The Coringa Gold Project consists of eight exploration concessions or tenements totaling 23,620.03 hectares (ha). All concessions are owned by Chapleau Exploracao Mineral Ltda., the 100% owned Brazilian subsidiary of Serabi.
Summary:
Deposit Type
In the Coringa gold deposit, shear zones of anomalously high strain are clearly seen. Gold deposition occurs within the quartz veins which were emplaced in the secondary extensional structures associated with the primary shear zones. These deposits were formed during the Archean eon of the Precambrian and are commonly referred to as Archean lode gold deposits.
The Coringa Gold Project is underlain by granitic intrusions of the Maloquinha group and rhyolites of the Iriri group (Salustiano Formation). The granites are granular, medium-grained, and consist of pink feldspar and quartz. The rhyolites are fine to medium-grained, porphyritic, and strongly magnetic. Sanidine and quartz phenocrysts occur in a fine-grained matrix of sanidine-quartz. Minor amounts of biotite also occur in the matrix which has been altered to chlorite.
These giant quartz vein systems, tens of kilometers in length and up to three kilometers in depth, are hosted in brittle-ductile shear zones and are restricted to terrane boundaries. These vein systems are hosted in regional structures that cut through the lithosphere but are usually recognized as strikeslip faults and associated duplexes along with second- and third-order splays. These veins sporadically contain gold mineralization and have extensive carbonate-alteration halos. The occurrence of economic gold mineralization in a deformation zone is often located in places where increased extension has occurred, such as in pull-apart basins.
The majority of these veins are one centimeter to one meter thick and are formed locally. Minerals common to the gold related alteration zone include: carbonates, potassic phyllosilicates (sericite and biotite), alkali feldspar (albite and potash feldspar), chlorite associated calcite and dolomite, iron sulfides (pyrite), quartz, and chloritoid. The most distinctive occurrence of gold is in quartz veins. However, gold can also be associated with alteration sulfides in the wall rock.
There are two dominant structural trends on the Coringa Gold Project property:
• The 310° structures are interpreted as strike-slip faults with probably a dextral (right lateral) sense of displacement.
• Structures trending at 345° are interpreted as R-shears.
Mineralization
Mineralization at the Coringa Gold Projectis associated with a shear/vein system that has a strike length of over 7 km. The mineralized zones vary in thickness from <1 centimeter (cm) up to 14 meters. Several veins (i.e., Galena, Mãe de Leite, Meio, and Come Quieto) occur along the main mineralized corridor and others, such as Serra, Demetrio, and Valdette, form subparallel zones. The average thicknesses for the veins included in the estimate of mineral resources are: Serra 0.52 m, Galena & Mãe de Leite 0.59 m, Meio & Come Quieto 0.41 m, and Valdette 0.80m.
Gold mineralization is almost exclusively associated with quartz-sulphide veining. Pyrite is the main sulphide, but minor concentrations of chalcopyrite, galena, and sphalerite are common. A genetic study of mineralization indicated that pyrite-chalcopyrite (+/- quartz) mineralization occurred first, followed by gold, with galena and sphalerite introduced late. Gold is typically free (or within electrum) and occupies fractures within sulphide grains. It is usually very fine grained and visible gold is rare. Gold in electrum is closely associated with quartz and pyrite. The bulk of the gold has a preference for deposition in the quartz matrix/groundmass (48% locking affinity) and within pyrite (31%) occurring in either fractures or as inclusions, as well as in other sulphides, oxides, and, to a lesser extent and depending on tectonic conditions, in silicates.
Mineralized veins at the Coringa Gold Project are associated with the R-shears. The dip of the veins ranges from 75° to the east to vertical, but they occasionally dip steeply westward (e.g., Galena Vein).
The mineralized veins exposed on the Coringa Gold Project are similar to those found in Orogenic gold deposits.
Alteration
Almost all the core at the Coringa Gold Project is strongly silicified and hematitic. Distal chloritehematite alteration forms wide selvages (50 meters) to veins hosted in rhyolites and narrower selvages (10 meters) to veins hosted in granite. A more proximal pale green sericite-pyrite alteration forms a wider halo in rhyolites (1 meter) compared to granites (0.5 meters).