Skipton, Victoria, Australia
The Skipton Exploration Licence, EL5172, is wholly-owned by PD. Historic gold production in Victoria is substantial, most of which was derived from Western Victoria. Furthermore, Victoria’s undiscovered gold endowment in covered areas is also considered to be substantial. PD’s exploration in Victoria is aimed at identifying opportunities for multi-million ounce gold discoveries under cover.
Most of the EL is mapped as Tertiary volcanic cover (Figure 1) of variable and uncertain thickness. The geological log of a State Observation Bore in the centre of the EL suggests that the cover depth there is approximately 120m.
It is believed that the EL has never been explored for a primary gold deposit. The Beaufort alluvial gold field which trends southwards into the north-east corner of the EL, up to the edge of the volcanic cover, provides some supporting evidence for the gold potential of the covered area within PD’s ground.
The Skipton area was selected by the PredictoreTM methodology as having significant potential for discovery of a large gold deposit under cover. Wavelet analysis of Government gravity data is interpreted to have revealed a relatively subtle north-east oriented structural feature connecting the Skipton area to the Bendigo gold field. In addition, examination of State Government geological maps showed that there is a change from younger to older granites across a line that coincides approximately with the interpreted feature. Taking both lines of evidence together, PD has formed the view that a long and very deep seated structure may be present along this line and may have played a role in the formation of the giant Bendigo gold field. The same wavelet analysis data set also suggests that a very long and deep north-west oriented feature connects the Skipton area with the Stawell gold field. EL5172 was taken up to cover the intersection of these two features.
The rocks beneath the volcanic cover at Skipton are interpreted to be the same age and approximate composition as the host rocks at the 5 million ounce Stawell gold deposit to the north-west. There, the bulk of the gold mineralisation is located close to the boundary between a dome-like basalt body and the surrounding rocks. Earlier fluid modelling work has shown that the difference in rock properties between the basalt and the surrounding rocks, combined with the geometry of the contact, were probably the main controls on the localisation of focused fluid flow that formed the ore deposit.
At Skipton, PD’s conceptual target is in a similar geological setting to that of Stawell. PD’s first priority has been to determine if a similar basaltic rock mass could be present below the volcanic cover. PD’s initial gravity survey in March-April 2010 is interpreted to have indicated a northerly trending residual gravity anomaly that may be a basalt body within the EL (Figure 2). PD’s exploration strategy is to define the shape and position of the possible basalt body with detailed geophysical surveys and then determine the best possible drill target through PredictoreTM fluid flow modelling.
PD regards the Skipton EL as a high risk but potentially high reward exploration opportunity. It is located in a fertile gold belt that has yielded a very large quantity of gold from predominantly high grade ore deposits. The area was selected using the principles that guide PD’s exploration philosophy, and specifically the identification of large structures that may have controlled the location of large orogenic gold deposits.
Figure 2: Residual gravity anomaly identified by PD gravity survey at Skipton. The warm colours indicate a possible dense north-west trending underlying rock mass. PD postulates that the source of all or part of this anomaly may be a Cambrian basaltic body located beneath the volcanic cover shown on Figure 1.
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