Michaelsen, and 5 co-authors, reported in 2016 that The Frome Embayment (Mesozoic) and Callabonna Sub-basin (Cenozoic) that overlie the Curnamona Province (Paleo-Mesoproterozoic) contain South Australia’s richest sandstone-hosted uranium deposits (Figs 1, 2 in article). Arguably, this is the most prospective region in Australia for sandstone-hosted uranium and includes the Beverley deposit (discovered in 1969) and the world-class Four Mile
East and Four Mile West deposits (discovered in 2005).
All sites of known economic mineralisation are within 10 km of uraniferous granite outcrop that is part of the Mount Painter Inlier in the northern Flinders Ranges. The Beverley uranium deposit, a tabular ore body that does not form roll-front geometries (Wülser et al. 2011), is on the northeastern margin of the Poontana Trough (See Figs 3, 4a in article), a 20–40 km wide depression extending for ~150 km NNE–SSW parallel to the northern Flinders Ranges and containing up to 390 m of Cenozoic sediments (Fabris, Gouthas and Fairclough 2010). The latest period of erosion of radiogenic Mesoproterozoic granite (including the Moolawatana Suite, Mount Neill Granite and Radium Creek Group; see Fig. 2) commenced with rapid uplift of the northern Flinders Ranges c. 4 Ma (Quigley et al. 2007). This event is significant in terms of uranium supply to adjacent sedimentary basins.
Airborne radiometric imagery (see Fig. 5) shows that modern drainage transports radiogenic detritus from source regions in the northern Flinders Ranges onto the Frome Plains via channels incised across the Paralana High Plains. The detritus represents a large accumulation of uranium that is potentially available to be remobilized by meteoric water (aka groundwater) and thereby infiltrate local aquifers, from where the uranium is either further dispersed or precipitated and concentrated to form uranium deposits Transoil NL, part of the Oilmin–Transoil– Petromin consortium, which discovered uranium
mineralisation at Beverley, measured concentrations of dissolved uranium in shallow aquifer waters collected from bores across the northern Poontana
Trough (1974 Transoil data in Hore 2008).
Heathgate Resources (1998) published similar data in the vicinity of the Beverley Mine. Values ranged from <1 ppb U near the Beverley deposit and
Pepegoona deposits to a maximum of 900 ppb U in the area between Beverley and Lake Frome (Fig. 5). A corridor of groundwater with low uranium content (≤50 ppb U) lies within ~15 km of the range-front. The authors inferred that reduction of dissolved uranium (as uranyl ions: UO22+) to form uranium ore is most effective within this corridor. By contrast, the Frome Plains, immediately northwest of Lake Frome, currently has no identified economic uranium mineralisation. Groundwater in the region, from available sparse data, is typically high in dissolved uranium (520–900 ppb), with the inference that subsurface reductants, capable of precipitating uranium from groundwater, are either more sparsely distributed or less effective. Organic matter (OM) preserved in the host sediments, together with pyrite derived from sulfate reduction by OM, are widely regarded as primary reductants for sandstone-hosted uranium (e.g. Spirakis 1996). The distribution of OM and its variable capacity to affect uranium reduction are considered prime factors that influence where uranium is deposited and are a key to understanding the region’s prospectivity for sandstone-hosted uranium. On this premise, investigations were commenced to evaluate the OM composition and distribution in sedimentary basins in the region.
The authors concluded, in part, that shallow petroleum systems have generated hydrocarbons (mobile uranium reductant....[CH4 / H2S?]) within the Frome Embayment and Callabonna Sub-basin. In this area, the ‘oil window’ is demonstrably shallow due to elevated heat flow from buried radiogenic Proterozoic granite and elevated temperature gradients in the post-Cambrian succession arising from low thermal conductivities in the pre-Mesozoic sequence. Although aquifer temperature data are sparse, GAB temperatures along the northern margin of the Curnamona Province stand out as being particularly high (52–63 °C) and correspond to the early window for petroleum generation. The highest recorded GAB temperature is from the Woolatchie water bore at the northern extremity of the Poontana Trough where the Terrapinna Corridor separates the Mount Painter and Babbage Inliers.
The Bulldog Shale is likely to be mature for liquid hydrocarbon generation. In addition, six organic facies, summarized in the article, are preserved within Mesozoic and Cenozoic strata overlying Curnamona Province basement rocks. These have varying capacity to generate hydrocarbons that in turn are capable of reducing and precipitating uranium from solution.....[gas/liquid?]
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