Gold-copper deposits within the SW Pacific Magmatic Arcs have been classified into three main groups by Corbett and Leach (Corbett and Leach, 1997; Corbett, 2009):
• Porphyry-related (including gold skarn).
• High sulphidation gold-copper.
• Low sulphidation (including sediment-hosted replacement).

Telescoping may overprint the varying styles of low sulphidation gold mineralization upon each other or upon the source porphyry intrusion.

Hydrothermal porphyry-related activity in the Kainantu area may have been protracted and associated with more than one intrusive phase (17 Ma to younger than 7 Ma). According to Corbett (2009), while the accepted wisdom is that porphyry Cu-Au mineralization in the Kainantu region is related to Elandora style porphyry intrusions, the coincidence of prograde alteration (Kokofimpa area; K-feldspar alteration) with Akuna-style diorite intrusions suggests alteration and mineralization may have been initiated at an earlier Akuna age and continued to an association with Elandora intrusions. The presence of Elandora clasts within advanced argillic alerted breccias, is consistent with a protracted history of activity. The (17-13 Ma) extended age of Akuna intrusions provides for batholitic intrusions to be overprinted by the mineralized phase recognised herein and distinguished from the younger (9-7 Ma) Elandora-style intrusions. Corbett (2009) recommends limited age dating is conducted once field relationships are e ........

Although longhole stoping represents a considerably larger scale of mining than cut and fill, it is still a relatively selective mining method which allows extraction of high grade, yet relatively narrow, ore zones. The longhole stoping method is based on drilling and blasting ore in vertical rings from drives spaced 20m apart vertically, floor-to-floor, forming stopes 25m high. Stope widths will range from 3m to 15m and strike lengths will vary depending on localised ground conditions.

The average stope width generated using the MSO program is 5.2m, with most stopes less than 8m in width and only 8% of the shapes being greater than 8m wide.

Stopes will be extracted along strike initially in a bottom-up sequence with each stope progressively backfilled for stability and to provide a working base for the next stope above. The Avoca method would be used to limit the strike length of the open stope to maintain stability of the side walls and backs. Stopes will be progressively backfilled from the opposite end to where the stope is being blasted and loaded out.

Where access is not available to both ends of a stope the Modified Avoca method will be used. This method involves tight filling the stope against the ore face after each firing has been loaded out. The next ore blast can be fired against the tight-placed fill, or the fill can be partly mucked out to provide expansion space for the blast. Although Modified Avoca requires less lateral dev ........

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