S2 Resources (ASX: S2R) reports that the first diamond drill hole has started at its Glenlogan project in the Lachlan Fold Belt of New South Wales, where it is earning up to an 80% interest from Legacy Minerals.
The hole, SGLD0001, is designed to test a prominent magnetic anomaly modelled as a vertically oriented columnar body and interpreted to be a potential copper-gold porphyry target.
The collar of this hole is situated some distance to the southwest of the centre of the magnetic anomaly and has been designed to drill to the northeast with a relatively flat trajectory in order to pass through both the vertically oriented magnetic body and any enveloping alteration and/or mineralised zones surrounding it.
It is anticipated that the hole will be >1,000 metres in length, passing through the modelled core of the magnetic body at a depth of 550 to 600 metres below surface.
Porphyry copper-gold deposits form in association with porphyritic igneous intrusions and may occur within the intrusions themselves and/or in adjacent country rocks. The intrusions are often pencil or finger shaped, with a variety of broadly concentric alteration zones.
Mineralisation, if present, usually takes the form of iron and copper sulphides disseminated throughout the rock and within swarms of quartz veins, and it may form within and/or outside the porphyry intrusion, in various alteration zones which may be magnetic (due to the presence of hydrothermal magnetite in association with the sulphides) or non-magnetic (due to the destruction of primary igneous magnetite by the same hydrothermal fluids).
For this reason, it is important when drilling to ensure all of these scenarios are tested, which is why this hole is designed in this way, rather than drilling vertically down the axis of the magnetic body.
In the event that there is a complex sequence of multiple crosscutting intrusions and/or overprinting alteration zones, the targeted copper-gold mineralisation could be focused in any one of several intrusions and/or alteration zones (and not necessarily the magnetic zone), so the first hole may not necessarily provide a definitive outcome.
To anticipate this, a second hole has also been planned, which will approach the target from a different location and direction in order to test a broader zone around the magnetic body.
