EXPLORATION PROJECTS

Yarramba Palaeovalley drainage system

The Yarramba Palaeovalley winds for over 100 km along the eastern side of the Benagerie Ridge. It has no surface expression because it is covered by at least 50 metres of predominantly clayey sediments of the Namba Formation. The palaeovalley generally ranges from 2-6 km wide within Curnamona Energy’s exploration area and is typically filled with 50-60 metres of interbedded sands and clays of the Eyre Formation that were deposited from an intricate network of coalescing river channels as they migrated across the palaeovalley floor. A typical cross-section through the Yarramba Palaeovalley shows three upward fining sequence cycles with coarse sands at the base fining upwards to silty clays (Figure 4).
figure 4
Figure 4
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Several uranium prospects, namely the Honeymoon, Brooks Dam, Yarramba and East Kalkaroo prospects, have been discovered in the Yarramba Palaeovalley 5-20 km upstream from the boundary of Curnamona Energy’s exploration areas. The Honeymoon uranium mineralisation occurs where the lowermost sand layer is confined by an overlying carbonaceous clay and bedrock along the southern bank of the palaeovalley in a typical physical and chemical trap setting (Figure 4).

The orebody extends for almost 1000 metres along the valley wall, is up to 400 metres wide and is about 6 metres thick on average and therefore represents a relatively large exploration target. The chief uranium minerals, uraninite and coffinite, are associated with 2.6% pyrite and 0.3% organic carbon, reflecting the reducing environment of deposition. The Honeymoon and East Kalkaroo deposits also coincidently occur where there is a marked restriction in the width of the palaeovalley as it flows through a narrow gap in a basement ridge, and near to the junction of a tributary stream that drains from an area of uranium anomalous weathered granite to the south. Both of these factors have an uncertain, but possibly important role in the localisation of the uranium mineralisation.

Potentially the Honeymoon style of mineralisation could be repeated anywhere along the 60 km length of the Yarramba Palaeovalley that is within Curnamona Energy’s exploration area. The discovery potential is considered to be good, especially in the lightly explored Mongala section just downstream from Honeymoon.