AGES 2021 Proceedings, NT Geological Survey

Update on geological mapping in the central and western Amadeus Basin Charles Verdel 1,2, Anett Weisheit 1, Nigel Donnellan 1 and Christine Edgoose 1 Over the last several years, the geology interpretation based on previous geology maps, and Geological Survey (NTGS) has been conducting mapping airborne magnetic, gravity and drillhole data. This project projects focused on the central and western parts of the identified, for the first time, the prevalence of faulting and Northern Territory’s portion of the Amadeus Basin. Specific fault-related folding across a large part of the central and goals of these projects include refined understanding of western Amadeus Basin. Faulting in this region is largely the structural geology of the region, as well as reconciling attributable to shortening during the late Neoproterozoic to Neoproterozoic stratigraphic nomenclature between Cambrian Petermann Orogeny (eg Raimondo et al 2010) and the eastern and western Amadeus Basin. The projects the mid-Palaeozoic Orogeny (eg Haines et al are now reaching their conclusion and will culminate 2001). The Petermann Orogeny resulted in a north-vergent, with five new maps: a 1:500 000-scale solid geology thick- and thin-skinned fold-and-thrust belt in the southern map covering the western part of the Northern Territory and central parts of the Amadeus Basin. Deformation during portion of the Amadeus Basin (Weisheit 2021), second the Petermann Orogeny was responsible for a series of edition 1:250 000-scale geological maps of HENBURY 3 unconformities referred to as the Petermann unconformity (Donnellan et al in prep), LAKE AMADEUS (Verdel et al (an example of the Petermann unconformity is illustrated in prep) and BLOODS RANGE (Verdel et al in prep), and in Figure 2a), which forms an important seismic horizon a first edition 1:100 000-scale Henbury Special geological across much of the Amadeus Basin (eg Menpes et al 2018). map (Donnellan and Normington in prep; Figure 1). The The younger Alice Springs Orogeny was south-directed 1:500 000 map covers ~150 000 km2 (including more than and pervasive in the southern Aileron Province, Warumpi half of the total extent of the Amadeus Basin), and the new Province and northern part of the Amadeus Basin. Some 1:250 000 maps cumulatively cover ~50 000 km2. Some of Petermann Orogeny structures were reactivated during the the major outcomes from the geological mapping projects Alice Springs Orogeny. Both Petermann Orogeny and Alice are summarised below. Springs Orogeny structures generally trend northwest– southeast, and they are cut by a series of northeast–southwest- West Amadeus Basin 1:500 000 solid geology striking reverse faults that formed late in the Alice Springs interpretation Orogeny (Isles and Rankin 2013, Weisheit 2021). Throughout the west Amadeus Basin map area, the clearest surface The west Amadeus Basin solid geology interpretation evidence for deformation attributable to the Petermann and (Weisheit 2021) covers the central and western parts of the Alice Springs orogenies are northwest–southeast-elongate NT portion of the Amadeus Basin, parts of the Aileron doubly-plunging folds (eg Forman 1963). and Warumpi provinces (eg Scrimgeour 2013a and b) to the north of the basin, and part of the Musgrave province Central Amadeus Basin 1:250 000 and 1:100 000 (eg Close 2013) to the south (Figure 1). The map is a solid geological mapping (HENBURY and Henbury Special)

1 Northern Territory Geological Survey, GPO Box 4550, Darwin HENBURY lies in the central part of the Amadeus Basin NT 0801, (Figure 1), a key region for linking the stratigraphic 2 Email: [email protected] 3 Names of 1:250 000 and 1:100 000 mapsheets are shown in nomenclature of the Neoproterozoic succession used for large and small capital letters respectively, eg BLOODS the northeastern part of the Amadeus Basin (eg Areyonga, RANGE, Henbury. Aralka, Olympic, and Pertatataka formations; eg Edgoose

22°S Murraba Basin Murraba Basin Georgina Basin Amadeus Aileron Province Basin Ngalia Basin Aileron Province

Kiwirrkurra WESTERN AUSTRALIA 23°S TERRITORY NORTHERN es Aadeus asin Irindina 100 000 Canning Basin Kintore Province Warumpi Province Alice Springs Hermannsburg 24°S Amadeus Amadeus Basin Basin Road Amadeus Basin Canning Basin HENBURY S ANGE AE AAES EN SPECIAL N 25°S 120 000 120 000 120 000 1100 000 Docker River Pedirka () Basin Yulara Officer Eromanga Basin Eromanga Basin

126 ° E Basin Musgrave Province

26°S 127 °30’ E 129 ° E 130 °30’ E 132 ° E 133 °30’ E 135 ° E 136 °30’ E Figure 1. Extents of new NTGS mapping projects in the western part of the NT portion of the Amadeus Basin. Background image shows shaded relief (Morgan-Wall 2020) of the Amadeus Basin and surrounding area.

© Northern Territory of Australia 2021. With the exception of government and corporate logos, and where otherwise noted, all material in this publication is provided under a Creative Commons Attribution 4.0 International licence (https://creativecommons.org/licenses/by/4.0/legalcode). 75 AGES 2021 Proceedings, NT Geological Survey

2013, Normington and Donnellan 2020) with that used in Sandstone of the northeastern Amadeus Basin. The central, southern and western portions (Inindia and Winnall overlying Winnall beds have been subdivided into six beds; eg Wells et al 1963, Jackson et al 1984). Outcrops of the formations (Quandong Conglomerate, Breaden, Gloaming, former Inindia beds on HENBURY have now been identified Froud, Liddle and Puna Kura Kura formations), which as belonging to the Tonian Wallara Formation (Figure 2b), comprise the new Winnall Group (Figure 2d–f; Donnellan Cryogenian Areyonga and Aralka formations (Figure 2c), and Normington 2017). These strata seem to correlate with and Cryogenian to Ediacaran Olympic Formation/Pioneer Ediacaran rocks (eg Pertatataka Formation, Julie Formation a b

c d

e f

Figure 2. Field photographs from the Amadeus Basin. (a) Angular unconformity (‘Petermann unconformity’) between underlying Ediacaran Liddle Formation and overlying Ordovician Stairway Sandstone in the southeastern part of LAKE AMADEUS. (b) Domical stromatolite of Wallara Formation (formerly mapped as Inindia beds) in HENBURY. (c) Characteristic festoon cross-stratification in sandstone of the Cryogenian Limbla Member of Aralka Formation, HENBURY. (d) Quandong Conglomerate, a lower part of Winnall Group, HENBURY. (e) Microbially-induced sedimentary structures (Kinneyia) from the Ediacaran Gloaming Formation, HENBURY. (f) Clay galls within Gloaming Formation, HENBURY. Hammer is 30 cm long. (Continued on next page).

76 AGES 2021 Proceedings, NT Geological Survey and lower Arumbera Sandstone) of the northeastern northwest–southeast-trending folds described above. The Amadeus Basin (Donnellan and Normington 2017, Verdel Henbury Special 1:100 000 map is thus being prepared to et al 2020). HENBURY also includes Palaeozoic strata illustrate the complexity of this area at a suitable level of (Figure 2g) that range in age from Cambrian to Devonian. detail. The southeastern part of HENBURY is a particularly structurally-complex area, which departs considerably from Western Amadeus Basin 1:250 000 geological mapping the overall central and western Amadeus Basin pattern of (LAKE AMADEUS and BLOODS RANGE)

g LAKE AMADEUS and BLOODS RANGE are located to the west of HENBURY (Figure 1). Like HENBURY, Amadeus Basin strata exposed in LAKE AMADEUS and BLOODS RANGE are predominantly Neoproterozoic to Devonian sandstones, which are largely covered by sand dunes, as well as by the extensive Cenozoic playa lake deposits of Lake Amadeus and (Figure 2h; eg Chen et al 1993). The first-order structural pattern of LAKE AMADEUS and BLOODS RANGE is that of doubly-plunging, generally broad to open folds with northwest-striking axial planes. The recently defined Liddle and Puna Kura Kura formations of the Winnall Group (Donnellan and Normington 2017) extend along strike from HENBURY onto LAKE AMADEUS; sandstone of Liddle Formation (formerly mapped as Winnall beds in the western Amadeus Basin) extends across HENBURY, LAKE h AMADEUS and BLOODS RANGE. Unlike HENBURY, strata previously mapped as Inindia beds on LAKE AMADEUS and BLOODS RANGE are not recognisable as a distinct part of the northeastern Amadeus Basin Neoproterozoic succession, due primarily to extensively weathered, small, isolated exposures. In the northeast corner of LAKE AMADEUS, the Mereenie oil and gas field produces from Palaeozoic sandstone of the doubly-plunging Mereenie anticline (eg Jackson 1984, Ambrose 2006). LAKE AMADEUS also includes the excellent exposures of Carmichael Sandstone and overlying Mereenie Sandstone at (Bagas 1988). In addition to the Amadeus Basin stratigraphy described above, BLOODS RANGE also covers a northern part of the Musgrave Province that consists of late Mesoproterozoic i (Stenian) felsic rocks of the Pottoyu Granite Suite (Close et al 2003). These rocks are nonconformably overlain by volcanic and metasedimentary rocks of the Tjauwata Group, which comprise a latest Mesoproterozoic rift succession (Ngaanyatjarra Rift) that is poorly exposed in the southern part of BLOODS RANGE (Close et al 2003, Aitken et al 2013). Major periods of deformation in the Musgrave Province include Stenian rifting (resulting in deposition of the Tjauwata Group) and shortening during the Petermann Orogeny, which produced nappe geometries involving both Musgrave Province and basal Amadeus Basin stratigraphy (Close et al 2013). Periods of contractile deformation during both the Petermann and Alice Springs orogenies produced the fold-and-thrust belt geometry of the Amadeus Basin in the central and northern parts of BLOODS RANGE (Weisheit 2021). Figure 2. (Continued from previous page). Field photographs from the Amadeus Basin. (g) Skolithos and underlying cross- stratification in the Cambro–Ordovician Pacoota Sandstone, Insights from detrital zircon U–Pb geochronology HENBURY. (h) Evaporite deposits and intervening sand islands of Lake Neale, BLOODS RANGE. (i) Ridges of shallowly-dipping As part of the mapping projects described above, a Cambrian Cleland Sandstone, LAKE AMADEUS. considerable amount of detrital zircon U–Pb geochronology

77 AGES 2021 Proceedings, NT Geological Survey data have been collected (Normington et al 2016, 2018, Cambrian in the central Amadeus Basin, Northern 2019a, b; Kositcin et al 2018, in review; Verdel et al 2019, Territory: in ‘Annual Geoscience Exploration Seminar Beyer et al 2020, Verdel and Woodhead in prep). These (AGES) Proceedings, Alice Springs, Northern Territory, data are useful in three ways. First, in some cases, the 28–29 March 2017’. Northern Territory Geological youngest zircons from a stratigraphic unit help to refine Survey, Darwin, 80–85. its depositional age. An example is the Cleland Sandstone Donnellan N and Normington VJ, in prep. Henbury (Figure 2i), part of which contains zircons nearly as Special, Northern Territory (First Edition). 1:100 000 young as the Cambrian–Ordovician boundary (Beyer et al geological map series, 5548 and parts of 5448, 5449 2020, Kositcin et al in review). Second, detrital zircon age and 5549. Northern Territory Geological Survey, distribution varies spatially across the Amadeus Basin (eg Darwin. Verdel 2021), a pattern that reflects differences in provenance, Forman DJ, 1963. Regional geology of the Bloods Range most generally the difference between sediment sources in sheet, south-west Amadeus Basin. Bureau of Mineral the Aileron and Warumpi provinces to the north versus Resources, Australia, Record 47. those in the Musgrave Province to the south. Third, some of Haines PW, Hand M and Sandiford M, 2001. Palaeozoic the new detrital zircon results include zircon geochemistry synorogenic sedimentation in central and northern data (Normington et al 2019b, Beyer et al 2020, Verdel and Australia: a review of distribution and timing with Woodhead in prep). Given that most of the detrital zircons implications for the evolution of intracontinental orogens. in the Amadeus Basin seem to have originally formed in the Australian Journal of Earth Sciences 48, 911– 928. Aileron, Warumpi and Musgrave provinces, geochemical Haines PW, Kirkland CL, Wingate MTD, Allen H, variation of the Amadeus Basin zircons (most notably Hf Belousova EA and Gréau Y, 2016. Tracking sediment isotope composition, as well as trace element composition) dispersal during orogenesis: A zircon age and Hf isotope reflects tectonic and magmatic processes that occurred study from the western Amadeus Basin, Australia. within the crystalline basement regions of Gondwana Research 37, 324–347. (eg Hollis et al 2013, Haines et al 2016, Verdel et al 2021). Hollis JA, Kirkland CL, Spaggiari CV, Tyler IM, Haines PW, Wingate MTD, Belousova EA and References Murphy RC, 2013. Zircon U–Pb–Hf isotope evidence for links between the Warumpi and Aileron Provinces, Aitken ARA, Smithies RH, Dentith MC, Joly A, Evans S west Arunta region. Geological Survey of Western and Howard HM, 2013. 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Joint NTGS–GA geochronology Territory Geological Survey, Record 2018-010. project: western Amadeus Basin, July 2019–June Kositcin N, Verdel C, Normington VJ and Simmons JM, 2020. Northern Territory Geological Survey, Record in review. Summary of results. Joint NTGS–GA 2020‑006. geochronology project: western Amadeus Basin, Chen X-Y, Bowler JM and Magee JW, 1993. Late Cenozoic July– August 2020. Northern Territory Geological stratigraphy and hydrologic history of Lake Amadeus, Survey Record. a central Australian playa. Australian Journal of Earth Menpes S, Walshe P, Bache F, Gusterhuber J and Sciences 40, 1–14. Sheridan M, 2018. Exploring the southern Amadeus Close DF, 2013. Chapter 21 - Musgrave Province: in Basin with 2D seismic: in ‘Annual Geoscience Ahmad M and Munson TJ (editors). ‘Geology and Exploration Seminar (AGES) Proceedings, Alice mineral resources of the Northern Territory.’ Northern Springs, Northern Territory, 20–21 March 2018’. Territory Geological Survey, Special Publication 5. Northern Territory Geological Survey, Darwin, 92–95. Close DF, Edgoose CJ and Scrimgeour IR, 2003. Hull and Morgan-Wall T, 2020. R package version 0.19.2. rayshader: Bloods Range, Northern Territory, 1:100 000 geological Create Maps and Visualize Data in 2D and 3D. https:// map series explanatory notes, 4748, 4848. Northern github.com/tylermorganwall/rayshader Territory Geological Survey, Darwin. Normington VJ, Beyer EE, Whelan JA, Edgoose CJ and Donnellan N, Edgoose CJ and Weisheit A, in prep. Henbury, Woodhead JD, 2019b. Summary of results. NTGS Northern Territory (Second Edition). 1:250 000 LA– ICP–MS Hf program: Amadeus Basin, July geological map series, SG 53-01. Northern Territory 2013– June 2015. Northern Territory Geological Survey, Geological Survey, Darwin. Record 2019-005. Donnellan N and Normington VJ, 2017. Towards a revised Normington VJ and Donnellan N, 2020. 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Amadeus Basin, Northern Territory. Northern Territory Verdel C, Campbell M and Allen C, 2021. Detrital zircon Geological Survey, Record 2020-010. petrochronology of central Australia, and implications Normington VJ, Donnellan N, Orth K, Thompson JM for the secular record of zircon trace element composition. and Meffre S, 2019a. Summary of results. NTGS Geosphere 17. https://doi.org/10.1130/GES02300.1 LA– ICP– MS U–Pb geochronology project: selected Verdel C, Edgoose CJ, Donnellan N and Huang H, samples from HENBURY 1:250 000 mapsheet, 2019. Summary of results. NTGS LA–ICP–MS Amadeus Basin, July 2016–June 2017. Northern U– Pb geochronology project: Detrital zircon U–Pb Territory Geological Survey, Record 2019-004. geochronology of the Parke Siltstone, HENBURY Normington VJ, Donnellan N, Thompson JM and Meffre S, 1:250 000 mapsheet, Amadeus Basin. Northern 2018. Summary of results. NTGS LA–ICP–MS U– Pb Territory Geological Survey, Record 2019-013. geochronology project: selected samples from the Verdel C, Normington V, Donnellan N and Simmons J, central Amadeus Basin, July 2014 – June 2016. Northern 2020. Ediacaran stratigraphic correlations in the Territory Geological Survey, Record 2018-011. western Amadeus Basin, central Australia: in ‘Annual Normington VJ, Edgoose CJ, Donnellan N, Thompson J Geoscience Exploration Seminar (AGES) Proceedings, and Meffre S, 2016. Summary of results NTGS Alice Springs, Northern Territory, 24–25 March 2020’. LA– ICP–MS U–Pb program: Amadeus Basin, July Northern Territory Geological Survey, Darwin, 96–99. 2014–June 2015. Northern Territory Geological Survey, Verdel C, Normington V, Simmons J, and Edgoose CJ, Record 2016-005. in prep. Bloods Range, Northern Territory (Second Raimondo T, Collins AS, Hand M, Walker-Hallam A, Edition). 1:250 000 geological map series, SG 52-03. Smithies RH, Evins PM and Howard HM, 2010. The Northern Territory Geological Survey, Darwin. anatomy of a deep intracontinental orogeny. Tectonics 29. Verdel C, Normington V, Simmons J, and Edgoose CJ, Scrimgeour IR, 2013a. Chapter 12 - Aileron Province: in prep. Lake Amadeus, Northern Territory (Second in Ahmad M and Munson TJ (editors). ‘Geology and Edition). 1:250 000 geological map series, SG 52‑04. mineral resources of the Northern Territory.’ Northern Northern Territory Geological Survey, Darwin. Territory Geological Survey, Special Publication 5. Verdel C and Woodhead J, in prep. Summary of results. Scrimgeour IR, 2013b. Chapter 13 - Warumpi Province: NTGS LA–ICP–MS Hf program: Amadeus Basin, 2015. in Ahmad M and Munson TJ (editors). ‘Geology and Northern Territory Geological Survey, Record. mineral resources of the Northern Territory.’ Northern Weisheit A, 2021. West Amadeus Basin, Northern Territory Territory Geological Survey, Special Publication 5. (First Edition). 1:500 000 interpreted geological map. Verdel C, 2021. Detrital zircon facies of the Amadeus Basin, Northern Territory Geological Survey, Darwin. central Australia. Poster. Australian Earth Sciences Wells AT, Ranford LC and Cook PJ, 1963. The geology Convention, 9–12 February 2021. Geological Society of of the Lake Amadeus 1:250 000 sheet area. Bureau of Australia. Mineral Resources, Australia, Record 51.

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