D’Arcy, Bill1, Winter, George1
1Member (Retired), Geological Society of Australia
The 161-km Brisbane Valley Rail Trail (BVRT) and the 88-km Kilkivan-Kingaroy Rail Trail (KKRT) were established along disused branch lines of the railway network of SE Queensland; linking them together is the 55-km Yarraman-Kingaroy Link Trail (YKLT). We logged the geology along this 305-km recreational trail on behalf of the Geological Society of Australia (GSA) – Qld Division. Tectonic terrains encountered include a Late Paleozoic accretionary complex formed during westward subduction of the proto-Pacific under the eastern margin of the Australian proto-continent, and Carboniferous to Triassic volcanic and plutonic rocks of an associated volcanic arc; these are elements of the New England Fold Belt, and form a basement to the Esk Basin, a half-graben overfilled with Triassic volcanics and volcaniclastic sediments. The above-mentioned units in turn are partially overlapped from the south by Mesozoic elements of the terrestrial Clarence-Moreton Basin, which overlies the Ipswich Basin, host to formerly-important coal measures around Ipswich (but not exposed on the trail route). Extensive Paleogene (probably Oligocene) terrestrial basalt flows are crossed along some northern segments of the route. Cenozoic units are mostly alluvium deposited in the modern river network, and minor swamp and lake sediments.
GSA member Warwick Willmott has condensed our detail logs of the BVRT and KKRT to concise brochures compatible with the Rocks and Landscape Notes series, which can be downloaded without charge from the GSA website. We have begun work on compiling the geological features along the YKLT (logged in mid-2020), for inclusion in this series of brochures. The brochures were written for readers with little or no formal geological education, and describe outcrop-scale features exposed along the route, as well as the regional-scale geological factors that influence the landscape, including the evolution of the fluvial drainage network to its current configuration. We also describe a few localities that are close to the trail, and have significant geological interest. Copies of the BVRT and KKRT brochures were delivered in July 2020 to Municipal Visitors’ Information Centres, and cafes popular with trail-users along the route.
Both presenters are retired graduates of University of NSW. Bill has a background in academia, gold and base metals exploration, and open pit gold mining. George has a background in metallic minerals exploration, metallogenic mapping and civil engineering materials.