6–0.8). This means that the initial melts of these intrusions did not undergo a significant magmatic differentiation. In the Khangilai intrusion, these are granites of the Ubzhigoi peripheral dome (Table 1, column 1) (Kozlov, 2005a), Malaya Kanga massif (Fig. 3, d, pattern 28), Kulinda massifs (Fig. 3, e, patterns 21–24), and Oldonda and Belukha massifs (Fig. 3, f, patterns 32 and 33). The REE patterns of ultrarare-metal amazonite Li-F-granites from local massifs (Fig. 4, patterns 10, 38, and 39) show distinct Eu minima (Eu/Eu* = 0.14–0.05), low contents of LREE, and somewhat reduced contents of HREE as compared with the MP granites and clarke granite (Table 1, columns 38 and 39, CC1, CC2, and CC3 values). A similar irregular decrease in the contents of REE (especially LREE) is observed in the dome MP muscovite granites and pegmatite-bearing muscovite granites (Fig. 3, c, patterns 19 and 20; d, 29 and 31; e, 25 and 26; f, 35). Figure 5 presents the REE patterns of leucogranites from the Sherlovaya Gora dome and their subvolcanic analogs — ultrarare-metal quartz porphyry (ongonites) (Antipin et al., 1980) from the Sherlovaya Gora intrusion (sampled by Troshin et al., 1983). The patterns show ultradeep Eu minima (Eu/Eu* = 0.01–0.002) and high contents of HREE (Table 1, columns 40 and 41, CC3 values), i.e., they are similar to the REE patterns of the ore-bearing Erzgebirge dome lithionite-

zinnwald Li-F-granites (Fig. 2). A specific feature of the ongonites is a significant decrease in LREE contents (Fig. 5, pattern 41), which was earlier observed in ongonites from the Balgi Gol massif in the Henteyn region, Mongolia (Kovalenko et al., 1983).

Discussion Formation of rare-metal granites enriched in volatiles and trace elements, including ore-producing ones (Sn, W, Mo, Ta, Be, Li), was earlier accounted for by the intense deep-level differentiation of granitoid magmas (Koptev-Dvornikov and Rub, 1964; Kovalenko, 1977; Kozlov and Svadkovskaya, 1977; Tauson, 1977; Troshin et al., 1983). For example, Academician L.V. Tauson related the formation of rare-metal plumasite and alkali (agpaitic) rare-metal granites to the differentiation of the magma chambers of palyngenetic granitoid melts and alkali-basaltoid magma chambers, respectively. Since the degree of differentiation of granites is reflected in the intensity of Eu minimum (the degree of Eu/Eu* decrease) in their REE patterns, this permits one to verify the hypothesis that the melts of the Kukul’bei rare-metal granites are differentiates of magma chambers of granitoid melts. Based on the intensity of the Eu minimum in the REE patterns of the MP granites of the Kukul’bei complex, we compiled two columns of their average compositions (Table 1, columns 42 and 43). The first column includes intrusions whose MP granites almost lack a Eu minimum (Fig. 3, d–f; Table 1, columns 22–24, 28, 32, and 33). The second column includes the average compositions of the MP granites with a distinct Eu minimum (Fig. 3, a–d, f; Table 1, columns 2, 12, 17, 27, 30, and 36). For these compositions of MP granites,

38

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

Table 2 Trace-element composition of various rare-metal granites (Table 1) expressed as elemental formulas and concentration indices (CI) of granitophile elements Multiphase intrusions and massifs

Intrusive phase and granite variety. Elemental formula

CI (parenthesized is Column the number of number granitophile elements) in Table 1

MP, biotite granites Without Eu minimum Cs4.8 − W3.3 − Sn3.2 − Li2.5 − Be2.3 − Pb2 − U2 − Mo1.7 − Th1.6 − Rb1.5 − B1.3 − F1.3 Ta0.4 − Ba0.6 − Sr0.9 (Table 1, columns 22– 24, 28, 32, and 33)

+14.9 (13)

42

With Eu minimum (columns 2, 12, 17, 27, 30, and 36)

Cs4 − Sn3.8 − Li3 − U2.7 − Be2.3 − Mo2 − B1.9 − Rb1.9 − Th1.8 − F1.5 − W1.5 − Pb1.4 − Ta1.2 Ba0.3 − Sr0.4

+16.0 (13)

43

Khangilai

Li3.2 − Cs3.2 − Sn3.2 − W3.2 − Pb2.4 − U2.4 − Be2.2 − Th2 − Rb1.9 − B1.7 − F1.1 Ba0.4 − Sr0.5 − Mo0.9 − Ta0.9

+15.7 (13)

2

EIP–FP, dome muscovite granites Khangilai

W > 53 − Sn18 − Cs14 − Be9 − Li3 − Rb2.8 − F2.2 − B2.1 − Pb1.8 Ba0.1 − Sr0.3 − Mo0.6

>96 (10)

9

Zun-Undur

Sn25 − W9.3 − Be7.7 − Li7.5 − Cs7.2 − F4.6 − U4.4 − Ta3.7 − Rb2.6 − B2.5 − Mo1.6 Sr0.1 − Ba0.1 − Pb0.7 − Th0.7

+64.5 (13)

16

Durulgui

W > 130 − Cs10.6 − Be8.4 − Sn8.4 − Li6.5 − Mo5 − Ta4.9 − U4.3 − Pb3.3 − F2.2 − B1.9 Ba < 0.1 − Sr0.2 − Th0.3 − Pb0.6

>170 (13)

19

Oldonda

Sn8 − W6.4 − Mo3.8 − Ta2.9 − Cs2.8 − U2.6 − Rb2.4 − Be2.4 − F2.3 − Pb1.8 − Li1.4 − B1.1 − Th1.1 Ba0.1 − Sr0.2

+26 (13)

35

EIP–FP, pegmatite-bearing muscovite granites Durulgui

Sn5.3 − Be4.7 − W3.1 − Ta3.1 − Rb1.6 − Cs1.6 − B1.5 − U1.3 − Li1.1 − Pb1 Ba < 0.1 − Sr0.1 − F0.4 − Th0.5 − Mo0.6

+12.8 (13)

20

Kulinda, massif 6

Be5.5 − Sn5 − W4.7 − Cs3.6 − B3.1 − Li2.5 − Ta2.1 − U2.1 − Rb1.7 − Mo1 Sr0.15 − Ba0.15 − Th0.4 − F0.7 − Pb0.8

+20.2 (13)

25

Kulinda, massif 7

Sn16 − Ta6.9 − Rb2.9 − Be2.9 − Cs2.4 − Li2.2 − W1.5 − B1.3 − Pb1.2 − F1.1 − Mo1.1 Sr < 0.1 − Ba < 0.1 − Th0.2 − U0.9

+27.6 (13)

26

Malaya Kanga

Sn6.3 − Cs3.8 − B3.7 − Be2.8 − Li2.2 − Rb2.0 − Pb2.0 − Ta1.7 − W1.6 − U1.5 − Mo1.1 F0.5 − Ba0.1 − Sr0.3 − Th0.7

+17 (13)

29

FP, dome leucogranites Sherlovaya Gora

W8.7 − F7.8 − Sn6.3 − Mo6 − U4 − Cs3.6 − Li3.4 − B3.4 − Rb3.3 − Th2.8 − Be2.7 − Pb1.7 Sr < 0.1 − Ba < 0.1 − Ta0.9

+38.2 (13)

40

Erzgebirge, granites (YICm)

Sn33.3 − W33.3 − Li25 − Cs16 − F10 − B6.7 − Rb6.5 − Be4.8 − Ui4.3 − Pb1.5 Sr < 0.1 − Ba < 0.1 − Th0.7

+131.1 (11)

*

FP, dikes and subvolcanic ultrarare-metal felsic differentiates Khangilai

Sn10 − Cs5 − Li4.5 − Rb3.5 − F2.2 − W1.9 − Be1.5 − Ta1.2 − U1.1 − Ba1.2 Sr0.2 − Th0.8

+21.7 (10)

6

Sherlovaya Gora

B15.3 − Sn13.3 − F7.5 − Li5.7 − Be4.8 − W4.7 − Cs4.6 − Rb3.8 − Pb3.5 − U3.3 − Th1.6 − Ta1.5 Sr < 0.1 − Ba < 0.1

+57.6 (12)

41

FP, amazonite Li-F-granites Turga

Li4.4 − Sn4.4 − Rb4.1 − Cs4 − Pb3.8 − U3.7 − Ta2.6 − Th2.2 − F2.1 − Be1.7 − Mo1.6 Sr < 0.1 − Ba < 0.1 − B0.7 − W0.9

+23.2 (13)

38

Khangilai

Li29.4 − Ta18.6 − F11.8 − W7.3 − Rb6.5 − Cs4.9 − Sn3.7 − Be1.7 Sr << 0.1 − Ba < 0.1 − U0.6 − Th0.8

+75.3 (10)

10, 11

Etyka

Sn100 − Ta31.1 − Pb10 − Rb8.8 − Li7.2 − W4.5 − F3.9 − U3.9 − Cs3 − Mo1.6 − Be1.1 Ba << 0.1 − Sr < 0.1 − Th0.3 − B0.6

+163 (13)

39

Note. Elemental formulas were obtained by the normalization of the contents of granitophile elements in a given granite variety to their clarke concentrations (B — 15, F — 800, Li — 40, Rb — 170, Cs — 5, Be — 3, Sr — 300, Ba — 800, Sn — 3, W — 1.5, Mo — 1, Pb — 20, Ta — 3.5, Th — 18, U — 3.5 ppm). CI is the concentration index of granitophile elements; it characterizes the excess (+) or deficit (–) of granitophile trace elements in a given granite variety relative to their clarke concentrations and is measured in the number of these clarkes: CI = CC1 + CC2 + CC3 + ... + CCn – n, where n is the number of granitophile elements used in the CI calculation. * After Kozlov (2000a).

the excess concentrations of rare metals (concentration indices (CI) for 13 granitophile trace elements) are 14.9 and 16.0 clarkes, respectively (Table 2). Thus, the initial high content of rare metals of the MP granites was not related to the differentiation of melts of parental magma chambers, and the differentiation of melts at its early stage (the MP granites of

the second group of intrusions with a Eu minimum) led to an insignificant increase in the contents of granitophile elements. As was shown earlier, the granites enriched in volatiles and trace elements were obviously generated from mantle alkalibasaltoid melts enriched in the same elements, which favored the formation of local crustal magma chambers of granite

V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

melts of rare-metal intrusions (Kozlov, 2000a; Kozlov and Efremov, 1999). The initial enrichment of mantle melts in granitophile volatiles and trace elements led to the intense magmatic differentiation of granite melts; as a result, ore-bearing leucogranite differentiates highly enriched in volatiles and trace elements were produced. For example, the Erzgebirge and Bohemian Massif rare-metal granites formed with the active participation of early intrusions of alkali-basaltoid melts, namely, massifs of durbachites (monzosyenites) highly enriched in granitophile trace elements (Tauson et al., 1979). As seen from the REE pattern of durbachites (Fig. 2, pattern D), they are the most enriched in LREE as compared with the Erzgebirge rare-metal granites, and their contents of HREE, starting from Tb, are close to those in the MP granites of the Erzgebirge early complex (OIC). Comparison of the REE patterns of durbachites from the Middle Czech Massif (Fig. 6, pattern D) with those of early monzodiorites from the Kulinda intrusion of the Kukul’bei complex (pattern 21) and MP granitoids from the Unda batholith complex in eastern Transbaikalia (pattern U) (Kozlov et al., 2003) shows that the durbachites almost lack a Eu minimum but have the highest contents of both LREE and HREE, exceeding their clarke concentrations in granites 1.7 and 1.5 times, respectively (Table 3). The Kulinda monzodiorites have higher LREE contents close to those of the durbachites and clarke concentrations of HREE, and the Unda granodiorites (widespread in eastern Transbaikalia) have clarke concentrations of LREE and ultralow contents of HREE (0.6 clarke). The REE patterns of rare-metal granites also bear information on their ore potential. The ore-bearing intrusive bodies of the Kukul’bei complex are composed of muscovite granites, which are either the dome facies (subfacies?) of the MP granites or the EIP-FP pegmatite-bearing granites (Kozlov and Svadkovskaya, 1977). The Khangilai intrusion with dome muscovite granites serves as a reference. Its Spokoinyi dome (Fig. 3, a, pattern 9) bears the Spokoininskoe greisen wolframite and accessory beryl deposit. Similar dome muscovite granites were recognized in the Zun-Undur, Durulgui, and Oldonda systems (Fig. 3, b, c, f, respectively). Comparison of the REE patterns of these rocks shows that muscovite granites from the Khangilai intrusion have the lowest contents of both LREE and HREE, a distinct Eu minimum (Fig. 3, a, pattern 9), and high contents of granitophile elements (>96 excess clarkes

39

Fig. 6. Chondrite-normalized REE patterns of the MP granodiorites from the Unda batholith complex (pattern U), eastern Transbaikalia, EP monzodiorites from the Kulinda intrusion (pattern 21), and EP monzosyenites (durbachites) from the Middle Czech Massif (pattern D). Designations follow Fig. 2. For the total REE contents of granitoids, see Table 3.

for 13 granitophile elements, Table 2, column 9). A similar REE pattern is observed for dome muscovite granites from the Durulgui massif, which bear the exhaust Dedovogorskoe quartz-wolframite deposit (Barabanov, 1975). The dome muscovite granites (Fig. 3, c, pattern 19) have low contents of both LREE and HREE and a distinct Eu minimum, and their CI for 13 granitophile elements is >170 clarkes (Table 2, column 19). In contrast to the REE patterns of muscovite granites bearing commercial mineralization, the REE patterns of dome muscovite granites from the Zun-Undur and Oldonda massifs (noncommercial Antonovogorskoe quartz-wolframite deposit) (Barabanov, 1975) show only a negligible decrease in REE contents (Fig. 3, b, f, patterns 15, 16, and 35) and much lower excess contents of granitophile elements — 64.5 and 26 clarkes, respectively (for 13 elements) (Table 2, columns 16 and 35). This evidences that the most productive mineralization is developed in the dome muscovite granites that are maximally differentiated; the main specific feature of their REE patterns is not a Eu minimum but a drastic decrease in the contents of all REE and an increase in the contents of

Table 3 REE distribution in Transbaikalian monzonitoids and clarke granodiorites Parameters of REE distribution; total contents are given in ppm

EP monzosyenites (Middle Czech massif)

EP monzodiorites (Kulinda intrusion)

MP granodiorites (Unda complex)

Clarke concentrations in granites, after Ovchinnikov (1990) 189.8

ΣREE

319.89

310.86

183.82

CC1

1.68

1.64

0.97

ΣLREE

274.08

283.4

165

CC2

1.73

1.79

1.04

ΣHREE

45.81

27.46

18.82

CC3

1.46

0.87

0.6

158.4

31.4

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V.D. Kozlov / Russian Geology and Geophysics 50 (2009) 29–42

granitophile elements (Table 1, total REE contents and CC1 values). A similar conclusion follows from comparison of the REE patterns of pegmatite-bearing muscovite granites (Fig. 3, c, pattern 20; d, 29 and 31; e, 25 and 26; Table 1). The pegmatite-bearing granites from the Bogov Utes massif hosting poor quartz-cassiterite deposit (Fig. 3, e, pattern 26) and the late muscovite leucogranites from the rare-metal pegmatite deposit described by Zagorskii and Kuznetsova (1990) (Fig. 3, d, pattern 31) actually bear mineralization. Both REE patterns are characterized by ultralow lanthanide contents. In contrast to the dome muscovite granites, the excess content of granitophile elements in the pegmatite-bearing leucogranites is as low as 13–28 clarkes (Table 2). In general, the REE patterns of dome and pegmatite-bearing muscovite granites are similar: The ore-bearing varieties show a drastic decrease in contents of REE, particularly LREE. The same conclusion follows from analysis of the REE patterns of amazonite Li-F-granites from the Kukul’bei complex. Figure 4 presents the REE patterns of amazonite granites from three massifs: Orlovka (Khangilai intrusion) (Kovalenko et al., 1999; Syritso et al., 2001), Turga leucogranite-amazonite, and Etyka amazonite (both in the Kukul’bei area) (patterns 10, 38, and 39, respectively). The figure also shows the REE patterns of leucogranites that were precursors of the amazonite granites of the Turga massif (pattern 37) and of the MP granites of the Soktui massif, Kukul’bei complex (pattern 36) (Kovalenko et al., 1999). As seen from the figure, the patterns of the final differentiates of the complex — amazonite granites — follow pattern 36. The REE patterns of the three massifs of amazonite granites differ drastically. The Turga ore-free granite varieties (pattern 38) are characterized by a moderate decrease in LREE contents, whereas the Etyka ones (pattern 39) show a drastic decrease in all REE. By this feature, the Etyka massif must be considered the most ore-bearing, which is confirmed by the elemental formula of its granites and the highest concentrations of their granitophile elements (CI = 163 clarkes for 13 granitophile elements, Table 2). As seen from Fig. 4, the REE pattern of leucogranites, precursors of amazonite granites of the Turga massif, has a deep Eu minimum. This is an almost single example of leucocratic nonrare-metal granites in the Kukul’bei complex whose low contents of granitophile elements were tentatively explained by the degassing of the latter (Kozlov and Svadkovskaya, 1977). The fact that these granites belong to the Kukul’bei complex is confirmed by the similarity of their REE pattern to that of the MP granites of the reference Soktui massif (patterns 36 and 37). Summarizing the data on the REE patterns of muscovite and amazonite granites from the Kukul’bei complex and their rare-metal ore potential, we have drawn the conclusion that the varieties with ultralow REE contents and the highest contents of trace and volatile granitophile elements are the most ore-producing. Probably, the drastic decrease in REE contents reflects the beginning of pneumatolith-hydrothermal process and separation of lanthanides with the first portions of postmagmatic fluids. The same is evidenced from the data

on the Erzgebirge quartz-topaz greisens (Štemprok et al., 2005). Among the considered intrusive systems of the Kukul’bei complex, the Sherlovaya Gora ultrarare-metal granites and quartz porphyry (ongonites) (Antipin et al., 1980) earlier studied by Troshin et al. (1983) show unusual REE patterns. The Sherlovaya Gora area is a famous ore district in Transbaikalia. Since 1721 (Barabanov, 1994), jewelry aquamarines and topazes have been mined from the granite dome greisens there. In the 1940–50s, rich cassiterite placers bearing greisens were exploited, and wolframite deposit was explored within the dome. In the 1930s, Academician S.S. Smirnov discovered a large cassiterite-sulfide-polymetallic deposit (which was nevertheless poor in Sn-ores (∼0.1%)) in quartz porphyry (ongonites). Its quarry exploitation was performed in the 1970s. The REE patterns of the Sherlovaya Gora ultrarare-metal leucogranites and ongonites (Table 2, CI = 38.2 and 57.6 clarkes, respectively) differ drastically from the above-considered ones of the Kukul’bei granites in showing higher contents of HREE and an ultradeep Eu minimum; the latter is deeper as compared with the REE pattern (Fig. 5, 36) of the MP granites of the Soktui massif and is the best pronounced in the REE pattern of the ongonites. That is, the REE patterns of the Sherlovaya Gora ultrarare-metal granites are similar to those of ultrarare-metal lithionite-zinnwaldite granites from the most ore-productive domes of the Erzgebirge intrusive system (Fig. 2). Comparison of these patterns (Figs. 2 and 5) shows that the Erzgebirge domes are also richer in HREE. Thus, the most productive rare-metal mineralization is developed in dome ultrarare-metal granites and leucogranites, which are highly enriched in volatiles and trace elements and have above-clarke contents of HREE (Y group elements). Medium contents of REE, especially HREE, are observed in ultrararemetal dike rocks of the Khangilai intrusion, which is correlated with its high ore potential. The summarized data on the relationship between the REE patterns of late differentiates of rare-metal intrusions and their ore potential are ambiguous. On one hand, the actually ore-bearing intrusion differentiates of the Kukul’bei complex (late muscovite and amazonite granites) have much lower contents of REE than the MP granites and the highest contents of granitophile elements and volatiles, including ore-forming ones. On the other hand, W-Sn mineralization is the most intensely developed in domes of late Li-F-leucogranites (including the Erzgebirge lithionite-zinnwaldite ones), which are the most enriched in both granitophile elements and HREE. These differentiates determined the high ore productivity of the Erzgebirge intrusive system as well as the Sherlovaya Gora intrusion in Transbaikalia. The difference between the muscovite and lithionite-zinnwaldite varieties of ultrarare-metal leucogranites seems to be due to the different compositions of their parental magmatic fluids. Judging from the muscovite contents in the ore-bearing muscovite granites (8–12%) (Kozlov, 2005a), their fluid phase was dominated by water; the dome muscovite granites had medium contents of F, and the pegmatite-bearing ones, low contents (Table 2). Most likely,

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the melts of amazonite granites also had high concentrations of water; in the Orlovka massif they are associated with widespread two-mica and muscovite granites (Beskin et al., 1994). In contrast to the Transbaikalian amazonite granites, the Sherlovaya Gora leucogranites and ongonites and the Erzgebirge late dome lithionite-zinnwaldite granites were dominated by F (5000–8000 ppm) (Kozlov, 2000a). At least, the comparison showed that the W-Sn rare-metal potential of the late muscovite differentiates of rare-metal intrusions is much lower than that of the leucogranite differentiates of rare-metal intrusions lacking or being poor in muscovite granites.

Conclusions 1. The same degree of enrichment of the Kukul’bei intrusive MP granites in trace granitophile elements independently of the presence or absence of a Eu minimum (indicator of the degree of magmatic differentiation) in their REE patterns evidences that the initial enrichment of the intrusions in these elements was not related to their magmatic differentiation. 2. The differentiation of most of Transbaikalian rare-metal granite intrusions is accompanied by a decrease in REE contents and some increase in Eu minimum in passing from MP biotite granites to late differentiates — dome and pegmatite-bearing muscovite leucogranites enriched in granitophile volatiles and trace elements and ultrarare-metal amazonite Li-F-granites. The REE patterns of muscovite and amazonite granites bearing pneumatolith-hydrothermal W-Sn-Ta or raremetal pegmatite mineralization show a drastic decrease in REE contents. 3. In contrast to most of granite intrusions, whose successive leucocratic differentiates obey the general rule of REE content decrease, the ore-bearing intrusions with MP rare-metal granites (Erzgebirge, Central Europe) often include domes of late ultrarare-metal lithionite-zinnwaldite Li-F-granites. They have ultrahigh contents of granitophile elements, volatiles, and HREE; it is these granites whose domes in the Erzgebirge bear the most productive Sn-W mineralization. In Transbaikalia, the dome leucogranites and ongonites of the Sherlovaya Gora Sn-W-Be-bearing intrusion, the most productive one in the region, belong to such differentiates of rare-metal intrusions. 4. The performed analysis of the REE patterns of ore-bearing rare-metal granites from the Kukul’bei complex confirm the earlier conclusion (Kozlov, 1985) on the low Sn-W–raremetal ore productivity of its intrusions. This work was supported by grants 03-05-65041 and 05-05-64052 from the Russian Foundation for Basic Research.

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Editorial responsibility: G.V. Polyakov