Projects
Sierra Blanca
Encouraging epithermal style gold-silver mineralization was discovered at Veta Chala in the last Quarter 2008. Best intersections included 11.0m @ 3.4 g/t Au and 386 g/t Ag from 46m in hole SBD51, 14.3m @ 2.8 g/t Au and 242 g/t Ag from 31m in hole SBD55, 21.0m @ 0.7 g/t Au and 189 g/t Ag from 33m in hole SBR27 and 3.0m @ 4.3 g/t Au and 236 g/t Ag from 30m in hole SBR38. Sierra Blanca and the nearby Canadon Largo concession form the Santa Cruz Joint venture (Mariana 70%, IAMGOLD 30%).
Location
Sierra Blanca (7,000ha) is 50km N of AngloGold's 6Moz Vanguardia low-sulphidation epithermal gold deposit in the centre of the Deseado Massif, Santa Cruz Province, Southern Argentina.
Ownership
Mariana has earned a 70% interest by spending US$2M by the end of 2008.
Previous Exploration
First pass exploration by IAMGOLD identified epithermal quartz veins over a 7km strike with rock chip assays of up to 1.1 g/t Au and 635 g/t Ag (Lucilla Vein).
Exploration by Mariana
Geological mapping, rock chip sampling and prospecting by Mariana in 2006 discovered 14 new quartz veins/vein breccias/quartz stockworks trending for at least 12km with vein widths up to 4m and 29km of inferred veins.
Scout drilling in early 2007 (22 diamond scout drill holes for 2,995m) tested targets at the Sierra Blanca and Cañadon Largo. Of this, 18 holes (2,523m) tested eight veins strongly anomalous in gold, silver and pathfinder elements, consistent with high-level epithermal silver-gold systems. Ten holes intersected multi-stage quartz veins but six did not reach the planned target, either due to drilling difficulties or structural off-sets.
Highest gold values were only 1.2 g/t Au and 24 g/t Ag (SB 2) over 1m from 28m, and 1.15 g/t Au and 17 g/t Ag over 0.8m from 36.5m (SB4). Despite these disappointing results, Mariana persisted with exploration and discovered new veins at Vetarron and Cero Bola. Ground geophysics (55 line-km of IP/Resistivity and 294 line-km of magnetics) was carried out. The IP indicated a large system of prospective silicified structures, many with coincident chargeability responses.
Veta Chala Discovery
Subsequent prospecting discovered an 1km+ E-W trending vein system at Veta Chala, in the NE Sierra Blanca area with bonanza silver and gold in rock chips and diamond saw channel samples, including 9.4 m @ 2,362 g/t Ag 1.3 g/t Au, 3.4m @ 1,238 g/t Ag, 10 g/t Au and 1m @ 25 g/t Au.
Follow up drilling in late 2008, included sixteen RC drill holes (1,130m) and six diamond drill holes (550m) along the 1,200m Veta Chala trend and other drilling at Lucila and Vetarron, totalling 3,550m.
Encouraging epithermal style gold-silver mineralization was discovered at Veta Chala. Best intersections included 11.0m @ 3.4 g/t Au and 386 g/t Ag from 46m in hole SBD51, 14.3m @ 2.8 g/t Au and 242 g/t Ag from 31m in hole SBD55, 21.0m @ 0.7 g/t Au and 189 g/t Ag from 33m in hole SBR27 and 3.0m @ 4.3 g/t Au and 236 g/t Ag from 30m in hole SBR38.
Review by Dr R Sillitoe
The project was then reviewed by international geological consultant, Dr Richard Sillitoe in early 2009. He concluded that the Chala and Lucila veins intermediate-sulphidation epithermal type, comparable with the bonanza-grade Martha silver deposit (located about 100km SW) and that the Chala Central, Chala West and Chala Splay may contain silver-dominated, bonanza grade ore shoots to a depth of at least 150 m, and merit drill testing. Additionally, he recommended scout drilling for concealed ore shoots at Lucila and La Cresta prospects.
Sillitoe Sierra Blanca Report (pdf)
