Murphy Project
Project Summary
Location and Land Status
The Murphy project is located 1000 kilometres from Darwin and 700 kilometres from the town of Mount Isa (Fig 1). Sealed road reaches within 80 kilometres of the property, and the remainder of access is by good gravel roads and station tracks. The project consists of 8 granted tenements covering 9,056 square
kilometres. The project is owned 100% by Bondi Mining Ltd.
The core tenements of the Murphy project were initially acquired in mid-2005 by Global Discovery Pty Ltd (a private company). The tenements were subsequently acquired by Buffalo Gold Ltd (a TSX venture-listed exploration company) through an option deal announced in March of 2006. Bondi Mining Ltd acquired the project in May of 2007 as part of a deal to acquire 100% of Buffalo Gold’s Uranium portfolio.
Figure 01 (above): regional location of the Murphy project.
Target
The Murphy project is highly prospective for high grade unconformity uranium mineralization (Fig 2). The Murphy project lies along strike from the Westmoreland uranium deposits of Laramide resources (Fig 3), and is part of a very active area of uranium exploration. The East Alligator Uranium deposits and the deposits of the Westmoreland area in Queensland are now interpreted to be closely related in terms of their age, uranium sources and fluid compositions (Polito et al, 2006).
Figure 02 (above): Tonnage-grade characteristics of Australian Unconformity Uranium Deposits.
Figure 03 (above): Outcropping geology superimposed on magnetics.
Geology
The Murphy project is located along the Murphy Tectonic Ridge, which is the southern mirror image of the Alligator Rivers Uranium Field (Fig 3, 4). It is in an area where the shallowly-dipping mid-Proterozoic unconformity that is associated with large deposits like Jabiluka and Ranger lies under thin sand cover.
Regional geophysical datasets show that the area has abundant faulting and dolerite dykes of a style similar to that which hosts mineralization further to the north (Fig 4).
The Murphy project is situated in the area where the early to mid Proterozoic rocks of the Murphy Tectonic ridge pass under shallow younger cover. The key mid-Proterozoic unconformity, equivalent to the Kombolgie unconformity in the Alligator Rivers Region, lies under the Westmoreland Conglomerate.
Figure 04 (above): Interpretation of subsurface geology in area of Murphy tenements.
Approximately 100 kilometres of this unconformity occurs within the Murphy Tenement package. The oldest rocks below the unconformity are the Murphy Metamorphics, a sequence of variablycarbonaceous metasediments and quartzite (Fig 5, 6). To the east of the area these are overlain by the felsic Cliffdale Volcanics. The Nicholson Granite is broadly coeval with the Cliffdale volcanics. The Westmoreland conglomerate lies immediately above the unconformity in the Murphy Project area. It is the stratigraphic equivalent of the Kombolgie Formation which overlies mineralisation in the Alligator Rivers Region.
Uranium mineralisation is recorded in numerous localities in the Murphy Inlier and vicinity (Fig 5). Uranium mineralisation has been recognised in the Murphy Inlier region in numerous structural and stratigraphic positions. These include:
- associated with faults and fractures in Murphy Metamorphics;
- in shear zones in the Cliffdale Volcanics near the Westmoreland Conglomerate unconformity;
- at the reverse-faulted contact between Cliffdale Volcanics and Westmoreland Conglomerate;
- within Westmoreland Conglomerate — about 50m above its base;
- in Westmoreland Conglomerate in close proximity to the overlying Seigal Volcanics;
- in association with mafic dykes and sills; and,
- in shear zones within the Seigal Volcanics.
Figure 05 (above): Schematic geology and target styles in the Murphy project area.
Figure 06 (above): Schematic diagram of the target geology and exploration approach for the Murphy area. Geological interpretation and track etch screening is used to define target areas, which are then subject to RAB drilling with the aim of detecting haloes of anomalous uranium and clay alteration. Phase 2 drilling is then used to test the entire Westmoreland-basement interval for mineralisation.
Overview of Exploration Results
During the 1970’s uranium exploration was undertaken in the region by a number of companies including Esso Australia, Noranda, Union Oil and Otter. Work included airborne radiometric surveys, ground follow up and rock chip sampling, and groundwater sampling from existing water bores. Limited percussion and diamond drilling of specific radiometric anomalies and shallow reconnaissance drilling along tracks was also undertaken. Four reconnaissance holes were drilled on and adjacent to the south western part of the current EL24694. No significant results were reported. The majority of exploration work undertaken in this period occurred to the east and north of the Buffalo tenement holding.
Since 2005, work on the properties has included a Hoistem airborne electromagnetics survey, a detailed interpretation and targeting exercise over the main prospective areas, a 100 metre-spaced airborne magnetic and radiometric survey, and a program of Radon track etch sampling of high priority target areas.
A target identification study carried out by Douglas Haynes Discovery Pty Ltd (Fig 7, Table 1) resulted in the identification of a number of high priority areas for unconformity-style uranium mineralisation of the East Alligator and Westmoreland type. The geological basis for the study was a new geological and structural interpretation of the thinly covered Mesoproterozoic and Paleoproterozoic sequences in the Murphy area. This interpretation was then used in order to identify favourable structural and stratigraphic sites for concealed uranium mineralization.
Figure 07 (above): Detailed geological interpretation and Uranium targets as selected by D. Haynes. See table one for discussion of targets.
The project area contains twelve high priority uranium target zones based on identification of favourable host rocks, fault intersections and alteration interpreted from published geological maps, open file historical exploration data, landsat imagery, and geophysical data (including aeromagnetics, radiometrics, HOISTEM and gravity).
Exploration on the Murphy project during 2007 included radon track etch sampling (Figs 7-11) of several of the high priority uranium targets and the completion of the airborne magnetic and radiometric survey by Fugro Airborne Surveys Pty Ltd. The Radon track etch cups, to detect radon gas from a buried uranium deposit, were placed over targets UC16, 18, 19 and 22 in the southern part of the tenements and UC6, 7, and 8 in the northern part of the tenements for a total of approximately 915 cups, and results were received late in the December quarter (8, 9, 10, 11). Results from additional infill and extension sampling are expected in the April-May period.
Figure 08 (above): Track etch sample sites overlain on merged colour Uranium Channel radiometrics and greyscale Vertical Derivative RTP Magnetics.
Figure 09 (above): Contours of track etch results overlain on Vertical Derivative RTP Magnetics.
Figure 10 (above): Murphy project southern area - contours of Track Etch results superimposed on a greyscale image of the First Vertical Derivative from the new high resolution airborne geophysical survey.
Figure 11 (above): Murphy project northern area - contours of Track Etch results superimposed on a greyscale image of the First Vertical Derivative from the new high resolution airborne geophysical survey.
Track Etch surveys in the southern part of the Murphy project area (Fig 10) have highlighted at least 9 discrete target zones where faults and favourable stratigraphy are associated with radon leakage which could potentially be related to a buried uranium orebody. One of the strongest of these lies at the northwest end of the UC19 target area, where a 2km-long track etch anomaly is coincident with a bend in a northwest trending structure and the trace of sandstones of the Westmoreland group.
Track Etch surveys in the northern part of the Murphy project area (Fig 10) have highlighted at least 8 discrete target zones where faults and favourable stratigraphy are associated with radon leakage which could potentially be related to a buried uranium orebody. A number of these targets occur in zones where Westmoreland Group Sandstones are interpreted to overlie Peters Creek Volcanics, where the track etch anomalies are coincident with northwest and north-northwest trending faults.
A heritage survey to determine any ‘sites of significance’ within the Murphy project was conducted over the area by the Aboriginal Areas Protection Authority (AAPA). All proposed areas of activity were successfully cleared for future exploration activity. The company also submitted in November an MMP (Mine Management Plan) application for permits to clear tracks and drill, and approval of this application was received in the first quarter of 2008.
Exploration Program 2008
Exploration at Murphy in 2008 has comprised scout drilling of the current targets as well as continued track etch sampling of other target areas (Fig 12). Widely spaced scout drilling is being carried out at a drillhole spacing appropriate for recognition of alteration haloes (Fig 13), which are relatively well understood for this style of mineralisation as well as being aerially extensive.
Figure 12 (above): Planned first stage RAB holes overlain on Vertical Derivative RTP Magnetics.
Figure 13 (above): Closeup of track etch contours and planned RAB holes for UC19 area showing schematic footprints of mineralisation and alteration at same scale.
Later phases of the program will follow up with closer-spaced drilling over areas of scout drilling where halo-style alteration and mineralisation has been previously intersected (Fig 6).
The first phase of drilling on the project comprised 138 RAB holes for 6428 metres, testing 10 different target areas which had been developed based on detailed magnetics and radiometrics, Hoistem airborne EM survey results, and Radon track etch anomalies. All the targets which were drilled are in the correct geological setting for unconformity uranium mineralisation of the type seen in the East Alligator region (eg Jabiluka - 360 million lbs at 0.45% U3O8) or of the type seen in the Westmoreland region (eg Westmoreland – 48 million lbs at 0.09% U3O8) in Queensland.
The targets all lie under a thin veneer of recent cover and were therefore never prospected in the last uranium boom, despite the fact that they display all the correct geological ingredients for this style of mineralisation.
Drilling was carried out on targets which were developed on the basis of interpretation of geophysical datasets under shallow cover. The original targets were followed up by Alphatrack (radon track etch) sampling which produced anomalous results interpreted to be related to potential underlying uranium
mineralisation. Radon track etch sampling has been previously shown to have successfully detected the Koongarra uranium deposit under 75 metres of cover.
Drilling targeted two main zones – the Westmoreland Conglomerate immediately under the Siegal Volcanics (Westmoreland Style) and the reduced Murphy Metamorphic basement immediately under the base of the Westmoreland Conglomerate (East Alligator Style) (Fig 5, 6).
Of the targets tested, the UC19 target produced the most encouraging results (Fig 14, 15). UC19 was originally identified as a high priority geological target and was then ugraded substantuially by returning the highest track etch survey results. Wireline logging of RAB drillholes in the UC19 area produced a number of anomalous equivalent-U3O8 intersections (Fig 14, Table 3).
Figure 14 (above): Murphy project, best-in-hole borehole logging results from the RAB drilling completed during the quarter.
Figure 15: Hychip logging results – illite crystallinity and illite composition, showing distictive alteration around UC19.
These are extremely anomalous values compared to the very low (less than 10ppm) background uranium concentration of the Westmoreland Sandstone. Anomalous values occur sporadically over a 10km strike length.
Drill chips from all drillholes were also analysed for clay mineral species using the Hychip infrared spectroscopy system. This work identified a distinctive illite signature associated with the UC19 target area (Fig 15). Such signatures are common in unconformity-related uranium deposits such as Jabiluka (NT), Cigar Lake and McArthur River (Saskatchewan, Canada).
RAB Drilling recommenced at Murphy in July, with a priority on further drilling at UC19 and drill-testing of other similar targets defined in an updated interpretation of the high resolution airborne geophysical survey flown in late 2007. The company is planning a followup RC drill program with an initial 2000m budget, and has preliminary commitment for a suitable RC rig in September.
Bondi Mining has spent approximately $A1.5 million dollars on the Murphy project in the July 2007 to June 2008 financial year. In that time, the project has advanced from a grass roots play with strong conceptual targets to a project with strong confirmation of the technical underpinning of the exploration play and validation of the exploration approach employed. Some of these key advances are as follows:
- Geophysics and drilling have confirmed the interpreted geological setting of the identified target areas
- Followup exploration has confirmed the detection ability of the track etch method – the strongest track etch anomaly encountered to date has been associated with the moste
- anomalous uranium as well as clay alteration characteristic of unconformity-style deposits
- One of the high priority targets identified has produced encouraging uranium anomalism and
- distinctive alteration, and merits deeper second pass drilling
The success of the project to date has led Bondi to formulate a new phase of exploration which will comprise broader track etch sampling of favourable structural and stratigraphic settings based on improved knowledge of the detailed geology of the area, deeper RC drilling of the UC19 target, and further scout drilling of anomalies obtained from additional track etch sampling.
For Further Information
Please contact:
Dr Rick Valenta P. Geo FAUSIMM
Managing Director
T +61 (0)7 3369 4000
F +61 (0)7 3369 4900
rvalenta@bondimining.com.au
Description of targets identified within the Murphy project:
| Name | Total Rank | Tech Rank | Comments |
UC Six |
287 | 70 | This is a target for uranium mineralization on the WC-Murphy Inlier “basement” contact, but occurrence of such basement here is difficult to confirm-it may be the PCV or a mafic volcanic unit underlying the WC instead of basement. Even if so, the target is of identical rank because of the very well defined alteration, high angle fault sets, culmination and the uranium radiometric anomaly. |
| UC Four | 239 | 63 | This is a target for uranium mineralization on the PCV-WC contact. There is locally exceptional indication of alteration in the main Emu Fault zone where it is intersected by WNW- and NEtrending altered faults or joint sets. Target is within a complex domal structure containing high-angle faults. Potential for a large body of mineralization could exist here, although proximal sources of reductant are difficult to define here. |
| UC Seventeen | 262 | 61 | This is a target for uranium mineralization on the WC-Murphy Inlier basement contact, and for uranium mineralization in basement below the unconformity, associated with N and W sets of dykes and high angle faults intersecting and offsetting the unconformity. This is a target for a more classical style of unconformity associated uranium mineralization, although the redox state of basement not certain. There may be thin APB above the WC here and resting on the Murphy Inlier “basement”, although mafic volcanic rocks beneath the WC may cause much of the signature indicating possible APB here. |
| UC Eighteen | 258 | 60 | This is a target for uranium mineralization on the WC-Murphy Inlier “basement” contact, and in basement below the unconformity, associated with NW set of dykes and high-angle faults intersecting and offsetting the contact. This is a more classical unconformity uranium target, although the redox state of basement is not certain. There is a possible nearby granite, with an associated mafic dyke sill complex or contact aureole, of pre-WC age. |
| UC Seven | 224 | 59 | This is a target for uranium mineralization on the WC-PCV contact, which bounds a downfaulted block of the PCV within in the WC. The down-faulted block is close to a regional-scale set of NW-trending faults, where they cross the Emu Fault zone. There is a strong indication of alteration and associated uranium radiometric response, noting that the radiometric signature is poorly sampled here. |
| UC Fifteen | 234 | 57 | This is a target for uranium mineralization on the WC-Murphy Inlier “basement” contact, at the S end of the Emu Fault Zone, with interpreted NW-trending sets of dykes and faults intersecting and offsetting the contact. The target has very strong empirical support as it contains EM anomalies and a moderate uranium radiometric anomaly, although the redox state of basement not certain. |
| UC Nine | 189 | 54 | This is a target for uranium mineralization on the WC-PCV contact within a fault-bound and uplifted block of WC. The block is defined by a N-trending fault set where this is intersected by a set of WNW-trending altered faults. There are very good alteration signatures and high amplitude uranium radiometric anomalies here. |
| UC Twenty Two | 217 | 53 | This is a target for uranium mineralization on the WC-Murphy Inlier “basement” contact. There are associated well-defined EM anomalies, which may indicate chlorite-illite alteration and uranium mineralization. Alternatively, these anomalies may be of interest for nickel copper. |
| UC Fourteen | 213 | 52 | This is a target for uranium mineralization on the WC-Murphy Inlier “basement” contact. NWtrending high-angle faults that likely contain dolerite dykes occur here. Note that the position of contact (unconformity) and the redox state of the basement is highly uncertain here. |
| UC Eight | 179 | 47 | This is a target for uranium mineralization on the WC-PCV contact, within a NW-trending fault where there is associated weak uranium radiometric anomaly response. However, indications of closure on contact are not strong, but interpretation is difficult in this area because of likely APB here. |
Description of planned exploration and preliminary outcomes on individual targets:
| Target | Style | Program | Results |
UC19 |
East Alligator | 45 RAB holes testing favourable structural locations with strong Alphatrack response, developed where the Westmoreland unconformity lies under thin sand cover. | Approx 41 holes for 2,070 m Anomalous scintillometer and gamma logs in 4 holes Westmoreland conglomerate unit intersected below Mesozoic sediments and Cambrian basalt (45 – 60m+) The sandstone was deeper on the south side of NW trending fault (North side up movement) Drilled approx 10 holes in the centre of the target where the alpha track cups were not retrieved, due to the fire. |
| UC6 | Westmoreland | 45 RAB holes testing favourable structural locations with strong Alphatrack response, including possible dyke-fault intersections similar to those developed at the Westmoreland deposit |
Drill holes MURB055 – 066 were drilled on target UC6. All the holes hit water, between 35 – 45 m depth at the base of the ‘Mesozoic’ cover sequence where the sandstone was intersected. Most holes were drilled to over 50m and were slow due to the high water flows. No holes in the central and western parts of UC 6 were drilled. |
| UC15 | East Alligator | 25 RAB holes testing structural targets in zones of favourable NNW-NW fault intersections with abundant mafic dyke development | Five holes MURB067 – 071 were drilled on target UC15. MURB 067 - 068 on line 8,040,800 N intersecting water at approx 22m in the sandstone and the holes finished at 34 and 46m respectively. MURB069 – 071 on line 8,043,200 N hit water at 36 – 55m and the holes finished at 52, 44 and 60m respectively. These holes generally hit fine sandstone – conglomerate with high water flows. Previous drilling on UC 15 had been very shallow (20 – 30m) as the holes were terminated when water was intersected. |
| UC8 | Westmoreland | 25 RAB holes testing an area with Alphatrack anomalies at the interpreted contact between the Siegal Volcanics and the underlying Westmoreland Sandstone (identical stratigraphic position to the Westmoreland deposit) | Not drilled |
| UC7 | Westmoreland | 25 RAB holes testing Alphatrack anomalies associated with variably-oriented structures located in close proximity to the contact between the Siegal Volcanics and the Westmoreland Sandstone | Not drilled |
| UC22 | East Alligator | 9 RAB holes testing northwest-trending Alphatrack anomalies associated with the interpreted contact between the Westmoreland Sandstone and the underlying Murphy metamorphics. | Holes MURB088 – 093 were drilled on UC22. All holes intersected variably weathered intermediate to mafic intrusive, which I would call dolerite (field description). In some holes this was fresh at 14m in others it was weathered to 50m. A NNE – SSW traverse to the west intersected relatively shallow, hard sandstone and a medium grained mafic dyke on the northern margin. Approx 5 holes were drilled on a SW – NE traverse across one of Douglas Haynes new targets. Most of the holes intersected fresh, hard, unaltered sandstone at relatively shallow depths. The northernmost hole intersected a medium grained mafic dyke, as suggested in the interpretation. |
| UC16 | East Alligator | 9 RAB holes testing zones of Alphatrack anomalism associated with an inferred paleohigh in the Murphy metamorphic basement | Intersected basalt and sandstone and quite high water flow. Difficult drilling conditions encountered. Thick basalt intersected in several holes |
| UC18 | East Alligator | 7 RAB holes testing zones of Alphatrack anomalism associated with northwesttrending structures in close proximity to the basement contact, intruded by northwesttrending mafic dykes. | Drilled MURB072 – 087 on UC18 including 3 holes on the conductor defined by J. Coggon to the NW. Water was intersected between 34 – 50m down hole. Most holes intersected sandstone and chert rich conglomerate (?). Several holes intersected very ferruginous (goethite / limonite) conglomerate and sandstone. The open cavities led to the abandonment of the holes. Holes on UC18 extended intersected deeper Mesozoic sediments to the south, as well as ferruginous conglomerate and cavities. |
| BM11 | U/Base metal | 5 RAB holes testing a NNW-trending dyke zone along the main strand of the Emu fault | Two holes drilled – one hole hit quartzite |
| BM7 | U/Base metal | 5 RAB holes testing the intersection zone between a north-trending mafic dyke and a northwest-trending conductor within Murphy Metamorphic basement | Not drilled |
Selected borehole wireline logging results:
| Hole-ID | From | To | Length (m) | eU308 (ppm) | max eU308 (ppm) |
MURB010 |
41.85 | 42.30 | 0.45 | 78 | 97 |
| MURB024 | 33.75 | 33.90 | 0.15 | 52 | 52 |
| MURB026 | 16.70 | 17.40 | 0.70 | 84 | 101 |
| MURB026 | 21.80 | 22.15 | 0.35 | 52 | 53 |
| MURB026 | 49.80 | 50.35 | 0.55 | 94 | 122 |
| MURB031 | 37.75 | 38.80 | 1.05 | 85 | 106 |
| MURB035 | 6.70 | 7.45 | 0.75 | 73 | 100 |
| MURB035 | 15.85 | 16.15 | 0.30 | 64 | 69 |
| MURB040 | 29.75 | 30.60 | 0.85 | 56 | 60 |
| MURB040 | 31.30 | 31.70 | 0.40 | 52 | 53 |
Results are taken from borehole logging by Borehole Wireline Pty Ltd of Adelaide.
