Barandagh quadrangle is located in northeast of Zandjan, and is a
part of polymetallic region of Tarem-Zandjan. Field evidence and
microscopic studies show an intimate relationship between geochemical
anomalies and alteration zones in this area. Based on the field observations
and mineralogical studis, these zones, in light of extent, locality, and
constituent mineral assemblage, differ from one another, and are scattered
along the main shear zone of the area and the margin of Ghezel-Ozan river.
The major alteration zones in this area are affiliated with the shear zone, and
can be categorized into two discrete alteration types: 1) hypogene acidsulfate
(e.g., silicified, alunitized, advanced argillic, sericitic, and propylitic
zones) and 2) supergene acid-sulfate (characterized by minerals assemblage
such as jarosite, alunite, goethite, gypsum, and native sulfur). Alteration
zone along the margin of Ghezel-Ozan river consists of neutral-pH types of
alterations (consisting mainly of argillic, calc-silicate-bearing, and zeolitic
zones). In general, these alteration zones were developed by the function of a
vast geothermal system during the late Oligocene to Mid-Miocene time.
Date gathered indicate that the discrepancy in reaction rate between the
fluids and the enclosing rocks caused the development of these two types of
alterations. Note the type of alteration zones and the obtained results from
geochemical exploration, show that this area possesses suitable potential for
prospecting of Ag-Au epithermal and polymetallic (Cu, Pb, Zn, Au, Ag)
deposits.