Mineral Systems along the
southern margin of the Gawler
Range Volcanics
Northern Eyre Peninsula, South Australia
15th April, 2015
Ben Nicolson, Stacey McAvaney
www.statedevelopment.sa.gov.au
TRENDS:
Olympic Domain
Cu-Au-U
(Wallaroo Gp, Hiltaba
granites)
Spencer Domain
Cu, Pb, Zn,
Ag, Au ± Co, Ni
Archean Granite, schist,
Moonabie/Pandurra
Cleve/Coulta Domain
Pb-Zn-Ag, to Ag-Pb
Mn, Fe
Hutchison Gp schist
dolomite marble.
Sleaford granites
Nuyts Domain
Au-Ag (± Cu, Mo, PGE)
St Peters Suite granites,
abundant Hiltaba granite
Department of State Development
Metals Occurrences of the Northern Eyre Peninsula
2
TRENDS:
Olympic Domain
Cu-Au-U
(Wallaroo Gp, Hiltaba
granites)
Spencer Domain
Cu, Pb, Zn,
Ag, Au ± Co, Ni
Archean Granite, schist,
Moonabie/Pandurra
Cleve/Coulta Domain
Pb-Zn-Ag, to Ag-Pb
Mn, Fe
Hutchison Gp schist
dolomite marble.
Sleaford granites
Nuyts Domain
Au-Ag (± Cu, Mo, PGE)
St Peters Suite granites,
abundant Hiltaba granite
Department of State Development
Metals Occurrences of the Northern Eyre Peninsula
3
TRENDS:
Olympic Domain
Cu-Au-U
(Wallaroo Gp, Hiltaba
granites)
Spencer Domain
Cu, Pb, Zn,
Ag, Au ± Co, Ni
Archean Granite, schist,
Moonabie/Pandurra
Cleve/Coulta Domain
Pb-Zn-Ag, to Ag-Pb
Mn, Fe
Hutchison Gp schist
dolomite marble.
Sleaford granites
Nuyts Domain
Au-Ag (± Cu, Mo, PGE)
St Peters Suite granites,
abundant Hiltaba granite
Department of State Development
Metals Occurrences of the Northern Eyre Peninsula
4
TRENDS:
Olympic Domain
Cu-Au-U
(Wallaroo Gp, Hiltaba
granites)
Spencer Domain
Cu, Pb, Zn,
Ag, Au ± Co, Ni
Archean Granite, schist,
Moonabie/Pandurra
Cleve/Coulta Domain
Pb-Zn-Ag, to Ag-Pb
Mn, Fe
Hutchison Gp schist
dolomite marble.
Sleaford granites
Nuyts Domain
Au-Ag (± Cu, Mo, PGE)
St Peters Suite granites,
abundant Hiltaba granite
Department of State Development
Metals Occurrences of the Northern Eyre Peninsula
5
TRENDS:
Olympic Domain
Cu-Au-U
(Wallaroo Gp, Hiltaba
granites)
Spencer Domain
Cu, Pb, Zn,
Ag, Au ± Co, Ni
Archean Granite, schist,
Moonabie/Pandurra
Cleve/Coulta Domain
Pb-Zn-Ag, to Ag-Pb
Mn, Fe
Hutchison Gp schist
dolomite marble.
Sleaford granites
Nuyts Domain
Au-Ag (± Cu, Mo, PGE)
St Peters Suite granites,
abundant Hiltaba granite
Department of State Development
Metals Occurrences of the Northern Eyre Peninsula
6
Olympic –
Spencer
Domains
Low-sulfidation Veins:
3 Locations with
CRT, HBX, Banding
± Au-Ag
Sericite, Quartz,
Tourmaline, Albite
alteration assoc with
Roopena Fault –
Hiltaba Granite
mineralised trend
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Schematic
Alteration Zoning
Regional Examples:
23-Mile Quartz Quarry
Hydrothermal Mill Breccia
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Colloform (crustiform) banding
Multi-episodic
hydrothermal breccia,
cockade
Coarse Bladed Carbonate
Replacement Texture (BCRT)
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Parkinson Dam Au-Ag
198-199m:
23.19 g/t Au
46 g/t Ag
201 ppm Pb
1045 ppm Zn 68 ppm Cu
198.9m
Au-Ag Electrum
Fineness ~500
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169-170m:
9.05 g/t Au
79 g/t Ag
292 ppm Pb
2329 ppm Zn
93 ppm Cu Phengite-clay alteration (HyLogger)
180-181m:
105.3 g/t Au
449 g/t Ag
405 ppm Pb
2994 ppm Zn
161 ppm Cu
(8 ppm As)
(1.32 ppm Sb)
169.2m
180.9m
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Assay Data Courtesy of Tasman Resources
Low-Sulfidation Epithermal Model
Main mechanism causing
mineralisation is boiling of
ascending fluids
Vertical Zonation of metals
Vein textures relate to depth
of formation (vectors)
23-Mile Quartz
Quarry
Parkinson
Dam
Alteration dominated by
clays-silica-pyrite
Fluids dominated by
meteoric water with some
magmatic (metals?) input
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Cleve &
Coulta
Domains
Hutchison Gp:
Amphibolite to
granulite facies
metamorphism
(700oC & 7kbar)
Dolomite marble,
schists & gneisses,
Kimban granites.
Sleaford complex.
Menninnie & Paris
mineralised centres
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11
Menninnie Dam (most data)
Calc-silicate alteration dated
1710 Ma. Similar calc-silicate alt’n
Pb-Zn mineralisation dated 1710
Ma at 17 Bore, near Tarcoola.
/ 204Pb
Dominated by Upper Crustal
Source
Orogene
207Pb
Fluids and Metals
Sources
Mantle
Lower Crust
(Reid et al, 2009)
Pegmatite veins dated at 1710Ma
(Fanning 1984)
206Pb
/ 204Pb
Roache (1996)
Kimban age deformation,
Pb derived from Hiltaba Gt and
calc-silicate alteration and related
Hutchison Gp sediments
Meteoric water dominant but mixed mineralisation through Cleve-Coulta
Domains
meteoric-magmatic source (Roache 1996)
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12
Southern
GRV Margin
Area
Area &
comparison
Setting
Analogy
Imiter
district at
map scale
Imiter
Epithermal
Ag Deposit,
Morocco:
>8000T Ag
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Exploration Vectors
Epithermal / Hydrothermal
Targets
Imiter, Morocco
(>8000T Ag)
Rheology Contrasts
Extensional: normal faults
(7km)
Alteration –
Argillic + silicification
High grade small target size
= subdued geophysics
response
Department of State Development
Cheilletz, 2002.
Acanthite (Ag2S)
and native Ag,
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Imiter, Morocco
Exploration Vectors
Epithermal Targets
N
Drillholes
Upper V ~ V ~
V
GRV V ~ V ~
S Most major fluid conduits are often
Major Controlling
Structure (e.g. Uno Geochemical Anomalies buried (= preservation)
But outbound of Major
F. Buried/blind)
Small geochemical anomalies are
controlling structures
V ~ V ~ V ~ V ~ V ~ V ~ V ~ V ~
V ~ V ~ V ~ V ~ V ~ V ~ V ~
~ V ~ V ~
V
~
Lower GRV
Rhyolite
Dykes
schists
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Southern GRV Margin
Are there bounding Faults?
Ag, Pb
often peripheral (smoke) to the main
ore zones (fire!), but are often
insigificant
Ore/controlling structures usually
normal, and may dip into basin and
anomalism; (targeting needs to
consider this)
Does Upper GRV largely cover lower
GRV - and related mineralisation?
Conclusion:
Need to drill from within covered 15
areas
Concluding remarks
Southern margin of the GRV in the northern Eyre peninsula is
prospective for a number of reasons.
1) Heat source (the GRV event)
2) Metals source in basement rocks
3) Water/fluid source in meteoric water (peperites attest to
surface waters)
• Ingredients are there, but focus needs to define the major fluid
conduits which may be controlling/bounding faults to GRV units
• Most likely conduits may well be buried beneath the
voluminous GRV units
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Department of State Development
References
Cheilletz A., Levresse G., Gasquet D., Azizi-Samir M. R., Zyadi, R., Archibald D. R., Farrar E. 2002. The giant Imiter silver
deposit: Neoproterozoic epithermal mineralization in the Anti-Atlas, Morocco. Mineralium Deposita 37: 772–781
Buchanan, L. J. 1981. Precious metal deposits associated with volcanic environments in the southwest., in Dickinson,
W.R. And Payne, W. D. editorsRelationships of tectonics to ore deposits in the southern Cordillera. Arizona Geological
Society Digest. v. XIV, p 237-262.
Fanning, M. 1984. Rb-Sr geochronology of a pegmatite intrusive into the Kalinjala Mylonite Zone. Amdel report GS.
6102/84 (unpublished).
Reid, A., Flint, R. Maas, R., Howards, K., Belousova, E. 2009. Geochronological and isotopic constraints on
Palaeoproterozoic skarn base metal mineralisation in the central Gawler Craton, South Australia. Ore Geology
Reviews 36 (2009) 350–362.
Roache, M. 1996. Menninnie Dam Zn-Pb-Ag deposit, Eyre Peninsula, South Australia. PhD thesis. University of
Tasmania.
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Departmf State Development
Contact
Department of State Development
Geological Survey of South Australia
Level 4, 101 Grenfell St
Adelaide, South Australia 5000
GPO Box 320
Adelaide, South Australia 5001
T: +61 8 8226 3821
E: [email protected]
www.statedevelopment.sa.gov.au