Characteristics of zircon in the Khalzan Burgedei Zr-Nb-REE deposit

Nergui SARANGUA

Yasushi Watanabe

Akita University Faculty of International Resource Sciences

Mongolia Mineral Exploration Roundup 2015, Ulaanbaatar, Mongolia

METALLOGENIC BELT AND MINERAL DEPOSIT MAPS FOR NORTHEAST ASIA

KhZ

KZ

KhZ – Khalzan Burged (396-423 Ma)BOM- Bugseingol-Ovormarat (396-400 Ma)KZ- Aryskan (390-400 Ma)

AI

Zsh

AT

UT

KA

Devonian-Early Carboniferous BOM

Late Carboniferous- Middle Triassic

AI – Angara Ilim (260-200 Ma)Zsh- ZashikhinskyAT – Altay (219 Ma)

UT- Ulug Tanzek (231-228 Ma)

Late Triassic- Early Jurassic

KA- Karasug ( 112-122 Ma)

Middle Jurassic- Early Cretaceous

REE deposits

• The Khalzan Burgedei peralkaline complex is located in western Mongolia, in a N-S trending paleo-rift zone.

• In 1984, the V.I. KOVALENKO discovered the Khaldzan Buregtey rare-metal mineralization in the complex.

• Prognostic resources of category P2 calculated (1989-1990) 163.8 million tones.

INTRODUCTION OF KHALZAN BURGEDEI REE DEPOSIT

Average grade Resources

Ta2O5 0.011% 17,884t

Nb2O5 0.2% 335,346t

Zr2O5 1.46% 2,402,863t

REE 0.3% 489,952t

• Field observation • Drill core observation • Petrography and Geochemistry (optical microscopy,

ICPMS, SEM-EDS, EPMA)

METHODOLOGY

GENERAL GEOLOGY OF THE KHALZAN BURGEDEI COMPLEX

Quartz syenite

Metasomatite granite

Quartz richgranite

Ear

lies

t to

yo

un

ge

st

GEOLOGY OF THE KHALZAN BURGEDEI DEPOSIT

L-5362120

BTDDH-11

Quartz rich

• In the surface rocks and drill holes underwent intense hydrothermal alteration accompanied with albitization, potassic alteration and Zr-Nb-REE mineralization.

Grade (ppm) Average grade (ppm)

REE 628.88 - 4,110.93 1900

LREE 460.61 - 3,899.96 1360

HREE 78.60 - 434.0 500

Y 133.0 - 743.0 310

Zr 516.0 - 14,150.0 2500

Nb 139.0 - 915.0 400

Geochemistry of hole number BTTDH11

Metasomatite Granite: Medium-coarse grained quartz-amphibole, feldspar granite

Syenite: Quartz-bearing coarse grained syenite with amphibole and feldspar

Metasomatite Granite: Coarse grained granite with feldspar, amphibole and quartzSyenite: Quartz-bearing coarse grained syenite with amphibole and feldspar

Pegmatitie: Pegmatite of feldspar, quartz, zircon, Amphibole replaced by chlorite

Pegmatitie: Pegmatite of feldspar, quartz, zircon, Amphibole replaced by chlorite

Granite: Medium-coarse grained quartz-amphibole, feldspar granite

Quartz granite: Medium-fine grained rounded quartz, amphibole granite.

Metasomatite Granite: Medium-coarse grained quartz-amphibole, feldspar granite

Metasomatite Granite: Medium-coarse grained quartz-amphibole, feldspar granite

0 2000 4000 6000 8000 10000 12000 14000 160000

100200300400500600700800900

1000

Zr (ppm)

Nb (p

pm)

0 2000 4000 6000 8000 10000 12000 14000 160000

5001000150020002500300035004000

Zr (ppm)

REE

(ppm

)

0 2000 4000 6000 8000 10000 12000 14000 160000

500

1000

1500

2000

2500

3000

Zr (ppm)

LREE

0 2000 4000 6000 8000 10000 12000 14000 160000

200

400

600

800

1000

1200

1400

Zr (ppm)

HREE

(ppm

)

Geochemistry

• REE is more abundant in Quartz rich Granite than quartz syenite and metasomatized granite.

• Pegmatite is most enriched in HREE.

Geochemistry

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Y10

100

1000

10000

Normalized after Chondrite (Mc Donough and Sun, 1995

Quartz syenite Metasomatite granite Quartz rich Granite Pegmatite

Rock/Chondrite

TYPE-1. Euhedral crystals, with zoning, intergrown with, or enclosing REE mineral

Occurrence of zircon

89.2 m – P22

Zircon in Metasomatite granite

82.9 m 82.9 m– P25-1

Zircon in Metasomatite granite

99.5 m – P6-4

87.5 m – P14-1 157.4 m – P6-1

Zircon in Quartz rich Granite

216.5 m – P4

Zircon in Metasomatite granite

85.7 m – P14-199.5 m – P15-1

TYPE-2. Anhedral zircon

Zircon in pegmatite

282.0 m

Point 264-20-2-a 264-20-2-b 264-20-2-c 264-22-3-a 264-22-3-b 264-22-3-c 264-22-3-d 265-1-a 265-1-b 265-6-2-a 265-6-2-b 265-15-1-a 265-15-1-b

SiO2 32.057 32.541 31.943 32.751 27.091 23.449 31.148 32.49 32.916 30.647 45.233 33.204 30.288

ZrO2 56.648 57.564 56.459 60.437 52.499 43.206 57.457 52.272 57.444 55.034 56.54 61.928 58.772

HfO2 2.037 2.09 2.19 2.232 1.998 1.642 2.369 2.415 2.803 1.978 2.78 3.121 3.076

Y2O3 4.08 4.184 3.964 2.18 3.859 4.446 3.375 3.538 2.451 3.509 0.341 0.902 0.838

Al2O3 0.002 0.008 0 0.017 0.332 0.396 0.046 0.894 0.264 0.104 0.18 0.292 0.265

FeO 0 0 0 0 0 0 0.008 0 0 0 0 0 0

MgO 0 0 0 0.001 0 0.006 0.717 0 0 0 0 0 0.004

CaO 0.081 0.088 0.094 0.032 1.004 1.916 0.0967 0.069 0.052 0.028 0.137 0.226 0.27

Total 95.303 96.738 94.977 97.997 86.866 75.065 95.159 92.155 96.609 92.047 105.634 99.866 93.6

Numbers of ions on the basis of 16O

Si 4.0345 4.0293 4.0362 4.0529 3.7714 3.7320 3.9217 4.1185 4.1031 4.0161 4.8729 4.0462 3.9651

Zr+Hf 3.5497 3.5495 3.5577 3.7258 3.6432 3.4277 3.6127 3.3185 3.5914 3.5907 3.0556 3.7884 3.8667

Y 0.5465 0.5514 0.5331 0.2871 0.5718 0.7531 0.4523 0.4773 0.3252 0.4894 0.0391 0.1170 0.1168

Al 0.0006 0.0023 0.0000 0.0050 0.1089 0.1486 0.0137 0.2671 0.0776 0.0321 0.0457 0.0839 0.0818

Fe 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0008 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Mg 0.0000 0.0000 0.0000 0.0002 0.0000 0.0014 0.1346 0.0000 0.0000 0.0000 0.0000 0.0000 0.0008

Ca 0.0109 0.0117 0.0127 0.0042 0.1498 0.3267 0.0967 0.0094 0.0069 0.0039 0.0158 0.0295 0.0379

Total 4.1077 4.1150 4.1035 4.0223 4.4737 4.6575 4.3108 4.1185 4.1031 4.1162 3.1562 4.0188 4.1039

Zircon in the Metasomatite granite (Type 1 and Type 2)

Composition of zircon by EPMA

Zircon in the Quartz rich Granite (Type 1)

Point 272-4-2-a 272-4-2-b 272-4-2-c 272-4-2-d 272-4-2-e 272-5-1-a 272-5-1-b 272-5-1-c 272-5-1-d 272-17-1-a 272-17-1-b

SiO2 35.057 35.474 35.088 35.198 34.758 35.498 34.652 35.146 35.133 27.663 33.993

ZrO2 62.748 61.69 63.617 61.721 61.88 62.748 61.591 62.97 62.721 50.93 61.221

HfO2 3.303 3.96 3.772 3.431 3.864 3.381 3.456 3.233 3.649 2.068 3.108

Y2O3 0.236 0.103 0 0.188 0.539 0.027 0 0.003 0 3.014 1.18

Al2O3 0.225 0.23 0.085 0.183 0.228 0.161 0.155 0.154 0.162 0.481 0.209

FeO 0 0 0 0 0 0 0 0 0 0 0

MgO 0 0.001 0 0.005 0 0 0 0 0.004 0.04 0

CaO 0.1 0.099 0.074 0.07 0.132 0.072 0.081 0.078 0.086 1.899 0.163

Total 102.44 102.571 103.107 101.736 101.863 102.83 101.016 102.445 102.62 86.169 100.293

Numbers of ions on the basis of 16O

Si 4.1711 4.2213 4.1662 4.2160 4.1540 4.2131 4.2009 4.1908 4.1891 3.8560 4.1121

Zr+Hf 3.7527 3.7141 3.8112 3.7223 3.7380 3.7460 3.7606 3.7714 3.7709 3.5441 3.7187

Y 0.0299 0.0130 0.0000 0.0240 0.0686 0.0034 0.0000 0.0004 0.0000 0.4472 0.1519

Al 0.0631 0.0645 0.0238 0.0517 0.0642 0.0450 0.0443 0.0433 0.0455 0.1580 0.0596

Fe 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Mg 0.0000 0.0002 0.0000 0.0009 0.0000 0.0000 0.0000 0.0000 0.0007 0.0083 0.0000

Ca 0.0127 0.0126 0.0094 0.0090 0.0169 0.0092 0.0105 0.0100 0.0110 0.2836 0.0211

Total 3.8585 3.8045 3.8444 3.8078 3.8877 3.8036 3.8154 3.8251 3.8282 4.4412 3.9513

Composition of zircon by EPMA

1. The Khalzan Burgedei peralkaline complex of the studied area consist of quartz syenite, metasomatized granite and quartz rich granite. Ore bodies consist of metasomatized granite and quartz rich granite.

2. At least two types zircon of are recognized in these intrusive.

Euhedral zircon (Magmatic and Metasomatic zircon)

Anhedral zircon (Metasomatic zircon)

3. The major HREE mineralization is represented by zircon, because zircon hosts a few wt.% of Yittrium. The zircon in the granite contain 0-3.0 wt.% Y, and zircon in the metasomatite granite contains 0.3-4.4 wt.% Y. Generally zircon in the metasomatized granite contain more Y. Some zircons contain Ca 0.07-1.9 wt.% Ca and 0.25-0.40 wt.% Na.

4. The chondrite normalized REE patterns show that the LREE concentration increase from Quartz syenite to Quartz rich granite. Pegmatite is most enriched in HREE, followed by quartz rich granite due to high concentration of zircon.

5. Weak correlation observed between Zr and Nb contents in the rocks. A similar correlation found between Zr and HREE. Zr and LREE concentration are poorly correlated.

SUMMARY

Thank you for your attention

Akita University Faculty of International Resource Sciences