An operating coal mine near Collie. The open pit strip mining covers a large expanse of countryside trending north-west to south-east, about 15 kilometres east of Collie, and directly south of the Coalfields Highway. Locally also known as Muja, after the power station at the mine's southern end. A huge dragline is publically displayed along the highway.

Muja is an indigenous word for Christmas Tree. This does not relate to pine trees of yuletide, but Nutysia floribunda, the largest species of mistletoe in the world, native and common to south-western Australia. This parasitic plant forms a tree up to 10 metres high, covered in vivid orange-yellow flowers from October to January. In a former life I was part of a telecommunications company, and we would have all sorts of problems with the roots of the trees straggling underground telephone lines.

The mine opened in 1966. Over 55 coal seams are known in the Collie Basin. Muja contains Bellona, Ceres, Diana, Eos, Flora, Galatea, Iona, and the largest Hebes coal seams. Irregular coaly rootlet dykes pass gradually upwards into the seams. The northern portion of the mine, known as Premier contains coal seams named Premier one to eight.

The coal is formed in a sequence of sandstone and claystone with a laterite hardcap above called the Nakina Formation. Only microflora fossils have been found. Above this is up to 20 metres thick overburden of sand, silty clay, and clay, similar in colour to the Collie Coal Measures.

The Collie Basin is in the south-west portion of the Yilgarn Craton. Permian sediments within the basin are covered by an irregular thick blanket of sandstone, minor clay, lag gravel, and lateritic hardcap, Cretaceous to Holocene. The oldest rocks is the Stockton Formation, overlain by the Collie Coal Measures up to 60 metres thick in the Premier area.

The formation consists of bluish grey claystone, with minor amounts of schist and pale cream or white sandstone. Near the base is poorly sorted matrix supported pebbles and cobbles of dolerite, quartzite and granitoid.

The Collie Coal Measures from its base is sandstone, siltstone, claystone and then coal, 5 to 15 metres thick each.

Regions containing this locality

Australian Plate (Australia Plate)	Tectonic Plate
West Australian Element, Western Australia, Australia	Craton
Yilgarn Craton, Western Australia, Australia	Craton
Collie Basin, Western Australia, Australia	Basin

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Neogene - Early Cretaceous 2.588 - 145 Ma ID: 914514

Nakina Formation Age: Phanerozoic (2.588 - 145 Ma) Stratigraphic Name: Nakina Formation Description: Weakly lithified claystone, conglomerate and sandstone in upward-fining cycle; cross-bedded, fluviatile sands. Comments: regolith; synthesis of multiple published descriptions Lithology: Regolith Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia). [5]

Neoarchean - Mesoarchean 2500 - 3200 Ma ID: 3189638

Archean crystalline metamorphic rocks Age: Archean (2500 - 3200 Ma) Comments: Yilgarn Craton Lithology: Amphibolite/granulite grade orthogneiss Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

External Links