Gold exploration in the Kojal-Shamsabad, Hashtjin
The study area is 50 Km2 wide, located in the south of Ardebil Province, southern side of QezelOzan River and 5 Km away from NW of Hashtjin. From metallogeny viewpoint, the area is part of the Tarom- Hashtjin gold bearing zone with Eocene volcanic and pyroclastic rocks and tuff. These rocks have influence by sulfate-rich hydrothermal fluids and show intensive alunitic, argillic, sericitic, and propylitic alterations. Lithology of the area involves andesite, andesite-basalt, trachyandesite, rhyolite and tuff. Among them, tuff and trachyandesite show more intensive alteration. This zone that continues along the southern side of QezelOzan Rive, from east of Kojal village to north of the Shamsabad village, is called Kojal-Shamsabad axis.
Based on geochemical study, the gold grade is low (Max: 9 ppb). Gold anomalies and parageneses have good correlation. Heavy mineral study revealed two gold particles in a sample, and mercury in 35 samples. Analysis of mineralized samples confirms enrichment of gold paragenesis elements including As, Sb, Hg and S in the case which the Hg and As contents are 60 and 386 times higher than Clark, respectively.
Great change of geochemical anomalies, depletion of gold and silver and enrichment of paragenesis elements in the area can be the result of active epithermal gold mineralization. Based on calculation of production coefficient, the current erosion surface is higher than probable mineralized body. Therefore, prospection for gold mineralization should be conducted in deeper depth.