Mining Area C

Western Australia, WA, Australia

Main commodities: Fe
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The Mining Area C iron deposits are located ~130 km ESE of Mount Tom Price, 90 km NW of Mount Whaleback and 30 km NE of West Angeles in the Pilbara craton of western Australia (#Location: 22° 55' 29"N, 118° 58' 28"E).

See the Hamersley Basin Iron Province record for the regional setting and stratigraphy.

Both Marra Mamba and Brockman martite-goethite iron mineralisation occurs within the area. Most of the Area C Marra Mamba deposits (A to F) are distributed over a strike length of near 25 km on the northern limb of the Weeli Wolli anticline, a broad, upright fold with an east-west trending axis. The Hope Downs deposit (see the Hope Downs record) is located on the same limb, 5 km to the east of the eastern extremity of Mining Area C. Further Marra Mamba ore accumulations are developed on the southern limb. Brockman deposits are developed parallel to the Marra Mamba accumulations. 2 to 3 km to the north on the northern limb of the anticline.

This fold and related structures were formed during the two major north-south compressional tectonic events recognised in the Hamersley Basin rocks on the southern margin of the Pilbara craton. The first of these, the ~2.45 to 2.2 Ga Ophthalmian Orogeny produced an arcuate fold and thrust belt, characterised by associated south-dipping thrust faults and north-verging asymmetric to overturned folds. The subsequent ~1.80 to 1.65 Ga Ashburton Orogeny, produced broader, more open and upright folds, such as the Weeli Wolli anticline.

Mining Area C is located on the northern and southern rims of an east-west elongated 30 x 8 km inlier of Marra Mamba Iron Formation that occupies the core of the doubly plunging Weeli Wolli anticline. It is overlain by the Wittenoom Formation and associated units of the Hamersley Group, succeeded to both the north and by the Brockman Iron Formation in the cores of parallel synclines.

The two orogenic events have also produced deposit-scale thrust faults and overturned folds, which are significant controls on the distribution of higher-grade mineralisation. In a study of the C Deposit Marra Mamba ore, which occupies a 4 km length of the northern limb of the Weeli Wolli anticline, Hagemann et al. (2007) noted that the structural controls on ore included: i). south-dipping thrust faults that developed along the contact between the Mount Newman Member of the Marra Mamba Iron Formation and the West Angelas Member shale of the Wittenoom Formation; ii). folds associated with thrust fault development; iii). steeply dipping stratigraphic contacts in the hanging wall and footwall of thrust faults; and iv). gently north-dipping stratigraphic contacts. They noted that thrust fault and folds are significant for two main reasons (e.g., Hodkiewicz et al., 2005): i). their formation produced a thickening of the main ore-hosting units in the Mount Newman member; and ii). the associated structures and folded lithological contacts acted as conduits for fluids that influenced the upgrading of iron formations to produce ore.

The resources in 2001 were stated at:
    C Deposit - 260 Mt at a grade of 62.1% Fe, 2.86% Silica, 1.76% Alumina, 0.065% P, 5.92% LOI,
    Additional Marra Mamba ore on the Northern Flank area total 580 Mt.

Resources and reserves at Mining Area C at 30 June 2012 (BHP Billiton, 2012) were:
    Measured + indicated + inferred Brockman resources - 2.274 Gt @ 59.5% Fe, 0.13% P, 5.7% SiO2, 2.7% Al2O3, 5.9% LOI;
    Measured + indicated + inferred Mara Mamba resources - 3.294 Gt @ 60.0% Fe, 0.06% P, 4.5% SiO
2, 2.1% Al2O3, 7.0% LOI;
    Proved + probable Brockman reserves - 381 Mt @ 62.2% Fe, 0.13% P, 3.4% SiO
2, 2.0% Al2O3, 5.2% LOI;
    Proved + probable Mara Mamba reserves - 362 Mt @ 62.1% Fe, 0.06% P, 3.4% SiO
2, 1.7% Al2O3, 5.7% LOI.

The most recent source geological information used to prepare this summary was dated: 2007.     Record last updated: 22/5/2013
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.

  References & Additional Information
 References to this deposit in the PGC Literature Collection:
Harmsworth R A, Kneeshaw M, Morris R C, Robinson C J, Shrivastava P K  1990 - BIF Derived Iron Ores of the Hamersley Province: in Hughes FE (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne   v1 pp 617-642
Thorne W, Hagemann S, Webb, A and Clout, J,  2008 - Banded iron formation-related iron ore deposits of the Hamersley Province, Western Australia: in Hagemann S, Rosiere C, Gutzmer J and Beukes N J, (eds.), 2008 Banded Iron Formation-Related High-Grade Iron Ore Reviews in Economic Geology   v.15 pp. 197221

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