Cummins Range complex (Minneroo Pool), Halls Creek Shire, Western Australia, Australiai

Regional Level Types
Cummins Range complex (Minneroo Pool)	Complex
Halls Creek Shire	Shire
Western Australia	State
Australia	Country

Carbonatite complex, pegmatite-like.

Rare earth oxides are the subject of this exploration. Investigation of the overburden has proved reserves of 4.17 x 10⁶t of REE oxides averaging 1.72%. There are also significant reserves of phosphate, Nb and U.

Cummins Range is 130 kilometres south west of Halls Creek in the Kimberley, and on the northern edge of the Great Sandy Desert. It is very remote desert country, with no access roads or human habitation nearby. The geologists made a note they had to cope with a plague of camels.

The Cummins Range Complex is the name for a small, 1.5km by 1.2km, alkaline intrusive complex, described as a vertical pipe-like pegmatite body. It intrudes the Olympio Formation of sediments and granite, aged 1.8Ma.

The outer zone is unaltered pyroxenite with diopside, biotite, magnetite, apatite, and carbonate, with minor baddeleyite, sphene, ilmenite, monazite, zircon, zirconolite, pyrrhotite, pyrite, and chalcopyrite.

The next zone is mica rich pale green pyroxenite, with coarse biotite-phlogopite, magnetite, carbonate, and amphibole, with minor minerals as mentioned previously as accessory minerals for the outer zone, and in addition, pyrochlore, barite, bastnäsite, aeschynite, and thorianite.

The central core is a carbonatite zone 500m x 400m of dolomite, some calcite and magnesite, and minor amphibole, biotite, magnetite, chlorite, apatite, zircon, monazite, bastnasite, aeschynite, fluorite, pyrochlore, allanite, pyrite, and pyrrhotite.

Apatite occurs as grains less than 7mm and monazite less than 2mm. Oxidation, leaching and dissolution of the carbonates has resulted in the formation of these rare earth oxides, niobium and uranium minerals.

The site has a very interesting geology, and theoretically could produce just as interesting specimens. In reality, only drill holes have happened so far, is on an active lease, and regardless would require a major expedition to retrieve them into harsh desert country with no civilisation for hundreds of kilometres.

Investigation of the overburden has proved reserves of 4.17 x 10⁶t of REE oxides averaging 1.72%. There are also significant reserves of phosphate, Nb and U.

Geochronology

Mineralization age: Neoproterozoic : 905 ± 2 Ma

Important note: This table is based only on rock and mineral ages recorded on mindat.org for this locality and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic Time				Rocks, Minerals and Events
Precambrian
	Proterozoic
		Neoproterozoic
			Tonian	ⓘ Apatite 905 ± 2 Ma ⓘ Phlogopite 905 ± 2 Ma

Other Regions, Features and Areas containing this locality

References