The resumption of brownfields mineral exploration at the historic Kapunda copper mine and nearby prospects, undertaken by a new company, has targeted previously identified copper geochemical anomalies lying on the abandoned mine leases and along...
The resumption of brownfields mineral exploration at the historic Kapunda copper mine and nearby prospects, undertaken by a new company, has targeted previously identified copper geochemical anomalies lying on the abandoned mine leases and along structural/stratigraphic features recognised at some distance to the north, east and west of these leases. Detailed geological mapping at 1:4800 and 1:1200 scales, plus much rock chip sampling and re-logging/re-assaying of existing drillhole stored samples, was carried out in the centre and on the eastern side of the Kapunda fault-breached anticlinal 'Dome', which disclosed elevated copper values disseminated within three Adelaidean units that lie near the base of or immediately below a thinned Tapley Hill Formation section. Reconnaissance stream sediment sampling and 1:9600 geological mapping was conducted over the whole licence area and was followed up by sampling of residual soils and rock outcrop, then by auger geochemical sampling of the bedrock beneath resultant anomalies (262 auger holes for 5240 feet total penetration), and finally by limited percussion drilling (11 holes for 2750 feet total penetration). This work showed that mineralisation of possible epithermal origin, but with some syngenetic component, is confined to the rocks occurring north of the River Light, particularly in the vicinity of the Kapunda 'Dome', and also adjacent to the Bremer Fault zone. The mineralised conjugate fracture sets examined at the Morphett mine prospect and at the Stephens mine prospect appear to have almost the same orientations as those present at the Kapunda mine, but are sub-economic for copper and have no other associated trace metals of interest, although one percussion drill cuttings sample did return minor gold (0.55 ppm Au). Some minor but significant copper and nickel mineralisation is related to basic dykes which intrude Cambrian carbonate rocks immediately to the west of the Bremer Fault, and it is thought that this setting may be somewhat similar to the lode situation seen at Burra. Disseminated, banded mineralisation formed in a tremolitic marble band up to 16 feet wide was once worked here at the Allen's Creek mine. It has been recommended that further work be focussed on identifying possible extensions to the Kapunda mine lodes of oxide and supergene sulphide copper ore that may carry northwards into the town precinct, besides evaluating the strong geochemical anomaly noted within the Tindelpina Shale Member along the axis of the Kapunda 'Dome'.
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