Ashburton Shire, Western Australia, Australiai

Regional Level Types
Ashburton Shire	Shire
Western Australia	State
Australia	Country

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The Shire of Ashburton is 1400 kilometres north of Perth, and occupies the western half of the Pilbara region. It covers 105 647 square kilometres. In comparison, New York State is 141 300 square kilometres and Portugal
92 212 square kilometres. Population is about 10 000 (August 2011). Apart from Onslow, most of the towns were built in the late 1960's for staff working at the iron ore mines.

The region was settled by Europeans in the 1860's, who set up pastoral stations. Onslow was established as a port for the region in 1865. Little development took place until the late 1960's when large scale iron mines were established in the shire, and later extensive oil and gas fields were discovered off the coast.

The economy of the area is based on mining, oil/gas, salt processing, fishing, pastoral stations and tourism. The central and eastern parts of the shire are very scenic occupying the Hamersley Ranges. The Karajini National Park contains arguably Australia's best gorge country. The Chitchester Ranges and Millstream Oasis are also worthy of investigation. The Tom Price iron ore mine conducts tours of their operations. Roads between major towns are sealed, but beyond this the going gets tough. Please be aware certain parts of the shire are remote and mountainous, and travellers should be prepared.

The geology of the region is complex and volumes have been written about it. Space here largely is limited to naming the rock units. Geologists travel internationally to view the region.

The shire occupies the western portion of the Pilbara Craton, and the Capricorn Orogeny to its south. The Pilbara Craton is one of only two pristine Archaean aged cratons in the world. The craton in the west Pilbara is a granite-greenstone sequence, with a series of layered mafic-ultramafic intrusions, and overlain by an extensive sequence of Archaean and later metasediments. The Pilbara granite-greenstone terrane is a collection of dome shaped composite granite bodies each up to 100 kilometres across. South of the craton is the Capricorn Orogeny containing the McGrath and Ashburton Troughs. Sedimentary rocks constitute this, which has undergone complex structural evolution developing major folds and thrusts.

The lowest unit in the Hamersley Province is the Fortescue Group, then the Hamersley Group, and finally the Turee Creek Group.

The lowest unit in the Fortescue Group is the Bellary Formation of subaerial mafic lava; Mount Roe Formation of again subaerial mafic lava; Hardey Formation of ferrugenous and/or tuffaceous sedimentary rocks, mafic lava, and/or felsic volcanic rock; Boongal Formation of subaqueous mafic lava; Pyradie Formation of subaqueous tuff, mafic lava, spinifex textured basalt and komatiite; Bunjinah Formation of subaqueous mafic lava; and the highest in the Fortescue group being the Jeerinah Formation which in the shire consists of a thick sequence of alternating pillow basalt and dolerite with minor tuff.

The Hamersley Group's lowest member is the Marra Mamba Iron Formation, containing the Nammuldi, McLeod and Mount Newman Members; Wittenoom Formation of carbonate sedimentary rocks; Mount Sylvia and Mount McRae Shale of mudrock, sandstone and shale; the Colonial Chert Member, Brockman Iron Formation containing the Dale Gorge, Whaleback Shale, Joffre and Yandicoogina Shale Members; Weeli Wolli Iron Formation; Woongarra Volcanics; and the highest in the Hamersley Group is the Boolgeeda Iron Formation.

The Turee Creek Supersequence contains siltstone, sandstone conglomerate, carbonate sedimentary rocks, mudrock and sandstone.

In the south and south-west portion of the shire is the Capricorn Orogeny containing the Beasley River quartzite; Cheela Springs basalt, and Wooley dolomite in the McGrath Trough. Mount McGrath conglomerate; Duck Creek dolomite; Ashburton Formation and the Capricorn Formation in the Ashburton Trough. Altogether they form the Wyloo Group.

Specimens from the iron ore mines are rare due to the large scale mining which takes place. Any specimens would normally be destroyed in this process. The south-western portion of the shire contains a number of small historic copper and lead mines. Paulsens is an active gold mine in the area, as well as an amethyst specimen mine at Wyloo. This has historically been operated producing some of Australia's best amethyst specimens. Rare arsenide specimens are seen from Bali Lo, in remote country in the southern part of the shire. The world's best tiger eye is sold widely international from near Mount Brockman. Slabbed rhyolite from Turee Creek, but this is usually only seen in local collections. There is also a jasper lease in the far south-east portion of the shire.

Public fossicking sites are non-existent, but the vast area makes exploration worthwhile. The towns in the shire have limited facilities, and usually no accommodation. There is a specimen shop at Wittenoom. The town was closed and demolished due to the asbestos fibres surrounding it, but the specimen shop refused to go. Visiting the asbestos mine is not recommended.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.

Mineral List

Mineral list contains entries from the region specified including sub-localities

156 valid minerals. 4 (TL) - type locality of valid minerals.

Rock Types Recorded

Rock list contains entries from the region specified including sub-localities