The Coringa Project is located in
the southeastern part of the Tapajós gold district where
past production from alluvial sources is estimated between 5 to 30 million
ounces of gold. This district has over 400 alluvial gold occurrences and 20
hard rock gold showings. A regional NW-SE-trending
shear zone, the Tocantinzinho Trend, is associated with many of the gold
occurrences in the district (e.g., Cuiú-Cuiú, Palito, Tocantinzinho, União,
Coringa, and Mato Velho). Mineralization consists of native gold occurring in
quartz-carbonate-sulphide veins or with disseminated sulphides. Pyrite is the
dominant sulphide with minor sphalerite, chalcopyrite and galena.
The Coringa Project is underlain by Proterozoic granites and rhyolitic volcanics which exhibit 2 main structural trends (northwest and north-northwest). The main shear-vein system is coincident with the north-northwest trend (345o) and dips 70o to 90o to the northeast. Five zones of vein mineralization (Valdette, Galena, Mae de Leite, Meio, Come Quieto) are associated with this 7 km long shear zone. In addition, several other, sub-parallel mineralized veins (e.g. Serra, Demetrio) are present.Gold occurs in quartz-sulphide veins which range in thickness from 0.15 to 4 metres. Chlorite-hematite alteration is distal and sericite-pyrite alteration is proximal to the veins.
Serra vein consists of three subparallel veins that are exposed over a strike
length of 1,000 m and to depths of 250 m below surface. The veins trend at an
azimuth of 330 to 340 degrees and dip steeply (75 degrees) to the northeast.
majority of significant gold mineralization at Meio occurs in one main vein that
is interpreted to correlate with Galena and Mae de Leite to the northwest and
Come Quieto to the southeast
. Anfield's drilling concentrated on the central
part of the vein at Meio, testing a strike length of 500 m to depths
approaching 250 m below surface. At Meio, the vein is subvertical or has a steep dip (75 degrees) to the southwest. There
is local evidence that other veins may be present at Meio, but these tend to be
less continuous and contain lower gold grades.