GEOLOGICAL SURVEY

JN Dunster, PW Haines and TJ Munson and impact structures in the Northern Territory RECORD 2014-007 DEPARTMENT OF MINES AND ENERGY MINISTER: Hon Willem Westra van Holthe MLA CHIEF EXECUTIVE: Scott Perkins

NORTHERN TERRITORY GEOLOGICAL SURVEY EXECUTIVE DIRECTOR: Ian Scrimgeour

JN Dunster, PW Haines and TJ Munson NTGS Record 2014-007. Meteorites and impact structures in the Northern Territory

BIBLIOGRAPHIC REFERENCE: Dunster JN, Haines PW and Munson TJ, 2014. Meteorites and impact structures in the Northern Territory. Northern Territory Geological Survey, Record 2014-007.

(Record / Northern Territory Geological Survey ISSN 1443–1149) Bibliography ISBN (DVD): 978-0-7245-7277-9 ISBN (Web): 978-0-7245-7276-2

Keywords: ataxitic texture, , , , , iron meteorites, kamacite, , Neumann bands, , schreibersite, shatter cones, , stony irons, taenite, , troilite, Widmanstätten pattern, Alikatnima, Amelia Creek, Arltunga, Barramundi, Basedow Range, Bond Springs, Boxhole, Burt Plain, Calvert Hills, Cleanskin, Eagles Nest, Erldunda, Eurowie Creek, Foelsche, Gallipoli Station No. 1, Gallipoli Station No. 2, Glen Helen, Gosses Bluff, Gove, Goyder, Gulpuliyul, Hart Range, Henbury, , Kelly West, Kurinelli , Liverpool, Maningrida, Matt Wilson, Mount Sir Charles, Nutwood Downs, Poeppel Corner, Puka, Rabbit Flat, Renehan, Roper River, Sheridan Creek, Spear Creek, Spring Range, Strangways, Tawallah Valley, Wessel, Yenberrie.

EDITOR: GC MacDonald

Northern Territory Geological Survey 3rd floor Paspalis Centrepoint Building Arid Zone Research Institute Smith Street Mall, Darwin South , GPO Box 4550 PO Box 8760 Darwin NT 0801, Alice Springs NT 0871, Australia

For further information contact: Minerals and Energy InfoCentre Phone: +61 8 8999 6443 Website: http://www.minerals.nt.gov.au/ntgs Email: [email protected]

© Northern Territory Government October 2014

Cover illustration: simulation of meteorite descending to impact NT (Top image: after Google earth, Data SIO, NOAA, US Navy, NHA, GEBCO, Image Landsat 2014. Bottom image: Gosses Bluff, after Google earth, DigitalGlobe, CNES/Astrium 2014).

Disclaimer While all care has been taken to ensure that information contained in this publication is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of its information. The Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice contained in this publication, or that it is suitable for your intended use. You should not rely upon information in this publication for the purpose of making any serious business or investment decisions without obtaining independent and/or professional advice in relation to your particular situation. The Northern Territory of Australia disclaims any liability or responsibility or duty of care towards any person for loss or damage caused by any use of, or reliance on the information contained in this publication.

NTGS Record 2014-007 ii CONTENTS FIGURES

Summary...... v 1. Location of meteorites, impact structures and circular Introduction...... 1 features of unknown affinity in the NT...... 2 History...... 1 2. Amelia Creek impact structure. (a) satelline image. Modern recognition of impact craters...... 1 (b) Aeromagnietic anomaly ...... 4 Meteorites and impact structures of the NT...... 2 3. Geological map of the Amelia Creek impact Known meteorites and impact structures of the NT...... 4 structure...... 5 Alikatnima meteorite (1)...... 4 4. Amelia Creek shatter cones...... 5 Amelia Creek (2)...... 4 5. Boxhole impact crater. (a) Satellite image. (b) Impact Arltunga meteorite (3)...... 6 structure geology map...... 7 Basedow Range meteorite (4)...... 6 6. Boxhole fragment...... 8 Bond Springs meteorite (5)...... 6 7. Cleanskin shatter cones in sandstone...... 9 Boxhole (Dneiper) crater and meteorites (6)...... 6 8. Photomicrograph of multiple planar fractures with Burt Plain meteorite (7)...... 8 feather features in quartz...... 9 Cleanskin impact structure (8)...... 9 9. Cleanskin impact structure. (a) Satellite image. Eagles Nest meteorite (no location)...... 11 (b) Impact structure geology map...... 10 Erldunda meteorite (9)...... 11 10. Foelsche impact crater. (a) Satellite image. Foelsche impact structure (10)...... 11 (b) Circular aeromagnetic anomaly...... 11 Gallipoli Station No. 1 meteorite (no location)...... 12 11. Foelsche impact crater. Shock lamellae in Bukalara Gallipoli Station No.2 meteorite (11)...... 12 Sandstone...... 12 Glen Helen meteorite (12)...... 13 12. Gallipoli Station No.2 meteorite fragments...... 12 Gosses Bluff (Tnorala) impact structure (13)...... 13 13. Gallipoli Station No.2 polished slab...... 13 Gove meteorite (14)...... 16 14. Gallipoli Station No.2. photomicrograph of polished Goyder impact structure (15)...... 17 section...... 13 Hart (or Harts) Range meteorite (16)...... 17 15. Gosses Bluff impact structure. (a) Satellite image. Henbury (Tatjakapara) craters and meteorites (17).....17 (b) Residual gravity map...... 14 Huckitta meteorite (18)...... 21 16. Gosses Bluff impact structure...... 15 Kelly West impact structure (19)...... 22 17. Geological sketch map of Gosses Bluff impact Kurinelli meteorites (20)...... 22 structure...... 15 Liverpool impact crater (21)...... 24 18. Gosses Bluff shatter cones...... 16 Matt Wilson impact structure (22)...... 24 19. Goyder impact structure. (a) Satellite image. Mount Sir Charles meteorite (23)...... 27 (b) Impact structure simplified geology...... 18 Nutwood Downs meteorite (no location)...... 27 20. Henbury impact structures...... 19 Poeppel Corner meteorite (24)...... 28 21. Henbury impact structure. (a) Radiometric anomaly Rabbit Flat meteorite (25)...... 28 for potassium. (b) Satellite image...... 20 Roper River meteorite (26)...... 28 22. Henbury meteorite fragments...... 20 Strangways impact structure (27)...... 28 23. Huckitta meteorite in situ...... 21 Tawallah Valley meteorite (28)...... 28 24. Huckitta meteorite polished samples. (a) Close-up of Yenberrie meteorite (29)...... 30 polished surface. (b) Fragment...... 21 Possible impact structures...... 30 25. Kelly West impact structures. (a) Satellite image. Calvert Hills structure (A)...... 30 (b) Impact structure geology...... 23 Gulpuliyul structure (B)...... 31 26. Kurinelli weathered iron meteorite sample...... 24 Maningrida structure (C)...... 31 27. Liverpool impact crater. (a) Satellite image. Renehan structure (D)...... 31 (b) Impact structure geology...... 25 Wessel structure (E)...... 34 28. Matt Wilson impact structure. (a) Satellite image. Circular structures of unknown affinity...... 34 (b) Impact structure geology...... 26 Barramundi circular structure (I)...... 34 29. Matt Wilson impact structure outcrop photographs Eurowie Creek circular structure (II)...... 34 (a) Closely spaced fractures in Wondoan Hill Formation Puka circular structure (III)...... 35 sandstone. (b) Striated fracture surface...... 27 Sheridan Creek circular structure (IV)...... 36 30. Strangways impact structure. (a) TMI image. Spear Creek circular structure (V)...... 36 (b) Strangways geology...... 29 Spring Range circular structure (VI)...... 36 31. Tawallah Valley meteorite...... 30 Economic implications...... 36 32. Yenberrie iron meteorite sample...... 31 Legal issues regarding meteorites...... 40 33. Calvert Hills structure. (a) Satellite image. Acknowledgements...... 40 (b) Magnetics-radiometric overlay image...... 31 References...... 40 34. Gulpuliyul structure. (a) Satellite image. Appendix 1. List of meteorite and impact structures (b) Geological sketch map...... 32 of the NT...... 45 35. Maningrida structure. (a) Haul Round Island and Appendix 2. System...... 46 submerged outcrop off centre of the Maningrida structure. (b) Magnetic 1VD image...... 33

iii NTGS Record 2014-007 36. Renehan structure. (a–b) Satellite images. (c) Magnetic TABLES 1VD image. (d) East–west magnetic transect...... 33 37. Wessel structure. (a) Satellite image. (b) TMI- 1. Meteorites, impact structures and circular structures radiometric overlay image...... 34 of the NT...... 3 38. Barramundi circular structure. (a) Satellite image. 2. Google earth links (kmz file) for all locations...... 3 (b) TMI image...... 34 39. Eurowie Creek circular structure. (a) Satellite image. (b) Radiometric image...... 35 APPENDIX TABLES 40. Puka circular structure...... 35 41. Sheridan Creek circular structure. (a) Satellite image. A1. List of meteorite and impact structures of the NT.....45 (b) TMI image...... 36 A2. Stony meteorites – ...... 46 42. Spear Creek circular structure. (a) Satellite image. A3. Stony-iron meteorites...... 46 (b) Magnetic profile...... 37 A4. Iron meteorites – structural classification...... 47 43. Spear Creek geology and cross section...... 38 A5. Iron meteorites – chemical classification...... 47 44. Spring Range circular structure...... 39

NTGS Record 2014-007 iv Meteorites and impact structures in the Northern Territory By JN Dunster, PW Haines and TJ Munson

SUMMARY

The Northern Territory (NT) contains some of Earth’s best examples of impact structures and meteorites. At the time of writing, the recognises nine unequivocal impact structures in the NT which represents 35% of their Australian total. The NT also has 23 other well documented and formally recognised meteorites or impact structures, plus an additional 11 possible impact structures or circular structures of unknown affinity, for a total of 43 described in this report. Structural, geochemical and formational evidence can support the recognition of an impact structure. Definitive evidence comes from the recognition of shock metamorphic affects in the target rocks and/or an extra-terrestrial geochemical/isotopic signature associated with . Confirmed impact sites are referred to simply as ‘impact structures’, and the term ‘structure’ is used for those of unconfirmed or uncertain origin. Meteorites and their impact structures have a number of value-related implications. They have scientific value, cultural significance and are important for tourism and education. Moreover, impact cratering is considered as a potential driver of economic mineral formation. Impact structures themselves are viable exploration targets for a range of commodities. Approximately 25% of all terrestrial impact craters world-wide have some resource affiliation, either as a direct result of the or through modification of the target rocks. Impact-related resources can be classified as pro-, syn- or epigenetic, depending on the timing relative to impact. Progenetic examples include the Vredefort Dome in South Africa where the crater has preserved, and possibly enhanced the Witwatersrand gold field. The best known example of a syngenetic impact-related resource is the -dominated mineralisation at Sudbury in Canada. Epigenetic metalliferous deposits commonly invoke fracture porosity and permeability, and hydrothermal convection cells analogous to those above igneous intrusions. The most economically significant epigenetic impact-related resources are hydrocarbons. Impact can enhance or create reservoir porosity and permeability to the extent that even impact-fractured crystalline basement has been exploited as a hydrocarbon reservoir. One example is the Cameche Bay oil fields in the Gulf of Mexico which have been directly linked to the Chicxulub impact structure. Although Australia and the NT have an extensive impact history by world standards, there are no known economic resources unequivocally directly related to impact structures. Many of the NT impact structures are considered too small or too deeply eroded to warrant mineral exploration. Gosses Bluff is the only confirmed impact structure to have knowingly been explored for its resource potential where the crater has been tested by two petroleum wells. Elsewhere, there may be a relationships between base metals mineralisation at the Spear Creek structure and its possible impact origin. Evidence for previously undocumented impact structures is welcomed by NTGS. Any meteorites found in the NT must, by law, be reported to the Museum and Art Gallery of the Northern Territory (MAGNT). All meteorites found in the NT since 1988 remain the property of the Crown and the export of meteorite material is covered by separate Federal legislation. Suspected meteorite falls should be urgently reported in the first instance to the MAGNT with as much detail as possible.

v NTGS Record 2014-007 THIS PAGE LEFT INTENTIONALLY BLANK

NTGS Record 2014-007 vi INTRODUCTION phenomena known as fireballs, and more importantly, that they must have their origins in outer space. The Northern Territory (NT) contains some of Earth’s Chladni didn’t have long to wait for the first best examples of impact structures and meteorites. At the incontrovertible scientific evidence. On December 13 1795, time of writing, the Meteoritical Society recognises nine a stone of about 25 kg was seen to fall at Wold Cottage, unequivocal impact structures in the NT which represents England, by several eyewitnesses. The fall occurred in 35% of their Australian total. The NT also has 23 other broad daylight, out of a clear sky, refuting the then most documented and formally recognised meteorites or impact popular explanations for the formation of meteorites, such structures plus an additional 11 examples for a total of 43 as lightning or condensation in clouds. Subsequently, the described in this report (Table 1). The impact structures was analysed by a British chemist, and meteorite locations are shown in Figure 1. Edward Howard, who found it to contain nickel-iron metal, The original intention of early versions of this document similar in composition to the iron meteorites described in was to supersede a pamphlet previously available from the Chladni’s book. In 1802, Howard published the results of Department of Mines in Alice Springs (1991). This more his analysis and his conclusions regarding the Wold Cottage expansive NT-wide version follows an unpublished work incident, convincing a growing number of scientists that for the Northern Territory Geological Survey (NTGS) by meteorites actually represent extra-terrestrial matter falling Haines (2004). It also draws on published work by Haines from the sky. The Wold Cottage meteorite became iconic, (2005), data from the Meteoritical Society (International to the extent that many museums, including the Museum of Society for and Planetary Science) database, the Victoria, display replicas. maintained by Planetary and Space The scientific study of meteorites became popular again Science Centre, University of New Brunswick (PSSC) and during the Victorian period when the study of “Natural other key references, as acknowledged below. This record History” was a common past time. Many specimens documents additional confirmed impact structures and were collected by amateurs and scientific expeditions briefly describes some possible candidates. from around the world, including in the NT. Advances in This is the first attempt at publishing a NT compilation, analytical chemistry during the middle of the 19th century but undoubtedly other NT meteorites remain undocumented and the invention of the petrographic microscope, led to in private and museum collections, and other potential a complex classification system Appendix( 2) that is still impact structures have been recognised, but not published used today. in the scientific literature. Evidence of previously undocumented impact structures are welcomed by NTGS. MODERN RECOGNITION OF IMPACT CRATERS Any meteorites found in the NT must, by law, be reported to the Museum and Art Gallery of the Northern Territory It took more than a hundred years after the Wold Cottage (MAGNT; see the concluding section). The location of fall for ancient terrestrial impact craters to be recognised meteorite finds should be photographed with an appropriate as such by the scientific community. Werner (1904) was the scale, accurately recorded with GPS coordinates and first scientist to propose an impact origin for a terrestrial preferably left undisturbed for authorities to investigate. crater (Ries structure in Germany), but definitive evidence As explained in the final section, all meteorites found in was not documented until the early 1960s. Barringer the NT since 1988 remain the property of the Crown and (1906) proposed an impact origin for the crater in Arizona, export of meteorite material is covered by separate Federal USA, which now bears his name, but it was not formally legislation. Suspected meteorite falls should be urgently recognised as an impact crater by the reported in the first instance to the MAGNT with as much Geological Survey until 40 years later. Dietz (1947) first detail as possible. proposed that shatter cones could be used as an indicator of impact-induced shock. McIntyre (1962) and Carter HISTORY (1965) added micro-shock microstructures such as planar deformation features in quartz. High pressure minerals, Meteorites have always been part of history and religion such as and , high density polymorphs of and their arrival has been recorded in almost every culture. quartz, were recognised later. Meteorite fragments have been venerated as sacred objects, Older impact structures may be deeply eroded or buried used for tools or for decorative purposes, or exploited as and are not expected to preserve unaltered meteorite a source of iron, at least since the Iron Age. Burke (1986) debris or display a full suite of diagnostic features. These provided an overview and Hamacher and Norris (2009) are more difficult to recognise and the initial discovery of discussed the Australian Aboriginal geomythology with such structures usually follows investigations of anomalous several NT examples. circular features either exposed at the surface and/or The scientific acceptance of an extra-terrestrial origin revealed in the subsurface by interpretation of geophysical for meteorites began in the late 1700s and is documented data. by Fectay and Bidaut (2014). In 1794, a German physicist, Structural, geochemical and formational evidence can Ernst Florens Chladni, published a paper called ‘On also support the recognition of an impact structure. Three- the Origin of the Pallas Iron and Other Similar to it, and dimensional structural relationships can provide strong on Some Associated Natural Phenomena’, in which he grounds for interpreting an impact origin. In addition, compiled all available data on several meteorite finds and impact structures may be associated with projectile- falls. He concluded that meteorites were responsible for the derived geochemical anomalies in impact melts, ,

1 NTGS Record 2014-007 injected melt veins or ejecta layers. Definitive evidence ‘structure’ is used for those of unconfirmed or uncertain comes from the recognition of shock metamorphic affects origin. in the target rocks and/or an extra-terrestrial geochemical/ isotopic signature associated with impactites (Haines METEORITES AND IMPACT STRUCTURES OF 2005). McCall (2009) provided a review of the history and THE NT progress in interpreting impact structures during the past fifty years. There are 32 recorded meteorite or impact structures in Impact craters are classified as either ‘simple’ the NT, plus 5 possible impact structures and a further 6 craters, which have a circular bowl-shaped topography, circular structures of unknown affinity. All 43 are listed or ‘complex’ craters that display a variety of late-stage in Table 1 with their approximate locations shown on modifications that typically include a rebounded central Figure 1. Appendix 1 contains a more complete listing uplift and collapsed rim. Large complex craters may have that includes discovery dates, time of impact, weights and a concentric multi-ringed topographic and structural impact evidence. Descriptions of all the occurrences are morphology (Haines 2005). This descriptive classification described in the following sections, in alphabetical order. for craters is used here. Eroded confirmed impact sites The number after each name refers to the map location if are herein referred to simply as ‘impact structures’; known.

Figure 1. Location of meteorites, impact structures and circular features of unknown affinity in the NT. Yellow circle = impact structure or meteorite. White circle = possible impact structure. Blue circle = circular structure of unknown affinity (after Google earth, Data SIO, NOAA, US Navy, NHA, GEBCO, Image Landsat, Digital Globe, CNES/Spot Image 2014).

NTGS Record 2014-007 2 Name Map location ref # Location Officially recognised meteorite Meteorite type* Known meteorite and impact structures Alikatnima meteorite 1 23°20’S 134°07’E  Iron-ung Amelia Creek impact structure 2 20°50’06”S 134°53’01”E – na Arltunga meteorite 3 23°28’S 134°40’E  IID-an Basedow Range meteorite 4 25°06’S 132°33’E – IIIAB Bond Springs meteorite 5 23°30’S 133° 50’E  H6 Boxhole crater and meteorites 6 22°36’46’’S 135°11’43’’E  IIIAB Burt Plain meteorite 7 23°33’S 133°52’E – na Cleanskin impact structure 8 18°09’15”S 137°56’21”E – na Eagles Nest meteorite not recorded ? Erldunda meteorite 9 25°17’47.3”S 133°12’00.2”E  H5 Foelsche impact structure 10 16°39’57”S 136°46’59”E – na Gallipoli Station No. 1 meteorite not recorded ?IIIAB Gallipoli Station No. 2 meteorite 11 18°58’22”S 137°30’20”E  IVB Glen Helen meteorite 12 23°41’S 132°40’E – Iron Gosses Bluff impact structure 13 23°49’07”S 132°18’26”E – na Gove meteorite 14 12°10’48”S 136°46’12”E – Na Goyder impact structure 15 13°28’30”S 135°02’30”E – na Hart Range meteorite 16 23°S 131°E – ?III Henbury craters and meteorites 17 24°34’20”S 133°08’54”E  IIIAB Huckitta meteorite 18 22°17’14.5’S 135 °45’16.3”E  Pallasite-Main gr Kelly West impact structure 19 19°55’46”S 133°57’05”E – na Kurinelli meteorites 20 20°37’S 135°03’E – Liverpool impact crater 21 12°23’46”S 134°02’50”E – na Matt Wilson impact structure 22 15°29’36”S 131°11’23”E – na Mount Sir Charles meteorite 23 23°50’S 134°02’E  IVA Nutwood Downs meteorite not recorded – IIIAB Poeppel Corner meteorite 24 25°47’S 137°56’E  L6 Rabbit Flat meteorite 25 20°22’S 130°07’E  H6 Roper River meteorite 26 ? 15°S 135°E  IIIAB Strangways impact structure 27 15°12’S 133°34’E – na Tawallah Valley meteorite 28 15°42’S 135°40’E  IVB Yenberrie meteorite 29 14°15’S 132°01’E  IAB-MG Possible impact structures Calvert Hills structure A 17°22’S 137°28’E – na Gulpuliyul structure B 13°19’S 134 °06’E – na Maningrida structure C 11°53’27S 134°12’44E – na Renehan structure D 18°18’45”S 132°39’55”E – na Wessel structure E 20°36’S 135°05’E – na Circular structures of unknown affinity Barramundi structure I 16°49’ S 136°40’ E – na Eurowie Creek structure II 22° 27’ S 136° 04’ E – na Puka structure III 24°03’05.33”S 132°42’33.75” – na Sheridan Creek structure IV 13°04’10”S 135°06’01”E – na Spear Creek structure V 17°16’37.5”S 135°50’03”E – na Spring Range structure VI 21°51’43”S 134°18’28” E – na na = not applicable. * see Appendix 2. Table 1. Meteorites, impact structures and circular structures of the NT.

NTGS_Rec2014-007_Table_1_Locations.kmz A Google earth ‘kmz’ file has been provided in the accompanying folder with this Record. Double clicking on the kmz file name will open Google earth (if installed on your computer) and display the geographic locations listed in Table 1. Table 2. Google earth links (kmz file) for all locations.

3 NTGS Record 2014-007 KNOWN METEORITES AND IMPACT most references citing 20 x 12 km. Certainly 16 km appears STRUCTURES OF THE NT acceptable as an average diameter. The structure is not readily discernible with the existing gravity coverage, but This section lists the known meteorites and impact a positive magnetic anomaly of 100 nT in the centre of the structures in the NT in alphabetical order. The number after structure is possible related to the impact (Figure 2b). The each name refers to the map location (Figure 1) if known. first suspicions that the site may be an impact feature were raised when conical jointing was observed during regional Alikatnima meteorite (1) geological mapping in 1981. Macdonald and Mitchell visited the area in 2002 and 2003, and identified shock-induced The Alikatnima meteorite was found in 1931 at 23°20’S shatter cones with upward-directed apices (Macdonald et al 134°07’E 47 km northeast of Alice Springs and was reported 2005, Figure 3). to have weighed 20 kg, but there is some uncertainty as to Shatter-cones (Figure 4) up to a metre high cover at both the location and mass. The discovery is attributed to least 6 km2 and, after Gosses Bluff, Amelia Creek is one of Mr B Webb of Alice Springs, who sold it to Mr FS Jones the most prolific shatter-cone localities in Australia. Cones of Highgate, who then sold two samples totalling 15.9 kg are ubiquitous in the Unimbra Sandstone and also occur in to the South Australian Museum. It is not recorded what felsic volcanic rocks and in the Yeeradgi Sandstone. All happened to the remaining ca 4 kg other than that it was of these formations are part of the Wauchope Subgroup retained in Alice Springs. Two pieces of 9.1 kg and 6.8 kg of the Palaeoproterozoic Hatches Creek Group, which (totalling the 15.9 kg) are still in the South Australian was tectonically deformed prior to impact. Feather-like Museum and a polished slab is held by the Smithsonian microstructures, possibly incipient planar deformation National Museum of Natural History. The Australian features stemming at an angle from planar fractures, are National University has 31 g. The Alikatnima meteorite is present in quartz grains of the target sandstone. These described as an Ni-rich Iron IRANOM type and microstructures are distinct from tectonic fractures and was reported to contain 13.8% Ni, 0.28% Ga, 0.14ppm Ge, are typical of those observed in quartz grains at other 4.2 ppm Ir (Graham et al 1985, Meteoritical Society 2009). probable impact structures, and have been reproduced Small crystals of daubréelite and schreibersite are present. in the laboratory by shock experiments (Poelchau The meteorite lacks a fusion crust as such, but a 2 cm thick and Kenkmann 2011). Large autogenic breccias are heat-affected zone is present (Fitzgerald 1979). No other developed along fault lines and clastic dikes are present. detailed published information is available. The asymmetry of the overall structure may indicate an oblique impact. Amelia Creek (2) There is no presently discernible central structural uplift and no melt or allogenic breccia has been Amelia Creek impact structure is an asymmetrical structural observed, implying at least a moderate level of erosion. An disturbance (Figure 2) centred at 20°50’06”S 134°53’01”E age of 1640 –600 Ma has been inferred, with the younger age in the Davenport Ranges of the NT. The key reference is determined from unconformably overlying Neoproterozoic Macdonald et al (2005). The structure is deeply eroded, rocks. Amelia Creek has been likened to the enigmatic Wessel and the original rim diameter is open to interpretation, with structure 30 km away (Macdonald and Mitchell 2004).

a b

Figure 2. Amelia Creek impact structure; red outline indicates approximate area of pervasive shatter-coning. (a) Satellite image (after Google earth, Digital Globe, CNES/Spot Image 2014). (b) Aeromagnetic anomaly (after NTGS GIWS 2014).

NTGS Record 2014-007 4 134°50'0"E 134°55'0"E 20°45'0"S

73 70

85 85

65

65

65 75 55 75 85 70 60 60 70 80 88 20°50'0"S 55 70 80 86 80 82 67 87 0 76 75 52 84 60 60 80 60 65 30 60 75 65 80 60 65 75 85

50 60 55

60 80 75 20°55'0"S

0 31.5 6 km

pervasive shatter-coning Palaeoproterozoic Cenozoic Gum Ridge Fm dolerite alluvium Neoproterozoic Hanlon Subgroup Hatches Creek Group laterite Andagera Fm Wauchope Subgroup conglomerate breccia Ooradidgee Group attitude fault anticline drainage syncline extent of magnetic anomaly A14-169.ai Figure 3. Geological map of the Amelia Creek impact structure (Macdonald et al 2005).

Figure 4. Amelia Creek shatter cones (Macdonald et al 2005).

5 NTGS Record 2014-007 Arltunga meteorite (3) Wells along the south side of Basedow Range some time prior to 1957. The discovery site is about 85 km southwest The Arltunga meteorite has apparently not been described of the Henbury Craters. The mass was described as ‘a few more recently than Mawson (1934), Edwards (1943) and kilograms’, of which 1.24 kg and 858 g samples are in the Axon (1968). The following is based on their work. The Australian Museum, and the Smithsonian holds 246 g. It meteorite was found almost completely buried in soil is an iron type IIIA. Fitzgerald (1979) also described it as by Daniel Pedler in late 1908, and was reported to the a medium octahedrite having a Widmanstätten pattern South Australian Mines Department (NT was at the time with long straight kamacite lamellae and Neumann bands. administered from South Australia). The Government Schreibersite occurs only as rare veinlets. Sporadic Geologist, HYL Brown, referred the discoverer to the South elongated nodules of troilite are accompanied by abundant Australian Museum, with the result that the meteorite was plates of carlsbergite. Fitzgerald (1979) followed earlier purchased by that institution in November of the same year. workers in ascribing the Basedow Range meteorite to the The find was located 3.2 km south of the then Government Henbury shower and postulating anthropogenic transport. Cyanide Works at Arltunga, a mining centre in the eastern MacDonnell Ranges (23°28’S 134°40’E). The iron mass Bond Springs meteorite (5) was reported to have cut its way obliquely into the ground to a depth of about 1.5 m, excavating a groove, at one end of The 6.18 g Bond Springs meteorite was found on the which it was seen to be embedded with only a small corner surface 22 km north of Alice Springs near the Overland projecting from the soil. The actual fall was not witnessed, Telegraph Line at approximately 23°30’S 133°50’E. This but it apparently occurred only a short time before its is near the present Stuart Highway, and is 6 km from discovery - certainly not more than several years, and the Burt Plain and 16 km from the Mount Sir Charles probably considerably less, because the groove scored in the meteorite finds, respectively. The date of the Bond Springs ground would have become obliterated by wind-blown sand find is generally regarded as 1898, being the date cited and wash (Fitzgerald 1979). If this interpretation is correct, when it was donated to the University of Melbourne by the fall probably occurred around 1907–1908. However, Mr FH McK Grant in 1931. However, Fitzgerald (1979) Buchwald (1975) suggested that this was unlikely given the pointed out that it was also stated that it was found while apparent extent of weathering of the meteorite. Oodnadatta was a railway terminus. This puts the date of The original meteorite weighed 18.1 kg and had a the find between 1891 and early 1898. The meteorite was solid squat polygonal shape with a flat base 26 cm by examined by Edwards in the 1940s (Baker and Edwards 16 cm, with an irregular tapering form and a blunt ridge 1941) and was also described by Fitzgerald (1979) as 14 cm above the base. The surfaces were described having a smooth outer skin, free of significant depressions, as generally smooth, there being no definite pits, only the crust being dark brown and less than 0.25 mm thick. broad, shallow depressions and convexities, interpreted It displays numerous chronrules of and pyroxene as ablation features. The specific gravity of unoxidised that are commonly rimmed by nickel-iron and troilite meteorite material was ascertained to be 7.848, and an grains. The latter minerals are also scattered throughout analysis made by the Mines Department indicated 88.06% the matrix. The Bond Springs meteorite is classified as a Fe, 10 –22% Ni, 1.01% Co, 0.26% Cr and 0.24% P. The type H6 chondrite with a density of 3.53 g/ cm3 (Fitzgerald minerals daubréelite, schreibersite and plessite were 1979, Meteoritical Society 2009). A two-gram specimen identified in polished plates. The ataxitic texture consists is held in either the Museum of Victoria or the Geology of a dense grid of kamacite plates aligned octahedrally in a Department of the University of Melbourne (Fitzgerald matrix of plessite (Fitzgerald 1979). Although the chemical 1979), but the location of the remaining main mass is composition falls in the usual range for , unknown. The Bond Springs meteorite has not been no Widmanstätten pattern is visible to the naked eye, studied in detail. however an octahedral arrangement of taenite is visible microscopically. The meteorite has been classified as an Boxhole (Dneiper) crater and meteorites (6) Iron type IID. In addition to the main mass in the South Australian The Boxhole (also called Box Hole or Dneiper)) crater Museum, a 42.2 g specimen of the Arltunga meteorite is is a simple, nearly circular bowl-shaped crater, 180 m in held by the Museum of Victoria, and the Smithsonian diameter at the rim crest and 12 m deep, which is located at National Museum of Natural History (Smithsonian) also 22°36’46’’S 135°11’43’’E, 170 km northeast of Alice Springs has several samples. A 19.6 g sample is held in the Chicago (Figure 5). The name was derived from nearby Boxhole Field Museum, having been acquired through the purchase Station, although the name of this station has subsequently of a private collection. A 49 g meteorite sample in the been changed to Dneiper. This site is not related to the base has been attributed to this meteorite, but metals prospect of the same name, which is actually near Spencer (1932) was describing another specimen, herein the Huckitta impact site. The Boxhole crater and meteorite referred to as Burt Plain. fragments were discovered in the late 1930s by Mr Joseph Webb, an employee on the and a relative of the Basedow Range meteorite (4) owners. The site was first scientifically documented by Madigan The poorly documented Basedow Range meteorite was (1937, 1940) and Mr Bedford of the Kyancutta Museum who reportedly found at 25°06’S 132°33’E, 6.4 km from Wilbia recovered at least 150 kg of meteoritic material (Fitzgerald

NTGS Record 2014-007 6 a

135°11'45"E 135°11'48"E135°11'51"E b 0 100 km

Stuart Highway

Box Hole

Plenty Highway 75 80 70 22°36'42"S 55 70 ALICE SPRINGS 75

75 75

75

60 40 70 80 70 70

70 75

45 22°36'45"S 80 85

70

80 70 80 85 50 fault rim 40 bedding with dip

22°36'48"S bedding, dip unknown 40 foliation with dip vertical bedding vertical foliation

Figure 5. Boxhole impact 135°11'45"E135°11'48"E135°11'51"E crater. (a) Satellite image (after playa schist ejecta gneiss 0 80 m Google earth, CNES/Astrium gravel pre-impact sand schist alluvium and 2014). (b) Impact crater pre-impact colluvium brown schist geological map (Shoemaker reworked ejecta gneiss ejecta quartz et al 2005). A09-189.ai

7 NTGS Record 2014-007 1979). Madigan (1940) also found meteorites about 140 m almost all found where the is absent, notably east of the crater. In 1949, the South Australian Museum on the northern crater rim and on a ridge farther north. Only acquired a single mass of 167 kg from the Webb brothers two fragments were found resting on ejecta. The overall of Mount Riddock Station. During the mid-1950s, the distribution of these fragments is best explained by a shower palaeontologist AA Öpik located widespread meteoritic of meteorites produced by aerodynamic fragmentation of iron while collecting fossils in the general area. He collected the main body. Buchwald (1975) showed that at least some material 400 m north of the then Boxhole . fragments were detached from the main body prior to impact Over the following decades, specimens were intensively and were not part of the main cratering event. Shoemaker collected from the vicinity of the crater until it was declared et al (2005) quoted a 10Be-26Al exposure age of 30 ka from a a protected area. Some of the best material is in private resistant quartz vein in the crater wall and from a resistant collections. However, at least 280 kg are held in museum quartz block in the ejecta. These authors argued against the collections around the world. The Museum of Victoria has previous suggestion by Milton (1972) that the Boxhole and specimens, as does the Smithsonian National Museum for Henbury craters, 300 km apart, might be contemporaneous. Natural History, the British Natural History Museum and the Chicago Field Museum. The South Australian Museum holds Burt Plain meteorite (7) a total of 178 kg and the National Museum of Natural History in Washington has a 3.7 kg piece (Graham et al 1985). Spencer (1932) described an unnamed pallasite meteorite A meteorite found nearby and previously called the Hart collected north of Alice Springs which is herein referred to Range meteorite is now regarded as being synonymous as the Burt Plain meteorite. It was collected by Dr Hebert with Boxhole (de Laeter 1973, Fitzgerald 1979). The key Basedow while leading a Vice Regal Expedition to Central references for Boxhole are Cassidy (1968), Simmons (1974), Australia in 1924. It remained in storage until it was presented Bevan (1996) and Shoemaker et al (1988, 2005). Shoemaker to the British Museum in November 1931. Basedow gave et al (2005) authors mapped the crater. Both Arunta Region the locality as on the Burt Plains (23°33’S 133°52’E). This metamorphic bedrock and pre-crater surficial is immediately north of the MacDonnell Ranges and about deposits have been uplifted and deformed in the walls of the 16 km north of Alice Springs. The fragment was found only crater. The southern rim displays an inverted stratigraphic partly buried in loose ferruginous sand. Basedow believed succession. Ejecta can be traced for more than 300 m south that other pieces of this meteorite remain to be found in the of the crater and there is a well preserved ejecta apron district. comprising fragments of schist and gneiss in the south only. The specimen is an irregular slabby piece measuring Outside the rim, the ejecta blanket is commonly reworked about 11 x 8 x 3 cm and, as received by the museum, and overlapped by a veneer of post-impact alluvium. weighed 1084.5 g. Facing and polishing of one surface Asymmetries of the crater rim and ejecta could be the product reduced the weight to 1036 g. That surface shows hackly of oblique impact from the north or alternatively a function of metal and some flat cleavage planes up to 1 cm across of pre-existing topography. brown olivine, with only a small amount of iron rust. The Intensely deformed and twisted iron meteorite fragments polished surface shows an irregular distribution of nickel- (Figure 6) are typed as a IIIAB medium octahedrite iron and friable olivine. Brecciated fragments of olivine, containing 7.64% Ni, 18.1 ppm Ga, 37.2 ppm Ge and 8.2 ppm often of minute size, are seen scattered through the iron. Ir (Wasson and Kimberlin 1967). Kamacite has a band width A series of linear measurements with a millimetre scale of 1.00 ± 0.15 mm and shock-hardened ε-kamacite is present. gave a mean result of nickel-iron 42 % and olivine 58% (by The Widmanstätten pattern is bent and torn in many of the volume). The polished surface also shows small irregular fragments. Kamacite has been transformed to unequilibrated patches of pale bronze-coloured troilite, which are, in most

α2-kamacite and inclusions of schreibersite and troilite were cases, situated at the junction of the metal and the olivine, commonly melted (Bevan 1996). Collectively, these features but sometimes occurs as small veins in the kamacite. are interpreted as evidence of shock-loading in excess of Grains of kamacite up to 0.5 cm across are surrounded 13 Gpa before impact and that the residual temperature of the by smaller angular areas of plessite, and between these are deformed slugs must have been briefly above 1000°C. bright narrow bands of taenite. Small angular fragments The initial meteorite distribution was deduced by of olivine are embedded in the kamacite, suggesting Shoemaker et al (1988) from oxidised fragments and “iron that the olivine had been broken up before the kamacite shale-balls” overlooked by collectors. Such fragments were crystallised. The granular texture of the metal also suggests that the kamacite was broken up before the separation of the taenite and plessite, and that the fragments had been partly redissolved in the residual melt, giving the reaction- rim of taenite. Finally, the plessite eutectic separated out in the matrix. Microscopically, the kamacite shows well-marked in several directions. Kamacite and taenite show a sharp line of separation, and the Neumann lines do not extend into the taenite. These Neumann lines were possibly developed at the time the kamacite was broken Figure 6. Boxhole iron meteorite fragment (courtesy of up. The plessite shows very fine Widmanstätten patterns, D Edwards, Meteoritical Bulletin). and its feathery edges extend into the taenite, there being

NTGS Record 2014-007 8 no sharp line of demarcation between the two. The bulk sandstones 3.5 km from the centre. These are accompanied chemical composition was given as 55.35% Fe, 4.36% Ni, by bands of brecciated sandstone and siltstone tens of

0.12% Co, 0.13% S, 15.02% SiO2, 6.8% FeO, 17.69% MgO metres in extent. and 0.51% CaO. Melt rocks are not recognised. Most sandstone is The Burt Plain meteorite has also been informally strongly indurated and has a “quartzite” appearance. Thin referred to as the Alice Springs Pallasite in Madigan sections (Figure 8) reveal probable low-level shock effects and Alderman (1939) and Fitzgerald (1979). It has also in quartz grains – multiple planar fracturing, many showing possibly been confused with the Arltunga or Bond Springs feather features, grain mosaicism, and possible planar meteorites. However, at least the former discovery is clearly deformation features. Shatter cones and associated probable separate and the other meteorites are clearly chemically petrographic shock effects indicate that the site is an impact dissimilar. Fitzgerald (1979) and others have suggested structure, but the relatively low levels of shock and structural that the Burt Plain meteorite may be related to the Huckitta relationships suggests it is deeply eroded. Because 1 km to meteorite, despite the separation of over 160 km, given that 3 km of South Nicholson Group is estimated to have existed both are relatively uncommon . above the preserved levels, it is likely that the original crater formed in the uppermost South Nicholson Group, implying Cleanskin impact structure (8) an original crater approximately 20 km in diameter. The Cleanskin Structure lies in rocks estimated to have The Cleanskin impact structure is a 15 km wide area of been deposited between 1400 and 1500 million years ago. deformed rocks (Figures7–9) straddling the Queensland They have not been dated directly, but the age is deduced border centred at 18°09”15”S 137°56’21”E. The deformation from correlation with the radiometrically dated Roper area is inferred to be circular, but is partly concealed beneath Group to the northwest. The South Nicholson Group is undeformed Cretaceous cover. It was recognised by Ian overlain unconformably by early Cambrian rocks about Sweet as an area of unusual structural deformation during 100 km to the west and south, and by Early Cretaceous compilation of the second edition MOUNT DRUMMOND1 rocks throughout the area of interest. geological map. He and Ken Mitchell later identified the The impact clearly occurred before the Cretaceous, as circular nature of the deformation using satellite imagery. these undeformed sedimentary layers blanket the structure. Ken Mitchell visited the area in 2007 and found shatter No contact with Cambrian sedimentary rocks is exposed cones, while Peter Haines identified planar fractures, near the structure. However, impact is believed to have feather features and possible planar deformation features in taken place well before the Cambrian, because the Cambrian thin sections of sandstone that Mitchell collected. rocks lie on the South Nicholson Group at approximately The following summary is taken from an abstract the same erosion level as the present day surface, indicating presented at the 2008 Australian Earth Science Convention that the impact site must have been deeply eroded prior to (Haines et al 2008). The structure lies wholly within Cambrian deposition. the Constance Sandstone, in the lower part of the early Timing of impact could be more tightly constrained Mesoproterozoic South Nicholson Group. The inner if it could be shown that it occurred before the regional several kilometres form a structural dome with at least deformation event that resulted in broad open folding, faulting three repetitions of the same two members of Constance and warping of the South Nicholson Group. However, such Sandstone separated by reverse (thrust?) faults. These faults evidence is lacking at the present time. On the contrary, the are circumferential in pattern, and are unrelated to the east circularity of the structure, and the lack of regional faults - northeast and west - northwest faults associated with intersecting, and displacing, central parts of the structure, regional deformation. Shatter cones (Figure 7) occur in suggests that the impact most probably postdated regional deformation, but predated widespread uplift and erosion. 1 Names of 1:250 000 and 1:100 000 mapsheets are shown in large Therefore, the impact is most likely to have occurred between and small capital letters respectively, eg MOUNT DRUMMOND, about 1400 Ma and the early Cambrian. BENMARA.

Figure 7. Cleanskin shatter cones in sandstone (Haines et al Figure 8. Photomicrograph of multiple planar fractures with 2012). feather features in quartz (Haines et al 2012).

9 NTGS Record 2014-007 a

b

138°E Benmara Doomadgee Nicholson R. Burketown 18°S Cretaceous and younger rocks Bowthorn mudstone-dominated members Lawn Hill

Leichhardt R. Sth Nicholson R. Lawn Hill Ck quartz sandstone-dominated

Mesoproterozoic Constance Sandstone members 0 150 km fault, high angle

Queensland

NorthernTerritory probable thrust fault, Camooweal 20°S geometry unknown

40 dip and strike of strata breccia NT QLD Mount Isa impact structure

20 25 locality microscopic deformation features circular structure (Google earth) circular structure (NASA World Wind) major watercourse

65

05 km A09-186.ai

Figure 9. Cleanskin impact structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) Impact structure geology map (Sweet et al 2008).

NTGS Record 2014-007 10 Eagles Nest meteorite (no location) Geological Survey of Canada and at least some of the material is believed to be in a private collection. No other A stone of 154 g was found by a prospector “next to an information is available. eagle’s nest” in in 1960. It is an oriented meteorite with a complete fusion crust. Although there are Foelsche impact structure (10) mineralogical differences it is possible that it is another stone of the brachina-type meteorite, which was found at The Foelsche impact structure is situated at 16°39’57”S Brachina in South Australia in 1974 (olivine 136°46’59”E in the McArthur Basin, and was described by brachinite: Astronomical Research Network 2006). The Haines and Rawlings (2002). It was specifically targeted mineral composition of the is olivine and serially photographed by the NASA International Space (80%), plagioclase (10%), clinopyroxene (5.5%), iron-sulfide Station on 20 February 2009 (SpaceRef Interactive Inc 2009). (3%), chromite (0.5%), chlorapatite (0.5%), pentlandite The mapped structure (Figure 10a) coincides with a (0.3%) and traces of . prominent circular aeromagnetic anomaly (Figure 10b), which Haines and Rawlings (2002) postulated might be due Erldunda meteorite (9) to removal or displacement of a regional mafic igneous body. The Foelsche Structure is commonly cited as an example Four fragments of the Erldunda meteorite, weighing 190 g of how geophysical techniques can be used to detect eroded total, were found in 1992 at 25°17’47.3”S 133°12’00.2”E and buried impact structures (Haines 2007), or to type about 80 km north-northwest of Alice Springs (Wlotzka their geophysical signature (Hawke 2003). The surface

1994). It is an (H5) with olivine Fa19.6, structure comprises a roughly circular outcrop of flat-lying weathering grade W5. Some material may be held by the Neoproterozoic Bukalara Sandstone, overlying and partly

a

b

Figure 10. Foelsche impact structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/ Spot Image 2014). (b) Circular aeromagnetic anomaly (after NTGS GIWS 2014).

11 NTGS Record 2014-007 rimmed by tangentially striking, steeply dipping, fractured et al (2000). However, Moore in Hutchison et al (1977) and brecciated Mesoproterozoic Limmen Sandstone. The disagreed, based on differing nickel contents. The Henbury latter is interpreted as a relic of the original crater rim about and Gallipoli Station No.1 meteorite sites are >750 km 5 km to 6 km in diameter. A megabreccia on the northwest apart. The following discussion may indicate that Gallipoli crater margin contains angular blocks of sandstone up to Station No. 1 is a valid find and that it may be part of a the size of a house. Further inward, the megabreccia is separate shower to Henbury. onlapped by gently dipping conglomeratic lower Bukalara Sandstone. Gallipoli Station No.2 meteorite (11) Collectively, the geological and geophysical evidence are consistent with a partly buried impact crater, about In September 2001, an iron meteorite which was also 6 km in diameter, with an obscured central uplift estimated informally called Gallipoli (herein Gallipoli Station to be about 2 km in diameter. Locally derived, lithic pebbly No.2) was found by fencer Tom Cusack and grader driver sandstone from the stratigraphically lowest exposed levels Dave Westaway on the boundary fence between Mount of the Bukalara Sandstone on the northeastern side of the Drummond and Gallipoli Stations on the blacksoil plains structure was microscopically examined by Haines and of the (18°58’22”S 137°30’20”E). After Rawlings (2002). Detrital quartz grains display mosaicism, recovery, the meteorite was taken to Mittiebah Station planar fractures and planar deformation features in multiple where it was shown to David Rawlings (then NTGS) and intersecting sets, consistent with impact-induced shock Ian Sweet (ex Australian Geological Survey Organisation), metamorphism (Figure 11). Some grains may have been who removed a small sample (ca 100 g) by hacksaw that subject to shock pressures of up to 20 GPa. was sent to Peter Haines at the University of Tasmania The age of the Foelsche impact structure is bracketed for identification and chemical analysis. The images in by the deposition of the Limmen Sandstone (1492 ± 4 Ma Figure 12 were taken by Rawlings at the station at that time. tuff age from an overlying formation) and the deposition No work on the Gallipoli Station No. 2 meteorite has of the Bukalara Sandstone, and is therefore either been published and the following is based entirely on Mesoproterozoic or Neoproterozoic. Haines and Rawlings unpublished departmental records and correspondence (2002) argued that a Neoproterozoic age is most likely provided by Tim Munson, with input from the other co- because rim preservation suggests rapid burial by the authors. The morphology of the meteorite was briefly Bukalara Sandstone soon after impact. a

Figure 11. Foelsche impact crater. Photomicrograph of Bukalara b Sandstone showing shock lamellae in ?feldspar (NTGS thin section C74051).

Gallipoli Station No. 1 meteorite (no location)

Fitzgerald (1979) referred to a 6 kg medium octahedrite meteorite called Gallipoli (herein Gallipoli Station No. 1), reputedly collected from the pastoral station of the same name in 1970. Its exact discovery location is not recorded and the station owner at that time denied any knowledge of the find. The meteorite was acquired by Mr David New, a New York mineral dealer, from a Surfers Paradise mineral dealer (Fitzgerald 1979) and its present whereabouts is unknown. It was described as a type IIIA. Buchwald (1975) and Fitzgerald (1979) believed it to be part of the Henbury fall, possibly with anthropogenic transport. This Figure 12. Gallipoli Station No.2 meteorite fragment (photographs synonymisation with Henbury was acknowledged by Grady by D Rawlings, 2001).

NTGS Record 2014-007 12 described by David Rawlings as approximately circular Glen Helen meteorite (12) and disc shaped, but quite irregular in outline and thickness. The average diameter is 82 cm and it weighs The Glen Helen meteorite was reputedly found near 81 kg. There are three irregular ablation holes, the largest 23°41’S 132°40’E in the Glen Helen area of the MacDonnell measuring 40 x 20 cm, and the other two measuring Ranges by an Aborigine and came into the possession of Mr 2–5 cm diameter. There are numerous other smooth cm- PD Boener of Alice Springs. He gave it to Drs Henderson, to dm-scale scoops or notches, also interpreted as ablation Mason and Mr Chalmers from the Australian Museum features. The surface is etched or pitted and dark grey/ while they were on their way to the Henbury site in 1963. brown in appearance with only minor surface crust. The It is believed to still be in the collection of the Australian outer edge has several sharp and angular wing-shaped Museum, but Fitzgerald (1979) could not locate it in the protrusions. It was one of these (Figure 13) that was mid-1970s, suggesting that it may have been miscatalogued. removed by hacksaw (see above). The internal texture is Very little is known of the Glen Helen meteorite except that shown in Figure 14. it is an iron and weighed 727 g. Fitzgerald (1979) suspected Marc Norman from the Research School of Earth that it was a transported part of the Henbury shower, but Sciences (Australian National University, written this has never been corroborated. communication) quoted John Wasson (UCLA) who analysed a sample and determined that the Gallipoli Gosses Bluff (Tnorala) impact structure (13) Station No. 2 meteorite is type IVb (High Ni, low Ga, Cu and Au). Specific assays are: Cr 264 ppm, Co 0.767 %, Gosses Bluff (Tnorala) is one of the best-known large Ni 15.64 %, Cu 2.2 ppm, Ga 0.24 ppm, As 0.38 ppm, W terrestrial impact structures in Australia because of its well 2.96 ppm, Ir 28.0 ppm, Pt 26.2 ppm and Au 0.0639 ppm. exposed and well studied central uplift. Aerial images are The Ni content is higher than that of Henbury (typically shown in Figure 15 and Figure 16. The site is known as about 7% Ni) and the 0.24 ppm Ga content of Gallipoli Tnorala to the Western Arrernte Aboriginal people and Station No. 2 is much lower than that of Henbury (typically is now included in the Tnorala Conservation Reserve. 18 ppm). Thus, both Gallipoli Station No. 1 and 2 might be According to Aboriginal culture, Tnorala was formed in part of a different shower to Henbury. However Gallipoli the creation time, when a group of women danced across Station No. 1 was described as a type IIIA; which if the sky as the Milky Way. During this dance, a mother put correct, would distinguish it from the Gallipoli Station her baby aside, resting in its wooden baby-carrier (a turna). No. 2 meteorite. The discovery of the Gallipoli Station The carrier toppled over the edge of the dancing area and No. 2 meteorite was not officially reported until 2008 and crashed to earth where it was transformed into the circular by that time, the main mass had apparently gone missing rock walls of Tnorala (Parks and Wildlife Commission from the station homestead. NT 2014). Despite the similarity of this story with an extraterrestrial origin, it is certain that no human witnessed the Gosses Bluff impact (Hamacher and Norris 2009). The first European to see the crater wall was probably Earnest Giles in 1872 who named it Gosse’s Range, but its circular structure, centred on 23°49’07”S 132°18”26”E, was not recognised by geologists until the late 1950s when it was interpreted as being a salt diapir like many others in the Amadeus Basin. The diapir hypothesis and gas blows in shallow seismic drillholes led to the drilling of the 1383 m Gosses Bluff‑1 petroleum well during 1965. In the Figure 13. Gallipoli Station No.2 meteorite polished slab same year, the crater was first photographed from space by (photograph by P Haines). astronauts aboard the Gemini V spacecraft. This showed faint relics of its eroded outer rim surrounding the better known central uplift. Its impact origin was first recognised when Crook and Cook (1966) and Dietz (1967) documented and correctly interpreted shatter cones. The structure was comprehensively studied using surface studies, drilling and geophysical techniques over the next two decades. The petroleum potential was reassessed after the acceptance of an impact origin and Gosses Bluff‑2 was drilled to 2652 m in 1988. The key references for Gosses Bluff impact structure, Milton et al (1972), Milton et al (1996a, b), were based on joint work between the US Geological Survey (on behalf of NASA) and the Australian Bureau of Mineral Resources, and document both the geophysics and geology. Gravity data outlines a symmetrical circular gravity low Figure 14. Gallipoli Station No.2 photomicrograph of polished of 440 μms-2 with a radius of 10.8 km. The centre of the section (photograph by P Haines). Image is 250 µm wide. uplift itself has a small positive gravity anomaly of up to

13 NTGS Record 2014-007 a

b

Figure 15. Gosses Bluff impact structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Astrium 2014). (b) Residual gravity map, contour units in 0.2 µm s-2 (after Milton et al 1996a).

NTGS Record 2014-007 14 +8 MGal relative to the annular low (Hawke 2004). The rim has been interpreted to have been ca 24 km in diameter centre of the structure corresponds to a negative magnetic on geophysical grounds (Milton et al 1996b). anomaly of 4 nT. Seismic data shows continuous reflectors The crater is located on Missionary Plain, a flat-floored below about 3500 m, which is interpreted as the depth limit syncline in the northern Amadeus Basin. As mapped at of subsurface structural disturbance. The now eroded crater surface (Figure 17), the structure consists of a prominent

Figure 16. Oblique view of Gosses Bluff impact structure looking north (after Google earth, DigitalGlobe, CNES/ Astrium 2014).

?

23°47'

creek

Gosses Bluff-2

23°50' ?

Gosses Bluff-1

23°53' 03 km

132°15' 132°18' 132°21' 132°24'

Cenozoic Devonian alluvium Pertnjara Group (upper) Larapinta Group red-brown conglomeratic sandstone red-brown siltstone and silty sandstone aeolian sand (equivalent in part to Carmichael Sandstone red-brown poorly sorted sandstone and Stokes Formation travertine - pebbly in places red-brown and green micaceous sandstone, siltstone, limestone (equivalent in conglomerate siltstone; minor thin sandstone part to Stokes Formation and Stairway conglomerate and conglomeratic Pertnjara Group (lower) Sandstone) sandstone - poorly consolidated brown or red-brown sandstone and geological boundary silty sandstone breccia fault breccia; massive clasts; some red siltstone and sandy siltstone associated finer breccia abandoned oil well breccia clasts of sandstone and Silurian–Devonian shale in a sandy mix Mereenie Sandstone airstrip white or pale brown, cross-bedded sandstone A14-170.ai Figure 17. Geological sketch map of Gosses Bluff impact structure (after Milton et al 1996a).

15 NTGS Record 2014-007 4.5 km diameter circular ridge, 180 m high. This circular The melt breccia, probably derived mostly from Parke ridge is an eroded remnant of the central uplift and is Siltstone, records high shock temperatures. Quartz has composed of brecciated Ordovician to Devonian sandstone been transformed to glass, partly recrystallised to tridimite and shale, with intersecting rhombohedral cleavage, (stable at low pressure between 867°C and 1470°C) and striated fracture patterns and fully formed shatter-cones subsequently converted to solid-state diaplectic quartz. The (Figure 18). fusion of shale resulted in potassium-enriched hot solutions Annular troughs contain megabreccia, breccia and circulating below the crater floor and recrystallisation into melt breccia. Breccia dykes are also present, and with pumiceous aggregates of sanadine, zeolites and hematite. only rare exceptions, are monomictic. Clasts range up to 39Ar/40Ar plateau ages of this sanadine-rich material suggest hundreds of metres across, but are typically <0.5 m. The recrystallisation at 142.5 ± 0.8 Ma, near the Jurassic– megabreccia is probably equivalent to zones of overturned Cretaceous boundary, which is consistent with other blocks and plates of Mereenie Sandstone at higher levels geological constraints. of the ridge. Analogy with the Acraman impact structure in South A prominent hill, Mount Pyroclast, a few kilometres Australia where ejecta has been found in contemporaneous south of the main ridge, displays a lower recrystallised sites of sedimentation up to 550 km away (Hill et al 2008), quartzitic breccia which shows conchoidal fractures suggests that similar ejecta or geochemical anomalies consistent with shock-heating. This is overlain by melt should be present in Jurassic-Cretaceous rocks of the breccia at least 14 m thick and partly fused rock, that together Eromanga Basin, but there has been no systematic search constitutes most of the hill. The melt breccia consists of to date. Calculations indicate that the projectile ( or partly melted fragments of recrystallised sandstone, baked ) that produced the Gosses Bluff structure would mudstone, and lumps of devitrified silica glass embedded in have been about 2 km in diameter and that, after allowing a flow-banded matrix of devitrified silica glass. Melt breccia for erosion, the impact deformed the crust to a depth of over higher on the slopes of Mount Pyroclast contains fragments 5 km. a few centimetres across, many of which are vesicular and pumiceous, or have flowed into twisted ropy folds. Gove meteorite (14) The shatter cones present in the central ridge have been described in detail by Milton et al (1996a). Cone textures, As far as the authors are aware, the Gove meteorite is only typically 20 cm to 30 cm long, are well developed in mentioned in 1997 correspondence from Alex Bevan, Curator sandstone, limestone, mudstone, conglomerate and shale. of Mineralogy and Meteorites, Department of Planetary Two metre-long segments occur in the more massive and Earth Sciences of the WA Museum, in conjunction with sandstone. Cones which radiate or spiral over a full 360° are the Kurinelli meteorites, and is coincidentally mentioned rare. Shatter cones are also common in breccia clasts, but in Megirian (1998). In a brief description, Bevan mentions do not extend into the breccia matrix. Microscopic textures a deeply weathered iron meteorite discovered in bauxite in quartz in both breccia and target bedrock show shock- at Gove and noted that it had not been described in the induced fractures and planar deformation features. No scientific literature. The Museum of Victoria’s meteorite coesite or stishovite has been found. The textures observed database has two references to meteorites from Gove, both are consistent with shock exceeding 20 GPa. found in the Nabalco Bauxite Mine:

Figure 18. Gosses Bluff shatter cones (photograph courtesy of Mike Freeman in Edgoose and Haines 2012).

NTGS Record 2014-007 16 • Gove iron octahedrite 111AB Australia: registration of ‘one of the most curious spots I have ever seen in the #E 18381, location 12°10’48”S 136°46”12”E (Museum country’. Park described the craters to Gillen but did not Victoria 2014a) know what had caused them. Park went on to say, ‘To look • Gove iron octahedrite Na Australia: registration at it I cannot but think it has been done by human agency #E12521, location 12°10’48”S 136°46”12”E; weighing but when or why Goodness knows’ (Mulvaney et al 1997, 0.304kg, found July 1979 (Museum Victoria 2014b). Parks and Wildlife Commission of the NT 2002). Fitzgerald (1979) cited evidence that some Henbury No other details are available. meteorite material may have been discovered by Europeans as early as 1902 and collected as a curiosity without knowing Goyder impact structure (15) its real significance. Certainly by 1916, the craters were a well known landmark to prospectors and pastoralists. The Goyder impact structure in situated in Mesoproterozoic More insightfully perhaps, the actual impact event may rocks of the Roper Group in the northern McArthur Basin be recorded in the oral tradition of the local Aborigines. (Figure 19). Peter Haines first identified a circular structural The Arrernte name for the crater field is Tateye Kepmwere anomaly at 13°28’30”S 135°02’30”E on aerial photographs (Tatjakapara) and according to 1930s descriptions, the while preparing for joint geological mapping by NTGS and Aborigines referred to the craters as chindu china aru the Australian Geological Survey Organisation. Haines chingi yabu, roughly translated as “sun walk fire devil later visited the site by helicopter, confirming a meteoritic rock” (Anonymous 1932, Hamacher and Norris 2009). origin and named the structure after the nearby Goyder These stories apparently describe the craters as having River (Haines 1996, 2005, Haines et al 1999). been caused by a fire devil coming from the sun many The following discussion is based on these references. generations prior to European contact. Furthermore, some The surface expression is a nearly-circular structural uplift, sources say that the Aborigines did not drink the water from about 3 km in diameter, consisting of an outer annulus of the craters in fear that the fire devil would fill them with Hodgson Sandstone with a central hilly region, 1.5 km iron (LJ Spencer, addendum in Alderman 1932, Fitzgerald in diameter, consisting of radially-faulted sandstone and 1979). However, apparently not all local Aboriginal people mudstone of the Arnold Sandstone and overlying Jalboi shared this apprehension and Brown (1975) noted that the Formation. This sandstone is generally fractured to varying Henbury craters were in fact an important Aboriginal water degrees and microfracturing is also common. Striated source. Another Aboriginal story regarding the origin of fracture surfaces occur sparsely throughout this central the craters given in Mountford (1976) does not attribute the area, but well developed shatter cones are present at only one craters to a cosmic impact. locality, very close to the centre. Individual cones are about In the early 1930s, public interest in meteorites and 50 cm long and most in situ examples appear to be oriented impact structures was stimulated by the fall of the Karoonda roughly parallel to bedding. The outer annulus of Hodgson meteorite in South Australia on November 25 1930 and its Sandstone is about 300 m to 400 m wide. It consists mostly of discovery by an Adelaide University party led by Professor loose sand (disintegrated sandstone), but contains scattered Kerr Grant. This led to rekindled interest in the Henbury outcrops of fractured and brecciated sandstone, generally meteorite craters, when Mr B Bowman of Tempe Downs dipping tangentially outwards. Thin section petrography and Mr J H Mitchell of Oodnadatta separately informed confirmed the presence of shock-induced planar deformation Grant in 1931 of the presence of craters with scattered iron features at the central shatter cone locality. fragments near Henbury Station. On the advice of Professor The outcropping structure is interpreted as the erosional Sir Douglas Mawson, the Honorary Mineralogist to the remnant of the central uplift of a ; the original South Australian Museum, Dr AR Alderman, assisted by rim is estimated to have been between 9 km and 12 km Mr PL Windsor, was commissioned to make an examination in diameter. The time of impact is poorly constrained to of the area. <1325 Ma ago, but is probably older than Cretaceous because it The craters were known locally as ‘The Double lies on an exhumed Cretaceous land surface and undeformed Punchbowl’, referring to the two largest craters. The gap Cretaceous sedimentary rocks are present nearby. in the Bacon Range where the access road now passes through was then known as ‘Double Punch Gap’ (Parks and Hart (or Harts) Range meteorite (16) Wildlife Commission of the NT 2002). It was not until late 1931 that Alderman (1932) confirmed the craters as being The Hart (or Harts) Range meteorite was reputedly found of meteoritical origin and documented the presence of near 23°S 131°E by persons unknown. It is a medium meteorite fragments. Alderman’s expedition was followed octahedrite and 608 g are kept in the Western Australian shortly afterwards by several expeditions led by Mr R Museum. De Laeter (1973), Fitzgerald (1979) and others Bedford of the Kyancutta Museum. concluded that it was part of the Boxhole shower and it has Many of the best specimens from the Bedford been synonymised with that. expeditions were sent to the British Museum. The Alderman and Bedford expeditions were described by Henbury (Tatjakapara) craters and meteorites (17) Fitzgerald (1979). These and other early scientific search parties for museums are reported to have recovered 1447 The Henbury craters (Tatjakapara) (Figure 20; 24°34’20”S individual fragments of meteorites, ranging in weight 133°08’54”E) have been known since 1899 when the from less than a gram to 132 kg. Once the value of the manager of Henbury station, Mr Park, informed FJ Gillen meteorites was realised, there were disputes between the

17 NTGS Record 2014-007 a

b

MANINGRIDA

Arnhem Highway JABIRU

Kakadu Highway Goyder Impact Structure 35 ALYANGULA

40 13°28'S

20 20 20 20 35

Cenozoic 60 20 alluvium

Mesoproterozoic 50 35 Bessie Creek Sandstone

13°29'S Corcoran Formation

Hodgson Sandstone

30 40 Jalboi Formation

Arnold Sandstone

40 dip and strike of strata shatter cone locality 01 km fault ephemeral water course A09-185.ai

135°02'E 135°03'E Figure 19. Goyder impact structure. (a) Satellite image (after Google earth, CNES/Spot Image 2014). (b) Impact structure simplified geology (after Haines 1996).

NTGS Record 2014-007 18 pastoralist, various scientific expeditions, local aborigines missions. The key references are Alderman (1932), Hodge who collected pieces for museums and for sale to collectors, (1965), Hodge and Wright (1971), Milton (1972), Fitzgerald and individuals and parties acting under Miners Rights. (1979), McColl (1990), Bevan (1996) and Haines (2005). A pegging rush of mineral leases to secure title added Most workers agree that there are at least 13 discrete craters to the conflict. The floors of many of the craters were hosted in Neoproterozoic sandstone and mudstone of the haphazardly excavated and the craters themselves were Amadeus Basin and surficial cover. Crater diameters range damaged in the search for meteorites. In addition, there from 6 m to 180 m, the largest being an elongate double- was a dispute about the large amount of material being impact site. The larger craters are classic bowl-shapes with shipped overseas, mainly to the British Museum, because overturned flaps around the rims and are undoubtedly true the South (who then administered explosion craters. One crater in particular displays a well the NT mineral titles) maintained that the meteorites were developed down-range ejecta ray. the property of the state and that all exports and sales were There is a geophysical radiometric potassium anomaly illegal. Sir Douglas Mawson was called in to mediate a at the craters’ location (Figure 21), which is likely reflecting solution and a temporary reserve was declared in 1932. potassium-bearing clay minerals dispersed by the impact. Only surface collecting was permitted. The area was then The discovery of large buried meteorite masses in several amicably but intensively worked by both scientific parties of the smaller carters suggests that these are better described and private collectors for several decades. as fragmentation pits. For example, a fragment weighing The Australian Museum and the Smithsonian Institute 18 kg was recovered from one crater and a 132.7 kg mass mounted a joint expedition in 1963, during which over 600 was retrieved from another. At the time of discovery the specimens ranging in weight up to about 1 kg were collected. area was littered with iron meteorite fragments and droplets The Victoria, Tasmanian and Powerhouse Museums also of black impact glass with the greatest concentration down- have good meteorite specimens. The latter also has black range of the larger craters. McColl (1990) documented silica impact glass. The Smithsonian and Chicago Field meteorite fragments being found more than three kilometres Museums have numerous individual stones, fragments from the craters. and polished slabs. The former retains the largest known Some typical meteorites are shown in Figure 22. A accurately weighed single mass of 180.9 kg (Fitzgerald few subsurface specimens are heavily oxidised, but most 1979). The MAGNT has a 44 kg fragment on display in the specimens only have superficial rust. The iron meteorite Alice Springs Museum. At least 26 other museums around is a group IIIAB medium octahedrite with a band width the world have samples and considerable material is held of 0.95 ± 0.1 mm. Taylor and various colleagues undertook in private collections. Many of the specimens currently for geochemical studies of the meteorites and impact glass sale by collectors were taken from the site in the early 1970s during the 1960s and 1970s (eg Taylor and McLennan (before the current Meteorites Act) using metal detectors. 1979). Fitzgerald (1979) also gave a comprehensive listing The Henbury site is one of Earth’s best examples of a of references to elemental assays available to that date. He small crater field and one of the best studied. It was used as cautioned that some analyses attributed to the Henbury a training site to develop procedures for the Apollo moon meteorite may have been carried out on mislabelled

Figure 20. Henbury impact craters (after Google earth, DigitalGlobe 2014).

19 NTGS Record 2014-007 specimens. Values of 7.47% Ni, 17.7 ppm Ga, 33.7 ppm Ge indicate that the fragments separated from the crater- and 13 ppm Ir from Scott et al (1973) are commonly cited producing projectiles during atmospheric entry, and thus as typical. avoided deformation during the impact explosions. Both distorted and undistorted material has been Alderman (1932) and McColl (1990) described three documented. Although most fragments show considerable types of glassy fragments. The most common are rounded impact-induced deformation, there is an enormous range of masses of frothy to scoriaceous black glass that are internal structures. The most severely deformed specimens sometimes red internally. Specimens range up to 8 cm have a high density of sheared surfaces, at both the in diameter. A second type comprises angular fragments, macroscopic and microscopic scale. The interior structures usually no more than 3 cm across, of black glass with a of deformed fragments show intensely bent and kneaded smooth vitreous surface. The third type, glass-coated rock Widmanstätten patterns and varying degrees of annealing. fragments, includes irregular to subrounded fragments of

In other examples, kamacite is transformed to α2-kamacite baked shale, up to 10 cm x 4 cm in size, that are coated with and the Widmanstätten structure is partly resorbed. Troilite vitreous impactite glass from 0.5 mm to 3.0 mm thick. and schreibersite have been shock-melted and smeared out The age of the Henbury craters is interpreted as into veins. Schreibersite has been largely resorbed in the 4.2 ± 1.9 ka based on the cosmogenic 14C terrestrial age of most intensely shock-heated fragments. In contrast, other the meteorite (Kohman and Goel 1963). fragments retain regmaglypts, remnants of fusion crusts The crater field is interpreted to be the result of the and have unaltered Widmanstätten patterns. These features atmospheric breakup of a meteorite travelling obliquely

a b

Figure 21. Henbury impact craters. (a) Radiometric anomaly for potassium (NTGS GIWS 2014). (b) Satellite image (after Google earth, DigitalGlobe 2014).

Figure 22. Henbury meteorite fragments (photograph courtesy of MAGNT).

NTGS Record 2014-007 20 from the southwest. The Henbury site is now a conservation site, considered that it was highly unlikely that any crater reserve and an Aboriginal Sacred Site. would be preserved given the great antiquity of the fall. The meteorite had been a landmark for cattle mustering and Huckitta meteorite (18) the original photo of Madigan and Alderman shows that the area had been disturbed by cattle. The supposed crater may Local aborigines knew of the existence of the Huckitta be a modern aeolian affect or may reflect the differential meteorite before European colonisation. It was brought to weathering of the surrounding iron-rich shale described the attention of the cattle station owner, Mr W Madrill, by below. an aboriginal employee named Mick Laughton. A sample As described by Madigan and Alderman (1939), the obtained by Laughton was shown to the geologist CT meteorite contained large olivine crystals up to several Madigan in 1939 who recognised it as being of meteoritic centimetres across which were preferentially weathering origin. out. The longest dimension of the exposed meteorite was Madigan and Alderman (1939) document the recovery 1.3 m and the greatest girth 2.1 m. The meteorite was deeply and study of the meteorite as follows. The site is still weathered and found to be surrounded by extremely hard generally cited as being 22°22’S, 135°46’E as per Madigan’s iron-rich shale. dead reckoning, but it was relocated by Mike Freeman, then It was estimated to have originally been at least eight at NTGS, more precisely at 22°17’14.5’S 135 °45’16.3”E. times its present size and must have weighed over 10 t at Madigan’s team located and photographed the site with the impact. After considerable effort to extricate the main meteorite in situ (Figure 23). unweathered mass, it was found to weigh 1415 kg. In In their opinion, the meteorite stood in a very shallow addition, a 927 kg sample of iron-shale was recovered. Once crater, on a plain of sandy gravel. A distinct rim some in Adelaide, a special diamond saw had to be constructed to tens of centimetres high surrounded the meteorite at a cut the meteorite. distance of 1.5 m. The crater was thought to be elongated Typical examples of a fresh polished surface are shown in the direction of the long axis of the meteorite and this in Figure 24. Kamacite, plessite and lawrencite have been was interpreted as the meteorite arriving from the west- documented. All plessite areas are edged with a bright southwest. However, Megirian et al (1987) who revisited the white line of taenite. A Widmanstätten pattern is readily distinguishable. Troilite is intergrown with olivine, and also occurs as separate grains. The remainder and majority of the separate grains are schreibersite. A unique feature of the meteorite is the -like aggregates of olivine and troilite in approximately equal amounts, the grain-size of each being less than a millimetre. Some of the have the appearance of a eutectic crystallization of olivine and troilite. The chemical composition of the metallic portion (excluding olivine), based on Madigan and Alderman’s (1939) original work, is 89.36% Fe, 8.98% Ni, 0.45% Co,

0.02% S, 0.47% SiO2 and insolubles, with a trace of P. This composition is similar to the Burt Plain meteorite with which it may share an affinity. Wasson and Choi (2003) included the Huckitta Figure 23. Huckitta meteorite in situ (Madigan and Alderman 1939). meteorite in their comparative geochemical study and noted

a b

Figure 24. Huckitta meteorite polished samples. (a) Close up of polished surface (photograph courtesy of Geoffrey Notkin, copyright Oscar E. Monnig Meteorite Gallery, Christian University). (b) Fragment (photograph courtesy of the Oscar E. Monnig Meteorite Gallery, Texas Christian University).

21 NTGS Record 2014-007 high values of Ge and Ga. The assay showed 7.79% Ni, as a possible indicator of deeper gold mineralisation. They 26 ppm Ga, 65 ppm Ge and 0.94 ppm Ir. would normally smash up the ironstone, either in the hope The Huckitta meteorite is regarded as belonging to the of finding visible gold or to pan the powder. In September Pallasite-Main group and is the largest of this type known. 1996, Ray Hall, a local prospector and miner, approached The main mass of the meteorite is still held in the Nick Byrne of Giants Reef Mining NL (and other Museum of South Australia, but specimens are also held companies) with the assay results of what appeared to be an in the Museum of Victoria, Australian National University, atypical fragment of ironstone that assayed 4% Ni, 2 ppm and across the world, including the Monnig Collection (Fort Pd and 1.5 ppm Pt in addition to the more usual 2 ppm Au, Worth, Texas), Arizona State University, the British Natural 350 ppm Cu, 200 ppm Mn and 0.18% Co. On examination History Museum, Max Planck Institute, Smithsonian of the specimen, Byrne suspected that it was a meteorite National Museum of Natural History, and the Chicago Field fragment. Shortly thereafter, another prospecting syndicate Museum of Natural History. led by Tony Campbell approached NTGS with a similar ironstone sample. NTGS also identified the sample as a Kelly West impact structure (19) meteorite. However, local prospectors had taken the news of high Ni assays as indicative of a bedrock Ni occurrence The Kelly West impact structure (Figure 25) is centred at and a flurry of lease-pegging ensued. 19°55’46”S 133°57’05”E, about 40 km south-southwest of Norm McCleary (McCleary Investments Pty Ltd, a . It was first recognised as being of meteoritic predecessor of Arafura Resources Ltd) and Homestake origin after the discovery of shatter cones during regional Gold of Australia Ltd commissioned further work including mapping by the Bureau of Mineral Resources (Tonkin 1973). numerous analyses, a petrological study and laser ablation The other key references are Shoemaker and Shoemaker work (Kelvin Hussey, Arafura Resources ltd, in litt August (1996) and Plescia (2006). 2008, John Goulevitch, Arafura Resources Ltd, in litt The original size of the impact crater is uncertain March 2009). The then Department of Mines and Energy because of erosion, structural complexity and surficial sent geologist John Canaris to investigate and while he cover. Shatter cones are distributed over the entire 2 km long was doing so, a second check sample from Ray Hall was exposure of target sandstone but this is interpreted as only assayed and found to contain 3.19% Ni, 43.3% Fe, 1698 ppb the central uplift, with no exposed geological constraints on Pt and 921 ppb Pd. That the unusual ironstone fragments the location of the original rim. After mapping the central that prospectors found and termed “magnetic ironstone” uplift, Shoemaker and Shoemaker (1996) estimated that the were not vectors to underlying hard-rock mineralisation, whole structure may be greater than 8 km, but probably less but were in fact meteorites was independently determined than 20 km across (Figure 25b). by at least six people: Colin Wessels and John Goulevitch, The centre of the structure coincides with a +0.8 mGal who used concentrated acid to etch a sample to reveal annular gravity high and there appears to be some annular the internal texture; John Canaris and Roger Townsend, disruption of the magnetic response (Hawke 2004). Based based on petrography; John Love, based on geochemistry; on the gravity data, Hawke (2004) and Plescia (2006) and John Fabray, who hand-polished a slice to show the inferred an original diameter of 6.6 km. Widmanstätten pattern. Uplift of Hatches Creek Group quartz sandstone target Peter Simpson of Giants Reef Mining documented parts rocks has unfolded a pre-existing syncline. This uplift is of this story in a memorandum to the Western Australian demonstrated by the rotation of shatter-cone axes and Museum to accompany submission of a sample. Once outward-plunging radial folds along the southeast flank the significance of the magnetic ironstone fragments was of the uplift and the duplication of strata by overthrust realised, Ray Hall, Tony Campbell, Peter Simpson, John displacement toward the centre of the uplift. Close to McDonald and others donated material to what is now the the centre of the structure, the exposed Hatches Creek MAGNT, as is now required by legislation. Group sandstone is intensely brecciated. Flat-lying middle A brief visit was made to the Kurinelli meteorite field by Cambrian sedimentary rocks that are not shatter-coned, MAGNT staff, D Megirian and P Murray, in the company overlie the Hatches Creek Group in the central uplift, of Peter Simpson, between 11 and 14 May, 1998. They made thereby dating the impact event as some time between the direct contact with some of the finders, and assessed what Palaeoproterozoic and the early Cambrian. future work might be carried out by MAGNT in order to best meet the objectives of the Meteorites Act 1988. Kurinelli meteorites (20) Megirian (1998) documented the very limited work undertaken on the Kurinelli meteorites. Unbroken fragments The Kurinelli meteorites are a collection of octahedrite iron typically have blocky shapes with irregular, rounded-off meteorites now almost completely oxidised (Figure 26), surfaces. The outer weathered surfaces are typically highly found during gold prospecting on the Kurinelli goldfield, polished. Internally, they are lustrous dark grey to grey, centred on 20°37’S 135°03’E, about 150 km southeast and veined by brown and red-brown secondary iron. The of Tennant Creek. As far as the authors are aware, these mineralogy is dominated by oxidised compounds of iron meteorites have only ever been publicly documented by (hematite, magnetite, maghemite, goethite, limonite) with Megirian (1998). traces of chromite and quartz, and rare iron-nickel alloy. Since gold in the Tennant Creek field is commonly Troilite also has been reported. Very basic polished and hosted in stratabound ironstone, prospectors had long thin-section descriptions, lodged with the MAGNT, are been collecting fragments of ironstone from the surface included in Megirian (1998).

NTGS Record 2014-007 22 a

133°57' b LOCALITY MAP Stuart Highway

Barkly Highway

TENNANT CREEK alluvium

25 km Kelly West Kelly Well Cenozoic colluvium

laterite middle Gum Ridge Formation 50 15 20 Cambrian (chert and limestone) 20 20? Proterozoic(?) sedimentary breccia 15? authigenic breccia upper red sandstone 10 20 shale 40 70 70 conglomeratic brown sandstone 15 25 white sandstone 80 70 35 30 Palaeoproterozoic 30? lower red sandstone 25 30 Hatches Creek Group 30 45 25 anticline (showing plunge); 35 dotted where concealed 40 20 syncline (showing plunge); 20 20 dotted where concealed 35 19°56'

normal fault (tick on down dropped 15 side); dotted where concealed thrust fault (teeth on upper plate); 20 70 dotted where concealed bedding strike, dip 15 crush zone 70 bedding, horizontal bedding strike, dip 15 joint with dip shatter cones bedding, horizontal drainage pattern joint with dip shatter cones 00.5 1 km drainage pattern A09-180.ai Figure 25. Kelly West impact structures. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Astrium, CNES/Spot Image 2014). (b) Impact structure geology (after Tonkin 1973, Shoemaker and Shoemaker 1996).

23 NTGS Record 2014-007 Figure 26. Kurinelli weathered iron meteorite sample held at MAGNT (photograph courtesy of MJ Barritt). In an interview with MAGNT staff, Mr Peter Saint, The structure was first noted by geologists during owner of Kurundi Station, reported that meteoritic material reconnaissance mapping and was labelled as a possible has also been found as far as 200 km from Kurinelli at meteorite crater by Rix (1965). Investigations by Brett et Annitowa. MAGNT found no signs of an impact structure at al (1970) and Guppy et al (1971) supported a meteoritical Kurinelli itself, nor is there any obvious geomorphological origin. Shoemaker and Shoemaker (1997), Shoemaker et al control on the distribution of the meteorites. The Wessel (2005) and Haines (2005) are more recent key references. structure is less than 4 km away and Arafura Resources The target stratigraphic succession comprises have speculated that this might be an impact structure relatively flat-lying Gumarrirnbang Sandstone of the related to the meteorites (Kelvin Hussey, Arafura Resources Palaeoproterozoic Kombolgie Subgroup (Figure 27b). An Ltd, in litt March 2009); however the relative ages are too outer breccia zone contains two distinct breccia units. An inconsistent for this to be likely. authigenic breccia is comprised of deformed and upturned The meteorite material occurs in the soil profile rather target rocks, commonly with large structurally coherent than at the surface, suggesting that the fall is of considerable zones. A more voluminous allogenic breccia overlies antiquity. Most of the material now held in the MAGNT is the former with a sharp and commonly slickensided fragmentary, and for the most part, adequate locality data (schliffläche) contact. Clasts in the allogenic breccia range are not available. Tenement holders at Kurinelli commonly from sand-sized to blocks several metres across. worked a particular area in a partnership, so it cannot The asymmetry of the crater, thicknesses of the breccia be assumed that any particular specimen comes from a units, and other structural evidence suggests that the tenement held by the collector. Furthermore, the material impactor had a low-angle trajectory from the southwest was not collected with meteoritical research in mind, and (Shoemaker and Shoemaker 1997). consequently collection data is minimal and commonly An undeformed post-impact sedimentary rock partly only broken fragments of the original specimen have been infills the crater and onlaps the breccias. This sedimentary retained. rock is critical for determining the time of the impact, but Further investigation into the distribution of the currently lacks any biostratigraphic or chronostratigraphic meteorites, including verification of Peter Saint’s report control (Carson et al 1999). Guppy et al (1971) considered it that meteorites have been found well beyond the Kurinelli to be Cretaceous, which has resulted in the commonly quoted goldfield, is warranted. It is through such information that Cretaceous age for the impact. However, Haines (2005) the extent of the original fall, and/or the factors controlling its considered that it was more likely to be the Neoproterozoic present terrestrial distribution might be elucidated. Specimens Buckingham Bay Sandstone of the basal Arafura Basin, with an adequately documented provenance are essential. which would constrain the impact to the Proterozoic and Apparently quite large masses have been found, but all the would mean that Liverpool crater may be the world’s oldest material now held MAGNT is either small, sawn, or smashed well preserved simple impact crater. (Megirian 1998). There have not been sufficient modern geochemical studies to assign the Kurinelli meteorites to any Matt Wilson impact structure (22) group. Nor are there any modern petrological descriptions or studies of the Widmanstätten texture. The Matt Wilson impact structure is a 6.3 km x 7.5 km ring monocline (Figure 28) centred on 15°29’36”S 131°11’23”E Liverpool impact crater (21) in Judbarra/Gregory National Park. It was mapped as a dome on first edition mapping in DELAMERE and is The Liverpool crater is situated at 12°23’46”S 134°02’50”E apparent as an annular negative anomaly on first vertical- on the boundary between the McArthur Basin and the derivative (1VD) airborne magnetic images. Ian Sweet and overlying Arafura Basin. It has a classic crater shape with Peter Haines re-interpreted it as a possible impact structure a circular raised rim 1.6 km in diameter (Figure 27). In and confirmed this during a field visit by Sweet in 2003. Aboriginal culture, the crater was formed as the nest of Haines (2005), Sweet et al (2005) and Kenkmann and a giant catfish. This is supported by pictographs of giant Poelchau (2009) are the principal references. catfish on the walls of a rock shelter within the crater The structure lies in the regionally horizontal to gently (Shoemaker and Macdonald 2005). dipping Wondoan Hill and Stubb formations (Tijunna Group

NTGS Record 2014-007 24 a

134°2'30"E 134°3'0"E

b ARAFURA SEA 60

MANINGRIDA 40 30 50 23 20 JABIRU Liverpool 20 Impact Structure 10 23 22 22 24 12°23'30"S 22

4 20 25 5 25

17 7 4 13 9 12 15 30 15 15 4 9 9

12 10 22 9 87 4 4 5 10 5 45 22 7 12°24'0"S 23 15 5 9 18 9 20

20 20 16 46 22

bedding with dip

overturned bedding

limit of deformation 2 7 A09-184.ai

alluvium upper crater fill allogenic breccia Cenozoic 0400 m laterite lower crater fill authigenic breccia Gummarriirnbang Mesoproterozoic sandstone Figure 27. Liverpool impact crater. (a) Satellite image (after Google earth, DigitalGlobe 2014). (b) Impact crater geology (after Shoemaker et al 2005).

25 NTGS Record 2014-007 a

A'

b A' A profile line anticline with plunge direction of fold axis

syncline

fault Cenozoic

Neoproterozoic upper thin bedded JGS (Jasper Gorge Sandstone) white marker JGS lower thin bedded JGS massive JGS Mesoproterozoic Stubb Formation Wandoan Hill Formation

01 km

A crater rim ring syncline central uplift ring syncline crater rim SW A NE

A14-175.ai

Figure 28. Matt Wilson impact structure. (a) Satellite image (after Google earth, CNES/Astrium 2014). (b) Impact structure geology (after Kenkmann and Poelchau 2008).

NTGS Record 2014-007 26 of Birrindudu Basin) and Jasper Gorge Sandstone (Auvergne cluster, and has been correlated with the early Neoproterozoic Group of Victoria Basin). A central zone, about 1.5 km Supersequence 1 of the Centralian Superbasin based on across, is marked by steeply dipping to overturned Tijunna comparisons of detrital zircon provenance data (Carson Group and possibly underlying Bullita Group sandstone and 2013). The presence of a widespread, single thin interval mudstone, and indicates an uplift of at least 300 m. The inner of soft-sediment deformation features in the Saddle Creek part of the central uplift shows stacking of moderately to Formation, some 700–1000 m stratigraphically higher in steeply dipping thrusts of Wondoan Hill Formation. These the Auvergne Group than the rocks at the impact site and thrusts are folded along steeply plunging axes in the centre of apparently increasing in thickness towards the Matt Wilson the structure and the most prominent breccia zones (polymict structure, led Sweet et al (2005) to speculate that this may and monomict) occur between thrust slices (Kenkmann be the impact event horizon; if correct, the impact would and Poelchau 2008, 2009). This central zone is surrounded have most likely occurred during the early Neoproterozoic. by an intermediate zone with faulted sandstone displaying horizontal to low dips, and an outer circumferential syncline Mount Sir Charles meteorite (23) with dips of 5–40° in the limbs. Several thrust faults in the outer syncline appear to The Mount Sir Charles meteorite was found in 1942 by indicate outward-directed forces. The rocks in the central T Williams at 23°50’S, 134°02’E, 11 km east of Bond zone are intensely fractured with some brecciation, and Springs Station. It was initially named Bond Springs until contain numerous planar to subtly undulating surfaces it was discovered that this name had already been used for displaying striae that resemble shatter cleavage rather than another meteorite found 40 km way. The Mount Sir Charles classic shatter cones (Figure 29). meteorite originally weighed 22.9 kg and was acquired by Thin-sections of sandstone from the central area show Mr NC Bell of Alice Springs, who gave 22.23 kg to the zones of intense microbrecciation and irregular and planar South Australian Museum, where it remains. At least 600 g fractures in quartz. The planar fractures occur in multiple, had been removed prior to acquisition by the museum and intersecting parallel sets that are typical of relatively low- the history of this material is unknown, but it is presumably level (5–10 GPa) shock-pressure effects. Planar deformation the source of material attributed to this meteorite now held features in quartz have been documented by Kenkmann by the University of Adelaide, Smithsonian Institution,, and Poelchau (2009). No melt-rocks have been identified. and Australian National University. The Mount Sir Kenkmann and Poelchau (2008, 2009) and Poelchau Charles meteorite is an iron, type IVA fine octahedrite and Kenkmann (2008) used the Matt Wilson structure as an (Corbett 1968). Fitzgerald (1979) described a very fine, example of an elliptical crater with central uplift indicating wavy Widmanstätten pattern (bandwidth 0.22 mm), with oblique impact. They believed that it was a unique ancient no obvious troilite or other nodules. Fitzgerald (1979) example in that the preferred stacking of the central uplift also described its unusual shape as being part of the outer is additionally aligned with the long axis of the ring ellipse, spherical shell with the inner core missing, apparently giving two independent indicators for the axis along which having been removed by erosion. the impactor was travelling. The Matt Wilson structure most likely resulted from an impactor traveling at an angle of 10° Nutwood Downs meteorite (no location) to 15° and is now a deeply eroded remnant of the original impact structure, of which the more highly shocked rocks A medium octahedrite type IIIA meteorite called Nutwood of the original crater floor have been removed by erosion. Downs was reputedly found on the station of the same The age of impact is constrained between deposition name prior to 1971, possibly in 1970, by persons unknown. of the Jasper Gorge Sandstone and extrusion of the early The station manager knew nothing of the find and the exact Cambrian Antrim Plateau Volcanics. The Jasper Gorge location has never been stated. The meteorite was sold to Sandstone has a maximum depositional age of 1332 ± 22 Ma Mr David New, a New York mineral dealer, by a Surfer’s based on a weighted mean of the youngest detrital zircon age Paradise mineral dealer. Fitzgerald (1979) and others

a b

Figure 29. Matt Wilson impact structure outcrop photographs (Sweet et al 2005). (a) Closely spaced fractures in Wondoan Hill Formation sandstone. (b) Striated fracture surface.

27 NTGS Record 2014-007 synonomised it as part of the Henbury shower although Shoemaker (1996), Spray et al (1999a, b), Haines (2005) Henbury is classified as a type IIIAB. According to that and Zummersprekel and Bischoff (2005) are the key author, specimens are held in the Arizona State University references. (78 g) and the University of California (39 g). The area has been remapped several times and the target consists of relatively undeformed Mesoproterozoic Poeppel Corner meteorite (24) sedimentary rocks with interlayered dolerite sills, and underlying granitic basement (Figure 30b). Guppy et al A 277 g stone, found at 25°47’S, 137°56’E among sand (1971) described the central outcrops as and identified dunes by Peter May in October 1980, has been formally devitrified glass, crystallites of possible igneous origin named the Poeppel Corner meteorite. Grossman (2000) and unmelted fragments containing abundant evidence of is the key reference. The meteorite has been typed as an impact metamorphism. Shoemaker and Shoemaker (1996) L6 ordinary chondrite, with mineralogy given as olivine found that the suevite consists largely of shock-melted clasts

(Fa24.4±0.4), pyroxene (Fs20.7±0.3Wo1.6±0.3), plus metal-sulfide of quartzite, shale and granite. Some clasts are longer than a shock veins. The shock stage is S3 and weathering grade is metre and are drawn out and deformed by viscous flow. The W2 (T McCoy, Smithsonian Institute). Samples are held by suevite rests on granite breccia, shattered granite or shock- the Smithsonian National Museum of Natural History and melted granite. the South Australian Museum. Impact melt breccia near the centre of the structure is enriched in Ni, Cr, Ir, Os and Pd, presumed to be from Rabbit Flat meteorite (25) the impactor (Morgan and Wandless 1983). Ni and Ir are enriched up to 60 times and 20 times background, The Rabbit Flat meteorite was found in 1974 by a road respectively. maintenance crew working on the road between The Massive breccias with unmelted clasts of quartzite and Granites and Rabbit Flat at approximately 20°22’S granite rest on basement granite. These were interpreted by 130°07’E. Graham (1978) and Fitzgerald (1979) named Shoemaker and Shoemaker (1996) as return flow of material Mr PD Boener of Alice Springs as the source of discovery back into the transient cavity. information. The meteorite is typed as an olivine-bronzite The diameter of the exposed and eroded circular chondrite (H6) and weighs 295 g (Graham 1978). Several structure is 16 km. The original size of the crater rim was samples are kept in the Smithsonian National Museum of interpreted as 40 km or more by Shoemaker and Shoemaker National History. (1996), but this figure has not been supported by later workers. Spray et al (1999) estimated dimensions of 24 km Roper River meteorite (26) to 26 km, in general agreement with 26 km to 29 km by Zummersprekel and Bischoff (2005). The latter authors The Roper River iron meteorite is very poorly documented. calculated the vertical component of uplift in the centre as It was reportedly found by an Aborigine about 80 km from between 2.4 km to 2.7 km. Urapunga on the Roper River (Fitzgerald 1979). The find A Precambrian age is suggested by the overlap of location is given imprecisely as 15°S, 135°E and there is undeformed early Cambrian Antrim Plateau Volcanics. some confusion as to when it was discovered. Most sources Infrared laser spot fusion 40Ar/39Ar analysis on two impact cite 1953, but there is evidence that it was already in a melt lithologies and a highly shocked breccia clast gave a collection before 1927 and Fitzgerald (1979) attributed the combined Neoproterozoic age of 646 ± 42 Ma, consistent find to 1921. The meteorite is classed as an iron IIIAB, and with the stratigraphic constraints (Spray et al 1999a,b). The is distinct from other NT irons (Fitzgerald 1979). Fitzgerald anomalous geochemistry and ejecta associated with this (1979) described numerous Brezina lamellae of schreibersite impact may be detectable as an event horizon elsewhere. which interfere with the Widmanstätten pattern. No troilite However, the time of impact corresponds to a period of is visible. The Astronomical Research Network (2014) glaciation and to the deposition of a thick sequence of quotes their sample as assaying 9.8 %Ni, 18.1 ppm Ga, tillite, at least in the western NT. This would complicate 33.9 ppm Ge and 0.04 ppm Ir. Of the original ca 6.4 kg, any search. 5.7 kg is held by the Victorian Museum. A 38.05 g sample is held in the Chicago Field Museum and the Australian Tawallah Valley meteorite (28) National University has 133.7 g. The Tawallah Valley meteorite is an iron of type IVB Strangways impact structure (27) and has been described by Hodge-Smith and Edwards (1941). It was found at 15°42’S, 135°40’E in 1937 by a Mr The Strangways impact structure occurs within the Gordon or Condon (the name is not clear on the original McArthur Basin and is centred at 15°12’S 133°34’E. record). The constable at police station, Mr The structure is prominent on aeromagnetic datasets Heathcock, passed it on to the Australian Museum in and satellite imagery. Airborne geophysical data show 1939. As received, it weighed 75.75 kg but a small piece, concentric magnetic highs (Figure 30a). The structure probably about 200 g, had been removed previously by was first mapped and interpreted as an igneous collapse persons unknown. Hodge-Smith and Edwards (1941) feature (Dunn 1963). Guppy et al (1971) recognised it as an and Fitzgerald (1979) described the main mass as an impact structure from its prominent central uplift, shatter essentially flat trapezoidal body, 65 cm long and 38 cm cones, melt breccia, and shocked minerals. Shoemaker and wide, with varying thickness. The surface is generally

NTGS Record 2014-007 28 a

335000 340000 345000 350000 355000 360000 b Cenozoic alluvium and lake beds Cretaceous 8335000 sandstone, shale Cambrian Antrim Plateau Volcanics quartzite breccia impactites granite breccia 8330000 impact melt rocks Mesoproterozoic Abner/Bessie Creek undifferentiated Bessie Creek Sandstone Corcoran Formation 8325000 Roper Abner Sandstone Group Crawford/Mainoru formations Limmen Sandstone unassigned sandstone 8320000 Archaean granite and syenite

fault

8315000

8310000 Figure 30. Strangways impact structure. (a) Total magnetic intensity (TMI) image 05 km (after NTGS GIWS 2014). (b) Strangways geology (after Shoemaker and Shoemaker

8305000 A14-176.ai 1996 in Zummersprekel 2002).

29 NTGS Record 2014-007 smooth except for shallow inconspicuous regmaglypts. Watkin-Brown who sent it to the United States National Both the original crust and the heat-affected zone are Museum, where it was divided into three portions that were preserved. It has an ataxitic texture with an oriented sheen distributed to the Museums of Chicago, New York and broken by a few troilite inclusions. Kamacite spindles, Washington (Figure 32). A slice of the meteorite and a cast commonly with taenite rims, are present in a plessitic of the original are held by the Chicago Field Museum of matrix. Schreibersite is common. Fitzgerald (1979) Natural History. Other subsamples of the original were sent interpreted it as a “spallation” product from a cosmic to the Australian Museum and the Smithsonian Institute collision. As of 1979, the bulk of the specimen was held sometime after 1966. Geoscience Australia has 29.33 kg in the collections of Geoscience Australia, the Australian (Fitzgerald 1979). Material is also held in the collections Museum (Figure 31) and the Smithsonian Institution. The of the NSW Geological Survey, Sydney Mining Museum, Australian National University and Museum of Victoria the Natural History Museum, London and the RAS also hold material (177.9 g) in Australia. Fitzgerald (1979) Meteorite Collection, Laboratory of Meteoritics, Russia. listed several pieces in overseas collections. By Fitzgerald’s (1979) calculation, about 47 kg of the original find is unaccounted for. Despite being represented Yenberrie meteorite (29) in collections around the world, the Yenberrie meteorite has not been studied in detail, other than being classified as The Yenberrie iron meteorite was found by Mr John Hoare type IAB-MG. in 1918. It was buried in sandy soil at 14°15’S 132°01’E between Pine Creek and Katherine. The find location was POSSIBLE IMPACT STRUCTURES shown on a map in Spencer (1932). The meteorite consists of two pieces that fit together to give an irregularly shaped This section lists possible meteorites impact structures in body about 43 cm long that collectively weighs 132 kg. The the NT in alphabetical order. The letter after each name meteorite has a coarse Widmanstätten pattern of straight refers to the map location (Figure 1). bulky kamacite lamellae. Sharply defined Neuman bands are present, as are brecciated schreibersite and cohenite Calvert Hills structure (A) (Fitzgerald 1979). Fitzgerald (1979) documented its history since discovery. The Calvert Hills structure is a low-relief circular The Australian Museum retains the largest known mass of depression that is possibly an exhumed impact crater partly 42.29 kg. About 12.7 kg was apparently acquired by a Mr exposed in otherwise flat-lying rocks of the McArthur Basin (Figure 33). It was first identified by Peter Haines from aeromagnetic images, aerial photos and ASTER imagery. Aeromagnetic images show a circular magnetic low at 17°22’S 137°28’E, 4 km in diameter, disrupting the high frequency signature of the magnetic Gold Creek Volcanics. The structure was visited and documented by F Macdonald et al in 2003 (Macdonald and Mitchell 2004) who found that a partly exposed rim that borders the magnetic anomaly on the northern and eastern sides consists primarily of deformed late Palaeoproterozoic Masterson Sandstone

Figure 31. Tawallah Valley meteorite (© Australian Museum, Figure 32. Yenberrie iron meteorite sample USNM no 607 Hodge-Smith and Edwards 1941). (Buchwald 1975).

NTGS Record 2014-007 30 a b

Figure 33. Calvert Hills structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) Magnetics- radiometric overlay image (after NTGS GIWS). draped by flat-lying early Mesoproterozoic Karns Dolostone. between 500 m and 800 m. The central uplift probably They noted structural relationships such as radial and rebounded by 300 m to 400 m. circumferential folding consistent with an impact structure. The Gulpuliyul structure must be younger than the The partial remnants of a rim suggest a diameter somewhat youngest deformed target formation, the Dook Creek greater than that of the aeromagnetic anomaly, at about Formation of the Mount Rigg Group, which is assumed 5.5 km. The site was briefly described by Haines (2004, to be about 1600 Ma, based on regional correlations to 2005) and Macdonald and Mitchell (2004). The centre is dated formations. The structural disturbance is inferred to covered, so it is difficult to search for shocked lithologies. predate the Derim Derim Dolerite, emplaced at 1325 Ma, The structure is inferred to be late Palaeoproterozoic to because aeromagnetically detected dykes that are assumed earliest Mesoproterozoic age, bracketed by the ages of the to be of this intrusive suite cut the structure without Masterson Sandstone and Karns Dolostone. obvious disruption. Thus, the age of the purported impact is Mesoproterozoic, most likely between 1600 Ma and Gulpuliyul structure (B) 1500 Ma (Plumb 2005).

The structural anomaly later referred to as the Gulpuliyul Maningrida structure (C) structure, was first noticed in the field by Peter Haines and Ken Plumb in 1994 during combined NTGS and AGSO The Maningrida structure is an circular aeromagnetic mapping of MOUNT MARUMBA. However, it was only anomaly, 8 km in diameter, in the Arafura Basin off the during map compilation in 1995 that Plumb recognised northern coast of the NT, centred at 11°53’27S 134°12’44E. the circular nature of the feature and first considered an Although first listed by Haines (2004) as ‘Milingimbi’, this impact origin. It was noted as a probable impact structure was corrected to the more appropriate name Maningrida by by Sweet et al (1999). In the key reference, Plumb (2005) Haines (2005). On 1VD or otherwise enhanced imagery, described Gulpuliyul as an eroded circular to pentagonal it appears to have a demagnetised outer annulus and weak feature about 8.5 km across and centred at 13°19’S central magnetic high, with radial features as are typical of 134°06’E (Figure 34). impact structures (Figure 35). Highly deformed and brecciated strata of the Katherine There is a small island (Haul Round Island) near the River and Mount Rigg groups within the site contrast centre which may indicate a central uplift. The structure with the gently dipping strata outside. Strata within the has not been visited, but remotely sensed data, including structure are often at a lower structural level than the same satellite imagery, indicate chaotically folded and faulted unit outside, and are commonly overturned by southward- strata, mostly just below sea level surrounding the sandy directed thrusts and recumbent folds. Exposures display Haul Round Island. Such deformation is at odds with an overall concentric or tangential pattern. Although no the essentially flat-lying strata of the Arafura Basin that melt breccia, shatter cones or other definitive evidence of outcrop along the coast. These target rocks are probably shock metamorphism have been documented, no systematic Neoproterozoic or Cambrian in age and this is the only search has ever been undertaken because an impact origin constraint on the timing of the possible impact event was only suspected after the completion of fieldwork. The (Haines 2005). available geophysical data do not show any anomaly, but the data are probably too widely spaced. Renehan structure (D) Provided the impact hypothesis is correct, the impact trajectory would have been at a shallow angle from the The Renehan structure, centred at 18°18’45”S 132°39’55”E, north. The depth of the transient crater was probably is a circular aeromagnetic anomaly, 10 km in diameter,

31 NTGS Record 2014-007 identified by NTGS geophysicists and Haines (2004, sensed data, including satellite imagery (Figures 36a, b), 2005). The structure is mostly obscured by surficial suggests that this outcrop might be atypically chaotically cover and has not been visited. A small outcrop of older folded and faulted. The 1VD magnetic image (Figure 36c) and therefore uplifted Palaeoproterozoic Tomkinson shows features suggestive of a complex impact structure, Creek Group has been mapped near the centre. Remotely including a demagnetised outer annular zone and central a

134°04' 134°08' Mesoproterozoic b Mount Rigg Group Dook Creek Formation beneath Mesozoic and/or Cenozoic cover

13°17' Bone Creek Sandstone ? 50 undivided Bone Creek & Gundi sandstones beneath cover (and some Dook Creek Fm?)

? 65 Palaeoproterozoic Katherine River Group ? 10 Gundi Sandstone ? 20 beneath Mesozoic and/or Cenozoic cover McCaw Formation beneath Mesozoic and/or Cenozoic cover ? ? ? 10 Bonanza Creek Formation 10 Shadforth Sandstone 45 15 30 10 Cottee Formation 4 30 15 ? ? geological boundary 15 25 50 40 ? fault (approximate where dashed) ? 2 5 25 thrust fault 20 60 55 dyke - dolerite strike and dip of strata

35 35 strike and dip of overturned strata 35 75 4 70 40 45 minor folds 30 8 60 40 asymmetrical showing plunge 30 reclined anticline showing plunge and 70 40 reclined syncline dip of axial plane 35 13°21' 7 15 photo interpretation 15 horizontal strata 6 6 strata dipping <5° 6 10 40 strata dipping 5–15° 35 5 strata dipping 15–45° vertical strata 0 3 km overturned strata A14-174.ai Figure 34. Gulpuliyul structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) Geological sketch map (after Plumb 2005).

NTGS Record 2014-007 32 magnetic high with evidence of radial folds. Haines (2004, feature (Figure 36d) shows a near horizontal magnetic 2005) interpreted the feature as disrupting Kalkarindji body about 400 m above magnetic volcanic rocks. This Suite volcanic rocks in the sub-surface, which if correct, could be interpreted as an intrusion (sill), an impact melt would suggest that it must be younger than early Cambrian. sheet, or possible a remnant of volcanic rocks displaced A magnetic depth transect (see Clifton 2013) across this upwards around the outer part of a central uplift.

a b

Figure 35. Maningrida structure. (a) Haul Round Island and submerged outcrop off centre of the Maningrida structure (after Google earth, TerraMetrics, DigitalGlobe 2014). (b) Magnetic 1VD image (after NTGS GIWS).

a b

c d

Figure 36. Renehan structure. (a) Satellite image (after Google earth, CNES/Spot Image 2014). Box shows location of (b). (b) close-up of (a) showing chaotically folded and faulted Tomkinson Creek Group rocks. Location shown by box in (a) and (c). (c) Magnetic 1VD image (after NTGS GIWS 2014). Box shows location of (b). (d) East–west magnetic transect across Renehan Structure (image courtesy of Roger Clifton, NTGS). Near-horizontal signature of a magnetic body is approximately 400 m above magnetic signature of underlying basalt. Note that method used to generate cross-section results in horizontal exaggeration of width of feature.

33 NTGS Record 2014-007 Wessel structure (E) been previously discussed in the impact cratering literature. The Roman numeral after each name refers to the map The Wessel structure is a 2.5 km doughnut-shaped location, if known. aeromagnetic low at 20°36’40’E 135°04”45”S coincident with a topographic low in the Davenport Ranges Barramundi circular structure (I) (Figure 37a). It is most pronounced in the 1VD magnetic data (Figure 37b) and has been noted as a geophysical The Barramundi structure is a buried, semi-circular anomaly by Arafura Resources, and as a possible impact aeromagnetic anomaly, 4 km in diameter, at 16°49’S 136°40’E structure by Macdonald and Mitchell (2004), NTGS which is apparently a circular hole within a flat-lying magnetic and Arafura. As outcrop is extremely poor, and the pre- mafic igneous body (Figure 38). This makes it analogous existing structure of highly folded Proterozoic dolerites to the nearby Foelsche impact structure and Calvert Hills and siltstones is complex, the origin of the structure will structure. The Barramundi structure is entirely buried likely remain enigmatic until it is drilled (Macdonald and beneath Mesoproterozoic strata and its origin thus remains Mitchell 2004). Similarly, any possible relationship to the uncertain. It was listed by Haines and Rawlings (2002) as a Kurinelli Meteorites, from the nearby Kurinelli gold field to possible impact structure. If it is an impact structure, its age the southwest, would need further work. must be late Palaeoproterozoic to early Mesoproterozoic.

CIRCULAR STRUCTURES OF UNKNOWN AFFINITY Eurowie Creek circular structure (II)

This section lists circular structures of uncertain origin in A circular feature, less than 1 km in diameter, referred to the NT in alphabetical order. These are all features that have as the Eurowie Creek structure was mapped at 22°27’S

a b

Figure 37. Wessel structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) TMI 1VD overlay image (after NTGS GIWS 2014).

a b

Figure 38. Barramundi circular structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) TMI image (after NTGS GIWS 2014).

NTGS Record 2014-007 34 136°04’E in flat-lying Cambrian strata during the mapping concluded that the depression was not formed by erosion of the HUCKITTA geological map sheet by NTGS (Freeman but has an impact origin (Hamacher et al 2012). However et al 1986, Figure 39). It was listed as a possible impact site there is evidence that Puka is not an impact structure. For by Haines (2004) but its origin is uncertain. example a simple impact crater should show upturned deformed strata in the walls, and an overturned flap; Puka circular structure (III) the latter can be later eroded. In this case, there are flat- lying undeformed strata in the wall at Puka. In addition, The 280 m diameter Puka structure, located at 24°03’05.33”S there are many similar topographic features in the area 132°42’33.75”, was found by Duane Hamacher (Macquarie (for example at 24°4’35.03”S and at 132°45’12.69”E) that University) by following up a western Arrernte story of appear to be the result of erosion. Hamacher et al (2012) a star falling to Earth with a noise like thunder. In the acknowledged that the diagnostics required to identify it legend, the star fell into a spring-fed waterhole called Puka as of impact origin (such as meteorite fragments, shatter in Palm Valley, where the serpent Kulaia lived (Hamacher cones, ) are lacking. and Norris 2009). Hamacher identified a half-bowl-shaped It is “estimated” that the Puka impact is “millions of crater on Google Earth imagery (Figure 40). Subsequent years old” meaning that the Aborigines could not have ground investigations by a Macquarie University survey observed the actual impact, but would have had to deduce a team in 2009 noted no evidence of volcanism and meteoritic origin (Nerlich 2009).

a b

Figure 39. Eurowie Creek circular structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) Radiometric image (after NTGS GIWS 2014).

Figure 40. Puka circular structure (after Google earth, DigitalGlobe 2014).

35 NTGS Record 2014-007 Sheridan Creek circular structure (IV) geophysical signature and structural geology. P Haines and others visited this structure in 2000 and also examined drill The Sheridan Creek structure is a ring-like, positive core and thin sections, but found no unequivocal evidence aeromagnetic anomaly, 3 km in diameter, disrupting a of impact. The origin remains obscure. reversely magnetised magnetic dolerite sill at 13°04’10”S 135°06’01’E (Figure 41). The source of the anomaly is buried Spring Range circular structure (VI) beneath younger cover. It was noted by Haines (2004) as a possible impact structure because of some resemblance to the The Spring Range structure is a circular topographic aeromagnetic signature of known impact structures such as feature, 300 m in diameter, in flat-lying sandstone of Foelsche. The host rocks are of Mesoproterozoic age. the late Neoproterozoic Central Mount Stuart Formation of the Georgina Basin. It is located 57 km southeast of Spear Creek circular structure (V) Barrow Creek at 21°51’43”S 134°18’28”E. The structure is evident on aerial photos, although not clearly visible from Haines and Rawlings (2002) and Haines (2004) briefly the ground (Figure 44). It was documented as a possible documented a circular multi-ring topographic feature at eroded impact structure by Haines (1989), based on the Spear Creek superficially resembling an eroded central presence of planar microstructures in quartz in sandstone uplift of a complex crater centred on 17°16’37.5”S; blocks from within the structure. However, after re- 135°50’03”E (Figure 42). The structure is 800 m to 900 m examination of these microstructures, Haines (2005) in diameter. It has been geophysically surveyed, mapped in concluded that they are not of the type unambiguously detail and drilled by two exploration companies. This work diagnostic of impact. Thus the origin of the feature failed to locate an inferred central igneous diatreme but did remains undetermined. The maximum age constraint is provide some evidence of an impact origin (Dunster 2009a). provided by the late Neoproterozoic age of the target rocks An equidimensional magnetic low of 50 nT corresponds (Haines 2005). with the centre of the structure and the outer rim of the topographic feature is a relative magnetic high, creating ECONOMIC IMPLICATIONS an annular magnetic high with a magnetic low at its centre (Figure 42b). This could be interpreted as subsurface Meteorites and their impact structures have a number of cratering of the Helen Springs Volcanics. The surface value-related implications. They have scientific value, structure is mapped as a radially faulted series of concentric cultural significance and are important for tourism and ring folds with deformation increasing towards the centre education. Moreover, impact cratering is considered as (Figure 43). Locally pervasive brittle deformation has a potential driver of economic mineral formation. Single reduced the rock to long thin slivers and there is some large impacts and spatial and temporal impact clusters evidence of anomalous Ni and Ti. have been implicated as affecting crustal evolution and The Spear Creek structure may be evidence for an impact plate tectonics (Glikson and Vickers 2010) and therefore structure targeted on the Cambrian Top Springs Limestone driving or triggering volcanic activity, faulting, heat flow and affecting the underling early Cambrian Helen Springs and atypical sedimentation. Such processes are critical to Volcanics (Dunster 2009a). Being limestone exposed at the the formation of economically significant mineralisation. surface, there is also an overprint of solution collapse, but Impact structures themselves are viable exploration a sinkhole alone cannot explain its solitary occurrence, the targets for a range of commodities. Approximately 25%

a b

Figure 41. Sheridan Creek circular structure. (a) Satellite image (after Google earth, DigitalGlobe, CNES/Spot Image 2014). (b) TMI image (after NTGS GIWS 2014).

NTGS Record 2014-007 36 a

b Carpentaria Highway

0 100 km 800 mE 1000 mE 1200 mE Magnetic North 30

Stuart Highway Spear Creek

L Tablelands L

20 30

Highway 40

TENNANT H CREEK Barkly Highway H

nT 40 30

55–60 20 10

50–55 L H 45 SPC 3 50 50 45–50

40–45

35–40 contour interval: 5 nT contour values: add 49300 nT 30–35 sensor height: 3 m station spacing: 10 m 25–30 diurnal correction by continuous recording base

50 50 station at approx. 1075 mE 1025 mN 20–25 H grid established by topofil and compass 15–20 drillhole position (approx) 60

60 10–15 L

5–10

0–5 0 100 200 300400 m A09-179.ai

Figure 42. Spear Creek circular structure. (a) Satellite image (after Google earth, CNES/Spot Image 2014). (b) Magnetic profile (Colliver and Bubner 1987).

37 NTGS Record 2014-007 of all terrestrial impact craters world-wide have some resource potential of impact structures has been discussed resource affiliation, either as a direct result of the impact by Grieve and Masaitis (1994), Hawke (2004), Grieve event or through modification of the target rocks (Hawke (2005), Pirajno (2005), Reimold et al (2005) and Hawke and Dentith 2006); 18% are currently exploited or have and Dentith (2006). been exploited in the past (Hawke 2004). The total value of Impact-related resources can be classified as pro-, syn- impact-related resources in North America was estimated or epigenetic depending on the timing relative to impact. at US$18 billion per year in 2005 (Grieve 2005). The An impact can produce a resource in any of five ways:

a 135.824 ° 135.828 ° 135.832 ° 135.836 °135.84 °

AA Magnetic North True North

45 -17.272 °

24

46 22 22 48

DD86SC2B SPC3 SPC1 PD83SC2A DD835CI 8 -17.276 ° PD84SC2A 24 26 54

58 48 48

SCREE 48 SPC2 40

B 45 BARITE

28 ABUNDANT

SCREE

44 -17.28 ° 12 38 15 34 SCREE

35

0 100 200 300400 m A09-177.ai

ferricrete and pisolitic laterite siltstone and micaceous sandstone, variously disrupted, brecciated and ferruginised, minor lenses of limestone brecciated ironstone brecciated massive silicified brecciated to massive cavernous limestone coarse sandstone breccia with textures resembling tuff, abundant Helen Springs Volcanics cobbles and boulders and blocks of silicified (section only) brecciated sandstone, mostly recessive McArthur Group breccia and brecciated sandstone sedimentary rocks (section only) siltstone alluvium b 45° 22° 58° 48°45° bedding inclination as DD86SC2DD83SC1 PROJECTED PROJECTED measured at surface A SPC1 PROJECTEDfault B

cavernous limestone ? ? ? ? steeply dipping in part Helen Springs Volcanics 123 m A09-178.ai 150 m Figure 43. Spear Creek geology and cross section (after Colliver and Bubner 1987 and modified by Dunster 2009a).

NTGS Record 2014-007 38 • the impactor itself constitutes the resource in Canada, mineralised structures in Sweden, USA and (syngenetic) Estonia, and arguably some of the Zn-Cu-Pb deposits near • existing resources enhanced, preserved or exposed Sudbury that are believed to be crater-floor sedimentary by impact (progenetic) exhalative deposits formed as hot fluid was discharged long • existing resources enhanced by long-lived after impact. processes that were facilitated by the impact Impact related hydrothermal activity may also have had a (epigenetic) significant role in the formation of some epigenetic Cu-Ni-PGE • a new resource created by, and synchronous with Sudbury ore (Grieve 2005) as distinct from mineralisation impact (syngenetic) that was directly related to the igneous intrusion. • a new resource created by long-lived processes The most economically significant epigenetic impact- that were facilitated by the impact or its physical related resources are hydrocarbons. Eleven out of twenty- remnants (epigenetic). six impact structures in North American petroliferous basins are, or have been commercially exploited (Hawke Progenetic examples include the Vredefort Dome 2004). Impact can enhance or create reservoir porosity where the crater has preserved, and possibly enhanced the and permeability to the extent that even impact-fractured Witwatersrand gold field. Elsewhere, uranium and iron crystalline basement has been exploited as a hydrocarbon are made accessible for mining by the central uplift of reservoir. The structural deformation resulting from impact structures in Canada and the Ukraine. Arguably, some of can produce structural and stratigraphic traps, or even form these deposits were also enhanced by the impact. its own depositional basin. Depending on distance and The best known example of syngenetic mineralisation temperature, the residual thermal effects of an impact may associated with impact is Sudbury in Canada, which is accelerate maturation. possibly the largest single mineralising system on earth Hawke (2004) cited the Cameche Bay oil fields in the (Hawke 2004). Some early workers had argued that the Gulf of Mexico as being directly linked to the Chicxulub orebody itself was of extra-terrestrial origin. However, impact structure. At the Avak structure on the Barrow High the current consensus is that the impact resulted in the in Alaska, the impact was responsible for the deposition formation of the uniquely layered melt sheet known as the of the reservoir/seal couplet and for anomalous thermal Sudbury Igneous Complex, which in turn is responsible for maturity. An 820 m oil column is actually reservoired in the nickel-dominated mineralisation. an impact megabreccia at the Red Wing Creek structure Impact diamonds also fall into the syngenetic category. in the US Williston Basin. Potentially economic crater-fill These are generally only of poor industrial quality, but are deposits include oil shale in the Ukrainian Boltysch crater sometimes found in greater concentrations than in volcanic and industrial minerals from crater-fills in South Africa, pipes. Canada and Germany (Hawke 2004). Epigenetic metalliferous deposits commonly invoke Impact structures can also contain or affect regional fracture porosity and permeability, and hydrothermal ground water resources (Reimold et al 2005). convection cells analogous to those above igneous intrusions. Although Australia and the NT have an extensive Examples include sulfides in the 23 Ma Haughton structure impact history by world standards, there are no known

Figure 44. Spring Range circular structure (after Google earth, DigitalGlobe 2014).

39 NTGS Record 2014-007 economic resources unequivocally directly related to REFERENCES impact structures. Three possible relationships from outside the NT have been discussed by Piranjno (2005) and Hawke Alderman AR, 1932. The meteorite craters at Henbury, (2004). Many of the NT impact structures are considered too central Australia with addendum by LJ Spencer. small or too deeply eroded to warrant mineral exploration. Mineralogical Magazine 23, 19–32. Gosses Bluff is the only confirmed impact structure to have Anonymous, 1932. Sun walk fire devil rock. The Mail, knowingly been explored for its resource potential. The 19 November 1932. centre of the crater has been tested by two petroleum wells, Astronomical Research Network, 2006. Eagles Nest BRA. Gosses Bluff-1 and -2; however the lack of an effective seal Astronomical Research Network website , unlikely to have been retained. Peak oil generation, and [accessed June 2014]. presumably migration, in the Amadeus Basin preceded Astronomical Research Network, 2014. Roper River IIIAB. impact by 60 million years and secondary migration would Astronomical Research Network website , in shallow holes drilled during seismic recording indicate [accessed June 2014]. that there may be still some potential on the periphery of the Axon HJ, 1968. The metallographic structure of the structure (Dunster 2009b). Dunster (2009a) described the iron meteorites Arltunga, Kopjes Vlei, Murnpeowie, possible relationships between base metal mineralisation at Braunau and Rancho de la Pila. Mineralogical the Spear Creek structure and its probable impact origin. Magazine 36/248, 1139–1142. give false impressions in geochemical surveys for mineral [accessed June 2014]. exploration. Impact products, such as diamonds, might also Baker G and Edwards AB, 1941. The Bond Springs stony be misleading. Furthermore, some NT exploration targets meteorite. Memoirs of Museum Victoria 12, 49–58. such as diamond pipes (eg Merlin) or Redbank-style base Barringer DM, 1906. The geology of Coon Butte, Arizona, metals mineralisation in vertical breccia pipes involve and the Canyon Diablo meteorites. American Journal searching for topographic, geological or geophysically of Science 4/21, 402–403. circular features. Small impact structures in the same Bevan AWR, 1996. Australian crater-forming meteorites. geological provinces could prove misleading. AGSO Journal of Australian Geology and Geophysics 16, 421–429. LEGAL ISSUES REGARDING METEORITES Brett R, Guppy DJ and Milton DJ, 1970. Two circular structures of impact origin in Northern Territory, Meteorites found in the NT after 15 June 1988 are the property Australia. Meteoritics 5, 184. of the Crown and are protected under the Meteorites Act, as Brown PL, 1975. , Meteorites and Men. The amended in 2013, which is administered by the MAGNT. Scientific Book Club, London. Fossicking for meteorites is not permitted under the Buchwald VF, 1975. Handbook of iron meteorites. Meteorites Act 1988, and any meteorites found must, by University of California Press, Los Angeles. law, be passed on to MAGNT in the shortest practical time. Burke JG, 1986. Cosmic Debris: Meteorites in History. However, it is recognised that there is a long-established University of California Press. trade and popular interest in NT meteorites, mostly involving Carson CJ, 2010. The Victoria and Birrindudu basins: a Henbury, innumerable fragments of which were lawfully U-Pb SHRIMP study and review of resource potential: collected prior to 1988. Lawfully collected fragments may in ‘Annual Geoscience Exploration Seminar (AGES) be freely traded and/or exported from the NT, though their 2010. Record of Abstracts’. Northern Territory export overseas from Australia requires a permit under the Geological Survey, Record 2010-002. Commonwealth Movable Cultural Heritage Act. All other Carson CJ, 2013. The Victoria and Birrindudu meteorites, or suspected meteorites, found since 1988 must be Basins, Victoria River region, Northern Territory, offered to the MAGNT in the first instance (Megirian 1998). Australia: a SHRIMP U–Pb detrital zircon and Sm–Nd study. Australian Journal of Earth ACKNOWLEDGEMENTS Sciences 60, 175–196. Carson LJ, Haines PW, Brakel A, Pietsch BA and Ferenczi The authors wish to acknowledge and thank the following PA, 1999. Millingimbi, Northern Territory.1:250 000 people for their contribution to this publication: the late geological map series explanatory notes, SD53‑2. Ian Sweet for the use of his photographs and discussion Northern Territory Geological Survey, Darwin. on impact structures; Kelvin Hussey and John Goulevitch Carter NL, 1965. Basal quartz deformation lamellae – (Arafura Resources) for elaborating on the story of the a criterion for recognition of impactites. American Kurinelli meteorites, the late Dirk Megirian (MAGNT); Journal of Science 263, 786–806. and Duane Hamacher (Macquarie University) for providing Cassidy WA, 1968. Descriptions and topographic then-unpublished material on the Puka impact structure. maps of the Wolf Creek and Boxhole craters, PW Haines publishes with the permission of the Director of Australia (abstract): in French BM and Short the Geological Survey of Western Australia. Kathy Johnston NM (editors) ‘Shock Metamorphism of Natural and Greg MacDonald (NTGS) prepared the figures and Materials’, Mono Book Corporation, Baltimore, Kathy Johnston formatted the manuscript. MD, 623.

NTGS Record 2014-007 40 Clifton R, 2013. Magnetic depths to basalts – extension of Grieve RAF, 2005. Economic natural resource deposits Spector Grant method. ASEG Extended Abstracts 2013: at terrestrial impact structures. Geological Society, 23rd Geophysical Conference. [accessed July 2014]. Grieve RAF and Masaitis VL, 1994. The economic potential Colliver IC and Bubner GJ, 1987. Spear Creek MCs N of terrestrial impact craters. American Geological 980–983, final report for period ending 18 November Institute, International Geology Review 36, 105–151. 1986. Northern Territory Geological Survey Open File Grossman JN, 2000. The Meteoritical Bulletin, 94, Company Report CR1987‑0002. 2000 August. Meteoritics and Planetary Science 35, Corbett DWP, 1968. Catalogue of meteorites in the South A199 – A225. South Australian Museum 15, 767–790. [accessed June 2014]. Crook KAW and Cook PJ, 1966. Gosses Bluff – diapir, Guppy D J, Brett R and Milton DJ. 1971. Liverpool and crypovolcanic-volcanic structure or astrobleme? Strangways craters, Northern Territory: Two structures Journal of the Geological Society of Australia 13/2, of probable impact origin. Journal of Geophysical 495–516, pl 11–14. Research, 76, 5387–5393. De Laeter JR, 1973. Discrediting of the Hart Range, Haines PW, 1989. Probable impact structure near Barrow Australia, iron meteorite. Journal of the Royal Society Creek, Northern Territory, Australia. Australian Journal of Western Australia 56, 123–128. of Earth Sciences 36, 135–137. Dietz RS, 1947. Meteorite impact suggested by the Haines PW, 1996. Goyder impact structure, Arnhem orientation of shatter cones at the Kentland, Indiana, Land, Northern Territory. AGSO Journal of Australian disturbance. Science 104, 42–43. Geology and Geophysics, 16, 561–566. Dietz RS, 1967. Shatter Cone Orientation at Gosses Bluff Haines PW, 2004. Impact structures, possible impact Astrobleme. Nature 216 (5120), 1082–1084. structures, and circular features of uncertain origin in the Dunn PR, 1963. Hodgson Downs, Northern Territory Northern Territory. In possession of PW Haines, Perth. 1:250 000 geological series map and explanatory notes, Haines PW, 2005. Impact cratering and distal ejecta: the SD53‑14. Bureau of Mineral Resources, Australia. Australian record. Australian Journal of Earth Sciences Dunster JN, 2009a. Exploration history and interpretation 52, 481–507. of the Spear Creek structure, Walhallow. Northern Haines PW, 2007. Geophysical detection of eroded and Territory Geological Survey Open File Company buried impact structures in layered sedimentary and Report CR2009‑0068. sedimentary-igneous terrains: Foelsche impact structure Dunster JN, 2009b. Shallow gas occurrences in NT. NTGS and relatives, Australia. Abstract U22A-06. American Technical note 2009‑001 (updated 14/02/2011). Geophysical Union, Fall Meeting 2007. Edgoose CJ and Haines PW, 2012. Geology of the Amadeus Haines PW and Rawlings DJ, 2002. The Foelsche structure, Basin, central Australia. Field guide NT-1. 11–16 Northern Territory, Australia: an impact crater of August 2012. 34th International Geological Congress. probable Neoproterozoic age. Meteoritics & Planetary Northern Territory Geological Survey, Technical Note Science 37, 269–280. 2012‑001. Haines PW, Rawlings DJ, Sweet IP, Pietsch BA, Plumb Edwards AB, 1943. A note on the micro-texture of the KA, Madigan TLA and Krassay AA, 1999. Blue Mud Arltunga meteorite. Records of the Australian Museum Bay, Northern Territory. 1:250 000 geological map 21, 154–155. series explanatory notes, SD 53‑7. Northern Territory Fectay B and Bidaut C, 2014. Meteorite.fr - All about Geological Survey and Australian Geological Survey Meteorites. Meteorite fr website , [accessed June 2014]. Haines PW, Sweet IP and Mitchell K, 2008. The Cleanskin Fitzgerald MJ, 1979. The chemistry and mineralogy of structure: a preliminary report on a large impact meteorites from South Australia and adjacent regions. structure in the Mesoproterozoic South Nicholson PhD thesis. Department of Geology and Mineralogy, Group, northern Australia. Geological Society of University of Adelaide. Australia Abstracts 89, 127. Glikson AY and Vicker J, 2010. Asteroid impact connections Haines PW, Sweet IP and Mitchell K, 2012. Cleanskin of crustal evolution. Australian Journal of Earth structure, Northern Territory and Queensland, Sciences 57, 79–95. Australia: evidence for an impact origin. Abstract 5176. Grady M, Hutchinson R and Graham AL, 2000. Catalogue 75th Annual Meteoritical Society Meeting. in the collection of the Natural History Museum, [accessed June 2014]. London, 5th edition. Cambridge University Press. Hamacher DW and Norris RP, 2009. Australian Aboriginal Graham AL, 1978. Discovery of the Rabbit Flat, Australia, Geomythology: Eyewitness Accounts of Cosmic stony meteorite. Meteoritical Bulletin 55 (13), 345–346. Impacts? Archaeoastronomy: the Journal of Astronomy Graham AL, Bevan AWR and Hutchison R, 1985. and Culture 22, 62–95. Catalogue of meteorites (with special reference to those Hamacher DW, Buchel A, O’Neill C and Britton TR, 2012. represented in the collection of the British Museum An impact crater in Palm Valley, Central Australia? (Natural History), 4th edition. BMNH and University of Proceedings of the 11th annual Australian Space Arizona Press. Sciences Conference, 26–29 September 2011, Canberra,

41 NTGS Record 2014-007 12p. [accessed Madigan CT, 1937. The Boxhole crater and the Huckitta June 2014]. meteorite (central Australia). Royal Society South Hamacher DW, O’Neill C, Buchel A and Britton TR, Australia Transactions and Proceedings 61, 187–190. 2010. Evidence for a putative impact structure in Palm Madigan CT, 1940. The Boxhole meteoritic iron, Central Valley, central Australia. Abstract 5043. 73rd Annual Australia. Mineralogical Magazine 25 (168), 481–486. Meteoritical Society Meeting. [accessed June meteorite, Central Australia. Mineralogical Magazine 2014]. 25 (165), 353–371. Hawke PJ, 2003. Some ring-like magnetic anomalies in Mawson D, 1934. The Arltunga and Karoonda meteorites. impact structures and their possible causes. Abstract Transactions of the Royal Society of South Australia 58, 4064. Third International conference on large meteorite 1–6, with plates. impacts, August 5–7, 2003. Nördlingen, Germany. [accessed June 2014]. Reviews 92, 99–116. Hawke PJ, 2004. The geophysical signatures and McColl D, 1990. Distribution and sculpturing of iron exploration potential of Australia’s meteorite impact meteorites from the major craters at Henbury (abstract). structures. PhD thesis, University of Western Australia, Meteoritics, 25, 384. School of Earth and Geographical Sciences. McIntyre DB, 1962. Impact metamorphism at Clearwater Hawke PJ and Dentith MC, 2006. The exploration potential lake, Quebec. Journal of Geophysical Research 67, of Australia’s meteorite impact craters. ASEG extended 1647. abstracts 2006 (1). Megirian D, 1998. Report on the ‘Kurinelli Meteorite’, Hill, AC, Haines PW, Grey K & Willman S, 2008. New Northern Territory, with reference to the Meteorites Act records of Edicaran Acraman ejecta in drillholes from 1988. MAGNT Research Report No. 2, September 1998. the Stuart Shelf and Officer Basin, South Australia. [accessed June 2014]. Hodge P W, 1965. The Henbury meteorite craters. Megirian D, Freeman MJ and Wyche S, 1987. A re- Smithsonian Contributions, Astrophysics 8, 199–201. investigation of the find-site of the Huckitta Meteorite Hodge P W and Wright FW, 1971. Meteoritic particles in the from central Australia. The Beagle 4 (1), 133–138. soil surrounding the Henbury meteorite craters. Journal Meteoritical Society (International Society for Meteoritics of Geophysical Research 76, 3880–3895. and Planetary Science), 2014. Meteoritical Bulletin Hodge-Smith T and Edwards AB, 1941. The Tawallah Database. valley meteorite. Records of the Australian Museum [accessed June 2014]. 21, 1–8. [accessed June meteorite craters, Northern Territory, Australia. 2014]. US Geological Survey Professional Paper 599-C, Hutchison R, Bevan AWR and Hall JM, 1977. Appendix C1 – C17. to the Catalogue of Meteorites with special reference Milton JD, Barlow BC, Brett R, Brown AR, Glikson AY, to those represented in the collection of the British Manwaring EA, Moss FJ, Sedmik ECE, Van Son J Museum (Natural History). Publication 789 of the and Young GA, 1972. Gosses Bluff impact structure, British Museum. Whitefriars Press, London, England. Australia. Science 175 (4027), 1199–1207. Kenkmann T and Poelchau MH, 2008. Matt Wilson: an Milton DJ, Barlow BC, Brown AR, Moss FJ, Manwaring elliptical impact crater in Northern Territory, Australia. EA, Sedmik ECE, Young GA and Van Son J, 1996a. Abstract 1027. 39th Lunar and Planetary Science Gosses Bluff – a latest Jurassic impact structure, central Conference, March 10–14, 2008, League City, Texas. Australia. Part 2: seismic, magnetic and gravity studies. [accessed June 2014]. 16 (40), 487–527. Kenkmann T and Poelchau MH, 2009, Low-angle collision Milton DJ, Glikson AY and Brett R, 1996b. Gosses Bluff with Earth: the elliptical impact crater Matt Wilson, – a latest Jurassic impact structure, central Australia. Northern Territory, Australia. Geology 37, 459–462. Part 1: geological structure, stratigraphy, and origin. Kohman TP and Geol PS, 1963. Terrestrial ages of AGSO Journal of Australian Geology and Geophysics meteorites from cosmogenic c14: in ‘Radioactive 16 (40), 453–486. Dating’. International Atomic Energy Agency, Vienna, Morgan JW and Wandless GA, 1983. Strangways Crater, 395– 411. Northern Territory, Australia: siderophile element Macdonald FA and Mitchell K 2004. New possible, probable, enrichment and lithophile element fractionation. and proven impact sites in Australia. Geological Society Journal of Geophysical Research 88B (supplement 2), of Australia Abstracts 73, 239. Australian Geological A819–A829. Conference, Hobart, Tasmania. Mountford CP, 1976. Nomads of the Australian Desert. Macdonald FA, Mitchell K and Stewart J. 2005. Amelia Rigby Ltd, Adelaide. Creek: a Proterozoic impact structure in the Davenport Mulvaney J, Morphy H and Petch A, 1997. ‘My Dear Ranges, Northern Territory. Australian Journal of Earth Spencer’ the letters of FJ Gillen to Baldwin Spencer. Sciences 52 (4/5), 631–640. Hyland House Melbourne.

NTGS Record 2014-007 42 Museum Victoria, 2014a. Gove Iron Octahedrite 111AB Scott ERD, Wasson JT and Buchwald VF, 1973. The chemical Australia Found in the Nabalco Bauxite Mine, near classification of iron meteorites. VII. A re-investigation Gove. Museum Victoria website [accessed June 2014]. Shoemaker CS and Macdonald FA, 2005. The Shoemaker Museum Victoria, 2014b. Gove Iron Octahedrite Na Australia legacy to the Australian impact record. Australian Found in the Nabalco Bauxite Mine, near Gove. Museum Journal of Earth Sciences 52, 477–479. Victoria website [accessed June 2014]. AGSO Journal of Australian Geology and Geophysics 16 Northern Territory Geological Survey, 1991. Astrogeological (4), 379–398. features of central Australia. Northern Territory Shoemaker EM and Shoemaker CS, 1997. Notes on Department of Mines and Energy pamphlet. the geology of Liverpool crater, Northern Territory, Nerlich S, 2009. Dreamtime meteor impact found with Australia. Abstract 1662. 28th Lunar and Planetary Google Earth. Universe Today website

found-with-google-earth-2/> [accessed June 2014]. 1988. The Boxhole Meteorite Crater, Northern Territory, Parks and Wildlife Commission of the Northern Territory, Australia. Abstract 1548. 19th Lunar and Planetary 2002. Henbury Meterorites Conservation Reserve, Science Conference, March 14–18, 1988, Houston, Draft Plan of Management, November 2002. Texas. [accessed June 2014]. pdf_file/0010/3160/henbury_pom.pdf> [accessed June Shoemaker EM, Macdonald FA and Shoemaker CS, 2014]. 2005. Geology of five small Australian impact craters. Parks and Wildlife Commission of the Northern Territory, Australian Journal of Earth Sciences 52, 529–544. 2014. Tnorala (Gosse Bluff) Conservation Reserve. Simmons K (editor), 1974. Boxhole Meteorite Crater and [accessed June 2014]. Australia. Meteor News, 23, 1–2, Jacksonville, Florida. Pirajno F, 2005. Hydrothermal processes associated with SpaceRef Interactive Inc, 2009. NASA ISS On-Orbit Status meteorite impact structures: evidence from three Australian 20 February 2009. SpaceRef website [accessed Australian Journal of Earth Sciences 52, 587–605. June 2014]. Planetary and Space Science Centre (PASSC), 2009. Earth Spencer LJ, 1932. A new pallasite from Alice Springs, impact database. Planetary and Space Science Centre, Central Australia. Mineralogical Magazine 23, 38 – 42. University of New Brunswick website [accessed Volume_23/23-136-38.pdf> [accessed June 2014]. June 2014]. Spray JG, Kelley SP and Dense MR. 1999a. Geology and Plescia JB, 2006. Kelly West Impact Structure, Australia, 40Ar/39Ar laser fusion dating of the Strangways Impact Gravity. Abstract 1259. 37th Lunar and Planetary Structure, Northern Territory, Australia. Abstract 1821. Science Conference, March 13–17, 2006, Houston, 30th Lunar and Planetary Science Conference, March Texas. [accessed June 2014]. meetings/LPSC99/pdf/1821.pdf> [accessed June 2014]. Plumb K, 2005. Gulpuliyul structure: a possible impact Spray JG, Kelley SP and Dense MR. 1999b. The structure of Mesoproterozoic age in western Arnhem Strangways impact structure, Northern Territory, Land, Northern Territory. Australian Journal of Earth Australia; geological setting and laser probe 40Ar/ 39Ar Sciences 52, 665–673. geochronology. Earth and Planetary Science Letters Poelchau MH and Kenkmann T, 2008. Matt Wilson, Australia: 172, 199–211. structural insights on elliptical crater formation. Abstract Sweet IP, Brakel AT, Rawlings DJ, Haines PW, Plumb KA 311, 86th Annual Meeting of the German Mineralogical and Wygralak AS, 1999. Mount Marumba, Northern Society – DMG, 14–17 September 2008, Berlin. explanatory notes SD53-6. Australian Geological [accessed June 2014]. Survey Organisation and Northern territory Geological Poelchau MH and Kenkmann T, 2011. Feather features: Survey (National Geoscience Mapping Accord). A low-shock-pressure indicator in quartz. Journal of Sweet IP, Haines PW and Mitchell K, 2005. Matt Wilson Geophysical Research 116, B02201–B02201. structure: record of an impact event of possible Early Reimold WU, Keoberl C, Gibson RL and Dressler BO, Mesoproterozoic age, Northern Territory. Australian 2005. Economic mineral deposits in impact structures: Journal of Earth Sciences 52, 675–688. a review: in Koeberl C and Henkel H (editors) ‘Impact Sweet IP, Haines PW and Mitchell K, 2008. The Cleanskin Tectonics’. Springer, Berlin, Germany, 479–552. Structure: a preliminary report on a large impact Rix P, 1965. Milingimbi, Northern Territory. 1:250 000 structure in the Mesoproterozoic South Nicholson Geological map series explanatory notes SD53-2. Group, northern Australia. Geological Society of Bureau of Mineral Resources, Canberra. Australia Poster.

43 NTGS Record 2014-007 Taylor SR and McLennan SM, 1979. Chemical relationships Werner E, 1904. Das Ries in der schwäbisch-fränkischen, among irghizites, zhamanshinites, Australasian Alb. Blatter des schwäbischen Albvereins 16, 153–167. tektites and Henbury impact glasses. Geochimica et Wlotzka F, 1994. The Meteoritical Bulletin 77, 1994 Cosmochimica Acta 43, 1551–1565. November. Meteoritics 29, 891–897. Tonkin P, 1973. Discovery of shatter cones at Kelly West Zummersprekel H, 2002. Fernerkundungs- und GIS- near Tennant Creek, Northern Territory, Australia. Analyse der Impaktstrukturen Strangways (N.T.) und Journal of the Geological Society of Australia 20, Shoemaker (W.A.), Australien. [Remote Sensing and 99 – 102. GIS analysis of the Strangways and Shoemaker Impact Wasson JT and Choi BG, 2003. Main-group pallasites Structures, Australia]. PhD Thesis, Department of – chemical composition, relationship to IIIAB irons Geosciences of Mathematics and Natural Sciences, and origin. Geochimica et Cosmochimica Acta 67, University of Munster (Westfälische Wilhelms- 3079 – 3096. Universität). Wasson JT and Kimberlin J, 1967. The chemical Zummersprekel H and Bischoff L, 2005. Remote sensing classification of iron meteorites – II irons and pallasite and geographic information system analyses of the with germanium concentration between 8 and 100 ppm. Strangways impact structure, Northern Territory. Geochimica et Cosmochimica Acta 31, 2065–2093. Australian Journal of Earth Sciences 52, 621–630.

NTGS Record 2014-007 44 APPENDIX 1. LIST OF METEORITE AND IMPACT STRUCTURES OF THE NT

Officially Map Impact criteria Meteorite Year of Name Location recognised location Mass Time of impact type Crater Geological Geophysical Shatter Impact Melt Impact micro discovery meteorite ref # diameter evidence evidence cones breccia breccia textures Known meteorite and impact structures

1 Alikatnima meteorite 23°20’S 134°07’E  1 Iron-ung 20 kg na N N N N N N 1931 not known 2 Amelia Creek impact structure 20°50’06”S 134°53’01”E – 2 na na 16 km Y ?M Y Y N Y 2002 1640 - 600 Ma 3 Arltunga meteorite 23°28’S 134°40’E  3 IID-an 18.1 kg ?metres Y N N N N N 1908 1907 or 1908 4 Basedow Range meteorite 25°06’S 132°33’E – IIIAB ?2 kg na N N N N N N <1957 = Henbury 4 5 Bond Springs meteorite 23°30’S 133° 50’E  5 H6 6.2 g na N N N N N N 1898 not known 6 Boxhole craters and meteorites 22°36’46’’S 135°11’43’’E  6 IIIAB 500 kg 180 m Y N N N N N 1937 30 ka 7 Burt Plain meteorite 23°33’S 133°52’E – 7 na 1.08 kg na N N N N N N 1932 not known 8 Cleanskin impact structure 18°09’15”S 137°56’21”E – 8 na na 15 km Y ? Y Y N Y 2007 between 1400 Ma and Early Cambrian Eagles Nest not recorded ?brachinite 154 g

9 Erldunda meteorite 25°17’47.3”S 133°12’00.2”E  9 H5 190 g na N N N N N N 1992 not known 10 Foelsche impact structure 16°39’57”S 136°46’59”E – 10 na na 6 km Y M ?Y Y N Y 2002 Mesoproterozoic Gallipoli Station No. 1 not recorded ?IIIAB 11 Gallipoli Station No. 2 meteorite 18°58’22”S 137°30’20”E  11 IVB 81 kg na N N N N N N 2001 not known 12 Glen Helen meteorite 23°41’S 132°40’E – Iron 727 g na N N N N N N <1963 ?= Henbury 12 13 Gosses Bluff impact structure 23°49’07”S 132°18’26”E – 13 na na >10 km Y MGS Y Y Y Y 1966-67 142.5 ± 0.8 Ma 14 Gove meteorite 12°10’48”S 136°46’12”E – 14 Na 304 g na N N N N N N not known not known 15 Goyder meteorite 13°28’30”S 135°02’30”E – 15 na na 3 km Y ? Y Y N Y 1996 <1325 Ma 16 Hart Range meteorite 23°S 131°E – ?III 608 g na N N N N N N not known = Boxhole 16 17 Henbury craters and meteorites 24°34’20”S 133°08’54”E  17 IIIAB ?2 MT 6-180 m Y N N N N N 1931 4200 ± 1900 a Pallasite- 18 Huckitta meteorite 22°17’14.5’S 135 °45’16.3”E  ?2.3 MT <2 m Y N N N N N 1939 na 18 Main gr 19 Kelly West impact structure 19°55’46”S 133°57’05”E – na na 8-20 km Y MG Y Y N N 1973 >550 Ma 19 20 Kurinelli meteorites 20°37’S 135°03’E – 20 octahedrite <1t na N N N N N N 1996 not known 21 Liverpool impact crater 12°23’46”S 134°02’50”E – 21 na na 1.6 km Y ?N ?N Y N ?N 1965 150 ± 70 Ma 22 Matt Wilson impact structure 15°29’36”S 131°11’23”E – 22 na na 6.3x7.5 km Y M ?Y Y N Y 2003 Mesoproterozoic 23 Mount Sir Charles meteorite 23°50’S 134°02’E  23 IVA 22.9 kg na N N N N N N 1942 not known Nutwood Downs meteorite not recorded – IIIAB >117 g na N N N N N N <1971 not known

24 Poeppel Corner meteorite 25°47’S 137°56’E  24 L6 277 g na N N N N N N 1980 not known 25 Rabbit Flat meteorite 20°22’S 130°07’E  25 H6 295 g na N N N N N N 1974 not known 26 Roper River meteorite ? 15°S 135°E  26 IIIAB 6.4 kg na N N N N N N <1927? not known 27 Strangways impact structure 15°12’S 133°34’E – 27 na na 16 km Y N Y Y Y ?Y 1971 646 ± 42 Ma 28 Tawallah Valley meteorite 15°42’S 135°40’E  28 IVB 75.75 kg na N N N N N N 1939 not known 29 Yenberrie meteorite 14°15’S 132°01’E  29 IAB-MG 132 kg na N N N N N N 1918 not known Possible impact structures

A Calvert Hills structure 17°22’S 137°28’E – A na na 4 km Y Y N N N N 2003 late Palaeo- to early Mesoproterozoic B Gulpuliyul structure 13°19’S 134 °06’E – B na na 8.5 km Y N N N N N 1999 Mesoproterozoic C Maningrida structure 11°53’27S 134°12’44E – C na na 8 km Y Y N N N N 2004 post ?Cambrian

E Renehan structure 18°18’45”S 132°39’55”E – D na na 10 km Y Y N N N N 2004 post Early Cambrian F Wessel structure 20°36’S 135°05’E – E na na 2.5 km ?Y Y N N N N 2003 not known Circular features of unknown affinity

I Barramundi structure 16°49’ S 136°40’ E – I na na 4 km ?Y Y N N N N 2001 Late Palaeo- to early Mesoproterozoic

II Eurowie Creek structure 22° 27’ S 136° 04’ E – II na na <1 km ?Y N N N N N 2004 post Cambrian III Puka structure 24°03’05.33”S 132°42’33.75” – III IV Sheridan Creek structure 13°04’10”S 135°06’01”E – IV na na 3 km N Y N N N N 2004 post Mesoproterozoic V Spear Creek structure 17°16’37.5”S 135°50’03”E – V na na 800 m Y Y N N N N 2002 post Early Cambrian VI Spring Range structure 21°51’43”S 134°18’28” E – VI na na 300 m Y N N N N ?N 1989 post Late Neoproterozoic Y=present, N=not recorded, M=magnetic data, G=gravity data, S=seismic data Table A1. List of meteorite and impact structures of the NT. 45 NTGS Record 2014-007 APPENDIX 2. METEORITE CLASSIFICATION SYSTEM

Table A2. Stony meteorites - chrondrites Distinguishing features / Letter designation NT example Composition type chondrule character abundant E3, EH3, EL3 distinct E4, EH4, EL4 Enstatite Chondrites less distinct E5, EH5, EL5 indistinct E6, EH6, EL6 melted E7 abundant H3-H3.9 distinct H4 H Chrondrites less distinct H5 Erldunda indistinct H6 Bond Springs, Rabbit Flat melted H7 abundant L3-L3.9 distinct L4 Ordinary LChrondrites less distinct L5 Chrondrites indistinct L6 Poppel Corner melted L7 abundant LL3-LL3.9 distinct LL4 LL Chondrites less distinct LL5 indistinct LL6 melted LL7 I - Ivuna phyllosilicates, magnetite, friable, CI more water M- Mighei phyllosilicates, tochilinite,olivine, CM1-CM2 friable, less water V - Vigarano Fe rich olivine, CAIs CV2-CV3.3 Carbonaceous R- Renazzo phyllosilicates, pyroxene, olivine, CR Chondrites metal O- Omans olivine, pyroxene, CAIs, metal CO3-CO3.7 K - Karoonda olivine, CAIs CK B- Bencubbin metal, pyroxene CB H (refers to high iron CH alteration) Kakangari-type K Rumurutiites R (after Fectay and Bidaut 2014)

Table A3. Stony-iron meteorites Distinguishing Features Letter NT Example Composition Type / Chondrule Character Designation Main group pallasites iron, olivine, pyroxene Pallasites Eagle Staion grouplet iron, olivine, pyroxene PAL Huckitta Pyroxene palasite grouplet iron, pyroxene 1A iron, Ca pyroxene, 2A Class (basaltic) plagioclase 3A 4A MES 1B iron, Ca pyroxene, Class B (ultramafic) 2B plagiclase, orthopyroxene 3B Class C (orthopyroxene) orthopyroxene 2C (after Fectay and Bidaut 2014)

NTGS Record 2014-007 46 Table A4. Iron meteorites - structural classification Widmanstatten band width Structural class >50 mm H Octahedrites coarsest 3.3-50 mm Ogg coarse 1.3-3.3 mm Og medium 0.5-1.3 mm Om fine 0.2-0.5 mm Of finest 0.2 mm Off plessitic 0.2 mm kamacite spindles Opl (no structure) D (after Fectay and Bidaut 2014)

Table A5. Iron meteorites - chemical classification Magnetic character Minerals Structural class Letter designation NT example kamacite, taenite, silicates, non-magnetic Om-Og IAB Yenberrie carbides kamacite, taenite, silicates, magnetic Om-Og IC carbides kamacite, taenite, silicates, magnetic Ogg, H IIAB (daubreelite) magnetic kamacite, aentite Ogg, H IIC magnetic kamacite, taenite Of, OM IID Arltunga non-magnetic kamacite, taenite, silicates Off-Og IIE magnetic kamacite, taenite Plessitic octahedrite, Atax IIF magnetic IIG kamacite, taenite, troilite, Boxhole, Henbury, Roper magnetic Om-Og IIIAB phosphides River non-magnetic kamacite, taenite, carbides Off-D IIICD kamacite, taenite, carbides, magnetic Og IIIE graphite magnetic kamacite, taenite Om-Og IIIF magnetic kamacite, taenite Of IVA Mount Sir Charles magnetic kamacite, taenite D IVB Gallipoli, Tawallah Valley kamacite, taenite, silicates, magnetic all ungrouped irons graphite Green font = NT examples (after Fectay and Bidaut 2014)

The following meteorite types have been identified in the NT (indicated by red font in table): • chondrites • H5 • H6 • L6 • stony irons • PAL • iron meteorites • IAB • IID • IIIAB • I VA • IVB • Ungrouped irons

47 NTGS Record 2014-007 THIS PAGE LEFT INTENTIONALLY BLANK

NTGS Record 2014-007 48