Geological Survey of South Australia | RIS2014 Broken Hill Industry Presentation

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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.

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  • This case study is featured in more detail in the CRC LEME regional explorer’s guide for the SW Thomson Orogen. This can be downloaded from http://crcleme.org.au/Pubs/guides.
    These tors of weathered Tibooburra Granodiorite occur on the SW margin of the Tibooburra town common (just NE of the Cameron Corner TO frm the Silver City Hwy). Its this irregular landscape that acted as an excellent physical depositional trap for detrital Au that was transported in Mesozoic palaeodrainage systems.
  • Only known primary Au occurrences are within veins and associated alteration systems of the Warratta Inlier. Other primary sources (eg provenance for Tibooburra and Mount Browne placers) are likely under basin cover to the west
  • The inliers and their margins in this area provide interesting uplifted ‘windows’ through he surrounding deep cover. Note also that pretty well all of the drill-holes from which this figure is derived are water bores, rather than mineral exploration drill-holes. There have effectively been NO deep cover mineral exploration drill holes in the area of this figure.
  • This is a photo of Quarry Hill near Tibooburra. It shows weathered Devonian granodiorite in the foreground. The sediment of the hill consists of Early Jurassic to Early Cretaceous, fluvial Algebuckina Sandstone equivalent gravels and sands (unconformably overlying the weathered granodiorite), which are overlain by Early Cretaceous marginal marine sands equivalent to the Cadna-owie Formation. The basal fluvial gravels host detrital Au grains (shown in inset photo). Lithological log on right is for the section exposed in the quarry excavated into this hill to help build the Family Hotel and other buildings in the nearby Tibooburra ‘CBD’.
  • A reconstruction of the Late Jurassic palaeolandscape, which is associated with detrital Au dispersion. It was this landscape that interacted with the weathered Au-bearing bedrock in the region, whereas later (Au-poor) basin sediments reworked a landscape where Au-bearing bedrock was buried.
  • These vectors are from palaeocurrent measurements (mostly cross-bedding) associated with field exposures of basal Mesozoic gravels and sands. Each arrowed site is based on between 30-100 measurements from field sites.
  • Palaeoflow from W to E and then down to SE in the late Jurassic – Early Cretaceous. The emergent bedrock ridges acted as an impediment to palaeoflow, thereby providing sites for gold lodgement. Previous exploration models searched the bedrock ridges of the Tibooburra Inlier for a primary Au source, however this model supports a provenance to the west of the inlier. Palaeoflow would have continued broadly to the east into the Bulloo Embayment of the Eromanga Basin.
  • So the obvious question now becomes, ‘what occurs to the west of the Tibooburra Inlier and other major placer Au occurrences in the area?”. The basin cover in these areas approaches and exceeds 100 m and there have been NO exploration drill holes in these areas (typical of the deep basin exploration frontier in many parts of Australia). The base image here is a processed Landsat 7 image provided by the NSW DPI (see Hill et al 2009 for further details)
  • So lets look at some of the regional geophysical imagery of these deeply buried target areas .... hmmm, interesting....
  • Geological Survey of South Australia | RIS2014 Broken Hill Industry Presentation

    1. 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. 2. Murphy’s “Haystacks” (Photo: S.Hill) Pre-competitive Geoscience Data… finding mineral system “Haystacks”
    3. 3. Moon Plain, Stuart Shelf, SA (Photo S.Hill) Deep Cover Exploration Impediment…
    4. 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. 5. Be a Cover Lover! 5
    6. 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. 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. 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. 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. 10. Tunkillia biogeochemical model (Lowrey & Hill, in prep.) Central Gawler Craton Deep cover Plant biogeochemistry
    11. 11. UoA Honours students Black oak sampling April 2009 Minotaur Exploration Drilling April 2010 Tunkillia, Gawler Craton
    12. 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. 13. After R E Smith & B Singh, 2007
    14. 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. 15. IOCG – Porphyry – Epithermal Continuum (Claire Wade, GSSA) Into the overlying cover???
    16. 16. Curnamona Province dispersion haloes shown on radiometrics image 16 • Mt Painter • Broken Hill 50 km
    17. 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. 18. Catchment headwaters within Barrier Ranges Mundi Mundi Plains Umberumberka Reservoir Umberumberka Creek - Broken Hill (Charlotte Mitchell, DET CRC)
    19. 19. Catchment headwaters within Barrier Ranges Mundi Mundi Plains Umberumberka Reservoir Umberumberka Creek - Broken Hill (Charlotte Mitchell, DET CRC)
    20. 20. Mundi Mundi Plain • Lateral dispersion and reaccumulation • Important balance between processes of erosion, sedimentation and weathering / soil formation
    21. 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. 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. 23. Trinity Well type section, Marree 1:250k mapsheet 23
    24. 24. Trinity Well Reference Section 24
    25. 25. Deep cover atlas of SA (DET CRC) … 25
    26. 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. 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. 28. CASE STUDY 1: Tibooburra Au provenance... Tors of Tibooburra Granodiorite (photo S.Hill)
    29. 29. Tibooburra-Milparinka Au-fields (Thomson Orogen NSW) From Hill et al 2009
    30. 30. Tibooburra-Milparinka Au-fields Depth of Basin Cover (Mesozoic and younger)
    31. 31. Radial ‘shedding’ model Tibooburra Inlier No! This applies to contemporary drainage but not the Mesozoic system Mesozoic hinterland-basin geochemical reconstruction needed!
    32. 32. Au hosted in basal Mesozoic sediments
    33. 33. (Hill, 2005) Late Jurassic (basal Mesozoic) palaeolandscape
    34. 34. Au-bearing Basal Mesozoic palaeocurrent vectors Tibooburra Inlier (Hill et al 2009)
    35. 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. 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. 37. Deeply Buried Au Provenance? Tibooburra Inlier NSW GS, 1VD magnetics Mt Browne Inlier
    38. 38. CASE STUDY 2: The Pinnacles …
    39. 39. Looking South down Pine Creek from Middle Pinnacle Pinnacles Mine Pine Creek South Pinnacle
    40. 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. 41. Get a PhD student to work on it – Karen Hulme
    42. 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. 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. 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. 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. 46. It was time to dig… Sarah ‘Gibbo’ Gibbons (earnest, hard-working CRC LEME Honours student) Photos: Karen Hulme
    47. 47. Pinnacles - lodes extensions Photographs: Steve Hill Mineralisation continues near surface but below main road!
    48. 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. 49. Kangaroo Prospectors
    50. 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. 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. 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. 53. CASE STUDY 3: Four Mile U (Steve Hore & Steve Hill, GSSA)
    54. 54. Four Mile East Dead Tree Section Four Mile Creek Four Mile West Beverley
    55. 55. F Four Mile East Dead Tree Section – Eyre Formation sample locations 20m
    56. 56. Four Mile West: Deadtree Section Namba Fm Pedogenic Silcrete Eyre Fm Bulldog Shale & Cadna-owie Fm Saprolite
    57. 57. (Hill, 2005) Late Jurassic
    58. 58. Mesozoic Glaciations • Widespread dispersal of U-rich detritus in Early Cretaceous glaciers Recorder Hill
    59. 59. Mesozoic Glaciations • Important context for Four Mile West U deposit Palaeoredox interfaces in Mesozoic diamictite at Deadtree section (Hore & Hill, 2009)
    60. 60. (Hill, 2005) Early Cretaceous
    61. 61. Mt Babbage Inlier (U-rich granites) Oxidised Bulldog Shale
    62. 62. Mt Babbage Inlier U-rich bedrock Mesozoic sediments
    63. 63. (Hill, 2005) Palaeogene
    64. 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. 65. Eyre Formation (palaeo-redox fronts) – Important U host (Four Mile, Honeymoon, Goulds Dam, Oban)
    66. 66. Namba Fm (Miocene) – hosts Beverley
    67. 67. Namba Formation Top of Namba Fm Top of Saprolite (Wooltana Volcanics) Willawortinna Fm outwash gravels
    68. 68. (Hill, 2005) Neogene
    69. 69. Proterozoic basement Willawortina Ftm Eyre Formation geologists
    70. 70. ~ 5 km Four Mile East Four Mile West ? ?
    71. 71. ~ 5 km
    72. 72. ~ 5 km Preserved Tertiary Exposed Mesozoic
    73. 73. Four Mile Stream Sediments (GSSA Radiometrics) NB. High U content of detritus from ranges overlying basin prospective for buried sedimentary U
    74. 74. Four Mile Prospect soil U Neimanis et al 2007
    75. 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. 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. 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. 78. FOUR MILE BIOGEOCHEMISTRY: TARGET SPECIES Allows subsurface access to culturally and environmentally sensitive sites River Red Gum Inland tea-tree
    79. 79. Neimanis, Hill & Hore, 2007 Inland Tea-tree shows similar results to stream sediments! (shallow alluvial aquifer)
    80. 80. Neimanis, Hill & Hore, 2007 River red gum shows deeper mineralisation expression along structures (deeper fractured aquifer)
    81. 81. U2 / Th river red gum leaves
    82. 82. Ant biogeochemistry (Iridomyrmex spp.) Meat Ant Distribution www.ento.csiro.au/science/ants Courtesy Deanne Gallasch
    83. 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. 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. 85. Roo Poo Biogeochemistry (McMahon & Hill, 2007)
    86. 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. 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. 88. Plant biogeochemistry providing surficial expression of sub-surface chemistry Biogeochemistry
    89. 89. → Cost and Time efficient subsurface chemical information (help focus and rank drilling targets)
    90. 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. 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. 92. Photo: Steve Hill92 Western Gawler Craton – Eucla Basin….
    93. 93. South Australian Mineral Exploration Licences January 2004 September 2013
    94. 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. 95. Western Gawler / Eucla Basin Continental Seismic Transect (TMI backdrop) 95 Coompana Anomaly Fowler Domain Gawler Ranges
    96. 96. Eucla Basin – Gawler Craton MT
    97. 97. Western Gawler / Eucla Basin Regional Geophysics • Magnetics • Radiometrics Older airborne surveys 1600-3000 line spacing (did not always collect radiometrics)
    98. 98. Western Gawler / Eucla Basin Geochemistry / Biogeochemistry • Regional Geochemistry – 2013-14 • Hydrogeochemistry • Soil • Calcrete • Biogeochemistry ~450 plant samples ~170 sample sites
    99. 99. 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
    100. 100. Thank-you…. Yours Lovingly Steve (Your Cover Lover Brother) 101
    101. 101. 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.

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