Geological evolution and economic geology of the Burdekin River region, Queensland

This Bulletin summarises the results of regional mapping by teams of the Bureau of Mineral Resources and the Geological Survey of Queensland from 1961 to 1967 over an area of some 67 000 km2 near Townsville. Small areas of high-grade metamorphics may be Precarnbrian, or may be correlatives of the oldest dated rocks (Late Cambrian to Early Ordovician). These early strata occupied a major east-west basin which was destroyed by orogeny and granitic intrusion in Middle Ordovician time. A further period of granitic intrusion consolidated the Lolworth-Ravenswood Block as a major east-west structural high. Of the Palaeozoic sedimentary basins, the Burdekin Basin received sediments from Givetian to Tournaisian times. Ranging in tectonic activity between a mildly unstable shelf and a yoked intracratonic basin, it presented an alternation of marine and continental conditions as it gradually expanded northwards. South of the Lolworth-Ravenswood Block, a miogeosyncline formed in the Middle Devonian. In the Tabberabberan Orogeny a geanticline rose in the geosynclinal belt, and the Drummond Basin formed on its western side. This transverse basin received sediments from Late Devonian to Middle Carboniferous times in three well-marked cycles, each beginning with torrential sediments and ending with mature ones. In its later life, it possibly emptied into the Burdekin Basin. The Broken River Embayment received sediments more or less continuously from Silurian to Carboniferous times, but only the lowest and highest units occur in the map area. The lowest units are shelf and trough sediments, the highest is shallow-marine and lacustrine. At the latest stage in its development the Embayment reached its greatest extension to the southeast and may have connected with the Burdekin Basin. The Late Devonian to Early Carboniferous sediments and volcanics near the coast represent the northern extremity of a basin probably connected with the Yarrol Basin. These basins were destroyed in the Kanimblan Orogeny, and from Late Carboniferous to Early Permian times the area was dominated by igneous activity. The Bowen Basin developed in the Permian volcanic episode, and passed through a series of marine incursions to a continental environment. Local coastal conditions during the first marine incursion produced the Collinsville Coal Measures. Possible correlatives of Bowen Basin units are widespread, although some of the relationships are tenuous. Triassic orogeny ended deposition in the Bowen Basin, and was followed in the south coastal area by a period of igneous activity in the Early Cretaceous. Quiet conditions followed, and by the end of the Cretaceous the area was topographically mature. In the early Cainozoic some earth movement continued, producing the Hillsborough Basin and resulting in erosion of much Triassic sandstone. The mature topography re-established by mid-Tertiary was the base for the subsequent lateritic episode, interrupted by further erosion and deposition. The evolution of the area was completed by Cainozoic volcanism followed by slight erosion. The physiography of the coastal area is dominated by corridors between high ranges. Faulting can be reasonably suspected as a cause, and in some cases there is some evidence. The inland area is occupied mainly by the Burdekin catchment, which developed its present form by movements in the Cainozoic but still retains some northeasterly trends from Palaeozoic structures.

Tags: AU-QLD, Bulletin, Earth Sciences, GA Publication, Published_External, economic geology, geology
Organization: Geoscience Australia Data