Two regionally significant periods of coal deposition occurred in the Galilee Basin, initially in the Early Permian followed by a more extensive Late Permian episode. These coal-forming events were interrupted by a major depositional hiatus in the Middle Permian (Wells, 1989). Across most of the Galilee Basin the Permian strata are unconformably overlain by younger rocks of the Jurassic to Cretaceous Eromanga Basin, except in an arcuate zone on the eastern basin margin (as shown in Figure 18 of product 1.1 for the Galilee subregion (Evans et al., 2014)). It is only along the far central-eastern and north-eastern margins of the Galilee Basin that coals are likely to be mined in future, due to their relatively shallow depth below surface.
The focus of this section is on the four main coal-bearing geological formations that occur within the Permian strata of the Galilee subregion (Figure 3 and Figure 4), namely the:
- Aramac Coal Measures (Early Permian)
- Betts Creek beds (Late Permian)
- Colinlea Sandstone (Late Permian, stratigraphically equivalent to the lower part of Betts Creek beds)
- Bandanna Formation (Late Permian, stratigraphically equivalent to the upper part of Betts Creek beds).
Additional to these Permian coals, low rank coals occur in rocks of the Rolling Downs Group within the Eromanga Basin. These commonly overlie the Permian and Triassic strata of the Galilee Basin and are mostly hosted in the Cretaceous Winton Formation (Figure 4). These Mesozoic coal resources within the Galilee subregion are also briefly described within this section.
Figure 3 Interpreted distributions of Permian coal-bearing formations in the Galilee Basin
Source data: derived from data described in Scott et al. (1995)
Figure 4 Stratigraphic frameworks of the Galilee and Eromanga basins, Queensland
