Silver City Minerals Ltd (ASX:SCI) has confirmed the presence of a large system of iron oxide copper-gold (IOCG) style in drilling at the Copper Blow project south of Broken Hill.
Two diamond drill holes in phase IV of drilling intersected mineralisation and are now being logged and sampled with analytical results likely to be available in late October or early November.
READ: Silver City Minerals has drill spinning targeting new copper-gold mineralisation at Copper Blow
A hole in the main Copper Blow shear zone (18CB071) intersected 70 metres of magnetite-quartz-sulphide rock from 367 metres.
It also intersected two new zones of mineralisation higher in the hole – 14 metres from 171 metres and 22 metres from 236 metres.
Another hole (18CB072) at the Southern Anomaly intersected extensive sulphide with a total of 230 metres of disseminated and veinlet sulphide.
One zone extended for 160 metres from 40 metres and the other for 70 metres from 308 metres.
A simplified geophysical map showing the results of dipole-dipole and gradient array surveys.
Both zones are associated with biotite alteration and the lower intersection is preferentially hosted in metamorphose volcanic rocks.
Considered to be IOCG type
Silver City believes that mineralisation is considered to be of the IOCG type, similar to Olympic Dam.
If this is the case, Copper Blow would be the first IOCG deposit identified in NSW.
Hole 18CB071 was designed to test for deeper extensions to the copper-gold mineralisation outlined by previous drilling at Copper Blow with this mineralisation hosted in a strongly magnetic ironstone.
The target structure was intersected over a broad zone, which tends to indicate that the mineralised structure dips to the southeast and flattens with depth.
Neither the magnetite nor the sulphide content in this main zone is as elevated as intersections higher in the structure.
Two new zones
Two new zones of mineralisation have been identified higher in the hole and these are to the southeast of Copper Blow.
18CB072 was designed to test a large IP chargeability anomaly coincident with anomalous soil geochemistry.
READ: Silver City Minerals rock chip assays reveal high-grade copper cobalt targets
There had been no previous exploration drilling in this area, which is about 800 metres southeast of the Copper Blow deposit.
This hole contains a remarkable amount of very fine-grained, disseminated and stringer sulphide which accounts for the IP anomaly.
IP responds particularly well to this style of sulphide mineralisation.
The dipole-dipole model depicting a horizontal slice of IP chargeability at 180 metres below surface.
The volcanic-rich sequence in the lower part of the hole probably explains the gravity anomaly in this zone because these rocks have a higher specific gravity than the enclosing sediments.
This form of sulphide mineralisation is reminiscent of that which occurs in association with IOCG systems and/or porphyry copper deposits.
READ: Silver City Minerals chairman shows faith in company by acquiring further shares on-market
It is the view of Silver City geologists that major crustal structures such as the Copper Blow shear zone, have a higher propensity to host significant copper-gold mineralisation compared to zones devoid of structural breaks.
The company will continue to focus work close to the main structure and will test geophysical and geochemical anomalies in the Northern Target zone as soon as possible.