Summary:
The Aurizona Property mineralization is characterized as a greenstone-hosted orogenic gold system. Mineralization occurs as structurally-controlled gold deposits including the Piaba deposit, which is currently being mined. Piaba, Boa Esperança, Tatajuba and Genipapo deposits are on and adjacent to the Aurizona Shear Zone (ASZ), a regional northeast-striking structure. Touro is 16 km southwest of the Aurizona Mine which hosts gold mineralization within an intrusive unit. These deposits are hosted by Paleoproterozoic volcano-sedimentary and intrusive rocks of the São Luis Craton, an eastern extension of the Guyana Shield which contains several major Proterozoic gold deposits including Las Cristinas, Omai, and Rosebel, extending from Venezuela to Brazil.
The Property geology is dominated by volcano-sedimentary sequences of the 2.23-2.24 Ga Aurizona Group (Klein et al, 2015), and granitoids of the Tromaí Intrusive Suite. The Aurizona Group is comprised of felsic, intermediate, and mafic volcanic and volcaniclastic rocks, as well as metasedimentary rocks. The bedrock units are covered by Phanerozoic sedimentary basin deposits and recent coastal sediments.
Gold mineralization at Piaba and the other deposits is generally associated with subvertical tabular zones of intense shearing and hydrothermal alteration consisting of quartz-carbonatesericite±chlorite. Quartz±carbonate shear veins are the primary host for gold mineralization with flat to shallow dipping quartz±carbonate extensional veins also carrying gold. Pyrite is the dominant sulphide with lesser arsenopyrite or pyrrhotite, except at Tatajuba and Touro where arsenopyrite mineralization is commonly observed. Native gold is observed within the grey shear veins, commonly occurring along vein margins.
An aerially extensive regolith profile has developed across the Property with distinct effects on geochemical dispersion and physical properties within each regolith domain type. The regolith profile overprints mineralization and can extend to vertical depths of more than 60 m, and is underlain by fresh, sulphide-bearing rocks that host primary gold mineralization.
Piaba
Piaba is a structurally-controlled, tabular, orogenic gold deposit with a strike length of ~3.3 km, width of 10 – 50 m, and down-dip extent of at least 700 m, beyond which the deposit is sparsely explored. The deposit is hosted in the brittle-ductile ASZ that is ENE-WSW striking and steeply north dipping to the NNW.
Within the Piaba deposit, the ASZ system is divided into ten shear zones and/or brittle faults, partially segmenting the deposit with limited offsets. The maximum offset observed is 100 m, whereas most offsets are in the order of 10 m. The Pirocaua fault zone at the east-northeast end of the deposit is a significant structure. This brittle fault zone is up to 350 m wide and locally disrupts the Piaba gold zone with a maximum offset of 75 m. At the western end of Piaba on section 1900W there is a northwest striking fault, which truncates the gold zone at depth. Near surface mineralization continues west of the fault in Piaba west area although the possible offset of the mineralization at depth has not been tested.
Mineralization is primarily hosted in the quartz diorite that is also described as a dike-like c. 2.0 Ga granophyric granodiorite (e.g. Freitas and Klein, 2013; Klein et al., 2015) but has also been interpreted as a cataclasite unit. Ore-related alteration includes strong to intense sericite-carbonate-silica-sulphide alteration in the central part of the structure (i.e. in the quartz diorite) flanked by chlorite-dominant alteration in the footwall and hangingwall. Gold occurs in thin, millimetre to centimetre-scale, and quartz-carbonate ± sulphide± tourmaline bearing shear veins. Native gold is rarely observed at wall rock-vein contacts. Sub-horizontal quartz-carbonate extensional veins commonly cut shear veins and can contain gold. Increased vein density and sulphide abundance are the best indicators of gold mineralization.
Boa Esperança
The Boa Esperança deposit is located approximately one kilometre south of the Piaba deposit and consists of four sub-parallel gold-bearing zones that are continuous along strike for ~1000 m (Figure 7- 5). The four gold-bearing zones are each about 5 ± 2 m wide and developed in a corridor ranging from 40 – 75 m in width, narrowing to 20 m at the northeastern end where there are generally just two zones. The four gold bearing zones coalesce within the saprolite and laterite portions of the eastern margin of the deposit. The deposit extends to at least 230 m below the surface and is hosted within a brittle-ductile structure trending ENE-WSW and dipping steeply (80°–90°) to the NNW.
Mineralization is hosted in strongly altered and deformed Aurizona Group rocks, likely derived from the adjacent Aurizona Group diorite, gabbro, and minor metasedimentary rocks. The mineralized corridor shows moderate to strong silica-sericite-albite-carbonate alteration, along with increased disseminated pyrite (2 – 5 modal percent) and density of quartz-carbonate-sulphide veins.
Tatajuba
The Tatajuba deposit is also hosted within the ASZ, with the eastern end of the deposit located ~2 km west of the western end of the Piaba deposit. The Tatajuba deposit comprises a tabular zone that is east-west striking and steeply north-dipping; the zone measures ~700 m long, 5 – 30 m thick and 300 m in downdip extent. Within the eastern portion of the Tatajuba deposit, the ASZ system is interpreted to be cross-cut by subvertical NNW-trending structures. The maximum offset observed is between sections 200E and 300E, where the deposit is offset by 10 m, through sinistral shearing and/or faulting.
Genipapo
The Genipapo North and South deposits are located about one kilometre east of the eastern margin of the Piaba deposit, with Genipapo North approximately 400 m north of Genipapo South. These deposits form in splays off the ASZ. The geology, geochemistry and magnetic data indicate a horsetail structure off the ASZ structure. Numerous fault structures and discontinuous splays of metavolcanoclastic and ultramafic units have been interpreted at Genipapo and the surrounding area. The metavolcaniclastic sequences are comprised of metatuffs, metagraywackes, phyllites and are in fault contact with ultramafic rocks. Gold mineralization is associated with shear-hosted smoky quartz veins and millimetre-scale extensional veins that form a stockwork. The mineralization forms in quartz ± albite ± sericite alteration with pyrite and arsenopyrite minerals. There is a strong correlation between gold and arsenic.
Touro
Touro is located about 20 km southwest of the Piaba deposit. The Touro deposit is hosted in a coarsegrained DRT and strongly deformed MVC rocks from Aurizona Group. A regional northeast-southwest treading mylonitic shear zone the host rocks which are cut by late andesite and aplite to pegmatite dykes.
The mineralized zone trends 340° and is 600 m long, 130 m thick and roughly 150 m depth extents. Gold mineralization is hosted in albite altered diorite (ADT) with extensional quartz veins system. The ADT unit shows equigranular texture and is composed of albite-silica-sulfide (pyrite ± pyrrhotite ± sphalerite). Extensional veins are the most abundant vein type, composed of quartz ± pyrite ± chlorite ± carbonate that are moderately south dipping to sub-horizontal. Visible gold occurs in both extensional and shear vein types. Gold values are associated with sodium alteration (albite) zones.
Production
Production in 2024 is lower due to the suspension of mining the Piaba pit, the plant being idle for May and June, and the impact of mining lower grade ore from the Tatajuba and Boa Esperança pits.
All production numbers are expressed as metal in doré.
^ Guidance / Forecast.
