The Frome airborne electromagnetic survey, South Australia

310 Pages·2012·21.48 MB·English

G E O S C I E N C E A U S T R A L I A
The Frome airborne electromagnetic
survey, South Australia:
Implications for energy, minerals and regional geology
Edited by I. C. Roach
With contributions from: R. C. Brodie, M. T. Costelloe, A. J. Cross,
Record
T. Dhu, A. J. Fabris, S. B. Hore, E. A. Jagodzinski, S. Jaireth, L. F. Katona,
J. L. Keeling, P. D. Magarey, A. B. Marsland-Smith, B. H. Michaelsen,
2012/40
I. C. Roach, C. E. Wade and T. Wilson
GeoCat #
73713
DMITRE
Report Book
2012/00003
APPLYING GEOSCIENCE TO AUSTRALIA’S MOST IMPORTANT CHALLENGES

The Frome airborne electromagnetic
survey, South Australia: implications for
energy, minerals and regional geology

GEOSCIENCE AUSTRALIA
RECORD 2012/40

GEOLOGICAL SURVEY OF SOUTH AUSTRALIA
REPORT BOOK 2012/00003

Edited by

I. C. Roach1

With contributions from:

R. C. Brodie1, M. T. Costelloe1, A. J. Cross2, T. Dhu3, A. J. Fabris3, S. B. Hore3, E. A. Jagodzinski3,
S. Jaireth2, L. F. Katona3, J. L. Keeling3, P. D. Magarey4, A. B. Marsland-Smith5, B. H. Michaelsen3,
I. C. Roach1, C. E. Wade3 and T. Wilson3.

1. Continental Geophysics, Minerals and Natural Hazards Division, Geoscience Australia, GPO Box 387, Canberra ACT 2601
Australia.
2. Resources, Advice and Promotions, Minerals and Natural Hazards Division, Geoscience Australia, GPO Box 387, Canberra
ACT 2601 Australia.
3. Geological Survey of South Australia, South Australia Department for Manufacturing, Innovation, Trade, Resources and
Energy, GPO Box 1264, Adelaide SA 5001, Australia.
4. South Australia Department for Water, Level 11, 25 Grenfell St, Adelaide, SA 5000, Australia
5. Heathgate Resources Pty Ltd, Level 4, 25 Grenfell St, Adelaide, SA 5000, Australia
Department of Resources, Energy and Tourism
Minister for Resources and Energy: The Hon. Martin Ferguson, AM MP
Secretary: Mr Drew Clarke

Geoscience Australia
Chief Executive Officer: Dr Chris Pigram

South Australia Department for Manufacturing, Innovation, Trade, Resources and Energy
Minister for Mineral Resources and Energy: The Hon. Tom Koutsantonis, MP

DMITRE, Resources and Energy Group
Deputy Chief Executive: Dr Paul Heithersay

© Commonwealth of Australia (Geoscience Australia) 2012

With the exception of the Commonwealth Coat of Arms and where otherwise noted, all material
in this publication is provided under a Creative Commons Attribution 3.0 Australia Licence
(http://www.creativecommons.org/licenses/by/3.0/au/)

Geoscience Australia has tried to make the information in this product as accurate as possible.
However, it does not guarantee that the information is totally accurate or complete. Therefore, you
should not solely rely on this information when making a commercial decision.

ISSN 1448-2117
ISBN 978-1-922103-26-0 print
ISBN 978-1-922103-25-3 web

GeoCat # 73713

Bibliographic reference: Roach, I. C. ed. 2012. The Frome airborne electromagnetic survey, South
Australia: implications for energy, minerals and regional geology. Geoscience Australia Record
2012/40 – DMITRE Report Book 2012/00003, 296 pp.
The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
and regional geology
Contents

Executive Summary ........................................................................................ 1

1 Introduction (I. C. Roach and M. T. Costelloe) .....................................................3
1.1 Survey rationale........................................................................................................................3
1.2 Survey location.........................................................................................................................3
1.3 Survey Geo-economic framework............................................................................................5
1.3.1 Uranium mineral deposits.................................................................................................5
1.3.2 Metal deposits...................................................................................................................8
1.3.3 Non-metal, industrial mineral and energy commodity deposits.......................................9
1.3.4 Groundwater systems........................................................................................................9
1.3.5 Geothermal energy............................................................................................................9
1.4 Area Assessment.....................................................................................................................10
1.4.1 Targets: geo-electrical forward modelling for system selection.....................................10
1.4.2 Terrain affecting aircraft operations (drape)...................................................................11
1.4.3 Aircraft access................................................................................................................13
1.4.4 Native title, no-fly zones and state government land access issues................................13
1.4.5 Climate...........................................................................................................................15
1.4.6 Communication strategy.................................................................................................16
1.5 Survey infill partners and cost.................................................................................................17
1.6 Final survey design.................................................................................................................18
1.7 References...............................................................................................................................21

2 Previous investigations (I. C. Roach, M. T. Costelloe and S. Jaireth)................ 23
2.1 Introduction.............................................................................................................................23
2.2 Geological mapping................................................................................................................23
2.2.1 Surface geology mapping...............................................................................................23
2.2.2 Solid geology mapping...................................................................................................23
2.3 Regolith-landform and soil mapping......................................................................................26
2.4 Specialist geological publications...........................................................................................31
2.4.1 Geology and geodynamics..............................................................................................31
2.4.2 Regolith geology and geomorphology............................................................................32
2.4.3 Geochronology...............................................................................................................33
2.4.4 Mineral resources and mineral systems..........................................................................33
2.5 Drilling....................................................................................................................................35
2.6 Mineral exploration lease status before and after the survey..................................................36
2.7 Geophysical mapping and remote sensing..............................................................................38
2.7.1 Airborne geophysics.......................................................................................................38
2.7.2 Seismic and magnetotellurics.........................................................................................41
2.7.3 Remote Sensing..............................................................................................................41
2.8 3D models...............................................................................................................................43
2.9 Groundwater...........................................................................................................................43
2.10 References.............................................................................................................................44

3 Geology, physiography, landscape evolution and mineral systems (I. C. Roach,
S. Jaireth, C. E. Wade, A. J. Cross, S. B. Hore and E. A. Jagodzinski) .............. 53
3.1 Introduction.............................................................................................................................53
3.2 Regional geology....................................................................................................................53
3.2.1 Paleo-Mesoproterozoic Curnamona Province................................................................53
3.2.2 Neoproterozoic...............................................................................................................58
3.2.3 Paleozoic.........................................................................................................................61
3.2.4 Mesozoic.........................................................................................................................61
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The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
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3.2.5 Cenozoic.........................................................................................................................65
3.2.6 Quaternary......................................................................................................................73
3.2.7 Granites and other felsic rocks.......................................................................................73
3.3 Physiography...........................................................................................................................79
3.4 Regolith geology.....................................................................................................................82
3.4.1 In situ regolith.................................................................................................................84
3.4.2 Transported regolith........................................................................................................86
3.4.3 Indurated regolith...........................................................................................................93
3.4.4 Vegetation.......................................................................................................................94
3.5 Landscape evolution...............................................................................................................97
3.5.1 Proterozoic-Paleozoic.....................................................................................................97
3.5.2 Mesozoic-Cenozoic......................................................................................................100
3.5.3 Evolution of the modern landscape..............................................................................102
3.6 Mineral systems....................................................................................................................105
3.6.1 Features of sandstone-hosted uranium systems in the Callabonna Sub-basin..............108
3.6.2 Geological setting.........................................................................................................108
3.6.3 Energy Drivers of the system.......................................................................................110
3.6.4 Source of uranium........................................................................................................112
3.6.5 Fluid pathways..............................................................................................................114
3.6.6 Chemical and/or physical traps/gradients.....................................................................115
3.6.7 Age of uranium systems...............................................................................................116
3.6.8 Preservation of uranium systems..................................................................................116
3.7 References.............................................................................................................................117

4 AEM Geophysics (M. T. Costelloe and I. C. Roach)...........................................125
4.1 Introduction...........................................................................................................................125
4.2 Released data........................................................................................................................125
4.3 The TEMPESTTM AEM system............................................................................................126
4.4 Background to the GA layered earth inversion.....................................................................128
4.5 The GA layered earth inversion............................................................................................129
4.5.1 Algorithm outline.........................................................................................................129
4.5.2 Sample-by-sample (SBS) inversion..............................................................................129
4.5.3 Conductivity model parameterization...........................................................................130
4.5.4 Line-by-line (LBL) inversion.......................................................................................131
4.5.5 Reference Model...........................................................................................................133
4.5.6 Data Misfit....................................................................................................................133
4.5.7 Depth of Investigation..................................................................................................133
4.6 Geo-electrical models...........................................................................................................134
4.7 GA-LEI products...................................................................................................................135
4.7.1 Sections.........................................................................................................................135
4.7.2 Georeferenced JPEGs...................................................................................................135
4.7.3 GOCADTM Triangulated Surfaces................................................................................137
4.7.4 Geoscience Australia layered earth inversion multiplots..............................................137
4.7.5 Grids.............................................................................................................................137
4.7.6 Gridding Parameters.....................................................................................................138
4.7.7 AEM Go-Map...............................................................................................................139
4.7.8 Depth Slices..................................................................................................................141
4.7.9 Elevation Slices............................................................................................................141
4.8 Discrete Conductors..............................................................................................................144
4.9 Borehole conductivity validation..........................................................................................145
4.10 Statistical Comparison........................................................................................................147
4.11 Quality assurance and quality control.................................................................................147
4.12 References...........................................................................................................................152
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The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
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5 Interpretations of AEM Data ..............................................................................155
5.1 Introduction (I. C. Roach and M. T. Costelloe)....................................................................155
5.2 Mapping regional geology (I. C. Roach and M. T. Costelloe)..............................................157
5.2.1 Introduction..................................................................................................................157
5.2.2 Mapping surface conductivity......................................................................................159
5.2.3 Regional soil mapping with AEM................................................................................160
5.2.4 Peeling away cover.......................................................................................................162
5.2.5 The DOI – decreasing exploration risk.........................................................................163
5.2.6 PhiD – understanding misfits........................................................................................165
5.2.7 Regional mapping of sedimentary facies......................................................................167
5.2.8 Mapping regional structure...........................................................................................169
5.2.9 Mapping regional geological surfaces..........................................................................170
5.2.10 References..................................................................................................................171
5.3 Mapping palaeovalley systems: Southern Callabonna Sub-basin (A. J. Fabris and
I. C. Roach)..........................................................................................................................173
5.3.1 Introduction..................................................................................................................173
5.3.2 Geological history and regional geology......................................................................173
5.3.3 Local geology: southwestern Callabonna Sub-basin....................................................174
5.3.4 Local geology: southeastern Callabonna Sub-basin.....................................................175
5.3.5 Methods........................................................................................................................178
5.3.6 Results..........................................................................................................................178
5.3.7 Discussion.....................................................................................................................189
5.3.8 Conclusion....................................................................................................................191
5.3.9 References....................................................................................................................192
5.4 Mapping palaeovalley systems: MacDonnell Creek and northern Flinders Ranges
area (I. C. Roach and S. Jaireth)...........................................................................................193
5.4.1 Introduction..................................................................................................................193
5.4.2 Geology and geomorphology.......................................................................................193
5.4.3 AEM investigations......................................................................................................194
5.4.4 Methods........................................................................................................................195
5.4.5 Interpretations from the Frome AEM Survey...............................................................197
5.4.6 Conclusions..................................................................................................................203
5.4.7 References....................................................................................................................204
5.5 Mapping basin architecture and salinity: A TEMPEST™ AEM interpretation of the
Poontana Trough, northwestern Lake Frome region (B. H. Michaelsen,
A. B. Marsland-Smith, P. D. Magarey, A. J. Fabris, I. C. Roach, T. Dhu, L. F. Katona
and J. L. Keeling).................................................................................................................205
5.5.1 Introduction..................................................................................................................205
5.5.2 Basin-wide aquifer salinity model................................................................................210
5.5.3 Results and discussion..................................................................................................214
5.5.4 Conclusions..................................................................................................................228
5.5.5 References....................................................................................................................230
5.6 Mapping Structures: Interpretation of the Frome AEM Survey for the Leigh Creek-
Marree region, South Australia (T. Wilson and I. C. Roach)...............................................231
5.6.1 Introduction..................................................................................................................231
5.6.2 Outline of regional geology..........................................................................................232
5.6.3 Methods........................................................................................................................233
5.6.4 Results..........................................................................................................................234
5.6.5 Discussion.....................................................................................................................241
5.6.6 Conclusion....................................................................................................................242
5.6.7 References....................................................................................................................242
5.7 Mapping structure-related mineral deposits: Gold deposits in the Nackara Arc and
Copper-Molybdenum prospects associated with the Anabama Granite (S. Jaireth)............243
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The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
and regional geology
5.7.1 Introduction..................................................................................................................243
5.7.2 AEM signatures of orogenic lode gold and porphyry copper-molybdenum deposits...246
5.7.3. Conclusions.................................................................................................................249
5.7.4 References....................................................................................................................250
5.8 Mapping geological surfaces: Benagerie Ridge resistive basement and basin stratigraphy
(I. C. Roach).........................................................................................................................251
5.8.1 Introduction..................................................................................................................251
5.8.2 Creating the model........................................................................................................253
5.8.3 Results and discussion..................................................................................................253
5.8.4 Conclusions..................................................................................................................258
5.8.5 References....................................................................................................................258

6 Summary and conclusions (I. C. Roach and S. Jaireth) ....................................259
6.1 Meeting the aims of the survey.............................................................................................259
6.1.1 Mapping Palaeovalley systems.....................................................................................259
6.1.2 Mapping basin architecture...........................................................................................259
6.1.3 Mapping sedimentary facies.........................................................................................260
6.1.4 Mapping geological structures......................................................................................260
6.1.5 Mapping geological surfaces........................................................................................260
6.1.6 Mapping groundwater resources...................................................................................261
6.1.7 Data collection and inversion products.........................................................................261
6.2 Implications for uranium systems.........................................................................................262
6.3 Implications for orogenic lode gold and porphyry copper-gold systems..............................263
6.4 References.............................................................................................................................264

7 Acknowledgements............................................................................................269

Appendix 1: Additional climate data ....................................................................271
Appendix 2: Summary of inversion products for the 400 m GA-LEI.....................275
Appendix 3: GA-LEI of TEMPEST Data (R. C. Brodie)...........................................278
A3.1 Introduction........................................................................................................................278
A3.2 Formulation........................................................................................................................278
A3.2.1 Coordinate System.....................................................................................................278
A3.2.2 System Geometry.......................................................................................................278
A3.2.3 Layered Earth.............................................................................................................280
A3.2.4 Data............................................................................................................................280
A3.2.5 Model Parameterisation.............................................................................................281
A3.2.6 Forward Model Derivatives.......................................................................................281
A3.2.7 Reference Model........................................................................................................282
A3.3 Objective Function.............................................................................................................282
A3.3.1 Data Misfit.................................................................................................................283
A3.3.2 Conductivity Reference Model Misfit.......................................................................284
A3.3.3 System Geometry Reference Model Misfit...............................................................284
A3.3.4 Vertical Roughness of Conductivity..........................................................................285
A3.4 Minimisation Scheme.........................................................................................................285
A3.4.1 Linearisation..............................................................................................................285
A3.4.2 Choice of the value of λ.............................................................................................286
A3.4.3 Convergence Criterion...............................................................................................287
A3.5 References..........................................................................................................................287
Appendix 4: GA-LEI output ASCII header information .........................................288
A4.1 Sample-by-Sample Inversion Conductivity Header...........................................................288
A4.2 Line-by-Line Inversion Conductivity Header....................................................................291
Appendix 5: Technical specifications of map projections ...................................295
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The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
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Figures

Figure 1.1: Location map of the Frome AEM Survey area.............................................................4
Figure 1.2: Mineral occurrences in the Frome AEM Survey area..................................................6
Figure 1.3: Uranium occurrences in the Lake Frome area..............................................................7
Figure 1.4: Geo-electrical Model 1.2. Eyre Formation palaeovalleys in Curnamona Province....11
Figure 1.5: Drape analysis of the Frome AEM Survey region......................................................12
Figure 1.6: Native title determinations and applications in the Frome AEM Survey area............14
Figure 1.6: Legend for Figure 1.6.................................................................................................15
Figure 1.7: Cartoon of flight line planning including overfly areas..............................................19
Figure 1.8: Final flight line spacings and infill areas for the Frome AEM Survey.......................20

Figure 2.1: 1:250 000 and 1:100 000 scale geological maps, Frome AEM Survey area..............25
Figure 2.2: Solid geology maps of the Frome area.......................................................................26
Figure 2.3: Time slices of geological provinces within the Frome AEM Survey area.................27
Figure 2.4: Regolith-landform mapping within or intersecting the Frome AEM Survey area......30
Figure 2.5: Publicly-available drill hole data within and adjacent to the Frome AEM
Survey area.............................................................................................................................35
Figure 2.6: Frequency versus depth histogram of all publicly-available drill holes.....................36
Figure 2.7: Exploration tenement status 2010-2012 over the Frome AEM Survey area..............37
Figure 2.8: Regional geophysical datasets available for the Frome AEM Survey area................39
Figure 2.9: Publicly-available AEM survey boundaries for the Frome AEM Survey area...........40
Figure 2.10: Location of seismic lines and associated magnetotelluric data................................42

Figure 3.1: Geological domains of the Curnamona Province.......................................................54
Figure 3.2: Conceptual model of the Broken Hill rift...................................................................54
Figure 3.3: Depth to basement image of the Curnamona Province...............................................55
Figure 3.4: Subdivisions of the Willyama Supergroup.................................................................56
Figure 3.5: First vertical derivative magnetic image of the Benagerie Ridge area.......................57
Figure 3.6: Location of the Frome AEM Survey compared to Neoproterozoic rocks..................59
Figure 3.7: Stratigraphic column of Neoproterozoic rocks...........................................................60
Figure 3.8: Paleozoic solid geology of the Frome AEM Survey area...........................................62
Figure 3.9: Mesozoic solid geology of the Frome AEM Survey area...........................................63
Figure 3.10: Geology and stratigraphy of the Leigh Creek coalfield............................................64
Figure 3.11: Generalised stratigraphy of the Cretaceous portion of the Eromanga Basin............65
Figure 3.12: Cenozoic stratigraphy of the Lake Frome area and Murray-Darling Basin..............66
Figure 3.13: Simplified surface geology of the Frome AEM Survey area....................................67
Figure 3.14: Cross-section of the Yarramba Palaeovalley at the Honeymoon uranium mine......68
Figure 3.15: Sketch of the Eyre Formation type section near Innamincka...................................69
Figure 3.16: Sketch of the stratigraphy of the Namba Formation outcrop....................................70
Figure 3.17: Stratigraphic logs of the Namba and Eyre formations at Oban................................71
Figure 3.18: Interpreted palaeovalleys of the southern Callabonna Sub-basin.............................72
Figure 3.19: Distribution of the Ninnerie Supersuite granites......................................................74
Figure 3.20: Physiographic regions of the Frome AEM Survey area...........................................80
Figure 3.21: MRVBF index image of the Frome AEM Survey area............................................81
Figure 3.22: Regolith materials map of a portion of the Frome AEM Survey area......................83
Figure 3.23: Examples of in situ regolith in the Frome AEM Survey area...................................84
Figure 3.24: Examples of in situ regolith in the Frome AEM Survey area...................................85
Figure 3.25: Examples of transported regolith in the Frome AEM Survey area...........................86
Figure 3.26: Ternary radiometric image of the Manunda Creek alluvial fan................................87
Figure 3.27: Large alluvial fans systems of the northern Flinders Ranges...................................88
Figure 3.28: Palaeovalley outlines and modern drainage systems of the northern Olary Spur.....89
Figure 3.29: Examples of colluvial regolith materials in the Frome AEM Survey area...............90
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The Frome airborne electromagnetic survey, South Australia: implications for energy, minerals
and regional geology
Figure 3.30: Contour banded colluvial sheetwash lobes near Mingary, SA.................................91
Figure 3.31: Aeolian sediments in or near the Frome AEM Survey area.....................................92
Figure 3.32: Examples of palaeolacustrine sediments in the Frome AEM Survey area...............92
Figure 3.33: Bioregions of the Frome AEM Survey area.............................................................95
Figure 3.34: Examples of vegetation communities within the Frome AEM Survey area.............96
Figure 3.35: Landscape evolution model for the Mount Painter Inlier.........................................98
Figure 3.36: Deformation history of the Curnamona Province.....................................................99
Figure 3.37: Drainage rearrangement and fault scarps................................................................103
Figure 3.38: Regolith-landform and geological components in the northern Flinders
Ranges-Mount Painter Inlier-Mount Babbage Inlier area....................................................103
Figure 3.39: Regolith-landform and geological components in the Olary Spur-Barrier
Ranges-southern Frome Embayment region........................................................................104
Figure 3.40: Regolith-landform and geological components in the Nackara Arc-
Murray-Darling Basin region...............................................................................................104
Figure 3.41: Uranium occurrences in the Frome AEM Survey area...........................................105
Figure 3.42: Faults, basement structures and uranium deposit locations in the Beverley area...111
Figure 3.43: Uranium source rocks and deposits in the northeastern Flinders Ranges-
northwestern Lake Frome area.............................................................................................112
Figure 3.44: Uranium source rocks and deposits in the Curnamona Province-southern
Callabonna Sub-basin area...................................................................................................114

Figure 4.1: Diagram of the 1D vertically smooth layered earth model used in the GA-LEI......130
Figure 4.2: Spatial extent of the LBL inversion..........................................................................132
Figure 4.3: An example of a geo-electrical model (1.2) from the Frome AEM Survey area......134
Figure 4.4: Georeferenced JPEG for a portion of line 1001002 (SBS GA-LEI)........................136
Figure 4.5: Colour conductivity scale bars for georeferenced JPEGs.........................................136
Figure 4.6: An example of SBS GA-LEI GOCADTM triangulated surfaces...............................137
Figure 4.7: A SBS GA-LEI multiplot for a section of line 1001002..........................................139
Figure 4.8: The AEM Go-Map (DOI grid).................................................................................140
Figure 4.9: Depth slices showing 0-5 m, 30-40 m, 80-100 m and 150-200 m............................142
Figure 4.10: SBS GA-LEI elevation slices.................................................................................143
Figure 4.11: FAS multiplot for line 2005301..............................................................................144
Figure 4.12: Location of conductivity-logged boreholes and flight lines...................................146
Figure 4.13: Scatter plots showing fiducial point comparisons for boreholes within
500 m and 1000 m of flight lines.........................................................................................148

Figure 5.1.1: Frome AEM Survey case study areas....................................................................155

Figure 5.2.1: 0-200 m conductance image of the Frome AEM Survey......................................158
Figure 5.2.2: 0-200 m conductance image and 0-5 m conductivity depth slice image...............159
Figure 5.2.3: Soil Atlas of Australia polygons on the 0-5 m conductivity depth slice................160
Figure 5.2.4: Sand dunes and playas in the northeast of the Frome AEM Survey area..............161
Figure 5.2.5: 200 m inversion product conductivity depth slices...............................................162
Figure 5.2.6: The DOI grid for the Frome AEM Survey............................................................163
Figure 5.2.7: Regional surface geology, 0-100 m conductance and detailed GA-LEI
conductivity sections near the MacDonnell Creek uranium prospect..................................165
Figure 5.2.8: SBS GA-LEI conductivity section and corresponding PhiD graph.......................166
Figure 5.2.9: PhiD grid for the Frome AEM Survey..................................................................167
Figure 5.2.10: Comparison of LBL GA-LEI and SBS GA-LEI with different colour stretches.168
Figure 5.2.11: Validation of SBS GA-LEI conductivity sections with drill hole stratigraphy...169
Figure 5.2.12: Ternary radiometric and conductance image, Murray-Darling Basin.................170
Figure 5.2.13: Resistive basement GOCADTM model, northwestern Murray-Darling Basin.....171

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