Post on 12-Oct-2020
Australian Government
Geoscience Australia
Zinc-copper-lead metallogeny of the eastern Arunta
David L Huston1, Kelvin Hussey2
and Max Frater3
1Geoscience Australia2Arafura Resources NL (formerly Northern Territory Geological Survey)
3Northern Territory Geological Survey
Geoscience AustraliaNAP-wrap 2006
Acknowledgments
Jon Claoué-Long
Shen-Su Sun
Tim Munson
Roland Maas
Sue Golding
Colleagues at GA and NTGS
Geoscience Australia
SignificantZn-Cu-Pb(Ag-Au)
Mineralisationrestricted to:
(1) SE Aileron Province (1810-1800 Ma &
1765 Ma)
(2) Warumpi Province (1620-1610 Ma)
Geoscience Australia
Zn-Cu & Cu-Au – Arunta-Tennant-Tanami
StrangwaysStokes Yard, UlpurutaOonagalabi
Jervois
Home of BullionMt Hardy
White’s Yard
Silver King
Johnnies
TennantCreek
Rover
WA NT NT
Strangways RangeWarumpi ProvinceGeoscience Australia
Zn-Cu & Cu-Au prospects – Strangways Range
Geoscience AustraliaGeoscience Australia
Zn-Cu & Cu-Au prospects – Strangways Range
Type Element assemblage
Host Alteration assemblages
Age (Ma)
Origin
Utnalanama Zn-Pb-Cu(Ag-Au-Bi-Cd)
Marble and calc-silicate after marble.
Qz-crd±opxrock > massive amp±spn±cpx rock
1810-1800
VHMS
Oonagalabi Zn-Cu-Pb(Ag-Au-Bi)
Marble →calc-silicate → massive anthophyllite.
Qz-gt rock. 1765 Carbonate replacement or VHMS
Johnnies Cu-Au-Pb(Zn-Ag-Bi-Mo-Mn-Ca-HFSE-REE)
Mt-cpx-am±qz rock (after marble).
Qz-bt-gtgneiss in structural footwall to lode rock.
1795-1770
IOCG
Geoscience Australia
Characteristics of Utnalanama-type deposits
Mineralisation hosted by marble lenses within the Lower Strangways Metamorphic Complex (Ongeva package)
Age of host: 1810-1800 Ma
Psammo-pelitic sequence; volcaniclastic component
Size and grade of known deposits: to ~5 Mt at 2-4% Zn+Cu+Pb with Ag and Au credits
Dominant alteration: asymmetric quartz-cordierite rock;Lesser (minor) amphibole-rich assemblages;
Minor magnetiteGeoscience Australia
Utnalanama-type deposits – Edwards Creek
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Edwards Creek – Host sequenceMostly banded, felsic gneiss (includes massive felsic gneiss)Lesser mafic gneiss (sills) and micaceous schistForsterite marble and calc-silicate host mineralisation
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Local “clastic” textures
Local “quartz-eye” textures
Edwards Creek – Mineralisation and siliceous cap
Geoscience Australia
Surface assays (n = 11):to 3.3% Zn, 0.7% Pb, 0.8% Cu
(anomalous Bi & Cd)
Mineralised marble
Ore mineralogy:Sp > py ~ gn ~ cp > gh ~ mt
Surface assays (n = 12):to 1.3% Zn, 0.6% Pb, 0.6% Cu
(anomalous Ag, Bi, Cd, Mn & Bi)
Siliceous capTertiary weathering of marble
Hornblende-gahnite rock150 m along strike; up to 5 m wideTo 11.7% Zn (anomalous Bi, Cu,
Pb, Sn, Th and REEs)
Edwards Creek – Alteration assemblagesDominant meta-assemblage: cordierite-quartz rock (gneiss)
with local orthopyroxeneporphyroblasts
Minor meta-assemblage: gedrite-hercynite rock andmassive anthophyllite rock
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Edwards Creek – alteration geochemistry
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Talc
Quartz-cordierite rock & gedrite-hercynite rock:
Enriched in Fe(II), Mg, and, locally, Pb
Depleted in Na, Ca, Sr, Cu and, locally, K and Rbδ18O = 1.8-4.4‰
Quartz-cordierite rockGedrite-hercynite rockMassive tremolite rockHornblende-gahnite rock
Massive tremolite rock:Enriched in Mg and Ca
Depleted in Na, K and Rb
Pre-metamorphic alteration assemblagesQuartz-cordierite rock & gedrite-hercynite rock: Quartz-chlorite-muscovite & massive chlorite, respectivelyMassive tremolite rock: Talc-chlorite-carbonate
Utnalanama-type deposits – generalised model
500-1500+ m
Psammo-pelitic gneiss; quartzofeldspathic gneiss
Mafic gneiss
Quartz-cordierite rock (+Mg, Fe; -Na, Ca, K)
Cordierite rock;gedrite-spinel rock
Mineralised marble (Zn-Cu-Pb(Ag-Au-Cd-Bi)Tremolite rock
50-2
50 m
Inferred origin: volcanic-hosted massive sulphideGeoscience Australia
Characteristics of Oonagalabi-type deposits
Mineralisation hosted by marble lenses within the Bungitina Metamorphics (Ledan package)
Age of host: <1765 Ma
Psammo-pelitic sequence; volcaniclastic component
Size and grade of known deposits: to “25 Mt at 1%Zn and 0.5% Cu” with Au and Ag credits
Dominant alteration: massive anthophyllite rock;Quartz-garnet rock (in psammo-pelitic rocks);
Minor magnetite and quartz-cordierite
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Geoscience AustraliaGeoscience Australia
Oonagalabi-type deposits – Oonagalabi
Oonagalabi – Host sequenceUnit A: Banded, biotite-quartzo-feldspathic gneiss with minor1-3 mm garnet porphyroblasts. Host to mineralised carbonate lens.
Geoscience Australia
Unit B: Biotite-rich quartzo-feldspathic gneiss with distintive5-30 mm K-feldspar porphyro-blasts. Structurally underlies unit A.
Geoscience Australia
Oonagalabi – Mineralisation
Surface assays (n = 3):to 0.9% Zn, 0.3% Pb, 0.6% Cu
(anomalous Cd)
Mineralised marble
Ore mineralogy:Sp > po ~ cp > gn > gh ~ py
Surface and core assays (n = 7):to 2.9% Zn, 0.2% Pb, 2.7% Cu (anomalous Bi, Mo, Cd & Sn)
Massive anthophyllite rock
ParagenesisMarble → calc-silicate → massive
anthophyllite
Oonagalabi – Alteration assemblagesDominant meta-assemblage:
garnet-quartz rockRestricted in distribution: <20 m
from mineralised rock
Geoscience Australia
Minor meta-assemblages: Orthoamphibole-
orthopyroxene-magnetite-spinel rock, cordierite-quartz
rock andgahnite-quartz rock
Oonagalabi – Alteration geochemistry
Quartz-garnet rock:Enriched in Si, Fe(II), Mg, and,
locally, PbDepleted in Na, K, Ca, Sr, K and
Rb
Massive anthophyllite rock:Enriched in Mg, Fe and FDepleted in Na, K and Rb
Quartz-garnet rock: Quartz-rich quartz-chlorite altered unit A
Massive anthophyllite rock: Talc-quartz altered marble
Pre-metamorphic alteration assemblages
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Oonagalabi – Structure
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Tight, NE-plunging F3 folds on relatively flat form surface
Oonagalabi-type deposits – generalised model
Biotite-rich pelitic gneiss (unit B)
Mineralised marble
Quartzo-feldspathic gneiss (unit A)
Mineralisedanthophyllite rock
Calc-silicate
Garnet-quartz rock
100 m
Mafic gneiss
Inferred origin: carbonate-replacementGeoscience Australia
Zn-Pb-Cu prospects – Warumpi ProvinceNT
Iwupataka Metamorphic Complex
Host: Iwupataka Metamorphic ComplexAmphibolite-facies quartz-muscovite schist, calc-silicates
and amphibolites
Age: 1620-1610 MaExtensional/transtensional basins formed after accretion
of Warumpi Province onto North Australian CratonGeoscience Australia
N
020 m
DDH 1-3
DDH 4Pegmatite
Calc-silicate breccia
Amphibolite
leuco-gneiss
meta-pelite/psammite
1971-72 Five DDHs drilled by NTGS to test the mineralisation at depth.
Glen Helen Metamorphics
Stokes Yard Prospect
Stokes Yard
Mineralisation in N-S mylonite and breccia zone.
Surface Pb-Zn mineralisation occurs in calc-silicate.
1972 drilling program intersected narrow Cu mineralisation in altered amphibolite in breccia zone.
Surface Pb-Zn mineralisation not intersected.
Local geology, mineral association and alteration suggest the prospect is a deformed skarn occurrence.
Geoscience Australia
Lead isotopes
15.36
15.37
15.38
15.39
15.40
15.41
15.42
15.75 15.80 15.85 15.90 15.95 16.00206Pb/204Pb
207 Pb
/204 Pb
Utnalanama
Johnnie’s
Oonagalabi
Warumpi
Strangways evolutioncurve
Geoscience AustraliaMinerals Exploration Seminar 2003
ConclusionsThree styles and ages of Zn-Cu-Pb deposits in eastern
Aileron and Warumpi Provinces:Utnalanama-type: VHMS deposits hosted by 1810-1800 Ma
Ongeva packageOonagalabi-type: Carbonate replacement deposits hosted by
~1765 Ma Ledan packageStokes type: Skarn deposits hosted by 1620-1610 Ma Iwupataka
Metamorphics
All deposits closely associated with carbonate lenses
In Utnalanama- and Oonagalabi-type deposits, host has a volcaniclastic component
Geoscience Australia
Lead isotope data indicate the source of lead becomes progressively more primitive with younger age.