On 21 August 2014, Ventnor applied for ELA39/1828 comprising 42 graticular blocks situated adjacent to the 7Moz+ Tropicana Gold Mine jointly owned by AngloGold Ashanti and Independence Group. The rationale behind the move was to expand the Company’s focus beyond base metals to gold. The application was granted at the end of March 2015.
The project is located 370 kilometres north-east of Kalgoorlie and 22 kilometres north-east of Tropicana. The tenement has been the subject of recent exploration and since the application was granted, the Company has collated a significant database from previous exploration and has been evaluating the mineralisation potential of the tenement. The database includes assays of soil samples, auger samples, AC, RC, and diamond drilling results, along with a significant geophysical database including gravity/mag and EM surveys. The Company has used specialists to evaluate all of the components of the database and has examined concurrent anomalies.
In adding to the geological knowledge of the tenement Ventnor has been able to reinterpret the regional basement geology, isolating a promising gold anomaly, and identifying an anomalous NiCu zone.
The basement geology has been re-evaluated at project scale using available drill data, and a new interpretation has highlighted an area to the west of the tenement with a subdued magnetic response which coincides with a low embayment in the regional gravity data. The potential for a granitoid intrusion is supported by soil and auger assays indicating the area is depleted in Mg but enriched with Pb, Sb, As and W, which provide fertile ground for further exploration.
The new interpretation has identified three mineralisation styles:
Tropicana Style – Au in K-rich shear zone within high-grade gneisses. Younger than Yilgarn gold and with a limited alteration halo.
Voodoo Child Style — associated with 1750Ma intrusions into localised pull-apart basins, diverse rock assemblage, target structural ‘traps’ in Proterozoic and Archaean rocks, identifiable in magnetics. Other intrusion-hosted potential may exist.
Shear Zone Style – remobilisation of Au, SZ’s identified on magnetics commonly show Au anomalism (e.g., Black Dragon), target second order shears and dilatant zones next to major SZs.
Above: New basement geology interpretation
The Company has identified four prospects at Biranup – Black Dragon, Red Dragon, Silver Dragon and Fire Dragon, as shown on the figure below.
Red Dragon – Gold
Evaluation of the geophysical and geochemistry databases has identified a compelling gold anomaly.
The anomaly is situated within a demagnetised zone with an elevated background of gold in geochemistry. The deepest hole drilled previously within the anomaly is isolated and includes 1 metre at 13.4 g/t Au from 147 metres down a 60o inclined RC hole.
Further work planned includes a gradient array IP survey and drill holes to follow up the previously identified high-grade anomaly.
Silver Dragon – Cu-Ni Anomaly
The Company has identified a magnetic feature north-east of Red Dragon associated with elevated copper, cobalt, and nickel in soil sampling and mafic to ultramafic rocks.
The zoned area has elevated base metals auger geochemistry and ovoidal zoning features in the tilt derivative.
Recent sampling has fingerprinted mafic and ultramafic type rocks. Future work proposed includes a Moving Loop Electromagnetic (MLEM) survey with follow-up drilling on identified targets. The target type is potentially nickel-copper-cobalt sulphides associated with mafic to ultramafic intrusion.
In October 2016, the Company drilled a 286 metre RC drillhole at Silver Dragon. The purpose of the drilling was to test the electromagnetic conductors generated by the recent ground MLEM survey; to ascertain the lithology of the basement rocks; and to allow for a Down Hole Electromagnetic (DHEM) survey to be completed. The mineralisation that is being targeted is magmatic nickel-copper sulphide, similar in nature to IGO’s Nova deposit in the Fraser Range. Assays are pending.
Figure Left: Magnetic reduced to pole image of the Red Dragon area with significant magnetic breaks (faults) in white dash lines. Figure Right: Showing zoomed-in area of a zoned magnetic high.
Fire Dragon – Cu-Ni Anomaly
The Fire Dragon Ni/Cu anomaly is located south-west of the Silver Dragon anomaly.
At Fire Dragon, the ground MLEM survey resolved a strong aerial EM response indicative of a bedrock conductor. Two RC holes were drilled 80 metres apart, to test the strongest modelled response. The holes were drilled to 240m and 264m respectively.
The lithology that was intersected is a metamorphosed, medium grained mafic, with some layers of ultramafic and is believed to have some visual similarities to the upper parts of the Nova mafic intrusive.
In general, the mafic layers were pervasively sulphidic, typically pyrrhotite, but in discrete layers, a significant increase in sulphides of up to 30% (by volume) over one metre, were noted with the presence of chalcopyrite being confirmed by handheld XRF.
The drilling at Fire Dragon has several similarities to magmatic nickel copper deposit, such as IGO’s Nova Bollinger deposit. It is believed that the drilling has only tested the upper layers of the possible mafic intrusion, but the visual identification of chalcopyrite is promising and it is hoped that the upcoming DHEM survey will assist with vectoring into wider accumulations of sulphides.
Drilling to date has confirmed that Fire Dragon is within a sulphidised mineral system, reflecting sea floor black smoker domains which are highly prospective for VMS deposits.