Neoproterozoic stratigraphic revisions to key drillholes in the Amadeus Basin – implications for basin paleogeography and petroleum and minerals potential

Verity J Normington and Chris J Edgoose NTGS The Amadeus Basin • Extensive (~170,000 km2) Neoproterozoic – Devonian intracratonic sedimentary basin • Basement comprised of both Musgrave Province (south) and Arunta Region (north) • Affected by major intracratonic orogenic events the (580-530 Ma) and the Orogeny (450- 300 Ma) • Largely unexplored terrane

Georgina Basin Ngalia Basin Arunta Region

Eromanga Basin Musgrave Province Systematic relogging of Neoproterozoic succession in selected drillholes Project scope • Application of new/redefined Neoproterozoic units to selected drillholes – Based on NTGS field study in the NE and mapping in the central part of basin reported previously at AGES (Normington et al 2015, Donnellan and Normington 2017) Revised Neoproterozoic succession

2013 stratigraphy (Edgoose 2013) Current stratigraphy (Normington 2018) Project contributions • Updated Neoproterozoic stratigraphy in selected drillholes across the basin – Improves correlations – Ensures future studies use the most up to date stratigraphy • Improves understanding of unit distribution across the basin – in particular the Wallara and Aralka formations • Important to petroleum and mineral systems – Increased recognition of continuous distribution of black, organic rich shales (often with sulphides) within previously recognised petroleum and mineral system significant units Which drillholes and where

BMR Alice Springs 27 CPDD001 CPDD002 LA05DD01 FINKE 1 CPDD003

BR05DD01 WALLARA 1

Investigations Neoproterozoic complete or ongoing Olympic/Pertatataka/Julie Areyonga/Aralka Referenced drillholes Bitter Springs/ Heavitree Summary of changes to stratigraphy BMR Alice Springs 27

BR05DD01 CPDD001-003

Julie FM

Pertatataka FM

Pioneer SST Olympic FM Aralka FM

Areyonga FM Wallara FM

Bitter Springs GP original logged stratigraphy 27 revised logged stratigraphy CPDD003 CPDD002 CPDD001 missing stratigraphy Springs BMR BMR Alice BR05DD01 Julie FM

Pertatataka Wallara Formation FINKE 1 FM • Formerly ‘finke beds’ originally WALLARA 1 Pioneer SST identified in drillcore in Finke 1 Olympic FM (Gorter 1983) Silcrete – Wallara Formation Aralka FM

• NTGS has recognised in outcrop along Areyonga FM the N and NE margins and central and Wallara FM western (GSWA) Amadeus Basin Bitter • Surface expression often only Springs GP comprises calcrete and silcrete • Now formalised as Wallara Formation • Significant global marker unit Calcrete – Wallara Formation • Cryogenian, based on acritarch Cerebrosphaera buickii (Grey et al 2011) • Diagnostic stromatolite Bacialia burra • New type section, Wallara 1 DH Julie FM

Pertatataka Wallara Formation FINKE 1 FM • Formerly ‘finke beds’ originally WALLARA 1 Pioneer SST identified in drillcore in Finke 1 Olympic FM (Gorter 1983) Type section, Aralka FM • NTGS has recognised in outcrop along Wallara 1 DH Areyonga FM the N and NE margins and central and Wallara FM Bitter western (GSWA) Amadeus Basin Springs GP • Surface expression often only comprises calcrete and silcrete • Now formalised as Wallara Formation • Significant global marker unit Organic shale • Cryogenian, based on acritarch and oil staining Cerebrosphaera buickii (Grey et al 2011) Type section, Wallara 1 DH • Diagnostic stromatolite Bacialia burra • New type section, Wallara 1 DH

Baicalla burra Julie FM Distribution of Wallara Formation Pertatataka FM

(‘finke beds’) Pioneer SST Olympic FM • Prior to formal definition to the Wallara Formation, the Aralka FM finke beds were only known in 3 drillholes (Edgoose 2013) Areyonga FM Wallara FM Bitter Springs GP Julie FM

BR05DD01 Wallara Formation Pertatataka CPDD003 FM in drillhole Wallara 1 Pioneer SST Olympic FM • Increased distribution now recognised in Aralka FM Areyonga FM BR05DD01, CPDD003 and Wallara-1 Wallara FM Bitter • Previously logged as Johnnys Creek or Loves Springs GP Creek formations (Bitter Springs Group) or Pertatataka Formation • Reassigned on the basis of diagnostic Baicalia burra stromatolites (by GSWA) and lithofacies • Contrasting to outcrop it comprises dominantly black shales and red and green siltstones in drillholes – Sandstone and carbonates lithofacies only present in the Wallara-1 DH type section The Wallara Formation in BR05DD01

Typical Wallara Formation - Stromatolitic carbonate BR05DD01 - Calcareous siltstone - Organic-rich black shales - Carbonates The Wallara Formation in BR05DD01

Typical Wallara Formation - Carbonates BR05DD01 - Red (and green) siltstones - calcareous siltstone - Organic-rock black shales Mineralogical comparisons – BR05DD01

Areyonga The Wallara Formation can be Fm Johnnys identified in hyperspectral analysis Aralka Fm Wallara Fm Creek Formation (Hylogger data)

2nd row (SWIR mineralogy) Dolomite CalciteCalcite Phengite (mica mineral) Aspectral (likely black/dark grey shales) 3rd row (TIR mineralogy) Carbonate minerals Smectites (clay mineral) Silica WhiteWhite Micas micas There is a distinct difference between the bulk mineralogy of the Wallara Formation and surrounding Areyonga and Johnnys Creek formations

For Hylogger data see Smith 2013, NTGS Rec 2013-007 Julie FM

Previous distribution Pertatataka of Wallara Formation FM Pioneer SST Olympic FM Aralka FM

Areyonga FM Wallara FM Bitter Springs GP Julie FM

Current distribution Pertatataka of Wallara Formation FM • Has a basin-wide distribution Pioneer SST Olympic FM • Globally significant – Cryogenian global marker unit Aralka FM • Important new information for Neoproterozoic palaeogeographic Areyonga FM reconstructions of the Amadeus Basin and the Centralian Wallara FM Superbasin Bitter • Palaeogeographic reconstructions are complicated by tectonic Springs GP overprinting of Petermann and Alice Springs orogenies and halotectonics (Weisheit and Donnellan 2018) and glacial scouring

Haines and Allen 2014. Julie FM

Aralka Formation Pertatataka FM • Exposures restricted to the Pioneer SST N and NE margins and central basin Olympic FM Limbla Mbr • Dominantly recessive siltstone and shales - Aralka FM Ringwood Mbr most exposures comprise carbonate Aralka FM Areyonga FM Wallara FM Ringwood Member and siliciclastic Limbla Bitter Member Springs GP Type section – SE Olympic Bore

Ringwood Member – Limbla Member – Type section Siltstone – Aralka Reference area – Limbla – Hi Jinx Syncline Formation Syncline Julie FM

Distribution of Aralka Formation Pertatataka Including Ringwood and Limbla Members FM

Pioneer SST • Distribution from surface exposures Olympic FM Limbla Mbr Aralka FM and Wallara 1 Ringwood Mbr Areyonga FM Aralka FM Aralka • Rapidly thins away from the NE Wallara FM Bitter margin Springs GP Julie FM

The Aralka Formation in drillholes Pertatataka • Increased distribution now recognised in FM Pioneer SST BR05DD01, CPDD001, CPDD002 and Olympic FM Limbla Mbr Wallara-1 Aralka FM Ringwood Mbr

Aralka FM Aralka Areyonga FM • Previously logged as Pertatataka Wallara FM Bitter Formation or Areyonga Formation Springs GP • Mostly black shales and siltstones ± sulphides • Sulphides not previously reported in BR05DD01 • Ringwood Member recognised in BR05DD01 is the most westerly

occurrence in NT, supported by BR05DD01 biostratigraphic observations CPDD001-003 (Allen et al in prep) WALLARA 1 Limbla Aralka Formation in drillholes Syncline CPDD003 organic-rich, pyritic shale BR05DD01 CPDD001-003

BR05DD01 intraclast breccia

Limbla Syncline intraclast breccia CPDD001 lenticular bedding Aralka Formation in drillholes CPDD003 black, organic-rich shale/siltstone BR05DD01 CPDD001-003

Pyrite is variable in content and typically disseminated (as seen in CPDD002, 003 and BR05DD01)

CPDD003 disseminated pyrite within black shales Julie FM Ringwood Member – BR05DD01 Pertatataka FM

Pioneer SST Olympic FM Aralka Fm Ringwood Mbr Limbla Mbr Aralka FM Ringwood Mbr Areyonga FM Aralka FM Aralka Wallara FM Bitter Springs GP

Black shale/siltstone

Tungussia inna stromatolite

Atilyana fennensis Tungussia inna stromatolite stromatolites Mineralogical Comparisons – BR05DD01 Ringwood Mbr The Ringwood Member is Aralka Fm Aralka Fm recognisable in hyperspectral analysis (Hylogger data)

2nd row (SWIR mineralogy) Dolomite CalciteCalcite Phengite (mica mineral) Muscovite

3rd row (TIR mineralogy) Carbonate minerals Smectites (clay mineral) Silica WhiteWhite Micas Micas There is a distinct difference between the bulk mineralogy of the Aralka Formation and the Ringwood Member.

For Hylogger data see Smith 2013, NTGS Rec 2013-007 Julie FM

Previous distribution Pertatataka FM of Aralka Formation Pioneer SST Olympic FM Limbla Mbr Aralka FM Ringwood Mbr Areyonga FM Aralka FM Aralka Wallara FM Bitter Springs GP Current distribution of Aralka Formation Julie FM Pertatataka • Has a basin-wide distribution FM • Thins in basin centre then thickens significantly to the west Pioneer SST • As for the Wallara Formation, this is important new information for Olympic FM Neoproterozoic palaeogeographic reconstructions of the Amadeus Aralka FM Basin and the Centralian Superbasin Areyonga FM • Palaeogeographic reconstructions are complicated by tectonic Wallara FM Bitter overprinting of Petermann and Alice Springs orogenies and Springs GP halotectonic effects (Weisheit and Donnellan 2018) and it is a post- glacial unit

Haines and Allen 2014. Pertatataka or Aralka Formation? Based on stratigraphic revisions Pertatataka Formation to Aralka and Wallara formations in CPDD001,002 and 003 and BR05DD01, Julie FM Pertatataka could the Pertatataka Formation in FM

other drillholes actually be the Pioneer SST Johnnys Creek-Aralka formation Olympic FM succession? Aralka FM Areyonga FM BR05DD01 CPDD001-003 Wallara FM

Bitter Springs GP Julie FM

Pertatataka or Aralka Formation? Pertatataka FM

Pioneer SST Olympic FM Aralka FM

Areyonga FM Wallara FM Bitter Springs GP vs

Pertatataka Fm Aralka Fm Aralka Fm Aralka Fm BMR Alice Springs 27 BR05DD01 CPDD001 CPDD002 Julie FM

Pertatataka or Aralka Formation? Pertatataka FM

Pioneer SST Olympic FM

Aralka FM

Areyonga FM Wallara FM

Bitter Springs GP

*

*Pertatataka Formation as reported in well completion reports Pertatataka or Aralka Formation? Julie FM Pertatataka • Aralka Formation was originally defined as a member of the FM Pertatataka Formation (Wells et al 1967) Pioneer SST • Preiss et al (1978) defined the Aralka Formation as distinct Olympic FM unit Aralka FM Areyonga FM In these drillholes, the Pertatataka Fm is reported to Wallara FM Bitter • Directly overlie the Bitter Springs Group Springs GP • Described as sandstones, siltstone (red, green, black, grey), carbonates and pebbly sandstones (possible Areyonga Formation)

• Most of these wells were drilled and logged in the 1960s using the Wells et al (1967) stratigraphy Implications for mineral and petroleum prospectivity • Basin-wide distribution of organic-rich shales • Presence of sulphides Julie FM • Potential petroleum source rocks Pertatataka • Wallara Formation FM

• One of the most promising reservoirs in the Neoproterozoic (Munson Pioneer SST 2014) Olympic FM • Has oil shows in Finke-1 (Marshall et al 2007) Aralka FM • Has no permeability and little remaining intergranular porosity Areyonga FM (Marshall et al 2007) Wallara FM • Aralka Formation Bitter • Has strong petroleum system indicators with high TOC levels in a Springs GP number of wells (Marshall 2004) • Shows strong source rock characteristics and has (or could) generate gas with some subordinate oil potential (Munson 2014) • Pertatataka Formation • is a proven petroleum source (Munson 2014) • Mt Charlotte-1 and Ooraminna-1 – type III kerogen shows (McKirdy 1977) • Wallara-1 and BR05DD01 have oil stains (Geowest 1990, Ambrose et al 2010). This has now been recognised as Aralka Formation Revisiting the key points Revising the stratigraphy of selected drillholes across the basin in combination with new surface mapping and observations has lead to • An increased known distribution of units across the basin • An increased understanding of the thickness variations in units • Recognition of lithological features that are potentially significant to mineral and petroleum systems • such as organic-rich potential source rocks and sulphide occurrences References Allen HJ, Grey K and Haines PW, in prep. The Cryogenian Aralka Formation, Amadeus Basin: a basin-wide biostratigraphic correlation. Geological Survey of Western Australia Record. Ambrose GJ, Dunster JN, Munson TJ and Edgoose CJ, 2010. Well completion reports for NTGS stratigraphic drillholes LA05DD01 and BR05DD01, southwestern Amadeus Basin. Geological Survey, Record 2010-015. Donnellan N and Normington VJ, 2017. Towards a revised stratigraphy for the Neoproterozoic and probable early Cambrian in the central Amadeus Basin, Northern Territory: in ‘Annual Geoscience Exploration Seminar (AGES) Proceedings, Alice Springs, Northern Territory, 28–29 March 2017’. Northern Territory Geological Survey, Darwin. Edgoose CJ, 2013. Chapter 23 - Amadeus Basin: in Ahmad M and Munson TJ (compilers), 'Geology and mineral resources of the Northern Territory.' Northern Territory Geological Survey, Special Publication 5. Geowest Pty Ltd, 1990. Wallara No. 1 Well Completion Report. Indigo-Oil Pty Ltd – Sirgo Exploration Incorporated. Northern Territory Geological Survey, Open File Petroleum Report PR1990-101. Gorter JD, 1983. Finke No.1 well completion report. Pancontinental Petroleum Ltd, PPL Report 96. Northern Territory Geological Survey, Open File Petroleum Report PR1984- 0015. Grey K, Hill AC and Calver CR, 2011. Biostratigraphy and stratigraphic subdivision of the Cryogenian successions of Australia in a global context. The geologic record of Neoproterozoic glaciations. E. Arnaud, G. P. Halverson and G. Shields-Zhoa, Geological Society of London. Memoirs 36: 113-134. Haines PW and Allen HJ, 2014. Geology of the Boord Ridges and Gordon Hills: key stratigraphic section in the western Amadeus Basin, Western Australia. Geological Survey of Western Australia Record 2014/11. McKirdy, DM, 1977. The diagenesis of microbial organic matter; a geochemical classification and its use in evaluating the hydrocarbon-generating potential of Proterozoic and Lower Palaeozoic sediments, Amadeus Basin, central Australia. PhD thesis, Australian National University, Canberra. Marshall TR, 2003. Petroleum systems and source rocks in the Amadeus Basin, Northern Territory: in Cowie M (editor). ‘Queensland 2003 exploration and development.’ Petroleum Exploration Society of Australia (Qld/NT) 2003 Symposium, 37–42. Marshall TR, 2004. Review of the source rocks in the Amadeus Basin. Northern Territory Geological Survey, Record 2004-008 Munson TJ, 2014. Petroleum geology and potential of the onshore Northern Territory, 2014. Northern Territory Geological Survey, Report 22. Normington VJ, 2018. Revised stratigraphy of drillholes CPDD001, CPDD002 and CPDD003, Pipeline Prospect, northeast Amadeus Basin, Northern Territory. Northern Territory Geological Survey, Record 2017-015. Normington VJ and Donnellan N, in review. Characterisation of the Neoproterozoic stratigraphy of the northeast Amadeus Basin, Northern Territory, Northern Territory Geological Survey, Record. Normington VJ, Donnellan N, Edgoose CJ and Kositcin N, 2015. Neoproterozoic evolution of the Amadeus Basin; evidence from sediment provenance and mafic magmatism: in ‘Annual Geoscience Exploration Seminar (AGES) 2015. Record of abstracts’. Northern Territory Geological Survey, Record 2015-002. Normington VJ and Edgoose CJ, 2015. Revised stratigraphy of drillhole BMR Alice Springs 27, northeast Amadeus Basin, Northern Territory. Northern Territory Geological Survey Technical Note 2015-003. Normington VJ, Edgoose CJ, Haines PW, Allen HJ and Grey K, in prep. Revised stratigraphy for NTGS stratigraphic drillholes LA05DD01 and BR05DD01, southwestern Amadeus Basin. Northern Territory Geological Survey, Record. Preiss, W. V., M. R. Walter, R. P. Coats and A. T. Wells (1978). Lithological correlations of Adelaidean glaciogenic rocks in parts of the Amadeus, Ngalia, and Georgina basins.BMR Journal of Australian Geology and Geophysics 3: 43-53. Roe LE, 1991. Petroleum Exploration in the Amadeus Basin: in Korsch RJ and Kennard JM (editors) ‘Geological and geophysical studies in the Amadeus Basin, central Australia’. Bureau of Mineral Resources, Australia, Bulletin 236, 463 – 476. Smith BR, 2013. Drillhole report for BR05DD01, Amadeus Basin, Northern Territory: National Virtual Core Library NTGS Node: HyLogger 3–7. Northern Territory Geological Survey, Record 2013-007. Wells AT, Forman DJ and Ranford LC, 1965. The Geology of the north-western part of the Amadeus Basin, Northern Territory. Bureau of Mineral Resources, Australia, Report 85. Wells AT, Ranford, LC, Stewart AJ, Cook PJ and Shaw RD, 1967. Geology of the north-eastern part of the Amadeus Basin, Northern Territory. Bureau of Mineral Resources, Australia, Report 113.