Nuku Project
During early 2007 regional geochemical sampling of SPL1368 was undertaken and numerous areas shedding anomalous gold and base metals were defined. One of these, the Wailoaloa Prospect is located on the northern part of an anomalous, highly magnetic zone which forms a SW trending anomaly over approximately one kilometre.
Modelling of data collected during a helicopter borne magnetic survey undertaken by CRA Exploration Pty Ltd during 1991 showed that this feature is caused by a shallow SE dipping and strongly magnetic source. At Wailoaloa outcropping zinc mineralisation with assays ranging to 12.75% zinc were located by Geopacific near the western end of gossanous and mineralised outcrop. During early 2007 a ground magnetic survey was completed over the eastern end of the gossanous zone and this work showed that the mineralisation dips towards the south at a shallow angle (Figure 1).
Mineralisation is hosted by volcanoclastic sediments close to the contact with granodiorite and is typical of a polymetalic skarn deposit with high zinc, gold, silver, manganese and iron.
Diamond drill hole WL8 (angled towards 020 degrees magnetic at a dip of 60 degrees and drilled to a depth of 25m) was undertaken by CRA Exploration Pty Ltd in 1991 and intersected 8m of 5.1g/t Au from 12m down hole.
The anomalous gold mineralisation in WL8 occurs within oxidised and clay altered magnetite skarn* and hornfels* immediately beneath outcropping gossan. Recoveries of drill core sample of WL8 were very poor and base metals were not assayed by CRA Exploration Pty Ltd.
Geopacific completed two diamond drill holes (DDHNW01 and DDHNW02) at the Wailoaloa Prospect. Both were positioned to test for skarn-hosted sulphide mineralisation down dip from the anomalous gold reported in drill hole WL8 and the anomalous zinc values in the outcropping hornfelsed sediments which host the known surface mineralisation (Figure 2). Collar coordinates of both holes are listed in table below.
Both drill holes penetrated calcareous sulphide skarn mineralisation beneath strongly fractured granodiorite. DDHNW01 intersected magnetite-pyrite-garnet-epidote skarn between 17.35m and 42.7m and thirty samples of sawn drill core over this 25.35 metre interval were selected for sample preparation at the Westech Vatukoula laboratory.
DDHNW02 was drilled beneath DDHNW01 from a location 50 metres to the south of DDHNW01. Similar skarn mineralisation, including zones of massive magnetite and pyrite, were intersected between 41.8-63.85m and underlying calcareous sediments were intersected until the bottom of DDHNW02 at 83.1 metres. Base metal analyses for core samples from both DDHNW01 and DDHNW02 are being undertaken by Intertek, an accredited Jakarta based laboratory, and the assay results are expected during early 2008.
Both drill intersections of magnetite skarn are consistent with an interpretation of a shallow, south-east dipping zone of magnetic source rocks. Regional magnetic data indicate that these rocks could extend over a strike length of about one kilometre. Since the drilled intervals of skarn in both DDHNW01 and DDHNW02 are close to true widths and the specific gravity of the mineralised sulphide rock is high (3-5), the Wailoaloa Prospect has the potential to host a deposit of several million tons.
The occurrence of high gold values (8m of 5.1g/t Au in WL8) in oxidised gossan which overlies the base metal–rich polymetallic skarn mineralisation at Wailoaloa is not uncommon in tropical, high rainfall environments like Nuku. Deeper sulphide mineralisation is unlikely to have gold values of equivalent
grade although gold may be a significant component.
Further follow-up drilling at Wailoaloa is planned.