June 2022 G-14642.71-006-R-Rev0_FINAL 23 Drillhole interval (m) Geological description Geotechnical characteristics Comments 785.0 to 820.15 Porphyritic ANDESITE Highly variable rock Made up of 6 andesite flows of varying weathering and rock mass strength 820.15 to 990.4 Lapilli TUFF Moderately weathered, weak rock 33.8 m of TUFF breccia between 95.6 – 990.4 m 990.4 to 1043.5 (EOH) Porphyritic ANDESITE Moderately weathered, weak-moderately strong rock Slightly weathered, very strong from 1026.8 – 1043.0 m Notes: ANDESITE is a fine grained extrusive volcanic rock; TUFF is a rock comprising pyroclastic volcanic ash that mainly comprises sand size or finer material; LAPILLI TUFF is a tuff that contains up to 50 % of rock fragments greater than sand size; TUFF BRECCIA is a pyroclastic rock that comprises more than 50 % of angular rock fragments in a tuffaceous matrix. WNDD008 encountered predominantly volcaniclastic tuff breccias (Figure 13) and flow andesite (Figure 14), with major lithological units typically in the range of hundreds of metres in core length. Unit thickness in the core is interpreted to be exaggerated and does not represent true thickness as WNDD008 was drilled at an inclination of about 20°, which is inferred to be at a low angle compared to the orientation of unit boundaries. Andesite lava flows show relatively thin (metres thick) zones of highly weathered material near contacts with tuffaceous material. Tuffaceous units show low strength and a high degree of weathering. Lapilli tuff material was retrieved as gravels (e.g., 380 m - 450 m) (Figure 15) which may be an indication of weak matrix strength. Joint orientations within WNDD008 show a dominant northwest strike, steeply dipping to the north east at approximately 70° - 80° (inferred by the logger using oriented core techniques). This orientation is concordant with regional structural trends. Shallow dipping (less than 20°) discontinuities are rare in the core logs, which is consistent with a low angle hole orientation, which would likely not intercept near-horizontal joint sets. WNDD008 does not show the shallow east dipping orientated joint set of WNDD007 trend. Discontinuities tend to be widely spaced (600 mm – 2 m), although up to 10 m-long closely spaced jointed (60 mm – 200 mm) sections occur within the porphyritic andesites. Discontinuities within the lapilli tuffs and tuff breccias are widely spaced (600 mm – 2 m). There are no recorded joints in a 50 m section of core between 370 m and 430 m.
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