Rory McNeill Reference No. 20148384_7407-012-LR-RevA_DRAFT OceanaGold Corporation 08 September 2021 5 4.0 PRELIMINARY GEOLOGICAL MODEL BASED ON AVAILABLE INFORMATION Conceptual geological long sections for the proposed tunnel alignments 2 and 4 are presented in Figure 4. Figure 4: Conceptual geological log sections for tunnel alignment Options 2 and 4 from Portal to Willows Connection. Both long sections show the shallow and deep tunnel alignments and the geology they intercept (ignimbrite (yellow) and andesite (blue)). Both Option 2 and Option 4 have similar distribution of the various lithological units present. A simplified description of the tunnel geology for the shallow alignments for Options 2 and 4 follows: The geology at the Portal consists of andesite with a surficial volcanic ash layer. With increasing distance to the northeast, they intersect sandy and welded ignimbrites4,5. Once out of the portal the first 300 m of the tunnels will likely encounter ignimbrite and andesite. During this interval, several possible configurations could occur: ▪ There could be single abrupt change from ignimbrite to andesite, ▪ There could be several changes from ignimbrite to andesite and back, ▪ There could be a prolonged mixed face situation with the tunnel encountering both ignimbrite and andesite. 4 Engineering Geology Limited 2020. Proposed polishing pond stockpile geotechnical stability assessment. Prepared for Oceana Gold (New Zealand) Limited, dated 16 November 2020. Ref. 9094. 5 Engineering Geology Limited 2021. Storage 1A – Tailings Storage Facility Raise to RL182 Detailed Design Report. Prepared for Oceana Gold Limited, dated 11 August 2021. Ref. 8981. D R A F T
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