Uranium ore-forming systems of the - Geoscience Australia

Uranium ore-forming systems of the Lake Frome regionAppendix 1: Field guide to the Proterozoic MtPainter Inlier and Mesozoic to Cenozoic basinsof the Lake Frome regionStephen J. Hore and Steven M. HillIntroductionThe Mount Painter region, incorporating the northern Flinders Ranges and western Lake FromePlains, is a world-class uranium province. The region hosts historical uranium workings in theMt Painter - Mt Gee area; one of Australia’s three uranium mines at Beverley; as well as theFour Mile Uranium prospect, which is planned to go into production in 2010. The highlyprospective region hosts both “brownfields” and “greenfields” exploration opportunities.The distribution of uranium in the region is a result of 1600 million years of geology includingprimary U-enrichment within early Mesoproterozoic basement granites and gneisses,uraniferous hematitic breccia systems and subsequent multiple periods of reworking andredistribution up to the present day. Sandstone-hosted uranium deposits within Cenozoicsediments of the Frome Embayment and Callabonna Sub-basin are active mineralising systemswithin an environment characterised by Neotectonic faulting, sedimentation and fluid flow.The Mount Painter region is situated in the northeastern section of the Adelaide Geosynclineand forms the northwestern part of the Curnamona Province. The older metasediments andgranites (the Mt. Painter and Babbage Inliers) have been assigned a Mesoproterozoic age andare intruded by younger, post-Delamerian granites. The inliers are unconformably flanked byAdelaidean metasediments to the west and south, and by Mesozoic and younger sediments tothe east. Historically, the area has been of note more for the diversity of mineralisation (U, Cu,Pb, talc) than its quantity but in recent years there has been active mining of uranium.Despite the Northern Flinders Ranges – Lake Frome Plains region being one of the state’s mostprospective areas for mineral exploration (particularly for uranium), there are still major parts ofthe geological framework that are unresolved including aspects relating to the basement and thesurrounding sedimentary basins. Furthermore, the regolith geology and associated landscapehistory is poorly understood. This is surprising given the dramatic exposures of a wide range ofregolith materials and landforms as well as the importance of this part of the geological historyfor the dispersion, expression and secondary reconcentration of uranium mineralisation. Recentcollaborative research by PIRSA and the University of Adelaide, however, has made somemajor contributions to this geological framework, as well as using this as an important fieldeducation and training laboratory.Uranium has recently increased in importance as an exploration target commodity in Australia.One of the main challenges for this exploration is the detection of buried uraniummineralisation. However, there are increasing environmental and cultural sensitivities related tomineral exploration in areas such as the Frome region, requiring an effective and efficient butalso minimal impact approach. So in addition to geological mapping, sampling andinterpretation, plant biogeochemistry provides a method for obtaining a surficial expression ofburied uranium mineralisation. In general plant roots extend subsurface and chemically interactwith sub-surface substrates. Trace elements may then translocate from the substrate throughPage 120 of 151