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Cape Preston, Sino Iron - George Palmer, Balmoral South, Balmoral North |
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Western Australia, WA, Australia |
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Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Cape Preston mine of the Sino Iron Project is developed on the George Palmer deposit. It is located 80 km to the SW of Karratha in the Pilbara region of Western Australia and around 30 km south of the Indian Ocean port site at Cape Preston (#Location: 21° 4' 27"S, 116° 8' 33"E).
George Palmer is flanked along strike to the south and north respectively by the Balmoral South (#Location: 21° 8' 27"S, 116° 7' 26"E) and Balmoral North (#Location: 21° 0' 47"S, 116° 9' 32"E) magnetite deposits,
Balmoral South, with a strike length of ~6 km, is the southern of the three adjacent, 15° trending sections of the Balmoral group of deposits east of the mouth of the Fortescue River. George Palmer is the central deposit, and has a strike length of ~6 km, immediately to the north of Balmoral South. The third, or northern 8 km long block, is Balmoral North, which is separated from George Palmer by a gap of ~2 km. The three deposits of the Balmoral group extend over a total strike interval of near 25 km. Development of these resources is intended to produce magnetite concentrate and pellets for export.
See the Hamersley Basin Iron Province record for the regional setting and stratigraphy.
The George Palmer and Balmoral deposits are developed within the Brockman Iron Formation of the Hamersley Group, on the north-western, generally north-south trending margin of the overall WNW-ESE elongated Hamersley Basin, in the Pilbara Craton. The Hamersley Group is part of the Neoarchaean to Palaeoproterozoic volcanic and sedimentary sequence of the Mount Bruce Supergroup which spans a time interval of over 400 m.y., from greater than 2.77 to near 2.35 Ga, and comprises the southern half of the Pilbara craton, passing below younger Palaeo- to Mesoproterozoic rocks to the south. It rests unconformably on 3.50 to 2.80 Ga granitoids and greenstones that occupy the northern half of the craton.
The Mount Bruce Supergroup is sub-divided into three Groups. The lowermost of these, the Fortescue Group, is conformably overlain by the 2500 m thick Hamersley Group, which is characterised by around 1000 m of laterally extensive banded iron formation representing three major episodes. The basal Marra Mamba (2600 Ma) and the medial >Brockman Iron Formations are separated by the carbonate, shale and minor chert of the Wittenoom, Mount Sylvia and Mount McRea Shale Formations (2600 to 2480 Ma). This passive Brockman sequence is followed by the third phase, the Weeli Wolli Iron Formation, which was accompanied by intense 2450 Ma bimodal volcanism and mafic sills (locally accounting for up to 80% of the sequence), overlain by the felsic volcanics of the Woongarra Formation and the uppermost ~450 m thick Boolgeeda Iron Formation. Thickness variations in the Hamersley Group are only minor.
The mineralisation at the Balmoral group of deposits, is hosted by the Brockman Iron Formation of the Hamersley Group, which also hosts many of the major hematite iron ores of the Pilbara. In the Balmoral deposits, the Brockman Iron Formation is composed of the following lithologies and thicknesses, from the base:
Dales Gorge Member, ~150 m thick - interbedded BIF and shale,
Whaleback Shale Member, ~60 m thick - interbedded shale, chert and BIF,
Joffre Member, ~300 m thick - BIF with minor shale bands,
Yandicoogina Shale Member, ~60 m thick - shale and BIF.
The George Palmer and Balmoral deposits are developed within both the Dales Gorge and Joffre Members, at the top of the Brockman Iron Formation. The Joffre Member is overlain by shales of the Yandicoogina Shale and underlain by the Whaleback Shale and Dales Gorge BIF Members of the Brockman Iron Formation.
The Joffre Member is dominated by BIF, with only minor, thin, centimetre scale shale interbands that are not as laterally persistant as those of the underlying Dales Gorge Member. The BIF units are principally magnetite and chert bands with lesser hematite and martite. Locally, the Joffre Member has been divided into around six 20 to 100 m thick units, comprising either BIF alone or BIF with shale bands.
The un-modified Joffre Member usually has a stratigraphic thickness of approximately 360 m. However, in the Balmoral area, the average interpreted thickness is around 300 m, suggesting deflation through leaching and removal of components of the original unit. The BIF strikes between 15 and 20° and dips consistently at near 45° WNW. Faulting plays an important part in the geology of the deposits, with near strike-slip structures in places juxtaposing the BIF against itself, resulting in repetition of stratigraphy, increasing the effective mining width and reducing waste. However, the same faulting has truncated the Joffre Member at depths of 300 to 400 m below the surface, whilst the Dales Gorge Member, which is lower in the sequence persists to slightly greater depths. The principal fault directions are NNW-SSE and NE-SW, dipping moderately to the east or SE. Large scale folding has not been observed, although soft sediment slumping of the denser iron oxide bands into the chert and shale bands is evident.
Thin, NNE- and NE-trending post-orogenic dolerite dykes are common, parallel to the dominant faulting, principally in the more competent rocks (cherts), although sills have not been observed. These dykes are only minor and are not a dilutant, with thicknesses of <5 m, but occasionally up to 30 m.
The ore at George Palmer is a laminated, metamorphosed oxide-facies iron formation in which the original chert or jasper bands have been recrystallised into distinguishable grains of quartz and the iron is present as thin layers of hematite, magnetite or martite. The reserves and resources quoted below show the magnetite content and total iron which includes both the magnetite and associated hematite.
Total proved + probable reserve at George Palmer, 2005 (Golder Assoc. in Citic Pacific 2006 circular):
793.8 Mt @ 22.6% Fe mag, 31.3% Fe total.
Total measured + indicated + inferred resource at George Palmer, 2005 (Golder Assoc. in Citic Pacific 2006 circular):
2.185 Gt @ 22.1% Magnetite, 31.3% Fe total.
Probable ore reserves at Balmoral South in March 2009 on a cut-off grade of 15% MagFe (Australasian Resources website, 2013):
859 Mt @ 22.6% Fe mag, 31.2% Fe total,
which can be upgraded to 260 Mt @ 69.0% Fe, 3.9% SiO2, 0.1% Al2O3, 0.02% P2O5,
Total indicated + inferred resources at Balmoral South in 2006 (Australasian Resources website, 2009):
1.605 Gt @ 22.6% Fe mag, 31.2% Fe total,
which can be upgraded to a concentrate (80% passing 32µm) of 69.0% Fe, 3.9% SiO2, 0.1% Al2O3, 0.03% P2O5,
Total indicated + inferred resources at Balmoral North in 2009 (Hellman & Schoefield, Independant Geologists Report, 2009):
920 Mt @ 21.0% Fe mag, 31.1% Fe total,
Note: Fe mag = percentage of magnetically recoverable Fe in ore
It is estimated for the George Palmer ore that the conversion ratio of magnetite ore to concentrate/pellet is 3.4 to 1 for this project (Citic Pacific, 2006).
The most recent source geological information used to prepare this decription was dated: 2009.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
George Palmer Balmoral South Balmoral North
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Selected References:
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Hellman and Schofield Pty Ltd 2011 - Appendix IV-B, Independent geologists reports - iron ore: in Resourcehouse Limited Prospectus Global Offering Hong Kong Exchanges and Clearing Limited website, psh.hkex.com.hk/userpages/eipo/english/ Resourcehouse(new)_e.pdf pp. IV-B 1 and IV-B 10-39
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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