Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Investigator Resources Limited Suite 48, Level 3, Benson House 2 Benson Street, Toowong, Qld 4066 Tel: +61 (0)7 3870 0357 Fax: +61 (0)7 3876 0351
Email: [email protected] web: www.investres.com.au
EPM 16511
BRODIES LOOKOUT
SURRENDER AND FINAL REPORT
for period
27 April 2009 to 26 April 2011
D G Jones and B R Willott Investigator Resources Limited 6 September 2011
Page | 1 Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
2 TABLE OF CONTENTS
3. SUMMARY ...... 4 4. INTRODUCTION ...... 5 4.1. TENURE ...... 5
4.2. LOCATION ...... 6 4.3. LOCAL ACCESS ...... 7 4.4. EXPLORATION RATIONALE ...... 8 4.5. PROGRAM UNDERTAKEN ...... 10 4.6. PREVIOUS EXPLORATION ...... 10 5. GEOLOGY ...... 12
5.1 REGIONAL GEOLOGY ...... 12 5.2. LOCAL GEOLOGY ...... 14 5.2.1. Proterozoic ...... 15 5.2.2. Mesozoic (Rolling Downs Group) ...... 15 5.2.2.1. Gilbert River Formation (JKg) ...... 15 5.2.2.2. Wallumbilla Formation (Ranmoor Member) (Klu) ...... 17 5.2.2.3. Toolebuc Formation (Klo) ...... 17 5.2.2.4. Allaru Mudstone (Kla) ...... 17 5.2.2.5. Floraville Formation (Klf) ...... 17 5.2.3. Structure ...... 18 6. EXPLORATION UNDERTAKEN ...... 18 7. CONCLUSIONS ...... 22 8. RECOMMENDATION ...... 22 9. REFERENCES ...... 23 APPENDIX 1 ...... 24
QDEX REPORTS ...... 24 APPENDIX 2 ...... 25
WATER BORES ...... 25 APPENDIX 3 ...... 26
MRX PTY LTD DRILL HOLE DATA ...... 26
Page | 2
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figures FIGURE 1. EPM 16511 SUB-BLOCKS ...... 5 FIGURE 2. LOCATION AND ACCESS TO EPM 16511 ...... 6 FIGURE 3. LOCAL TOPOGRAPHY, EPM 16511 ...... 7 FIGURE 4. ACCESSIBLE TRACKS, GROUND COVER AND TOPOGRAPHY ...... 8 FIGURE 5. REGIONAL TOTAL COUNT RADIOMETRIC IMAGE (WHITE = STRONGEST RESPONSE) ...... 9 FIGURE 6. EPM 16511 IN RELATION TO MT ISA INLIER ...... 12 FIGURE 7. CHRONOSTRATIGRAPHIC CHART FOR THE MT ISA SUCCESSION IN THE VICINITY OF EPM 16511 ...... 15 FIGURE 8. LOCAL GEOLOGY, EPM 16511 ...... 16 FIGURE 9. CHRONOSTRATIGRAPHY AND LEGEND FOR FIGURE 8 ABOVE ...... 16 FIGURE 10. CHARACTER SAMPLING, TOOLEBUC FORMATION ...... 18 FIGURE 11. LOCATION OF CROSS-SECTIONS ...... 19 FIGURE 12. SECTION C-D ...... 20 FIGURE 13. SECTION E-F ...... 21 FIGURE 14. SECTION G-H ...... 21 FIGURE 15. SECTION J-K ...... 22
Tables TABLE 1. EPM 16511 SUB-BLOCKS ...... 5
Page | 3
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
3. SUMMARY
Many of the granitic suites in the Mt Isa Inlier are anomalously high in uranium. Groundwater flowing out from the Mt Isa Inlier may carry oxidised uranium as a complex uranyl carbonate ion. Specific permeable units within the Mesozoic strata of the Great Australian Basin (formerly known as the Great Artesian Basin) carry most of the groundwater flowing to the south and east of the Mt Isa Inlier. Precipitation of uranium could occur if the migrating groundwater encountered reducing conditions such as the carbonaceous horizons found in the Mesozoic Toolebuc Formation.
EPM 16511 targeted Toolebuc Formation mapped southwest of Nardoo homestead, located 200km due north of the city of Mt Isa.
Reconnaissance traversing of EPM 16511 was carried out in August 2009. The objective was to verify that outcropping Toolebuc Formation was present. A detailed compilation of water bore data and previous exploration was completed.
In November 2010 Southern Uranium Limited (ASX Code SNU) changed the name of the Company to Investigator Resources Limited (ASX Code IVR), reflecting a broader multi-commodity approach to its exploration strategy. This name change was then formalised by ASIC and Investigator Resources commenced trading on the ASX on 26 November 2010. Due to budget constraints and the low priority of EPM 16511 Investigator Resources Limited lodged an Application for Surrender of EPM 16511 tenure on 21 March 2011 that was accepted by the Department of Employment, Economic Development and Innovation (DEEDI) on 19 July 2011. The surrender coincides with the end of Year 2 and includes all 100 sub-blocks for EPM16511.
Page | 4
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
4. INTRODUCTION
4.1. Tenure EPM 16511 was surrendered by Investigator Resources Limited on 21 March 2011 coinciding with the end of Year 2. The area surrendered comprised all 100 sub-blocks originally granted to Southern Uranium Limited (100%) on 27 April 2009.
EPM 16511 was originally granted to Southern Uranium Limited for a period of five (5) years. The tenement was due to expire on 26 April 2014. The expenditure commitment for Year 1 and Year 2 (combined) is $110,000. At the end of Year 2, the tenement size was due to be reduced by 50%.
BLOCK 2467 SUB-BLOCKS g, h, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z BLOCK 2468 SUB-BLOCKS f, g, h, j, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z BLOCK 2469 SUB-BLOCKS q, v, w BLOCK 2539 SUB-BLOCKS a, b, c, d, e, u, z BIM NORM BLOCK 2540 SUB-BLOCKS a, b, c, d, e, f, g, h, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z BLOCK 2541 SUB-BLOCKS a, b, c, f, g, h, l, m, n, o, q, r, s, t, u, v, w, x BLOCK 2611 SUB-BLOCKS e BLOCK 2612 SUB-BLOCKS a, b BLOCK 2613 SUB-BLOCKS a, b, c, d, h, j
Table 1. EPM 16511 Sub-blocks
Figure 1. EPM 16511 Sub-blocks
Page | 5
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
4.2. Location Brodies Lookout is centred 200km due north of Mt Isa. Bitumen highways link Mt Isa via Cloncurry to the coastal city of Townsville to the east, the city of Darwin via Tennant Creek to the west, and the city of Brisbane via Longreach to the southeast.
Figure 2. Location and access to EPM 16511
From Cloncurry, the sealed Burke Developmental Road is followed north for 185km to the Four Ways Roadhouse, and then the sealed Wills Development Road northwest for 92km to the turnoff to Nardoo homestead. The journey takes 3 hours. Fuel is available at the Four Ways Roadhouse. Most of the tenement falls within the “Augustus Downs” 1:100,000 sheet 6860. The local topographic features are illustrated below. The latitude and longitude are MGA94. Spot heights are shown in metres.
Page | 6
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 3. Local topography, EPM 16511
The area is drained by the north-easterly flowing Gidya Creek, Soda Creek, Whistlers Creek and Mittagudi Creek, which are tributaries of the Leichhardt River. The tenement covers a plain ranging from 55m to 100m above sea level, covered mainly with Mitchell grass.
4.3. Local Access Within the tenement, access is variable, with station tracks and fence lines the principal means for vehicular travel. The few station tracks on black soil are impassable after rain. The land use is cattle grazing. The figure below, compiled from aerial photography, illustrates the physiography. Accessible 4-wheel drive tracks are shown in red. Triangles are spot elevations; contours are shown in white.
Page | 7
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 4. Accessible tracks, ground cover and topography
4.4. Exploration Rationale The Mt Isa Inlier contains some 178 recorded uranium occurrences. Some are of major significance, including the historic Mary Kathleen mine and the Skal and Valhalla deposits. Many of the granitic suites in the Mt Isa Inlier are anomalously high in uranium. Groundwater flowing out from the Mt Isa Inlier may carry oxidised uranium as a complex uranyl carbonate ion. Specific permeable units within the Mesozoic strata of the Great Australian Basin (formerly known as the Great Artesian Basin) carry most of the groundwater flowing to the south and east of the Mt Isa Inlier. Precipitation of uranium could occur if the migrating groundwater encountered reducing conditions such as the carbonaceous horizons found in the Mesozoic Toolebuc Formation.
Page | 8
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 5. Regional total count radiometric image (white = strongest response) Bright green shows Toolebuc Formation outcrops.
The regional total count radiometric image (Figure 5 above) shows drainage from the radiometrically "hot" Weberra Granite and Bigie Formation, outcropping 25km SW of EPM 16511, passing directly over outcrops of Toolebuc Formation. Field relationships suggest that the Bigie Formation, a red-bed conglomerate and sandstone sequence, is coeval with, or immediately preceded, the 1710 Ma intrusion of the Weberra Granite (Neumann et al, 2006).
The Toolebuc Formation here comprises two main litho-facies each about 15-20m thick. The upper shelly limestone unit contains layers rich in pyritic black shale while the lower calcareous bituminous marine shale contains kerogen-rich pyritic oil shales with intercalated limestone. Individual facies vary in thickness over relatively short distances. The Toolebuc Formation is moderately permeable and confined above and below by impermeable siltstones and mudstones.
In the vicinity of EPM 16511, reconnaissance mapping indicates that only the lower unit of the Toolebuc Formation is exposed at surface. This consists of a thin (<10cm) shaly coquinite underlain by a basal pinkish fossiliferous limestone containing fish scales and coprolite, underlain by shales containing common round football-sized concretions of limestone. Information from water bores and previous drilling indicates that the Toolebuc Formation dips gently to the northeast.
Uranium values in excess of 200ppm U3O8 were recorded by the Bureau of Mineral Resources in cuttings from water bores drilled into the Toolebuc Formation (Tucker, 1975). Additional contribution from uranium-bearing oxidised groundwater depositing uranium within the Toolebuc Formation could raise the uranium content to ore grade.
Page | 9
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
The proposed programme for Year 1 was as follows:
Activity Time Budget A$ (weeks) Review of past exploration and available geophysical data 2 $ 5,000 Water sampling of existing water bores 4 $ 5,000 High-resolution airborne geophysics to delineate paleo- 2 $20,000 drainage and deltaic environments for U targets and assess basement potential for base metals gold (uranium) IOCGU style. Outcrop prospecting/sampling 1 $10,000 Review & report 1 $ 5,000 Total: 10 $45,000
4.5. Program Undertaken Previous company exploration reports were reviewed, together with available geophysical data. Relevant published maps, reports and journal articles were also reviewed. Water bore logs from the registered bores located in the vicinity of EPM 16511 were obtained from the Department of Natural Resources and Water (“DNRW”) and reviewed.
A one-day field reconnaissance visit was made to verify the presence of Toolebuc Formation. Outcrops were located inside the western boundary of the tenement and some character samples taken (see Figure 5).
4.6. Previous Exploration Prior to the 1950s, exploration in the region of Brodies Lookout was confined to outcropping Proterozoic basement rocks of the Mt Isa Inlier. In 1954, Frome-Broken Hill Pty Ltd (a wholly-owned subsidiary of Consolidated Zinc Limited) began regional geological mapping of the Carpentaria Basin, supplemented by ground gravity and aeromagnetic surveying in 1955-56. Two stratigraphic wells were drilled, at Weipa and Wyaaba, in 1957. No oil or gas was detected.
In 1958 the Bureau of Mineral Resources (“BMR”) ran a series of seismic refraction profiles across the southern margin of the Carpentaria Basin, and Associated Australian Oilfields Ltd (“AAO”) drilled an unsuccessful oil bore at Karumba. The Delhi-Santos group conducted aeromagnetic surveys over the entire Carpentaria Basin in 1962, followed by Mid-Eastern Oil NL who focused on the southern margin of the Basin. Mid-Eastern drilled Normanton No.1 and Burketown No.1 wells in 1963-64.
In 1966, Sumatra Oil Corporation was granted a permit to explore 186,500 sq km along the southern part of the Carpentaria Basin. No work was recorded.
From 1969 to 1974, the BMR in conjunction with the Geological Survey of Queensland (“GSQ”) drilled 23 stratigraphic holes in the Carpentaria Basin.
Authority to Prospect (“AP”) 1325M was granted to Amax Exploration (Australia) Inc (“Amax”) in Dec 1973, and although the objective was to explore for Mt Isa-style deposits, the tenement also covered the Mesozoic rocks within the present EPM 16511. Geochemical sampling failed to detect any significant mineralisation and the tenement was relinquished at the end of 1974.
MRX Pty Ltd was granted 7 APs in the Brodies Lookout area in 1980, and drilled 26 reconnaissance drill holes in 1981 to explore the oil shale potential of the Toolebuc Formation. Only 8 reached target
Page | 10
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout” depth and the samples from 2 holes were destroyed in transit from Mt Isa to Brisbane. The drill could not penetrate the Cainozoic gravel cover, which was up to 10m thick in places. The oil yields were estimated at around 50 litres/tonne, which MRX considered too low to be economic, and the tenements were relinquished in late 1981.
AP 295P covering the entire Carpentaria Basin was issued to Balladoran Investments Pty Ltd in May 1981. The tenement was farmed out to Planet Resources Group NL (“Planet”) in Jan 1982.
Amoco Australia Petroleum Company (“Amoco”) was granted AP 327P in the Lawn Hill area in Sep 1982. The permit covered 16,750 sq km. Five core holes were drilled to average depths of 600m to test the source and reservoir quality of the McNamara, Fickling and South Nicholson Groups.
EPM 1581 was granted to Dampier Mining Company Ltd in October 1975 to explore for stratabound copper deposits in the Paradise Creek Formation, Gunpowder Creek Formation and Myally Subgroup in the north-west comer of the Dobbyn 1:250,000 Sheet area. This Permit also extended into the Camooweal 1 :250,000 Sheet area. Exploration included geological mapping, rock chip sampling, and percussion drilling at the Boomerang and Valparaisa prospects in the Camooweal 1 :250 000 Sheet area; only geological mapping was carried out in the Dobbyn Sheet area. The Permit was relinquished in October 1976.
EPM 9222 was granted to BHP Minerals Pty Ltd (“BHP”) in January 1993 to explore for sediment- hosted Pb-Zn-Ag and Mount Isa-style Cu mineralisation in the Gunpowder Creek Formation. Part of this Permit was in the Donors Hill 1:250,000 Sheet area. The company carried out a literature review of previous exploration and a regional soil sampling program. The samples were assayed for Cu, Pb, Zn, Fe and Mn. Maximum assay results recorded were 94ppm Cu, 39ppm Pb, 44ppm Zn, 2% Fe, and 300ppm Mn. A shallow RAB drilling program was abandoned after drilling 34 holes, with only 5 holes reaching the Proterozoic basement. Samples of basement rocks from the drilling program were assayed for Cu, Pb, Zn, Ag, As, Fe, Mn, Cd, Co, Cr, Mo, Ni, V, P and Bi.
Phelps Dodge Australasia Pty Ltd was granted EPM 12756 “Augustus Downs” in July 2003. The tenement was transferred to Red Metal Limited in Oct 2003. The target was sediment-hosted copper deposits of the Mt Gordon type. A reconnaissance helicopter assessment of areas highlighted from re-interpretation of previous EM data was conducted. No further exploration was considered warranted and the tenement was surrendered.
EPM 15043 “Myally Creek”, located immediately south of EPM 16511, was granted for a period of five years to Superior Resources Limited commencing in Mar 2006. The project area was considered prospective for copper, lead, zinc and silver as rocks in the area are possible equivalents to those that host the Mount Isa copper and lead-zinc-silver deposits. A number of significant airborne radiometric uranium anomalies were apparent from the MIM airborne radiometric survey in the Lagoon Creek area. The anomalies corresponded with mapped areas of Toolebuc Formation. A soil sampling survey was completed over the best two uranium anomalies on the eastern side of Lagoon Creek. The best results returned uranium up to 24.3 ppm and molybdenum up to 92.8 ppm. Eight outcrop samples collected from the two areas returned uranium contents ranging from 183 ppm to 325ppm U3O8. Drilling of 52 drill holes for 2596m at the Lagoon Creek Uranium Prospect was completed in Jun 2008. The drilling targeted the Cretaceous Toolebuc Formation. Assay results from the drilling indicate that anomalous metal (Ag, Cu, Mo, U, V and Zn) values are associated with the Toolebuc Formation but these are well below economic cut-off values.
Page | 11
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
5. GEOLOGY
5.1 Regional Geology The tenement was anticipated to cover sub-outcropping Cretaceous Toolebuc Formation, surrounding the Mt Isa Inlier. The Mount Isa Inlier is subdivided by major north-striking faults into three broad tectonic belts: the Western Succession, the Kalkadoon-Leichhardt Belt and the Eastern Succession. These are made up of Paleoproterozoic metasediments, volcanics and intrusive rocks.
The Western Succession consists of the Lawn Hill Platform, Leichhardt River Fault Trough and the Myally Shelf. The Kalkadoon-Leichhardt Belt is bounded to the west and east, respectively, by the Quilalar and Pilgrim Fault zones. This belt is made up of the Ewen Block and the Kalkadoon- Leichhardt Block. The Eastern Succession is subdivided into the Wonga Belt in the west, the Quamby-Malbon zone, and the Cloncurry-Selwyn zone in the east.
Figure 6. EPM 16511 in relation to Mt Isa Inlier Toolebuc Formation outcrops in bright green.
Page | 12
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
The basement rocks are a sequence of sedimentary, volcanic and intrusive rocks that were highly deformed during the 1900-1870 Ma Barramundi Orogeny. They are overlain by three cover sequences, which are Paleoproterozoic volcano-sedimentary packages separated by regional unconformities. The cover sequences were deformed and regionally metamorphosed up to upper amphibolite facies during the 1620-1520 Ma Isan Orogeny.
The Mount Isa Inlier has been intruded by granitic batholiths of Paleoproterozoic and Mesoproterozoic age. The Leichhardt River Fault Trough is a paleotectonic trough containing thick sequences of basalt and shallow-water sedimentary rocks now folded, faulted and regionally metamorphosed.
A total of 107 uranium occurrences have been recorded in Paleoproterozoic metasediments of the Leichhardt River Fault Trough. Most of these occurrences are in the Eastern Creek Volcanics; a few minor prospects are in the underlying Leander Quartzite. Brooks (1960) has described the geology and mineralogy of these stratabound prospects, which typically form steeply dipping tabular to pipe- like bodies and are often associated with breccia zones within the host rocks.
In the Leichhardt River Fault Trough, the uranium deposits are metasomatite type deposits, whereas the uranium deposits in the Wonga Belt are metamorphic type deposits (skarn-hosted metamorphic hydrothermal deposits).
Some granite suites within the Mt Isa Inlier are highly anomalous in uranium, and potentially may provide the source for uranium transported out of the Inlier by groundwater, and re-precipitated in suitable reducing environments such as that provided by the Toolebuc Formation.
Carpentaria Basin deposition is considered to have commenced in the Early Jurassic when the sea entered either from the north. Around the Mt Isa Inlier, sedimentation commenced with the spreading of fluvial quartzose sands, equivalent to the Hutton Sandstone of the Eromanga Basin, into basement lows. By the Middle Jurassic, deposition of sands of the Eulo Queen Group (Louth and Hampshire Formations) and its equivalents had commenced.
Throughout most of the Jurassic, sedimentation was concentrated within these basement depressions. A fluvial environment is proposed, the provenance probably being the surrounding basement areas. The presence of these Early and Middle Jurassic sediments contiguous with those of the Papuan and Eromanga Basins suggests that neither the Bramwell nor the Euroka Arches were present at this time, but were probably developed in the Cretaceous. Towards the end of the Jurassic the depressions were filled, and they and the intervening areas were overlain by a blanket of continental followed by shallow marine sandstone and siltstone of the Gilbert River Formation. The fluvial sediments (Yappar Member) derived from uplands of exposed basement rocks around the Basin, continued to blanket large portions of the Basin throughout the Early Cretaceous but gradually gave way in the Middle Neocomian to a marine transgression represented by the upper part of the Gilbert River Formation, the Coffin Hill Member, which is glauconitic in part.
By Early Aptian times the inundation which began in the north in Middle Neocomian times had transgressed most of the basin. Connections are postulated with the Eromanga Basin through a narrow eastern strait in the Euroka Arch and with the Money Shoal Basin across the underlying McArthur Basin rocks and/or the Wessel Rise. Deposition continued through the Neocomian and Aptian and reached a maximum in the Late Aptian where fine grained clastics of the Rolling Downs Group were spread basin-wide, overlapping older basin sediments of the Gilbert River Formation and, along the basin margins, basement. This Neocomian-Aptian transgression was part of a worldwide Cretaceous transgression.
Page | 13
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
The basal Wallumbilla Formation of the Rolling Downs Group was deposited under shallow marine conditions and continued until latest Albian, when the sea finally regressed. Basal glauconitic sands are present in many parts of the Carpentaria Basin, though most of the formation is argillaceous (Doncaster Member) from the latest Aptian, implying a change in provenance, which also occurred in the Eromanga Basin at this time. A volcanic source (postulated as volcanic chains of the east coast of Queensland) is suggested by the presence of montmorillonite clays within the Albian sequence of the Wallumbilla Formation. Locally developed sandstone units in the upper part of the Wallumbilla Formation indicate slight local uplift and regression limited only to a few parts of the basin. In such environments the Trimble Member of the Wallumbilla Formation was deposited in the Carpentaria Basin and a correlative, the Coreena Member, in the Eromanga Basin.
An early Late Albian facies change occurred in both the southern Carpentaria and Eromanga Basins as the thin calcareous oil shale and limestone of the Toolebuc Formation was deposited. The Toolebuc Formation is distinguished from the remaining argillaceous sediments of the Rolling Downs
Group by its high carbonate content (over 50% CaCO3) and its prominent gamma ray anomaly probably due to a high uranium content in the organic material. Areas of Toolebuc deposition on basement highs (Fort Bowen Ridge, Boomarra and Kamileroi Horsts) have given rise to restricted development of massive crystalline coquinite. Farther north the sea was deeper and offshore mud and silt lacking in carbonate were deposited below wave base and the Toolebuc is not represented in these areas.
The Allaru Mudstone overlies the Toolebuc Formation and lithologies similar to those of the Wallumbilla Formation indicate a return to similar depositional environments. The Wallumbilla Formation, Toolebuc Formation and Allaru Mudstone are assigned to the Wilgunya Sub-Group which is the name applied to the equivalent section in the Eromanga Basin.
As the sea withdrew from the entire region during the latest Albian, feldspathic and lithic sand, silt and mud were deposited in both the Carpentaria (Normanton Formation) and Eromanga Basins (Mackunda and Winton Formations) on a broad coastal plain. Sedimentation had ceased in the region during the Cenomanian.
The subsequent history of the Carpentaria Basin has involved widespread weathering and erosion, tilting and burial by Cainozoic strata of the Karumba Basin. Late Cretaceous and Tertiary erosion has removed a great deal of the Jurassic-Cretaceous section especially around the basin margins. Up to 1000m of Carpentaria Basin strata has been interpreted at this stage.
Mid-Tertiary epeirogenic movements near the Euroka Arch led to the establishment of the present drainage patterns towards the Gulf (Carpentaria Basin) and towards the Darling River-Lake Eyre system (Eromanga Basin). The Carpentaria Basin is a simple intracratonic basin which does not appear to have been subjected to substantial compressive folding. The generally gentle dip of the strata to the north is largely depositional locally increased by compaction in pre-Carpentaria Basin depressions or by drape over basement highs.
5.2. Local Geology Within EPM 16511, Proterozoic rocks of the Leichhardt and Calvert Superbasins have been intruded by granite and unconformably overlain by Mesozoic sediments of the northern Eromanga Basin. The Donors Hill and Dobbyn 1:250,000 geological sheets show outcropping Toolebuc Formation covering a much larger area than was found to be the case during reconnaissance of EPM 16511 by Southern Uranium Limited.
Page | 14
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
5.2.1. Proterozoic The basement rocks are dominated by metasediments of the Leichhardt Superbasin, originally deposited in an eastward deepening half-graben and dominated by fluviatile to marginal marine shallow water sequences ranging from quartzite through red beds into carbonates (lowermost Quilalar Formation). Commencing around 1710 Ma, the direction of extension changed from ENE-WSW to NE-SW leading to a rejuvenation of rifting, bimodal volcanism and associated granite intrusions, and development of a new superbasin (Calvert/Isa Superbasin). Half-graben and normal faults formed contemporaneously with this phase of basin evolution trend east-west to WNW-ESE. The chrono- stratigraphy is illustrated in the diagram below.
Figure 7. Chronostratigraphic chart for the Mt Isa succession in the vicinity of EPM 16511
5.2.2. Mesozoic (Rolling Downs Group)
5.2.2.1. Gilbert River Formation (JKg) From water bore and drill hole information the Gilbert River Formation is interpreted to overlie the basement unconformably. Thickness ranges from 40m to 150m. The lithologies comprise quartzose sandstones, conglomerates and minor siltstones.
Page | 15
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 8. Local geology, EPM 16511 Blue squares are water bores.
Ma Era Period Epoch Stage Formation Label Cenozoic Qa TQr Tertiary 35 Paleogene Eocene Floraville KTf
90 Cenomanian Allaru Kla 95 Late Cenomanian Toolebuc Klo Mesozoic 100 Albian Wallumbilla Klu Early 110 Cretaceous Aptian Gilbert River JKg
1680 Torpedo Creek PLt 1690 Surprise Creek PLs 1710 Paleoproterozoic Fiery Creek Volcanics PLf 1711 Weberra Granite 1760 Bigie PLb
Figure 9. Chronostratigraphy and legend for Figure 8 above
Page | 16
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
5.2.2.2. Wallumbilla Formation (Ranmoor Member) (Klu) The Ranmoor Member is seen only as a thick chocolate-brown to black soil cover west of the Toolebuc Formation outcrops. In bores the Wallumbilla Formation is logged as blue to grey shale, siltstone and minor concretionary limestone.
5.2.2.3. Toolebuc Formation (Klo) In the vicinity of EPM 16511, borehole data indicates that the Toolebuc Formation comprises 2 distinct units:
a) An upper coquinitic limestone b) A lower bituminous oil shale with occasional limestone bands
The thickness of each unit varies considerably across the area, probably due to the original irregular surface on which it was laid down. The contact between the two units is usually fairly abrupt and is often marked by a band rich in fish scales.
The upper coquinitic limestone is a distinct bed consisting of recrystallised coquinite and crystalline limestone containing rows of vughs aligned parallel to each other and perpendicular to the bedding. The vughs were considered by previous explorers to be biohermal in origin, the organism once occupying the cavities having been a species of the calcareous hydrozoan Hydractinia. The cavities make the unit highly permeable. Thin bituminous shales are interbedded with the limestone.
Underlying the vuggy limestone is a sequence of calcareous shales. At the top is a 10cm bed of red, buff and purple recrystallised phosphatic limestone containing collophane pellets and fish scales. Underneath is a 10cm bed of grey crystallised limestone and thin interbedded shale with similar collophane pellets, passing down to 10-20cm of recrystallised shell fragments. Whole and fragmented pelecypod shells are common and in many cases have been replaced by pyrite. At the base is a 60cm thick bed of loose uncrystallised coquinite and interbedded shale. All the shale beds are bituminous and have been explored as an oil shale resource.
Beneath the coquinite unit is up to 8m of finely laminated, very fissile, very fine-grained chalky limestone. The lower boundary of the Toolebuc Formation with the Wallumbilla Formation is generally sharp and well defined.
Based on the presence of marine fossils, carbonaceous material and pyrite, a brackish-marine near- shore environment is indicated for the deposition of the Toolebuc Formation.
5.2.2.4. Allaru Mudstone (Kla) The Allaru Mudstone occurs in the central part of the tenement (Figure 8). It is characterised by fossiliferous concretions of impure limestone, with occasional cone-in-cone structures, and interbedded yellow-brown mudstone. It is largely ferruginised and silicified by Tertiary lateritisation. The Allaru Mudstone provides an excellent seal for any hydrological flow in the underlying highly permeable Toolebuc Formation. The upper boundary of the Toolebuc Formation is gradational with the overlying Allaru Mudstone. The change to the Toolebuc Formation is visible in core and cuttings by a darkening in colour and/or an increase in calcite veins, fish scales, shelly fossils, and the commencement of coquinitic limestone bands.
5.2.2.5. Floraville Formation (Klf) The Eocene Floraville Formation unconformably overlies the Allaru Mudstone. It blankets a large proportion of the area and comprises up to 24m thickness of clayey quartz sandstone, conglomerate; minor mudstone and siltstone.
Page | 17
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
5.2.3. Structure The Toolebuc Formation dips to the northeast at 1-2o. Faults in the basement do not appear to have been re-activated post-Paleozoic, as bore data indicates little disruption to the overall planar gently dipping Mesozoic sediments.
6. EXPLORATION UNDERTAKEN A brief reconnaissance visit to EPM 16511 was carried out in August 2009 in conjunction with work undertaken on other EPMs held by Southern Uranium, now Investigator Resources Ltd in the area. The objective was to verify that outcropping Toolebuc Formation was present. This was confirmed and planning for more comprehensive work commenced. A few character samples of outcropping Toolebuc Formation were taken and analysed for U3O8 by XRF. The results are shown in Figure 10 below.
Figure 10. Character sampling, Toolebuc Formation
U3O8 (ppm) assays in yellow; Toolebuc outcrops in bright green.
A detailed compilation of previous exploration was undertaken. An analysis of previous drilling and water bore data was used to plot the intersection of the top and bottom of the Toolebuc Formation
Page | 18
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout” with the base of complete oxidation (“BOCO”). The intersections are illustrated in the following sections. Because of the very shallow dip of the Toolebuc Formation, the vertical to horizontal exaggeration is 100:1. The location of the sections is shown in Figure 11 below. The surface topography is based on Geoscience Australia’s 9-second Digital Elevation Model (“DEM”), cross- checked against 20m contours and spot heights on the 1:100,000 topographic sheets.
Figure 11. Location of cross-sections BOCO-Toolebuc Formation interface projected to surface shown in yellow
Page | 19
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 12. Section C-D
Page | 20
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 13. Section E-F
Figure 14. Section G-H
Page | 21
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
Figure 15. Section J-K
7. CONCLUSIONS • Previous exploration and a current inspection by Southern Uranium/Investigator Resources have demonstrated that the Toolebuc Formation outcrops in the vicinity of EPM 16511 and dips at 1-2o gently to the north and east.
• Surface sampling by Southern Uranium returned values up to 215ppm U3O8.
• The BOCO averages about 32m below surface and represents a potential target zone for further concentration of uranium along the REDOX boundary.
8. RECOMMENDATION A series of shallow (<50m) air core holes should be drilled across the target zone highlighted above, on lines 2km apart with initial hole spacing 200m. The target zone is readily accessible in the dry season.
However, Investigator Resources Limited has reprioritised projects in its portfolio, lowering the priority of EPM 16511. It was decided to apply to surrender the tenure of EPM 16511 to coincide with the end of Year 2. The Application for Surrender of Environmental Forms were lodged on 21 March 2011 and the surrender subsequently accepted by DEEDI on 19 July 2011.
Page | 22
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
9. REFERENCES
Brooks, J.H., 1960. The Uranium Deposits of Northwest Queensland. Geol.Surv.Qld. Pub. No. 297.
Burrows, P.E. and Culpeper, L.G., 2000. Mineral Exploration in the Dobbyn 1:250,000 Sheet Area, North-West Queensland. Geol.Surv.Qld. Record 2002/02, 172p.
Day, R.W., 1969. The Lower Cretaceous of the Great Artesian Basin. In: Campbell, K. S. W. (Ed.) Stratigraphy and Palaeontology: Essays in Honour of Dorothy Hill. Canberra, ANU Press, pp140-3.
Denaro, T.J., Culpeper, L.G., Burrows, P.E and Morwood, D.A., 2004. Mines, Mineralisation and Mineral Exploration in the Cloncurry 1:250,000 sheet area, Northwest Queensland. Geol.Surv.Qld. Record 2004-001.
Foster, D.R.W. and Austin, J.R., 2008. The 1800-1610 Ma Stratigraphic History of the Eastern Succession, Mount Isa Inlier, and Correlations with Adjacent Paleoproterozoic Terranes. Precambrian Research, 163: pp7-30.
Ingram, J.A., 1972. Donors Hill, Qld 1:250 000 Geological Series. BMR Explanatory Notes SE/54-10.
Meyers, M.A., 1969. Carpentaria Basin. Geol.Surv.Qld. Report No.34.
Neumann, N.L., Southgate, P.N., Gibson, G.A. and McIntyre, A, 2006. New SHRIMP geochronology for the Western Fold Belt of the Mt Isa Inlier: developing an 1800 - 1650 Ma event framework. Australian Journal of Earth Sciences, Volume 53, Issue 6, pp 1023 – 1039.
Passmore, V.L., 1979. Carpentaria and Karumba Basins: Explanatory Notes and Stratigraphic Columns. BMR Record 1979/22.
Senior, B.R. and Smart, J., 1973. Oil Traces in the Toolebuc Limestone, Carpentaria and Eromanga Basins, Queensland. BMR Record 1973/6.
Smart, J., 1973. Dobbyn, Qld -1:250 000 Geological Series. BMR Explanatory Notes SE/54-l4.
Page | 23
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
APPENDIX 1
QDEX Reports
Page | 24
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
APPENDIX 2
Water Bores
Page | 25
Investigator Resources Limited: Surrender and Final Report EPM 16511 “Brodies Lookout”
APPENDIX 3
MRX Pty Ltd Drill Hole Data
Page | 26