Ceará and Arete are two separate Luna Greenfields gold targets hosted by a south-west trending shear zone located 16 km along strike from the Aurizona Mine (Figure 1). Geochemical and geophysical data combined with geological mapping indicate that these new targets are located in the same structural corridor that hosts the Aurizona gold deposits (Figures 1 and 2). Another smaller artisanal pit, Carana, is located within the target area. These targets will be rated and ranked against other new gold discoveries that Luna is generating in the Luna Greenfields project prior to more advanced exploration.
Figure 1. Location of the Ceará and Arete targets, Luna Greenfields project overlain on 1VD magnetic grid (CPRM, 2008).
Ceará was an active garimpo (artisanal mine) in the 1980s where quartz veins hosted by tonalites were mined. Three flooded pits remain surrounded by tailings dumps. Gold mineralization is associated with outcropping quartz veins and hydrothermal alteration including pyritization. Target geology consists of granites, tonalites and laterites within the Ceará-Arete Sheer Zone (CASZ). The Ceará soil anomaly measures 0.55 km x 0.25 km at a 50 gold parts per billion (PPB Au) cut-off with a maximum value of 1.32 grams of gold per tonne (g/t Au). Rock grab sampling around the pits and further afield returned several high-grade samples including 20.30 g/t Au, 4.17 g/t Au and 2.62 g/t Au. Grab sampling of tailings dumps also returned encouraging grades including 2.93 g/t Au, 2.17 g/t Au and 1.29 g/t Au. Table 1 contains a summary of Luna’s reconnaissance rock and tailings sampling programs at Ceará.
Figure 2. Location of the Ceará and Arete targets within the CASZ – extension of Aurizona mineralized structures into Luna Greenfields. Overlain on total field magnetic grid.
Arete is located 1.5 km ENE from Ceará within the CASZ and was identified through a soil geochemical survey that defined a cohesive linear anomaly measuring 1.00 km x 0.10 km at a 50 ppb Au cut-off with a maximum value of 0.79 g/t Au. Target geology is masked by laterites. Correlation with multielement soil geochemistry shows these laterites may represent weathered basic volcanics. No rock outcrop exists at Arete though several rock grab float samples were collected over the target with best result of 3.31 g/t Au. Table 1 contains a summary of Luna’s reconnaissance rock grab sampling program at Arete. Luna subsequently conducted an auger drill program to test the soil anomaly. Auger holes were drilled on a 100m x 8m grid crossing the anomaly and have defined a 0.5 km long mineralized zone trending east north-east hosted in a basic volcanic unit. The top ten auger drill intervals are shown in Table 2.