The Guayana Shield
(Map of countries within the Shield)
suttonresources.com
The Guayana Shield ( not to be confused with the neighboring country of Guyana), includes some of the oldest known rocks in the world, and also covers parts of neighboring Guyana, Suriname, French Guiana, Venezuela, and Brazil.
The Guayana Shield is a gold prone area that has recently generated great interest amongst mining companies. In the past, prolific gold production has been derived from simple artisanal methods which spurred a modern techniques approach from several aggressive groups.
The result has been the commissioning of the large Omai mine in Guyana, and the discovery of at least a 12,000,000 ounce reserve (Las Cristinas) in nearby southeastern Venezuela. Las Brisas is said to have a 6,000,000 ounce reserve as well.
The Surinamese portion of the shield consists of three distinct belts of
metamorphic rocks separated by large areas underlain by granitoids and gneisses.
(Map of Suriname... notice that it is in the heart of the Shield)
odci.gov
Primary gold mineralization occurs mostly in quartz and quartz-carbonate veins which are generally restricted to lithological contacts, fold closures and sub-vertical shear corridors. The gold typically occurs as free grains of native gold, often precipitated close to vein margins or interlaced in pyrite crystals in veins or in potassic alteration haloes in adjoining country rocks.
Prolonged chemical weathering has produced a laterite/saprolite profile as deep as 100 metres. A transition zone of variable thickness made up of partly weathered bedrock can often be found below the saprolitic cover. The laterite cover lying over the ore zones is usually enriched in gold.
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