San Simon Regional Geology

The San Simon Project is located in the Precambrian Shield of northeastern Bolivia. It is an extension of the Central Brazil Shield and a geotectonic extension of the Amazonic Craton believed to have consolidated during the Trans-Amazonic Orogeny which ended around 1700 Ma (million years). The shield was affected by two younger orogenies, those of San Ignacio (~1300 Ma) and Sunsas (~1000 Ma).

The major part of the shield area is underlain by a sequence of schists, gneisses and granulites of Lower to Middle Proterozoic age (2,500 to 1,300 Ma) with over 10,000 m thickness.

The San Simon project concessions cover a plateau that rises up to 300 m above the late Tertiary lateritic Amazonian peneplain. The plateau is made up of the Proterozoic Serranía San Simón Group of a low to high grade greenshist facies metamorphic arenaceous sequence. The group is divided into the lower El Cerrito Argillite Formation (300-350 m thick), the middle El Colorado quartzite formation (1,300-1,350 m thick) and the upper Bonanza metagreywacke formation (1,600-1,650 m thick).

The Bonanza Formation is deposited in alternating high and low energy shallow water, shallow depressions and paleotrough features in an oxygenated environment. Local fine lamina with sulphides and carbonates are deposited in stagnant water under anaerobic conditions. Intraformational conglomerates indicate shoaling and temporary withdrawal of the water followed by desiccation and cracking of the surficial muds. Fragments within the sediments suggest an origin from a gneissic basement, volcanic successions and banded iron formation.

The paleocurrents during deposition for the group are principally from the north. Both the El Cerrito and El Colorado Formations had a northwest source of the sediments while the Bonanza Formation had a northeast source. The main metallogenic feature is late kinematic gold mineralization in the schist belt. It includes banded iron formations, shear hosted quartz +/- carbonate gold veins and sediment hosted gold.