Surat Basin

In the Surat Basin, the Middle to Upper Jurassic Injune Creek Group, which consists of lithic sandstone, siltstone, mudstone and coal contiguous with the Clarence-Moreton Basin across the Kumbarilla Ridge, provides a major coal sequence in the Maranoa-Balonne-Condamine subregion. The thick sequence of interbedded coal and sedimentary rocks comprises of two coal groups: the Juandah Coal Measures and the Taroom Coal Measures (Queensland Government EHP, 2013, p. 32), both part of the Walloon Coal Measures.

In a study by Scott et al. (2007, p. 7) the Jurassic coals of the Surat Basin were described as dull, and rich in carbon (>80% dry, ash-free (daf)), with high volatile matter content (>30% as received (ar)) and moderate to high ash yield ( 30% ar). Coal rank ranges from sub-bituminous to high‑volatile bituminous (Scott et al., 2007, p. 7).

The major coal deposits of the Walloon Coal Measures occur in the Macalister, Brigalow and Chinchilla areas in the subregion (Goscombe and Coxhead, 1995, p. 505). The Juandah Coal Measures in the Macalister area contain six coal seams with a mean aggregate thickness of 8 m. At the Brigalow deposit on the western flank of the Kumbarilla Ridge, the coals of the Juandah Coal Measures contain two economic seams of interest, the uppermost of which has a maximum and mean thickness of 16 m and 10 m, respectively, and mean in situ ash of 28% (Goscombe and Coxhead, 1995, p. 506). Several deposits of the Juandah Coal Measures occur in the Chinchilla area, where washed ash yields are about 12% and volatile matter contents are about 42%. At Sefton Park and Rywung, the coal measure sequences contain two banded seams 1.5 to 5.8 m thick, and economic coal resources are also present at Glen Wilga, Haystack Road and Horse Creek (Goscombe and Coxhead, 1995, p. 506). In the Wandoan area, three seams are typically present in the Juandah Coal Measures, with individual seams 1 to 6 m thick (Goscombe and Coxhead, 1995, p. 506). These occur at about 80 m depth. Washed ash yields in the Wandoan area are about 9% and volatile matter contents are about 44%. Approximately 70 km north of the subregion in Taroom, the Taroom Coal Measures have two coal seams of economic interest: an upper and a lower seam with mean thicknesses of about 5 m, and 2 to 3 m, respectively. Some of the coal resources in this area occur within 60 m of the surface (Goscombe and Coxhead, 1995, p. 506) and extend south into the subregion past Chinchilla.

At a proposed mine site called ‘The Range’ (see Section, coal is typically situated at shallow depths, and coal mining will require only open-cut methods for extraction of coal from seams located from 20 to 120 m below the surface (Queensland Government EHP, 2013, p. 2). Further south at Kogan Creek, coal has minimum depths of 12 to 15 m below the surface (CS Energy, 2013, p. 2). The three main seams at Kogan Creek have a total thickness of 12 m, and dip gently towards the south-west in seams of 0.1 to 3 m thickness (CS Energy, 2013, p. 2).

Last updated:
5 January 2018
Thumbnail of the Maranoa-Baloone-Condamine subregion

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