Geological Survey of South Australia -Industry presentation delivered at the 4th annual Resources Investment Symposium held in Broken Hill NSW Australia, 26-28 May 2014.

1. From paddling in the bathtub to
swimming the deep ocean:
the reality of this exploration metaphor in
the Curnamona Province and adjacent
regions
Steve Hill
Director
Geological Survey of South Australia
OPEN THE DOOR TO SOUTH
AUSTRALIA

2. Murphy’s “Haystacks” (Photo: S.Hill)
Pre-competitive Geoscience Data…
finding mineral system “Haystacks”

3. Moon Plain, Stuart Shelf, SA (Photo S.Hill)
Deep Cover Exploration Impediment…

4. Love thy Enemy
• Lots of cruel things said about the cover….
• “Impediment”
• “punch through” it!
• The rocks “suffered” weathering
• Ignore it
• “Stuff”
• “Overburden”
• “Crud”
• “Dirt”
• “*^#>” !!!
4
Why are people so unkind?
Fear and loathing. Where does it come from?
We don’t know it properly?
We don’t trust it

5. Be a Cover Lover!
5

6. This presentation
1. Geological Processes in the Cover (What are some of the
special things that can happen?)
2. Implications of these processes (How the cover can be our
BFF)
3. Characterising the cover (What do we really know about our
new found love?)
4. How to get to know the cover better into the future (our
enduring love)
5. Cover savvy geoscientists of the future (Who will be part of
this love affair?) 6

7. Geological Processes in the Cover: What are some
of the special things that can happen?
• Weathering / erosion / sediment and element accumulation
• Element mobility – source, transport, accumulation,
preservation
• Supergene enrichments
• Biogeochemical processes
• Placer concentration and recycling
• Geochemical footprint enlargement
• -------------------------------------------
• Dilution
• Barren cover (‘blind” deposits)
• Erosion / poor preservation
7
Weathering
ErosionSedimentation
Preservation
Leaching
Poor Preservation
Physical Dispersion
Burial
Re-accumulation
(“False anomaly”)
Dynamic
Equilibrium

8. Cover Processes and MaterialsWeathering
ErosionSedimentation
Preservation
Leaching
Denudation
Physical Dispersion
Burial
Re-accumulation
(“False anomaly”)
Dynamic
Equilibrium
Weathering
Erosion
Sedimentation
In situ
Deep
Weathering
“Residuum”
Variable profile
Materials exposed
Sediments /
Transported
material
PROCESS
MATERIAL

9. Gossans
Ferricrete
Weathered
Fe-skarn
Kaolinised Granite
Joints / Faults
Basal Gravels
Reduced/Oxidised clays & sands
Regolith Carbonates
Barren aeolian sands
Supergene Cu zone
HILLSIDE REGOLITH PROFILE

10. Tunkillia biogeochemical
model
(Lowrey & Hill, in prep.)
Central Gawler Craton
Deep cover Plant biogeochemistry

11. UoA Honours students
Black oak sampling April 2009
Minotaur Exploration
Drilling April 2010
Tunkillia, Gawler Craton

12. Implications of these processes:
How the cover can be our BFF
• Haloes / footprints
• 3D dispersion
• Secondary accumulations
• Other resources
• e.g groundwater, soils …..
12

13. After R E Smith & B Singh, 2007

14. Implications of these processes: How the
cover can be our BFF
14
• Eastern Gawler
Craton –
Curnamona
Province links
• ~1590 Ma
mineralising event
But dominated by different
exploration strategies
Eastern Gawler: IOCG in
basement
Curnamona: sedimentary U

15. IOCG – Porphyry – Epithermal Continuum (Claire Wade, GSSA)
Into the overlying cover???

16. Curnamona Province dispersion haloes shown on
radiometrics image
16
• Mt Painter
• Broken Hill
50 km

17. Scale of the distal footprint of the
Broken Hill mineral system
• Lateral dispersion for >100 km
– High grade garnets in beach sands
at Menindee Lakes (>100 km to SE)
– Staurolite and other high grade
metamorphic minerals in
sediments overlying low-grade
metamorphic rocks in the Fowlers
Gap and Bancannia Basin (>100 km
to N)
–Lateral dispersion onto Mundi Mundi
Plains (30-50 km to W and NW)

18. Catchment headwaters within
Barrier Ranges
Mundi Mundi Plains
Umberumberka
Reservoir
Umberumberka Creek - Broken
Hill (Charlotte Mitchell, DET CRC)

19. Catchment headwaters within
Barrier Ranges
Mundi Mundi Plains
Umberumberka
Reservoir
Umberumberka Creek - Broken
Hill (Charlotte Mitchell, DET CRC)

20. Mundi Mundi Plain
• Lateral dispersion
and reaccumulation
• Important balance
between processes of
erosion, sedimentation
and weathering / soil
formation

21. Characterising the cover: What do we
really know about our new found love?
• Characterising the cover – a big opportunity!
• Greater amount of surficial data but really decreases
with depth
• Key attributes:
• Detailed lithological logging
• Whole-rock geochemistry (chemical context?)
• Mineralogy (XRD and spectral)
• Physical properties
21

22. Deep Cover Reference Sections
• Geological type sections and their associated data have received
diminished attention, particularly since the GSSA work in basin
areas in 1970s and 1980s
• These are important reference sections, particularly as exploration
moves into surrounding covered areas.
• Modern data for these sections can include:
• GPS coordinates
• Lithological logging
• Biostratigraphy
• HyLogger mineralogy
• Lithogeochemistry
• Detrital zircon dating
• et al……
22

23. Trinity Well type section, Marree
1:250k mapsheet
23

24. Trinity Well Reference Section
24

25. Deep cover atlas of SA (DET CRC)
…
25

26. Exploration Sampling Media within
the Cover (DET CRC)
• An ideal sampling medium needs to be:
• Abundant
• Generic (e.g. not just restricted to a particular stratigraphic
unit)
• Readily identifiable (esp. down-hole)
• Hosts target geochemical suite for mineral system
• Can be linked to dispersion vectors (can be used as
geochemical vector to mineralisation)
• Able to be effectively and efficiently sampled

27. Some examples of efficient and
effective approaches to exploring
in covered terrains?
1. Understanding the geological history of gold
dispersion at Tibooburra
2. Exploring through sediment for Broken Hill
type mineralisation at the Pinnacles
3. Putting it all together for sedimentary
uranium exploration through the cover at
Four Mile

28. CASE STUDY 1: Tibooburra Au
provenance...
Tors of Tibooburra Granodiorite (photo S.Hill)

29. Tibooburra-Milparinka Au-fields
(Thomson Orogen NSW)
From Hill et al 2009

30. Tibooburra-Milparinka Au-fields
Depth of Basin Cover
(Mesozoic and younger)

31. Radial ‘shedding’ model
Tibooburra Inlier
No! This applies to contemporary drainage but not the Mesozoic system
Mesozoic
hinterland-basin
geochemical
reconstruction
needed!

32. Au hosted in basal Mesozoic
sediments

33. (Hill, 2005)
Late Jurassic
(basal Mesozoic)
palaeolandscape

34. Au-bearing Basal Mesozoic palaeocurrent vectors
Tibooburra Inlier (Hill et al 2009)

35. Tibooburra: Mesozoic palaeoflow model
in relation to historic Au diggings (Hill et al 2009)
Emergent
.The Granites
.Easter Monday
.Tunnel Hill
.Six Mile

36. Deeply buried Au Provenance? (Hill et al 2009)
Mt Browne Inlier
Au bearing Basal
Mesozoic
flow vectors
Buried Au
source
target areas
Tibooburra Inlier

37. Deeply Buried Au Provenance?
Tibooburra Inlier
NSW GS, 1VD magnetics
Mt Browne Inlier

38. CASE STUDY 2: The Pinnacles …

39. Looking South down Pine Creek from Middle Pinnacle
Pinnacles
Mine
Pine Creek
South
Pinnacle

40. S.Hill Pinnacles pilot study: river red gum leaves (~250
m sample spacing)
0
50
100
150
200
250
300
350
0 2 4 6 8 10 12
Channel Distance (km)
Pb(ppm)
Pinnacles
mineralisation?
Wasn’t sure if this staggering result was current mine or new mineralisation?
What does an academic do when they don’t know something? ……

41. Get a PhD student to work on it –
Karen Hulme

42. Pine Creek…
Sample spacing
– every collectable RRG
• 215 River Red gums sampled
– Media
• Leaves
• Chest height
• Sample size~300g
Middle Pinnacle
Pinnacles Mine

43. Lead…
•Pb up to 205 times
background levels
•Geochemical footprint
~ 2.5 km
0 – 36 ppm
37 – 99 ppm
100 – 190 ppm
191 – 411 ppm
Hyperspectral Image, courtesy NSW DPI
N
2 km

44. Silver…
• Ag up to 136 times
background value
• Geochemical
footprint 2.2 km
0.005 – 0.100 ppm
0.101 – 0.340 ppm
0.341 – 0.710 ppm
0.711 – 1.360 ppm Hyperspectral Image, courtesy NSW DPI
N
2 km

45. Zinc…
• Zn up to 7 times background
values
• Erratic pattern (repeated)
– mobility
– peaks related to floodouts
17 - 47 ppm
48 - 80 ppm
81 - 141 ppm
141 – 338 ppm Hyperspectral Image, courtesy NSW DPI
N
2 km

46. It was time to dig…
Sarah ‘Gibbo’ Gibbons (earnest,
hard-working CRC LEME Honours
student)
Photos: Karen Hulme

47. Pinnacles - lodes extensions
Photographs: Steve Hill Mineralisation continues near surface but below main road!

48. Kangaroo Prospectors
– Western Grey Kangaroos
• Selective browser
• Well defined home range
• Scat chemistry reflects Broken Hill mineralisation (esp.
Pb, Zn, Cd)
• Implications for exploration and geo-health

49. Kangaroo Prospectors

50. Broken Hill Roo Poo Pb
0
100
200
300
400
500
600
700
-60 -40 -20 0 20 40 60
Dist (km)
Pb(ppm)
Broken Hill
West East
Pinnacles

51. Zn and Cd in roo poo
Broken Hill Roo Poo Zn
0
200
400
600
800
1000
1200
-60 -40 -20 0 20 40 60
Dist (km)
Zn(ppm)
Broken Hill Roo Poo Cd
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
-60 -40 -20 0 20 40 60
Dist (km)
Cd(ppm)
Broken
HillBroken
Hill
West East West East

52. Skippy knows where to find the ore?
• The kangaroos very effectively intake chemical
signatures from buried rocks when they eat
plants.
• They do this over a range of 10s of kilometres
• They redeposit this chemical signature in their
poo
• Mineral explorer samples the poo, prepares it
and gets it analysed to look for its chemical
signatures

53. CASE STUDY 3: Four Mile U
(Steve Hore & Steve Hill, GSSA)

54. Four Mile East
Dead Tree Section
Four Mile Creek
Four Mile West
Beverley

55. F
Four Mile East
Dead Tree Section – Eyre Formation sample locations
20m

56. Four Mile West:
Deadtree Section
Namba Fm
Pedogenic Silcrete
Eyre Fm
Bulldog Shale &
Cadna-owie Fm
Saprolite

57. (Hill, 2005)
Late Jurassic

58. Mesozoic Glaciations
• Widespread dispersal of U-rich detritus in
Early Cretaceous glaciers
Recorder Hill

59. Mesozoic Glaciations
• Important context for Four Mile West U
deposit
Palaeoredox interfaces in Mesozoic diamictite at Deadtree section (Hore & Hill, 2009)

60. (Hill, 2005)
Early Cretaceous

61. Mt Babbage Inlier
(U-rich granites)
Oxidised
Bulldog Shale

62. Mt Babbage Inlier
U-rich bedrock
Mesozoic sediments

63. (Hill, 2005)
Palaeogene

64. Eyre Formation (Palaeogene)
• Flinders Ranges existed at this time
– Palaeoflow along range-front (rather than across it!)
– Highly weathered provenance
• Warm-wet palaeoclimate
– Abundant vegetation cover
– Weathering rate > erosion rate
– Organic detritus

65. Eyre Formation (palaeo-redox fronts) – Important U host
(Four Mile, Honeymoon, Goulds Dam, Oban)

66. Namba Fm (Miocene) – hosts Beverley

67. Namba Formation
Top of Namba Fm
Top of Saprolite
(Wooltana Volcanics)
Willawortinna Fm outwash gravels

68. (Hill, 2005)
Neogene

69. Proterozoic basement
Willawortina Ftm
Eyre Formation
geologists

70. ~ 5 km
Four Mile East
Four Mile West
?
?

71. ~ 5 km

72. ~ 5 km
Preserved Tertiary
Exposed Mesozoic

73. Four Mile Stream Sediments (GSSA Radiometrics)
NB. High U content of detritus from
ranges overlying basin prospective
for buried sedimentary U

74. Four Mile Prospect soil U
Neimanis et al 2007

75. Four Mile Stream Sediments (McMahon
& Hill, 2007)
0
20
40
60
80
100
120
0 1000 2000 3000 4000 5000 6000 7000
Sample distance downstream (m)
U(ppm)
Fine sediment fraction
(-80 mesh)
Mineralisation
surface projection

76. Four Mile Regolith Carbonates
(Gallasch & Hill, 2007)
Media Comparison of U vs Th (Four Mile Catchment)
0
50
100
150
200
250
300
350
0 50 100 150 200 250 300
U (ppm)
Th
(ppm)
Carbonate
Bedrock
Th > U
U > Th

77. Radium Ridge
Image: Steve Hill
Eucalyptus gillii
0.12 – 6.59 ppm U
4.79 – 33.42 ppm Cu
0.01 – 0.02 ppm Th
Eucalyptus intertexta
0.06 – 6.49 ppm U
2.74 – 12.21 ppm Cu
0.01 – 0.04 ppm Th

78. FOUR MILE BIOGEOCHEMISTRY: TARGET SPECIES
Allows subsurface access to culturally and environmentally sensitive sites
River Red Gum
Inland tea-tree

79. Neimanis, Hill & Hore, 2007
Inland Tea-tree shows similar results to stream sediments!
(shallow alluvial aquifer)

80. Neimanis, Hill & Hore, 2007
River red gum shows deeper mineralisation expression along structures
(deeper fractured aquifer)

81. U2 / Th
river red gum
leaves

82. Ant biogeochemistry (Iridomyrmex
spp.)
Meat Ant Distribution
www.ento.csiro.au/science/ants
Courtesy Deanne Gallasch

83. Ant Nest Soils
Projected Mineralisation
Legend
Uranium (nest material)
Value (ppm)
3.5 - 30.0
30.1 - 57.0
57.1 - 118.0
´
0 1,000 2,000500
Metres
GRID NORTH
GDA 1994 (Zone 54)
351500.000000
352500.000000
353500.000000
353500.000000
354500.000000
354500.000000
355500.000000
355500.000000
356500.000000
356500.000000
357500.000000
357500.000000
358500.000000
359500.000000
6660000.000000
6661000.000000
6662000.000000
6663000.000000
6664500
.000000
6665500
.000000
6666500
.000000
(Jennings, Hill, Wright & Kirby, 2007)

84. Ant Biogeochemistry
(Jennings, Hill, Wright & Kirby, 2007)
Projected Mineralisation
Legend
Uranium (ants)
Value (ppm)
0.027 - 1.417
1.418 - 4.302
4.303 - 13.035
´
0 1,000 2,000500
Metres
GRID NORTH
GDA 1994 (Zone 54)
351500.000000
352500.000000
353500.000000
353500.000000
354500.000000
354500.000000
355500.000000
355500.000000
356500.000000
356500.000000
357500.000000
357500.000000
358500.000000
359500.000000
6660000.000000
6661000.000000
6662000.000000
6663000.000000
6664500
.000000
6665500
.000000
6666500
.000000

85. Roo Poo Biogeochemistry (McMahon & Hill, 2007)

86. Four Mile Uranium: summary
• Long history of U dispersion (at least Mesozoic) across
landscape
• Abundant surface anomalism but links to buried
mineralisation challenging
• Vegetation and to some extent carbonates have best links
with buried mineralisation (via groundwater)
86

87. So what have we learnt
• The cover can be our friend and host some
advantages to exploration (e.g. enlarged
“footprints”)
• The cover needs to be dealt with the same
geological rigor as hard rocks (e.g.
palaeodrainage reconstruction)
• A range of sampling media are available within
the cover and be efficiently and effectively
used in different ways (e.g. the provide an
exploration tool kit)

88. Plant biogeochemistry providing surficial
expression of sub-surface chemistry
Biogeochemistry

89. →
Cost and Time efficient subsurface chemical information
(help focus and rank drilling targets)

90. Advantages of plant biogeochemical exploration
• Provided sampling procedure is orientated and systematic:
• Time efficient
• Minimal environmental impact
• Minimal cultural impact
• Flexible site access needs
• Cost equivalent to soil geochemistry

91. Cover savvy geoscientists of the future:
Who will be part of this love affair?
• Part of integrated geoscience workflow
• Given the expanse of cover …. Where are our
cover savvy geoscientists coming from?
• Are training institutions engaged and providing
the relevant foundations?
91

92. Photo: Steve Hill92
Western Gawler Craton – Eucla Basin….

93. South Australian Mineral Exploration Licences
January 2004 September 2013

94. Pre-competitive Geoscience workflow for
western Gawler Craton – Eucla Basin
94
Regional Geophysics
Regional Geochemistry
Regional Geological Mapping
Lithospheric Architecture
Stratigraphic Drilling
250k Geological Mapping
Targeted Geophysics and Geochemistry
4D Geodynamic & Metallogenic evolution
Regional Mineral System Drilling
Geophysical & Geochemical Case studies
‘Distal Footprint’ Characterisation
Mineral Occurrence Studies
Collaborative / Targeted drilling
Tenement
Exploration
PACE FRONTIERS in 2014
• Eucla Seismic Line
• Regional MT survey
• New airborne geophysics
• Regional Biogeochemistry

95. Western Gawler / Eucla Basin Continental
Seismic Transect (TMI backdrop)
95
Coompana
Anomaly
Fowler
Domain
Gawler
Ranges

97. Eucla Basin – Gawler Craton MT

98. Western Gawler / Eucla Basin Regional
Geophysics
• Magnetics
• Radiometrics
Older airborne surveys
1600-3000 line spacing
(did not always collect
radiometrics)

99. Western Gawler / Eucla Basin Geochemistry / Biogeochemistry
• Regional
Geochemistry
– 2013-14
• Hydrogeochemistry
• Soil
• Calcrete
• Biogeochemistry
~450 plant samples
~170 sample sites

100. Western Gawler / Eucla Basin
Future Program
• Gravity survey
• Soil Geochemistry
• Integration, Interpretation and value-add
• REGIONAL DRILLING
• Coompana Competition?
• Phase I: service provider data acquisition
• Phase II: Geological Interpretations
• Phase III: Regional Drilling and ‘real time’ reinterpretations

101. Thank-you….
Yours Lovingly
Steve
(Your Cover Lover Brother)
101

102. Disclaimer
The information contained in this presentation has been compiled by the
Department for Manufacturing, Innovation, Trade, Resources and Energy
(DMITRE) and originates from a variety of sources. Although all reasonable care
has been taken in the preparation and compilation of the information, it has been
provided in good faith for general information only and does not purport to
be professional advice. No warranty, express or implied, is given as to the
completeness, correctness, accuracy, reliability or currency of the materials.
DMITRE and the Crown in the right of the State of South Australia does not accept
responsibility for and will not be held liable to any recipient of the information for
any loss or damage however caused (including negligence) which may be directly
or indirectly suffered as a consequence of use of these materials. DMITRE
reserves the right to update, amend or supplement the information from time to
time at its discretion.