WESTERN GUYANA SHIELD GEOLOGY
The Toroparu Deposit and surrounding satellites are located within the Upper Puruni River watershed of western Guyana and within the Puruni Shear Corridor geologic feature. The Puruni Shear is a northwest trending regional geologic feature that can be traced for several hundred kilometers into the goldfields of eastern Venezuela (see Map below). Multi-million-ounce gold deposits including Toroparu, Aurora, and Omai (mined) hosted in the Guiana Shield volcano-sedimentary belts are related to northwest trending shear corridors.
Satellite imagery combined with geochemical, and geophysical data interpretations indicate gold mineralization is associated with small, intermediate plutons within the Puruni Shear corridor. These indications are confirmed by core drilling at Toroparu and neighboring satellites.
UPPER PURUNI REGION GEOLOGY
The Upper Puruni Region hosts multiple mineralized systems in addition to the 10.5 Measured, Indicated and Inferred (3.15m oz) resources defined within optimized pit shells at Toroparu, SE Zone, and Sona Hill deposits.
Geologic evidence supports exploration for additional deposits and definition drilling of mineralization system discoveries within the sigmoidal flexure structure in the northwest trending Puruni Shear. Coincident anomalous gold geochemical features and geophysical anomalies indicate the potential for additional mineralized system discoveries along intrusive contact zones (e.g. Timmermans, Otomung). Several of these areas have been mined historically for alluvial gold.
TOROPARU & SE ZONE GEOLOGY
The Toroparu Gold Resource lies within a west-north-west oriented elongated deposit of disseminated mineralization along the contact between a sequence of intermediate metavolcanics and a tonalitic to quartz-dioritic composition intrusive.
The system forms a corridor more than 2.7 km long and 200 m to 400 m wide. Mineralization within the system has been encountered at more than 400m in deep and the deposit potential remains open below that depth across several east-west oriented mineralized lenses:
- The Toroparu eastern lens (MAIN in above figure) contains the largest part of the resource and displays the highest gold and copper grades in its core;
- The Toroparu western lens (NW in above figure) contains lower average gold grades, and very low copper grades; and,
- The southeastern lens (SE Pit in above figure) also contains lower average gold and copper grades than the main eastern lens.
Mineralization is hosted within a Chalcopyrite-Bornite-Pyrite-Molybdenite ore assemblage that occurs in a stockwork of disseminated fine fractures and veinlets of dilational aspect. This mineralized corridor exhibits an alteration halo of phyllic to prophylitic character probably representing several hydrothermal alteration phases. These geological and mineralogical features suggest that the Toroparu Gold Deposit is an intrusion related, possibly overprinted porphyry style deposit.
SONA HILL DEPOSIT
The Sona Hill deposit is located 4.9 km southeast of the Toroparu Deposit. It was discovered from regional saprolite geochemical surveys conducted in 2012 and 2013. Subsequent drilling in 2015 and 2016 delineated a shallow lode-gold vein mineralized system dipping westerly toward Toroparu. The Sona Hill deposit is shallow and devoid of copper mineralization.
The Sona Hill shear forms a highly deformed and intensely altered contact zone between the intrusive and an underlying acid volcanic sequence. Gold-Pyrite mineralization occurs mainly within and at the contact between tourmaline-feldspar bearing quartz veins and the intrusive host rock. The veins are surrounded by intense bleaching and alteration halos, both within saprolite and fresh rock types. Mineralization at Sona Hill remains open down dip of the current resource rea and along strike.
Plan View – Block Model Grades
The current resource estimate for the Sona Hill deposit includes 394,000 Measured and Indicated ounces contained in 11.778 tons of saprolite and fresh rock at an average grade of 1.04 g/t: and 351,000 Inferred ounces of Gold contained in 11,538 tons of saprolite and fresh rock at an average grade of 0.95 g/t.
More than 80% of gold mineralization defined at Sona Hill exists at shallow depths ranging from 0 to 120m below surface, with 50,000 oz. of Indicated and 70,000 oz. of Inferred gold resources contained in weathered saprolitic rock to 40m depth. A significant portion of the total saprolite resources is of higher grade, e.g. 38,000 oz. of Indicated gold (76% of total in-pit saprolite resource) at a grade of 1.51 g/t above a 0.8 g/t cut-off-grade.