BRAMFIELD IRON PROJECT
The Bramfield Project is located 9 km from Elliston on Eyre Peninsula, approximately 170 km from Port Lincoln (via a sealed highway).
Geology and Mineralisation
A large magnetic anomaly measuring ~2700 m in length and ~500 m in width was initially considered to represent a mafic-ultramafic intrusive complex but it has been shown to be more diverse than this with BIFs and calc silicate horizons.
Figure 4. The Bramfield Prospect – aeromagnetic image and drill sites
Previous investigations and results
The previous nearest drilling was carried out by Stockdale 10 km to the south-east of the magnetic anomaly where a kimberlite was intersected.
The iron formation was discovered in 2006 by Drill hole BLDD06, which intersected an east dipping (60-80º) sequence: iron-rich skarn and associated forsterite-magnetite marbles and calc-silicates.
The hole commenced in weathered iron formation which gives way down hole to magnetite-hematite rock.
The zone from 87.3 m to 125.1m assayed 37.8 m @ 40.40% iron. Oakdale drilled six diamond drill holes into a section of the the structure and the intersections include:
BLDD09 1.90 m grading 34.94% Fe from 186.30 – 188.20 m BLDD10 22.4 4m grading 34.15% Fe from 178.60 – 201.04 m 7.70 m grading 32.71% Fe from 252.40 – 260.10 m 1.10 m grading 38.25% Fe from 268.70 – 269.80 m 1.00 m grading 37.57%
Fe from 273.90 – 274.90 m 62.51 m grading 32.99% Fe from 282.82 – 345.33 m 3.32 m grading 31.81% Fe from 355.18 – 358.50 m BLDD20 36.20 m grading 42.39% Fe from 75.00 – 111.20 m BLDD21 53.00 m grading 39.77%
Fe from 82.00 – 135.00 m BLDD22 29.45 m grading 36.92% Fe from 152.65 – 182.10 m 3.95 m grading 35.04% Fe from 187.30 – 191.25 m
Silica, sulphur, alumina and phosphorus in the concentrate are acceptably low.
This drilling explores only a limited area of the magnetic anomaly, Figure 5.
Figure 5. Bramfield drilling pattern
The traverse of drill holes has revealed the complexity and folding in the strata with repetition of magnetite horizons, Figure 6.
Figure 6. Bramfield drill traverse - geology and intersections, geophysical magnetic traverse and interpretation
Magnetic surveys are one of the most reliable of geophysical methods and on the traverse presented on Figure 6 there is a clear interpreted second strong magnetic feature to the east of that which has been drilled. This feature is expected to be caused by more magnetic rich strata.
At AMDEL Limited, Mineral Services Laboratory (Amdel) in Adelaide, South Australia, Initial DAVIS TUBE Recovery (DTR) tests on the Bramfield drill core were carried out. Summary of the results below demonstrate that the Bramfield deposit produces a high grade (+68% Fe) concentrate with no damaging deleterious impurities present.
Conclusions and Future work
Oakdale has outlined by geophysics and drilling a substantial zone of BIF at the Bramfield Iron Prospect. This contains magnetite and hematite below the weathered zone with iron grades ranging from 31.8% to 42.4%.
Although a resource cannot be estimated at this stage, Oakdale has an aspirational exploration target of between 250 million tonnes and 300 million tonnes based on the extent of magnetic anomalism.
Drilling to estimate resources is the next step to define the potential over the full strike extent.
Overburden to the iron mineralization relatively soft sandy material and about 50 m thick, so open pitting would appear to be a suitable mining method.
The Bramfield Project is situated within an emerging iron ore province.
The surrounding region of the Eyre Peninsula on three sides of the Bramfield tenement is being investigated by listed iron ore companies for magnetite-rich mineralisation: Iron Road Limited (ASX Code: “IRD”),(~37 billion tonnes, see below), Lincoln Minerals (99.3 million tonnes grading 24.4% iron), IMX Resources NL (14.3 million tonnes grading 50.6% iron plus copper credits), South Australian Iron Ore Group (extensive exploration in five ELs) and Centrex Metals Limited (“Centrex”) in several joint ventures, (Inferred 368.4 million tonnes grading 25.2% iron, Indicated24.9 million tonnes grading 24.9% iron and Measured 10.8 million tonnes grading 22.7% iron.
Combined resources are ~680 million tonnes grading 25.1% iron). Further exploration will commence once the graphite has been evaluated and the iron ore market improves.