Vallecito is located in the north-east of the Province of Jujuy within the Departments of Rinconada and Cochinoca and is 41 km to the east of the restarted Pirquitas Ag-Sn-Zn mine and 55 km to the west of the town of Abrapampa.
Ivan Alberto is a 4 km x 1 km gold-silver-base metal multi-vein mineralized system. Geology and alteration styles indicate a low sulphidation-epithermal-sheeted vein type desposit.
This property is sited on an Ordovician magmatic complex comprising principal dacitic rocks, rhyolite and volcanoclastics which are surrounded by mudstones, greywackes and sandstone units. In the northern part of the property there are two prominent oxide caps.
The first comprises brecciated rocks recemented by dominant hematite and overlying westerly striking sub-vertical stringer veins implying of a possible stockwork system beneath. The second oxide cap is also composed of brecciated rocks recemented with hematite and cut by one or more banded sub-vertical quartz veins, the largest of which is several metres in thickness. Though it is leached at surface, it has the potential for mineralization at depth.
Both of these oxide caps have been tested with surface trenching and general excavation at surface. The maximum depth of this work was only an approximate 7 metres, which did not expose anything other than iron oxides at the base of the excavations. These trials were reportedly carried out some 30 to 40 years ago by the company that operated the now abandoned Pan de Azucar mine 9 km to the north of Vallecito.
Within the southern half of the Vallecito property (Ivan Alberto prospect) there is an underground trial mine reportedly carried out by the same operators. This trial mine extends for an unknown distance on a westerly-striking quartz-barite vein. There is a small water filled shaft at the entrance to the workings. The level beyond is collapsed. A small pile of mineral close to the entrance shows pyrite, quartz and chalcopyrite (copper-pyrites). These trials could easily be re-opened and investigated.
Two different styles of mineralization are seen on the Vallecito property. These comprise two oxide caps sited in the NW quadrant of the property together with a barite vein located in the SW quadrant (Ivan Alberto prospect).
The oxide caps comprise brecciated hematised rocks recemented with hematite and cut by one or more banded quartz veins. These are devoid of other mineralization at surface due to leaching of any possible sulphide mineralization, but are prospective in depth below the zone of oxidation. On the borders of one of these caps fresher rock was traversed by very thin stockwork-type veining trending westwards and associated with sericitization of the host rock.
The quartz-barite vein located separately in the Ivan Alberto prospect also strikes westwards. It is sub-vertical and can be traced for several hundred metres across a valley and hillside where it has been explored by trial mining. A small dump of mineral bearing copper and iron sulphides is located close to a former entrance.
The sulphide mineralization in the veins consists of chalcopyrite, sphalerite, galena, arsenopyrite, pyrite and bismutinite, which are occur as fracture filling, disseminations and banded textures in the shear structures. Gold and silver are associated with iron oxides, in native form as gold, and as argentojarosite containing silver. Iron oxides such as goethite, hematite and jarosite are present in disseminated form as infilling in boxworks and as abundant impregnations in the fractures. The gangue consists of quartz in three generations (milky quartz, hyaline quartz and drusic quartz), barite and calcite.
The alteration assemblage is characterized by weak sericite, clays, kaolinite, silica and pyrite and forms a 1 to 4 meter thick halo in the walls of the veins. A weak supergene argillization is very common in the mineralized area.
Geological mapping has identified a well-defined epithermal vein system hosted in Ordovician rocks striking N40-65E and at least 3.5 km in length where 10 main mineralized structures and accessory sheeted veins occur: Eva, Morocha, Ivana, Mercedes, Colorada, Liliana, Mariana, Irene, Linda and Morena. The veins parallel the bedding and dip 45-85SE; vein thickness ranges between 0.15-5.0m. These veins are substantial quartz vein sets with stock-working of quartz veinlets and sulphide mineralization between them.
The style of mineralization and alteration, in conjunction with the elevated precious and base metals covering such a large area suggests the target contains a Copper-Zinc-Lead-Gold-Silver epithermal system.
This exciting new discovery was made during a follow-up program completed in July 2010 after reconnaissance work, completed in December 2009, identified prospective targets in the area. A total of 856 rock samples have now been collected from the Ivan Alberto prospect and have been assayed for Au and 48 other elements at the ALS Chemex lab in Mendoza, Argentina.
Geochemical sampling has returned values as high as:
Four key zones have been identified for drilling within the 4km long system which have a characteristic metal association (See Map 1). Zone 3 is located in the northeastern part of the system, has a length of 900m and has a strong polymetallic metal association of Au-Cu-Zn-Pb-Ag. Zone 3 provides an excellent drilling target due to its size and the gold values reported (1-7 g/t Au). There are some reported Ag values up to 30.4 g/t in the Eva Vein.
