EGL Ref: 9049 23 June 2022 Page 7 File: WAI-985-000-REP-LC-0050-Rev0.docx This report shall only be read in its entirety. The overlying ignimbrites around Waihi are grouped into the Ohinemuri Subgroup consisting of Corbett ignimbrites at 2.9 million years old and Owharoa ignimbrites (late Pliocene) and Waikino ignimbrite at 1.5 million years old (early Pleistocene). Eruptions of ash and pumice blanketed the Waihi area. Typical ash soils found in the area include the Waihi Ash series, the Hauparu Ash and the Rotoehu Ash. The ash mantle at WUG is likely to differ in origin. 3.2. Geology Martha Open Pit to Favona Underground and Gladstone Hill With mining and exploration drilling a good understanding of the geology has been developed from Martha Open Pit to Favona Underground and Gladstone Hill. Figure 5 to Figure 19 show geological maps and sections of the area around Martha Pit and proposed Gladstone Open Pit and Wharekirauponga Access Tunnel, including the various mineralised vein systems. Figure 5 includes the geological map of the area around the Martha Open Pit and proposed Gladstone Open Pit and the location of the cross-sections radiating out from the pits. The cross-sections are given in Figure 6 to Figure 17 and show that the mineralised andesite extends down to at least RL500m (m RL, Reduced Level in Mine Datum). For reference, the ground surface varies from approximately RL1080m to RL1180m around the pits. Figure 19 shows the veins and workings in plan between the Martha and Favona fault and vein systems. Figure 18 shows an indicative geological cross-section from Martha Pit through the Correnso, Trio and Favona fault and vein systems along the same orientation as the lines A-A’ and B-B’ in Figure 19. The section in Figure 18 shows that the andesite (Waipupu Formation) made up of a lower quartz andesite and upper andesite outcropping at the horst (elevated) features of the former Martha Hill (Martha fault), Union Hill (Amaranth fault) and Gladstone Hill (Favona fault). The andesite rock extends to depths greater than 600m and below this a lower volcanic/volcaniclastic sequence is indicated, which is inferred to overlie the basement rock (Manaia Hill Group). The andesites are also host to the ore. Along the top of the Favona fault and Favona and Gladstone vein systems are localised sequences of: • Volcaniclastic deposits (tuffs) (Waipupu Formation) • Hydrothermal (andesitic) vent breccia (Waipupu Formation) See Figure 18. The hydrothermal breccia is encountered on the east side of Gladstone Open Pit. Above Favona Underground both the volcaniclastic deposits and hydrothermal breccia are present in the area where the Wharekirauponga Access Tunnel decline will pass. The hydrothermal vent breccia and volcaniclastic deposits appear localised to the Favona and Gladstone vein systems based on the OGNZL geological model of Waihi (Ref. 26). East from the Favona fault and Favona and Gladstone vein system is a sequence of: • Rhyolite lava flows and tuff (Ruahorehore Rhyolite of Homunga Rhyolite) • Dacite lava flows and breccia (Uretea Formation – Black Hill Dacite)
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