|
Weld Range - Madoonga, Iron Ridge, Beebyn |
|
|
Western Australia, WA, Australia |
| Main commodities:
Fe
|
|
 |
|
|
 |
Super Porphyry Cu and Au
|
IOCG Deposits - 70 papers
|
All papers now Open Access.
Available as Full Text for direct download or on request. |
|
|
The Weld Range iron deposits are located in the 2.7 to 2.6 Ga Gyr greenstone belt of the Murchison Terrane in the Yilgarn Craton, some 65 km SW of Meekatharra, 50 km NW of Cue and 360 km NE of the Indian Ocean port of Geraldton in Western Australia.
The Weld Range is a marked physiographic feature, comprising a series of parallel ridges that rise up to 250 m above the surrounding plains, separated by deeply incised valleys. The range extends over a length of nearly 60 km and has a width of 3 to 5 km.
In the Weld Range, the Gyr greenstone belt is predominantly composed of metabasites showing mainly doleritic and minor basaltic and gabbroic textures. Exposures of these lithologies occur between the ridges which are defined by weathered, steeply dipping beds of resistant banded iron formation (BIF) which form less than 10% of the thickness of the sequence. Poorly exposed, very fine grained clastic metasediments are only a very minor part of the sequence. Metamorphism is relatively low grade, varying from lowermost greenschist facies in the north to approximately greenschist-amphibolite transition facies in the south.
High grade iron mineralisation in the Weld Range area occurs as a series of outcrops of massive goethite-haematite lodes.
A representative drill hole below a prominent ridge of one such highly weathered banded iron-formation intersected two beds of BIF, an upper 8 m thick and lower 105 m width, within a sequence of very fine-grained quartz-chlorite-rich metasediments. Most of the BIF was reported to show some evidence of secondary oxidation due to weathering, while even in the deepest parts of the hole, sections of the BIF were found to be altered. In the least weathered sections of core, the BIF has well preserved, arrested reaction textures showing a texturally early mineral assemblage overprinted by several generations of later minerals. The mineral assemblage recorded in the BIF, in a general decreasing order of abundance, are minnesotaite, siderite, quartz, magnetite, greenalite, stilpnomelane, pyrite and chamosite. Trace amounts of pyrrhotite, arsenopyrite, chalcopyrite and apatite are widely distributed, and rockbridgeite occurs in trace amounts in two samples. The proportions of the various minerals vary widely and over large sections of the core some of the minerals listed are absent. Much of the BIF is meso-banded, and very different mineral assemblages commonly occur in adjacent meso-bands (Gole, 1980).
Bands of 2 to 30 cm thick massive to laminated Fe-rich shales occur within the BIF, with both mineralogically sharp and gradational contacts with the enclosing BIF. The mineralogy of these shales, in approximate decreasing order of abundance, are chamosite, stilpnomelane, siderite, greenalite, pyrite, magnetite, minnesotaite and quartz. Trace amounts of ilmenite, chalcopyrite, and apatite are also present (Gole, 1980).
The earliest recognisable mineral assemblage contains AI-bearing greenalite, quartz, siderite, chamosite, magnetite, pyrite and rarely pyrrhotite. This assemblage is overprinted by stilpnomelane, sometimes accompanied by a secondary AI- and Mg-poor greenalite. Minnesotaite was developed after stilpnomelane from the reaction of earlier silicates and siderite. The suite of minnesotaite-quartz ±magnetite ±pyrite represents the complete reaction of the earlier assemblages. The observations in this and the previous two paragraphs are quoted from Gole, (1980).
Iron mineralisation in the Weld Range had first been recognised in the late 19th century, while modern exploration commenced in 1959 followed by drilling programs between 1970 and 1981, together with the development of two exploration adits.
Total mineral resources in two main deposits, Beebyn and Madoonga, 22 km to the SW (SRK Consulting, for Sinosteel-Midwest, 2008), was:
Beebyn - 61.2 Mt @ 60.9% Fe, 1.9% Al2O3, 4.9% SiO2, 0.10% P, 5.2% LOI.
Madoonga - 94.4 Mt @ 56.1% Fe, 2.0% Al2O3, 8.4% SiO2, 0.08% P, 8.1% LOI.
TOTAL - 155.5 Mt @ 58.0% Fe, 2.0% Al2O3, 7.0% SiO2, 0.09% P, 7.0% LOI.
The Sinosteel website, as viewed in July 2024 claimed the high grade resource in the Welf Range totalled ~300 Mt of ore, and that the resources at the Beebyn and Madoonga ore bodies are sufficient to support over 25 years of production.
Exploitation would require the construction of a 360 km rail link to the proposed deepwater port at Oakajee north of Geraldton in cooperation with other projects in the same region.
UPDATE
In October 2023, Fenix Resources Limited signed a binding agreement with Sinosteel Midwest Corporation to secure the exclusive right to mine and export up to 10 Mt (dry) of iron ore from the high-grade Beebyn-W11 iron ore deposit. Beebyn-W11 has a JORC 2012 Mineral Resource Estimate of 20.5 Mt @ 61.3% Fe, and is located is located only 20 km NE of the Fenix mining operations at Iron Ridge.
Unlike the more complex ores at Madoonga, the Beebyn deposit, which is located along the southern margin of the greenstone belt, hosts only one principle ore type, a hypogene 'residual' magnetite-rich ore that is interpreted to have formed by the replacement of primary silica-rich bands in BIF by hypogene carbonate gangue minerals, followed by their dissolution and concentration of primary magnetite-rich bands (Duuring and Hagemann 2012).
The Iron Ridge deposit is located between Madoonga to the NW and Beebyn to the NE comprises one main BIF horizon with significant iron enrichment in two locations (Wilgie Mia and Little Wilgie Mia). The mineralisation is composed of a mixture of banded hematite (specular and earthy), goethite and shaly limonite. The primary ore mineral is martite. The ore lenses have been formed by remobilisation of iron and replacement of jaspilites (BIF) during deep-seated thermal metamorphism. Subsequent supergene oxidation, leaching and hydration of the iron ore has resulted in the formation of goethite and the concentration of secondary hematite, occasionally occurring as red ochre (https://miningdataonline.com/ viewed July 2024). Three parallel to sub-parallel ridges of BIF have been mapped within the mining title. The Main hemaite BIF is ~50 m wide, whilst much thinner BIF ridge only a few metres thick occur to the south, known as Little BIF 1 and 2 respectively. These thin BIFs are defined by discontinuous goethitic outcrops at a lower elevation than the Main BIF (https://miningdataonline.com/ viewed July 2024).
The Iron Ridge deposit itself, within the Main BIF band, comprises two major, parallel BIF units, separated by 14 to 36 m. These BIFs outcrop over ~75% of the drilled strike length of 600 m. There is a sharp contact between the BIF and dolerite enveloping the 31 m of BIF 1 and 6 m of BIF 2. These thicknesses are consistent with depth, with B1 having been tested for 280 m of vertical extent in both the NE and SW. The depth of the north- eastern extent of BIF 2 persists for 176 m vertical depth, while the south-western extent reaches a 44 m vertical depth (https://miningdataonline.com/ viewed July 2024).
Pre-mining Mineral Resources at Iron Ridge (Fenix Resources ASX Release 21 Sept. 2020) quoted Indicated + Inferred Mineral Resources of direct shipping ore at Iron Ridge (inclusive of Ore Reservess) of:
10.5 Mt @ 64.2% Fe, 2.57% Al2O3, 1.96% LOI, 0.046% P, 3.26% SiO2, 0.09% TiO2. Of this only 0.5 Mt were Inferred Resources.
The included Probable Ore Reserves were - 7.76 Mt @ 63.9% Fe, 2.79% Al2O3, 2.00% LOI, 0.05% P, 3.46% SiO2, 0.09% TiO2.
In October 2020, Fenix Resources executed binding offtake terms with Sinosteel International Holding Company Limited for 50% of the proceeds of crushing, screening and trucking 1.25 Mt of ore per annum for export through the port of Geraldton.
The Madoonga deposit is hosted by a tectonostratigraphic sequence that includes, from north to south: i). a quartz-plagioclase- phyric volcanic and volcaniclastic rock intruded by dolerite and gabbro; ii). a <60 m thick northern BIF; iii). a <40 m thick volcaniclastic or (volcanogenic)-sedimentary rock; iv). a <150 m thick southern BIF; v). a 100 m thick pyritic mudstone, and; vi). dolerite interlayered with gabbro. These major rock types strike ENE and dip at >80° SSE. All primary contacts are deformed and transposed towards the main ENE-trending fabric.
Whilst Beebyn and Iron Ridge are on the southern margin of the Weld Range greenstones, Madoonga comprises BIFs on the northern margin. Unlike the Beebyn deposit, which is composed of only one principle ore type (as described above), Madoonga contains four spatially coincident, but genetically and compositionally distinct types of high-grade (i.e., >55 wt.% Fe) iron ore that includes:
• Hypogene magnetite-talc veins, that are up to 3 m thick and 50 m long formed within mylonite and shear zones located along the limbs of isoclinal, recumbent F1 folds. Relative to least-altered BIF, the magnetite-talc veins are enriched in Fe2O3, P2O5, MgO, Sc, Ga, Al2O3, Cl, and Zr; and depleted in SiO2 and MnO2. Primary igneous amphibole and plagioclase, as well as metamorphic chlorite of the mafic igneous countryrocks within 10 m of the northern contact of the mineralised BIF are replaced by hypogene ferroan chlorite, talc and magnetite. Later hypogene specular hematite- quartz veins and their associated alteration halos partly replace magnetite-talc veins in BIF and formed during, to shortly after, the F2-folding and tilting of the Weld Range tectono-stratigraphy.
• Hypogene specular hematite-quartz veins and their associated alteration halos partly replace magnetite-talc veins in BIF and formed during, to shortly after, the F2-folding and tilting of the Weld Range tectono-stratigraphy.
• Supergene goethite-hematite, forms ore zones that are up to 150 m wide, 400 m long, and extend to depths of 300 m, replacing the least-altered BIF and existing hypogene alteration zones. These zones formed as a result of the circulation of surface oxidised fluids through late NNW- to NNE-trending, subvertical brittle faults; and
• Supergene-modified, goethite-hematite-rich detrital ores, which occur as flat lying, detrital sedimentary blkankets are concentrated in a paleo-topographic depression along the southern side of the main ENE-trending ridge at Madoonga.
The spatial coincidence of these differing ore types are a major factor controlling the overall size of the Madoonga ore body, but results in a compositionally heterogeneous ore deposit.
This Madoonga summary is drawn from Duuring and Hagermann (2012).
The most recent source geological information used to prepare this decription was dated: 2012.
Record last updated: 30/7/2024
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.
|
|
|
|
Duuring P, Hagemann S G, Novikova Y, Cudahy T and Laukamp C, 2012 - Targeting Iron Ore in Banded Iron Formations Using ASTER Data: Weld Range Greenstone Belt, Yilgarn Craton, Western Australia : in Econ. Geol. v.107 pp. 585-597
|
Duuring, P. and Hagemann, S.G., 2012 - Genesis of superimposed hypogene and supergene Fe orebodies in BIF at the Madoonga deposit, Yilgarn Craton, Western Australia: in Mineralium Deposita v.48, pp. 371-395. DOI 10.1007/s00126-012-0429-0.
|
Duuring, P., Santos, J.O.S., Fielding, I.O.H., Ivanic, T.J., Hagemann, S.G., Angerer, T., Lu, Y.-J., Roberts, M. and Choi, J., 2020 - Dating hypogene iron mineralization events in Archean BIF at Weld Range, Western Australia: insights into the tectonomagmatic history of the northern margin of the Yilgarn Craton: in Mineralium Deposita v.55, pp. 1307-1332.
|
Gole M J, 1980 - Mineralogy and petrology of very-low-metamorphic grade Archaean banded iron-formations, Weld Range, Western Australia: in American Mineralogist v65 pp 8-25
|
|
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.
|
Top | Search Again | PGC Home | Terms & Conditions
|
|
