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Título

OKO WEST: A NEW WORLD-CLASS GOLD DEPOSIT IN THE GUIANA SHIELD

Texto do resumo

The Oko West gold deposit is a grassroots discovery in the Oko region of northwest Guyana. In 2020, Reunion Gold Corporation launched an initial drill program following up on soil geochemistry anomalies (6 km long) and trenching work and discovered gold mineralization in a strongly deformed volcano-sedimentary sequence next to granitoid plutons. The Oko West area was considered a source of historical alluvial gold mining in the region, but there were no artisanal gold workings in the deposit footprint. The deposit continues being drilled, and a mineral resource estimate released in February 2024 contained 4.3 million ounces of gold grading 2.05 g/t in Indicated Resources and 1.6 million ounces of gold in Inferred Resources grading 2.59 g/t. This drill program shows continuous gold mineralization in saprolite and unweathered rocks along a 2 km north-south strike length and at a vertical depth of over 1,000 meters, remaining open along strike and depth. Feasibility and environmental baseline studies are underway, considering open pit and underground mining.

Gold mineralization is hosted by Proterozoic clastic and volcanoclastic rocks of the Barama Group, forming a tabular, 100-200 m wide and steeply east-dipping sequence “sandwiched” between two granitoid bodies: a hanging wall pluton and a footwall sill. Along the contact with the footwall sill, the sedimentary sequence features a shear zone associated with higher gold grades. Recent petrographic and structural studies of the mineralized sequence identified complex fold geometries, crosscutting relationships between structures, and changes in the deformation regime characterized by a coaxial shortening phase (D1a), a transition stage (D1b) and significant gold enrichment and / or endowment during a transcurrent phase (D2). Gold occurrence is documented mostly within pyrite related to preexisting (reworking) S1/0-parallel structures and D2 fault-fill veins, cataclastites and breccias accompanied by carbonate and sericite alteration. Mineralizing fluids circulated and were deposited during polyphase deformation.

Oko West is a classic orogenic gold deposit hosted by a Rhyacian greenstone belt of the Trans-Amazonian Province. It is an excellent example of the mineral endowment of the Guiana Shield, showing that there is still potential to discover large gold systems not previously worked by artisanal miners. Fundamental geological thinking, identifying features from orogenic gold deposits, observing historical artisanal mining sites, and using proper exploration tools will reward diligent explorers.

Palavras Chave

Escudo das Guianas; ouro orogenico; pesquisa mineral