Geology within the Santa Rosa gold project is dominated by hornblende-biotite diorite and quartz diorite of the Antioquia batholith. The batholith is a calc-alkaline, plutonic intrusive complex belonging to an early- to mid-Cretaceous magmatic arc. Basement geology is a complex elongated mosaic of Palaeozoic and younger autochthonous and allochthonous terranes that were accreted to the South American continent and subjected to transpressional tectonics and episodic subduction-related magmatism.
Mineralization within the Santa Rosa gold project mostly comprises high-grade, gold bearing, mesothermal quartz veins and related saprolite gold deposits. Gold was historically mined from the oxides by sluicing. Artisanal gold miners are presently working high-grade veins. Clusters of colonial era sluice workings and artisanal adits with disseminated mineralization suggest primary gold mineralization at these localities may be potentially bulk minable in sheeted and/or networked vein zones.
Mapping and sampling of the near surface adits, ancient sluiced out areas, surface exposures and ground geochemistry is currently on-going with results to date showing a direct correlation with magnetics, radiometrics and old workings. Since the beginning of 2011, over 280 adits (over 6km total length) and over 60 colonial sluice workings have been surveyed. Many of the adits are exploratory in nature and all are developed in oxidised saprolite. The exploration adits have confirmed disseminated gold mineralisation in the oxides which has been shown to extend over broad zones (up to 35m exposed to date).
The 2011 exploration program is well underway with total direct exploration expenditures estimated at $4.5 million, including 10,000m of diamond drilling commencing in the summer. Drilling under the oxidised zone will determine the extent of economic primary mineralisation contained within the vein stockwork systems. Detailed ground magnetics and a closely-spaced induced polarization geophysical survey are currently underway. Initial drill targets have been established, and diamond drill rig mobilisation is under way.