Summary:
The geology proximal to the Terakimti deposit comprises a northeast trending, central belt of intermediate porphyritic metavolcanic rocks flanked to the north by Neoproterozoic metasedimentary rock and granodiorite, and to the south by intermediate to mafic volcanic rocks. Significant chlorite, sericite, and silica alteration is associated with conformable gossanous horizons associated with the contact area of the intermediate and felsic volcanic rock packages, quartz-eye volcanic rocks and intrusive rocks are also present in this altered zone. The gossans are associated with polymetallic massive sulphide (gold- silver-copper-lead-zinc) mineralization at depth. Magnetic cherts are noted in the gossan area. The rocks have been affected by intense deformation, resulting in the development of a penetrative fabric in all lithologies, but in particular those rich in sericite. Local folding is present, but large- scale folds have not been identified.
The largest known economic occurrence on the Harvest property is the Terakimti deposit, a Neoproterozoic volcanogenic hosted massive sulphide discovery. Extensive drilling at 40 m by 40 m to 40 m by 80 m drill spacings (20 m by 20 m in oxide), it is currently defined as a moderate-sized relatively high-grade copper- gold-silver-zinc-lead occurrence containing multiple stacked lenses over 800 m strike and defined to depths f at least 260 m below surface. It is hosted within a bimodal volcanic sequence of intermediate and mafic volcanic (including pillow basalt) to volcanoclastic rocks. Numerous quartz-eye porphyry dykes intrude the centre of the mineralized system but the timing relationship is unclear (coeval to postdating mineralization). The VHMS is interpreted to be located along a syn- sedimentary fault, reactivated during regional compression, which cross cuts stratigraphy. The fault zone is defined in surface mapping as a zone of shearing and brittle faulting further northeast. In section, the interpreted fault zone includes sulphide breccia, porphyry and aplite dykes, jasperoid alteration of host rocks and laminated ore types.
Mineralization along the fault zone dips southeast at 40° to 90° and plunging at 20° to 40° degrees toward 073° to 090°. Bedding in the surrounding rocks generally dips 40° to the east, with open to tight folding observed. The Terakimti VHMS is interpreted to lie on the west limb of a regional tight syncline.
The Terakimti VHMS system consists of at least four stacked lenses containing copper-gold-silver and variable zinc-lead:
• The Southern Lens is up to 50 m in true thickness, at least 360 m in strike, and up to 170 m high. It has a massive pyrite base up to 5 m thick and is a mound shaped lens. It is significantly supergene affected (upgraded) at the southern end of the north-northeast plunging Terakimti System. The peak primary sulphide intercept includes 73.85 m. The Southern Lode consists of massive fine-grained pyrite, with coarser grained chalcopyrite and lesser sphalerite as interstitial fill, pyrite replacement and fracture fill. Its average density is 4.07 (SG), including barren thin felsic intervals. It plunges at 20 to 45°.
• The Central Lens sits structurally above and flanks the Southern Lens, is up to 150 m high (dip component), up to 15 m in true width (averages 8 to 10 m) and is currently defined over 480 m down plunge (open down plunge). This lens is well banded in places, somewhat tabular and reasonably predictable. The Central Lens is directly overlain by the hanging wall basalt, which is carbonate and jasperoid altered near sulphide mineralization. The peak diamond drillhole intercept is 15.2 m. The peak reverse circulation oxide intercept is 33.0 m. The Lens has a shallow plunge in the southwest, steepening down plunge to the northeast and is roughly capped by the central porphyry intrusion. It is interpreted to lie within the main fault in the southwest and is located proximal to the main fault in the northeast.
• The Northern Lens is separated from the Southern Lens by a porphyry dyke swarm but the two lenses were unlikely to have joined. The northern lens is open down dip and plunge, strikes for at least 400 m, is up to 20 m true thickness and has a maximum down dip extent of 120 m thus far defined. This lens is also slightly banded and yields very high-grade gold gossans in the oxide zone above the main high- grade shoot. Peak results from primary sulphide include 20.85 m.
• A Lower Zinc Lens, has been intersected in several drill holes over a strike of 400 m with a vertical height of 30 m and is up to 10 m thick (overall cigar shaped lens). Very high-grade zinc occurs over 3.5 m. This lens is interpreted to be on a separate structure to the east of the Central, Southern and Northern Lenses. The mineralization is typically brecciated with jasperoidal alteration and porphyry dykes intruding along the structure.
The near-surface part of the Terakimti system has been affected by supergene processes with distinctive vertical mineral zonation developed. These are:
• Surficial gold enriched Oxide Zone (gossan). Gold is enriched with little to no sulphide, minor to no copper, zinc or silver and elevated lead. There may be a weak leached zone before the transition.
• Silver Enriched Transition Zone with variable gold. Pyrite remains but no other primary ore minerals are present. There is weak copper as covellite, pyrite, high gold and high silver (300 g/t gold).
• The Supergene Copper Zone which is largely primary with 5 to 20% secondary minerals (mainly covellite, minor chalcocite) with chalcopyrite present. Sphalerite locally remains and only chalcopyrite is significantly affected.
• Primary Zone of which there are several different lenses with different characteristics. The main lenses are massive to sub-massive fine-grained pyrite with overprinting, interstitial and fracture-related chalcopyrite and low-iron sphalerite, with gold and silver (rarely galena) in pyrite or as banded sulphide layers and occasional high- grade stringer zones.