www.dmirs.wa.gov.au Geological Survey ofWestern Australia

Government of Western AustraliaDepartment of Mines, Industry Regulation and Safety

FEBRUARY 2020

ZIRCON FINGERPRINTING

1,2 1 1,2 3 4,2 5 6Yongjun Lu , Hugh Smithies , Michael Wingate , Noreen Evans , Cam McCuaig , David Champion , Michael Outhwaite1Geological Survey of Western Australia, 100 Plain Street, East Perth WA 6004, Australia

2Centre for Exploration Targeting and ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), School of Earth Sciences, The University of Western Australia, Crawley WA 6009, Australia3School of Earth and Planetary Science / John de Laeter Centre, Curtin University, Bentley WA 6105, Australia

4BHP, 125 St Georges Terrace, Perth WA 6000, Australia5Geoscience Australia, GPO Box 378, Canberra ACT 2601, Australia

6Model Earth Pty Ltd, Unit 2, 80 Colin Street, West Perth WA 6005, Australia

1. This work documents the first craton-wide study to systematically examine zircons from granitic rocks in the Archean Yilgarn Craton as potential metallogenic fertility indicators of Archean magmatic–hydrothermal systems. Fertile granitic rocks from the Calingiri Cu–Mo and Boddington Au–Cu–Mo deposits in the Yilgarn Craton show distinctly higher zircon Eu/Eu* values (>0.4) and amphibole-dominated fractionation in hydrous melts, similar to Phanerozoic fertile granitic rocks.

Summary

4. Archean granites typically do not get sufficiently hydrous to form large porphyry Cu–Mo systems, but occasionally they do, and zircon chemistry can help pinpoint these locations.

5. For use in exploration, at least 50 zircons per sample should be analysed. After filtering results that indicate contaminated and altered grains, if more than 10 out of 20 analyses indicate zircon Eu/Eu* >0.4, the sampled rock may be classified as a fertile granite.

2. Barren granitic rocks from across the Yilgarn Craton display lower zircon Eu/Eu* values (<0.4) and plagioclase-dominated fractionation, indicating their derivation from relatively dry melts.

3. These results suggest that zircon Eu anomalies and trace element ratios can be used to distinguish fertile from barren granitic rocks in Archean and Phanerozoic terranes, providing an effective geochemical exploration tool to assess the metallogenic fertility of granitic rocks over geological time.

References

Lu, Y-J, Loucks, RR, Fiorentini, M, McCuaig, TC, Evans, NJ, Yang, Z-M, Hou, Z-Q, Kirkland, CL, Parra-Avila, LA and Kobussen, A 2016, Zircon Compositions as a Pathfinder for Porphyry Cu ± Mo ± Au Deposits, in Tectonics and Metallogeny of the Tethyan Orogenic Belt edited by Richards: Society of Economic Geologists: Special Publication 19, p. 329–347.

Ballard, JR, Palin, MJ and Campbell, IH 2002, Relative oxidation states of magmas inferred from Ce(IV)/Ce(III) in zircon: application to porphyry copper deposits of northern Chile: Contributions to Mineralogy and Petrology, v. 144, no. 3, p. 347–364, doi:10.1007/s00410-002-0402-5.

McCuaig, TC, Behn, M, Stein, H, Hagemann, SG, McNaughton, NJ, Cassidy, KF, Champion, D and Wyborn, L 2001, The Boddington Gold Mine: a new style of Archaean Au–Cu deposit, in International Archaean Symposium: Extended Abstracts edited by KF Cassidy, JM Dunphy and MJ Van Kranendonk: Australian Geological Survey Organisation, Record 2001/37, p. 453–455.

Outhwaite, MD 2018, Metamorphosed Mesoarchean Cu–Mo–Ag mineralization: evidence from the Calingiri deposits, southwest Yilgarn Craton: Geological Survey of Western Australia, Report 183, 208p.

Lu, Y, Smithies, RH, Wingate, MTD, Evans, NJ, McCuaig, TC, Champion, DC and Outhwaite, M 2019, Zircon fingerprinting of magmatic–hydrothermal systems in the Archean Yilgarn Craton: Geological Survey of Western Australia, Report 197, 22p.

For more information, contact:Yongjun Lu (yongjun.lu@dmirs.wa.gov.au)

Abbreviations: Amph, amphibole; Ap, apatite; Grt, garnet; Plg, plagioclase; TTG, tonalite–trondhjemite–granodiorite; Ttn, titanite; Zrc, zircon

Geochemistrysample

Zirconsample

Potassic high-Sr/Y granitePotassic low-Sr/Y graniteSodic high-Sr/Y graniteSodic low-Sr/Y granite

126°E122°E118°E114°E

28°S

32°S

300 km

INDIAN

OCEAN

PERTH

MurchisonMurchison

YYYouanmiouanmiouanmi

South WSouth WSouth Westestest

Kalg

oo

rlieK

alg

oo

rlieK

alg

oo

rlieK

alg

oo

rlie

YamarnaYamarnaYamarna

BurtvilleBurtvilleBurtville

KurnalpiKurnalpiKurnalpi

NarryerNarryerNarryer

SouthernSouthernCrossCross

Calingiri

Boddington

Figure 1. Whole-rock and zircon sample locations superimposed on a gravity image of the Yilgarn Craton, labelled by terrane (from Lu et al., 2019). The Calingiri Cu–Mo–Ag mineralization is hosted by c. 3 Ga granitic gneiss, and was recently discovered in the southwest Yilgarn Craton. It has a combined Indicated and Inferred resource of 529 Mt at 0.27% Cu (1.4 Mt contained Cu) and its grade tonnage profiles, metal distributions and hydrothermal alteration characteristics are comparable to those of Phanerozoic porphyry Cu–Mo deposits (Outhwaite, 2018). The Boddington deposit is a structurally-controlled, intrusion-related Au–Cu deposit with over 26 Moz of Au. Mineralization at the Boddington deposit formed at 2700 Ma and 2615 Ma (McCuaig et al., 2001)

80°N

40°N

0°60°W120°W

80°S

40°S

60°E 120°E

Batu HijauBatu HijauBatu Hijau

Tampakan

DexingDexingDexing

Nannihu&YuchilingNannihu&YuchilingNannihu&Yuchiling

Qulong and JiamaQulong and JiamaQulong and JiamaSar CheshmehSar CheshmehSar Cheshmeh

SungunSungunSungun

Kadoona and HawkinsKadoona and HawkinsKadoona and Hawkins

LucerneLucerneLucerne

YellowstoneYellowstoneYellowstone

BishopBishopBishop Bandelier Bandelier Bandelier

Figure 2. Global relief map showing the worldwide distribution of porphyry Cu deposits, and selected Phanerozoic fertile and infertile

magmatic suites (from Lu et al., 2016)

0°

Porphyry Cu deposits

Fertile suiteInfertile suite

0

10

20

30

40 Barren (197)

Archean granitic rocks

Fertile (227)

Phanerozoic granitic rocks

Fertile (337)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Nu

mb

er

of

zirc

on

s

Zircon (Eu/Eu*)

Infertile (93)

Figure 3. Probability density diagram of zircon Eu anomaly (Eu/Eu*) ratios for fertile and barren Archean granitic rocks in the Yilgarn Craton compared with fertile and infertile granitic rocks of Phanerozoic age from Lu et al. (2016). The vertical dashed line (Eu/Eu* = 0.4) is the fertility threshold from Ballard et al. (2002)

12

3

6

7

abbr.

0

2

4

6

8

10

12

14

0.0 0.2 0.4 0.6 0.8 1.0 1.2

205930: Fertile Calingiri

3010 Ma syn-ore monzogranitic gneiss

(n = 30, 60% >0.4)

0

1

2

3

4

5

6

7

8

9

10

0.1 0.3 0.5 0.7 0.9 1.1 1.3

205931: Fertile Calingiri

3010 Ma syn-ore syenogranitic gneiss(n = 21, 76% >0.4)

0

5

10

15

20

25

0.1 0.3 0.5 0.7 0.9 1.1 1.3

BODD-3: Fertile Boddington2700 Ma syn-ore dacite

(n = 58, 95% >0.4)

0

1

2

3

4

5

6

7

0.15 0.25 0.35 0.45 0.55 0.65 0.75 0.85

BODD-5: Fertile Boddington2700 Ma syn-ore diorite

(n = 62, 53% >0.4)

0

5

10

15

20

25

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

BODD-2: Fertile Boddington2700 Ma syn-ore diorite

(n = 56, 86% >0.4)

Nu

mb

er

Nu

mb

er

Zircon (Eu/Eu*)

Re

lati

ve

pro

ba

bil

ity

Zircon (Eu/Eu*)

Nu

mb

er

Nu

mb

er

Zircon (Eu/Eu*)

Re

lati

ve

pro

ba

bil

ity

Zircon (Eu/Eu*)

Nu

mb

er

Zircon (Eu/Eu*)

Calingiri

Figure 4. Probability density diagrams of zircon Eu/Eu* ratios for individual fertile granitic samples from the Calingiri and Boddington deposits in the Yilgarn Craton. The vertical dashed line (Eu/Eu* = 0.4) is the fertility threshold from Ballard et al. (2002)

Boddington

Rela

tive p

rob

ab

ilit

y

Rela

tive p

rob

ab

ilit

y

Re

lati

ve

pro

ba

bil

ity

0

2

4

6

8

10

12

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

183146:Barren 2681 Ma Bt–Hbltonalite,Yamarna Terrane

(n = 30, 10% >0.4)

0

2

4

6

8

10

12

14

0.0 0.1 0.2 0.3 0.4 0.5

Nu

mb

er

Nu

mb

er

Zircon (Eu/Eu*)

118951: Barren 2658 Ma Hbl–Btgranodiorite, Kurnalpi Terrane

(n = 38, 0% >0.4)

0

1

2

3

4

5

6

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Rela

tive p

rob

ab

ilit

y

Rela

tive p

rob

ab

ilit

y

Zircon (Eu/Eu*)

179450: Barren 2832 Ma

(n = 17, 12% >0.4)

0

1

2

3

4

5

6

7

8

9

0.15 0.25 0.35 0.45 0.55 0.65

Nu

mb

er

Nu

mb

er

Zircon (Eu/Eu*)

185923: Barren 2724 Ma Bt–Hbl

tonalite gneiss, Murchison Domain(n = 17, 6% >0.4)

0

1

2

3

4

5

6

7

0.15 0.25 0.35 0.45 0.55 0.65 0.75Zircon (Eu/Eu*)

(n = 13, 38% >0.4)

0

1

2

3

4

5

6

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Nu

mb

er

Nu

mb

er

Zircon (Eu/Eu*)

101381: Barren 2675 Ma Bt–Hblmonzogranite, Kurnalpi Terrane

(n = 11, 27% >0.4)

Zircon (Eu/Eu*)

0

1

2

3

4

5

6

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Nu

mb

er

Zircon (Eu/Eu*)

207630:Barren

Murchison Domain(n = 32, 0% >0.4)

Potassic low-Sr/Ygranite

Sodic high-Sr/Ygranite (TTG)

Sodic low-Sr/Ygranite

Sodic low-Sr/Ygranite

Sodic low-Sr/Ygranite

Sodic low-Sr/Ygranite

Sodic high-Sr/Ygranite (TTG)

Figure 5. Probability density diagrams of zircon Eu/Eu* ratios for individual barren granitic samples from across the Yilgarn Craton. Only samples yielding more than 10 primary zircon analyses are plotted. The vertical dashed line (Eu/Eu* = 0.4) is the fertility threshold from Ballard et al. (2002)

Re

lati

ve

pro

ba

bil

ity

Rela

tive p

rob

ab

ilit

yR

ela

tive p

rob

ab

ilit

y

Rela

tive p

rob

ab

ilit

y

Rela

tive p

rob

ab

ilit

y

185928: Barren 2733 Ma Bt–Hblmetatonalite, Murchison Domain2626 Ma monzogranite, metatonalite, Yarmana Terrane

Figure 6. Partition coefficients of rare earth elements between mineral and melt. Data sources are listed in Lu et al. (2019). Among the minerals commonly crystallized before or during zircon saturation in granitic rocks, plagioclase is the only one that preferentially incorporates Eu, depleting the melt in Eu

0.001

0.01

0.1

1

10

100

1000

Titanite

Apatite

Zircon

Garnet

Amphibole

Plagioclase

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

D (

min

era

l/m

elt

)

Nd

Boddington 2700 Ma syn-ore dacite (BODD-3)

Boddington 2700 Ma syn-ore diorite (BODD-2)

Boddington 2700 Ma syn-ore diorite (BODD-5)

amphibole:apatite of 99.8 : 0.2

plagioclase:apatite of 98.7 : 1.3

AmphAp

Ttn

Zrc

Grt

Plg:Ap(98.7 : 1.3)

Plg

10%

50%

0.2%1%

90%

50%70%50%

30%

0.25%0.30%

0.1%

1.6%1.4%

70%

60%

Plg:Ap(98.7 : 1.3)

60%50%40%Boddington 2613 Ma granite (BODD-1)

a) a)

b)

c)

Calingiri 3010 Ma syn-ore syenogranitic gneiss (205931)

Calingiri 3010 Ma syn-ore monzogranitic gneiss (205930)

AmphAp

Ttn

Zrc

Grt

Plg:Ap (98.7 : 1.3)

2658 Ma Hbl–Bt granodiorite, Kurnalpi Terrane (118951, Sr/Y = 3, Eu/Eu* = 0.51)

2832 Ma metatonalite, Yarmana Terrane (179450, Sr/Y = 2, Eu/Eu* = 0.68)

2724 Ma Bt–Hbl tonalite gneiss, Murchison Domain (185923, Sr/Y = 13, Eu/Eu* = 0.90)

2733 Ma Bt–Hbl metatonalite, Murchison Domain (185928, Sr/Y = 25, Eu/Eu* = 0.81)

Potassic low Sr/Y 2626 Ma monzogranite, Murchison Domain (207630, Sr/Y = 3, Eu/Eu* = 0.26)

TTG 2675 Ma Bt–Hbl monzogranite, Kurnalpi Terrane (101381, Sr/Y = 58)

TTG 2681 Ma Bt–Hbl tonalite, Yamarna Terrane (183146, Sr/Y = 45, Eu/Eu* = 0.95)

AmphAp

TT

GS

od

ic lo

w-S

r/Y

gra

nitic

rocks

Ttn

Zrc

Grt

Plg:Ap (98.7 : 1.3)

0.6

0.6

0.6

0.8

0.8

0.8

0.4

0.4

0.4

0.2

0.2

0.2

0 10 20 30 40

Zircon (Yb/Gd)

0.0

Zir

co

n (

Eu

/Eu

*)Z

irco

n (

Eu

/Eu

*)Z

irco

n (

Eu

/Eu

*)

b)

c)

Fertile

Fertile

Barren

Plg

Plg

Figure 7. Zircon Eu/Eu* vs Yb/Gd ratios for fertile and barren granitic rocks from the Yilgarn Craton, showing within-sample variations. Also shown are Rayleigh fractionation modelling curves of various minerals, with the numbers indicating percentage of crystallization of the related mineral or mineral assemblage

of magmatic–hydrothermal systems in the Archean Yilgarn Craton