The Galilee Basin covers an area of approximately 250,000 square kilometres in Central Queensland. It is an intracratonic basin and is filled with Late Carboniferous to Middle Triassic sedimentary rocks. These rocks are predominantly of fluvial origin, with minor glacial material occurring towards the base of the succession.
The basin is almost entirely unconformably overlain by the Jurassic-Cretaceous Eromanga Basin. Only along the eastern margin are Permo-Triassic rocks exposed in a long, narrow gently curved belt. The maximum known stratigraphic thickness of the basin is 2,820 m. The basin is divided into the northern and southern parts by the east-west trending Barcaldine Ridge located at approximately 24 degrees south.
The stratigraphic succession of the Galilee Basin is partly related to stratigraphic successions in the Cooper and Bowen Basins, with each basin having experienced a hiatus during some part of the middle Permian). Major coal deposition occurred in the Galilee Basin during the Early Permian in the Aramac Coal Measures, as well as during the Late Permian in the Colinlea Sandstone and Bandanna Formation and their correlatives, the Betts Creek Beds.
In the vicinity of EPC 987, with the exception of a narrow strip of outcrop along the north eastern and eastern margins of the basin, the stratigraphic sequence is overlaid by Jurassic and Cretaceous sediments and in place by thick Tertiary semi- consolidated sediments. The Permian sequences, identified through surface mapping and drilling in the eastern margin of the Galilee Basin have been summarized in the Table Below.
Coal is present in both the early and late Permian sequence of the Galilee Basin. The early Permian coals in the youngest formation of the Joe Joe Group, the Aramac Coal Measures are restricted to the northern Galilee Basin.
The Joe Joe Group is mainly comprised of fine grained sandstone, siltstone, lithic quartz sandstone, carbonaceous shale with coal seams, and locally with limestone. Existing borehole loggings and seismic surveys indicate the sequence is approximately 270 meters thick, of which it is estimated 25 meters are coal seams.
The late Permian coal measures are widely spread. The coal occurs in the Colinlea Sandstone, Bandanna Formation and their equivalent. The sequences are mainly sandstone (up to 49%), shale and siltstone, and contained coal seams. The coal seams in this sequence are thickening to the east, but are generally consistent across the eastern basin. Within the lease areas the coal seams are predicted to be approximately 30 metres thick in the lease areas.
The Later Permian Bandanna Formation coal measures dip about 3°~5° W and no major faulting is present. Overlying the Joe Joe Group is extensive semi- consolidated Tertiary sediment cover which is generally around 20 metres thick, but which extends to 100 m thickness in the eastern portion of the lease.