ASX-listed Si6 Metals is neck deep in a ground geophysical survey at its Dibete, Airstrip and Maibele North prospects in eastern Botswana. Previous similar surveys have successfully mapped and extended existing nickel-copper sulphide mineralisation at Maibele North which boasts a 2.38 million tonne resource grading 0.72 per cent nickel and 0.21 per cent copper. Si6 is preparing a drill campaign to test the new targets.
The company is actively exploring for base and precious metals within the Limpopo Mobile Belt in Botswana, a district known for hosting major nickel and copper deposits including the Selebi Phikwe nickel-copper deposit with an estimated historical resource of 150 million tonnes grading 1 per cent nickel and 0.9 per cent copper.
The company has been using geophysics to identify deeper sulphide targets for drill testing at its 60 per cent owned Maibele North, Airstrip and Dibete prospects at its Maibele nickel-copper project. Such techniques include induced polarisation – “IP” and audio frequency magnetotellurics – “AMT”.
According to the company, the IP surveys at Airstrip and Dibete successfully identified several promising targets to a depth of about 120 metres while the AMT survey at Maibele North mapped known sulphide mineralisation and detected significant responses down to a vertical depth of around 1km.
Encouraged by the effectiveness and depth penetration of the AMT technique, Si6 says it is now undertaking a further survey across the three projects to generate deep targets in the areas of strong IP response at Dibete and Airstrip and it is looking to close off existing open anomalies at Maibele North.
The resource at Maibele North covers 800m of strike with nickel-copper sulphide mineralisation said to continue for a further 475m to the north-east and 125m south-west. The deposit is also open at depth.
Previous AMT geophysical surveying at Maibele mapped the known sulphide mineralisation and unveiled several significant zones of anomalism beneath the known orebody. Strong responses detected to the immediate northwest of the resource and northeast of a recent diamond drillhole that intersected 0.42m of sulphide mineralisation grading 0.12 per cent nickel and 0.08 per cent copper sulphides remain open at depth and unsurveyed.
The company says the current AMT program will cover the known extensions and look to fully define their extents to aid with drill hole planning.
The survey also took in part of the nearby Airstrip prospect to the south-west where historical drilling returned some eye-catching hits including 8m at 10.39 per cent copper and 630 grams per tonne silver from 52m.
Management reported a small but strong response from the survey at depth suggesting potential for a deeper source of the mineralisation at Airstrip.
A further 10 AMT lines have been planned across the anomalies according to Si6, with the outcomes forming the basis for an extensive regional reverse circulation drilling program designed to test the new targets at depth.
Si6 defined a 2.5 kilometre long coincident IP anomaly at Dibete that lies beneath and along strike from past shallow copper-silver drill intercepts that included 25m at 2.17 per cent copper and 77 grams per tonne silver from 27m and 17m at 2.7 per cent copper and 40.5 g/t silver from just 16m. Geological modelling of the mineralisation by the company suggests a deep-seated source.
A further 13 AMT lines are now planned across the anomaly to identify the possible sources of mineralisation and generate drill targets.
With its saddle bags brimming with a plethora of untested anomalies, Si6 has commenced discussions with local drilling contractors as it builds a case to wheel out the truth diviner at its interesting Botswana play.
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By Matt Birney
