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Martin Moloney Principal Geologist – New Commodities
Grassroots nickel sulphide exploration in the western Gawler Craton, South Australia South Australian Exploration and Mining Conference 2nd December 2016
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Target overview: Greenfields magmatic Ni-Cu-Co-PGE sulphides Pipeline Stage: Prospect-scale Target Identification Ownership: Iluka Resources 100%
Summary:
• Tenement package around Jacinth HM deposit ~ 22,500 sq. km • Province-scale NiS grassroots campaign undertaken by Iluka • Results validate generative concept • Substantial remaining prospectivity
Overview
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Regional Geology
• Archean margin • Inverted rift structure • Broad gravity high - 200km x 60km
(onshore) • Voluminous Paleoproterozoic mafic
intrusive rocks • Amphibolite – Granulite facies met. • Steep dips • Outcrop < 1% - cover 0-100m • Residual profile
PIRSA Mesa Journal 39 2005
Iluka 100% Tenure (Nov. 2016)
AOI
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Multidisciplinary Exploration Campaign
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Summary of Exploration Methods
Regional-Scale Prospect-Scale
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Magnetics
150,000 line km, 100m spacing, low-level acquisition
Mag RTP – linear stretch
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Data Acquisition - pXRF
Iluka’s library of AC drilling samples: • 000’s drillholes • ~30% intersected basement • initial geochemical evaluation via pXRF
analysis
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Magnetics & pXRF
Cluster of anomalous chalcophile results from
pXRF
Woodford
Mag RTP – linear stretch
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Ground Gravity
5,773 stations acquired at nominal 1,000m / 400m spacing
400m infill
Yalata license not yet completed
Bouguer Residual
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Airborne & Ground EM
VTEM: 5169.8 line km 35% effective to moderate depths 250 anomalies detected 8 high priority / 52 moderate priority
Ground EM coverage
Conductive cover remains challenging for airborne EM Stratigraphic conductors in Proterozoic absent
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VTEM reveals probable impact crater
VTEM Gravity Res.
Mag RTP Topography
Conductive sediment filled depression (2km wide, ~225m thick) Resistive crater rim (5km diameter)
Wolf Creek
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Geological Synthesis
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Target / AC drilling summary Magnetics imagery with gravity anomalies
RTP Magnetics Imagery with Gravity Anomalies
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Emphasis on data synthesis esp. in the field
Critical to vector toward the base of each intrusion to prioritise infill
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Woodford Drill Section
Sulphidic
metasediment
Gabbros
Hornfelsed
metagranite
Gravity 1VD Profile
188AC (eastern margin):
Mineral layering at ~50° to
long core angle = dip of
syncline limb
• AC defines
Syncline structure
• Ultramafic base
exposed on
eastern margin
V/H = 10
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MLEM
Limit of MLTEM effectiveness (approx. 500 m)
Upper mafic zone
Lower ultramafic zone
Woodford Intrusion
Woodford Simplified Interp Section
Residual Profile
Cover
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Mapping Intrusive Structure – Targeting EM
• Pyroxenites (182AC / 188AC)
expressed as mag low on
eastern margin of syncline
• Integrating magnetics with AC
results defines search space
for basal nickel sulphides
Layered
Gabbro
RTP Residual Magnetics Imagery
Ground EM Survey Plan
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AC Geochemical Ranking 1 Compatible immobile trace element variations in AC samples by Prospect
High levels exposed
Lower levels exposed
9 8 14 2 2 6 2 3 5 6 13 3 5 1 7 1 1 5 3 16
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9 8 14 2 2 6 2 3 5 6 13 3 5 1 7 1 1 5 3 16
AC Geochemical Ranking 2 Chalcophile trace element variations in AC samples by Prospect
188AC 85.5m Pyrite & millerite FOV = 1mm
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AC Chalcophile Elements Map
~30% of intrusions tested with AC have evidence of magmatic sulphide Substantial scope for further exploration
“Tested” by systematic ground EM
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Ground EM Defines Drilling Targets
F1_6
Ground EM provides highly specific drill targets Follow-up assessed / prioritised in terms of size and strength (conductance)
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Drilling Targets from Ground EM
TARGET EAST NORTH RL DIP AZIMUTH EOH Area TARGET DEPTH
F1_6 305070 6603335 213 60 270 200-250 70m x 130m 125-200 F1_5 294070 6594500 162 75 140 300 75m x 400m 150-250 Y1_2 344000 6496675 111 65 320 350-375 400m x 200m 250-350 F1_7 STH 303550 6593825 160 80 315 200 250m x 350m 100-150 F1_7 NTH 303420 6594480 169 60 315 200 500m x 750m 100-150
• VTEM surveying / ground EM follow-up defined 5 legitimate bedrock conductors
• PACE Funding approved for co-funding of DD for F1_5, F1_6 & F1_7 targets
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1. Essential elements for Ni mineral system present at regional – camp scale
2. Gravity / magnetics essential in directing exploration toward mafic / ultramafic intrusions
3. AC drilling at 200m spacing provides vectors toward potential trap sites within intrusions and
helps rank intrusions
4. VTEM surveying effective to a depth of ~200m over ~35% of area flown
5. Systematic EM surveying can screen prospective intrusions prior to follow-up drilling
6. Several intrusions have magmatic Cu-Ni sulphides (petrographic & geochemical evidence)
7. Many untested intrusions remain in the region
Summary
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Substantial prospectivity remains within the Project area:
1. Untested mafic intrusion targets in Northern Zone (defined by detailed gravity)
2. Various Ground EM and VTEM targets
3. Southern half of belt / tenure not tested (around Yalata)
4. Ooldea Gravity High
Fowler Domain Prospectivity
Iluka is considering the best way to take the project forward
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Iluka Resources Limited www.iluka.com
For more information, contact: Martin Moloney, Principal Geologist – New Commodities [email protected] +61 8 9360 4677 / +61 (0) 477 369 934