euroli 1 borehole completion record · 2018. 5. 14. · euroli 1 borehole completion record...

Record 2018/10 | eCat 117102Geological Survey of New South Wales Record GS2018/0200

Euroli 1 borehole completion recordSouthern Thomson Project

I. C. Roach, K. F. Bull, M. Drummond, C. B. Folkes, P. Gilmore, R. Hegarty, S. L. Jones and D. B. Tilley.

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Euroli 1 borehole completion record

Southern Thomson Project

GEOSCIENCE AUSTRALIA RECORD 2018/10 GEOLOGICAL SURVEY OF NEW SOUTH WALES RECORD GS2018/0200

I. C. Roach1, K. F. Bull2, M. Drummond2, C. B. Folkes2, P. Gilmore2, R. Hegarty3, S. L. Jones1 and D. B. Tilley2

1. Geoscience Australia. 2. Geological Survey of New South Wales. 3. Formerly Geological Survey of New South Wales

Department of Industry, Innovation and Science Minister for Resources and Northern Australia: Senator the Hon Matthew Canavan MP Secretary: Dr Heather Smith PSM

Geoscience Australia Chief Executive Officer: Dr James Johnson

Department of Planning and Environment, New South Wales Minister: The Hon Don Harwin MLC Secretary: Ms Carolyn McNally

Geological Survey of New South Wales Executive Director: Dr Chris Yeats

This paper is published with the permission of the CEO, Geoscience Australia and the Executive Director, Geological Survey of New South Wales.

© Commonwealth of Australia (Geoscience Australia) and State of New South Wales (Geological Survey of New South Wales) 2018.

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ISSN 2201-702X (PDF) ISBN 978-1-925297-80-5 (PDF) eCat 117102

Bibliographic reference: Roach, I. C., Bull, K. F., Drummond, M., Folkes, C. B., Gilmore, P., Hegarty, R. Jones, S. L., Tilley, D. B. 2018. Euroli 1 borehole completion record: Southern Thomson Project. Record 2018/10. Geoscience Australia, Canberra. Geological Survey of New South Wales Record GS2018/0200. http://dx.doi.org/10.11636/Record.2018.010

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http://dx.doi.org/10.11636/Record.2018.010

Euroli 1 borehole completion record iii

Contents

1 Introduction ............................................................................................................................................ 1 1.1 The Southern Thomson Project ....................................................................................................... 1

2 Borehole rationale, location and construction ....................................................................................... 3 2.1 Rationale and location ..................................................................................................................... 3 2.2 Borehole construction ...................................................................................................................... 5

3 Borehole lithology, petrography and stratigraphy .................................................................................. 8 3.1 Introduction ...................................................................................................................................... 8 3.2 Lithology ........................................................................................................................................... 8 3.3 Basement rock petrography ...........................................................................................................11 3.4 Stratigraphy ....................................................................................................................................13 3.5 Synthesis within the regional stratigraphic framework ...................................................................14

4 Borehole and drill core rock properties ................................................................................................16 4.1 Introduction ....................................................................................................................................16 4.2 Rock properties measurements .....................................................................................................16 4.3 Results ...........................................................................................................................................16

4.3.1 Natural gamma .........................................................................................................................16 4.3.2 Induction conductivity ...............................................................................................................17 4.3.3 Magnetic susceptibility .............................................................................................................19 4.3.4 Saturated bulk density ..............................................................................................................20 4.3.5 Rock properties data package .................................................................................................20

5 HyLogger data .....................................................................................................................................21 5.1 HyLogger data acquisition and processing ....................................................................................21 5.2 Results ...........................................................................................................................................22

5.2.1 Euroli 1 mud rotary chips ..........................................................................................................22 5.2.2 Euroli 1 diamond drill core ........................................................................................................22

5.3 Comparison with other logging ......................................................................................................23 5.4 HyLogger data package .................................................................................................................24 5.5 HyLogger data reprocessing ..........................................................................................................24

6 Groundwater ........................................................................................................................................27 7 Acknowledgements .............................................................................................................................30

8 References ..........................................................................................................................................31

Appendix A Borehole construction .........................................................................................................32

Appendix B Drilling activities and consumables .....................................................................................34

Appendix C Petrophysical equipment details .........................................................................................36 C.1 Borehole wireline logging equipment ............................................................................................36 C.2 Hand-held magnetic susceptibility logging equipment ..................................................................36 C.3 Analytical balance equipment (density determination) ..................................................................36

Appendix D Petrophysical data acquisition and processing ...................................................................37 D.1 Data acquisition and processing ...................................................................................................37 D.2 Equipment calibration ....................................................................................................................37 D.3 Data processing ............................................................................................................................38

iv Euroli 1 borehole completion record

Appendix E Euroli 1 Lithological and stratigraphic log ...........................................................................39

Appendix F Deviation survey ..................................................................................................................40 Appendix G Borehole log........................................................................................................................41

Euroli 1 borehole completion record v

Figures

Figure 1.1: Location of the Thomson Orogen in eastern Australia. The red box encompasses the Southern Thomson Project area. ....................................................................................................... 1

Figure 1.2: Location map of all boreholes drilled as part of the Southern Thomson Project. Background: TOPO 250K topographic map mosaic, Geoscience Australia. ........................................... 2

Figure 2.1: Location map of the Euroli 1 borehole with local waterbores. Background: TOPO 250K mosaic of Australia, Geoscience Australia. .................................................................................... 4 Figure 2.2: Location map showing the Euroli 1 borehole and solid geological basement interpretation from Purdy et al. (2014) and Purdy et al. (2018), over a first vertical derivative of total magnetic intensity (1VD TMI) image of the Magnetic Map of Australia 2015. ................................. 5

Figure 2.3: The Euroli 1 borehole site prior to drilling, looking east. ........................................................ 6

Figure 2.4: Mud rotary drilling operations at Euroli 1, looking south. ....................................................... 7

Figure 2.5: Image showing the partial rehabilitation of mud sumps at Euroli 1. The sumps have fully dried, are fenced with metal and awaiting backfilling with the original soil, looking north. Image courtesy of Bruce Hearn. ............................................................................................................... 7

Figure 3.1: Mud rotary chip sample layout at the Euroli 1 borehole site. Samples are laid out on hessian and plastic starting in the bottom left corner, moving right in runs of 10 m, with the sample from the deepest part of the borehole in the middle right of the image. Note the colour change in chips from the surface weathering zone (left) to unweathered Eromanga Basin rocks (right). In the right of the image 250 ml sample vials are laid out, in preparation for filling with chips for archiving and future analysis. .................................................................................................... 8

Figure 3.2: Euroli 1 lithological and stratigraphic graphic log. Lithology is summarised from the detailed lithological log attached in Appendix E. ....................................................................................10

Figure 3.3: Dry (above) and wet (below) field photos of typical diamond drill core from Euroli 1. .........11 Figure 3.4: Representative thin-section photomicrographs from the Euroli 1 borehole. The top image (A) is from ~111 m DL and the lower image (B) is from ~146 m DL. ..........................................12

Figure 3.5: Geological map of the Euroli 1 region overlain with AEM conductivity depth sections of flight lines 1280 and 1281, flown in 2014 (Roach, 2015). The background geology map is modified from the YANTABULLA 1:250,000 scale map sheet (Wallis and McEwan, 1962). Geological map symbols include: Qrs (black soil and claypans); Qcp (silt, clay); Qrd (Quaternary wind-blown sand); Qrt (silcrete colluvium); Tsi (Tertiary silcrete); and, K (Cretaceous sediments of the Rolling Downs Group). The conductivity depth sections highlight electrically resistive basement rocks close to surface to the east of the Euroli 1 borehole site, with cover thickness increasing to the west and east. According to the AEM data, cover thickness near the Euroli 1 borehole site should be ~70 m; drilling confirmed a cover thickness of 80 m. .......................................14

Figure 4.1: Lithology, stratigraphy, rock properties and borehole construction data for Euroli 1. The legend for lithology types and stratigraphy is the same as in Figure 3.1. For more detail on borehole construction refer to Appendix A. ............................................................................................18

Figure 5.1: Mineral spectra summary plot of the Euroli 1 mud rotary chips. ..........................................22

Figure 5.2: Mineral spectra summary plot of Euroli 1. ............................................................................23

Figure 5.3A: A comparison between spectral mineralogy, interpreted stratigraphy and borehole rock properties data from Euroli 1. The spectral mineralogy legends in the upper part of the log refer to the mud rotary drilled portion of the borehole <83.0 m TVD, and in the lower part to the diamond drilled portion to EOH. .............................................................................................................25

Figure 6.1: Stratigraphic log and borehole wireline rock properties for Boundary Bore (GW020767) redrill. ................................................................................................................................29

vi Euroli 1 borehole completion record

Figure 8.1: Euroli 1 borehole construction. .............................................................................................33

Euroli 1 borehole completion record vii

Tables

Table 2.1: Details for the Euroli 1 borehole. ............................................................................................. 3

Table 3.1: Interpreted stratigraphy of the Euroli 1 borehole. ..................................................................13

Table 4.1: Euroli 1 natural gamma interval statistics, with units in Counts Per Second (CPS). ............17

Table 4.2: Euroli 1 induction conductivity stratigraphic interval statistics. ..............................................19

Table 4.3: Euroli 1 magnetic susceptibility stratigraphic interval statistics. ............................................20

Table 4.4: Bulk density measurements on diamond drill core from Euroli 1. .........................................20 Table 6.1: Local waterbores within the Euroli 1 vicinity highlighting the overall sub-artesian water pressures present in the area. Refer to Figure 2.2 for locations. .................................................27

Table 6.2: Interpreted stratigraphy of Boundary Bore (GW020767) redrill. ...........................................28

Table 6.3: Boundary Bore (GW020767) redrill natural gamma interval statistics, with units in Counts Per Second (CPS)......................................................................................................................28

Table 6.4: Boundary Bore (GW020767) redrill induction conductivity stratigraphic interval statistics. .................................................................................................................................................28

Table 8.1: Euroli 1 drilling times and production rates. ..........................................................................34

Table 8.2: Euroli 1 drilling consumables used. .......................................................................................35

Table 8.3: Borehole wireline data acquisition steps in Euroli 1 ..............................................................37

Table 8.4: Deviation survey data for Euroli 1. ........................................................................................40

Euroli 1 borehole completion record 1

1 Introduction

1.1 The Southern Thomson Project The Thomson Orogen is a major component of the Paleozoic Tasmanides of eastern Australia that extends through large portions of central and southwest Queensland and northwest New South Wales (Figure 1.1). Much of the Thomson Orogen is buried under younger sedimentary basins (some up to several kilometres thick) and regolith cover, making it one of the most poorly understood elements of Australia’s geology. As a result, the mineral potential of the region is also poorly defined.

The Southern Thomson Project (the Project) is a collaborative investigation between the Commonwealth of Australia (Geoscience Australia) and its partners the State of New South Wales (Department of Planning and Environment, Geological Survey of New South Wales – GSNSW) and the State of Queensland (Department of Natural Resources, Mines and Energy, Geological Survey of Queensland – GSQ).

Figure 1.1: Location of the Thomson Orogen in eastern Australia. The red box encompasses the Southern Thomson Project area.

The Project aims to better understand the geological character and mineral potential of the southern Thomson Orogen region, focusing on the border between New South Wales and Queensland, by acquiring and interpreting multi-disciplinary geophysical, geochemical, geological and geochronological data. The primary intended impact of this work is to provide the mineral exploration

2 Euroli 1 borehole completion record

industry with pre-competitive data and knowledge that reduces risk and encourages mineral exploration in the region.

The pre-competitive data collection culminated in a drilling program of 12 boreholes within the project area of New South Wales and Queensland (Figure 1.2), targeting strategic basement rocks that will improve the understanding of the mineral potential of the southern Thomson Orogen and its geodynamic setting within the Tasmanides of eastern Australia.

Figure 1.2: Location map of all boreholes drilled as part of the Southern Thomson Project. Background: TOPO 250K topographic map mosaic, Geoscience Australia.


2 Borehole rationale, location and construction

I. C. Roach and R. Hegarty

2.1 Rationale and location The Euroli 1 borehole was drilled approximately 23 km SSW of Hungerford, Queensland (which is located on the New South Wales-Queensland border) (figures 1.2, 2.1, Table 2.1). The borehole was designed to test aeromagnetic anomalies in the basement rocks (Figure 2.2), test the electrical conductivity properties of cover and basement rocks to validate airborne electromagnetic (AEM) data (Figure 3.5), and to test pre-drilling geophysical cover thickness estimates (see Goodwin et al., 2017). The Euroli 1 borehole was commenced as a vertical mud rotary borehole and was completed as a deviated diamond borehole using a wedge.

Table 2.1: Details for the Euroli 1 borehole.

Hole ID Euroli 1

Site ID* Euroli 2*

Contractor DRC Drilling Pty Ltd

Drilling rig Sandvik DE880

Landholder Euroli Station

Title EL 8443

Status Closed, cemented to surface, cement cap installed, site remediation earthworks had not been completed by the time of publication

Location Longitude (GDA94): 144.350053° Latitude (GDA94): -29.199833° Easting (MGAZ55S): 242344 m Northing (MGAZ55S): 6766966 m Elevation (ellipsoidal): 120 m

Drilled length 153.7 m

Casing 0-76.3 m DL steel 168.28 mm OD cemented 0-83.0 m DL steel 114.30 mm OD HWT removable 83.0-153.7 DL m (end of hole - EOH) open hole

Casing cut-off depth 0.5 m below surface

Grouting Cement, from EOH to surface after removing HWT casing

Mud rotary drilled length

0-83.0 m DL (83.0 m DL)

Diamond drilled length

83.0-153.7 m DL (70.7 m DL)

Commencement date 14.07.2017

Completion date 20.07.2017

Deviation Deviated hole using a Hall-Rowe wedge

Deviation survey date 20.07.2017 (Appendix F)

GA Boreholes ENO 620173

*Project pre-drilling internal reference to site.


The Euroli 1 borehole was drilled as a vertical borehole and was wedged once the borehole reached competent basement to recover structural information from the oriented diamond drill core. Drilled lengths (DL) of features in the borehole are converted to True Vertical Depth (TVD) in the text and tables below unless otherwise labelled, and all measurements are relative to ground level.

Figure 2.1: Location map of the Euroli 1 borehole with local waterbores. Background: TOPO 250K mosaic of Australia, Geoscience Australia.


Figure 2.2: Location map showing the Euroli 1 borehole and solid geological basement interpretation from Purdy et al. (2014) and Purdy et al. (2018), over a first vertical derivative of total magnetic intensity (1VD TMI) image of the Magnetic Map of Australia 2015.

2.2 Borehole construction The Project team at this site included scientists from GA and the GSNSW, a licensed water bore driller, and the contractor’s drilling team. The borehole was drilled as a vertical mud rotary borehole to refusal at 83.0 m DL using two small inter-connected sumps (approximately 3 x 5 x 1.5 m) to catch mud rotary drill cuttings and a Solids Recovery Unit (SRU) in the drilling fluid circulation system to remove silt and clay. On reaching competent basement rocks at 83 m DL diamond drilling commenced


using HQ3 size equipment, with fluid circulated through the same sumps and SRU to remove silt, until the basement rocks became very competent. A Hall-Rowe wedge was then inserted between 116 m DL and 121 m DL to deviate the borehole sufficiently to allow the core orientation device to function. Diamond drilling at HQ3 size continued to the End Of Hole (EOH) at 153.7 m DL.

Before commencement the Project team reviewed the standing water levels in the area to assess the likelihood of artesian groundwater conditions within the borehole by assessing bore cards for local water bores (Figure 2.1) available from the NSW Department of Primary Industries Office of Water (http://allwaterdata.water.nsw.gov.au/water.stm).

The Project team worked to ensure that the drilling fluid was correctly weighted before aquifers were likely to be encountered to prevent the accidental escape of artesian groundwater. The borehole was fully cased with steel casing through the entire cover sequence into competent basement rock before commencement of diamond drilling operations. This was to prevent swelling clays in the Eromanga Basin sequence from closing the borehole, to prevent groundwater escape, to prevent groundwater mixing between aquifers and to prevent drilling fluids from contaminating groundwater in accordance with the requirements of the Minimum Construction Requirements for Water Bores In Australia (National Uniform Drillers Licensing Committee, 2011). More information regarding borehole construction and drilling consumables is available in Appendix A and Appendix B and images of the site before, during and after drilling are included in Figures 2.3 to 2.5.

Figure 2.3: The Euroli 1 borehole site prior to drilling, looking east.

http://allwaterdata.water.nsw.gov.au/water.stm


Figure 2.4: Mud rotary drilling operations at Euroli 1, looking south.

Figure 2.5: Image showing the partial rehabilitation of mud sumps at Euroli 1. The sumps have fully dried, are fenced with metal and awaiting backfilling with the original soil, looking north. Image courtesy of Bruce Hearn.


3 Borehole lithology, petrography and stratigraphy

R. Hegarty, I. C. Roach, C. B. Folkes and P. Gilmore

3.1 Introduction Cuttings and diamond drill core from Euroli 1 were logged on site by GSNSW and GA geologists. Cuttings were collected from the mud rotary-drilled Quaternary, Cenozoic and Mesozoic cover sequence and the top of basement at 1 m intervals to 83.0 m DL. Sampling of some intervals was incomplete; however the overall cutting quality and volume was high. Most 1 m intervals were represented by an amount of cuttings sufficient to fill a chip tray and a 250 ml sample vial for future analysis. Cuttings were washed and laid out to dry (Figure 3.1) before lithological logging, sampling and analysis with a hand-held magnetic susceptibility device.

Key parameters of grainsize, colour and organic matter content, and any other major changes, were recorded. The basement drill core interval (83.0-153.7 m DL) was also logged and photographed on site.

Figure 3.1: Mud rotary chip sample layout at the Euroli 1 borehole site. Samples are laid out on hessian and plastic starting in the bottom left corner, moving right in runs of 10 m, with the sample from the deepest part of the borehole in the middle right of the image. Note the colour change in chips from the surface weathering zone (left) to unweathered Eromanga Basin rocks (right). In the right of the image 250 ml sample vials are laid out, in preparation for filling with chips for archiving and future analysis.

3.2 Lithology Euroli 1 penetrated 80 m TVD of cover sediments and sedimentary rocks before entering finely laminated, crenulated, spotted, fine-grained grey schist of the basement. Lithological types observed in the hole are described below and in Figure 3.2.


Modern regolith at Euroli 1 includes red-brown silt and fine sand from 0 m TVD to 2 m TVD, unconsolidated in the top metre, but as a hardpan in the base with dominantly sub-horizontal calcrete laminae up to 5 mm thick filling cracks within the hardpan. This overlies a zone of cream, red-brown or beige coloured mottled clays from 2 m TVD to 12 m TVD that contain some gravelly fragments of quartz, iron and manganese oxyhydroxides and calcrete crack-fills. Below this lies a zone of beige-cream or red-brown coloured mottled siltstone and fine-grained sandstone layer between 12 m TVD and 19 m TVD containing iron and manganese oxyhydroxide fragments. Below this the borehole penetrated a zone between 19 m TVD and 29 m TVD of dominantly grey-purple coloured semi-consolidated shale with iron and manganese oxyhydroxide coatings and minor quartz fragments. Between 29 m TVD and 49 m TVD the borehole penetrated a zone of pallid, puggy dominantly white claystone with rare ferruginised patches, becoming increasingly mottled towards its base at 49 m TVD, and changing colour from cream to purple mottles and then solid grey at 55 m TVD. This colour change between pallid and grey clays is regarded as the base of surface weathering, confirmed by a large change in electrical conductivity in the borehole wireline induction conductivity log (Figure 4.1).

Below 55 m TVD to 74 m TVD the borehole penetrates grey claystone containing minor hard bands (well-consolidated shales) and carbonaceous bands, as well as including some scattered gritty fragments. Between 74 m TVD and 78 m TVD the borehole penetrates gravel consisting of silt- to granule-sized lithic and quartz fragments with abundant framboidal pyrite in the top metre. Quartz and lithic fragments are generally flat, platy and subrounded.

Between 78 m TVD and 84 m TVD the borehole encountered harder, fresher schistose lithic and quartz fragments until mud rotary drilling refusal at 84 m TVD in hard, competent basement rock.

Basement rocks from 84 m DL to EOH consist of grey-toned, fine-grained retrograde schist (Figure 3.3). Rocks display obvious bedding laminae that alternate between light-toned, quartzose layers and dark-toned, mica-rich layers, which have a well-developed crenulation cleavage and a spotted appearance (caused by cordierite porphyroblasts; see Figure 3.4). Rocks in the top of the basement are quite fractured and weathered, with fracture density falling with decreasing weathering until the rocks become quite competent at ~101 m DL. Below ~140 m DL, the core becomes darker with a higher magnetic susceptibility (see Figure 4.1). In the field this was thought to represent a more mafic component to the original sediments. The basement rocks contain prominent quartz veins in the upper portion of the core, and have prominent alteration haloes in the lower portion centred on quartz sand-rich layers. Thin pyrite veins that are parallel to bedding are scattered throughout the basement. The rock was classified in the field as quartz-biotite schist.


Figure 3.2: Euroli 1 lithological and stratigraphic graphic log. Lithology is summarised from the detailed lithological log attached in Appendix E.


Figure 3.3: Dry (above) and wet (below) field photos of typical diamond drill core from Euroli 1.

3.3 Basement rock petrography Three representative thin-sections were taken at ~111 m DL (two samples) and ~146 m DL (one sample). The lithology is classified as quartz-biotite-muscovite schist with altered/retrograded cordierite porphyroblasts. There are alternating quartz- and mica-rich layers that reflect the original


bedding. The cordierite porphyroblasts are square to rectangular, containing an early fabric now composed of chlorite, biotite and lesser quartz that is of a different orientation that the surrounding ‘host’ fabric (Figure 3.4A). These porphyroblasts have been rotated. There is also apatite growth as inclusions in biotite and as separate crystals within the matrix. In the sample taken at ~146 m DL, there are some meta-carbonaceous layers with cordierite porphyroblasts almost un-retrograded, showing sector zoning. There is also randomly oriented metamorphic biotite (that grew during contact metamorphism and growth of the cordierite), with disseminated pyrite scattered through the thin-section. A second porphyroblast type consisting of acicular actinolite crystals radiating from central amphiboles is also observed in the sample at ~146 m DL (Figure 3.4B). This suggests that this bed may have represented a more mafic source, perhaps mafic-intermediate volcaniclastic sandstone that was subsequently metamorphosed to produce growth of actinolite.

Figure 3.4: Representative thin-section photomicrographs from the Euroli 1 borehole. The top image (A) is from ~111 m DL and the lower image (B) is from ~146 m DL.


Three phases of deformation/metamorphism can be observed in all samples:

1. deformation with early biotite growth causing the main fabric

2. hornfels (contact metamorphism) with growth of cordierite porphyroblasts

3. deformation with slight shear causing kink bands and rotation of porphyroblasts, and (retrograde) growth of secondary biotite and chlorite.

The deformation around the cordierite porphyroblasts caused crenulations as observed in hand specimens of the drill core. The lithologies associated with this sample are meta-pelitic sandstone (mica-rich layers), a meta-sandstone (quartz-rich layers) and a siltstone hornfels (spotted cordierite fabric).

3.4 Stratigraphy The stratigraphy in the Euroli 1 borehole (Table 3.1) is interpreted based on geological mapping on the YANTABULLA (Wallis and McEwan, 1962) and EULO (Senior et al., 1969) 1:250,000 geological maps, interpretations from regional water bores and regional stratigraphic drill holes described by Hawke and Cramsie (1984).

The upper unit encountered between the surface and 2 m TVD in the borehole is described by Wallis and McEwan (1962) as “Qd”, wind-blown sand with minor clay pans, which is in keeping with the aeolian red-brown fine sand and silt sheets that cover the region and are part of the present-day Murray-Darling hydrogeological basin. This lies above an interval of ~10 m of bleached clay, then coarse sand and gravel between 12 m TVD and 19 m TVD, interpreted here to be Cenozoic alluvial sediment of the Murray-Darling hydrogeological basin to 19 m TVD. The house bore at Euroli Station draws from this shallow aquifer, which is regarded as being a moderately good quality, but low flow, sub-artesian aquifer.

Below this between 19 m TVD and 74 m TVD lies an interval of ~57 m of clay and siltstone interpreted as belonging to the Wallumbilla Formation; these rocks become less weathered until the base of surface weathering is reach at ~55 m TVD, after which the package is uniformly dark grey in tone.

Table 3.1: Interpreted stratigraphy of the Euroli 1 borehole.

Province Stratigraphic unit Top depth (m TVD)

Bottom depth (m TVD)

True thickness (m)

No province Quaternary sand sheet 0.00 2.00 2.00

No province Clay 2.00 12.00 10.00

No province Gravelly sand 12.00 19.00 7.00

Eromanga Basin Wallumbilla Formation 19.00 74.00 55.00

Eromanga Basin Wyandra Sandstone Member 74.00 78.00 4.00

Thomson Orogen Basement – Nebine Metamorphics 78.00 153.70 EOH 75.70

Between 74 m TVD and 78 m TVD lies a gravelly layer consisting of lithic and quartzose chips composed of local basement fragments, considered here to be part of the Wyandra Sandstone Member of the Cadna-owie Formation. This is the local major aquifer and many of the water bores in the area draw from this unit including Boundary Bore (GW020767), ~5.2 km to WNW. Boundary Bore had been recently redrilled, and was logged as part of this exercise (see Section 6). The gravel in this


interval is obviously locally derived, as evidenced by the size and shape of the particles, and is interpreted to be sourced from a bedrock rise to the east of the site, revealed by airborne electromagnetic (AEM) data flown in 2014 (Roach, 2015) and shown in Figure 3.4.

The basement rocks are interpreted as belonging to the metamorphic background rocks to the Thomson Orogen, part of the Nebine Metamorphics (Purdy et al., 2018).

Figure 3.5: Geological map of the Euroli 1 region overlain with AEM conductivity depth sections of flight lines 1280 and 1281, flown in 2014 (Roach, 2015). The background geology map is modified from the YANTABULLA 1:250,000 scale map sheet (Wallis and McEwan, 1962). Geological map symbols include: Qrs (black soil and claypans); Qcp (silt, clay); Qrd (Quaternary wind-blown sand); Qrt (silcrete colluvium); Tsi (Tertiary silcrete); and, K (Cretaceous sediments of the Rolling Downs Group). The conductivity depth sections highlight electrically resistive basement rocks close to surface to the east of the Euroli 1 borehole site, with cover thickness increasing to the west and east. According to the AEM data, cover thickness near the Euroli 1 borehole site should be ~70 m; drilling confirmed a cover thickness of 80 m.

3.5 Synthesis within the regional stratigraphic framework On the basement interpretation map of Purdy et al. (2018) basement in this area is thought to be ‘possible intermediate plutonic/volcanic unit’, but the drilled basement lithology intersected by Euroli 1 is a metasedimentary schist. It is possible this unit is related to the nearby Twin Tanks Metamorphics or Nangunyah Zone currently mapped to the south and east. Further, the suggested mafic-intermediate material responsible for producing the amphibole and actinolite porphyroblasts could have come from rocks with mafic lithologies of the nearby Nangunyah or Kerrininna zones (Purdy et al., in prep.). The three phases of deformation/metamorphism observed in the thin-sections of the basement rocks in this drill hole provide useful information for the metamorphic, deformation and magmatic activity in the region. The contact metamorphism (with growth of cordierite and minor actinolite porphyroblasts) of a siliciclastic sedimentary source could have been caused by the Hungerford Granite, nearby mafic to intermediate intrusions of the Kerrininna Zone or the currently mapped plutonic/volcanic unit of Purdy et al. (in prep.).

Therefore the interpreted geological history of the metasedimentary schist sampled in Euroli 1 is:

• Deposition of siliciclastic turbidites – black shales to sandstone beds. Presence of (later) amphibole and actinolite porphyroblasts may indicate an intermediate to mafic provenance for some beds


• Fabric development and regional metamorphism

• Contact metamorphism – high T porphyroblast (cordierite, with minor actinolite and amphibole in certain beds) growth across the first fabric. The heat source could be the Hungerford Granite (~419 Ma), nearby mafic to intermediate intrusions of the Kerrininna zone (age unknown) or the currently mapped plutonic/volcanic unit (age unknown) of Purdy et al. (in prep.)

• A second deformation event with porphyroblast rotation into a second fabric.

The two deformation/metamorphic events that are inferred to pre- and post-date the contact metamorphism could be related to Benambran, Bowning-Bindian and/or Tabberabberan-aged events. Further analyses of the timing of metamorphism would help to better constrain this interpretation. Based on the metamorphic mineral assemblages interpreted to have grown during these two events, this basement rock has undergone metamorphism to mid-upper greenschist facies (biotite grade).

Geochemical and geochronological (Cross et al., in prep) analyses will be forthcoming and will better help to place the rock unit sampled with this drillhole in a regional context.


4 Borehole and drill core rock properties

I. C. Roach, R. Hegarty and S. L. Jones

4.1 Introduction Rock properties data provide the petrophysical link between observed geophysics and under-cover geology. Rock properties data may be used to help constrain models and inversions of potential fields (magnetic, gravity) geophysical data, resulting in more accurate predictions of geology from geophysics. Electrical conductivity rock properties data can also be used to constrain inversions of airborne electromagnetic (AEM) data for regional geological and groundwater resources mapping.

4.2 Rock properties measurements Rock properties measurements were performed in situ using borehole wireline logging tools, using hand-held equipment on mud rotary drill chips and diamond drill core in the field, and using hand-held and laboratory equipment in the GSNSW core repository at Londonderry, New South Wales. Rock properties measurements include:

• dual channel induction (electrical) conductivity (borehole wireline)

• natural gamma (borehole wireline)

• magnetic susceptibility (borehole wireline on uncased basement rocks and hand-held on mud rotary drill chips and diamond drill core)

• bulk saturated density (drill core only).

Borehole wireline logging was performed in stages, where possible, between drilling and subsequent borehole casing installation owing to the necessities of safely drilling and casing boreholes through the Great Artesian Basin, and preventing the uncontrolled escape of artesian groundwater. Every attempt was made to obtain borehole wireline rock properties measurements from open, uncased sections of each borehole. This was in order to obtain induction conductivity data to help validate airborne electromagnetic data collected in 2014 and 2016, detailed by Roach (2015) and Brodie et al. (in prep). Details of the equipment used are provided in Appendix C.

No in situ density measurements were obtained.

Data acquisition, processing and quality control details are included in Appendix D and an enlarged-scale log is presented in Appendix G.

4.3 Results

4.3.1 Natural gamma

Natural gamma data were obtained along the full length of the Euroli 1 borehole (Figure 4.1), from uncased sections in stages as they became available, and through casing at the completion of drilling.


The interval statistics included in Table 4.1 are taken from a composite of data from the uncased borehole, included in the attached Log ASCII Standard (LAS) file. Natural gamma data are processed according to the description in Appendix D and are presented using American Petroleum Institute (API) units.

Natural gamma data are generally subdued in the Eromanga Basin sequence, with small spikes or offsets signifying stratigraphic unit boundaries, e.g. between the Quaternary sand cover and the Cenozoic alluvial sequence, and between the Cenozoic sequence and the Wallumbilla Formation. The natural gamma response of the Wyandra Sandstone Member rises from the average value of the overlying Wallumbilla Formation (~62 API units) towards the contact with the underlying basement schists. This is due to the fact that the Wyandra Sandstone Member here is composed of bedrock-derived lithic fragments derived locally from sediment shedding from a bedrock palaeohigh to the east of the site (Figure 3.5). The basement response is more elevated and responds to the palaeoweathering surface on basement (deeply weathered between the top of basement at 78 m TVD and ~82.8 m TVD), and to compositional variation in the basement schists including more psammitic (sandy, and therefore slightly more zircon-rich) and more pelitic compositional layers.

The Euroli 1 borehole was drilled using a Hall-Rowe wedge to obtain an offset on the diamond-cored portion of the borehole for structural reconstructions. The wedge is visible in the natural gamma data as a zone of attenuation between 115 m DL and 121 m DL, and is marked in Figure 4.1. All other variability in the natural gamma data is caused by natural compositional variation in the cover and basement rocks.

Table 4.1: Euroli 1 natural gamma interval statistics, with units in Counts Per Second (CPS).

Strat unit Minimum (API) Maximum (API) Average (API) SD (API) Quaternary 36.89 81.17 58.30 11.53

Cenozoic 14.04 100.85 64.05 16.05

Wallumbilla Formation 18.23 149.26 61.74 18.62

Wyandra Sandstone Member 34.73 139.96 72.42 17.75

Basement 75.87 313.68 227.59 34.54

4.3.2 Induction conductivity

Induction conductivity data were collected in uncased portions of the Euroli 1 borehole. Small data gaps of single readings occurred throughout the dataset due to transient telemetry errors within the acquisition system, and were edited in the final dataset. A large data gap occurs between ~75.3 m TVD and ~83.5 m TVD where cuttings filled the bottom of the hole before casing was inserted (Figure 4.1).

Induction conductivity data from Euroli 1 illustrate that the borehole penetrated variably conductive cover of the Eromanga Basin, and that surface weathering affects the electrical conductivity to ~55 m TVD. Small, brackish groundwater aquifers in the Cenozoic alluvial cover are slightly more electrically conductive (~170 mS/m compared to a background of 30 mS/m to 50 mS/m). The electrical conductivity of the cover sequence peaks below the bottom of surface weathering in the Wallumbilla Formation at ~450 mS/m (Table 4.2), which is visible as a strong conductor in the base of AEM data shown in Figure 3.5.


Figure 4.1: Lithology, stratigraphy, rock properties and borehole construction data for Euroli 1. The legend for lithology types and stratigraphy is the same as in Figure 3.1. For more detail on borehole construction refer to Appendix A.


Basement is relatively electrically resistive, averaging ~3 mS/m, except for intervals that coincide with intervals of elevated magnetic susceptibility, shown by petrography to be magnetite-enriched zones within the host rock. A weak zone of elevated electrical conductivity occurs in the basement between ~86 m TVD and 104 m TVD, coinciding with weak magnetic susceptibility anomalies. A strong zone of electrical conductivity occurs between ~138 m TVD and the EOH coinciding with a strong magnetic susceptibility anomaly and visible magnetite in the core.

The interval between 115 m DL and 121 m DL shows anomalous electrical conductivity, but is associated with the steel wedge inserted into the borehole (Figure 4.1).

Negative departures in induction conductivity data are associated with the edge effects of the steel wedge, and with the transition into the magnetite-enriched zones within the basement.

Table 4.2: Euroli 1 induction conductivity stratigraphic interval statistics.

Strat unit Minimum (mS/m) Maximum (mS/m) Average (mS/m) SD (mS/m) Medium channel Quaternary 36.45 37.64 37.15 0.40

Cenozoic 32.07 172.59 71.25 32.98



Basement (including steel wedge) -24.63 1888.24 79.12 288.46

Basement (excluding steel wedge) -24.63 1296.32 15.39 55.57

Deep channel Quaternary 30.38 33.11 31.71 0.93

Cenozoic 33.93 219.76 93.78 42.73



Basement (including steel wedge) -33.14 1413.54 40.57 177.45

Basement (excluding steel wedge) -33.14 1378.14 15.97 71.18

4.3.3 Magnetic susceptibility

Magnetic susceptibility data were collected using a handheld magnetic susceptibility meter (see Appendix C for more detail) along the length of the borehole from mud rotary chip samples and the diamond drill core. A data gap exists between the end of mud rotary drilling and the commencement of diamond drilling due to poor mud rotary sample recovery, between 76 m TVD and 82 m TVD; however the data appear to be consistent across this gap. Magnetic susceptibility statistics for stratigraphic intervals are presented in Table 4.3.

The magnetic susceptibility of the Eromanga Basin cover sequence is subdued. Slightly elevated values occur at the surface, associated with scattered maghemite nodules and hematite coatings on quartz sand grains in the covering sand sheet. Cenozoic alluvial gravels also contain slightly elevated magnetic susceptibility due to the presence of bedrock fragments.

Basement rocks have subdued magnetic susceptibility except for magnetite-enriched zones (correlated with elevated electrical conductivity) between ~86 m TVD and 104 m TVD, coinciding with weak magnetic susceptibility anomalies, and between ~138 m DL and the EOH, coinciding with a


strong magnetic susceptibility anomaly and visible magnetite in the core. We surmise that the magnetite-enriched zones in this rock cause the aeromagnetic anomaly present at the site.

Table 4.3: Euroli 1 magnetic susceptibility stratigraphic interval statistics.

Minimum (SI x 10-5) Maximum (SI x 10-5) Average (SI x 10-5) SD (SI x 10-5) Quaternary 69.12 95.04 82.08 10.58

Cenozoic 12.96 69.12 24.53 10.94



Basement 0.00 1488.96 121.78 267.12

4.3.4 Saturated bulk density

Samples of diamond drill core were submitted to the Coffey Services Australia Pty Ltd laboratory in Fyshwick, Australian Capital Territory, for determination of dry bulk density, saturated bulk density, grain density and apparent porosity according to Australian Standard AS 1141.6.1-2000, presented in Table 4.4.

Table 4.4: Bulk density measurements on diamond drill core from Euroli 1.

From (m DL) To (m DL) n samples Mean dry bulk density (g/cm3)

Mean saturated bulk density (g/cm3)

Mean grain density (g/cm3)

Mean apparent

porosity (%)

111.6 114.12 4 2.81 ± 0.01 2.82 ± 0.01 2.82 ± 0.01 0.11 ± 0.08

147.8 148.15 2 2.82 ± 0.01 2.82 ± 0.01 2.82 ± 0.01 0.00 ± 0.00

148.8 148.9 1 2.78 2.78 2.78 0.00

± error is calculated as 1 standard deviation of the sample population

4.3.5 Rock properties data package

Rock properties data for Euroli 1 are compiled as a Log ASCII Standard (LAS) file available for free download from the GA website and through the Rock Properties Explorer discovery tool (http://www.ga.gov.au/explorer-web/rock-properties.html). Rock properties data are also included in a Web Mapping Service (WMS) and Web Feature Service (WFS) from GA (http://www.ga.gov.au/data-pubs/web-services/ga-web-services).

http://www.ga.gov.au/explorer-web/rock-properties.html

http://www.ga.gov.au/data-pubs/web-services/ga-web-services

http://www.ga.gov.au/data-pubs/web-services/ga-web-services


5 HyLogger data

D. B. Tilley and I. C. Roach

5.1 HyLogger data acquisition and processing Diamond drill cores and mud rotary chips were spectrally scanned using the CSIRO-developed HyLogger™ system at NSW Planning and Environment’s HyLogger™ facility in the W.B. Clarke Geoscience Centre, Londonderry, NSW. The resultant spectral data were analysed using The Spectral Geologist™ (TSG) software, also developed by the CSIRO. This instrument measures spectra in three different wavelength bands (Mason and Huntington, 2012):

• the visible-near infrared (VNIR) between 380 and 1072 nm • the short-wave infrared (SWIR) between 1072 and 2500 nm • the thermal infrared (TIR) from 6000 and 14,500 nm.

The HyLogger™ instrument collects spectral data and imagery of geological materials on a systematic basis. The near-continuous nature and abundance of the spectral data collected provides ideal datasets which can be processed to identify systematic changes in the overall mineral assemblage along diamond drill cores and chip trays. This can highlight shifts in the nature of individual mineral species present (particularly chlorite and white mica), and identify changes in the relative abundance of specific minerals.

Prior to scanning, the diamond drill core was cleaned with a vacuum cleaner and moistened cloth to remove dust, dirt and in-tray debris. Disjointed core pieces were realigned and reconnected within sections of a tray to make a continuous core stick. Following this, the core was allowed to dry to reduce H2O spectral interference prior to scanning. In contrast, the only preparation done on the chips was that they were allowed to dry within their trays for a few days in open air.

A number of specialised scalars were used for inferring changes in the composition of white mica and chlorite and for estimating their relative abundances in core and chips.

For white mica composition and relative abundance The Spectral Assistant (TSA™) batch scalars White Mica Wavelength v1.2 and White Mica Intensity v1.2 were used. These scalars are based on the wavelength and depth of the Al-OH absorption feature in the short-wave infrared (SWIR) spectrum. It has been noted by Pontual et al. (2008) that the absorption minimum ranges from 2184 nm for paragonite (Na-sericite), to 2202 nm for muscovite (“normal” potassic compositions) and 2225 nm for phengite compositions (Mg-Fe substituted sericites). Also, the scalar’s batch script specifies that any identification of montmorillonite by TSA™ will provide a null result, whilst samples classified by TSA™ as bearing highly crystalline and/or illitic white micas are included in the determinations. The highly crystalline white micas include muscovite, phengite and paragonite whilst the illitic white micas include illite, phengitic illite and paragonitic illite. The depth of the feature provides an estimation of the relative abundance of white mica within core and chips.

The inferred composition and relative abundance of chlorite group minerals were determined using the following TSG™ Feature Extraction (FeatEx) scalars:

• chlorite composition: FeatEx Wvl, 2253 nm ± 10 nm • chlorite relative abundance: FeatEx Depth, 2253 nm ± 10 nm.


These scalars were used to determine the wavelength and depth of the Fe-OH absorption feature in the SWIR spectrum. The chlorite Mg-OH feature can be affected by the presence of carbonate, which overlaps the chlorite Mg-OH absorption. Consequently, it is more reliable to use the Fe-OH absorption feature for inferring the composition of chlorite rather than the Mg-OH feature. Pontual et al. (2008) have shown that this feature varies from 2245 nm for Mg-chlorite to 2261 nm for Fe-chlorite. The depth of the feature provides an estimation of the relative abundance of chlorite within the core/chips.

5.2 Results

5.2.1 Euroli 1 mud rotary chips

The mud rotary chips from the Euroli 1 borehole are composed mainly of kaolin (kaolinite), smectite (montmorillonite), white mica (muscovite), sulfate (gypsum), quartz, K-feldspar (microcline) and plagioclase (albite) (Figure 5.1).

The white mica is tending to phengite (Al-OH: 2210 nm) at the top of the borehole to muscovite (Al-OH: 2198 nm) at the bottom. This is consistent with the muscovitic white mica observed throughout the diamond drilled portion of the borehole.

At the bottom of the mud rotary drilled portion of the borehole, chlorite is detectible as a small Fe-OH absorption feature in spectra at around 2256 nm. Chlorite, with the same Fe-OH feature wavelength, is observed in the diamond drilled portion of the borehole. The TSA™ algorithm in TSG™ does not identify the presence of chlorite at the base of the mud rotary drilled portion of the borehole, perhaps due to its relatively low abundance.

Figure 5.1: Mineral spectra summary plot of the Euroli 1 mud rotary chips.

5.2.2 Euroli 1 diamond drill core

Basement rocks in Euroli 1 consist of a sequence of interlayered fine grained psammitic and pelitic schists. The pelitic layers are composed mainly of white mica, chlorite and quartz with minor dark mica


(biotite) and plagioclase (albite) (Figure 5.2). The white mica in these zones is mostly muscovite, as evidenced by the wavelength of the Al-OH absorption feature at 2198 nm, whilst the chlorite ranges from Fe-Mg chlorite to Fe chlorite, i.e. the Fe-OH feature ranges from 2254 nm to 2260 nm.

In contrast, the psammitic layers are predominantly quartz-rich, with minor dark mica (biotite), K-feldspar (microcline and orthoclase) and Na and Ca plagioclase varieties present.

A few narrow zones composed of chlorite-quartz-epidote-carbonate are apparent, scattered along the length of the core.

Figure 5.2: Mineral spectra summary plot of Euroli 1.

5.3 Comparison with other logging The stratigraphy in the Euroli 1 borehole was interpreted from lithological textures and mineralogy based on knowledge from other boreholes in the region, regional geological mapping in the EULO and YANTABULLA 1:250,000 geological map sheets, descriptions from Hawke and Cramsie (1984) and borehole wireline geophysical data. These interpretations are tested against the spectral mineralogy of returned mud rotary chips and diamond drill core from the borehole in Figure 5.3A, B.

The spectral mineralogy compares very favourably with the other logging data in that stratigraphic boundaries interpreted from the chip and core logging are generally within close agreement with changes in bulk mineralogy derived from the spectral mineralogy data in fresh rocks. The mineral spectra are complicated by two weathering overprints:

1. From surface to ~54 m TVD, consisting dominantly of kaolinite-smectite related to surface weathering. The boundary between the Cenozoic alluvium and the underlying Wallumbilla Formation, over which the surface weathering extends, is however marked downwards by the loss of smectite. The appearance of sulphate and a consistent relative abundance of silica and feldspars mark the boundary between surface weathering and the unweathered Wallumbilla Formation below.


2. A palaeoweathering overprint on basement rocks from the basement-cover interface at 78 m TVD to ~100 m TVD, visible as a kaolinite and smectite, which are lost below ~100 m TVD.

The spectral logging also compares very favourably with borehole induction conductivity data, where there is a good correlation between higher electrical conductivity values and the presence of sulphate in the Wallumbilla Formation. There appears to be little correlation between magnetic susceptibility in the mud rotary chips and diamond drill core and spectral mineralogy. The diamond cored portion of the Euroli 1 borehole passed through two intervals of magnetite metasomatic replacement, a weak zone between ~104 m TVD and ~106 m TVD, and a strong zone between ~138 n TVD and ~152 m TVD. The only noticeable correlation is the abundance of invalid readings in the SWIR mineral spectra in the lower interval

5.4 HyLogger data package The HyLogger data package consists of drill core data processed to Level 1F (all metadata tables updated, optimum database loadable level, further updates possible) that can be opened and viewed using The Spectral Geologist (TSG™) Viewer software. This software can be freely downloaded from CSIRO via the following link:

https://research.csiro.au/thespectralgeologist/support/downloads/

This package also contains individual core tray images in .JPG format, and a mosaic of all the core trays arranged it order also in .JPG format. These images are referenced images and can be interactively interrogated when opened in TSG program. The data will also be made available through the AuScope National Virtual Core Library (NVCL) portal (http://portal.auscope.org/portal/gmap.html) and Geoscience Australia’s AUSGIN portal (http://portal.geoscience.gov.au/gmap.html).

5.5 HyLogger data reprocessing Geoscience Australia commissioned CSIRO Mineral Resources to perform a quality assessment of the HyLogger data package by reprocessing the original dataset described above. The results of the assessment indicate that the original TSA-derived mineralogy for the Congararra 1 borehole was generally a good match for the scalar-derived mineralogy calculated during the reprocessing (Lau et al., in prep) except that plagioclase is under-represented, and biotite may be erroneously identified. After acceptance, the reprocessed dataset will be available through the NVCL and AUSGIN portals listed above.



http://portal.auscope.org/portal/gmap.html

http://portal.geoscience.gov.au/gmap.html


Figure 5.3A: A comparison between spectral mineralogy, interpreted stratigraphy and borehole rock properties data from Euroli 1. The spectral mineralogy legends in the upper part of the log refer to the mud rotary drilled portion of the borehole <83.0 m TVD, and in the lower part to the diamond drilled portion to EOH.


Figure 5.3B: legend for Figure 5.4A.


6 Groundwater

I. C. Roach

Local aquifers include Cenozoic gravels and the Mesozoic Wyandra Sandstone Member of the Cadna-owie Formation. Hydraulic heads around Euroli 1 are all below ground level, and appear to have been since original drilling, resulting in only sub-artesian water pressures. Local waterbores are listed in Table 6.1, highlighting the sub-artesian water levels present in the region.

Table 6.1: Local waterbores within the Euroli 1 vicinity highlighting the overall sub-artesian water pressures present in the area. Refer to Figure 2.2 for locations.

Bore ID Distance & bearing

Depth to main aquifer (m)

SWL when drilled (year)

Most recent SWL (year)

Aquifer

GW020766 2.0 km NW 28.96 -12.2 (1963) NA Cenozoic gravel

GW020767 (Boundary Bore)

5.2 km WNW 118.87 -22.9 (1963) NA Wyandra Sandstone member

GW016893 5.5 km ESE 17.68 -17.7 (1958) NA Cenozoic gravel

All SWLs are below ground level

No artesian groundwater was detected in Euroli 1, although the borehole intersected the Wyandra Sandstone Member of the Cadna-owie Formation between 74 m TVD and 78 m TVD (4 m unit thickness).

Boundary Bore (GW020767; figures 2.1, 3.5) had been recently redrilled by the landholder ~6 m W of the original waterbore prior to the Project team arriving on site at Euroli 1. The waterbore had not yet had a pump installed so the Project team took the opportunity to wireline log this borehole while in the area. The redrilled Boundary Bore had steel casing installed to ~9 m depth, and was then cased with PVC and plastic screens into the Wyandra Sandstone Member (Figure 6.1). No lithological log could be constructed for the Boundary Bore redrill because the drilling contractor had collected poor quality composite samples only every 6 m, but the stratigraphy could be interpreted from the borehole wireline log and the bore card for the original Boundary Bore.

Borehole wireline logs from the Boundary Bore redrill are similar to those from Euroli 1 in that:

• The natural gamma signature is very subdued in the Cenozoic alluvial cover due to weathering, with spikes probably signifying more labile sediments or resistate minerals such as zircon and monazite in near-surface gravels. The natural gamma signature of the Wallumbilla Formation and the Wyandra Sandstone Member are also subdued, but relatively uniform, except for a strong negative departure at the Wallumbilla Formation-Wyandra Sandstone Member boundary.

• The induction conductivity profile in the borehole is reflective of that in Euroli 1 in that electrical conductivity reaches a maximum in the Wallumbilla Formation below ~60 m depth, indicating the approximate depth of surface weathering, and is low in the Wyandra Sandstone Member indicating the quartz- and lithic-rich composition and the presence of fresh to only slightly


brackish groundwater. While no water quality data are available for Boundary Bore, the salinity description is labelled as ‘good’ in the bore card.

Stratigraphic intervals (Table 6.2) and interval statistics for borehole wireline rock properties data are presented below for natural gamma (Table 6.3) and induction conductivity (Table 6.4)

Table 6.2: Interpreted stratigraphy of Boundary Bore (GW020767) redrill.

Province Stratigraphic unit Top depth (m TVD)

Bottom depth (m TVD)

True thickness (m)

No province Cenozoic alluvium 0.00 16.00 16.00

Eromanga Basin Wallumbilla Formation 16.00 100.00 84.00

Eromanga Basin Wyandra Sandstone Member 100.00 140.00 EOH 40.00

Table 6.3: Boundary Bore (GW020767) redrill natural gamma interval statistics, with units in Counts Per Second (CPS).

Strat unit Minimum (API) Maximum (API) Average (API) SD (API) Cenozoic alluvium 4.42 117.69 45.29 24.39



Table 6.4: Boundary Bore (GW020767) redrill induction conductivity stratigraphic interval statistics.

Strat unit Minimum (mS/m) Maximum (mS/m) Average (mS/m) SD (mS/m) Medium channel Cenozoic alluvium 30.05 136.03 71.38 28.71



Deep channel Cenozoic alluvium 40.30 127.03 84.40 28.48




Figure 6.1: Stratigraphic log and borehole wireline rock properties for Boundary Bore (GW020767) redrill.


7 Acknowledgements

Geoscience Australia and its project partners, the Geological Survey of New South Wales and the Geological Survey of Queensland, gratefully acknowledge the following organisations and people:

• Landholder Bruce Hearn of Euroli Station

• Traditional owners the Barkandji People for cultural heritage monitoring

• DRC Drilling Pty Ltd, Dubbo NSW

• Fox Drilling Services Pty Ltd (Fox Campbell, licensed waterbore driller) for overseeing drilling operations through the Great Artesian Basin and ensuring the technical success of boreholes

• Greg Swain and Daniel Gray (Geoscience Australia On-site Representatives) for in-field management of drilling activities and budget monitoring

• Reviewer: Tim Barton

• OPM Consulting Pty Ltd for cultural heritage clearance work with the traditional owner cultural heritage monitors

• Southern Thomson Project team:

o Geoscience Australia: Angela O’Rourke (Project Manager), Narelle Neumann (former Project Manager), Tim Barton (former Acting Project Manager), Sheree Armistead, Patrice de Caritat, David Champion, Michael Doublier, James Goodwin, David Huston, Subhash Jaireth, Sharon Jones, Peter Maher (EASS, for assistance with land access and cultural heritage clearances), David McInnes, Andrew McPherson, Malcolm Nicoll, Ian Roach (Activity Leader), Paul Rossiter (Contracts and Probity), Roger Skirrow, Matilda Thomas, John Wilford, Geoscience Australia Laboratory and Science Services staff for support and analyses.

o GSNSW: Astrid Carlton, Chris Folkes (Activity Leader), John Greenfield, Phil Gilmore, Rosemary Hegarty (former Activity Leader), Bob Musgrave, Ned Stolz.

o GSQ: Dominic Brown, Paul Donchak, Laurie Hutton, David Purdy (Activity Leader), Janelle Simpson, Ian Withnall.

• Joel Fitzherbert and Mark Eastlake from the GSNSW are thanked for their assistance with thin-section examinations.


8 References

Brodie, R. C., Ley-Cooper, Y., Crowe, M. C. A., McInnes, D. J. and Roach, I. C., in prep. The 2016 Southern Thomson AEM Survey: Southern Thomson Project. Geoscience Australia, Canberra. Record.

Cross, A. J., Doublier, M., Purdy, D. J. and Hegarty, R., in prep. SHRIMP U-Pb ages from the Southern Thomson Project boreholes. Geoscience Australia, Canberra. Record.

Goodwin, J. A., Jiang, W., Czarnota, K., Meixner, T., McAlpine, S. R. B., Buckerfield, S., Nicoll, M. and Crowe, M., 2017. Estimating Cover Thickness in the Southern Thomson Orogen - Results from the pre-drilling application of refraction seismic, audio-magnetotelluric and targeted magnetic inversion modelling methods on proposed borehole sites. Geoscience Australia, Canberra. Record 2017/021, 123 pp. Online: https://d28rz98at9flks.cloudfront.net/111363/Rec2017_021.pdf.

Hawke, J. M. and Cramsie, J. N., 1984. Contributions to the geology of the Great Australian Basin in New South Wales. Geological Survey of New South Wales Bulletin 31, NSW Department of Mineral Resources, Sydney, 295 pp.

Lau, I. C., leGras, M. and Laukamp, C., in prep. Southern Thomson Orogen Mineral Spectroscopy. CSIRO, Perth.

Mason, P. and Huntington, J. F., 2012. HyLogger 3 components and pre-processing: An overview. Northern Territory Geological Survey, Darwin, Technical Note 2012-002.

National Uniform Drillers Licensing Committee, 2011. Minimum construction requirements for water bores in Australia Third edition. National Water Commission, Canberra, Ed Third. Online: http://aditc.com.au/wp-content/uploads/2014/06/Minimum-Construction-Req-Ed-3-2.8MB.pdf.

Pontual, S., Merry, N. and Gamson, P., 2008. Spectral Interpretation Field Manual – G-MEX©. AusSpec International Ltd, Ed 3, Vol 1.

Purdy, D. J., Hegarty, R. and Doublier, M., 2018. Basement geology of the southern Thomson Orogen. Australian Journal of Earth Sciences. Available at: https://doi.org/10.1080/08120099.2018.1453547.

Purdy, D. J., Hegarty, R., Doublier, M. and Simpson, J., 2014. Interpreting basement geology in the southern Thomson Orogen. In: Proceedings of the Australian Earth Sciences Convention 2014, Newcastle, Australia. Geological Society of Australia.

Roach, I. C. (editor) 2015. The Southern Thomson Orogen VTEMplus® AEM survey: Using airborne electromagnetics as an UNCOVER application. Geoscience Australia, Canberra. Geoscience Australia Record 2015/29. Available at http://www.ga.gov.au/metadata-gateway/metadata/record/83844.

Roach, I. C., Brown, D. D., Purdy, D. J., McPherson, A. A., Gopalakrishnan, S., Barton, T. J., McInnes, D. J. and Cant, R., 2017. GSQ Eulo 1 borehole completion record. Geoscience Australia - Geological Survey of Queensland, Canberra. Geoscience Australia Record 2017/07 - Queensland Geological Record 2017/03, 55 pp.

Senior, B. R., Ingram, J. A. and Senior, D., 1969. The geology of the Quilpie, Charleville, Toompine, Wyandra, Eulo and Cunamulla 1:250,000 sheet areas, Queensland. Bureau of Mineral Resources, Geology and Geophysics Record 1969/13, Bureau of Mineral Resources, Geology and Geophysics Canberra.

Wallis, G. R. and McEwan, P. R., 1962. Yantabulla 1:250,000 Geological Series Sheet SH/55-05. Geological Survey of New South Wales Sydney. 1st edition.

http://aditc.com.au/wp-content/uploads/2014/06/Minimum-Construction-Req-Ed-3-2.8MB.pdf

http://www.ga.gov.au/metadata-gateway/metadata/record/83844


Appendix A Borehole construction

The Euroli 1 borehole was constructed using a combination of mud rotary drilling to refusal into competent basement, then diamond drilling the core tail. Drilling commenced with a 76.0 m DL vertical section of mud rotary drilling using a 215.90 mm (8½ inch) diameter polycrystalline diamond (PCD) mud rotary drill bit and installation of 76 m of 168.28 mm OD (6 5/8 inch) casing to prevent loose surface material from collapsing into the hole. This was cemented into place. The borehole was deepened to 83 m DL into competent basement rocks using a 149.23 mm (5 7/8 inch) PCD mud rotary drill bit and cased using 114.30 mm OD (4 ½ inch) SFJ screw-thread casing, which was not cemented into place and was removed prior to abandoning the hole. Drilling then continued into basement using a 96 mm OD HQ3 diamond drill bit and 3.0 m triple-tube core barrel to 121.0 m DL, where the rocks were deemed to be competent enough for the insertion of a Hall-Rowe wedge. This was used to deviate the borehole and allowed for structural measurements on subsequent diamond drill core. The borehole was then drilled to the EOH at 153.7 m DL.

The borehole was abandoned by removing the SFJ casing and progressively cementing the borehole from bottom to top in stages through the HQ3 drill pipe to surface. The casing was cut off 0.5 m below surface and the borehole was rehabilitated by pushing surface soil back over. The drilling mud sumps were fenced, left to dry out and were rehabilitated by the landholder by pushing the original surface soil back into the sumps.

Drilling equipment consisted of a Sandvik DE880 multi-purpose drilling rig, a National Oilwell skid-mounted mud pump, 20’ mud tank, jack-up rod sloops, 40’ mobile workshop/office/first aid room, lighting towers and support vehicles.


Figure 8.1: Euroli 1 borehole construction.


Appendix B Drilling activities and consumables

Table 8.1: Euroli 1 drilling times and production rates.

Date Plod # Shift Hole Rotary Mud Diamond Both

From

To

Tota

l

From

To

Tota

l

Dril

ling

Tim

e

Tota

l act

ive

time

Tota

l ina

ctiv

e tim

e

Tota

l non

-ch

arge

able

tim

e

Tota

l shi

ft

m m m m m m hrs hr hr hr hr

Total 83.0 70.7 45.80 42.30 36.50 31.50 156.00

Thursday, 13 July 2017 302128 Night Euroli 1 12.00 12.00

Friday, 14 July 2017 302129 Day Euroli 1 0.50 11.50 12.00 Friday, 14 July 2017 302130 Night Euroli 1 0.0 18.0 18.00 3.5 8.00 0.50 12.00

Saturday, 15 July 2017 302131 Day Euroli 1 18.0 76.3 58.30 6.5 3.00 1.50 1.00 12.00 Saturday, 15 July 2017 302132 Night Euroli 1 8.00 2.00 2.00 12.00

Sunday, 16 July 2017 302133 Day Euroli 1 12.00 12.00 Sunday, 16 July 2017 302134 Night Euroli 1 76.3 83.0 6.70 1 1.50 9.50 12.00 Monday, 17 July 2017 302135 Day Euroli 1 83 92.6 9.60 6.5 4.00 1.50 12.00 Monday, 17 July 2017 302136 Night Euroli 1 92.6 105.3 12.70 7.75 3.75 0.50 12.00

Tuesday, 18 July 2017 302137 Day Euroli 1 105.3 120.7 15.40 4.5 5.00 2.00 0.50 12.00 Tuesday, 18 July 2017 302138 Night Euroli 1 120.7 120.7 5 1.00 6.00 12.00

Wednesday, 19 July 2017 302139 Day Euroli 1 120.7 152 31.30 10 1.00 1.00 12.00 Wednesday, 19 July 2017 302140 Night Euroli 1 152 153.7 1.70 1 6.50 3.50 1.00 12.00


Table 8.2: Euroli 1 drilling consumables used.

165

mm

(6 5

/8 S

FJ)

Dar

by P

lug

Dar

by P

lug

Aus

-Gel

Xtr

a (b

ento

nite

)

Soda

Ash

Cem

ent

AM

C P

ac-L

AM

C P

ac-R

Aus

-Det

Xtr

a

Cla

y D

oc

Torq

ue G

uard

Xan

Bor

e

XT R

od G

reas

e

/ m 6 5/8 HQ 25 kg 25 kg 20 kg 25 L 25 kg 25 L 10 kg 25 L 17 kg

Total 76 1 1 19 1 161 0 3 4 2 3 1 1

Thursday, 13 July 2017 302128 Night Euroli 1 2 1 1

Friday, 14 July 2017 302129 Day Euroli 1 15 1 1 1

Friday, 14 July 2017 302130 Night Euroli 1

Saturday, 15 July 2017 302131 Day Euroli 1 1 1 1 1

Saturday, 15 July 2017 302132 Night Euroli 1 76 1 85

Sunday, 16 July 2017 302133 Day Euroli 1

Sunday, 16 July 2017 302134 Night Euroli 1

Monday, 17 July 2017 302135 Day Euroli 1 1 1

Monday, 17 July 2017 302136 Night Euroli 1

Tuesday, 18 July 2017 302137 Day Euroli 1 1 3

Tuesday, 18 July 2017 302138 Night Euroli 1 1 1 1

Wednesday, 19 July 2017 302139 Day Euroli 1 1 1

Wednesday, 19 July 2017 302140 Night Euroli 1 73 1


Appendix C Petrophysical equipment details

C.1 Borehole wireline logging equipment • Mt Sopris QL40 IND dual induction tool SN 6067, 50 cm (medium) and 80 cm (deep) coil

spacing

• Mt Sopris QL40 GRA natural gamma tool SN 6060

• Mt Sopris QL40 MS magnetic susceptibility tool SN 144804

• ALT Matrix data acquisition system SN 0D0D

• Auslog W2000-4 winch SN T199 with 1750 m of 4-conductor cable.

C.2 Hand-held magnetic susceptibility logging equipment • CoRMaGeo RT-1 magnetic susceptibility meter SN 1520239 (GA).

C.3 Analytical balance equipment (density determination) • A & D Instruments EP-41KA Industrial Balance, quoted accuracy ± 1.0 g. Last calibrated 20

September 2017.


Appendix D Petrophysical data acquisition and processing

D.1 Data acquisition and processing Borehole wireline petrophysical data were acquired during the mud rotary and diamond drilling operations, nominally in the open borehole as each section of the borehole was drilled and before steel casing was inserted. Data from each logging run in the borehole were assessed for quality and were then stitched together to create a final run of data for the length of the borehole where possible.

Table 8.3: Borehole wireline data acquisition steps in Euroli 1

Date Length logged (m DL)

Borehole casing size Properties logged

15.07.2017 0-76.0 m DL 215.9 mm open hole to 76.5 m DL Natural gamma, induction conductivity

19.07.2017 0-153.3 m DL 168.28 mm OD steel to 76.5 m DL, then 96 mm open hole to 153.7 m DL

Natural gamma, induction conductivity

Hand-held magnetic susceptibility data were acquired in the field along the entire length of the borehole from the mud rotary drilled chips at 1.0 m intervals and from the diamond drill core at 0.5 m intervals. These data were used to produce a final magnetic susceptibility log of the borehole. Measurements were made on mud rotary drilled chip samples by placing the sample vial on top of the magnetic susceptibility meter and repeatedly measuring the sample to obtain a repeatable value. For magnetic susceptibility measurements on diamond drill core the plastic diamond drill core trays used for the drilling program were elevated above the work tables on a stack of two empty core trays to ensure no interference from steel in the work tables. Point observations were then obtained at 0.5 m intervals by repeated measurements on the same point to obtain a repeatable value. Magnetic susceptibility measurements on core were multiplied by the recommended compensation factor for the core size according to the manufacturer’s instructions.

D.2 Equipment calibration Borehole wireline tools were calibrated according to the manufacturer’s Standard Operating Procedures (SOPs) described in the user manuals, also described in Roach et al. (2017), apart from the natural gamma tool which was calibrated in the factory and is not capable of being calibrated in the field. In the field equipment was connected to the ALT Matrix data acquisition system and energised for a period of at least 15 minutes in the borehole to equilibrate temperature with the bore fluid before commencing calibration. Equipment was fully tested in Canberra before commencing borehole wireline logging operations to ensure that it was stable and gave repeatable results prior to the field campaign, and calibration drift was checked in the field at every use to ensure data repeatability.

The primary handheld magnetic susceptibility meter used to obtain data on mud rotary drilling chips and diamond drill core (CoRMaGeo RT-1 SN1520239) was calibrated by the manufacturer before commencing the field operations.


D.3 Data processing Petrophysical data were processed using the following processing stream:

• Levelling raw borehole wireline data files to a common datum (ground level) and interpolating the sampling interval to even increments (0.05 m) using WellCAD.

• Combining data from different logging runs into a single data file and removing overlapping data.

• Removing spikes or bad data in induction conductivity and magnetic susceptibility data caused by steel casing and inserting null values.

• Bridging any single-sample data dropouts caused by transient telemetry errors during acquisition by averaging data across the gap, leaving larger data gaps between successive logging runs as nulls.

• Editing natural gamma data to remove the effects of gamma-ray attenuation due to casing and changes in borehole diameter in overlapping data from earlier and later logging runs by applying a bias to attenuated data to achieve a full run of apparent “open hole” natural gamma data.

• Editing handheld magnetic susceptibility data to remove the effects of verified steel particle contamination.

• Produce a final LAS-format data file of:

o Open hole natural gamma

o Medium- and deep-channel induction conductivity (including data gaps)

o Handheld magnetic susceptibility.


Appendix E Euroli 1 Lithological and stratigraphic log

FROM TO GA LITHOLOGY

GA QUALIFIER COLOUR Munsell colour

DESCRIPTION Grain size PROVINCE STRATNAME MAPSYMBOL

m TVD = DL m TVD = DL

Cla

y

Silt

Vfin

e

Fine

Med

Coa

rse

Vcoa

rse

Gra

nule

Pebb

le

Cob

ble

0.00 2.00 Aeolian Rd-br 2.5 YR 4/6 Red-brown fine sand and silt. Windblown soil low in organic content

X X No province Quaternary dunes Qd

2.00 5.00 Gravelly clay mottled Cr-br-rd-beige

5YR 6/6 Dominantly mottled cream-brown-red-beige clay with gravelly fragments

X X X No province Cenozoic alluvium Cz

5.00 12.00 Gravelly clay mottled, ferruginous, manganiferous

Cr-rd-bn 2.5YR 4/6 Cream-red-brown mottled, partially indurated hardpan with regolith carbonate coatings in veins, subrounded ferruginous fragments, manganiferous coatings on veins and partings and fine-grained quartz chips


12.00 19.00 Silty sandstone mottled, ferruginous, manganiferous

Beige-cream-rd-bn

5Y 8/2 Fine-grained sandstone with siltstone chips, beige-cream colours with manganiferous vein coatings and ferruginised quartz chips


19.00 29.00 Sandy siltstone mottled, ferruginous, manganiferous

Gy-pur-rd-br-cream-pnk

10R 4/1 Grey-purple-red-brown-cream-pink mottled shale with fine-grained angular quartz fragments, manganiferous and ferruginous coatings on partings


29.00 55.00 Claystone mottled, ferruginous

Wh-cream Puggy white-cream coloured, plastic clay with ferruginous mottles, becoming cream-purple at base. Base of surface weathering at ~ 55 m

1 Eromanga Basin Wallumbilla Formation Klu

55.00 74.00 Claystone carbonaceous Lt gy-gy Gley2 3/1 Puggy, slimy light grey to mid-grey clay with minor hard claystone bands and darker carbonaceous clay bands

X Eromanga Basin Wallumbilla Formation Klu

74.00 78.00 Gravel Lt gy-gr-dl gy

Gley2 3/1, gley1 4/1

Dark green-grey gravel with lithic fragments and framboidal pyrite < 4 mm diameter in the top 1 m. Lithic fragments are platy, smooth and worn. Some platy, smooth, worn, quartz fragments are also present

X X X X X X Eromanga Basin Wyandra Sandstone Member Klws

78.00 153.70 Schist gy Gley1 4/1 Grey, banded, laminated, spotted schist and minor interbedded sandstone

X X X X X Thomson Orogen


Appendix F Deviation survey

Deviation survey by Reflex EZ TRAC. Diamond drill core orientation by Reflex ACT III RD core device.

Table 8.4: Deviation survey data for Euroli 1.

Length Azimuth Inclination Hade Magnetic field

Notes

m DL Degrees magnetic

Degrees* Degrees nT

0.0 0.0 -90.0 0.0 Mast orientation

120.0 92.2 -89.6 0.4 58870 Wedge set at 115 m

126.0 51.7 -88.0 2.0 55759

153.7 56.3 -88.6 1.4 55364 EOH

*Inclination: degrees from horizontal, negative downwards


Appendix G Borehole log

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0 Qs

Cz

Klu

Klws

Bas

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

TVD(m)

Natural gamma(API)

300

200

100

0

Medium induction(mS/m)

1900

1400

900

400

-100

Deep induction(mS/m)

1900

1400

900

400

-100

Magneticsusceptibility

(SI x 10-5)

1500

1000

500

0

Bor

ehol

eco

nstru

ctio

n

Lithology StratigraphyDL(m)

Euroli 1Longitude / easting: 144.350053° / 242345 mLatitude / northing: -29.199833° / 6766966 mDatum: GDA94 / MGA94Z55S

Location: 23 km SSW of Hungerford, QueenslandOperator: Geoscience Australia for the Geological Survey of New South Wales

Date completed: 20.07.2017Borehole orientation: Vertical, wedgedAHD elevation (AUSGeoid2020): 97 m

Stratigraphy

Qs - Quaternary sand

Cz - Cenozoic alluvium

Kw - Winton Formation

Klu - Wallumbilla Formation

Klws - Wyandra Sandstone Member

Bas - Basement

Lithology

Carbonaceous claystone

Claystone

Ferruginous clay and calcrete

Gravelly clay

Lithic sandstone

Red-brown fine sand and silt

Schist

Siltstone

Silty sandstone

Cement

Casing

Open hole

WedgeWedge

Construction

Sur

face

wea

ther

ing

Pal

aeow

eath

erin

g

euroli 1 borehole completion record · 2018. 5. 14. · euroli 1 borehole completion record...

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