ausim uranium conference 2012 presentation
DESCRIPTION
Presentation given at the 2012 Adelaide, Ausim Uranim Conference. Authors Mike Hussey and Brigette Martini.TRANSCRIPT
Mapping Calcrete Mineralogy using HyMap Imagery in Western Australia and Namibia
HyVista Corporation
11/10 Gladstone Rd., Castle Hill, NSW, AUSTRALIA
www.hyvista.com
M. Hussey and B. A. Martini
Uranium Mapping Projects
Four types of Uranium deposits successfully mapped thus far:
Unconformity associated – eg. Ranger (Alligator River) & Pine Creek,
NT; Angelo River (Kurradong), WA
Surficial deposits, calcrete-hosted – eg. Mason Lake (Yeelirrie), WA; Langer Heinrich and Trekkopje, Namibia
Carbonatite associated – eg. Mud Tank, NT; Lofdal & Rossing, Namibia
Metasomatic – Valhalla, Bikini & Skal, Mt. Isa, QLD
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Hyperspectral Imaging – Spectrometry From The Air
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Spectral Regions Relevant to Geology
Visible and near infrared 400 - 1000 nm (VNIR) Iron oxides and iron bearing minerals (Hematite, Goethite, Jarosite) Rare Earth Minerals Vegetation
Shortwave Infrared 1000 - 2500 nm (SWIR) OH-bearing minerals
Clay Minerals Micas Amphiboles Serpentine, Talc, Chlorites, Epidote
Phosphates Sulfates Carbonates Hydrocarbons
Cellulose (Vegetation) Oils and Waxes (Petroleum and Vegetation) Plastics Methane
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Spectral Signatures: Uranium Alteration Assemblages
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HyMap Instrument >1,000,000km2 worldwide
Spectral Configuration – 128 channels
Module Spectral range Bandwidth
across module
Average spectral sampling interval
VIS 0.45 – 0.89 um 15 – 16 nm 15 nm
NIR 0.89 – 1.35 um 15 – 16 nm 15 nm
SWIR1 1.40 – 1.80 um 15 – 16 nm 13 nm
SWIR2 1.95 – 2.48 um 18 – 20 nm 17 nm
SNR average of 1000:1
~3-50m pixels (hardened for high-altitude, extreme cold and heat)
60° FOV (strip width ~2.5km at 5 m pixel, ~1.4km at 3.5 m)
1000km2/day (optimal conditions @ 5m)
Seamless mineral mapping and geophysical/geochemical integration (~1-6 weeks)
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Western Australia Uranium Deposits
Calcrete-hosted Uranium within the Murchison of the Yilgarn Craton
www.dmp.wa.gov.au
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Yeelirrie, Yilgarn Craton, Western Australia
World’s largest surficial, calcrete-hosted deposit
Located on the northern margin of the Yilgarn Craton in the Northeastern
Goldfields; found in 1972 by WMC Resources (taken over by BHP in ‘05)
Mineralised calcretes formed above Archean granites and greenstones; ore zones are within the valley paleodrainage systems; all carnotite
Calcrete outcrop is poor with 1-2 m of sand loam and clay overburden
The Yeelirrie Pit, BHP Billiton
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Yeelirrie HyMap Survey – Two flight lines at 4m resolution
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Yeelirrie Alteration Mineral Map
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Yeelirrie Alteration Mineral Map – Mine Close-up
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Yeelirrie Alteration Mineral Map: Deposit Alteration Model
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Lake Mason, Yilgarn Craton, Western Australia
Surficial, calcrete-hosted deposit
Located approximately 80km southwest of the Yeelirrie deposit in the
eastern Murchinson region of WA; found in the 1970’s by BP Minerals via shallow carnotite shows
Mineralised zones associated with the valley calcretes of the Lake Mason drainage system
Defined Mineral Resource of 9.1Mt U3O8 at 185 ppm U3O8 (100ppm cut-off)*
The sandstones of the central Yilgarn *figures downloaded from Energy Metals Limited, 5June2012
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A standard decorrelation stretch brings out gross lithology and mineral assemblages -Comparable to nearby Yeelirrie, the calcretes have formed over a similar granitoid basement
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Leveraging the 100 + bands of HyMap, we map specific mineralogy -Three types of clay (Halloysite, Kaolinite and Nontrite) are readily discriminated and mapped
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Mineral mapping indicates paleochannels contain Gypsum, Mg-rich Smectite…
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…Dolomite and Calcite. The magnesium-rich smectite (mapped in red) may represent weathered dolomites at depth
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HyMap-derived alteration maps provide a new way of mapping sub-surface and/or weathered calcrete bodies
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Nambian Uranium Deposits
Current mines produce
approximately 10% of world
Uranium demand
- Langer Heinrich is the second largest mine in Namibia behind Rossing
Namibian Geologic Survey
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Langer Heinrich, Damara Uranium Province, Namibia
Surficial, calcrete-hosted deposit
Located approximately 80km east of Walvis Bay in central Namibia; found
in 1973 by a large-area government sponsored airborne radiometric survey
Consists of seven mineralised zones within a 15km long paleodrainage system
Mineral resource of 74,415t U3O8 at a grade of 0.06% U3O8 (250ppm cut-off)*
Primary ore mineral is carnotite
From Paladin Energy Ltd. *figures downloaded from Paladin, 5June2012
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Langer Heinrich, Damara Uranium Province, Namibia
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Langer Heinrich – Broad Lithologic Differentiation
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Langer Heinrich – HyMap derived mineral map
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Known mineralised calcrete bodies
Calcite predominately defines the calcretes in this area
Calcrete Exploration Targets
Residual muscovite rich sand partially covers some of the calcrete
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Conclusions
We have successfully mapped surficial calcrete-hosted uranium deposits in Western Australia and Namibia
Despite poor exposure, calcrete bodies are mappable using airborne imaging spectroscopy (eg. HyMap) via detailed detection of not only host carbonates, but also their weathering products
The large area coverage (coupled with high spatial resolution) afforded by airborne scanners provides new ways to:
Expand currently known deposits
Step out the boundaries of larger districts
Undertake pure, large-area, green-field
exploration
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