Deposit Type & Model

The Cisneros, occurrences can be classified as a mesothermal lode-gold deposit (Hodgson, 1993).

"Mesothermal gold deposits are mostly quartz-vein-related, gold only deposits with associated carbonatized wall rocks. They occur in low to medium-grade metamorphic terranes of all ages, but only in those that have been intruded by granitoid batholiths. The deposits are characterized by a high gold/silver ratio, great vertical continuity with little vertical zonation, and a broadly syn-tectonic time of emplacement. They are commonly associated with pyrite, arsenopyrite, tourmaline and molybdenite. Mineralization may occur in any rock type and ranges in form from veins, to veinlet systems, to disseminated replacement zones. Most mineralized zones are hosted by and always related to steeply dipping reverse- or oblique-slip brittle-fracture to ductile-shear zones. In mechanically anisotopic host-rock sequences, the shear zones typically are controlled by pre-existing anisotrophies like volcanic flow contacts, dykes and early veins. Shear zone dilation is commonly the result of interference between intersecting sets of shear zones and is part of bulk inhomogeneous flattening in the seismogenic regime of the crust where fluid pressure varied cyclically between sub-lithostatic and supra-lithostatic. At the regional scale, the deposits occur in prograding arc-trench complexes in association with major transcrustal fault zones, linear belts of fluviatile to shallow-marine sedimentary rocks, and small felsic alkali and trondhjemitic intrusions, a co-spatial assemblage of structures and rocks that developed after the main period of accretions-related contractional deformation, but before much of the metamorphism and penetrative fabric. Ore fluids are CO2 rich and have been variously attributed to magmas, metamorphic devolatilization of supracrustal rocks and mantle degassing; most current opinion favours devolatilization of subcreted volcanic and sedimentary rocks, with modification by interaction with the crustal column between the sites of fluid generation and ore deposition"

The initial exploration targets in the Cisneros Project area, particularily in the vicinity of Guayabito are orogenic lode gold deposits also known as mesothermal vein deposits. Numerous examples of this type of deposit are known throughout the world including the Campbell Red Lake deposits in Ontario and the Bralorne deposit in British Columbia. To date, exploration studies have demonstrated that the Guayabito vein systems have all of the attributes of the orogenic vein gold deposit including, but not limited to association with major structural break, quartz-carbonate vein association, low-sulphide assemblage with pyrite, chloritic and sericitically altered wall rock.

Mineralization in the project area is strongly controlled by structure. The mineralization consists of quartz veins with pyrite, chalcopyrite, copper oxides, molybdenum, silver and gold. The alteration is dominated by plagioclase to sericite and mafic minerals to chlorite. Silicification and secondary biotite was also observed, as well as minor potassic alteration locally.