Aditya Birla Minerals is primarily focused on copper production and holds copper exploration tenements around the existing Nifty, Mt Gordon and Maroochydore Copper Projects. Focusing on resource building for underground mining for its Queensland and Western Australian copper mines, the company is continuing to undertake near mine and regional exploration drilling programmes throughout FY 2014. A total of 36,904m of near mine and regional diamond and reverse circulation drilling was completed during the year over these project areas.
Since inception in 2003, Aditya Birla Minerals has concentrated on mine development and resource and reserve delineation drilling within and adjacent to current projects. The company has significantly increased its exploration activities at both sites, particularly at the Mt Gordon copper project in Queensland, Australia, where the discovery of new high grade copper sulphide mineralisation at Mammoth has contributed to a significant increase in resources and the potential scale of the project and copper output. In addition to copper exploration in Australia, Aditya Birla Minerals has continued to pursue international exploration and development opportunities.
Advanced Queensland and Western Australian Exploration
Aditya Birla Minerals has expanded its tenement holding to some 6,400 sq. km of copper exploration tenements around the Birla Nifty Copper Operation (BNCO) in the Great Sandy Desert, WA and holds approximately 1,800 sq.km in the Mt Gordon Copper project located in the Mt Isa Block, QLD. In addition to these copper exploration tenements, the company holds exploration and mining rights to the Maroochydore Copper Project, located only 100km from the Nifty mine site. Exploration targets are generated using the integration of data from a comprehensive geological, geophysical, geochemical database using stratigraphic and structural interpretation with specialist input in critical fields.
The Nifty Copper Operation lies approximately 350km southeast of the Port Hedland loading facility at the western margin of the Great Sandy Desert.
Birla Nifty Copper Project – Exploration
Surface and Underground Resource Delineation Drilling
A total of 11,000 metres is planned from surface and underground resource delineation drilling. A 5,000 metre programme of surface drilling was commenced in March 2014 but the drilling programme put on hold due to the sinkhole development. A 6,000 metre underground resource conversion drilling programme planned from 20th level was also put on hold due to the sinkhole development. Both programmes are designed to convert Inferred resources into Indicated and Measured resources.
Leach Pad Drilling
A 1900m RC drilling programme on 50 x 50m hole spacing was recently completed upon the Nifty heap leach pad for the purposes of bulk metallurgical sampling and to provide the basis for in-situ resource estimation.
Near Mine Exploration Drilling
A 13,654m programme of surface and underground drilling was conducted during FY14, completing testing the DHEM targets northwest of the pit, the DMP co-funded drill hole 2km west of the pit and a number of down plunge targets over a strike length of 1.5Km.
Drilling NW of the pit encountered sub-economic quantities of copper mineralisation in a footwall shale horizon which requires follow-up down plunge to test the possibility for improved grades and thickness in footwall shales at depth below the Nifty copper deposit.
Drilling of the central synclinal trough located no further significant mineralisation down plunge of previously reported drill holes YNC341B and YNC342 over the 1.5Km strike length tested. Further structural modelling will be undertaken before further down plunge drilling is undertaken.
Drilling of the co-funded hole YNC350, approximately 2Km southwest of Nifty located minor copper mineralisation at relatively shallow depth adequately testing this area. The second planned co-funded hole testing the same concept has been re-located to test a new location 1km northeast of the mine site. One 600m hole, illustrated in the underlying figure, has been planned to test the zone of low conductivity shown as potentially representing an alteration halo to copper mineralisation, given its similarity to the low-conductivity signature of the alteration envelope and host rocks of the Nifty copper deposit. Prior drilling, collared approximately 1 km along strike to the northwest of the planned hole, intersected 4.08m @ 1.51% Cu from 328.9m depth in YNC304.
Finch Copper Prospect
This prospect lies in the Nifty syncline approximately 14km south of Nifty. Interpretations of regional electromagnetic, magnetic and gravity geophysical data extending from Finch to Nifty were completed and provide a good correlation with the Nifty stratigraphic sequence. Copper sulphide mineralisation at Finch has been intersected during limited previous drilling in the Nifty syncline and is spatially associated with a local plunge reversal, splay faulting, a major NE-trending cross-fault and lateral dispersion of secondary copper mineralisation along and across strike. The central trough and northern limb warrant drilling to test for potentially significant copper mineralisation at depth as shown in the figures below.
Nifty Regional Exploration
Filtering, imaging and interpretation of the high resolution aeromagnetic survey data acquired in FY13 over the Nifty and Maroochydore areas and re-interpretation of regional high quality VTEM data over the Nifty mine and regional areas were completed. Prospect-specific desktop analysis of all updated geophysical, geological and geochemical data from the Nifty near mine, Nifty Regional and Maroochydore areas was then used to derive a series of targets for drilling.
A total of 2,852 metres of reverse circulation and pre-collared diamond drilling was completed on regional Nifty targets at Rainbow, Mansfield and Citadel. Drilling outcomes were best at Rainbow. Three RC holes each intersected shallow weak to moderate stratabound copper mineralisation near the interface of the Broadhurst Formation and Coolbro Sandstone at the flanks of an anticlinal structure adjacent to the major Vines Fault.
A follow-up programme of RC drilling at Rainbow and Rainbow South is planned over two areas 1 km southeast along the same structural trend testing the flanks of similar structures at shallow depths with a provision for step out drilling on 400m spacing as shown in the figure below.
This plan illustrates the potential for this horizon to be regionally present near surface and at depth over an area of approximately 10km x 25km due to repetition of the host stratigraphy by folding and faulting. The conductive formations represent synclinal tracts of Broadhurst Formation in which prior exploration has been focussed. Copper anomalism is present in many historic holes distributed over this area where reconnaissance drilling has often not tested these areas to depth. Broad areas of copper anomalism (>150ppmCu) occur over areas highlighted in pink. Moderate to strong levels of copper anomalism (250 to >1000ppm) clustered around a major fault junction near the Grevillea-Stirling prospects are under review for drilling.
Birla Maroochydore Copper Project
The Maroochydore Copper Project lies approximately 100km south-east of the Nifty copper mine.
3D Modelling of the Maroochydore primary sulphide resource was completed and a maiden resource released to ASX. This is the first primary copper sulphide resource discovered in the Great Sandy Desert since the discovery of Nifty. It remains open along strike and down dip and contains approximately 90,000t of in-situ copper.
Maroochydore Copper Resources
The Maroochydore Oxide, Supergene and Sulphide Mineral Resources at 31 March 2014 now stand as shown below.
Copper Resources-Oxide and Supergene Mineralisation
|Cut-off||Category||Tonnes||Copper (%)||Co ppm|
|Cut-off||Category||Tonnes||Copper (%)||Co ppm|
The 2013 drilling programme totalled 5,532m of pre-collared RC/DD drilling and predominantly tested a broad area of the eastern Maroochydore tenement areas to depths of 300 to 800m. Drilling tested blind large scale structures based upon specialist interpretation of detailed magnetic and gravity data. All holes intersected Broadhurst Formation sediments, gabbro intrusive and the target zone at the predicted depth. Most holes intersected moderate to strong pyrrhotite but were deficient in chalcopyrite. Weak chalcopyrite was intersected in drill holes 13MAD007 and 13MAD010, extending the north-westerly strike of the Maroochydore copper sulphide mineralisation by a further kilometre and to a vertical depth of 600m down plunge with a best copper intersection of 5m @ 0.35% Cu from 614m at a 0.3% Cu cut-off ( 13MAD010).
Magnetic highs west of the deposit are interpreted as possible repetitions of a magnetic pyrrhotite horizon identified within a number of previous holes in the immediate footwall to the Copper Horizon.
The plan above shows all diamond and reverse circulation drilling undertaken since 2011 on the Maroochydore tenement that has targeted primary sulphide mineralisation.
Detailed magnetic modelling indicates the presence of a synclinal structure lying to the west of the Maroochydore copper deposit. Drill holes 13MAD008 and 13MAD009 located structural complications at the western boundary of the Maroochydore oxide deposit, suggesting possible down-folding or down-faulting to the west. It is planned to test targets to the west and south of the Maroochydore deposit for possible repetitions or extensions of the mineralised horizon within the newly recognised Maroochydore structural corridor and adjacent to and along strike of the oxide deposit.
Birla Mt Gordon Copper Project – Exploration
The Mt Gordon Copper Project is located in Northwest Queensland, approximately 120 km northeast of Mt Isa.
Spectacular copper mineralisation was intersected in hole SD532, testing the ore potential between the Esperanza/Pluto and Mammoth Resources. High grade mineralisation was intersected at a depth of 4265m RL located approximately 340m below the base of the Esperanza/Pluto Resource and 535m below the lower level of Mammoth North Resource.
Copper mineralisation was intersected from a depth of 808 to1038m providing a total envelope of 230m @ 1.02% Cu, 2.12g/t Ag, 385ppm Co.
High grade intersections include 54m @ 3.62% Cu, 4.62g/t Ag, 1,545ppm Co from 984m, including 19m @ 8.19% Cu, 7.26g/t Ag, 4,107ppm Co from 992m. Mineralisation remains open at depth and up and down dip.
A DHTEM (Down Hole Time Domain Electromagnetic) survey conducted down SD532 identified a significant conductor from ~ 840m to ~1030m down hole. Modelling indicates the conductor has at least 250m to 300m of lateral extent. Two wedge holes are planned to test along strike and up and down dip for extensions of this mineralisation.
A follow-up underground drilling programme was completed at Mammoth North that targeted a potential down dip extension of the Mammoth North deposit. Two holes were completed for a total of 966.90m. Assay results of these drill holes indicate that the Mammoth North deposit is merging with the Mammoth deposit at 4600rl.
Mammoth South is a new discovery. Two holes were planned to test the Mammoth South target testing the ore potential between the Micks and Portal faults. Copper mineralisation was intersected in both holes UM1572 and UM1573. Hole UM1572 intersected 7m @ 0.81% Cu from 213m incl: 4m @ 1.20% Cu from 216m and 9m @ 0.89% Cu from 226m incl: 2m @ 2.35% Cu from 236m. Hole UM1573 intersected 3m @ 1.74% Cu from 165m. Further drilling is required to define the ore potential at Mammoth South.
Mammoth Fault Convergence (MFC)
Two holes, UM1574 and UM1575, were planned to test the Mammoth Fault Convergence System from Mammoth underground. Drill hole UM1575 intersected 13m @ 0.54%Cu from 190m and 21m @ 1.26%Cu from 386m (incl. 4.0m @ 5.28% Cu from 403m) before being abandoned at 493m. UM1574 intersected 11m @ 0.93% Cu from 182m, incl 2m @ 2.54% Cu from 190m.
At Esperanza South the drilling program located the interpreted down dip extension of copper mineralisation that occurs along the regionally significant Esperanza Fault. Drill hole SD530W2 intersected mineralisation approximately 200m below the base of currently known mineralisation as shown in the figure below but deviated badly and further drill testing is required at this depth.
The information in this release that relates to Mineral Resources for the Maroochydore projects is based on and accurately reflects reports prepared by DataGeo and Sivasamy in 2013/14. Mr Ball and Mr Sivasamy have the necessary experience relevant to the style of mineralisation, the type of deposit and the activity undertaken to qualify as a ´Competent Person´ under the JORC Code for Reporting of Mineral Resources and Ore Reserves (2012 Edition). Mr Ball and Mr Sivasamy have given their consent to the inclusion of the material in the form and context in which it appears. Mr Ball is Principal of DataGeo Geological Consultant (an independent geological consultancy). Mr Sivasamy is a full time employee of Aditya Birla Minerals Limited.
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